Inpaichthys nambiquara (Bertaco & Malabarba, 2007) Ferreira & Ribeiro & Lima & Silva & Ferreira & Mirande, 2024

Ferreira, Katiane M., Ribeiro, Alexandre C., Lima, Flávio C. T., Silva, Hugmar P. da, Ferreira, Daniela C. & Mirande, Juan Marcos, 2024, A new species of Inpaichthys from the rio Canamã, rio Aripuanã basin, Mato Grosso State, Brazil, with a redefinition of the genus (Characidae: Stethaprioninae), Neotropical Ichthyology (e 230113) 22 (1) : -

Inpaichthys nambiquara (Bertaco & Malabarba, 2007) , new combination

( Fig. 1)

Hasemania nambiquara Bertaco & Malabarba, 2007:350–53 (Type-locality: “ Brazil, Mato Grosso, Comodoro, rio Doze de Outubro on Highway BR-364 between Comodoro and Vilhena, tributary of rio Juruena, upper rio Tapajós drainage, 12º58’39”S 60º00’30”W ”; see Remarks below). ―Ohara, Loeb, 2016:3–6 ( Brazil, Mato Grosso State, igarapé Mutum, rio Juruena basin; photo in life, abundance) .

Diagnosis. Five morphological autapomorphies were found for Inpaichthys nambiquara : third infraorbital not reaching horizontal arm of preopercle in its anterior margin (88:1), presence of (a reduced, in this species) fourth infraorbital (90:0), three or fewer maxillary teeth (190:0), five or more cusps on anterior maxillary teeth (193:1), and the possession of four or fewer supraneurals (392:0). Inpaichthys nambiquara can be easily distinguished from both I. kerri and the new taxon herein described by the absence of an adipose fin (vs. adipose fin present in other Inpaichthys species), and by having a conspicuous dark stripe along predorsal area (vs. absence of a conspicuous dark stripe along predorsal area in the remaining Inpaichthys species). Inpaichthys nambiquara can additionally be distinguished from the new species by the following combination of characters: presence of a conspicuous, broad, ventrally curved midlateral stripe extending from snout to caudal peduncle (vs. presence of a narrow, straight dark midlateral stripe along the longitudinal septum of body, extending from second humeral blotch to median caudal-fin rays), absence of six red dotted longitudinal stripes on the body flanks in living specimens (vs. presence), 16–18 branched anal-fin rays (vs. 21–25 branched anal-fin rays), presence of a single humeral blotch (vs. two humeral blotches), and largest dentary teeth with five cusps (vs. largest dentary teeth with three cusps). Inpaichthys nambiquara can additionally be distinguished from I. kerri by the presence of a humeral blotch (vs. absence of any humeral blotch), and 2–3 maxillary teeth, largest one pentacuspid (vs. 6–9 maxillary teeth, largest tricuspid), respectively.

Description. See Bertaco, Malabarba (2007) for a complete description of the species.

Remarks. The type-locality of Inpaichthys nambiquara was originally indicated to be at the rio Doze de Outubro at the road BR-364. The rio Doze de Outubro is a tributary of the rio Camararé, a major tributary of the rio Juruena. Ohara, Loeb (2016) sampled extensively some of the headwater tributaries of the rio Camararé crossing the highlands of the Chapada dos Parecis at the road BR-364, including the rio Doze de Outubro, and only collected the species at the rio Mutum, another tributary of the rio Camararé, which runs parallel to the rio Doze de Outubro, roughly 20 km apart along their lengths (> 100 km) before joining the rio Camararé. Despite their proximity and the fact that they both belong to the same sub-basin, they are apparently quite distinct in the composition of their ichthyofaunas (Ohara, Loeb, 2016). The type-locality of I. nambiquara has been recently recognized as being incorrectly stated in the original description, and to be indeed the rio Mutum ( V. A. Bertaco, 2023, pers. comm.). In fact, one of the authors ( FCTL) participated in the field expedition where the typematerial of I. nambiquara was obtained and photographed specimens sampled at the rio Mutum, including a specimen of I. nambiquara , which lends support to the idea that the locality was incorrectly stated at the original description. We take this opportunity to amend the type-locality of the species to “ Brazil, Mato Grosso, Comodoro, rio Mutum, tributary of rio Camararé, at highway BR-364 between Comodoro and Vilhena, rio Juruena basin, 13º05’08”S 59º53’32”W ”. In the original description, Bertaco, Malabarba (2007) did not mention the presence of sexual dimorphism in the species. However, H.-G. Evers (2023, pers. comm.), who bred the species in captivity, noticed that males are slightly larger than females, presenting a dark margin on the anal fin, and present a broader midlateral stripe (compare Figs. 1A–B). Inpaichthys kerri apparently possesses a similar sexual dimorphism, with males presenting a broader midlateral stripe and an anal-fin margin straighter than females (see Pastana et al., 2017:1308, figs. 3E–F).

Material examined. Inpaichthys nambiquara . Brazil, Mato Grosso State, Comodoro, upper rio Tapajós basin: MCP 38038 , paratypes, 2 of 4, 1 c&s, 21.1–23.5 mm SL .