Rhinotocinclus jumaorum (Dias, Silva, Oliveira & Roxo, 2018), 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 : 87-88

Rhinotocinclus jumaorum (Dias, Silva, Oliveira & Roxo, 2018) , new combination

( Fig. 45 ; Tab. 9 )

Hisonotus jumaorum Dias, Silva, Oliveira & Roxo, 2018:578 (Type-locality: Brazil, Amazonas state, municipality of Apuí, rio Juma, tributary of rio Aripuanã, rio Madeira basin, 07°12’43.7”S 59°55’19.6”W. Holotype: MZUSP 123835).

Diagnosis. Rhinotocinclus jumaorum is distinguished from congeners, except R. acuen , R. chromodontus , and R. dinizae , by having the dominant color pattern formed by a dark stripe from the snout tip, through the eye and extending to end of caudal peduncle (Fig. 7E; vs. dominant color pattern formed by dark bars separated and distinct, or dark bars wide and partially coalesced or closed together), and by having a V-shaped light mark from the snout tip to each nostril (Figs. 6C,D; vs. light mark absent, Y-shaped or present as two separate lines from snout tip diverging to each nostril). It is also distinguished from congeners, except R. acuen , R. chromodontus , R. dinizae , and R. hera , by lacking an adipose fin or platelets at the adipose-fin position (vs. adipose fin or platelets present). Rhinotocinclus jumaorum is distinguished from R. acuen by having oral teeth brown (vs. light ochre), and by the relative proportion of caudal peduncle depth and body width (caudal peduncle depth 35.4–39.0% vs. 39.2–45.0% cleithral width). It is distinguished from R. chromodontus by having the caudal fin with a dark blotch at the base and two irregular dark bands (vs. caudal fin mostly brown, with two hyaline spot on upper and lower lobes), the dorsal- and pectoral-fin spines with 2–3 dark dots (vs. spines homogeneously dusky), a shorter pectoral-fin spine (23.3–26.7% vs. 26.7–29.5% SL and 60.8–68.9% vs. 71.4–78.4% HL), and narrower body (cleithral width 22.4–24.9% vs. 24.9–27.9% SL and 59.4–67.2% vs. 67.7–76.2% HL). Rhinotocinclus jumaorum is distinguished from R. dinizae by having teeth with brown cusps (vs. cusps light ochre); a shorter pectoral-fin spine (23.3–26.7% vs. 28.1–30.0% SL); a shorter head (36.4–39.7% vs. 40.0–41.8% SL); and more numerous teeth (20–33 premaxillary vs. 16–19, and 18–28 dentary vs. 12–15).

Geographical distribution. Rhinotocinclus jumaorum occurs in the rio Juma, a small tributary to the rio Aripuanã and the rio Acari, a tributary to the rio Canumã, rio Madeira basin, in state of Amazonas, Brazil ( Fig. 43 ).

Remarks. Rhinotocinclus jumaorum was also described as a member of Hisonotus by Dias et al. (2018), disregarding the study of Calegari et al. (2017) which redefined Hisonotus and restricted its distribution to the La Plata basin and coastal rivers from Uruguay to Espirito Santo State, Brazil. For this reason, and based on the fact that Hisonotus jumaorum shares some diagnostic features of Curculionichthys and is distributed in Amazon tributaries running on the Brazilian Shield, Calegari et al. (2018) reallocated the species as Curculionichthys jumaorum . Roxo et al. (2019), however, transfered the species back to Hisonotus . Extintion risk of Rhinotocinclus jumaorum is currently not assessed.

Material examined. Rio Madeira basin, Apuí, Amazonas State, Brazil: MZUSP 123835, holotype (measured), rio Juma, tributary to rio Aripuanã on Transamazon road (BR-230) between vila do 180 and Apuí, 07°12’43”S 59°55’18”W. MZUSP 122325, 26 (4 measured), rio dos Pombos on vicinal road dos Pombos, rio Juma basin, 07°10’59.45”S 60°01’50.88”W. MZUSP 122389, 9, MCP 54758, 8 (3 measured) + 2 cs, rio Juma on vicinal road ca. 6 km from Transamazon road (BR-230), 07°16’45”S 59°57’03”W. MZUSP 122482, 12 (3 measured), creek 2, on vicinal road Dom Pedro, rio Acari basin, 06°50’22.34”S 59°42’26.89”W. MZUSP 122505, 1 (measured), creek 1, tributary to rio Coruja on vicinal road Coruja, rio Juma basin, 07°16’39.61”S 59°51’28.76”W. MZUSP 122639, 1 (measured), igarapé Andorinha, tributary to rio Acari on vicinal road Três Estados, 07°06’31.87”S 59°35’52.62”W. MZUSP 122687, 1 (measured), creek on South branch of Transamazon road (BR-230), 35 km S of Apuí, rio Acari basin, 07°26’21.59”S 59°50’53.81”W. MZUSP 122369, 1, igarapé do Mutum on vicinal road Brasília at Fazenda Nova Esperança, ca. 5 km from Transamazon road (BR-230), 07°14’57”S 59°58’41”W. MZUSP 122975, 4, rio Juma on Transamazon road (BR-230), 07°12’43.49”S 59°55’18.78”W.

Figures

FIGURE 43 | Geographic distribution of Rhinotocinclus species of the R. chromodontus group in southern Amazon. Rhinotocinclus acuen (red dots); R. chromodontus (blue dots); R. dinizae (cyan dots); R. jumaorum (yellow dots). T = Type-locality.

FIGURE 45 | Rhinotocinclus jumaorum, MCP 54758, 27.0 mm SL, male, rio Juma on vicinal road ca. 6 km from Transamazon road (BR-230), Apuí, Amazonas, Brazil.