Atelopus colomai Plewnia, Terán-Valdez, Culebras, Boistel, Paluh, Quezada Riera, Heine, Reyes-Puig,

Atelopus colomai Plewnia, Terán-Valdez, Culebras, Boistel, Paluh, Quezada Riera, Heine, Reyes-Puig,

Salazar-Valenzuela, Guayasamin and Lötters, 2024

Figs. 12–13 View FIGURE 12 View FIGURE 13

Atelopus colomai Plewnia, Terán-Valdez, Culebras, Boistel, Paluh, Quezada Riera, Heine, Reyes-Puig, Salazar-Valenzuela,

Guayasamin and Lötters, 2024b: 239 from “ ECUADOR: Pastaza: Río Pucayacu , N of Diez de Agosto “, CJ 12198 , leg .

Jaime Culebras, Amanda B. Quezada Riera, Danilo Medina and Amadeus Plewnia. Atelopus spumarius non-Cope.— Rueda-Almonacid et al. 2005: 126; Ron et al. 2009: 58; Carrillo-Bilbao & Martin-Solano

2013: 48; Tarvin et al. 2014: 291. Atelopus spumarius spumarius non-Cope.— Duellman & Lynch 1969: 232; Lötters 1996: 47. Atelopus pulcher non-Boulenger.— Rivero 1963: 113; Gascon 1989: 235; Patzelt 1989: 270 (color illustration of paratype ZFMK

44976); Lötters et al. 2002b: 104. Atelopus pulcher pulcher non-Boulenger.— Peters 1973: 42. Atelopus aff. spumarius .— Culebras et al. 2023: 180. Atelopus sp. (aff. A. pulcher ).— Lötters et al. 2002a: 184. Atelopus sp. 1 ( spumarius complex).— Womack et al. 2018: 2. A. sp. ( spumarius complex from Puyo, Ecuador).— Marcillo-Lara et al. 2020: 11. A. sp. Otoyacu ( spumarius complex).— Jaynes et al. 2022: 6. A. sp. cf. spumarius Centro Oriente.— Lötters et al. 2023: Supplementary Table 1.

Holotype. ECUADOR: Pastaza: Río Pucayacu , N of Diez de Agosto (1°22’43”S, 77°51’53”W, 951 m asl), CJ 12198 ( Figs. 12–13 View FIGURE 12 View FIGURE 13 ), adult male, leg. 23 September 2021 by Jaime Culebras, Amanda B. Quezada Riera, Danilo Medina and Amadeus Plewnia. GoogleMaps

Paratopotypes. CJ 12200 , 12405–12406 , 12408–12409 , 12425 adult females, same data as holotype GoogleMaps .

Paratypes. ECUADOR: Pastaza: NW of El Triunfo (1°23’43”S, 77°47’50”W, 1,020 m asl), CJ 12196–12197 , 12199 , adult males, leg. 22 September 2021 by Jaime Culebras, Amanda B. Quezada Riera, Danilo Medina, Zane Libke and Amadeus Plewnia GoogleMaps ; Pastaza: Reserva Otoyacu (1°22’27”S, 77°51’07”W, 920 m asl), CJ 12341 , 12431 , adult males, and CJ 8188 , 12430 , adult females, leg. unknown GoogleMaps ; Pastaza: Finca la Argentina N from Puyo (1°27’38.31”S, 77°58’58”W, 960 m asl), DHMECN-INABIO 18995, adult female, leg. 17 August 2023 by Juan P. Reyes Puig, José Ignacio Segovia Larrea, Paulet Benavidez, Nanta Kuja, Patricio Vinueza GoogleMaps ; Pastaza: Río Cononaco , ZFMK 44976 About ZFMK , subadult female, leg. April 1986 by Erwin Patzelt ; Pastaza: Río Villano, near Villano , BMNH 1970.117 , 1970.118 (375 m asl), adult females, leg. date unknown, by Ramón Olalla .

Referred material. ECUADOR: Orellana: Yasuní National Park , road from Pompeya Sur to Iro on km 38, QCAZ 32664 View Materials ; Yasuní National Park , road from Pompeya Sur to Iro on km 66, QCAZ 5006 View Materials , 5234 View Materials , 7015 View Materials , 11126 View Materials , 77404 View Materials ; Pastaza: Reserva Otoyacu, CJ 8187 , 9883 , 12429 , 12826–28 , 12835 ; Río Pucayacu , CJ 12407 , 12697 ; 2.5 km SE of Puyo , USNM 193476 About USNM , 194838 About USNM , JAP 1937–1938; Río Puyo , 3 km S Puyo, KU 121385 ; trail from Unión Base to Rosario Yacu, SE of Puyo, MCZ Herp A 95683–A95688, A-95692–6; Veracruz, ca. 10 km E of Puyo , USNM 193477 About USNM , KU 120480–120485 ; Río Oglán, GOV S939; km 6 on road from San Ramón to El Triunfo, Río Pucayacu , QCAZ 30617 View Materials , 30896 View Materials , 31325–31326 View Materials , 33304 View Materials , 36956 View Materials , 37270–37271 View Materials , 37275 View Materials , 37372 View Materials , 37405–37406 View Materials , 37663– 37664 View Materials , 3766–37668 View Materials , 37710–37717 View Materials , 37721–37722 View Materials , 39545 View Materials , 40489 View Materials , 40512 View Materials , 46483–46486 View Materials , 46491–46493 View Materials , 46850 View Materials , 50579 View Materials ; Finca de la Cooperativa Mariscal Sucre, Río Pucayacu , QCAZ 50291 View Materials ; Parroquia Teniente Hugo Ortiz, QCAZ 17780 View Materials ; Cononaco , UTA WWL 3669 ; Canelos , MCZ Herp A 17927–A17928; Baños and Canelos, AMNH 16713–16715 About AMNH ; Río Villano : BMNH 1970.68 – 1970.69 ; Puyo , FMNH 28078 About FMNH ; historic province Santiago–Zamora (now provinces Zamora Chinchipe and Morona Santiago), NHRM RRB /1937.809.3262 (2 specimens) .

Definition. Atelopus colomai is placed in the genus Atelopus based on its mt and nc markers nested within Atelopus (and with the 16S rRNA fragment showing uncorrected p–distance <3% to the genus type species A. flavescens Duméril and Bibron ), on having presacrals I and II fused, and on the presence of a gastromyzophorous tadpole with a ventral belly sucker. The species is dinstinguished from all other species by the combination of the following characters: (1) A small-sized species with mean SVL of adult males 23.2 ± 1.46, N = 6, and females 29.8 ± 2.05, N = 10; (2) slender body ( SW / SVL = 0.261 ± 0.020 in 6 males, 0.260 ± 0.016 in 10 females) with (3) long legs ( TIBL / SVL = 0.433 ± 0.028 in 6 males, 0.443 ± 0.021 in 10 females) and (4) acuminate snout, protruding beyond apex of lower jaw; (5) tympanic membrane absent, tympanic annulus not visible, columella present, ostia pharyngea present; (6) phalangeal formula of hand 1-2-3-3; webbing absent on hand; (7) first finger short ( THBL / HAND = 0.448 ± 0.024 in 6 males, 0.425 ± 0.066 in 10 females), in males with keratinized dark brown spiculae forming the nuptial pad; (8) phalangeal formula of foot 2-2-3-4-3, webbing formula of toes I 0–0 to 1 II 0to 1 / 2 –1 III 1 / 2 to 1–2¼ to 3 IV 2½ to 3– 1 / 2 V; (9) skin smooth, dorsally and laterally covered with dense well-defined minute spiculae, resulting in a velvety appearance of the skin; ventrally smooth to areolate; (10) vertebral column conspicuous, neural processes absent; (11) in life: dorsum black with few yellow-green asymmetric circles, dots or lines; dorsolaterally yellow-green foam-like reticulation forming a band from above eye to groin with numerous black dorsolaterally yellow-green foam-like reticulation forming a band from above eye to groin with numerous black rounded irregular spots (smaller than EYDM); laterally a black band present from tip of snout almost to groin, rarely interrupted by yellow-green lines; limbs and dorsal surfaces of hand and foot with yellow-green foam-like reticulation with black spots (smaller or larger than EYDM), thumb and sometimes tips of fingers and toes dorsally orange to vermillion red; in males, throat and venter cream, posteriorly becoming yellowish, sometimes with few tiny black dots (smaller than or equal to diameter of finger III) on throat and black dots (smaller than EYDM) on lateral and posterior vent; in females, throat and venter yellow with numerous black dots (smaller or larger than EYDM); in both sexes, palms, plants and an ovally-shaped blotch on ventral surface of cloaca and adjacent areas of thighs vermillion red, the latter being surrounded by black dots (smaller than EYDM); iris black with a golden yellow ring surrounding horizontally oriented pupil (12) in preservative: above dark brown background color with cream pattern, below whitish cream with brown dots; vermillion red life markings faded to pale orange, yellow or cream; (13) pulsed call 2,049 ± 220 ms at dominant frequency 2,848 ± 14 Hz .

Diagnosis. Atelopus colomai ( Figs. 12–13 View FIGURE 12 View FIGURE 13 ) can be readily distinguished from all other Atelopus (as far known) by molecular genetics, with an uncorrected p-distance of the 16S rRNA fragment of 1.72% to its closest known described relatives, A. franciscus Lescure and the A. hoogmoedi Lescure complex (Appendices 8, 9). It can be morphologically distinguished from all congeners by the combination of small size, dorsal and lateral skin covered with dense well-defined minute spiculae, ventral skin smooth to slightly areolate, presence of a columella and dorsal pattern, except from A. spumarius Cope sensu stricto, A. histrionicus sp. nov. and A. manauensis Jorge, Ferrão and Lima. From these species, it differs in call duration (2,049 ± 220 ms vs. 922 ± 24 ms in A. spumarius sensu stricto; 807 ± 80 ms in A. histrionicus sp. nov.; 744 ± 84 ms in A. manauensis ; Jorge et al. 2020b), in female ventral coloration and pattern in life (yellow with equally distributed black rounded dots on vent smaller or larger than EYDM vs. throat and chest orange or yellow, venter anteriorly cream yellow, posteriorly orange or yellow, anteriorly with numerous brown or black dots smaller than or equal to EYDM, sometimes forming a continuous band on chest in A. spumarius sensu stricto; whitish to cream with larger rounded or oval dark brown markings in the gular region, on chest and venter in A. histrionicus sp. nov.; venter white or whitish cream with spots in A. manauensis ; Jorge et al. 2020b) and in having in life an oval vermillion red blotch surrounded by small black dots on ventral surface of cloaca and onto adjacent thighs (vs. ventral surface of cloaca and thighs bright orange in A. spumarius sensu stricto, and bright red in A. histrionicus sp. nov. and A. manauensis , all lacking black dots). Further, A. colomai differs from these taxa in having a more pointed, acuminate snout in lateral view in females (vs. subacuminate to truncate and less protruding in A. spumarius sensu stricto; less protruding in A. histrionicus sp. nov.; blunt in A. manauensis ). Moreover, from A. manauensis , A. colomai differs in having a longer head (males HLSQ/HDWD 1.144 ± 0.067, N = 6, vs. 1.054 in A. manauensis , N = 11; Jorge et al. 2020b). The tadpole of A. colomai differs from that of A. manauensis by having the lower about twice as long as the upper beak (vs. upper beak only slightly shorter than lower; Plewnia et al. 2024b).

Atelopus colomai ( Figs. 12–13 View FIGURE 12 View FIGURE 13 ) is similar to its congeners of the flavescens-spumarius clade, to A. andinus Rivero , A. loettersi De la Riva, Castroviejo-Fisher, Chaparro, Boistel and Padial , and the A. tricolor Boulenger complex (including the junior synonyms A. rugulosus Noble and A. willimani Donoso-Barros ) from the eastern Andean versant of Peru and Bolivia, and to A. palmatus Anderson and A. planispina Jiménez de la Espada from the eastern Andean versant of Ecuador. It differs from the nominal A. barbotini Lescure , A. flavescens Duméril and Bibron (including its junior synonym A. vermiculatus McDiarmid ), A. franciscus and the A. hoogmoedi Lescure complex (including the available name A. hoogmoedi nassaui Ouboter and Jairam ) in pattern and coloration in life (dorsally black with few yellow-green asymmetric circles, dots or lines; dorsolaterally yellow-green foam-like reticulation forming a band from above eye to groin with numerous black rounded irregular spots; males below cream, posteriorly becoming yellowish, sometimes with few tiny black dots and a vermillion red shaped blotch on ventral surface of cloaca and adjacent areas of thighs, females below yellow with numerous black dots and a vermillion red shaped blotch on ventral surface of cloaca and adjacent areas of thighs vs. dorsally black with red to pink markings, ventrally reddish pink in A. barbotini ; dorsally unicolored reddish, brownish or yellow or brown and with olive, brownish reddish and copper-like vermiculation, ventrally reddish pink in males, pink in females in A. flavescens ; dorsally olive to blackish brown, ventrally reddish in A. franciscus ; dorsally dark brown or black with yellow, pink, bluish, white, greenish or orange irregular spots and reticulated dorsolateral bands or solid bars, ventrally yellow, pink, bluish, white, greenish or orange, in some specimens with dark spots or blotches in the A. hoogmoedi complex). All these forms, except some populations of the A. hoogmoedi complex, lack red palmar and plantar surfaces in life (present in A. colomai ). All Guianan harlequin frogs have shorter call duration (2,049 ± 220 ms vs. 1,490 ± 140 ms in A. barbotini ; 1,530 ± 220 ms in A. flavescens ; 1,490 ±150 ms in A. franciscus ; 1,190 ± 10 ms in the A. hoogmoedi complex from French Guiana; 1,160 ± 390 ms in the A. hoogmoedi complex from Amapá, Brazil; 1,060 –1,240 ms in the A. hoogmoedi complex from Pará, Brazil; Lescure 1981; Cocroft et al. 1990; Costa-Campos & Carvalho 2018). Tadpoles of A. colomai differ from those of A. flavescens , A. franciscus and the A. hoogmoedi complex in having the lower about twice as long as the upper beak (vs. upper beak only slightly shorter than lower; Plewnia et al. 2024b) and in coloration in life (black to dark brown with dense irregular pale brown to golden markings that consist of aggregated minute dots vs. black with symmetrical golden spots anterior and posterior eye, at the base of the tail and on tail fin in A. flavescens and A. franciscus ; below entirely translucent with few whitish cream dots in the A. hoogmoedi complex; Boistel et al. 2005; Lötters et al. 2022). Atelopus colomai can be distinguished from A. pulcher Boulenger by smaller male SVL (23.2 ± 1.46, N = 6, vs. 27.27 ± 1.07, N = 13, in A. pulcher ; Lötters et al. 2002a), female ventral coloration in life (yellow with numerous black dots and a vermillion red shaped blotch on ventral surface of cloaca and adjacent areas of thighs vs. vermillion red with irregular dark spots in A. pulcher ; Lötters et al. 2002a) and longer calls (2,049 ± 220 ms vs. 1,200 ± 100 ms in A. pulcher ; Lötters et al. 2002a). Tadpoles of A. colomai differ from those of A. pulcher in having the lower about twice as long as the upper beak (vs. one third to one fourth as long) and the nostrils positioned at about height of eye (vs. below height of eye; Plewnia et al. 2024b). Atelopus colomai differs from A. harlequin sp. nov. in larger male SVL (23.2 ± 1.46, N = 6, vs. 20.6 ± 0.51, N = 4, in A. harlequin sp. nov.) and in dorsal coloration and pattern in life (black with yellow-green reticulation vs. dark brown, with yellowish gold circles or lines, sometimes forming a continuous dense reticulation pattern on dorsum, fused with dorsolateral broad band of yellowish golden reticulation in A. harlequin sp. nov.). In addition, it differs from A. harlequin sp. nov. in having longer calls (2,049 ± 220 ms vs. 680 ± 30 ms in A. harlequin sp. nov.; Asquith & Altig 1987). Atelopus colomai differs from A. seminiferus Cope in smaller female SVL (29.8 ± 2.05, N = 10, vs. 40.0, N = 1), absence of lateral warts (present in A. seminiferus ) and dorsal coloration in preservative (dorsally black with few yellowish cream asymmetric circles, dots or lines; dorsolaterally yellowish cream foam-like reticulation forming a band from above eye to groin with numerous black rounded irregular spots vs. dark brown without pattern in A. seminiferus ). From A. andinus , A. loettersi and the A. tricolor complex, A. colomai is distinguished by the presence of a columella (vs. absence; Lötters et al. 2011; authors’ unpubl. data). From A. loettersi , it can be distinguished by female ventral coloration and pattern in life (yellow with numerous black dots and a vermillion red shaped blotch on ventral surface of cloaca and adjacent areas of thighs vs. mostly red, in some specimens with irregular brown blotches in A. loettersi ; De la Riva et al. 2011). Atelopus colomai can be distinguished from A. andinus and the A. tricolor complex by the absence of warts (vs. presence) and by presence of dorsolateral reticulation (vs. absence). Tadpoles of A. colomai differ from those of the A. tricolor complex in having the upper beak shorter than the lower (vs. longer; Plewnia et al. 2024b). Atelopus colomai can be distinguished from A. palmatus and A. planispina by coloration and pattern in life (dorsally black with few yellow-green asymmetric circles, dots or lines; dorsolaterally yellow-green foam-like reticulation forming a band from above eye to groin with numerous black rounded irregular spots; males below cream, posteriorly becoming yellowish, sometimes with few tiny black dots and a vermillion red ovally-shaped blotch on ventral surface of cloaca and adjacent areas of thighs, females below yellow with numerous black dots and a vermillion red ovally-shaped blotch on ventral surface of cloaca and adjacent areas of thighs vs. green blotches on reddish brown dorsum, absence of reticulation; ventrally unicolored orange in females of A. palmatus and whitish to reddish in A. planispina ; Peters 1973) and skin texture (smooth, covered in minute spiculae vs. presence of small spiculae on flanks, upper arm and from eye fading towards groin; Peters 1973). Tadpoles of A. colomai differ from those of A. palmatus in having golden tail pattern in life (vs. absence) and in having the upper beak shorter than the lower (vs. longer; Plewnia et al. 2024b).

Description of holotype. Adult male. Body slender (SW/SVL = 0.265); head slightly longer than wide (HLSQ/ HDWD = 1.103); snout protruding beyond apex of lower jaw, acuminate in dorsal view, forming a triangle from nostrils to tip of snout; nostrils directed laterally, moderately protuberant, not visible in dorsal view, about two thirds from eye to tip of snout in lateral view, situated anterior to apex of lower jaw; canthus rostralis well defined, concave in dorsal view between eye and nostril; loreal region concave; lips not flared; top of snout depressed; head plain in lateral view; eyelid flared, densely covered in minute spiculae; tympanic membrane absent, tympanic annulus not visible; supratympanic crest poorly developed; choanae small, rounded; ostia pharyngea present; tongue about twice as long as wide, broadest at its tip (situated posteriorly); vocal slits present; limbs long and slender (TIBL/ SVL = 0.446); webbing absent on hand; fingers and toes lack lateral fringes; palmar tubercle rounded, poorly developed; supernumerary palmar and plantar tubercles absent; thenar and subarticular tubercles indistinct; tips of digits rounded; phalangeal formula of hand 1-2-3-3; first finger short (THBL/HAND = 0.431), dorsally covered with keratinized dark brown spiculae forming the nuptial pad; inner metatarsal tubercle indistinct, outer metatarsal tubercle rounded, poorly developed; relative length of toes I<II<III<V<IV; phalangeal formula of foot 2-2-3-4-3, webbing formula of toes I 0–0 II 0–1 III 1 / 2 –3 IV 3– 1 / 2 V; tarsal fold absent; foot roughly three quarters of tibia; skin smooth on entire body, dorsally and laterally covered with dense, well-defined minute spiculae, resulting in a velvety appearance of the skin; skin smooth to slightly areolate on ventral surfaces of cloaca and adjacent areas of thighs, venter and throat; cloacal opening in an inconspicuous tube, directed posteriorly; vertebral column visible through the skin, neural processes absent.

In life ( Fig. 13 View FIGURE 13 ), dorsum black with few yellow-green asymmetric circles, dots or lines; dorsolaterally yellow-green foam-like reticulation, forming a band from above eye to groin bearing numerous black rounded markings (smaller than EYDM); lips bordered by thin black line; laterally a black band from tip of snout almost to groin; ventrolaterally transition from yellow-green reticulation with numerous black dots to unicolored cream throat and venter; throat and venter cream with few minute dark dots in gular region (smaller than or equal to diameter of finger III), venter posteriorly becoming yellowish with few black dots (smaller than EYDM); limbs dorsally black, covered in yellow-green bands, ventrally cream to yellow bearing black dots or bars; thumb and tips of fingers and toes dorsally orange to vermillion red; palms, plants and an ovally-shaped blotch on ventral surface of cloaca and adjacent areas of thighs vermillion red, the latter being surrounded by black dots; iris black with a golden yellow ring surrounding horizontally oriented pupil.

In preservative, above blackish brown with yellowish cream pattern; below whitish cream with blackish brown dots; vermillion red life markings faded to pale cream with pale reddish remnants. Proximal (anterior) half of tongue has black pigmentation.

Measurements: SVL 22.3, TIBL 9.9, FOOT 7.5, HLSQ 7.4, IOD 2.3, HDWD 6.7, EYDM 2.7, EYNO 1.9, ITNA 2.0, FAL 7.7, HAND 5.1, THBL 2.2, SW 5.9.

Variation. For meristic variation of characters see Table 4. Paratypes correspond to the description above. However, specimens from Reserva Otoyacu and Río Villano are slightly larger than topotypic individuals and specimens from NW El Triunfo. Among the paratypes is one malformed specimen ( CJ 12197 ) with partial anophthalmia, in which the right eye is not fully developed and almost completely covered with skin .

Sexual dimorphism is apparent in A. colomai with females being larger than males (SVL: 29.8 ± 2.05, N = 10, vs. 23.2 ± 1.46, N = 6). In addition, females lack nuptial pads and vocal slits, differ in coloration by having a yellow venter with equally distributed rounded black dots (smaller or larger than EYDM) in the gular region, on chest and venter ( Fig. 13 View FIGURE 13 ).

Skull osteology. General osteological features of a male (CJ 8187; MorphoSource Media ID 000077646) and a female (CJ 8188, paratype; MorphoSource Media ID 000077646) are depicted in Figures 5–6 View FIGURE 5 View FIGURE 6 and Appendix 4. The skull of A. colomai is triangular in dorsal view. The skull length is 8.5, the skull width is 8.1, and the skull height is 5.4 in CJ 8187; the skull length is 8.8, the skull width is 7.8, and the skull height is 5.2 in CJ 8188. The skull roof is smooth. In anterior view, the septomaxilla is U-shaped with medial and lateral rami that extend posteriorly towards the vomer. The lateral ramus is much broader than the medial ramus and bears a nasal process. The ossified sphenethmoid is smooth and underlies the posterior and medial margins of nasals, as well as the anterior and anterolateral margins of the frontoparietals. The posterior limit of the sphenethmoid is about one-third the length of the margin of the orbit. The prootics are fused to posterolateral edge of the frontoparietals. The exoccipitals encircle the foramen magnum and are fused to the frontoparietals dorsally, the prootics laterally, and the parasphenoid anteroventrally. The otic capsule is well-ossified. Columellae are present, cylindrical in shape. The pars media of the columella is slender and slightly bowed, and the pars interna is not ossified. The operculum in the fenestra ovalis is mineralized and visible. The nasals are triangular and bear an acuminate maxillary process that extends ventrolaterally toward the maxilla and contacts the pars facialis of the maxilla in CJ 8187 and nearly contacts the pars facialis of the maxilla in CJ 8188. The nasals are moderately separated medially. The frontoparietals are rectangular and the orbital edges are straight. Medial articulation is complete in both specimens. A suture line is visible only in CJ 8188. A supraorbital flange is absent. Occipital groves, which are canals for the carotid artery, are present and partially roofed with bone. In both specimens, the grooves are covered along the midpoint but open at the anterior and posterior tips. Posteriorly, the frontoparietals are fused to the prootics and exoccipitals. The vomers are small, edentate, medially separated, crescent-shaped, and triradiate with an anterior ramus, prechoanal ramus, and postchoanal ramus. The anterior ramus is directed anterolaterally, pointed at the anterior tip, and is roughly the same size as the pre- and postchoanal ramus. The pre- and postchoanal rami form the anteromedial margin of the choana. The prechoanal ramus is directed towards the maxilla, and the postchoanal ramus is directed posterolaterally. The postchoanal ramus is fused to the overlying sphenethmoid. The neopalatine is elongate and triangular. It underlies, and is partially fused to, the sphenethmoid and extends towards the maxilla, nearly making contact with the preorbital process in CJ 8188 and making contact in CJ 8187. The neopalatine is narrow and pointed at its medial tip, widens as it approaches the maxilla, and is cylindrical and pointed at its anterior border. The parasphenoid has an inverted T-shape and the cultriform process underlies the sphenethmoid in CJ 8188 (but does not in CJ 8187). The cultriform process extends beyond the midpoint of the orbit. The terminal end of the cultriform process is rounded in shape. The parasphenoid alae are directed posterolateral to the cultriform process and are fused to the overlying otic capsule. The posterior margin of the parasphenoid and a medial posterior process are difficult to discern. The maxillary arcade is complete and edentate. The paired premaxillae each possess a dorsal alary process that is directed anterolaterally. The lower half of the alary process is the same width as the upper half. The pars palatina is biradiate with medial and lateral processes. The lateral process is more than twice as long as the medial process. The medial process is well developed and triangular. A concave border is present where the lateral and medial processes of the pars palatina come together. The posterior tip of the pars dentalis is pointed and articulates with the maxilla. The external surface of the maxillae is smooth. The pars palatina, which extend along the lingual margin of the maxilla, is narrow, and the posterior half of this shelf articulates with the anterior ramus of the pterygoid. The pars fascialis of the maxilla is directed; its dorsomedial margin variably contacts, or nearly contacts, the neopalatine, sphenethmoid, and maxillary process of the nasal. The anterior end of the maxilla is truncate and contacts the premaxilla. The posterior end of the maxilla is pointed and slightly overlaps the quadratojugal. The quadratojugal is a small, slender, L-shaped bone that underlies the ventral arm of the squamosal and contacts the posterior process of the maxilla at is anterior margin. The paired squamosals possess an otic ramus posterodorsally and a ventral ramus. An anterodorsal zygomatic ramus is not evident. The otic ramus is expanded dorsally and has a broad articulation with the crista parotica of the otic capsule, leaving only the posterior end of the prootic free. The angle between the dorsal surface of the squamosal and the anterior margin of the ventral ramus is nearly perpendicular. The ventral ramus is flat and blade-like. A small squamosal keel is present at the junction between the otic ramus and the upper half of the ventral arm. The pterygoid is triradiate, bearing anterior, medial, and posterior rami. The anterior ramus articulates with the pars palatina of the maxilla. The medial and posterior rami are of equal length but the medial ramus is much broader. The medial ramus nearly contacts the prootic. The posterior ramus is flat and blade-like. The palatoquadrate is cartilaginous and therefore not visible in the microCT dataset. The lower jaw is composed of three ossified elements and Meckel’s cartilage, which is not visible in the microCT dataset. The mentomeckelian is the most anterior element that forms a cartilaginous symphysis at the midline of the jaws. Posterodorsally, the mentomeckelian is fused to the dentary. The dentary is slender, thin, and edentate; this element overlays the anterior half of the angulosplenial. The angulosplenial is the largest mandible element and forms the lingual surface of the lower jaws. The lower jaw length is 7.1 in CJ 8187 and 7.3 in CJ 8188, slightly shorter than the length as the skull from the occipital condyle to the premaxilla.

Atelopus colomai can be distinguished from the species (re)described herein by its smooth skull roof (vs. rugose; Fig. 5 View FIGURE 5 ), having the frontoparietals completely fused (vs. fused only over two posterior thirds of their total length; Fig. 6 View FIGURE 6 ).

Further, A. colomai differs from the neotype of A. spumarius sensu stricto by the posterior end of the maxilla not being free (vs. free), the pars glenoidalis and the pars jugularis of the quadratojugal being subrectangular and elongated, respectively (vs. pars glenoidalis thickend, pars jugularis short), and a less straight orbital margin of the maxilla. However, variation in these characters exists between the two populations of A. spumarius sensu stricto, which might be attributed to imaging conditions or natural variation. Atelopus colomai can be distinguished from A. harlequin sp. nov. by the distal end of the otic ramus of the squamosal being free (vs. medial side of the posterodorsal process of the squamosal attached along its entire length to the prootic) and the frontoparietals dorsally being less convex. Atelopus colomai differs from A. histrionicus sp. nov. by having less straight lateral margins corresponding to the maxilla, having a less deep posteroventral incisure of the sphenethmoid, and having a slightly recessed dorsal end of the premaxillary process (= pars facialis) (vs. process protruding anteriorly beyond the anterior limit of the nasals). For details see Figures 5–6 View FIGURE 5 View FIGURE 6 and Appendix 4.

However, the discriminatory power of osteological features needs to be seen with caution as intraspecific variation, sexual dimorphism and taxonomic value remain poorly understood for the species discussed.

Vocalization. Calls were recorded by AP from the life holotype in the laboratory on 26 September 2021, ca. 06:00 pm, with a Sennheiser ME 66 directional microphone attached to an Olympus Digital Voice Recorder DM-901. Distance to recorder was 0.6 m and ambient temperature was ca. 23°C. A 60,512 ms recording was available for analysis ( CJ ec.cj.aud.19; Fonozoo Sound Code 14651; Fig. 14 View FIGURE 14 ). It consists of 11 pulsed calls with duration 2,049 ± 220 ms (1,747 –2,488 ms). Intervals between calls last 3,601 ± 1,791 ms (1,791 –6,928 ms). Dominant frequency is 2,848 ± 14 Hz (2,821 –2,877 Hz). Amplitude is generally ascending over the course of the call being interrupted by 2–4 local decreases until it reaches its maximum followed by a subsequent decrease over the last 3–10 pulses. Frequency shows harmonics and is weakly modulated with a minimal increase towards the end of the call. Each call consists of 52 ± 6 pulses (42–60), that show a length of 7 ± 2 ms (3–14 ms) each. Pulses slightly increase in length over the course of each call and are not modulated in frequency GoogleMaps .

Tadpole. The tadpole was described by Duellman & Lynch (1969); it was redescribed and compared to larvae of other species by Plewnia et al. (2024b).

Distribution. Atelopus colomai is known from the Amazonian lowlands of Ecuador, ranging from ca. 240– 1,020 m asl. Historically, A. colomai was reported from less than 30 localities in Orellana and Pastaza Provinces, all situated between Río Napo and Río Pastaza ( Fig. 2 View FIGURE 2 ). However, specimens collected by Rolf Blomberg in 1937 (NHRM RRB/1937.809.3262) originate from “Zamora”, which, by that time, was the name for large parts of the southern Ecuadorian and adjacent Peruvian Amazonian lowlands. Thus, the distributional limits south- and eastward remain uncertain. Throughout the last 20 years and despite intensive efforts to locate the species, A. colomai was confirmed only in few localities in Pastaza Province, NE and SE of Puyo.

Natural history. The species inhabits terra firme lowland rain forest and can be found in close proximity to slow-moving clear water streams and rivers ( Fig. 15 View FIGURE 15 ). Adult males can be heard calling throughout the day with an activity peak after rainfalls, in the morning and late afternoon as observed in August and September. Reproductive males defend territories along the streams where entering males are approached by the resident and pursued, accompanied by intense calling observed in the same months. Territorial behavior was also observed by Tarvin et al. (2014). Males were found perching on elevated positions such as branches, fallen trees and rocks in the lower understory up to 1.5 m above ground during the day. At night, males were inactive, resting on leaves up to 2 m above ground. Females were found at night only, sleeping on leaves or in bromeliad axils 1–5 m above ground. At the type locality, amplectant pairs were observed in March, April, July–October and December ( Tarvin et al. 2014; authors’ observations). Tadpoles were collected in July ( Duellman & Lynch 1969) and metamorphs were observed in September suggesting that reproduction may take place year-round.

Atelopus colomai can be locally abundant reaching densities of up to 21 individuals per person*hour in nocturnal visual encounter surveys at the type locality in September 2022. NW of El Triunfo, where some of the paratypes were collected, the species is less common with 5 individuals found in approx. 20 person*hours in 2021. Tarvin et al. (2014) observed 356 individually identified specimens through the course of a two-year capture-recapture study in a population along Río Pucayacu, close to the type locality. For information on syntopic anurans at the type locality see Culebras et al. (2023). Monitoring studies conducted between 1994 and 2012 in Yasuní National Park ( Read 2018) identified this species as rare. Only five individuals were discovered at two locations within the park.

When disturbed, A. colomai present their colorful palms and soles while slowly walking away ( Plewnia et al. 2024a: Supplementary Video), similar to congeners from eastern Amazonia as described by Rössler et al. (2019). During handling, specimens sometimes show an “unkenreflex” ( Fig. 16 View FIGURE 16 ).

Conservation status. Plewnia et al. (2024b) suggested listing A. colomai as Endangered under criteria B1 and B2a, b of the IUCN Red List of Threatened Species. Including historic localities, the EOO of A. colomai is roughly 7,470 km ² and AOO 64 km ² while it is 172 km ² and 24 km ² for extant localities only.

According to Plewnia et al. (2024b), the type locality, an almost complete deforestation of remaining habitats occurred in late 2022 ( Fig. 17 View FIGURE 17 ). Fieldwork in August 2023 revealed the presence of few individuals in a remaining 10 m wide fragment of forest along one side of the stream. Deforestation has also been concluded as the reason for declines in another population of A. colomai by Tarvin et al. (2014). In the remaining four sites, there is a constant reduction in the extent and quality of remaining habitat. The species is known from one private protected area, Reserva Otoyacu, and was formerly found in Parque Nacional Yasuní from where it has not been confirmed in more than 20 years.

Bd, considered a main driver of extinctions in Atelopus (e.g. La Marca et al. 2005; Lips et al. 2008; Lötters et al. 2023), has been repeatedly detected in A. colomai ( Lötters et al. 2023) . However, no declines related to Bd were noticed, similar to other lowland Atelopus species ( Flechas et al. 2012, 2015; Ballestas et al. 2021). Tarvin et al. (2014) conducted a comprehensive Bd sampling, documenting the pathogens’ absence in Atelopus but its presence in syntopic anurans in their study site. In September 2021, we found Bd both in Atelopus and syntopic anurans at the type locality (prevalence 27.4 %, CI 9.7–51.5 %). In the same population, we sampled Atelopus only again in September 2022, revealing that Bd was still present (prevalence 24.8 %, CI 11.6–41.3 %). At a locality where A. colomai has apparently declined, we found Bd in syntopic anurans only in 2021 (prevalence 24.6 %, CI 7.7–48.3 %; Appendix 5), and at another site where population status is unknown, Bd was present as well (prevalence 23.0 %, CI 4.5–50.1 %) with as much as> 20,000 GE in one frog. The pathogen was not present in a locality SE Puyo (although sample size might have been too small).

Atelopus colomai is further likely to be threatened by climate change in the near future, which might both impact the species habitat as well as interfer and exacerbate existing threats such as disease ( Lötters et al. 2023). The species from the western Amazon are among the harlequin frogs likely to be most affected by climate change ( Lötters et al. 2023).

This species is currently kept in a laboratory survival-assurance colony in CJ, where it has already been bred successfully in F1 generation. A backup colony is held at Centro de Conservación de Anfibios, Bioparque Amaru, Cuenca.

Etymology. The species has been dedicated to the Ecuadorian herpetologist Luis A. Coloma, for his unparalleled contribution to the study and protection of the harlequin frogs in Ecuador. The name is a noun in genitive case, singular ( Plewnia et al. 2024b).

Remarks. Paratypes CJ 12406, 12409, 12425 remain alive as founders of a laboratory survival-assurance colony; they are illustrated in Plewnia et al. (2024b).