A New Species of Armored Catfish (Loricariidae: Hypoptopomatinae) Syntopic and Superficially Similar to Parotocinclus collinsae, from the Potaro River Basin, Guyana
Parotocinclus hardmani, new species, is described as a new hypoptopomatine from tributaries of the Potaro River, Essequibo River basin, Potaro-Siparuni, Guyana. The new species is distinguished from congeners in northeastern and southeastern coastal rivers of Brazil by having the canal cheek plate elongated posteriorly on the ventral surface of the head and in contact with the cleithrum. It is diagnosed from species of Parotocinclus from the Amazon, Orinoco, and Guianas watersheds by uniquely having a conspicuously elongated, conical urogenital papilla which is twice the size of the anal tube and 3–4 times larger than in congeners, by having the central abdominal area mostly devoid of plates, by mature males lacking a dermal flap on the dorsal surface of the first pelvic-fin ray, and, except for P. halbothi, by having a rudimentary adipose fin adnate to the dorsal plates, without a membrane. The new species is believed to form a clade with P. collinsae and P. halbothi, with which it shares accessory teeth on both premaxilla and dentary, the odontodes on the first pelvic-fin ray aligned with the main ray axis, not bent and pointing mesially, the lack of a triangular dark spot at the anterior base of the dorsal fin, and the lack of a Y-shaped light mark from the snout tip to each nostril.
Holotype of Parotocinclus hardmani, CSBD F3618, 22.8 mm SL, female, Kuribrong River at Grass Shoals Rapids, Potaro-Siparuni, Guyana.
Parotocinclus hardmani, ROM 91423, CT scan of head in dorsal, lateral, and ventral views. Note typical snout shape, canal cheek plate extended posteriorly and contacting pectoral girdle, and absence of central abdominal plates. Scale bar = 1 mm.
Pelvic region of Parotocinclus. (A) P. hardmani, MCP 54588, 20.4 mm SL; and (B) P. collinsae, AUM 62851, 21.7 mm SL. ap1, exposed portion of first anal-fin pterygiophore; at, anal tube; pap, preanal plate; ugp, urogenital papilla. Scale bar = 1 mm.
Parotocinclus collinsae, AMNH 55433, holotype, 23.9 mm SL, male, creek tributary to Takutu River, about 2 miles from Mazarahally Takutu lumber camp in Takutu Mountains, Essequibo River drainage, Cuyuni-Mazaruni, Guyana.
Parotocinclus hardmani, ROM 91423, CT scan of the jaw bones in dorsal view; aa, anguloarticular; ath, accessory teeth; d, dentary; mx, maxilla; pmx, pramaxilla. Scale bar = 1 mm.
Drainage map centered on Guyana showing the localities of Parotocinclus hardmani (white circle) and examined specimens of P. collinsae (black circle). Black and white circles indicate syntopy of the species. T indicates type-locality; each symbol may represent more than one lot or locality.
Contributor Notes
Associate Editor: W. L. Smith.