Rhinotocinclus hardmani (Lehmann, Lujan & Reis, 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 : 61-63

Rhinotocinclus hardmani (Lehmann, Lujan & Reis, 2022) , new combination

( Fig. 34 ; Tab. 6 )

Parotocinclus hardmani Lehmann, Lujan & Reis, 2022:2 (Type-locality: Kuribrong River at Grass Shoals Rapids, Potaro-Siparuni, Guyana, 05°28’44.7”N 59°31’54.4”W. Holotype: CSBD F3618).

Diagnosis. Rhinotocinclus hardmanni is distinguished from all congeners, except R. collinsae and R. halbolthi , by having accessory teeth on both premaxilla and dentary (Fig. 5A; accessory teeth absent, Figs. 5B,C); the odontodes on the ventral surface of first pelvic-fin 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 (vs. light mark present and Y-, V-shaped or as two separate lines). Rhinotocinclus hardmanni 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 hardmanni is distinguished from R. collinsae and R. halbothi by having few and minute teeth accessory teeth (vs. many and large), a large urogenital papilla in males, 3–4 times bigger than normal (Fig. 2C; vs. normally developed urogenital papilla, Fig. 2B), by lacking a skin flap on first pelvic-fin ray of males (vs. skin flap present), and having the belly naked or almost naked between lateral abdominal plates (vs. fully plated belly). It is further distinguished from R. collinsae by having the adipose-fin spine coalesced to the dorsum (Fig. 4C; vs. adipose fin normally developed, Figs. 4A,B), and from R. halbothi by having fewer premaxillary teeth (18–22 vs. 28–32 teeth).

Geographical distribution. Rhinotocinclus hardmani occurs in the Potaro River, Essequibo River basin in the Region of Potaro-Siparuni, Guyana ( Fig. 32 ).

Remarks. Rhinotocinclus hardmani is sympatric and syntopic with R. collinsae in the Potaro River, having been collected together at the same spot. Despite both species are superficially similar, they have many distinguishing characters. Rhinotocinclus hardmani is easily diagnosed from R. collinsae by having few and minute teeth accessory teeth, while they are numerous and large in R. collinsae , by the large urogenital papilla of males, which is 3–4 times bigger than that of R. collinsae , by males lacking a skin flap on first pelvic-fin ray, which is present in R. collinsae , by having the belly naked or almost naked between lateral abdominal plates, while it is fully plated in R. collinsae , and by having the adipose-fin spine coalesced to the dorsum, while it is free from the dorsum on R. collinsae . Rhinotocinclus hardmani was tentatively categorized as Least Concern (LC) by Lehmann et al. (2022) in the original description.

Material examined. Essequibo River basin, Guyana: CSBD F3618 , holotype (measured), AUM 62850 , 78 paratypes (9 measured), CSBD F3619 , 10 paratypes , MCP 54588 , 17 (9 measured) + 3 cs paratypes , ROM 110801 , 10 paratypes, UMMZ 252792 , 10 paratypes, Kuribrong River at Grass Shoals Rapids , Potaro-Siparuni, 05°28’44.7”N 59°31’54.4”W. AUM 62879 , 17 of 33 paratypes, Kuribrong River at Ram Sheep Rapids , Potaro-Siparuni, 05°26’32.5”S 59°30’07.2”W. AUM 62895 , 14 of 26 paratypes, Grass Falls Creek (Kiwikparu Creek), just upstream from mouth of Kuribrong River , Potaro-Siparuni, 05°24’23.4”S 59°32’01”W. INHS 49522 , 5 + 1 cs paratypes, Potaro River at Amatuk Cataract , Potaro-Siparuni, 05°18’13.5”N 59°18’40.2”W. INHS 49555 , 2 paratypes, 19.1–22.8 mm SL + 1 cs, INHS 49556 , 1, 23.5 mm SL, Potaro River at Waratuk Cataract , Potaro-Siparuni, Guyana, 05°15’31.9”N 59°24’ 01.0”W. ROM 91423 , 17 paratypes, Mikobe Creek , approx. 0.5 km upstream from mouth, at rapids beyond first rapid blocking upstream boat entry, Potaro-Siparuni, 05°24’50.25”N 59°28’12.91”W . ROM 111040 , 49 paratypes, creek entering Kuribrong River at upper Grass Falls, at lowermost series of rapids near mouth , Potaro-Siparuni, 05°24’26.55”N 59°31’57.05”W.

Figures

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

FIGURE 34 | Rhinotocinclus hardmani, holotype, CSBD F3618, 22.7 mm SL, female, Kuribrong River at Grass Shoals Rapids, Potaro-Siparuni, Guyana.