taxonID	type	description	language	source
03CF87D4FF9C0E5EFE84484A6F2EEACD.taxon	description	Description: Shell thin, small (maximum observed size = 3.3 mm), ovate, moderately high (I H / L = 85 ± 2, n = 10; inflated (Ci = 78 ± 4, n = 10), inequilateral, anterior end protruded in a sharp curve, posterior end short, rounded, truncate. Beaks moderately full, posteriorly displaced, located at 58 ± 2 % of shell length (Fig. 1 A, B, E). Posterior half of dorsal margin slightly arcuate, nearly straight at anterior half. The points of connection of dorsal margin with anterior and posterior margins slightly marked by an angle. Hinge plate narrow, hinge line relatively long (Hil represents about 58 % of L). Hinge: left valve: inner left cardinal tooth (C 2) short, strong; outer left cardinal (C 4) extremely thin, long, faintly curved, overlapping C 2 at least at the posterior half. Left lateral teeth (A 2, P 2) well developed, strong but low (Fig. 1 D). Right cardinal tooth (C 3) weak, anterior half straight, posterior end enlarged and slightly sulcated. Anterior right laterals just below the angle between anterior and dorsal margins, outer anterior (A 3) and outer posterior (P 3) lateral teeth strongly reduced in size, with distal cusps (Fig. 1 F). Ligament pit enclosed, slender. Ligament internal, long, representing about 23 % of L, visible from the exterior through an elongate and quite slender gap, but never protruding. Escutcheon obscure, marked by a delicate line, slightly elevated directly over the ligament (Fig. 1 C). Shell surface sculptured with low, regularly spaced commarginal striae. Anatomy: Mantle: only the anal siphon present. Pedal slit shortened, its posterior region corresponds to the branchial opening. Two well developed pairs of siphonal retractor muscles, the lower ones, relatively long, correspond to the retractor muscles of the branchial opening (present in species of Pisidium s. s). Inner radial mantle muscles well developed, rather strong and concentrated, bundles reduced in number (5 to 6) and evenly arranged (Fig. 2 A, B). Muscle scars obscure, separate from the mantle line, particularly the anterior scars (Fig. 2 C). Gill: Outer demibranch absent. Developing brood pouch in upper position, including 12 to 18 filaments. Number of embryos ranged from 8 to 22 (Fig. 2 D). Nephridium: Of the closed type (pericardial duct completely covered by the dorsal lobe of nephridium). Dorsal lobe triangular in smaller specimens, rectangular in larger ones. Lateral loop easily visible (Fig. 2 E – F).	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF9C0E5EFE84484A6F2EEACD.taxon	discussion	Remarks: Pisidium dorbignyi resembles Pisidium vile Pilsbry, 1897, consistently differing in having a lower and more ovate shell outline (not necessary reflected in the morphometric indices which are similar). Pisidium dorbignyi has a flatter shell with less projecting beaks, which are comparatively more displaced posteriorly. Compared with Pisidium sterkianum Pilsbry, 1897, P. dorbignyi is much smaller and comparatively higher, differing also in having an internal ligament and more concentrated bundles of the inner radial mantle muscles (possibly associated with reduced size, in particular, of the shell length). Note on the types: As it has been previously reported by Pilsbry (1897), the type of Cyclas pulchella (= Pisidium dorbignyi) was not among d' Orbigny's shells acquired by the Natural History Museum, London. F. Naggs (personal communication, April 1997) confirmed this. In fact, C. pulchella was included in the Gray’s list (Gray, 1854) of d´Orbigny's South American shells acquired by the British Museum of Natural History, London, but the record is not marked with the acronym “ BM ”, as other specimens received from d´Orbigny. This is also in agreement with the registration book to the BMNH mollusks collection, where no entry for C. pulchella can be found. Neither has the type of C. pulchella been found at the MNHN, Paris (P. Bouchet, personal communication), so it should to be considered lost. In order to define the taxonomic status of Pisidium dorbignyi, a neotype is here selected and housed in the mollusk collection of MHNM 15544, Montevideo, Uruguay.	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF9C0E5EFE84484A6F2EEACD.taxon	materials_examined	Type locality: The neotype was selected from a sample taken from an unnamed water course on the road from Maldonado to San Carlos City (34 ° 48 ' S, 54 ° 55 ' W), Maldonado Department, Uruguay (a site in the vicinity of the type locality of Cyclas pulchella). Other examined material: Uruguay: same locality of neotype (MLP 10497); artificial rice-fields irrigation channels at San Gregorio, Artigas Department, Uruguay (3 specimens dissected) (MLP 5296).	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF9C0E5EFE84484A6F2EEACD.taxon	distribution	Distribution: Uruguay: water courses connected with the Uruguay River at Artigas Department and coastal lagoons and small streams at Maldonado Department. The records of Pisidium dorbignyi reported from the Río de La Plata and related water courses at Buenos Aires Province (Landoni, 1992) are doubtful (Ituarte, 1996). The species was also reported from northern Brazil (Lange de Morretes, 1954 fide Figueiras, 1965), but this record needs to be confirmed.	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF990E5CFE844BB36E69E875.taxon	description	Description: Shell oval, high (I H / L = 85 ± 2), medium to large size (maximum observed L = 5.35 mm), not inflated (Ci = 59 ± 5). Dorsal and ventral margins markedly curved, the anterior margin slopes evenly to the anterior end, which is slightly projected. Posterior end short, rounded, somewhat oblique in adults, markedly truncated in smaller specimens (Fig. 3 A, C). Beaks wide at base, very low, slightly projected over dorsal margin, located at 57 ± 1.4 % of L (Fig. 3 A, C). Hinge plate moderately strong, hinge line short (Hil / L = 53 ± 5) and markedly curve. Ligament pit enclosed, short, deep; ligament internal, long (Li = 21 ± 2), not visible from exterior except from a quite slender gap. Hinge: left valve: cardinal teeth thin, the outer (C 4) overlapping C 2 at the posterior third; anterior (A 2) and posterior (P 2) laterals strong, short, cusps sub-central. Right valve: cardinal tooth (C 3) delicate, anterior end slender, curved, shorter than the posterior end which is slightly expanded in a triangular sulcated cup; anterior and posterior lateral teeth well developed, the inners (A 1 and P 1) solid, long, with slightly displaced cusps; the outer laterals (A 3 and P 3) strong but reduced in size (Fig. 3 B). Anatomy: Mantle: only anal mantle opening present. Inner radial mantle muscles weak; 7 – 8 bundles of few fibres were observed (Fig. 4 A). Scars of the inner radial mantle muscles, slightly visible, merged with or immediately over the pallial line. Nephridium: Lateral loop visible from dorsal view, dorsal lobe of nephridium subquadrangular, proximal part of the nephridium, the pericardial duct, usually not visible (closed type) from dorsal side (Fig. 4 A, B, C right), except in few cases (open type of nephridium) (Fig. 4 C left). Gill: Only inner demibranch present (Fig. 4 A, D). Brood sac developing from descending lamellae in upper position (Fig. 4 D).	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF990E5CFE844BB36E69E875.taxon	materials_examined	Type locality: Punta Arenas (53 ° 9 ' S, 70 ° 55 ' 0 W), Patagonia [Chile]. Material examined: Lectotype, here selected, and, 73 paralectotypes, loose valves, all from the type locality (MNHN, Paris); 7 alcohol preserved specimens from Río de La Mano, Punta Arenas [Chile] (MNHN, Paris).	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF990E5CFE844BB36E69E875.taxon	discussion	Remarks: Pisidium lebruni is easily distinguished from other Patagonian species by its large size, markedly oval shell outline and comparatively flat shell. P. lebruni is similar to Pisidium inacayali Ituarte, 1996 from which it differs in having a more equilateral shell, less projected anterior margin, with a higher shell outline. Both species are similar in soft anatomy. Pisidium llanquihuense Ituarte, 1999, a species from Chilean Patagonia is also a large Pisidium species that differs from P. lebruni by its decidedly sub-quadrangular shell outline. It is to be noted that smaller specimens of P. lebruni (about 3.5 mm length) are remarkably similar in shell outline to Pisidium magellanicum, a species only known from a single, not well preserved left shell, washed into the sea at Beagle Channel near Punta Arenas, Chile, the type locality of P. lebruni. Since Mabille description (Mabille, 1884), Pisidium lebruni was not reported or cited until 1995 (Ituarte, 1995). The MNHN, Paris, houses a alcohol preserved sample whose label reads: “ Río de la Mano [Punta Arenas], Mission Lebrun, 1833 ” that likely corresponds to the same collecting event that the syntypes and was a part of the series upon which P. lebruni was described. Soft anatomy described here was based on these specimens.	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF9B0E52FE8448F869E8EAB5.taxon	description	Description: Shell medium to large (maximum L: 6,1 mm), somewhat high (I H / L = 81.9 ± 1.8), somewhat inflated (Ci = 69.3 ± 5,4) (Fig. 5 B). Shell outline ovate, dorsal margin shorter than ventral margin; ventral margin evenly and widely curved. Anterior end produced, posterior end somewhat truncated. Beaks full, posteriorly displaced (located at about 58 % of shell length) well visible above dorsal margin. Shell surface fine and regularly striated, straw-yellowish (Fig. 5 A, C). Hinge plate not solid, stretching markedly at sides of cardinal teeth. Hinge line widely curve, moderately long (Hil / L = 58 ± 2.7) (Fig. 5 D). Hinge: Right valve: cardinal tooth (C 3) enlarged at posterior end in a slightly sulcated cup; right lateral teeth well developed, the inner anterior (A 1) a long broadly curved lamella, cusp low, sub-central or slightly displaced forward, the outer anterior (A 3) shorter with cusp distal. Posterior lateral teeth (P 1 and P 3) nearly straight. Left valve (Fig. 5 D): inner cardinal tooth (C 2) short, bent upward; outer cardinal (C 4) slightly longer than C 2, slender, evenly arcuate, overlapping C 2 at posterior half. Anterior left lateral strong, high, cusp triangular shifted distally; posterior lateral (P 2) reduced in size, with distal cusp. Ligament external, protruded, representing about 19.7 ± 2.7 % of shell length. Anatomy: Mantle: Only anal mantle opening present. Pedal slit very long, its posterior end correspond to the branchial opening. Two well developed pairs of siphon retractors are noticeable; the upper retractors belonging to the anal siphon (Fig. 6 A, B: sr 1), the lower ones correspond to the region of the branchial opening (lacking in this species) (Fig. 6 A, B: sr 2), the lower retractor fibers are connected with the pre-siphonal suture (Fig. 6 A, B: pss), between the siphon and the pedal slit. Inner radial mantle muscles long but rather thin, weak; posterior fibers converge to the lower siphon retractors, the other fibres form 6 to 7 bundles evenly arranged along the pedal slit. Bundles of the anterior and middle portion of pedal slit are equally developed. Scars of the inner radial muscles are small and usually not clear; when defined, they are separate from the pallial line (Fig. 6 C). Nephridium: Of closed type, the pericardial duct is not visible as it is covered by the dorsal lobe (Fig. 6 E); when viewed from dorsal side the organ is S-shaped because a part of the lateral loop is always visible, dorsal lobe rectangular; in some specimens, a small portion of the pericardial duct is visible from dorsal side (open type of nephridium) (Fig. 6 D). Gill: Only inner demibranch present. Brood pouch developing from thickenings in the dorsal portions of descending filaments (Fig. 6 F). On later stages of development, brood pouch occupies the greatest part of the gill (Fig. 6 G). The number of filaments involved in the formation of the brood pouch depends on the size of the maternal individual, varying from 13 (in a 4.9 mm long specimen) to 20 (in a 5.2 mm length specimen). The number of embryos per brood pouch varied from 7 to 15.	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF9B0E52FE8448F869E8EAB5.taxon	materials_examined	Material examined: Uruguay: Syntypes (ANSP 70490) Arroyo Miguelete, Montevideo (34 ° 51 ' 29 ” S, 56 ° 10 ' 15 ” W); Parque Arequita, Minas (34 ° 22 ' 12 ” S, 55 ° 13 ' 30 ” W), Lavalleja Department (MLP 5343); unnamed brook in the neighbors of Canelones City, Canelones Department (MHNM 5602). Argentina: Miguelín Rivulet, Ensenada, Buenos Aires Province (MLP 5058), 4 specimens dissected.	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF9B0E52FE8448F869E8EAB5.taxon	discussion	Remarks: Pisidium sterkianum is easily identified by having an external ligament, clearly protruded, a unique feature among South American species. This only feature differentiate P. sterkianum from similar species such as Pisidium forense Meier Brook, 1968, Pisidium pipoense Ituarte, 2000 and Pisidium taraguyense Ituarte, 2000.	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF940E50FE844F62693DEACD.taxon	description	Description: Shell small (maximum observed L = 2.85, average = 2.2 ± 0.33), high (I H / L varying among localities between 85 ± 2 and 89.2 ± 2.3), inflated (Ci varying among localities between 79 ± 4 and 82.3 ± 4.6). Beaks wide at base, inflated and high, well visible over dorsal margin, sub-central or slightly displaced posteriorly (located at about 57 – 60 % of L). Shell outline trapezoid, anterior end slightly protruded, posterior end nearly straight, truncated. Dorsal margin short, markedly curve, ventral margin widely curve. Shell surface brilliant, white or yellowish, with somewhat regularly well marked commarginal striae (Fig. 7 A, B, D). Hinge plate solid (Fig. 7 E, F). Hinge line moderately long (Hil / L varying among localities between 56 ± 1.6 and 58 ± 3). Hinge: Left valve (Fig. 7 E): inner cardinal tooth (C 2) robust, with pointed cusp bent upward, outer cardinal (C 4) slender, curved, covering C 2 at posterior end; anterior (A 2) and posterior (P 2) lateral teeth robust with markedly displaced cusps. Right valve (Fig. 7 F): cardinal tooth (C 3) minute, straight at anterior half, enlarged at posterior end in a triangular cup; inner anterior (A 1) and inner posterior (A 1) laterals quite robust, outer lateral teeth (A 3, P 3) reduced in size but strong. Ligament pit enclosed, ligament slender, moderately long (Li = 20 ± 1.4), not visible from exterior. Escutcheon marked by a delicate line, anterior half slightly elevated, over the anterior half of ligament (Fig. 7 C). Anatomy: Mantle: Only the anal mantle opening present, siphon retractor muscles of the same conditions as in Pisidium sterkianum and Pisidium dorbignyi (Fig. 8 A, B). Inner radial mantle muscles forming six strong, well defined, bundles, evenly distributed along the pedal slit. Muscle scars well defined only in anterior part of the shell where they are separate from the mantle line (Fig. 8 C). Gills: Only inner demibranch present. Developing brood pouch occupying the upper part of the inner demibranch, formed by 12 (in a 2.4 mm long specimen) to 17 (in a 2.75 mm long specimen) filaments (Fig. 8 D). Between five and 11 embryos per pouch were found. Nephridium: Of the closed type, with broad and rectangular dorsal lobe (Fig. 8 E, F) and lateral loop visible from dorsal view.	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF940E50FE844F62693DEACD.taxon	materials_examined	Examined material: Uruguay: Syntypes (ANSP 70489), Arroyo Miguelete, Montevideo (34 ° 51 ' 29 ” S, 56 ° 10 ' 15 ” W); Arroyo Miguelete, Montevideo (MLP 5665). Argentina: Arroyo Miguelín, Ensenada (34 ° 52 ' 33 ” S, 57 ° 52 ' 56 ” W), Buenos Aires Province (MLP 5662).	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
03CF87D4FF940E50FE844F62693DEACD.taxon	discussion	Remarks: The high trapezoidal shell outline, the quite solid hinge plate and the reduced size, clearly identifies Pisidium vile and separates it from other small South American species such as Pisidium dorbignyi (with a lower shell outline and less prominent beaks) and Pisidium punctiferum Guppy, 1867 (with a somewhat subquadrangular, flatter shell). It should be noted that the concentration of mantle muscles in Pisidium dorbignyi and Pisidium vile may be associated with smaller size, however, Pisidium punctiferun, a species of comparable or even smaller size, has not less than 8 bundles of inner radial mantle muscles (Korniushin, personal observation).	en	Ituarte, Cristián, Korniushin, Alexei Victor (2006): Anatomical characteristics of two enigmatic and two poorly known Pisidium species (Bivalvia: Sphaeriidae) from Southern South America. Zootaxa 1338: 33-47, DOI: 10.5281/zenodo.174347
