Astyanax burgerai, Zanata & Camelier, 2009

Zanata, Angela M. & Camelier, Priscila, 2009, Astyanax vermilion and Astyanax burgerai: new characid fishes (Ostariophysi: Characiformes) from Northeastern Bahia, Brazil, Neotropical Ichthyology 7 (2), pp. 175-184 : 180-182

Astyanax burgerai , new species

Figs. 6-7

Holotype. MZUSP 101245 , 53.2 mm SL, Brazil, Bahia State, Almadina, córrego Água Boa on road between Floresta Azul and Almadina, tributary of riacho Pancadinha , itself a tributary of rio Almada , 14°44’42”S 39°38’40”W, 212 m alt., 12 Feb 2008, A. M. Zanata, P. Camelier, R. Burger & A. B. A. Góes.

Paratypes. UFBA 4346 , 15 , 1 c&s, 2 R, 19.5-54.4 mm SL, collected with holotype .

Diagnosis. Astyanax burgerai can be distinguished from all other Astyanax species known from northeastern Brazilian drainages ( A. brevirhinus , A. epiagos , A. fasciatus , A. intermedius , A. jacobinae , A. lacustris , A. pelecus , A. rivularis , A. taeniatus , and A. turmalinensis ) by the presence of two vertically elongated humeral blotches (vs. only one humeral blotch, rounded or distinctly horizontally elongated in A. brevirhinus , A. lacustris and A. pelecus , and vertically elongated in A. epiagos , A. fasciatus , A. intermedius , A. jacobinae , A. rivularis , and A. taeniatus ), absence of a conspicuous and broad dark midlateral stripe, at least on anterior half of body (vs. presence in A. brevirhinus , A. fasciatus , A. intermedius , A. jacobinae , A. rivularis , A. taeniatus , and A. turmalinensis ), body highest along vertical slightly behind midlength of pectoral fin (vs. highest body depth just anterior to dorsal-fin origin in A. brevirhinus , A. fasciatus , A. lacustris , A. pelecus , A. taeniatus , and A. turmalinensis ), 31-34 lateralline perforated scales (vs. 35 or more in A. brevirhinus , A. intermedius , A. jacobinae , A. pelecus , and A. rivularis ), and two or three teeth on premaxillary outer series (vs. three, four or five in A. brevirhinus , A. fasciatus , A. jacobinae , and A. lacustris ). Astyanax burgerai can be further distinguished from A. fasciatus and A. lacustris by having 21-22 total anal-fin rays (vs. 25-34), and from A. jacobinae by having one or two maxillary teeth (vs. three teeth). This new species differs further from A. turmalinensis by having 2-3 teeth on outer premaxillary row Description. Morphometric data of holotype and paratypes presented in Table 2. Body somewhat compressed and elongate. Greatest body depth along vertical slightly behind midlength of pectoral fin. Dorsal profile of head convex from upper lip to vertical through anterior nostrils; straight to slightly convex from latter point to tip of supraoccipital spine and moderately convex from this point to dorsal-fin origin. Body profile straight and posteroventrally slanted along dorsal-fin base; straight from dorsal-fin base terminus to adipose fin, and slightly concave along caudal peduncle. Ventral profile of head and body convex on its anteriormost portion and moderately convex from region below eye to anal-fin origin. Body profile along anal-fin base straight and posterodorsally slanted. Ventral profile of caudal peduncle nearly straight to slightly concave.

Head somewhat pointed anteriorly in lateral profile; mouth terminal. Posterior terminus of maxilla trespassing vertical through anterior margin of orbit. Premaxillary teeth in two rows. Outer row with 2* (6) or 3 (8) teeth bearing 3 cusps. Inner row with 4 (1), 5* (13), teeth bearing 5 to 7 cusps. Symphyseal tooth of inner series relatively narrow, asymmetrical, with one cusp on anteromedial side, one larger central cusp and three smaller on lateral side; second teeth the larger, with 7 cusps; remaining teeth with 5 cusps. Maxilla with 1* (3) or 2 (11) broad teeth bearing 5 cusps of similar size. Dentary with 8 (1) or 9* (2) teeth decreasing gradually in size posteriorly; first to third teeth somewhat asymmetrical, with six cusps, two on anteromedial side, one median larger cusp and three smaller on lateral side; fourth and fifth teeth with 5 cusps and posterior ones with 3 cusps.

Scales cycloid; circuli absent on exposed area of scales, with few slightly divergent radii extending to posterior margin of scales. Lateral line slightly decurved anteriorly, completely pored from supracleithrum to base of caudal fin, with 31 (1), 32* (3), 33 (3), or 34 (7) perforated scales. Horizontal scale rows between dorsal-fin origin and lateral line 5 (14), not including scale of predorsal series situated just anterior to first dorsal-fin ray. Horizontal scale rows between lateral line and pelvic-fin insertion 4* (10) or 5 (4). Scales along middorsal line between tip of supraoccipital process and origin of dorsal fin 9 (1), 10* (10), 11 (2), or not ordered in a line (1). Horizontal scale rows around caudal peduncle 13* (2), 14 (11), or15 (1). Base of anteriormost anal-fin rays covered by a series of 3-6 scales.

Dorsal-fin rays ii,9 (14). Distal margin of dorsal fin somewhat rounded. Dorsal-fin origin situated at vertical approximately at or slightly posterior to the middle of standard length. Base of last dorsal-fin ray aligned with anal-fin origin. First dorsal-fin pterygiophore inserting behind neural spine of 10 th (4) vertebra. Adipose fin present. Anal-fin rays iii,18* (5) or 19 (9). Distal margin of anal fin slightly concave to nearly straight. First anal-fin pterygiophore inserting behind haemal spine of 16 th (3) or 17 th (1) vertebra. Pectoral-fin rays i,9* (1), 10 (2), 11 (6), or 12 (5). Tip of pectoral fin never reaching vertical through pelvic-fin insertion. Pelvic-fin rays i,7 (14). Caudal fin forked, lobes rounded, similar in size. Principal caudal-fin rays 10+9 (2), 10+10 (1). Eight (2) or 9 (2) dorsal procurrent caudal-fin rays, and 7 (1), 8 (2) or 9 (1) ventral procurrent caudal-fin rays. First gill arch with 6 (1) + 1 (1) + 11 (1) rakers. Vertebrae 33 (4). Supraneurals 5 (3).

Color in alcohol. Examined specimens lack guanine on body or head ( Fig. 6 ). Overall ground color tan, yellowish on ventral half of body. Head dorsum dark due to concentration of diminute dark chromatophores, as on most extension of maxilla. Infraorbitals, preopercle and opercle clearer, with sparse larger dark chromatophores. Ventral portion of head clear, except by concentration of diminute dark chromatophores on anteriormost portion. Middorsal line dark similarly to head dorsum. Small dark chromatophores homogeneously distributed over four or five dorsalmost longitudinal series of body scales; chromatophores larger on scale series immediately above lateral line. Ventral half of body with scattered dark chromatophores and abdominal region without dark pigmentation. Humeral region with two dark blotches. Anterior blotch more evident, vertically elongated, wider dorsally and situated behind first vertical scale series on rear of opercle opening; blotch bordered anteriorly and posteriorly by regions of paler coloration. Posterior humeral blotch much less conspicuous, with variable shape, situated posterior to clear area on rear of first blotch, and formed by dark chromatophores over three series of scales immediately above lateral line. A dark midlateral line extends from second humeral blotch to caudal peduncle; dark chromatophores over midlateral line usually more visible behind vertical through end of dorsal-fin base, resulting in an inconspicuous stripe, enlarged posteriorly and forming an elongated caudal blotch. All fins equally colored, with small chromatophores homogeneously distributed over membranes and borders of rays. Adipose fin with scattered small dark chromatophores. Caudal fin with base of median rays somewhat dark, as part of caudal blotch.

Color in life. Life color pattern taken from specimen barely dead and another specimen kept alive in aquarium ( Fig. 7 ). Overall body coloration silvery to pale, with golden reflexes mainly on dorsal half. Midlateral region somewhat reddish. Humeral blotches poorly visible. Caudal blotch poorly visible on specimens barely dead but well defined after several days in aquarium. Small dark chromatophores scattered over head and body. All fins pale to yellowish.

Sexual dimorphism. Small hooks over anal-fin rays present in three male specimens (39.3-53.2 mm SL), distributed over longer unbranched ray and first six branched rays; unbranched rays with four hooks and posterior rays with five to seven hooks in each ray. Hooks absent on remaining fins.

Geographic distribution and ecological notes. Astyanax burgerai is known only from córrego Água Boa, a streamlet on the road between Floresta Azul and Almadina, tributary of riacho Pancadinha, itself a tributary of rio Almada, a coastal drainage on southern Bahia, Brazil ( Fig. 4 ). The species was collected at 212 meters of altitude, in clear water stream,

running over rocky and sandy bottom, in habitat characterized by very small pools, 20-70 cm deep ( Fig. 8 ). The surrounding vegetation is composed by remains of the Atlantic Forest, with trees and shrubs. The only other syntopic species is Trichomycterus cf. bahianus .

The analysis of the stomach contents of two specimens revealed the presence of filamentous algae, fragments of arthropods, fragments of vascular plants and organic debris.

Etymology. Thename burgerai isgiveninhonorofRafaelBurger, a student who enthusiastically collected the new species.

Figures

Fig. 6. Astyanax burgerai, new species, holotype, male, MZUSP 101245, 53.2 mm SL, Brazil, Bahia State,Almadina, córrego Água Boa, rio Almada drainage.

Fig. 7. Astyanax burgerai, new species, paratype alive, male, UFBA 4346, 54.4 mm SL.

Fig. 4. Map of northeastern Brazil, showing position of type locality of Astyanax burgerai (full triangle), type locality (full circle) and other sampled sites of Astyanax vermilion (full square), new species.

Fig. 8. Type locality of Astyanax burgerai, Brazil, Bahia State, Almadina, córrego Água Boa, rio Almada drainage.