Hypostomus multidens, Jerep & Shibatta & Zawadzki, 2007

Jerep, Fernando C., Shibatta, Oscar A. & Zawadzki, Cláudio H., 2007, A new species of Hypostomus Lacépède, 1803 (Siluriformes: Loricariidae) from the upper rio Paraná basin, Southern Brazil, Neotropical Ichthyology 5 (4), pp. 435-442 : 436-440

Hypostomus multidens , new species

Fig. 1

Holotype. MZUEL 4712, 195.4 mm SL, Brazil, State of Paraná, Londrina, distrito de Maravilha, rio Tibagi basin, rio Taquara , at its mouth, 23º30’51’’S / 50º57’18’’W, 31 Jul 2006; W. Galves et al.

Paratypes. ANSP 187121 , (2) 184.4-193.2 mm SL, Brazil, State of São Paulo, Cândido Mota, rio Paranapanema , 1992 . MZUEL 4497 , (2) 177.3-185.9 mm SL, same data as holotype. Brazil: State of Paraná : MZUEL 152 , (1) 155.4 mm SL, Sertanópolis, rio Tibagi , 17 Feb 1991 . MZUEL 153 , (1) 131.3 mm SL, Sapopema, rio Tibagi , 25 Feb 1991 . MZUEL 154 , (1) 163.5 mm SL, Londrina, rio Tibagi basin, Ribeirão Cambé , 06 Oct 1990 . MZUEL 2100 , (1) 109.8 mm SL, Porecatu, rio Paranapanema , 1992 . MZUEL 2101 , (1) 197.5 mm SL, rio Paranapanema , 1992 . MZUEL 3388 , (2) 140.9-143.8 mm SL, rio Pardo , 12 Nov 2000 ; S. Britto. MZUSP 93883 , (2) 149.3-171.0 mm SL, Porecatu, rio Paranapanema, 1992. NUP 2561, (5) 96.3-155.4 mm SL, Guaíra , rio Paraná, Itaipu Reservoir , 25º00’S / 54º15’W, 1983-1993. NUP 4821, (2) 160.0- 169.3 mm SL, Tibagi , rio Tibagi , 18 Feb 2002 ; A. M. Geahl. NUP 4829, (1) 184.3 mm SL, Guaíra , rio Paraná, 27 Jul 2002 ; T. Becker. State of São Paulo: LISDEBE 1966, (2) 181.7-188.8 mm SL, Piraju, rio Paranapanema , 10 Jul 2000 ; J. C. Garavello, A. K. Oliveira. LISDEBE 1967, (1) 160.4 mm SL, Ourinhos, rio Paranapanema , 29 Nov 2004 ; J. C. Garavello, A. K. Oliveira, A. S. Soares. LISDEBE 1968, (1) 145.8 mm SL, Ourinhos, rio Paranapanema , 23º06’17’’S / 49º45’46’’W, 16 May 2006 ; J. C. Garavello, F. Apone , H . R. Varella .

Diagnosis. Hypostomus multidens is distinguished from all remaining congeners with light spots on a darker background by two independent characters: the presence of teeth with two symmetrical cusps (vs. two asymmetrical cusps in H. albopunctatus , H. lexi , H. margaritifer , H. meleagris , H. microstomus , H. regani , H. scaplyceps , H. strigaticeps , H. tietensis , and H. variipictus ), and a high tooth number in each mandibular ramus (122-267, mean = 196.8; vs. 127 teeth at most, in H. ternetzi , the congener with highest tooth number in each mandibular ramus from upper rio Paraná basin).

Description. Counts and proportional measurements presented in Table 1. Dorsal surface of body covered with plates except for narrow area around dorsal fin insertion. Body gradually narrower from cleithrum to caudal fin. Dorsal profile of body convex, rising in straight line from snout tip to supraoccipital, then as a ridge until dorsal-fin origin; descending from this point to caudal-fin base. Body mostly ovoid in cross-section, and slightly flattened ventrally. Caudal peduncle robust and roughly ovoid in cross-section, slightly flattened on ventral portion with shallow concave area posterior to anal-fin insertion, more compressed caudally. Greatest body depth at dorsal-fin origin. Ventral surface of head usually naked, sometimes with platelets anterior to gill openings; abdomen covered with minute platelets at line of pectoral girdle and anterior of urogenital opening, some specimens with plated area expanded to center of abdomen.

Head broad, anterior profile roundish or moderately roundish in dorsal view. Snout depressed with naked area without odontodes on its tip. Three slightly longitudinal ridges between orbits and snout tip, lateral ridges more prominent. Dorsal region between orbits concave; upper margin of orbits elevated. Supraoccipital bordered posteriorly by first predorsal plate, its dorsal surface convex with ridge that increases through predorsal plates until dorsal-fin origin. Dorsal plates between end of dorsal-fin base and first unpaired preadipose plate flattened; first ones without odontodes on their median line. Mid-dorsal and medial series of plates more keeled until middle of dorsal-fin base. Mid-ventral series of plates keeled until beginning of ventral series of plates. First anal-fin proximal radial exposed, forming flat plate anterior to first anal-fin ray. Most lateral body plates with weak odontodes on posterior border.

Eye moderately large, dorsolaterally placed. Iris with minute dorsal flap covering pupil. Mouth with short, narrow buccal papilla. Oral disc wider than longer and well developed, occupying most of ventral surface of head. Lower lip reaching gill opening and covered with minute papillae, that decrease in size towards lips edge. Maxillary barbel short, coalesced with lower lip and ornamented with small papillae. Teeth thin, bicuspid with symmetrical cusps, in high number and very small size; slightly curved inwards ( Fig. 2 ). Opercular region not very mobile, with few hypertrophied odontodes. Cleithrum exposed and in contact with ventral border of pteroticsupracleithrum, pointed cleithral process extending above pectoral-fin insertion.

Nuchal plate present; dorsal-fin spinelet present and locking mechanism functional. Dorsal-fin origin at vertical line halfway from pectoral to pelvic-fin insertions. Last branched dorsal-fin ray reaching adipose-fin spine. Dorsalfin spine moderately flexible on distal portion. Adipose fin present and slightly curved, preceded by unpaired pre-adipose azygous plates. Pectoral-fin spine slightly curved, with hypertrophied odontodes curved forward on its distal tip. First and second branched rays as long as spine. Subsequent branched rays gradually decreasing in size. Posterior margin of pectoral fin straight, surpassing about one third of pelvic fin when adpressed. Pelvic-fin spine reaching first half of anal fin when adpressed, covered with minute odontodes ventrally and laterally. Posterior margin of pelvic fin slightly roundish. First anal-fin ray unbranched, reaching sixth plate after its origin. Distal profile of caudal fin concave, lower lobe longer than upper.

Color in alcohol. Ground color of dorsal surface of head and body brown or grayish brown; pale yellow ventrally. Dorsal surface of head with blotches slightly smaller and closer to each other than those on posterior portion of body. Dorsum and flanks covered with light roundish blotches, equally spaced and with almost pupil size. Blotches present on fins, including interradial membranes. Ventral margin of head and outer portion of upper lip homogeneously light brownish; ventral portion of caudal peduncle dusky. Spines of dorsal, pectoral, pelvic, anal and caudal fins grayish brown ( Fig. 3 ).

holotype).

Color in life. Ground color of upper surface of head and body black or grayish black; pale gray ventrally. Blotch color ranges from vibrant yellow to orange.

Distribution. Hypostomus multidens is known from several localities in the rio Paranapanema basin in the states of São Paulo and Paraná. It was also found in the rio Paraná in the transition from rapid to still waters at the beginning of the Itaipú Reservoir lake in the city of Guaíra ( Fig. 4 ).

Ecological notes. Specimens of Hypostomus multidens were so far found in large rivers, and are usually collected in low number, justifying their rarity in museum collections. We have recently conducted a survey on its type-locality (rio Taquara) and only three specimens were caught, representing 3.7% of all Hypostomus specimens collected. The other loricariid species collected with Hypostomus multidens were: Hypostomus ancistroides , H. hermanni , H. iheringii , H. margaritifer , H. regani , H. strigaticeps , Loricaria prolixa Isbrücker & Nijssen, 1978 and Megalancistrus parananus (Peters, 1881) .

Etymology. The specific epithet multidens (Latin) is given in allusion to the high number of teeth (multus, many + dens, teeth).

Figures

Fig. 1. Hypostomus multidens, holotype, MZUEL 4712, 195.4 mm SL, Brazil, State of Paraná, Londrina, distrito de Maravilha, rio Tibagi basin, rio Taquara.

Fig. 2. SEM photographs of Hypostomus multidens left dentary teeth. Partial ventral view of dentary (a). Ventral view of emergent teeth rows (b). Lateral view of teeth symmetrical cusps (c). Frontal view of tooth crown with symmetrical cusps (left), and lateral view of tooth crown with partially broken cusp (d). All photographs were taken from the paratype MZUEL 4497, 177.3 mm SL, same data as holotype.

Fig. 3. Color pattern of Hypostomus multidens, paratype, MZUEL 3388, 140.9 mm SL, Brazil, State of São Paulo, rio Pardo.

Fig. 4. Southeastern portion of South America showing distribution of Hypostomus multidens in the upper rio Paraná basin (star = type-locatily 23º30’51’’S/50º57’18’’W). Each dot can represent more than one locality or lot.