Rhinotocinclus chromodontus ( Britski & Garavello, 2007 ), 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 : 80-81

Rhinotocinclus chromodontus ( Britski & Garavello, 2007) , new combination

( Fig. 42 ; Tab. 9 )

Hisonotus chromodontus Bristski & Garavello, 2007:414 (Type-locality: Brazil: Mato Grosso State: Diamantino, creek number 1, tributary of Rio Preto, on road to São Francisco, Rio Arinos drainage, ca. 14°18’S 56°20’W. Holotype: MZUSP 45355).

Diagnosis. Rhinotocinclus chromodontus is distinguished from congeners, except R. acuen , R. jumaorum , 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. hera , R. jumaorum , and R. dinizae , by lacking an adipose fin or platelets at the adipose-fin position (vs. adipose fin or platelets present). Rhinotocinclus chromodontus is distinguished from R. acuen , R. jumaorum , and R. dinizae by having the caudal fin mostly brown, with two hyaline spots on upper and lower lobes ( Fig. 42 ; vs. caudal fin with a dark blotch at base and two irregular dark bands), and from R. acuen , R. dinizae , R. hera by having the oral teeth reddish brown (vs. teeth light ochre). It is further distinguished from R. acuen , R. dinizae , R. hera , and R. jumaorum by the dorsal- and pectoral-fin spines homogeneously dusky (vs. spines with 2–3 dark dots).

Geographical distribution. Rhinotocinclus chromodontus occurs in the upper rio Tapajós basin, in the state of Mato Grosso ( Fig. 43 ).

Remarks. Two species of Hisonotus were described by Britski, Garavello (2007), H. chromodontus and H. luteofrenatus , from the upper rio Tapajós, being thus compared to other Hisonotus species. Hisonotus luteofrenatus has already been transferred to Curculionichthys and H. chromodontus is herein being transferred to Rhinotocinclus . We take this opportunity to mention that figures 3a and b are interchanged in Britski, Garavello (2007), as can be easily noticed by the single rostral plate of Rhinotocinclus (compared to the paired rostral plate of Curculionichthys ) and the posteriorly projected canal cheek plate (compared to the mesially projected plate of Curculionichthys ). Rhinotocinclus chromodontus , listed as Hisonotus chromodontus , is currently assessed as Least Concern (LC) in the Brazilian regional assessment by ICMBio (2018).

Material examined. Brazil, Mato Grosso State, Rio Tapajós basin: MZUSP 45255 , holotype (measured), riacho Três, tributary to rio Preto on road to São Francisco , Diamantino, approx. 14°16’S 56°19’W . MCP 37636 , 5 paratypes (4 measured), rio Sumidouro Grande, tributary to rio Arinos on farm Arrossensal , Nortelândia, approx. 14°05’S 56°45’W . AUM 73895 , 10, INPA 59666, 10, MCP 35873, 150+ 10 cs, MHNG 2787.079, 10, ROM 111487, 10, rio Sauê-Uiná below dam on road BR-364 towards Sapezal, Sapezal, 13°32’22”S 58°50’48”W. MCP 32648, 3, creek on road MT-338, ca. 158 km N of Tapurah, Simione, 11°42’13”S 56°56’17”W. MCP 32649, 28, creek on road MT-338, ca. 33 km N of Tapurah, Tapurah, 12°29’46”S 56°40’43”W . MCP 32650, 9, creek ca. 20 km NW of São José do Rio Claro, on road to Nova Maringá, São José do Rio Claro, 13°20’29”S 56°51’07”W. MCP 32651, 6 (3 measured), creek on road MT-010, from Diamantino to São José do Rio Claro, 96 km NW of Diamantino, São José do Rio Claro, 13°37’05”S 56°34’27”W . MCP 32652, 6, ribeirão Macuco on road BR-163, ca. 74 km N of Sinop, Sinop, 11°17’35”S 55°19’10”W. MCP 32653, 1, rio Roquete on road BR-163 ca. 45 km N of Sinop, Sinop, 11°32’20”S 55°23’35”W . MCP 32654, 16, creek on road MT-338, ca. 89 km N of Tapurah, Tapurah, 12°01’49”S 56°33’59”W . MCP 32655, 2, creek on road from road MT-010 to Nova Mutum, ca. 11 km W from ferry crossing rio Arinos, São José do Rio Claro, 13°37’23”S 56°29’18”W . MCP 32656, 2, creek ca. 22 km NW of São José do Rio Claro, on road to Nova Maringá, São José do Rio Claro, 13°19’24”S 56°51’22”W. MCP 32657, 1, creek on road MT-338, ca. 46 km N of Tapurah, Tapurah, 12°23’14”S 56°41’54”W . MCP 32658, 1, creek on road MT-338, ca. 131 km N of Tapurah, Simione, 11°47’40”S 56°44’09”W . MCP 32659, 4, creek on farm Esplanada Arinos, on road from road MT-010 and ferry to Nova Mutum, São José do Rio Claro, 13°36’31”S 56°32’10”W . MCP 32660, 134 (3 measured), igarapé Ribeirão Preto, on road MT-338, ca. 26 km ESE of Porto dos Gaúchos, Porto dos Gaúchos, 11°39’27”S 57°12’07”W . MCP 32674, 1, creek tributary to rio Caibi on road MT-140 from Santa Carmen to Vera, Vera, 12°10’40”S 55°20’23”W . MCP 32675, 62 + 5 cs, rio Celeste ca. 9 km W of Nova Ubiratã, on road to Sorriso, Nova Ubiratã, 13°03’08”S 55°21’13”W . MCP 32677, 5 + 1 cs, creek tributary to rio Celeste ca. 47 km NW of Nova Ubiratã on road to Sorriso, Sorriso, 12°45’47”S 55°31’05”W . MCP 32678, 19 + 2 cs, córrego Maria (or Quinze), on road BR-163 ca. 23 km N of Sinop, Sinop, 11°43’16”S 55°27’33”W . MCP 35871, 1, córrego Água Quente, on road from Sapezal to rio Papagaio, Sapezal, 13°32’25”S 58°43’32”W. MCP 44413, 16, creek on road MT-235 from Nova Mutum to Santa Rita do Trivelato, Nova Mutum, 13°48’55”S 56°02’39”W. MCP 44419, 2, córrego Conguinha on road MT-235, from Nova Mutum to Santa Rita do Trivelato, Nova Mutum, 13°47’44”S 55°53’25”W . MCP 44447, 10, rio Criquiri, ca. 8 km from Nova Mutum, Nova Mutum, 13°48’11”S 56°09’23”W . MCP 44473, 2, rio dos Patos on road MT-235 from Nova Mutum to Santa Rita do Trivelato, Nova Mutum, 13°48’00”S 56°01’36”W. MZUEL 7882, 18, córrego Água Quente, tributary to rio Papagaio, rio Juruena basin, Sapezal, 13°32’25.5”S 58°43’34.8”W . MZUEL 9067, 7, córrego Santa Cruz, tributary to rio Papagaio, rio Juruena basin, Brasnorte, 12°48’21.7”S 58°09’21.5”W. MZUEL 9068, 10, rio do Calor, tributary to rio Papagaio, rio Juruena basin, Sapezal, 13°02’57.1”S 58°39’15.7”W . MZUEL 9070, 3, tributary to rio Norato (or Honorato), itself a tributary to rio do Sangue, rio Juruena basin, ca. 7 km S of Brasnorte, 12°11’12.9”S 57°59’33.3”W . MZUEL 9073, 3, tributary to rio Juruena at km 363 of road MT-170, Juína, 11°31’35.0”S 58°24’29.3”W. MZUSP 61115, 5, rio Criquiri, tributary to rio dos Patos, Nova Mutum, approx. 13°51’S 56°11’W.

Figures

FIGURE 42 | Rhinotocinclus chromodontus, MCP 32660, 25.2 mm SL, male, igarapé Ribeirão Preto, on road MT-338, ca. 26 km ESE of Porto dos Gaúchos, Porto dos Gaúchos, Mato Grosso, Brazil.

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.