Astyanax varii, Zanata & Burger & Vita & Camelier, 2019

Zanata, Angela Maria, Burger, Rafael, Vita, George & Camelier, Priscila, 2019, A new species of Astyanax (Characiformes: Characidae) from the rio de Contas basin, Bahia, Brazil, Neotropical Ichthyology 17 (3), pp. 1-10 : 2-7

Astyanax varii , new species

urn:lsid:zoobank.org:act:2C8775FD-4CA7-4D0B-8C9D-C338A88DFEC2

Figs. 1–3 ; Tab. 1

Astyanax sp. 6.— Camelier, Zanata (2014):686, tab. 1 [listed; species from the Northeastern Mata Atlântica freshwater ecoregion].

Astyanax sp.— Barreto et al. (2018): 1158 [citation; co-occurence with Nematocharax varii ].

Holotype. MZUSP 121062 , 41.4 mm SL, Brazil, Bahia, Ubaitaba, rio Coricó in Fazenda Progresso, near the road BR- 330, lower rio de Contas basin, 14°14’50”S 39°22’39”W, 65 m above sea level (a.s.l.), 13 Feb 2008, A. M. Zanata, R. Burger, P. Camelier & A. B. A. Góes.

Paratypes. All specimens from Brazil, Bahia, rio de Contas basin. MCP 54205, 10 , 31.9–40.3 mm SL ; UFBA 8405 , 16 , 22.2–41.4 mm SL, 2 c&s 35.1 -36.7 mm SL, rio Água Suja on road BA-148, border between Abaíra and Jussiape, upper rio de Contas basin, 13°22’7.8”S 41°40’01”W, 545 m a.s.l, 18 Jun 2017, A. M. Zanata, R. Burger & G. V. Oliveira . MZUSP 112058 , 6 , 21.4 –34.0 mm SL, rio Gongogi on the border between Itajibá and Ibicuí municipalities, lower rio de Contas basin, 14º21’16.5”S 39º46’23.9”W, 164 m a.s.l, 13 Aug 2012, J. L. O. Birindelli, F. C. P. Dagosta & M. V. Loeb . MZUSP 125529 , 10 , 30.3–44.3 mm SL ; UFBA 4515 , 14 , 26.2–41.3 mm SL, collected with the holotype . MZUSP 125530 , 24 , 34.1–40.3 mm SL; NUP 21946, 10, 26.0– 36.8 mm SL ; UFBA 8380 , 49 , 22.8 –41.0 mm SL, 2 c&s 34.5–41.0 mm SL, Jussiape, Caraguataí, rio Água Suja at Balneário Rio da Barra , upper rio de Contas basin, 13°24’14.5”S 41°38’7.8”W, 529 m a.s.l., 18 Jun 2017, A. M. Zanata, R. Burger & G. V. Oliveira . UFBA 8450 , 4 , 24.8–39.5 mm SL, rio Água Suja , on road BA-148, between Abaíra and Jussiape, upper rio de Contas basin, 13°24’35.4”S 41°37’60”W, 531 m a.s.l., 5 Mar 2017, A. M. Zanata & R. Burger . UFBA 7046 , 3 , 28.8–33.2 mm SL, Dário Meira, rio Gongogi under bridge in Dário Meira , lower rio de Contas basin, 14º26’12”S 39º54’13.4”W, 180 m a.s.l., 12 Dec 2011, A. M. Zanata, P. Camelier, J. O. Birindelli, R. Burger & B. Sardeiro .

Diagnosis. Astyanax varii can be distinguished from most congeners, except A. brachypterygium Bertaco & Malabarba , A. brucutu , A. cremnobates Bertaco & Malabarba , A. epiagos , A. eremus Ingenito & Duboc , A. gymnogenys Eigenmann , A. rupestris Zanata, Burger & Camelier , A. taeniatus (Jenyns) , A. totae Haluch & Abilhoa , and A. varzeae Abilhoa & Duboc , by having the distal margin of third infraorbital distinctly separated from vertical and horizontal limbs of preopercle ( Fig. 2 ), leaving a broad area without superficial bones (vs. margins of the third infraorbital close to the limbs of preopercle, with narrow or no space between the two bones). The new species differs from the aforementioned species by having three horizontal series of scales from the lateral line to the pelvic-fin origin (vs. four or more series of scales) and by having small bony hooks on all fins of mature males (vs. bony hooks absent or not present on all fins of mature males). Astyanax varii also differs from the species listed above by having highest body depth approximately at vertical through dorsal-fin origin (vs. body deepest on a vertical through middle or posterior portion of pectoral fin in A. brachypterygium , A. cremnobates , A. epiagos , A. eremus , A. gymnogenys , A. rupestris , A. totae , and A. varzeae ), five horizontal series of scales from the dorsal-fin origin to the lateral line (vs. six or more in A. brachypterygium , A. brucutu , A. cremnobates , A. eremus , A. rupestris , A. totae , A. taeniatus , and A. varzeae ), 14 horizontal scale rows around caudal peduncle (vs. 15 or more in A. brachypterygium , A. eremus , A. gymnogenys , and A. totae ), and 34–37 pored lateral line scales (vs. 38 or more in A. eremus , A. gymnogenys , and A. taeniatus ).

Description. Morphometric data of the holotype and paratypes are given in Tab. 1 . Body compressed and elongate; highest body depth approximately at vertical through dorsalfin origin. 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. Dorsal profile of body nearly straight to slightly convex from tip of supraoccipital spine to dorsal-fin origin; straight and posteroventrally slanted from dorsal-fin origin to adipose fin and slightly concave or nearly straight along caudal peduncle. Ventral profile of head usually straight to slightly convex from anterior tip of dentary to isthmus. Ventral body profile slightly convex from isthmus to anal-fin origin; straight and posterodorsally slanted along anal-fin base and nearly straight to slightly concave along caudal peduncle.

Head somewhat pointed to rounded anteriorly in lateral profile. Mouth terminal; upper jaw similar in length anteriorly or slightly longer than lower jaw. Posterior terminus of maxilla extending beyond vertical through anterior margin of orbit. Infraorbital series moderately developed; ventral margin of third infraorbital falling distinctly short from horizontal limb of preopercle and leaving a relatively broad area without superficial bones ( Fig. 2 ). Number of infraorbitals variable, with 4(1) or 6(2) ossifications. One specimen with four elements on one side of head (UFBA 8380, 41.0 mm SL) apparently presenting infraorbitals 1 and 2 as independent elements, 3+4+5 fused resulting in one element, and infraorbital 6 independent. Supraorbital absent.

Premaxillary teeth in two rows ( Fig. 3 ). Outer row with 2(1), 3*(24), or 4(5) teeth bearing 3 or 5 cusps. Inner row with 5*(30) teeth usually bearing 7 cusps, rarely 5; second tooth the largest, with 7 cusps; last tooth with 5 or 7 cusps; symphyseal tooth of inner series asymmetrical, with 1 or 2 cusps on anteromedial side, one larger central cusp and three smaller on lateral side. Maxilla with 2(7), 3*(17), or 4(6) teeth bearing 5 to 7 cusps. Dentary with 8(8), 9(7), 10*(15), or 11(5) teeth decreasing gradually in size and number of cusps posteriorly; symphyseal tooth symmetrical with 7 cusps, followed by teeth with 5 or 6 cusps and posteriormost teeth with 3 cusps.

Scales cycloid; circuli conspicuous anteriorly but absent on exposed area of scales; few parallel radii extending to posterior margin of scale. Lateral line slightly decurved ventrally, with 34(3), 35(7), 36*(17), or 37(2) perforated scales, continuous from supracleithrum to caudal-fin base. Longitudinal scale rows between dorsal-fin origin and lateral line 5*(30). Longitudinal scale rows between lateral line and pelvic-fin insertion 3*(30). Scales along middorsal line between tip of supraoccipital process and origin of dorsal fin 9(3), 10(8), 11*(15), or irregular (4). Horizontal scale rows around caudal peduncle 14*(29). Base of anteriormost anal-fin rays with single scale row composed of 4 or 5 scales. Axillary scale absent. Caudal fin not scaled.

Dorsal-fin rays ii, 9*(30). Distal margin of dorsal fin straight or slightly rounded. Dorsal-fin origin located approximately at middle of standard length and posterior to vertical through pelvic-fin origin. Base of last dorsal-fin ray aligned with analfin origin. First dorsal-fin pterygiophore inserting behind neural spine of 9 th (3) or 10 th (1) vertebra. Adipose fin present. Anal-fin rays iii(23), 17(3), 18*(7), 19(15), or 20(5). Distal margin of anal fin concave. First anal-fin pterygiophore inserting behind haemal spine of 16 th (2) or 17 th (2) vertebra. Pectoral-fin rays i(30), 10(1), 11*(15), or 12(13). Tip of pectoral fin not reaching vertical through pelvic-fin insertion. Pelvic-fin rays i,7*(30); tip of pelvic fin not reaching first anal-fin insertion. Caudal fin forked, lobes pointed, similar in size. Principal caudal-fin rays 9+9(1), 9+10(2), or 9+11(1). Nine(1) or 11(3) dorsal procurrent caudal-fin rays and 7(1) or 10(3) ventral procurrent caudal-fin rays.

Total vertebrae 35(3) or 36(1). Precaudal vertebrae 15(3) or 16(1); caudal vertebrae 19(1) or 20(3). Supraneurals 4(2) or 5(2). Branchiostegal rays 4(2). First gill arch with 5(4) gill rakers on epibranchial, 8(4) on hypobranchial and ceratobranchial, and 1(4) on cartilage between ceratobranchial and epibranchial.

Color in alcohol. Overall ground color pale yellow or light brown ( Fig. 1a ). Guanine restricted to infraorbitals, preopercle, and opercle. Dorsal part of head moderately dark anteriorly and usually darker on posterior half; presence of two large black rounded blotch on posterior part of head in some specimens. Small melanophores sparsely distributed throughout maxilla. Infraorbitals poorly pigmented, with few melanophores close to orbit; infraorbitals four to six more pigmented, with large melanophores sparsely distributed. Opercle with sparse melanophores, usually more concentrated on its dorsal half; ventral third usually without dark pigmentation. Concentration of melanophores on opercle usually resembling a vertically elongated blotch, somewhat similar to the humeral blotch. Ventral portion of head pale or with a few diminute scattered melanophores on anteriormost portion. Middorsal line of body distinctly darkened. Humeral region with a conspicuous vertically elongated humeral blotch, formed by underlying and superficial melanophores; blotch over two or three scales on horizontal series immediately above lateral line, tapering ventrally and occupying one scale below lateral line. Humeral blotch bordered anteriorly and posteriorly by clearer areas. Dark broad midlateral stripe extending from the rear of clear area posterior to humeral blotch to caudal peduncle. A dark rounded blotch, with inconspicuous borders, present on caudal peduncle in most specimens; blotch when present, partially merged with the stripe. Two or three dorsalmost longitudinal scale series of flank usually with dark small chromatophores concentrated along their posterior margins, resulting in reticulate pattern; center of scales clearer, with few sparse larger melanophores; some specimens darker overall and reticulate pattern substituted by a more homogeneous dark pigmentation on scales. In some specimens with more defined reticulate pattern, the dark margins of scales are narrower along lateral line and one to three horizontal series of scales below it. Remaining scales along flank with sparse melanophores; dark lines usually present along myosepts above anal-fin base. Abdominal region clear. All fins darkened in some degree, with sparse melanophores concentrated on margins of rays; dorsal, anal, and caudal fins somewhat darker than pectoral and pelvic fins. Adipose fin with scattered small melanophores.

Color in life. Color pattern similar to the described in alcohol ( Fig. 1b ). Overall ground color yellow. Iris, infraorbitals, and opercle silvery. Humeral blotch faint or not discernible. Dark midlateral stripe more conspicuous on posterior half of body, extending to middle caudalfin rays. Unpaired fins yellowish at least on its proximal half. Pectoral and pelvic fins hyaline or poorly pigmented. Adipose fin yellowish.

Sexual dimorphism. Mature males of Astyanax varii have variable presence of hooks on fins and the examined mature females have no bony hooks on any of the fins. Some mature males possess tiny bony hooks on all fins (e.g., UFBA 4515, 29.1–34.3 mm SL), but most mature males have hooks restricted to the pectoral, pelvic, and anal fins. Anal fin of mature males with one to six hooks distributed up to the tenth first branched ray; hooks more numerous and larger on the anterior branched rays and always distally located on the posterior branch of rays. When present in the dorsal fin, up to six small hooks distributed on the first eight branched rays; hooks always distally located on the posterior branch of ray. Pectoral fins of mature males with up to six tiny hooks on the distal portion of up to the seventh branched ray. Pelvic fins with two or three small hooks on the distal portion of third to the sixth branched rays. When present in the caudal fin, very small hooks restricted to the four centralmost caudalfin rays. No other dimorphic morphological character was observed externally in the specimens examined, except by the body size. Females apparently reach larger body sizes than males (largest female observed 53.3 mm SL vs. largest male 37.9 mm SL). Males are completely mature around 29.0 mm SL and females at the same size are completely immature. The smallest mature female examined had 35.0 mm SL.

Geographical distribution. Astyanax varii is known from tributaries of rio de Contas basin, Bahia State, Brazil ( Fig. 4 ).

Ecological notes. Astyanax varii was collected in three localities of the upper and three of the lower rio de Contas basin, in altitudes ranging from 65 to 545 m a.s.l. ( Figs. 5 a–b). The stretches sampled in tributaries of the lower portion of the basin are 5-25 m wide, up to 1.8 m deep, with rocky, muddy, or sandy substrate and bordered by aquatic vegetation and trees. In that localities, A. varii was collected syntopically with 13 species: Apareiodon itapicuruensis Eigenmann & Henn , Astyanax sp., Cetopsorhamdia iheringi Schubart & Gomes , Cyphocharax pinnilepis , Geophagus brasiliensis (Quoy & Gaimard) , Hemigrammus marginatus Ellis , Hypostomus sp., Leporinus bahiensis Steindachner , Nematocharax venustus Weitzman, Menezes & Britski , Poecilia reticulata Peters , Serrapinnus piaba (Lütken) , Serrapinnus sp., and Serrasalmus brandti Lütken. In the upper rio de Contas, the species was sampled in three nearby locations in the rio Água Suja. One of them is the Balneário Rio da Barra ( Fig. 5b ), an artificial reservoir approximately 100 m long, 30 m wide, and 1.1 m deep on average, which is used mostly as a bathing place. The other sampling points in the rio Água Suja are up to 12 m wide and up to 1 m deep, with rocky and sandy-bottomed habitats, moderate water current, and with riparian vegetation mainly composed by grass and sparse trees. In those localities, A. varii was collected syntopically with 16 species: Acestrorhynchus lacustris (Lütken) , Apareiodon itapicuruensis , Astyanax aff. lacustris (Lütken) , Astyanax aff. fasciatus (Cuvier) , Characidium sp., Cyphocharax gilbert (Quoy & Gaimard) , Coptodon sp., Geophagus brasiliensis , Hemigrammus marginatus , Hypostomus sp., Leporinus sp., Megaleporinus brinco , Nematocharax varii , Parotocinclus sp., Poecilia reticulata , and Serrrasalmus brandti .

The analysis of stomach contents of two specimens of A. varii revealed the presence of allochthonous and autochthonous items, composed predominantly by filamentous algae and fragments of vascular plants and seeds, organic debris, insect aquatic larvae ( Diptera : Chironomidae and Simuliidae ) and fragments of unidentified insects.

Etymology. The specific name varii is in honor to the ichthyologist Richard P. Vari for his friendship, mentoring, and outstanding contribution to the systematic of South American freshwater fishes.

Conservation status. Astyanax varii had been collected in six localities in the upper and lower rio de Contas basin. The main locality sampled in the upper rio de Contas, the Balneário Rio da Barra, is an artificial reservoir continually exploited for tourism as a bathing place ( Barreto et al., 2018). Permanent anthropic perturbation such as loss of riparian vegetation and dams occurs in the main channel and some tributaries of rio de Contas ( Cetra et al., 2010; Sarmento- Soares et al., 2016). Despite some records of threats for the region, such as deforestation, water pollution, and erosion, there are no data about the direct effects of these threats to the populations of A. varii so far. Therefore, with the currently available data, and according to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Subcommittee, 2017), A. varii should be classified as Least Concern (LC).

Figures

Fig. 1. Astyanax varii, Brazil, Bahia State: (a) MZUSP 121062, holotype, 41.4 mm SL, Ubaitaba, lower rio de Contas basin, rio Coricó; (b) live paratype, not catalogued.

Fig. 2. Head of Astyanax varii, UFBA 8380, paratype, 40.8 mm SL, 9.3 mm HL, alizarin stained, lateral view, left side.

Fig. 3. Upper and lower jaws of Astyanax varii, UFBA 8405, paratype, 35.1 mm SL, lateral view, left side.

Fig. 4. Collection localities of Astyanax varii, rio de Contas basin, Bahia, Brazil. White dot = type locality; black dots = additional localities. Some circles indicate more than one sampling site.

Fig. 5. Collecting sites of Astyanax varii: (a) type locality, Brazil, Bahia State, Ubaitaba, Fazenda Progresso, rio Coricó, lower rio de Contas basin; (b) Brazil, Bahia State, Jussiape, Caraguataí, rio Água Suja at Balneário Rio da Barra, upper rio de Contas basin.

Tables

Tab. 1. Morphometric data for Astyanax varii, new species; n= 30, range includes holotype. SD= standard deviation.

	Holotype	Range	Mean	SD
Standard length (mm)	41.4	29.1–44.3	37.6	-
Percentages of standard length
Depth at dorsal-fin origin	31.4	28.8–33.6	31.0	1.4
Snout to dorsal fin origin	51.0	48.6–53.0	51.0	1.0
Snout to pectoral-fin origin	24.4	23.6–26.5	24.9	0.8
Snout to pelvic-fin origin	45.7	45.3–48.9	47.1	1.1
Snout to anal-fin origin	61.8	61.2–65.3	63.5	1.2
Caudal peduncle depth	10.6	10.6–12.1	11.4	0.4
Caudal peduncle length	15.9	13.7–16.9	15.0	0.7
Pectoral-fin length	20.5	19.9–22.6	21.2	0.7
Pelvic-fin length	13.0	12.9–15.1	13.9	0.6
Dorsal-fin base length	11.6	11.3–14.4	13.0	0.8
Dorsal-fin height	24.4	23.1–26.6	25.2	1.0
Anal-fin base length	23.4	23.4–27.3	25.2	1.0
Anal-fin lobe length	17.6	15.8–20.3	18.1	0.8
Eye to dorsal-fin origin	36.2	35.1–37.6	36.3	0.6
Dorsal-fin origin to caudal-fin base	52.7	50.0–54.3	52.5	1.1
Head length	24.9	23.4–26.6	24.9	0.9
Percentages of head length
Horizontal eye diameter	38.8	34.7–40.0	37.8	1.4
Snout length	23.3	19.8–23.9	22.3	1.0
Least interorbital width	29.1	28.2–32.1	30.6	1.0
Upper jaw length	40.8	40.2–43.9	42.3	1.2