Astyanax sincora, Burger & Carvalho & Zanata, 2019

Burger, Rafael, Carvalho, Fernando R. & Zanata, Angela M., 2019, A new species of Astyanax Baird & Girard (Characiformes: Characidae) from western Chapada Diamantina, Bahia, Brazil, Zootaxa 4604 (2), pp. 369-380 : 370-375

Astyanax sincora , new species

( Figs. 1–2 )

Holotype. MZUSP 120747, 46.0 mm SL, Brazil, Bahia State, Chapada Diamantina, Mucugê, Fazenda Tremedal , córrego Tremedal , tributary of rio Paraguaçu , 13°10’22”S 41°20’53”W, 1083 m a.s.l., 27 Jun 2016, A.M. Zanata, R. Burger & G. Oliveira.

Paratypes. All from Brazil, Bahia State, Chapada Diamantina, Mucugê , rio Paraguaçu basin. UFBA 8200 , 49 , 11.7–61.5 mm SL; MZUSP 120748 , 12, 34.1–47.6 mm SL; MNRJ 48346 , 10 , 29.9 – 49.0 mm SL; ZUFMS 5276 , 10 , 33.8–46.2 mm SL, collected with holotype. UFBA 7356 , 16 , 18.6–21.4 mm SL, córrego Ibicoara, Fazenda Ibicoara , 13°12’56”S 41°19’34”W, 1070 m a.s.l., 2 May 2013 , A. M. Zanata, R. Burger, L. Oliveira & R. Abreu. UFBA 7357 , 86 , 26.9–55.7 mm SL, same locality as holotype, 2 May 2013 , A. M. Zanata, R. Burger, L. Oliveira & R. Abreu. UFBA 7363 , 14 , 22.1–50.3 mm SL, creek at Fazenda Tremedal , 13°10’23”S 41°20’46” W, 1068 m a.s.l., 2 May 2013 , A. M. Zanata, R. Burger, L. Oliveira & R. Abreu. UFBA 8201 , 10, 25.3–38.9 mm SL, rio Cap„ozinho, between Mucugê and Guiné, rio Paraguaçu basin , 12°49’36”S 41°31’03”W, 27 Jun 2016 , A. M. Zanata, R. Burger & G. Oliveira. MNRJ 26003 , 5, 33.0– 58.5 mm SL, river between Cascavel and Mucugê , BA-142, 40 km of Mucugê , 13°14’59’’S 41°26’26’’W, M. R. Britto, C. Oliveira & C. Dias, 5 Nov 2003.

Diagnosis. Astyanax sincora can be distinguished from most congeners, except A. brachypterygium Bertaco & Malabarba , A. burgerai Zanata & Camelier , A. courensis Bertaco, Carvalho & Jerep , A. cremnobates Bertaco & Malabarba , A. epiagos Zanata & Camelier , A. eremus Ingenito & Duboc, A. goyanensis (Miranda-Ribeiro) , A. guaricana Oliveira, Abilhoa & Pavanelli , A. gymnogenys Eigenmann , A. jacobinae Zanata & Camelier , A. jenynsii (Steindachner) , A. joaovitori Oliveira, Pavanelli & Bertaco , A. jordanensis Alcaraz, Pavanelli & Bertaco , A. laticeps (Cope) , A. leonidas Azpelicueta, Casciotta & Almirón , A. lorien Zanata, Burger & Camelier , A. microschemos Bertaco & Lucena , A. obscurus (Hensel) , A. ojiara Azpelicueta & Garcia , A. paranae Eigenmann , A. paris Azpelicueta, Almirón & Casciotta , A. pirabitira Lucena, Bertaco & Berbigier , A. pirapuan Tagliacollo, Britzke, Silva & Benine , A. rivularis (L̹tken), A. rupestris Zanata, Burger & Camelier , A. scabripinnis (Jenyns) , A. serratus Garavello & Sampaio , A. taurorum Lucena, Zaluski & Lucena , A. totae Haluch & Abilhoa , A. troya Azpelicueta, Casciotta & Almirón , A. turmalinensis Triques, Vono & Caiafa , and A. varzeae Abilhoa & Duboc by having a low number of branched anal-fin rays (13–17) and highest body depth approximately at vertical between midlength to final third of the pectoral-fin (vs. 21 or more branched anal-fin rays and highest body depth just anterior to the dorsal-fin origin). Astyanax sincora can be distinguished from the aforementioned congeners by having eight branched dorsal-fin rays (vs. nine or 10 branched rays, with the exception of A. goyanensis , A. guaricana , A. jenynsii , A. joaovitori , A. pirapuan , and A. serratus that rarely possess eight branched rays) and six branched pelvic-fin rays (vs. seven or eight branched rays in A. burgerai , A. courensis , A. cremnobates , A. eremus , A. guaricana , A. jenynsii , A. laticeps , A. leonidas , A. lorien , A. microschemos , A. ojiara , A. paris , A. pirapuan , A. rivularis , A. rupestris , A. taurorum , A. totae , A. troya , A. turmalinensis , and A. varzeae ). The new species differs from A. goyanensis by the presence of bony hooks in pectoral fins of males and pectoral fin never reaching pelvic fin origin (vs. absence of bony hooks and tip of pectoral fin of males reaching pelvic fin origin), from A. joaovitori by having the dark midlateral line or stripe initiating posteriorly to humeral blotch (vs. stripe initiating immediately on the rear of the upper margin of the opercle), and from A. serratus by having 30–35 scales in the longitudinal series and humeral blotch vertically elongate (vs. 36 or more scales and rounded humeral blotch).

Description. Morphometric data of holotype and paratypes in Table 1 . Body compressed and moderately elongate; highest body depth approximately at vertical through pectoral-fin midlength or final third of fin. Dorsal profile of head convex from upper lip to vertical through anterior nostrils; straight to slightly convex above eye and straight from vertical through posterior border of eye to tip of supraoccipital spine. Dorsal profile of body convex from tip of supraoccipital spine to dorsal-fin origin; straight to convex and posteroventrally slanted along dorsal-fin base; straight from end of dorsal-fin base to adipose fin and slightly concave along caudal peduncle. Ventral profile of head and body convex from lower lip to pelvic-fin origin; straight from that point to anal-fin origin; straight and posterodorsally slanted along anal-fin base, and slightly concave along dorsal and ventral profile of caudal peduncle.

Head rounded anteriorly in lateral profile. Eyes relatively large compared with head length. Mouth terminal. Posterior terminus of maxilla extending beyond vertical through anterior margin of orbit. Nostrils close to each other and separated by skin flap; anterior opening small, circular and with raised borders; posterior one more than twice in size, elongate and without raised borders. Nasal bone present. Frontals separated anteriorly, with wide fontanel; parietal fontanel large, extending from the epiphyseal bar to supraoccipital spine. Infraorbital series with five or six elements; third infraorbital distinctly developed and fourth infraorbital distinctly reduced. Parietal branch of the supraorbital canal reaching parietal bone.

Premaxillary teeth in two rows. Outer premaxillary row with 3 (4), 4* (46), or 5 (10) teeth bearing three cusps; inner row with 4* (12) or 5 (48) teeth on both contralateral bones; symphyseal tooth of inner series narrow, asymmetrical, usually without cusp on medial side, one larger central cusp and two or three smaller on lateral side; second or third tooth the largest, usually with five cusps, rarely seven cusps; last teeth smaller with three cusps. Maxilla with 1* (51) or 2 (9) teeth, usually with three cusps, rarely conical. Dentary with 7 (1), 8 (2), or 9 (1) teeth; four or five large anterior teeth usually with five or six cusps, followed by three to five smaller ones, usually conical ( Fig. 2 ).

Scales cycloid; circuli conspicuous anteriorly but absent on exposed area of scales; radii lightly divergent on posterior portion of scale. Lateral line slightly curved ventrally, with total number in longitudinal series 30 (2), 31* (4), 32 (10), 33 (28), 34 (7), or 35 (2) scales. Scales with pores on lateral line series variably; 14 specimens with completely pored lateral line, with 30 (1), 31 (1), 32 (1), 33 (9), or 34 (2) scales, remaining specimens with 12 (2), 15 (3), 16 (3), 17 (3), 21 (5), 22 (2), 23 (4), 24 (4), 25 (1), 26 (1), 27 (3), 28 (1), 29 (3), 30 (4), 31 (4), or 32 (3) pored scales followed by non-pored ones (incomplete lateral line); some specimens with pored scales interspersed with non-pored ones (discontinuous lateral line) of variable pattern. Holotype with 27 pored plus four non-pored lateral line scales. Longitudinal scale rows between dorsal-fin origin and lateral line 4 (1), 5* (56), or 6 (3). Longitudinal scale rows between lateral line and pelvic-fin origin 4* (58) or 5 (2). Scales along middorsal line between tip of supraoccipital process and origin of dorsal fin 9 (2), 10* (14), 11 (19), or 12 (2), irregular in some specimens. Base of anteriormost anal-fin rays with single scale row composed of three to five scales. Horizontal scale rows around caudal peduncle 11 (11), 12 (21), 13* (18), or 14 (12). Caudal fin with scales restricted to the base of rays. Axillary scale small or absent.

Dorsal-fin rays ii,8 (60). Distal margin of dorsal fin slightly rounded. Dorsal-fin origin situated at vertical approximately at middle of standard length. Base of last dorsal-fin ray aligned or slightly anterior to anal-fin origin. First dorsal-fin pterygiophore inserting behind neural spine of 10 th (1) or 11 th (4) vertebra. Adipose fin present. Anal-fin rays with iv* (59), 13 (1), 14 (15), 15* (32), 16 (10), or 17 (1). Distal margin of anal fin slightly concave in females and straight to slightly convex in mature males. First anal-fin pterygiophore inserting behind haemal spine of 17 th (1) or 18 th (4) vertebra. Pectoral-fin rays with i* (58), 9 (1), 10 (12), 11* (39), or 12 (6). Tip of pectoral fin usually not reaching pelvic-fin insertion. Pelvic-fin rays with i* (60), 6* (59), or 7 (1). Extension of pelvic-fin ontogenetically variable and sexually dimorphic; pelvic fin not reaching insertion of first anal-fin ray in juveniles, but reaching or almost reaching in adult males; pelvic-fin distant from insertion of first anal-fin ray in adult females. Caudal fin forked, lobes rounded, similar in size. Principal caudal-fin rays i9, 8i (5). Nine (1) or 10 (3) dorsal procurrent caudal-fin rays, and nine (2) or 10 (2) ventral procurrent caudal-fin rays.

Total vertebrae 34 (2), 35 (1), or 36 (2); Precaudal vertebrae 15 (1), 16 (3), or 17 (1); caudal vertebrae 19 (4) or 20 (1). Supraneural bones 6 (2) or 7 (1). Branchiostegal rays 4 (5). First gill arch with 9 (5) gill rakers on hypobranchial and ceratobranchial, 1 (5) raker on cartilage between ceratobranchial and epibranchial, and 5 (2) or 6 (3) rakers on epibranchial.

Color in alcohol. Overall ground color yellowish to tan, dorsal half of body darker ( Fig. 1a ). Infraorbitals with minute melanophores postioned close to the border of orbit and larger melanophores sparsely scattered on remaining area of ossifications. Opercle and preopercle with sparse melanophores, usually more concentrated on its dorsal portion. Ventral surface of head without dark pigmentation, except by a few small melanophores on its anteriormost portion. Maxilla poorly pigmented, with sparse melanophores on its proximal portion. Humeral region with a conspicuous and vertically-elongated black blotch; blotch covering three or four scales on horizontal series immediately above lateral line, tapering ventrally; anterior margin of blotch usually concave and posterior margin usually somewhat convex. Humeral blotch usually bordered posteriorly by distinct clear areas. Midlateral dark stripe usually initiating on the rear of the clear area posterior to the humeral blotch and extending to the end of caudal peduncle; in cases of initiating anteriorly and crossing the clear area on the rear of the humeral blotch, stripe distinctly narrow or just a dark line; stripe usually more evident on posterior half of body. No distinct caudal peduncle blotch present.

Longitudinal scale series of flank usually with small melanophores concentrated along their posterior margins, resulting in an inconspicuous reticulate pattern; center of scales darker on dorsal portion of body; scales on area immediately above pectoral and pelvic fins paler than surrounding areas or not pigmented; dark lines absent on myosepts above anal-fin base. Ventral surface of body not pigmented. All fins similarly colored, with scattered melanophores concentrated on margins of rays and interradial membranes; caudal fin with four or five central rays somewhat darker, with small melanophores on its borders; adipose fin with scattered small melanophores.

Color in life. Freshly collected specimens with overall silvery to yellowish coloration, with blue or green hues ( Fig. 1b ). Dorsal portion of head and body somewhat darker; belly whitish. Humeral blotch conspicuous. Midlateral stripe not discernible. Dorsal, caudal, anal, and pelvic fins reddish in mature males; females with fins yellow- or orangish. Pectoral fins yellow or hyaline. Caudal-fin with central rays somewhat dark.

Sexual dimorphism. Males of Astyanax sincora possess bony hooks on pectoral and anal fins, distinct analfin profile from females and tip of pelvic-fin rays reaching or almost reaching insertion of first anal-fin ray. Hooks present from the first or second unbranched ray up to the 12 th branched anal-fin ray and situated on distal half of rays, distributed from one or two segments before bifurcation of rays and continuing on posterior hemitrichium of each ray. Hooks somewhat curved, directed bilaterally, symmetric, and slightly longer approximately at midlength of branched portion of rays. Pectoral fin with similar dorsally or anterodorsally directed hooks, usually not furcate but it may occur in some specimens. Hooks distributed in up to first five branched rays of mature males, rarely on the unbranched ray. Up to 10 hooks observed in the unbranched and up to 17 hooks observed in the first branched ray; number of hooks decreases towards posterior rays. The smallest male with hooks measured 27.8 mm SL (UFBA 7357). Pelvic, dorsal, and caudal-fin rays without hooks.

Mature males and females can be also distinguished externally by the anal-fin profile. Border of the fin in males straight to slightly convex ( Fig. 1a ), whereas females with anterior half of the fin border concave ( Fig. 1b ). Females reach larger body sizes than males (UFBA 8200, 61.5 mm SL vs. UFBA 7363, 49.4 mm SL, respectively). Males and females also differ slightly in the length of some fins, e.g., pelvic and anal fins. Particularly, the tip of the pelvic fin in adult males reach or almost reach the insertion of the first anal-fin rays ( Fig. 1a ), a condition distinct from adult females that have the tip of the pelvic fin distinctly distant from anal-fin insertion ( Fig. 1b ). Gill glands ( Burns & Weitzman, 1996) were not found macroscopically on first gill arch of both sexes.

Distribution. Astyanax sincora is known from very small tributaries of the upper rio Paraguaçu basin, within the Chapada Diamantina domain, Bahia, Brazil ( Fig. 3 ).

Habitat and ecological notes. Astyanax sincora has a very restrict distribution, so far known from three short, 8–28 km long creeks, running from the western slopes of Chapada Diamantina to the main channel of rio Paraguaçu, at approximately 1000 m a.s.l. ( Fig. 4 ). These creeks have a maximum depth of one meter, and a maximum width of 1.5 m, presenting muddy, stony or sandy bottoms, and moderate water flow. The riparian vegetation is mainly composed by grass and coffee plantations. Astyanax sincora is apparently the unique fish species inhabiting the localities where it was sampled. All streams where A. sincora occurs are dammed at various points, possessing dry sections along their entire courses.

The analysis of stomach contents of three specimens of A. sincora revealed the presence of allochthonous and autochthonous items, composed by filamentous algae, fragments of vascular plants, organic debris, and fragments of adults of terrestrial insects ( Hymenoptera , Formicidae ).

Etymology. The specific epithet “ sincora ” is a reference to Serra do Sincorá, an orographic system situated on the central portion of Chapada Diamantina, Bahia State, extending 80 km along a north-south axis and reaching up to 2,000 m high. The new species occurs at the base of the western slopes of the Serra do Sincorá. A name in apposition.

Figures

FIGURE 1. Astyanax sincora, Brazil, Bahia State, Mucugê, Fazenda Tremedal, córrego Tremedal, tributary of rio Paraguaçu: (a) holotype, male, MZUSP 120747, 46.0 mm SL; (b) live paratype, female, UFBA 7357, 54.9 mm SL.

FIGURE 2. Upper and lower jaws of Astynax sincora, paratype, UFBA 7357, 37.3 mm SL, lateral view, left side.

FIGURE 3. Map of the rio Paraguaçu basin, Bahia, eastern Brazill showing collection localities of Astyanax sincora. Black star = type locality; white stars = paratypes localities.

FIGURE 4. Type locality of Astyanax sincora, Brazil, Bahia State, Mucugê, Fazenda Tremedal, córrego Tremedal, tributary of rio Paraguaçu.