A new genus of armored catfish (Siluriformes: Loricariidae) from the Greater Amazon, with a review of the species and description of five new species Author Reis, Roberto E. PontifÍcia Universidade Católica do Rio Grande do Sul. Av. Ipiranga, 6681, P. O. Box 1429, 90619 - 900 Porto Alegre, RS, Brazil. reis@pucrs.br Author Lehmann A., Pablo Laboratório de Ictiologia, Universidade do Vale do Rio dos Sinos. Av. Unisinos, 950, 93022 - 000 São Leopoldo, RS, Brazil. pablole@unisinos.br. text Neotropical Ichthyology 2022 e 220002 2022-07-08 20 2 1 100 http://dx.doi.org/10.1590/1982-0224-2022-0002 journal article 10.1590/1982-0224-2022-0002 1f6c7a0d-e5f8-479d-be08-03fd894b7cfe 1982-0224 13350428 0A755C8D-B807-41CF-825B-BD3209119D54 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). 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 . 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 .