Siluriformes: Pimelodidae), a New Species of Catfish from Affluent Rivers of Laguna Merín, Uruguay, South America
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ISSN 0097-3157 PROCEEDINGS OF THE ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA 157: 149-162 JULY 2008 Pimelodus pintado (Siluriformes: Pimelodidae), a new species of catfish from affluent rivers of Laguna Merín, Uruguay, South America MARÍA DE LAS MERCEDES AZPELICUETA Division Zoología Vertebrados, Museo de La Plata, Paseo del Bosque, 1900 La Plata, ARGENTINA, Email: [email protected] JOHN G. LUNDBERG Department of Ichthyology, Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103 USA, Email: [email protected] MARCELO LOUREIRO Zoología Vertebrados, Facultad de Ciencias, Iguá 4438, Montevideo, URUGUAY, Email: [email protected] ABSTRACT.—We describe a new species of pimelodid catfish belonging to the genus Pimelodus from the Cebollatí, Tacuarí and Yaguarón rivers emptying into the Laguna Merín, Uruguay. Pimelodus pintado n. sp. is distinguished from congeners by the combination of its densely spotted pigmentation pattern with many small dots irregularly placed over flanks, head and all fins, and, when fresh, metallic golden background color, plus thick striated lips with prominent rictal folds, long snout, prominent upper jaw, anterior naris far from snout margin, narrow premaxillary tooth bands with rounded posterolateral corners, tooth- less prevomer and 22-26 gill rakers on first branchial arch. Pimelodus pintado is compared to other spotted species of Pimelodus including P. maculatus, P. heraldoi, P. absconditus, P. microstoma, P. mysteriosus, P. paranaensis, P. platicirris, P. ortmanni, P. britskii, P. fur, P. grosskopfii, P. navarroi, P. coprophagus and P. punctatus. New taxon: Pimelodus pintado Azpelicueta, Lundberg and Loureiro INTRODUCTION Merín (Fig. 1). The first specimens of the new species were detected in 1997 by one of us (MMA) in the collection The type species of the taxonomically challenging of the Museu de Ciências e Tecnologia, Porto Alegre, and genus Pimelodus is P. maculatus LaCepède 1803, a boldly later at the Academy of Natural Sciences, Philadelphia and spotted catfish described from the lower Paraná River and in a loan of Uruguayan Pimelodus from the Naturhistoriska ranging widely throughout that basin (Ringuelet et al., Riksmuseet, Stockholm. Subsequent collecting in Uruguay 1967). Populations of Pimelodus with spotted pigment- conducted by MMA and ML yielded several additional ation from other Atlantic slope rivers including the São specimens reported herein. Francisco River (Britski et al., 1984) are often identified The Merín and dos Patos lagoons constitute the most as P. maculatus. Some of these are, however, sufficient- important (>6,000 km2) coastal, fresh to brackish water ly divergent to be recognized as distinct species. In fact, system in southern South America. The lagoons are situated several other weakly to strongly maculated but otherwise along the coasts of Uruguay and southeastern Brazil where distinct species of Pimelodus occur in the Paraná or São they receive many streams and rivers and the dos Patos Francisco rivers including some recently described: opens to the Atlantic Ocean. The freshwater catfishes of P. absconditus Azpelicueta, 1995, P. britskii Gravello the area include species of the families Callichthyidae, and Shibatta, 2007, P. fur (Lütken 1874), P. heraldoi Heptapteridae, Loricariidae, Trichomycteridae and Azpelicueta, 2001, P. microstoma Steindachner, 1877 (see Pimelodidae (Malabarba, 1989, Garcia and Vieira, 2001). Ribeiro and Lucena, 2007), P. mysteriosus Azpelicueta, The species described herein adds an endemic species to 1998, P. ortmanni Haseman, 1911, P. paranaensis Britski the regional fauna. and Langeani, 1988, P. platicirris Borodin, 1927, and P. pohli Ribeiro and Lucena, 2006. MATERIALS AND METHODS In this paper we describe a new and strikingly- spotted species of Pimelodus from the Cebollatí, Tacuarí Seventeen specimens of the new species were obtained and Yaguarón rivers in Uruguay that empty into Laguna from museum collections and collaborative fieldwork 150 M.M. AZPELICUETA, J.G. LUNDBERG AND M. LOUREIRO in Paso de Averías , close to bridge of Ruta 14, 33°36’49’’ S, 54°19’50’’ W, Feb. 24 2007, coll. M. Azpelicueta, M. Loureiro, S. Clavijo (Fig. 1). Paratypes.—All from Uruguay. AI 225, 188.6 mm SL, from the type locality, Feb. 25, 2007. AI 224, 188.0 mm SL, Departamento Cerro Largo, Merín- Patos system, río Yaguarón in río Branco, 32°35’S, 53°21’W, Oct. 30, 2006, coll. P. Laurino, J. Litz, M. Litz, T. Litz, J. Salvia. MNHN 3217, 157 mm SL, collecting data as AI 224. ANSP 187381, 3 specimens including one dry skeleton, 172.0-238.8 mm SL, from the type locality, Feb. 25, 2007. ZVC-P 6483, 5 speci- mens, 191.0-280.5 mm SL, from the type locality, Feb. 25, 2007. ZVC-P 6484, 149.0 mm SL, Departamento Treinta y Tres, río Tacuarí in Paso del Dragón (Ruta 18), 32°46’18’’ S, 53°44’57’’ W, Feb. 23, 2001, coll. M. Loureiro. NRM 48001, 4 specimens, 108.3-176 mm SL, Departamento Cerro Largo, Merín-Patos system, río Yaguarón in Paso del Centurión, 32°06’S, 53°45’W, No Date, coll. F. Cantera. ANSP 54060, 239 mm SL, Departamento Cerro Largo, 1932, coll. F. Felippone. Non-type specimen.—AI 235, 1 dry skeleton, Uruguay, río Cebollatí in Paso de Averías. Diagnosis.—A species of Pimelodus distin- Fig. 1. Geograpahical distribution of Pimelodus pintado n. sp., star indicates the type locality. 1, río Yaguaron, 2, río Tacuarí, 3, guished from congeners by the following combina- río Cebollatí, 4, Laguna Merín. tion of features. Larger specimens (>200 mm SL, Figs. 2, 3A) with numerous, irregularly scattered carried out in Uruguay beginning in 2001. The majority black spots on dorsum and sides of body and head, of specimens in the type series are alcohol preserved; two usually also on dorsal, adipose and caudal fins, and partial skeletons were prepared by manual removal of soft often pectoral, pelvic and anal fins; smaller specimens tissues. have larger spots arranged about in 4 rows (Fig. 3B); Measurements are straight-line distances taken fresh background color golden yellow (Fig. 3A); lips with caliper to nearest 0.1 mm. Measurements follow thick, plicate with prominent rictal folds (Fig. 2C); Azpelicueta (2001) as defined in Lundberg et al. (1991). upper jaw and snout projecting beyond mandibular Proportions are expressed as percentages of standard symphysis, exposing premaxillary teeth; anterior length (SL), head length (HL), or otherwise as indicated. nares relatively remote from snout margin; prevomer Counts were made of total fin rays in all fins; vertebral toothless; 22-26 gill rakers on first branchial arch. counts include all five elements of the Weberian complex; Description.—Morphometric data for the holo- the compound preural+ural centra is counted as one. type and 14 paratypes are presented in Table 1. Institutional acronyms are as listed on the Catalog Pimelodus pintado n. sp. (Figs. 2, 3) is a medium sized of Fishes website at http://www.calacademy.org/research/ pimelodid with a maximum known length of 280.5 ichthyology/catalog/abtabr.html. mm SL. Dorsal profile of body nearly straight from snout tip to base of supraoccipital posterior process, Pimelodus pintado, new species then slightly to strongly convex to dorsal-fin origin, Figs. 2, 3 straight or slightly convex from dorsal-fin origin to adipose-fin origin (larger specimens) or end (smaller Holotype.—ZVC P 6482, 241 mm SL, Uruguay, specimens), straight or slightly concave across caudal Departamento Rocha, Merín-Patos System, río Cebollatí peduncle. Ventral profile slanting convexly ventrally NEW PIMELODUS FROM LAGUNA MERÍN BASIN, URUGUAY 151 Fig. 2. Pimelodus pintado n. sp. A. Holotype in lateral view, ZVC P 6482, 241 mm SL, B. Paratype, dorsal view of head, ANSP 54060, 239 mm SL, C. Paratype, ventral view of head, NRM 48001, 176 mm SL. from snout tip to pectoral-fin origin, generally straight or 80% of distance between both naris (Fig. 2A). Distance convex across abdomen to anal-fin origin, then slanting between anterior and posterior nostrils less than distance dorsally to slightly concave caudal peduncle. between the latter and anterior orbital margin. Long Cross-sectional shape roughly trapezoidal from snout axis of the posterior nostril oblique to longitudinal body to base of supraoccipital posterior process, then deeply and axis; posterior nostril preceded by a large, semicircular broadly triangular to dorsal-fin origin, and increasingly membrane. compressed to caudal fin. Maximum body depth at dorsal- Eye large, placed dorsolaterally and centered a little fin origin, contained 3.8-4.9 times in SL. Maximum body behind midpoint of bony head length; interorbital space width across cleithra in front of pectoral spine insertions, scarcely concave or flat. Depth of head between eyes 1.8- contained 4.5-5.6 times in SL. 2.2 times into HL; width of head at eye 1.3-1.8 times into Head of moderate length, contained 3.3-3.6 times in HL. Interorbital wide, containing horizontal eye diameter SL, and relatively deep (head depth at base of supraoccipi- 1.0-1.6 times. Anterior fontanelle narrowly triangular, tal posterior process equal to body width. Head covered by originating half way between posterior nostrils and anterior thin skin and a thick layer of mucus, posterior half of skull margin of orbit, its broad posterior end located at about roof weakly ornamented with small closely packed tuber- level of posterior margin of orbit. Posterior fontanelle cles. Snout long, more so in larger fish, contained 2-2.9 present only in smallest specimens as an oval aperture and in head length, rounded profile in dorsal view. Upper jaw closing completely with growth. Supraoccipital posterior projecting and relatively longer in larger specimens; with process strong, broad-based (its basal width 1.2-1.4 times mouth closed premaxillary teeth broadly exposed except in length), reaching broad anterior nuchal plate; dorsally in largest specimens with much thickened lips. Anterior abruptly but smoothly rounded, not angular or keeled.