Neotropical Ichthyology, 12(1):81-87, 2014 Copyright © 2014 Sociedade Brasileira de Ictiologia A new species of Microglanis (Siluriformes: Pseudopimelodidae) from the upper rio Tocantins basin, Goiás State, Central Brazil Oscar Akio Shibatta A new species of Microglanis is described from the upper rio Tocantins basin, Barro Alto, Goiás State, Brazil. This species is distinguished from the others by presenting a unique color pattern, consisting of round spots in the flank between the larger dark brown blotches. Moreover, it can be distinguished by the combination of the following features: caudal fin emarginate, the upper lobe slightly larger than the lower, lateral line relatively long, reaching vertical through posterior margin of the pelvic fin, and light stripe on supra-occipital region absent or very narrow and with irregular shape. Uma espécie nova de Microglanis é descrita da bacia do alto rio Tocantins, Barro Alto, estado de Goiás, Brasil. Essa espécie distingue-se das demais por apresentar um padrão de colorido único, constituído por manchas arredondadas no flanco entre as manchas castanho escuras maiores. Além disso, pode ser diferenciada pela combinação dos seguintes caracteres: nadadeira caudal emarginada, com o lobo superior ligeiramente maior que o inferior, linha lateral relativamente longa, atingindo a vertical que passa pela margem posterior da nadadeira pélvica, e faixa clara na região supraoccipital ausente ou muito estreita e com formato irregular. Key words: Bumble-bee catfish, Multivariate morphometrics, Neotropical, Systematics. Introduction species was discovered from the upper rio Tocantins basin, rio dos Patos, Barro Alto. With the description of this new Microglanis Eigenmann, 1912 is a group of catfishes easily species, the number of known species of Microglanis (Jarduli identified by the small size (less than 8 cm SL), incomplete & Shibatta, 2013) is increasing to 22, highlighting the Araguaia- lateral line, body with large dark brown blotches, and Tocantins basin as one of the richest in Microglanis species. premaxillary tooth plate laterally rounded (Schultz, 1944; Gomes, 1946; Mees, 1974). Material and Methods The geographic distribution is very broad in South America, occurring in coastal rivers of the trans-Andean region of Peru Morphometric variables of four specimens were taken and Ecuador, and in major watersheds of cis-Andean region point-to-point with digital caliper with accuracy of 0.01 mm, (Shibatta, 2003). Among these, the Araguaia-Tocantins basin under a stereomicroscope. Both counts and measurements was only recently recognized as area of distribution of genus, were taken on the left side of specimens whenever possible. with the description of three new species (Ruiz & Shibatta, Measurements were taken following Mori & Shibatta (2006), 2010; Ruiz & Shibatta, 2011). Particularly to the rio Tocantins with addition of head depth (measured at vertical through basin, only M. robustus Ruiz & Shibatta, 2010 was described posterior margin of eye), and body depth at dorsal fin origin, to date, but with known distribution restricted to the region of totaling 22 morphometric variables. All measurements were Tucuruí hydroelectric power plant, in Jatobal, Pará State. presented as percents of standard length (SL), and the Recently, analyzing the collection of Microglanis of subunits of head were also presented as percents of head Instituto Nacional de Pesquisas da Amazônia (INPA), a new length (HL). Meristic data included counts of gill-rakers, Departamento de Biologia Animal e Vegetal, Centro de Ciências Biológicas, Universidade Estadual de Londrina, 86051-990 Londrina, PR. [email protected] 81 82 New species of Microglanis from upper rio Tocantins serrations of pectoral-fin spine, lateral line pores, and dorsal, emarginated with upper lobe slightly longer than the lower, pectoral, pelvic, anal and caudal-fin rays. Roman numerals light spot in nuchal region very small or absent. Microglanis indicate unbranched rays and Arabic numerals represent maculatus differs from M. robustus by single hooks on branched rays. In the diagnosis and description of species, anterior margin of pectoral-fin spine (vs. bifurcated hooks the frequency of each meristic data is presented in parenthesis between antrorse and retrorse hooks), rays of pectoral fin I, 6 and the counts of the holotype are followed by asterisks. (vs. I, 5); anterior blotch of trunk U shaped (vs. inverted U Only the holotype was x-rayed to count ribs and vertebrae. shaped); broad dark stripes on dorsal and caudal fins (vs. Two additional specimens of the new species were collected thin), lower values of dorsal-fin spine length (6.9-11.1% SL with sieves, euthanized by hyper exposure of anesthetic vs. 11.3-15.4% SL), pectoral-fin spine length (12.9-17.7% SL, Eugenol (c. 3000 mg/L; Lucena et al., 2013), fixed in 10% vs. 16.4-20.6% SL), and orbital diameter (11.5-12.6% SL vs. formalin solution and preserved in 70% ethanol. Specimens 14.7-16.4% SL); and higher values of mouth width (16.8-17.5% of M. robustus, other species of rio Tocantins basin, were SL vs. 11.4-13.2% SL). used to perform the sheared Principal Components Analysis (McLeod, 1990). For this analysis, 19 variables were selected Description. Morphometric data are presented in Table 1. from original morphometric list (excluding pelvic fin length, Body depressed from snout to dorsal-fin origin; posteriorly posterior cleithral process length, and caudal peduncle length, compressed. Profile slightly oblique upward from snout tip due to limitations on number of morphometric variables to posterior nostril, slightly convex from posterior nostril to accepted by the program). Physical (temperature) and chemical nape, and convex from nape to dorsal-fin origin. Profile from (dissolved oxygen, pH, and conductivity) variables were taken dorsal-fin origin to end of adipose-fin base almost straight with multiparameter equipment, depth of water and river width (not considering adipose fin), oblique downward. Dorsal were taken with measuring tape, and the velocity of water was profile straighter on small specimens (Fig. 2). Ventral profile calculated as the time (in seconds) covered by an fluctuant from tip of lower jaw to end of anal-fin base slightly convex, object in a distance of five meters. almost straight. More convex in young specimens (Fig. 2). Institutional abbreviations are: ANSP (Academy of Natural Head large, wider than deep. Mouth terminal, slightly Sciences of Drexel University, Philadelphia); CAS (California prognathous. Opercular membrane large, well developed. Eye Academy of Sciences, San Francisco); INPA (Instituto relatively small, lateral-superiorly positioned, covered by skin. Nacional de Pesquisas da Amazônia, Manaus); MCP (Museu Anterior nostril tubular, over lip. Maxillary barbel reaching de Ciências e Tecnologia, Pontifícia Universidade Católica do distal opercular edge. Outer mental barbel reaching pectoral- Rio Grande do Sul, Porto Alegre); MEPN (Museo de la Escuela fin base. Anterior cranial fontanel not extending beyond Politécnica Nacional de Quito, Ecuador); MNHNP (Museu posterior orbital border. Nacional de Historia Natural del Paraguay, San Lorenzo); Dorsal fin trapezoidal; posterior border rounded; origin MNRJ (Museu Nacional, Rio de Janeiro); MZUEL (Museu de anterior to midpoint of standard length; not reaching adipose- Zoologia da Universidade Estadual de Londrina, Paraná); fin origin when adpressed; first lepidotrichium (“spinelet”) MZUSP (Museu de Zoologia da Universidade de São Paulo, small and rigid, forming dorsal-fin locking mechanism; second São Paulo); MHNG (Muséum d’histoire naturelle de la Ville de ray forming spine; I, 6*(4). Adipose fin slightly elongated, Genève, Geneva); USNM (National Museum of Natural posterior border angular and free. Pectoral fin triangular, not History, Smithsonian Institution,Washington, DC); and ROM reaching pelvic-fin origin when adpressed; first ray rigid and (Royal Ontario Museum, Toronto). strongly serrate on both sides (only retrorses hooks on anterior margin of pectoral fin in small specimens, and antrorses and retrorses in large specimen (Fig. 3), all single; I, Microglanis maculatus, new species 6*(4). Pelvic fin rounded, originating just posterior to vertical Figs. 1-3 through end of dorsal-fin base, not reaching anal-fin origin when adpressed; i, 5*(4). Distal profile of anal fin rounded; Holotype. INPA 41133, 36.5 mm SL, Brazil, Goiás, município de anal-fin base length slightly smaller than adipose-fin base; Barro Alto, upper rio Tocantins basin, ribeirão Pouso Alegre, tributary iii, 7*(2) or iv, 5(2). Caudal fin emarginated, lobes distal profile of rio dos Patos, 15°01’26"S 48°49’51"W, 12 Jul 2010, O. A. rounded, upper lobe slightly longer than lower lobe; principal Shibatta, A. Claro-García, L. R. Jarduli & E. Santana da Silva. rays 7, 8*(4). Paratypes. INPA 24044, 2, 21.4-25.8 mm SL, Brazil, Goiás, Pores of lateral-line extending just beyond vertical município de Barro Alto, Igarapé Veredas, rio dos Patos basin, 17 through posterior margin of pelvic-fin. Total gill rakers 7(1), Jun 2004, G. M. dos Santos. MZUEL 5925, 1, 20.5 mm SL, same 8(1), or 9*(2). Axillary pore absent. Six ribs; free vertebral data as holotype. centra 26 (total = 32 vertebrae) in holotype. Diagnosis. Microglanis maculatus differs from all its Color in alcohol. Dorsal region of head, from tip of snout to congeners by the presence of rounded spots in the flank. nape, dark brown, ventrally continuing in suborbital and Furthermore, it differs from its congeners, except M. robustus, opercular region to horizontal passing through angle of by the following combination of features: caudal fin mouth; intermediate region with light blotch. Ventral region O. A. Shibatta 83 Fig. 1. Microglanis maculatus, holotype, INPA 41133, 36.5 mm SL, ribeirão Pouso Alegre, tributary of rio dos Patos, upper rio Tocantins basin, Barro Alto, Goiás State, Brazil. 84 New species of Microglanis from upper rio Tocantins Fig. 2. Microglanis maculatus, paratype, MZUEL 5925, 20.5 mm SL, ribeirão Pouso Alegre, tributary of rio dos Patos, upper rio Tocantins basin, Barro Alto, Goiás State, Brazil. of head light with dark spots.