Rhinotocinclus halbothi ( Lehmann, Lazzarotto & Reis, 2014 ), 2022

Rhinotocinclus halbothi ( Lehmann, Lazzarotto & Reis, 2014) , new combination

( Fig. 33 View FIGURE 33 ; Tab. 6 View TABLE 6 )

Parotocinclus halbothi Lehmann, Lazzarotto & Reis, 2014:28 (Type-locality: Brazil, Pará, Oriximiná, creek tributary to igarapé do Moura at Platô Monte Branco, rio Trombetas drainage, Amazon basin, 01°35’58.09”S 56°31’21.83”W. Holotype: MCP 48029).

Diagnosis. Rhinotocinclus halbothi is distinguished from all congeners, except R. collinsae and R. hardmanni , 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 halbothi 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. pentakelis , R. loxochelis n. sp., and R. marginalis n. sp. by possessing an adipose fin ( vs. adipose fin absent). Rhinotocinclus halbothi is distinguished from R. collinsae and R. hardmanni by having 4–7 series of middle abdominal plates ( vs. 0–1 series). It is further distinguished from R. collinsae by having the adipose-fin spine coalesced to the dorsum ( vs. adipose fin normally developed), and by a shorter pectoral fin (46.3–55.8% vs. 58.2–69.1% HL); and from R. hardmanii by having many and large accessory teeth ( vs. few and minute teeth), a normally developed urogenital papilla in males (Fig. 2B; vs. urogenital papilla 3–4 times bigger than normal, Fig. 2C), 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 halbothi occurs in the rio Trombetas basin, a tributary to the Amazon in the states of Amazonas and Pará, Brazil, and in the upper Marowijne River, in southern Suriname ( Fig. 32 View FIGURE 32 ).

Remarks. Rhinotocinclus halbothi , listed as Parotocinclus halbothi , is currently assessed as Least Concern (LC) in the Brazilian regional assessment by ICMBio (2018).

Material examined. Brazil: MCP 48029 , holotype (measured), MCP 48030 , 6 paratypes (6 measured), MCP 48098 , 1 cs paratype (measured), INPA 39890 , 4 + 1 immature paratypes (4 measured), creek tributary to igarapé do Moura at Platô Monte Branco , rio Trombetas drainage, Oriximiná, Pará, 01°35’58.09”S 56°31’21.83”W. GoogleMaps MPEG 17299 , 2 paratypes, igarapé 1500 on track 4, Estação Ecológica Grão-Pará, upper rio Mapuera , rio Trombetas basin, Pará, 01º16’20.8”N 58º41’09.2”W. GoogleMaps Suriname: USNM 408454 , 1 paratype, left tributary to upper Paloemeu River , 1 km downstream of basecamp, Marowijne River basin, Sipaliwini, 02º28’38”N 55º38’17”W. GoogleMaps USNM 409918 , 2 paratypes, downstream waterfall in right tributary of upper Paloemeu River , Marowijne River basin, Sipaliwini, 02º27’21”N 55º37’35”W. GoogleMaps