taxonID	type	description	language	source
B5B28386542C514797EE8D342E7E8EAA.taxon	description	Description. Size and color. Total body length 3.4 - 3.9 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head brown to dark brown, clypeus distinctly paler brown (Fig. 9 B). Pronotum and elytra uniformly dark orange-brown (Fig. 5 A). Venter dark orange centrally, dark red-brown distally (Fig. 5 C). Head. Ground punctation on head coarse. Clypeus with anteromedial emargination, which exposes a broadly rounded to angulate gap between the clypeus and labrum (Fig. 9 B). Mentum strongly depressed in anterior half with a triangular to subtriangular anteromedial notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum moderately coarse (Fig. 5 A). Prosternum tectiform. Mesoventrite with weak elevation forming a thin posteromedial longitudinal carina. Metafemora densely pubescent in basal nine-tenths (Fig. 5 C). Aedeagus. Aedeagus (Fig. 15 H, I) with median lobe subtriangular in shape, widest at base and gradually tapering along entire length; apex acute, distinctly extending beyond the apex of the parameres. Sclerite of the median lobe expanded, but very narrow and weakly developed, apex not reaching the apex of the parameres. Gonopore situated ca. one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins very slightly inwardly curved a long length; width of each paramere gradually narrowed to a blunt (Fig. 15 H) to slightly acute (Fig. 15 I) apex. Basal piece short, ca. one-third the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
B5B28386542C514797EE8D342E7E8EAA.taxon	etymology	Etymology. The species name is derived from the Latin acuminatus, meaning " pointed ", after the condition of the aedeagus, in which the apex of the median lobe is extended and forms an acute point.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
B5B28386542C514797EE8D342E7E8EAA.taxon	distribution	Distribution. Known from a broad range in the eastern Guiana Shield region of South America, from Guyana east to the state of Amapa, Brazil and south to the Amazon River (Fig. 18).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
B5B28386542C514797EE8D342E7E8EAA.taxon	biology_ecology	Biology. This species is relatively widespread and one of the most commonly encountered Chasmogenus in the eastern Guiana Shield. It is found in forested habitats, typically associated with detrital pools, the margins of streams and creeks, and forested swamps (Figs 21 E, 22 C, D). Some specimens have been collected in flight intercept traps (FITs).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
395EBE4287AA5225910E16867602E65A.taxon	description	Description. Size and color. Total body length 4.5 - 5.0 mm. Body form elongate oval with broad, slightly curved lateral margins. Dorsum of head bicolored, frons dark brown, clypeus and labrum distinctly paler (Fig. 9 A). Pronotum and elytra dark orange-brown to dark brown (Fig. 2 A). Venter dark red-brown centrally, dark brown marginally (Fig. 2 C). Abdominal ventrites orange-brown. Head. Ground punctation on head fine. Clypeus with anteromedial emargination, which exposes a rounded to angulate gap between clypeus and labrum (Fig. 9 A). Mentum strongly depressed on anterior half with subtriangular anteromedial notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum fine. Prosternum weakly tectiform. Mesoventrite with weak elevation forming a posteromedial longitudinal carina. Metafemora densely pubescent in basal nine-tenths (Fig. 2 C). Aedeagus. Aedeagus (Fig. 14 A) with median lobe widest at base and very slightly tapering until the apical quarter, then narrowing abruptly to form an acute triangular apex which is even with or slightly extends beyond the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated less than half of one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins straight, with apex slightly inwardly curved and bluntly rounded. Basal piece long, ca. three-quarters the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
395EBE4287AA5225910E16867602E65A.taxon	etymology	Etymology. The species name is derived from the Latin amplius, meaning " larger ", after the large body size of this species, the largest known species of the genus in northern South America.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
395EBE4287AA5225910E16867602E65A.taxon	distribution	Distribution. Known from a few closely situated localities along the Orinoco River in southern Venezuela (Amazonas) (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
395EBE4287AA5225910E16867602E65A.taxon	biology_ecology	Biology. This species has been collected in series along the margins of a small sandy stream that flowed into the Rio Sipapo (Fig. 20 A). Specimens were found by agitating marginal areas where leaf detritus and sand had accumulated.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
790D65B5C65057C9A8DA37CBE1C77EB9.taxon	materials_examined	Additional material examined. Brazil: Roraima: Circa 30 km southeast of Caracarai on BR- 174, 1 ° 35.091 ' N, 61 ° 00.118 ' W, 80 m, 16. i. 2018, leg. Short, Benetti, and Santana, marsh, BR 18 - 0116 - 05 A (37 exs., INPA, SEMC, including DNA Voucher SLE 1774); Murupu River at BR- 174 north of Boa Vista, 3 ° 01.276 ' N, 60 ° 46.565 ' W, 75 m, 13. i. 2018, leg. A. E. Z. Short, muddy backwaters of stream, BR 18 - 0113 - 01 A (3 exs., SEMC); Vicinal 30, 00 ° 43 ' 50.2 " N, 060 ° 25 ' 58 " W, 77 m, 10. i. 2018, leg. Short and Benetti, large roadside ditch with dense vegetation, BR 18 - 0110 - 03 A (24 exs., INPA, SEMC, including DNA voucher SLE 1624); ca. 16 km west of Amajari on BR- 203, 3 ° 36.874 ' N, 61 ° 33.470 ' W, 125 m, 13. i. 2018, leg. Short, Benetti, and Santana, marsh, BR 18 - 0113 - 04 A (9 exs., SEMC); Circa 26 km south of Canta, 2 ° 22.547 ' N, 60 ° 33.538 ' W, 93 m, 11. i. 2018, leg. Short, marsh with lots of emergent vegetation, BR 18 - 0111 - 02 A (1 ex., SEMC); Circa 7 km south of Iracema on BR- 174, 2 ° 6.277 ' N, 61 ° 4.922 ' W, 59 m, 16. i. 2018, leg. Short, Benetti, and Santana, marsh and palm swamp, BR 18 - 0116 - 01 A (1 ex., SEMC); Jundia on BR- 174, 00 ° 12 ' 20.3 " S, 060 ° 41 ' 35.1 " W, 57 m, 10. i. 2018, leg. Short and Benetti, marsh with lots of emergent vegetation, BR 18 - 0110 - 01 A (1 ex .., SEMC); Sitio Bem Querer ca. 3 km west, 1 ° 56.131 ' N, 61 ° 01.737 ' W, 80 m, 16. i. 2018, leg. Short, Benetti, and Santana, BR 18 - 0116 - 04 A (2 exs., SEMC); near Boa Vista, 2 ° 44.558 ' N, 60 ° 47.179 ' W, 105 m, 15. i. 2018, leg. Short, Benetti, and Santana, UV light by drying marsh, BR 18 - 0115 - 03 A, (1 ex., SEMC); BR- 174, c. 50 km NW Boa Vista, 3 18.348 ' N, 60 51.458 ' W, 100 m, 13. i. 2018, leg. Short, marsh, BR 18 - 0113 - 02 A (1 ex., SEMC, DNA Voucher 1629). French Guiana: Yiyi, 5.419, - 53.050 (1 ex., SEMC, DNA Voucher SLE 1856). Guyana: Region 9: near Kusad Mountains, 2 ° 52.204 ' N, 59 ° 55.003 ' W, 124 m, 27. x. 2013, leg. Short, Isaacs, and Salisbury, marshy area, GY 13 - 1027 - 01 A (2 exs., SEMC); Ziida Wao Creek near Kusad Mountains, 2 ° 49.724 ' N, 59 ° 48.546 ' W, 121 m, 25. x. 2013, leg. Short, Isaacs, and Salisbury, stagnant vegetated creek, GY 13 - 1025 - 02 A (3 exs., CBDG, SEMC, including DNA Voucher SLE 1615); Venezuela: Barinas: ca. 13 km southeast of Ciudad Bolivia, 8 ° 19.394 ' N, 70 ° 28.238 ' W, 173 m, 25. i. 2012, leg. Short, Arias, and Gustafson, marsh, VZ 12 - 0125 - 02 A (6 exs., SEMC, including DNA voucher SLE 1080). Cojedes: Rio Caiman Grande at San Brano, 9 ° 39.246 ' N, 68 ° 11.860 ' W, 137 m, 20. i. 2012, leg. Short, Arias, and Gustafson, river margin, VZ 12 - 0120 - 03 A (2 exs., SEMC). Monagas: South of Maturin, 9 ° 16.398 ' N, 62 ° 56.246 ' W, 22 m, 2. ii. 2010, leg. Short, Garcia, and Joly, morichal margin, VZ 10 - 0202 - 02 A (6 exs., SEMC); between Morichal Largo and Tembledor, 9 ° 05.798 ' N, 62 ° 43.618 ' W, 29 m, 2. ii. 2010, leg. Short, Garcia, and Joly, margins of vegetated pond, VZ 10 - 0202 - 03 A (11 exs., MIZA, SEMC; including DNA voucher SLE 1621). Zulia: Sabana de Machango, 10.043017, - 71.007133, 35 m, 29. i. 2012, leg. Short, Arias and Gustafson, margin of artificial pond, VZ 12 - 0129 - 03 A (1 ex., SEMC, DNA Voucher SLE 1082).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
790D65B5C65057C9A8DA37CBE1C77EB9.taxon	description	Description. Size and color. Total body length 3.0 - 3.4 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head bicolored; frons dark brown, clypeus and labrum light tan-brown (Fig. 8 B). Pronotum and elytra light tan-orange, light golden yellow marginally (Fig. 4 D). Venter almost entirely light golden-brown, venter of head and lateral margins of metaventrite light brown (Fig. 4 F). Tibiae orange-brown. Head. Ground punctation on head fine, labrum with slightly finer punctation. Clypeus with anteromedial emargination, which exposes a wide trapezoidal-shaped gap between clypeus and labrum (Fig. 8 B). Mentum weakly to moderately depressed on anterior half with subtriangular anteromedial notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation of pronotum moderate. Prosternum tectiform. Mesoventrite with weak elevation forming a thin posteromedial longitudinal carina. Metafemora densely pubescent with long golden setae in basal six-sevenths (Fig. 4 F). Aedeagus. Aedeagus (Fig. 13 A-D) with outer margins of median lobe strongly situate, such that it appears constricted in the middle; above constriction, margins tapering to form a weakly pointed apex, which slightly extends beyond the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated less than half of one gonopore width below the apex of the median lobe. Parameres with outer margins weakly and evenly curved (Fig. 13 A) to slightly sinuate near the apex (Fig. 14 B-D), with outer apex bluntly rounded and inner apex appear as a right angle. Basal piece long, subequal to slightly shorter than the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
790D65B5C65057C9A8DA37CBE1C77EB9.taxon	distribution	Distribution. This species has a very broad range, occurring from northwestern Venezuela to the coast of French Guiana (Fig. 18). It was originally described from the central region of the Venezuelan Llanos. We have collected it across a very broad range in Venezuela, including the Maracaibo Basin, across the Llanos region, as well as in the Rupununi / Roraima savannah complex in northern Brazil and Guyana. We also report it from the coastal savannahs of French Guiana.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
790D65B5C65057C9A8DA37CBE1C77EB9.taxon	biology_ecology	Biology. Unlike most Chasmogenus, C. australis is almost exclusively associated with lentic or open marsh habitats (Fig. 20 C-F). A few specimens have been taken along the muddy and vegetated margins of large, slow-flowing rivers (morichales).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
636C8FB19559580E826520422D880B66.taxon	materials_examined	Additional material examined (198). Venezuela: Aragua: Henri Pittier National Park, Rio La Trilla, 10.37319 ° N, 67.74250 ° W, 295 m, 4. i. 2009, Short, Miller, Camacho, & Garica [sic], pools, VZ 09 - 0104 - 01 A (25 exs., MIZA, SEMC, including DNA Vouchers SLE 078 and SLE 531); Henri Pittier National Park, Rio Cumboto, 10.39376 N, 67.79597 W, 130 m, 4. i. 2009, leg. Short, Garcia, & Miller, riverside pools, VZ 09 - 0104 - 02 B (7 exs., SEMC); Henri Pittier National Park, 10 ° 21.017 ' N, 67 ° 40.883 ' W, 5. i. 2009, leg. Miller, Camacho, and Garcia, small stream, VZ 09 - 0105 - 01 A (1 ex., SEMC). Guarico: Rio San Antonio, north of Dos Caminos, 9 ° 46.320 ' N, 67 ° 21.177 ' W, 280 m, 8. i. 2009, leg. Short, Miller and Garcia, river margins, VZ 09 - 0108 - 02 A (7 exs., SEMC); same as previous except: leg. Miller & Short, side stream, VZ 09 - 0108 - 02 B (8 exs., SEMC, including DNA Voucher SLE 1613); same as previous except: leg. K. B. Miller, micro habitats, VZ 09 - 0108 - 02 C (2 exs., SEMC); Stream at road crossing, north of Palenque, 9 ° 6.794 ' N, 66 ° 59.595 ' W, 152 m, 8. i. 2009, leg. Short, Garcia, Miller, Camacho and Joly, stream, VZ 09 - 0108 - 03 X (3 exs, SEMC); Rio Guarico, N. San Juan, 9.95788 N, 67.37773 W, 435 m, 8. i. 2009, leg. K. Miller & L. Joly, along river, VZ 09 - 0108 - 01 X (5 exs., SEMC); ~ 15 km south of San Juan, 9 ° 46.321 ' N, 67 ° 21.201 ' W, 255 m, 3. i. 2006, leg. A. E. Z. Short, stream margin and rock pools, AS- 06 - 005 (1 ex., SEMC); ~ 20 km north of Dos Caminos, 9 ° 44.034 ' N, 67 ° 19.003 ' W, 225 m, leg. A. E. Z. Short, gravelly margin of river, AS- 06 - 020 (24 exs., SEMC). Falcon: Rio Ricoa near Dos Bocas, 11 ° 17.424 ' N, 69 ° 26.061 ' W, 170 m, 9. vii. 2009, leg. Short, Sites, Gustafson, Garcia, Camacho, and Inciarte, along river margins, VZ 09 - 0709 - 02 A / L- 1063 (4 exs., SEMC). Lara: Rio Salado west of Arenales, 10 ° 9.260 ' N, 69 ° 57.458 ' W, 490 m, 22. i. 2009, leg. Short, Garcia, and Camacho, gravel stream, VZ 09 - 0122 - 01 X (5 exs., SEMC). Trujillo: Rio Jirajara near Sabana Grande, 9 ° 42.307 ' N, 70 ° 32.570 ' W, 199 m, 29. i. 2012, leg. Short, Arias, and Gustafson, muddy pool in floodplain, VZ 12 - 0129 - 02 A (4 exs., SEMC). Zulia: Perija National Park Tukuko, Rio Manantial, 9 ° 50.490 ' N, 72 ° 49.310 ' W, 270 m, 29. i. 2009, leg. Short, Garcia, and Camacho, gravel margin, VZ 09 - 0129 - 01 A (13 exs., SEMC, including DNA Voucher SLE 534); same data as previous except: 22. ix. 2007, leg. A. E. Z. Short, rock pools / margins, AS- 07 - 020 b (27 exs., SEMC); same data as previous except: 16. vii. 2008, leg A. Short, margins and pools, AS- 08 - 027 (14 exs., SEMC); Perija National Park, Rio Tukuko, 09 ° 50.515 ' N, 72 ° 48.334 ' W, 15. vii. 2008, leg. A. E. Z. Short, upstream of Tukuko, AS- 08 - 029 (1 ex., SEMC); Perija National Park, Toromo, 10 ° 03.058 ' N, 72 ° 42.974 ' W, 435 m, 31. xii. 2005, leg. A. E. Z. Short, small stream and seep, AS- 06 - 001 (5 exs., SEMC); same data as previous except: 28. i. 2009, leg. A. Short, detrital pool, VZ 09 - 0128 - 01 A (3 exs., SEMC); c. 15 km southwest of El Dibujo, 10.79307 N, 72.32331 W, 155 m, 30. xii. 2008, leg. Short, Garcia, and Camacho, muddy puddle, VZ 08 - 1230 - 03 B (1 ex, SEMC); same data as previous except: in stream, VZ 08 - 1230 - 03 X (2 exs., SEMC); Marshy pond, 10.85498 N, 72.30837 W, 81 m, 30. xii. 2008, leg. Short, Garcia, and Camacho, pond margin, VZ 08 - 1230 - 02 X (1 ex., SEMC); 15 km west of Machiques, 10 ° 02.962 ' N, 72 ° 42.615 ' W, 432 m, 31. xii. 2005, leg. A. E. Z. Short, isolated rock pool, AS- 06 - 002 (1 ex., SEMC); Quebrada Riencito, 10.86041 N, 72.32210 W, 95 m, 30. xii. 2008, leg. A. Short and M. Garcia, along margin, VZ 08 - 1230 - 01 B (34 exs., MIZA, SEMC).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
636C8FB19559580E826520422D880B66.taxon	description	Description. Size and color. Total body length 3.5 - 3.7 mm. Body form elongate oval with slightly subparallel lateral margins. Dorsum of head very dark brown to black, anterior margin of labrum slightly paler in color (Fig. 8 C). Pronotum dark brown, distinctly paler at anterior and lateral margins; elytra dark brown, slightly paler at posterior margins (Fig. 3 D). Prosternum and abdominal ventrites dark brown; meso- and metaventrites dark red-brown, trochanters and glabrous portion of femora red-orange (Fig. 3 F). Head. Ground punctation on head fine. Clypeus with anteromedial emargination, which exposes a trapezoidal-shaped gap between clypeus and labrum (Fig. 8 C). Mentum weakly depressed in anterior half with shallowly rounded anteromedial notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation of pronotum fine. Prosternum moderately tectiform. Mesoventrite with median longitudinal carina, which is elevated into an acute tooth medially (Fig. 7 A). Metafemora densely pubescent with long golden setae in basal four-fifths (Fig. 3 F). Aedeagus. Aedeagus (Fig. 11 A-H) with outer margins of median lobe straight and parallel sided, with apex in the form of an acutely pointed triangle, which distinctly extends beyond the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated less than half of one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins slightly curved along entire length, appearing weakly convex; apex bifid, with outer and inner lobes subequal in height but with inner lobe usually narrower. Basal piece long, subequal to the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
636C8FB19559580E826520422D880B66.taxon	distribution	Distribution. Venezuela (Aragua, Falcon, Guarico, Lara, Trujillo, Zulia) (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
636C8FB19559580E826520422D880B66.taxon	biology_ecology	Biology. Nearly all specimens are associated with the margins or side pools of streams and small rivers in the foothills of various Andean regions of Venezuela up to elevations of ca. 500 m. (Fig. 19 A-C, 19 E, F)	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
EAFAA4B49F6958FCB4B6DA60431550FF.taxon	description	Description. Size and color. Total body length 4.5 - 4.9 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head multi-colored, frons dark brown, clypeus dark orange-brown, labrum pale yellow-orange (Fig. 9 C). Pronotum red-orange, elytra pale orange-brown with serial dark brown spots. Head. Ground punctation on head fine. Clypeus with anteroposterior emargination that exposes a wide trapezoidal shaped gap between clypeus and labrum (Fig. 9 C). Mentum moderately depressed in anterior half with subtriangular anteromedial notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum fine. Prosternum mildly tectiform. Mesoventrite with weak elevation forming a posteromedial longitudinal carina. Metafemora densely pubescent in basal nine-tenths. Aedeagus. Aedeagus (Fig. 14 D) with median lobe widest at base, and very slightly tapering until the apical quarter, then narrowing abruptly to form an acute triangular apex which is even with or appears very slightly extended beyond the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated less than half of one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins straight, with apex slightly inwardly curved and bluntly rounded. Basal piece long, ca. four-fifths the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
EAFAA4B49F6958FCB4B6DA60431550FF.taxon	etymology	Etymology. The species is named after the Berbice River in Guyana from where was collected. To be treated as a noun in apposition.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
EAFAA4B49F6958FCB4B6DA60431550FF.taxon	distribution	Distribution. Known only from the type locality along the upper Berbice River in Guyana (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
EAFAA4B49F6958FCB4B6DA60431550FF.taxon	biology_ecology	Biology. This species was collected in detrital leaf packs along the margin of the upper Berbice River (Fig. 22 A).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
267ACFB7D38C539096C83C6CE6189456.taxon	description	Description. Size and color. Total body length 3.7 - 3.8 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head bicolored, frons very dark brown, labrum and clypeus dark orange-brown (Fig. 10 A). Darker patches on mesal portions of clypeus and labrum (Fig. 10 A). Elytra uniformly dark brown. Venter dark orange-brown centrally, dark brown marginally. Head. Ground punctation on head moderately coarse. Clypeus with anteromedial emargination, which exposes a wide smoothly rounded gap between labrum and clypeus (Fig. 10 A). Mentum strongly depressed in anterior half with subtriangular anteromedial notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum moderately coarse. Prosternum even, not tectiform. Mesoventrite with very weak elevation forming a thin posteromedial longitudinal carina. Metafemora densely pubescent in basal nine-tenths. Aedeagus. Aedeagus (Fig. 14 E) with median lobe widest at base and very slightly tapering until the apical fifth, then narrowing to form an acute triangular apex which is even with the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated ca. half of one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins straight, with apex inwardly curved, tapered, and bluntly rounded. Basal piece of medium length, ca. two-thirds the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
267ACFB7D38C539096C83C6CE6189456.taxon	etymology	Etymology. The species is named after Brownsberg Nature Park, the only locality where it is currently known. To be treated as a noun in apposition.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
267ACFB7D38C539096C83C6CE6189456.taxon	distribution	Distribution. This species is only known from Brownsberg Nature Park in Suriname (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
267ACFB7D38C539096C83C6CE6189456.taxon	biology_ecology	Biology. Long series of this species were collected from pools in dirt roads in Brownsberg Nature Park. The pools are large, and often contain detritus as they are through forested areas (Fig. 21 A). One specimen was collected in a forested stream with lots of detritus.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
68AF2A45BDA652309A011844F1D588BD.taxon	description	Description. Size and color. Total body length 4.0 mm. Body form elongate oval with slightly subparallel lateral margins. Dorsum of head bicolored, frons dark brown to mottled orange-brown (Fig. 8 A), anterior margin of labrum and clypeus slightly paler in color. Pronotum mottled dark orange and dark brown, paler on lateral anterior margin (Fig. 3 G). Elytra orange-brown, lateral margins very dark brown (Fig. 3 G). Venter of head dark brown to dark red-brown. Maxillary palps and tarsi exhibit proximodistal gradation from light brown to light tannish yellow. Venter dark red-brown (Fig. 3 I). Head. Ground punctation on head fine. Clypeus with anteromedial emargination which exposes a wide rounded to subtriangular gap between labrum and clypeus (Fig. 8 A). Mentum strongly depressed in anterior half with rounded anteromedial notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum moderately coarse. Prosternum tectiform. Mesoventrite with broad elevation posteromedially, forming a posteromedial longitudinal carina. Metafemora densely pubescent in basal six-sevenths (Fig. 3 I). Aedeagus. Aedeagus (Fig. 12 A) with median lobe very wide at base, wider than the width of one paramere, tapering abruptly in apical quarter to form a narrow triangular projection which is even with to slightly extending beyond the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated ca. half of one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins slightly curved along entire length, appearing weakly convex; apex weakly angled inward. Basal piece long, slightly shorter than the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
68AF2A45BDA652309A011844F1D588BD.taxon	etymology	Etymology. The species name is derived from the Latin castaneus, meaning " of the color of chestnuts ", a reference to the distinctive reddish brown dorsal coloration of this species.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
68AF2A45BDA652309A011844F1D588BD.taxon	distribution	Distribution. Only known from the type locality in northwestern Venezuela (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
68AF2A45BDA652309A011844F1D588BD.taxon	biology_ecology	Biology. All specimens of C. castaneus were collected in marginal pools by a stream (Fig. 19 A, B).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
8953983E25C95B6B9AF32CE9DC81098E.taxon	materials_examined	Material examined. Holotype (male): " Venezuela: Guarico Stat e / 8 ° 8.296 ' N, 66 ° 24.459 ' W / San Nicolasito Field Station / 10. i. 2009; leg. Short & Miller / VZ 09 - 0110 - 02 X; morichal " / " [barcode] / SEMC 0855289 / KUNHM-ENT ", " HOLOTYPE / CHASMOGENUS / clavijoi sp. n. / des. Smith & Short " (MIZA). Paratypes (5): same data as holotype (5 exs. SEMC, including DNA voucher SLE 1198).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
8953983E25C95B6B9AF32CE9DC81098E.taxon	description	Description. Size and color. Total body length 3.8 - 4.5 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head bicolored, frons dark brown, clypeus and labrum orange-brown (Fig. 9 D). Pronotum dark orange brown, slightly paler marginally. Elytra yellow-orange with serial dark brown spots. Head. Ground punctation on head fine. Clypeus with anteroposterior emargination which exposes a broadly rounded gap between clypeus and labrum (Fig. 9 D). Mentum moderately depressed in anterior half with subtriangular anteromedial notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum fine. Prosternum slightly tectiform. Mesoventrite with weak elevation forming a posteromedial longitudinal carina. Metafemora densely pubescent in basal nine-tenths. Aedeagus. Aedeagus (Fig. 14 B) with median lobe widest at base, appearing weakly constricted medially, slightly tapering until the apical quarter, then narrowing abruptly to form an acute triangular apex which is even with the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated less than half of one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins straight, with apex slightly inwardly curved and bluntly rounded. Basal piece long, ca. four-fifths the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
8953983E25C95B6B9AF32CE9DC81098E.taxon	etymology	Etymology. Named in honor of Venezuelan entomologist Jose (Pepe) Clavijo, retired director of MIZA, for all his contributions to Neotropical entomology. To be treated as a noun in apposition.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
8953983E25C95B6B9AF32CE9DC81098E.taxon	distribution	Distribution. Known only from the San Nicolasito Research Station in the Llanos of Venezuela (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
8953983E25C95B6B9AF32CE9DC81098E.taxon	biology_ecology	Biology. This species was collected along the margins of a morichal, a riparian habitat of slow-moving water through a savannah (Fig. 20 B).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
FF4A3DD33E52579A902CFE2273DE07F6.taxon	description	Description. Size and color. Total body length 3.0 - 3.2 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head very dark brown to black, anterior margin of labrum slightly paler in color (Fig. 8 D). Pronotum dark brown, distinctly paler at lateral margins; elytra dark brown. Venter dark red-brown mesally, dark brown marginally. Head. Ground punctation on head fine. Clypeus with anteromedial emargination, which exposes a small angulate gap between clypeus and labrum (Fig. 8 D). Mentum very weakly depressed in anterior half with widely rounded anteromedial notch followed by rounded elevated ridge just posterior of the notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation of pronotum fine. Prosternum tectiform. Mesoventrite with strong elevation forming an acute tooth posteromedially (Fig. 7 B). Metafemora densely pubescent in basal four-fifths. Aedeagus. Aedeagus (Fig. 12 D) with median lobe subtriangular in shape, widest at base and gradually tapering along entire length; apex acute, which extends to the same level as the inner cusp of the parameres. Sclerite of the median lobe not expanded. Gonopore situated slightly less than one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins slightly curved along entire length, appearing weakly convex; apex bifid, with outer lobe slightly more elevated than inner lobe; inner lobe much narrower than outer lobe. Basal piece very long, distinctly longer than the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
FF4A3DD33E52579A902CFE2273DE07F6.taxon	etymology	Etymology. The species name is derived from the Latin cuspis, meaning " pointed ", after the toothed mesoventral carina.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
FF4A3DD33E52579A902CFE2273DE07F6.taxon	distribution	Distribution. This species is known from stream habitats in the Perija and the Coastal Mountains of Venezuela (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
FF4A3DD33E52579A902CFE2273DE07F6.taxon	biology_ecology	Biology. All specimens were collected in the margins of forested stream habitats, typically with gravel margins (Fig. 19 C).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
4C7A2BA01A8E506BB26FCFC11D550A3F.taxon	description	Description. Size and color. Total body length 3.2 - 3.5 mm. Body form elongate oval with slightly subparallel lateral margins. Dorsum of head very dark brown to black with slightly paler preocular patches (Fig. 8 E). Anterior margin of labrum and lateral margins of clypeus sometimes slightly paler. Pronotum dark brown to black centrally, distinctly bright yellow at anterior and lateral margins (Fig. 3 A-B). Elytra dark red-brown to dark brown, slightly paler or bright yellow marginally (Fig. 3 A). Venter dark red brown, abdominal ventrites dark brown. Head. Ground punctation on head fine. Clypeus and labrum contiguous (Fig. 8 E). Mentum weakly depressed in anterior half with shallowly rounded anteromedial notch. Maxillary palps short, just slightly shorter than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum fine. Prosternum moderately tectiform. Mesoventrite with elevation forming a posteromedial longitudinal carina with convex distolateral margins. Metafemora densely pubescent in basal four-fifths (Fig. 3 C). Aedeagus. Aedeagus (Fig. 12 B, C) with outer margins of median lobe straight and parallel sided, with apex in the form of an acutely pointed triangle, which slightly extends beyond the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated less than half of one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins slightly curved along basal four fifths, appearing weakly convex, then curved slightly outward at apex; apex very weakly bifid, with outer lobe more elevated than inner lobe; inner lobe minute, almost appearing absent. Basal piece long, ca. four-fifths the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
4C7A2BA01A8E506BB26FCFC11D550A3F.taxon	etymology	Etymology. The species name is derived from the Latin flavus, meaning " yellow ", after the distinct yellow margins of the pronotum and elytra.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
4C7A2BA01A8E506BB26FCFC11D550A3F.taxon	distribution	Distribution. Known from the Andean States of Tachira and Barinas (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
4C7A2BA01A8E506BB26FCFC11D550A3F.taxon	biology_ecology	Biology. A long series of this species was collected in a small pool that was formed by a road-cut in the Andes (Fig. 19 D). It was being fed by a small stream / seepage, in which two additional specimens were collected. The specimen from Tachira was found in a small pool along a dirt road.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
2D8F56814CD05BBF8AC475B5201C5F9D.taxon	description	Description. Size and color. Total body length 3.3 - 3.8 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head bicolored, frons and clypeus pale to dark brown, labrum pale yellow-brown (Fig. 9 F). Pronotum and elytra dark orange-brown to dark brown. Head. Ground punctation on head fine, slightly finer on labrum. Clypeus with anteromedial emargination, which exposes a rounded to angulate gap between the labrum and clypeus (Fig. 9 F). Mentum moderately depressed in anterior half with subtriangular notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum fine. Prosternum very weakly tectiform. Mesoventrite with weak elevation forming a posteromedial longitudinal carina. Metafemora densely pubescent in basal nine-tenths. Aedeagus. Aedeagus (Fig. 14 C) with median lobe widest at base and very slightly tapering until apical fifth, then narrowing to form an acute triangular apex which is even with the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated less than half of one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins straight, with apex slightly inwardly curved and bluntly rounded. Basal piece long, ca. four-fifths the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
2D8F56814CD05BBF8AC475B5201C5F9D.taxon	etymology	Etymology. The species is named after the community of Cano Gato, from where the species was collected. To be treated as a noun in apposition.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
2D8F56814CD05BBF8AC475B5201C5F9D.taxon	distribution	Distribution. Known from several closely situated localities in southern Venezuela (Amazonas) (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
2D8F56814CD05BBF8AC475B5201C5F9D.taxon	biology_ecology	Biology. This species has been collected in stream margins and associated stream habitats such as nearby detrital pools (Fig. 20 A).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
73A338D45D3D57ECAE9AC2104AA961DC.taxon	description	Description. Size and color. Total body length 3.6 - 4.0 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head bicolored, frons dark orange-brown, clypeus and labrum dark orange to dark yellow-orange (Fig. 10 C). Pronotum and elytra dark orange-brown. Venter dark red-brown mesally, dark brown marginally. Head. Ground punctation on head moderately coarse. Clypeus with anteroposterior emargination, which exposes a rounded to angulate gap between clypeus and labrum (Fig. 10 C). Mentum moderately depressed in anterior half with rounded notch on anteromedial margin. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum moderately coarse. Prosternum even, not tectiform. Mesoventrite with very weak elevation forming a thin posteromedial longitudinal carina. Metafemora densely pubescent in basal nine-tenths. Aedeagus. Aedeagus (Fig. 14 G, H) with median lobe widest at base and very slightly tapering along entire length, terminating in a bluntly triangular apex which is distinctly shorter than the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated nearly one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins straight, with apex slightly inwardly curved and bluntly rounded. Basal piece long, ca. three-quarters the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
73A338D45D3D57ECAE9AC2104AA961DC.taxon	etymology	Etymology. This species is named after the Guiana Shield, the region of South America from which it is known. To be treated as a noun in apposition.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
73A338D45D3D57ECAE9AC2104AA961DC.taxon	distribution	Distribution. This species has been found at several localities in Guyana and Suriname (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
73A338D45D3D57ECAE9AC2104AA961DC.taxon	biology_ecology	Biology. This species was found in a variety of habitats including a forested swamp, ephemeral detrital pools, general creek margins and a large sandy creek (Fig. 21 F). It was also collected passively via a flight intercept trap. A single specimen was collected from water in a dead palm leaf on the ground.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
D0397F55EFA4546EA48FA055D5A9314C.taxon	description	Description. Size and color. Total body length 3.5 mm. Dorsum of head, pronotum and elytra uniformly dark brown. Venter slightly lighter brown. Head. Ground punctation on head fine. Clypeus with anteroposterior emargination which exposes a very narrow, broad gap between clypeus and labrum. Mentum strongly depressed in anterior two-thirds with triangular anteromedial notch. Maxillary palps long, as long as width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum moderately coarse. Surface of prosternum even, not tectiform. Mesoventrite with weak elevation forming a posteromedial longitudinal carina. Metafemora densely and uniformly pubescent in basal nine-tenths. Aedeagus. Aedeagus (Fig. 16 E-H) with median lobe highly modified, appearing as a narrow subparallel-sided strap and partly rotated laterally, with apex extending to the apex of the parameres to slightly beyond. Sclerite of the median lobe extremely well developed and appearing as a thin curved strut that extends the full length of the genitalia. Gonopore oriented laterally (Fig. 16 F); situated more than twice gonopore width below the apex of the median lobe. Parameres asymmetrical, with left paramere wider than right paramere; outer margins of parameres strongly sclerotized, with the sclerotized region on the right paramere thicker than the left. Aedeagus, especially the parameres, thickened, such that it takes on a three-dimensional appearance (Fig. 16 F, G); in lateral view widest at base with dorsal surface flat with ventral surface graduating tapering to the apex. Basal piece short, less than half the length of the parameres; partly obscured by the strongly sclerotized and enlarged base of the median lobe and parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
D0397F55EFA4546EA48FA055D5A9314C.taxon	etymology	Etymology. The species name is derived from the Latin ignotus, meaning " strange ", after the bizarre form of the aedeagus.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
D0397F55EFA4546EA48FA055D5A9314C.taxon	distribution	Distribution. Only known from the Adolpho Ducke Forest Reserve in Manaus, Brazil.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
D0397F55EFA4546EA48FA055D5A9314C.taxon	biology_ecology	Biology. One specimen was collected in an isolated forest detrital pool near Igarape Barro Branco, while another series of specimens came from a flight intercept trap in the forest.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
220F1134F685576EB449C842D3699397.taxon	description	Description. Size and color. Total body length 3.2 - 3.5 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head multi-colored, frons dark brown, clypeus slightly paler, labrum distinctly paler (Fig. 10 C). Pronotum dark orange-brown, slightly paler marginally. Elytra uniformly dark orange-brown to dark brown. Venter orange-brown mesally, dark brown marginally. Head. Ground punctation on head fine to moderately dense. Clypeus with anteromedial emargination which exposes a shallowly rounded gap between the labrum and the clypeus (Fig. 10 C). Mentum strongly depressed in anterior two-thirds with triangular notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum fine. Prosternum very weakly tectiform. Mesoventrite with weak elevation forming a posteromedial longitudinal carina. Metafemora densely and uniformly pubescent in basal nine-tenths. Aedeagus. Aedeagus (Fig. 15 E) with median lobe nearly parallel-sided but curved slightly to the left; apex bluntly rounded, distinctly extending beyond the apex of the parameres. Sclerite of the median lobe expanded and developed into a long, narrow crescent. Gonopore situated near the base of the median lobe. Parameres symmetrical, with outer margins strongly sinuate; the basal half of the parameres parallel sided with apical half appearing greatly expanded, then tapering to a blunt apex. Basal piece short, ca. one-third the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
220F1134F685576EB449C842D3699397.taxon	etymology	Etymology. The species name is derived from the Latin ligula, meaning " tongue " after the broad and extended tongue-like form of the median lobe of the aedeagus.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
220F1134F685576EB449C842D3699397.taxon	distribution	Distribution. Known from lowland rainforest near the base of Mt. Kasikasima in southern Suriname (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
220F1134F685576EB449C842D3699397.taxon	biology_ecology	Biology. Two of the three collecting events for this species were from small sandy streams in dense rainforest (Fig. 21 B). A single specimen was also collected from a very large nearby detrital pool that was draining into a stream.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
5C1D8F362A8759838441AD89F2C949E5.taxon	description	Description. Size and color. Total body length 2.9 - 3.3 mm. Body form very elongate oval with straight, subparallel lateral margins. Dorsum of head very dark brown to black (Fig. 8 F). Pronotum and elytra uniformly dark brown. Prosternum dark orange to dark brown. Mesoventrite uniformly dark orange to dark brown. Metaventrite dark brown, slightly paler on posterior margin. Trochanters and glabrous portion of femora red-orange. Abdominal ventrites dark brown, slightly paler mesally (Fig. 4 C). Head. Ground punctation on head fine. Clypeus and labrum contiguous (Fig. 8 F). Mentum very weakly depressed in anterior half with triangular notch, followed by a medial elevated curved ridge situated posterior to triangular notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum fine. Prosternum moderately tectiform. Mesoventrite with weak elevation forming a posteromedial longitudinal carina with its distolateral margins slightly convex. Metafemora densely pubescent in basal three-fourths (Fig. 4 F). Aedeagus. Aedeagus (Fig. 12 E-I) with median lobe subtriangular in shape, widest at base and gradually tapering along entire length; apex acute, which extends slightly beyond the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated slightly more than two gonopore widths below the apex of the median lobe. Parameres symmetrical, with outer margins slightly curved, appearing weakly convex in basal three-quarters, then abruptly angled outwards; apex bifid, appearing " mitten shaped ", with outer lobe very large, rounded, and directed outwards, and inner lobe very small and slightly more acuminate. Basal piece long, ca. as long as the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
5C1D8F362A8759838441AD89F2C949E5.taxon	etymology	Etymology. The species name is derived from the Latin lineatus, meaning " linear ", after the straight parallel-sided body form and also for the linear, unemarginated anterior margin of the clypeus.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
5C1D8F362A8759838441AD89F2C949E5.taxon	distribution	Distribution. This species is known from lowland gravel streams in the Andean region of Venezuela (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
5C1D8F362A8759838441AD89F2C949E5.taxon	biology_ecology	Biology. This species can be found in abundance in gravel streams along the foothills of the Merida Andes, especially exposed areas of gravel and sand with algae (Fig. 19 E, F).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
77030676C7F65C96B0B7C8A8C8AB0B1E.taxon	description	Description. Size and color. Total body length 3.5 - 3.7 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head bicolored, frons dark red-brown, clypeus and labrum slightly paler (Fig. 10 D). Pronotum and elytra uniformly dark brown. Venter uniformly dark brown (Fig. 5 F). Head. Ground punctation on head moderately coarse. Clypeus with medial anteroposterior emargination which exposes a very narrow, wide gap between the clypeus and labrum (Fig. 10 D). Mentum strongly depressed in anteromedial two-thirds with subtriangular notch. Maxillary palps long, longer than width of head immediately anterior to the eyes. Thorax. Ground punctation on pronotum fine. Prosternum tectiform. Mesoventrite with elevation forming a posteromedial longitudinal carina, increasing in elevation anteroposteriorly with highest elevation near protrochanters; slightly convex along outer margins. Metafemora densely pubescent in basal six-sevenths (Fig. 5 F). Aedeagus. Aedeagus (Fig. 15 A-D) with median lobe nearly parallel-sided and widest in basal half, then angled slightly to the left and tapering gradually to a weakly acuminate apex, distinctly extending beyond the apex of the parameres. Sclerite of the median lobe expanded and developed into a long, narrow sliver with a sharply acute apex that extends to the apex of the parameres. Gonopore situated in the middle of the median lobe, ca. two gonopore widths below the apex. Parameres symmetrical, with outer margins strongly bisinuated, giving the margins a weakly undulating appearance, apical half not wider than basal half; apex bluntly rounded. Basal piece short, ca. one-third the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
77030676C7F65C96B0B7C8A8C8AB0B1E.taxon	etymology	Etymology. The species name is derived from the Latin pandus, meaning " bent " after the curved sclerite of the medial lobe of the aedeagus.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
77030676C7F65C96B0B7C8A8C8AB0B1E.taxon	distribution	Distribution. Known from Brazil (Amapa), Suriname (Para District), and French Guiana (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
77030676C7F65C96B0B7C8A8C8AB0B1E.taxon	biology_ecology	Biology. Specimens from French Guiana and Suriname were collected via a Flight Intercept Trap. The single specimen from Brazil was collected by floating detritus in a forested seepage.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
73228F3ED88551968CD578044BB1472C.taxon	description	Description. Size and color. Total body length 4.3 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head dark brown, labrum distinctly paler. Pronotum and elytra uniformly dark brown. Venter dark orange-brown. Head. Ground punctation on head fine. Clypeus with anteromedial emargination which exposes trapezoidal gap between clypeus and labrum. Mentum moderately depressed in anterior half with triangular anteromedial notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum fine. Prosternum mildly tectiform. Mesoventrite with weak elevation forming a posteromedial longitudinal carina. Metafemora densely and uniformly pubescent in basal nine-tenths. Aedeagus. Aedeagus (Fig. 14 F) with median lobe widest at base, appearing weakly constricted medially, then narrowing abruptly in the apical fifth to form an acute triangular apex which is slightly below the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated less than a third of one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins straight, with apex slightly inwardly curved and bluntly rounded. Basal piece long, ca. four-fifths the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
73228F3ED88551968CD578044BB1472C.taxon	etymology	Etymology. Named in honor of Sarah C. Schmits, a longtime member of the Short Lab who has provided invaluable support to advance and disseminate knowledge of aquatic beetles.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
73228F3ED88551968CD578044BB1472C.taxon	distribution	Distribution. Known only from the type locality in Suriname (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
73228F3ED88551968CD578044BB1472C.taxon	biology_ecology	Biology. This species was collected from a forested swamp habitat (Fig. 21 D).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
E394B9E153C35218B5D72E0B1C326C64.taxon	description	Description. Size and color. Total body length 4.9 - 5.0 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head dark brown. Pronotum dark brown with slightly paler lateral margins, elytra uniformly dark brown. Head. Ground punctation on head fine. Clypeus with anteromedial emargination, which exposes broadly rounded shaped gap between clypeus and labrum. Mentum moderately depressed in anterior half with rounded anteromedial notch followed by rounded elevated ridge just posterior of the notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum fine. Prosternum mildly tectiform. Mesoventrite with very weak elevation forming a posteromedial longitudinal carina. Metafemora densely and uniformly pubescent in basal nine-tenths. Aedeagus. Aedeagus (Fig. 15 F) with median lobe widest at base, nearly parallel sided in basal three-quarters, then narrowing abruptly to form an acute triangular apex which is even with or slightly extends beyond the apex of the parameres. Sclerite of the median lobe not expanded. Gonopore situated less than half of one gonopore width below the apex of the median lobe. Parameres symmetrical, with outer margins straight, with apex very slightly inwardly curved and bluntly rounded. Basal piece long, ca. as long as the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
E394B9E153C35218B5D72E0B1C326C64.taxon	etymology	Etymology. Named after the Sinnamary River, close to where it was collected. To be treated as a noun in apposition.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
E394B9E153C35218B5D72E0B1C326C64.taxon	distribution	Distribution. Only known from the type locality in French Guiana (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
E394B9E153C35218B5D72E0B1C326C64.taxon	biology_ecology	Biology. This species was collected from a clear water creek.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
2045C95AD4F151098C938217F213E5CA.taxon	materials_examined	Material examined (4). Guyana: Region 6: Upper Berbice, Basecamp 2, 4 ° 45.301 ' N, 58 ° 00.404 ' W, 49 m, 26. ix. 2014, leg. Short, Salisbury and La Cruz, shallow detrital pools in forest draining into creek, GY 14 - 0926 - 01 A (4 females, CBDG, SEMC including DNA Voucher SLE 1783).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
A3EBDEBF036E5B4883DE5310733DB7B7.taxon	description	Description. Size and color. Total body length 3.3 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head bicolored, frons dark red-brown, clypeus and labrum dark orange-brown. Pronotum and elytra uniformly dark brown. Head. Ground punctation on head moderately coarse. Clypeus with anteromedial emargination, which exposes angulate gap between clypeus and labrum. Mentum moderately depressed in anterior half with anteromedial subtriangular notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum moderately coarse. Prosternum mildly tectiform. Mesoventrite with very weak elevation forming a posteromedial longitudinal carina. Metafemora densely pubescent in basal six-sevenths. Aedeagus. Aedeagus (Fig. 16 A-D) with median lobe highly modified, appearing as a narrow subparallel-sided strap and partly rotated laterally, with apex extending to the apex of the parameres. Sclerite of the median lobe extremely well developed and appearing as a thin curved strut that extends the full length of the genitalia. Gonopore oriented laterally (Fig. 15 B); situated twice gonopore width below the apex of the median lobe. Parameres asymmetrical, with left paramere wider than right paramere; outer margins of parameres strongly sclerotized, with the sclerotized region on the right paramere thicker than the left. Aedeagus, especially the parameres, thickened, such that it takes on a highly three-dimensional appearance (Fig. 16 B, C); in lateral view widest in basal half, with dorsal surface strongly convex, with ventral surface nearly flat. Basal piece short, less than half the length of the parameres; partly obscured by the strongly sclerotized and enlarged base of the median lobe and parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
A3EBDEBF036E5B4883DE5310733DB7B7.taxon	etymology	Etymology. Named after Tafelberg, a low elevation sandstone tepui in central Suriname. To be treated as a noun in apposition.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
A3EBDEBF036E5B4883DE5310733DB7B7.taxon	distribution	Distribution. This species only known from the summit of Tafelberg Tepui in Suriname (Fig. 17).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
A3EBDEBF036E5B4883DE5310733DB7B7.taxon	biology_ecology	Biology. The single specimen of this species was collected from forested pools which contained extremely dense layers of leaf litter detritus (Fig. 21 C).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
9624C9B41A2D5F2998298842D6691D90.taxon	description	Description. Size and color. Total body length 3.8 - 4.0 mm. Body form elongate oval with slightly curved lateral margins. Dorsum of head dark brown, clypeus slightly paler (Fig. 9 E). Pronotum dark orange-brown, distinctly paler marginally. Elytra uniformly dark brown. Venter dark red brown to dark brown. Head. Ground punctation on head fine to moderately coarse. Clypeus with anteromedial emargination, which exposes a trapezoidal gap between the clypeus and labrum (Fig. 9 E). Mentum strongly depressed in anterior half with subtriangular anteromedial notch. Maxillary palps long, longer than width of head immediately posterior to eyes. Thorax. Ground punctation on pronotum moderately coarse. Prosternum tectiform. Mesoventrite with elevation forming a posteromedial longitudinal carina with the lateral margins convex. Metafemora densely pubescent in basal six-sevenths. Aedeagus. Aedeagus (Fig. 15 G) with median lobe nearly parallel-sided and widest in basal half, then angled slightly to the left and tapering gradually to a weakly acuminate apex, distinctly extending beyond the apex of the parameres. Sclerite of the median lobe expanded and developed into a wide angulate sliver with a sharply acute apex that extends to the apex of the parameres. Gonopore situated ca. 1.5 gonopore widths below the apex of the median lobe. Parameres symmetrical, with outer margins strongly bisinuated, giving the margins a weakly undulating appearance, apical distinctly narrower than basal half; apex bluntly rounded. Basal piece short, ca. one-third the length of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
9624C9B41A2D5F2998298842D6691D90.taxon	etymology	Etymology. The species name is derived from the Latin undulatus, meaning " wavy ", after the curvy and sinuated margins of the parameres.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
9624C9B41A2D5F2998298842D6691D90.taxon	distribution	Distribution. This species is known from several collections near Mount Ayanganna in western Guyana.	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
9624C9B41A2D5F2998298842D6691D90.taxon	biology_ecology	Biology. Series of this species were collected in forested detrital pools (Fig. 22 B).	en	Smith, Rachel R., Short, Andrew Edward Z. (2020): Review of the genus Chasmogenus Sharp, 1882 of northeastern South America with an emphasis on Venezuela, Suriname, and Guyana (Coleoptera, Hydrophilidae, Acidocerinae). ZooKeys 934: 25-79, DOI: http://dx.doi.org/10.3897/zookeys.934.49359, URL: http://dx.doi.org/10.3897/zookeys.934.49359
