Rhinotocinclus collinsae ( Schmidt & Ferraris, 1985 ), 2022

Reis, Roberto E. & Lehmann A., Pablo, 2022, A new genus of armored catfish (Siluriformes: Loricariidae) from the Greater Amazon, with a review of the species and description of five new species, Neotropical Ichthyology (e 220002) 20 (2), pp. 1-100 : 57-58

Rhinotocinclus collinsae ( Schmidt & Ferraris, 1985) , new combination

( Fig. 31 ; Tab. 6 )

Parotocinclus collinsae Schmidt & Ferraris, 1985:341 (Type-locality: Guyana, Essequibo Province, tributary to [Little] Takutu River about 2 mi from Mazarahally Takutu lumber camp in Takutu Mountains, approx. 06°15’N 59°5’W. Holotype: AMNH 55433).

Diagnosis. Rhinotocinclus collinsae is distinguished from all congeners, except R. halbolthi and R. hardmanni , by having accessory teeth on both premaxilla and dentary (Fig. 5A; accessory teeth absent); the odontodes on the ventral surface of first pelvicfin ray aligned with main ray axis (Fig. 9B; vs. odontodes bent and pointing mesially, Fig. 9A); and lacking a light mark from the snout tip to nostrils (Figs. 6G,H; vs. light mark present and Y-, V-shaped or as two separate lines). Rhinotocinclus collinsae is further distinguished from R. britskii , R. discolor , R. eppleyi , R. isabelae , R. kwarup , R. longirostris, R. pilosus , R. polyochrus , R. variola , and R. yaka by lacking a triangular dark spot on the anterior portion of the dorsal-fin membrane (vs. dorsal-fin spot present); and from R. acuen , R. bockmanni , R. chromodontus , R. dani , R. dinizae , R. hera , R. jumaorum , R. loxochelis n. sp., R. marginalis n. sp., and R. pentakelis by possessing an adipose fin (vs. adipose fin absent). Rhinotocinclus collinsae is distinguished from R. halbolthi and R. hardmanni by having a normally developed adipose fin (Figs. A,B; vs. adipose-fin spine coalesced to the dorsum, Fig. 4C). It is further distinguished from R. halbolthi by having one series of middle abdominal plates (vs. 4–7 series), and a longer pectoral fin (58.2–69.1% vs. 46.3–55.8% HL); and from R. hardmanii by having many and large accessory teeth (vs. few and minute teeth), a normally developed urogenital papilla in males (vs. urogenital papilla 3–4 times bigger than normal), skin flap on first pelvic-fin ray of males (vs. skin flap absent), and belly fully plated between the lateral abdominal plates (vs. belly naked or almost naked between lateral abdominal plates).

Geographical distribution. Rhinotocinclus collinsae occurs in the Essequibo River basin, including the Potaro and Mazaruni rivers, in the Regions of Cuyuni-Mazarui and Potaro-Siparuni of Guyana ( Fig. 32 ).

Remarks. The type-locality of R. collinsae was originally described as “ Guyana, Essequibo Province, tributary to Takutu River about 2 mi from Mazarahally Takutu lumber camp in Takutu Mountains, approx. 06 o 15’N 59 o 05’W, the type specimens being collected by Robert E. Schmidt and Antonios Pappantoniou on 17 August 1983. Despite the approximate coordinates provided suggest the locality is in the lower Mazaruni River, the Takutu River is a well know tributary to the upper Branco of the Amazon basin. Trying to solve this apparent inconsistency, we found a collecting locality of Apistogramma ortmanni at the AMNH collected by the same collector in 1983 (AMNH 72979; field station RES-83-16) that reads: “Little Takutu River and tributaries, Mazarahally Takutu lumber camp, west shore Mazaruni River”. Despite we could not locate this site precisely on a map, it names the river as “Little Takutu”, which differentiates from the Branco tributary Takutu River, and undoubtedly sets the locality in the lower Mazaruni basin. For this reason, the original type-locality of Rhinotocinclus collinsae is herein corrected to Little Takutu River. Rhinotocinclus collinsae is currently not assessed by IUCN or other regional initiative.

Material examined. Essequibo River basin, Guyana: AMNH 55433 , holotype (measured), creek tributary to [Little] Takutu River , Cuyuni-Mazaruni, approx. 06°15’N 59°05’W. AMNH 55434 , 2 of 4 (2 measured) paratypes, same data as holotype. ANSP 175927 1, creek crossing Kurupukari-Surama River road ca. 3 miles from Kurupukari field station, Siparuni VIII-2 , PotaroSiparuni, 04°22’29”N 58°50’30”W . ANSP 175923 , 2 cs, blackwater creek 5 minutes downstream from Burro Burro campsite , Potaro-Siparuni, 04°43’58”N 58°51’18”W . ANSP 179140 , 7, MCP 34710 , 3, Whitewater Creek, small blackwater creek tributary to Mazaruni River, 6.8 km SW of Bartica, Cuyuni-Mazaruni, 06°22’41”N 58°40’25”W . AUM 28118, 7 + 2 cs, Potaro River and Amatuk cataract and beach just below cataract, Potaro-Siparuni, 05°18’14”S 59°18’40”W. AUM 28143, 2, Potaro River at Waratuk cataract, Potaro-Siparuni, 05°15’32”S 59°24’01”W . AUM 35577, 10 (8 measured) + 1 cs, Whitewater Creek, small blackwater creek tributary to Mazaruni River, 6.8 km SW of Bartica, Cuyuni-Mazaruni, 06°22’41”N 58°40’25”W . AUM 62851, 13 of 24 , MCP 54757, 10, Kuribrong River at Grass Shoals Rapids, Potaro-Siparuni, 05°28’44.7”S 59°31’54.4”W . AUM 62880, 1, Kuribrong River at Ram Sheep Rapids, PotaroSiparuni, 05°26’32.5”S 59°30’07.2”W . AUM 62896, 3, Grass Falls Creek (Kiwikparu Creek), just upstream from mouth of Kuribrong River, Potaro-Siparuni, 05°24’23.4”S 59°32’01”W. MHNG 2607.046, 2 of 3, river tributary to Essequibo River, 21.6 km from Linden on road from Linden to Rochstone, Mazaruni-Potaro, 05°59’02”N 58°31’48”W . ROM 83660, 2, Apanachi Creek, 26 mi from Issano River, along Issano-Barbica Road, Potaro-Siparuni, 05°37’14.22”W 59°13’36.46”W . ROM 101797, 2, Kurupung River, Cuyuni-Mazaruni, 06°12’40.39”N 60°09’53.35”W . ROM 102182, 3, upper Eping Creek, Cuyuni-Mazaruni, 06°06’22.75”N 60°06’24.12”W.

Figures

FIGURE 31 | Rhinotocinclus collinsae, holotype, AMNH 55433, 23.9 mm SL, female, creek tributary to Little Takutu River, Cuyuni-Mazaruni, Guyana.

FIGURE 32 | Geographical distribution of Rhinotocinclus species of the R. collinsae group in southeastern Guiana Shield. Rhinotocinclus collinsae (yellow dots); R. halbothi (red dots); R. hardmani (blue dots). T = Type-locality