Probolodus oyakawai, Santos & Castro, 2014

Santos, Osmar & Castro, Ricardo M. C., 2014, Taxonomy of Probolodus Eigenmann, 1911 (Characiformes: Characidae) with description of two new species, and comments about the phylogenetic relationships and biogeography of the genus, Neotropical Ichthyology 12 (2), pp. 403-418 : 409-411

Probolodus oyakawai , new species

Figs. 1 ; 5-6

Probolodus heterostomus, Eigenmann, 1911: 164 [in part], paratypes. - Eigenmann, 1915: 20-22 [in part]. Paratypes [CM 2975, 2, 78-81 mm SL]: P. heterostomus ( Brazil, São Paulo, Iporanga, rio Ribeira de Iguape basin). - Sazima, 1977: 510, 512 [in part] (distribution and ecology). - Bizerril, 1994: 58, 65 [in part] (distribution and identification key). -Bizerril & Lima, 2000:103-110 (list). - Lima et al., 2003: 154 [in part] (type-material, type locality and distribution). Oyakawa et al., 2006: 45, 156-157 [in part] (distribution, citation, and biology). - Buckup et al., 2007: 61 [in part] (type locality and distribution). - Menezes et al., 2007: 105 [in part] (type locality; distribution; systematic and ecology).

Holotype. MZUSP 114013 , 40.6 mm SL, Brazil, São Paulo, município de Iporanga, rio Ribeira de Iguape basin, 24°34’22"S 48°33’34"W, 20 Apr 1998, O. T. Oyakawa, V. Garutti, M. T. Piza Ragazzo & C. Ragazzo.

Paratypes. All specimens from Brazil. São Paulo State : FMNH 54330 [ CM 2975 ], 2, 61- 63 mm SL, município de Iporanga, rio Ribeira de Iguape basin ; MZUSP 35928 , 2 , 43.6-52.1 mm SL, município de Miracatú, Jaraçatiá, rio Ribeira de Iguape basin, rio Grande, tributary of the rio São Lourenço , 24°16’59"S 47°27’00"W ; MZUSP 38809 , 3 , 44.7-58.5 mm SL, município de Iguape, rio Ribeira de Iguape basin, rio do Espraiado, southern limit of the Reserva Ecológica da Jureia , 24°42’S 47°33’W ; MZUSP 53472 , 3 , 32.5- 37.9 mm SL, município de Pariquera-Açu, rio Ribeira de Iguape basin, rio Jacupiranga , irrigation canal of the CODASP (CEDAVAL), km 460 of the BR-116, 24°36’31"S 47°53’48"W ; MZUSP 53499 , 12 , 21.4-64.3 mm SL, município de Jacupiranga, rio Ribeira de Iguape basin, stream that goes through the BR-116, km 470, near the town of Jacupiranga , 24°39’S 47°58’00"W (2 c&s, 31.7-64.3 mm SL) ; MZUSP 53549 , 4 , 34.6-41.8 mm SL, município de Iporanga, rio Ribeira de Iguape basin, tributary of the rio Betari on the road to the Santana cave , 5 km from the town of Iporanga , 24°35’00"S 48°36’59"W ; MZUSP 55006 , 4 , 34.6-37.9 mm SL, município de Iporanga, rio Ribeira de Iguape basin, mouth of the rio Iporanga , 24°34’22"S 48°33’34"W (1 c&s, 37.9 mm SL) , collected with holotype ; MZUSP 64774 , 1 , 56.5 mm SL, município de Sete Barras, Ribeira de Iguape basin, mouth of the rio Saibadela, at the limits between the parks Intervales and Carlos Botelho , 24°14’14"S 48°03’09"W ; MZUSP 8003 , 2 , 31.5-58.5 mm SL, município de Iguape, rio Ribeira de Iguape basin, rio Branco da Serra, tributary of the rio Espraiado , 24°24’38"S 47°25’36"W ; MZUSP 84674 , 4 , 35.2-39.8 mm SL, município de Sete Barras, rio Ribeira de Iguape basin, fazenda Brasban, rio Ipiranga , 24°10’46"S 47°51’14"W ; ZUEC 1693 , 1 , 43.6 mm SL, município de Iguape, rio Ribeira de Iguape basin, tributary of the rio Despraiado , 24°42’01"S 47°32’58"W ; ZUEC 1694 , 1 , 48.8 mm SL, município de Iguape, rio Ribeira de Iguape basin, tributary of the rio Despraiado , 24°42’01"S 47°32’58"W .

Diagnosis. Probolodus oyakawai differs from its two congeners, P. heterostomus and P. sazimai (new species) by the following characteristics: the base of the large epural not leaning against the urostyle bone (vs. the base of the large epural in contact, not fused the urostyle) ( Fig. 6a ); first and second infraorbitals contacting but not overlapping (vs. relationship with overlapping or leaning against) ( Fig. 6b ); posterior portion of the maxilla extended in relation to median portion (vs. posterior portion of the same width than median portion) ( Fig. 1b ); anterior extension of nasal reaching the lateral projection of mesethmoid (vs. outpacing the end of the projection of mesethmoid). It may be further separated from P. heterostomus by three attributes: 41-43 perforated scales on the lateral line (vs. 45-56 perforated scales); 14-16 scale series around the caudal peduncle (vs. 18-21 scale series around the caudal peduncle); body relatively shorter, with 33-34 totals vertebrae (vs. 34-35 totals vertebrae).

Description. Morphometrics of types presented in Table 1 . Body moderately compressed and deep, less so in individuals of less than 150 mm SL, greatest body depth within region delimited anteriorly by vertical through insertion of pelvic fin and posteriorly by vertical through origin of dorsal fin. Average body depth variable among population samples, but with broad overlap in ranges among examined samples. Dorsal profile of head distinctly convex from margin of upper lip to vertical through posterior nostril, straight to very slightly convex from latter point to tip of supraoccipital spine. Dorsal profile of body moderately convex from tip of supraoccipital spine to origin of dorsal fin, straight and posteroventrallyslanted along base of dorsal fin, straight to slightly convex from posterior terminus of base of dorsal fin to adipose fin, and slightly concave along caudal peduncle. Broad middorsal ridge present along predorsal region of body, with ridge less obvious anteriorly. Dorsal region of body between posterior terminus of dorsal fin and adipose fin transversely rounded overall, but slightly flattened middorsally in some individuals. Ventral profile of head sligtly convex anteriorly from margin of lower lip approximately to vertical through anterior nares, then straight from that point to vertical through posterior margin of eye. Ventral profile of body convex to insertion of pelvic fin, nearly straight but slightly posteroventrally-aligned from that point to origin of anal fin, straight to slightly convex and posterodorsally-slanted along base of anal fin, and slightly concave along caudal peduncle. Prepelvic region of body somewhat flattened transverselly.

Head obtusely rounded anteriorly in lateral profile. Mouth terminal. Upper jaw with maxilla distinctly posteroventrallyangled relative to ventral margin of premaxilla and extending ventral of orbit to point somewhat short of, or reaching, vertical through anterior margin of pupil. Nares of each side of head very close together; anterior opening circular, posterior crescent-shaped with distinct flap between nares. Eye relatively large and lacking distinct adipose eyelid. Median fronto-parietal fontanel extending from mesethmoid to supraoccipital spine. Width of fontanel approximately onefifth distance across bony interorbit. Infraorbital series complete with third infraorbital by far largest.All infraorbitals carrying laterosensory canal segments proximate to margin of orbital rim. Supraorbital absent. Branchiostegal rays four. Gill-rakers long and setiform; 11-13+1+7-8 rakers present on first gill-arch.

Teeth on premaxillary, maxillary, and dentary in one row. Premaxilla with three (37) teeth [three] somewhat directed outward; each tooth with three points in angles of a nearly isosceles triangle; middle point, which is also the anterior one, much larger. Maxilla with two to seven (commonly four) teeth [four] with two cusps of similar size, first two or three directed outward. Dentary, mostly, with five large teeth, first three directed outward, fourth and fifth tricuspidate, and one or more smaller ones following it, directed upward; larger teeth of lower jaw heavy, conical, with a minute cusp on each side; in overall, dentary has five to seven (commonly six) tricuspidate or biscupidate teeth [six].

Scales cycloid, relatively small, and firmly implanted. Lateral line decurved anteriorly approximately to vertical through origin of dorsal fin, then slightly posterodorsallyangled to caudal peduncle, and then running horizontally to terminus of scale series. Lateral line completely pored from supracleithrum to base of caudal fin and followed posteriorly by assified tubular extension running along lateral margin of membrane joining middle rays of caudal fin. Lateral-line scales 41 (2), 42 (29), or 43 (3) [42]; scales in transverse series from origin of dorsal fin to lateral line 7 (5), 8 (29), or 9 (1) [8]; scales in transverse series from insertion of pelvic fin to lateral line 7 (33) or 8 (1) [7]; scales in transverse series from origin of anal fin to lateral line 7 (24) or 8 (11) [7]; scales along middorsal line between tip of supraoccipital process and origin of dorsal fin 12 (35) or 13 (2) [12]; scales along middorsal line between posterior termination of base of dorsal fin and adipose fin 13 (2), 14 (7), 15 (27), or 16 (1) [15]; horizontal scale rows around caudal peduncle 14 (25) or 16 (7) [14]. Vertebrae 33 (n = 4) or 34 (n = 19) [34].

Dorsal-fin rays ii,9 (37) [ii,9].Anal-fin rays iv (12) or v (25), 22 (1), 23 (2), 24 (7), 25 (18), 26 (6), or 27 (3) [v,27]. Pectoral-fin rays i,10 (1), i,10,i (6), i,11 (18), i,11,i (8), or i,12 (4) [i,11,i]. Pelvic-fin rays i,7 (31), i,7,i (5) [i,7]. Principal caudal-fin rays i,17,i (37) [i,17,i].

Dorsal-fin margin distally rounded to slightly truncate; first unbranched ray approximately 40-50% length of second unbranched ray. Dorsal-fin origin situated along vertical located approximately at middle of SL. Origin of adipose fin located slightly anterior of vertical through posterior terminus of base of anal fin. Profile of adpressed pectoral fin distinctly acute. Tip of pectoral fin extending approximately to vertical through insertion of pelvic fin. Profile of expanded pelvic fin pointed, with first branched ray either longest in fin or subequal to unbranched ray. Insertion of pelvic fin located distinctly anterior to vertical through origin of dorsal fin. Tip of adpressed pelvic fin extending approximately to vertical through insertion of anal fin. Some larger, apparently male, specimens with posteriorly-directed hooks along posterior margins of second through seventh pelvic-fin rays; hooks rarely also present on first ray. Hooks limited to posterior branch of hook-bearing rays. Each hook-bearing segment typically with one hook, although two hooks occasionally present on some segments. Distal margin of anal fin slightly concave in which fourth or fifth unbranched and first and second branched rays longest and subequal or first through third branched rays longest with subsequent branched rays gradually decreasing in length. Some larger, apparently male, individuals with hooks present on various rays gradually of anal fin. Hooks most often arise along posterior margin of posterior branch of second through seventh branched rays. Hooks extending onto unbranched segments of some rays. Caudal fin forked, with distal margins of lobes obtusely pointed.

Color in alcohol. Overall ground color of body in specimens fixed in formalin yellowish brown. Guanine remaining on lateral and ventral portions of head and on ventral and, to a variable degree, lateral surfaces of body. Snout and dorsal portion of head relatively dark. Middorsal and immediately adjoining portions of body relatively dark. Distinct, wedge-shaped, ventrally-attenuated humeral blotch with irregular margins extending from approximately five scales dorsal of lateral line to about two scales ventral of lateral line. Pigmentation of humeral blotch typically most intense in region dorsal of lateral line, with pigmentation of remaining ventral portion of blotch variably lighter, but still quite obvious. Dark midlateral pigmentation more conspicuous on portion of body beginning at vertical through anterior portion of dorsal fin, with stripe widening posteriorly on caudal peduncle into distinct, horizontally-elongate, ovoid blotch. Pigmentation of blotch more intense than that of remainder of stripe. Chromatophores of dorsal portion are concentrated at the base and middle region of the scales, its margins being free of chromatophores. Region below the lateral line decreases the concentration of chromatophores, and, between the anal fin and caudal peduncle, sparse chromatophores are present in greater proportion.

Dorsal, anal, and caudal fins with interradial membranes covered by small dark chromatophores, with chromatophores often more concentrated proximate to margins of fin rays. Dark pigmentation on caudal fin more intense along middle fin-rays in most specimens and forming stripe variably continuous anteriorly with midlateral dark blotch on caudal peduncle. Anal fin with unbranched rays and all branched rays pigmented. Distal half of remainder of fin with dark chromatophores in all individuals, with fields of chromatophores extending nearly to base of fin membranes. Adipose fin lightly colored overall, but often freckled with small dark spots. Pectoral and pelvic fins with small, dark spots located both along fin-ray margins.

Distribution. Probolodus oyakawai is known to occur in the rio Ribeira de Iguape basin, southeastern Brazil ( Fig. 2 ).

Ecological notes. Ctenoid and cycloid fish scales were observed in the stomach contents of three P. oyakawai specimens (MZUSP 53499, 2, 31.7-64.3 mm SL; MZUSP 55006, 1, 37.9 mm SL). No other item could be identified, possibly due to their advanced state of decomposition.

Etymology. The species name, oyakawai , is in honor of Osvaldo T. Oyakawa from MZUSP, the collector of many of the specimens that served as the basis of this paper, in appreciation of his major contributions to our knowledge of the fishes of the rio Ribeira de Iguape basin.

Remarks. Probolodus oyakawai has been previously cited as P. heterostomus by various authors who have studied specimens collected in the rio Ribeira de Iguape basin (see synonymy). However, as shown on the item “Ecological notes”, P. oyakawai also shows preference by fish scales. Thus, as hypothesized by Sazima (1977), Astyanax fasciatus is not found over the entire range of Probolodus , being probable that in other drainages there is an association with other similar species of Astyanax . In the rio Ribeira de Iguape basin, A. ribeirae is a likely candidate, as Deuterodon iguape , which also have the general appearance of Astyanax ( Sazima, 1977; Oyakawa et al., 2006).

Figures

Fig. 1. Probolodus oyakawai, MZUSP 53499, paratype, 64.3 mm SL, teeth:a) Left premaxilla, anterior view; b) Left maxilla, lateral view; c) Left dentary, medial view. Scale bars = 1 mm.

Fig. 5. Probolodus oyakawai, holotype, MZUSP 114013, 40.6 mm SL, Brazil, São Paulo, município de Iporanga, rio Ribeira de Iguape basin.

Fig. 6. Probolodus oyakawai: a) caudal skeleton, MZUSP 55006, paratype, 36.8 mm SL, lateral view.EPU:epurals, HPU 1-5: hypurals, URO: urostyle; b) infraorbital series, MZUSP 53499, paratype, 64.3 mm SL, lateral view. IO 1-6: first to sixth infraorbitals. Scale bars = 1 mm.

Fig. 2. Geographic distribution of Probolodus oyakawai (squares), P. heterostomus (circles), and P. sazimai (triangle); star indicates type locality. 1) rio Ribeira de Iguape, 2) rio Tietê, in upper rio Paraná basin, 3) rio Paraíba do Sul, 4) rio Itapemirim, 5) rio Doce, 6) rio Mucuri, 7) rio Jequitinhonha. Symbols may represent more than one locality.