Astyanax pirabitira, De Lucena, Carlos A. S., Bertaco, Vinicius A. & Berbigier, Guilherme, 2013

De Lucena, Carlos A. S., Bertaco, Vinicius A. & Berbigier, Guilherme, 2013, A new species of Astyanax from headwater streams of southern Brazil (Characiformes: Characidae), Zootaxa 3700 (2), pp. 226-236 : 227-230

Astyanax pirabitira , new species

( Figs. 1–2 , Table 1 )

Astyanax sp.n. 1.—Malabarba et al. 2009: 137 (listed and distribution). Astyanax sp.3.—Becker et al. 2013 (listed and distribution).

Holotype. MCP 47707, 65.5 mm SL, Brazil, Rio Grande do Sul, border between Cambará do Sul and Bom Jesus, rio das Antas, rio Jacuí drainage, laguna dos Patos system, ca. 28º50’S 50º06’W, 14 Jan 1989, C.A.S. Lucena, E.H.L. Pereira & P.V. Azevedo.

Paratypes. Brazil, Rio Grande do Sul State, rio Jacuí drainage, laguna dos Patos system. MCN 19725, 12, 37.8–57.1 mm SL, MCP 14390, 256 (12, 57.0– 70.5 mm SL; 7 c&s 50.8–65.0 mm SL), collected with the holotype. MCP 22796, (3, 34.7–42.0 mm SL), rio das Antas, São José dos Ausentes, ca. 28º47’S 49º59’W, 4 Apr 1999, V.A. Bertaco, R.E. Reis & E.H. Pereira. MCP 25654, 37 (4, 30.0– 69.5 mm SL), rio das Antas upstream of camping Vale das Trutas, São José dos Ausentes, ca. 28º47’S 49º59’W, 24 Mar 2000, W. Bruschi Jr. MCP 25655, 5 (2, 45.8–46.5 mm SL), rio das Antas below of camping Vale das Trutas, São José dos Ausentes, ca. 28º47’S 49º59’W, 23 Mar 2000, W. Bruschi Jr. MCP 26768, 37, 19.8–90.9 mm SL, arroio Ribeirão, tributary of rio Tainhas, São Francisco de Paula, 29º12’00”S 50º21’00”W, 19 Dec 2000, W. Bruschi Jr. & L. Daros. UFRGS 4860, 57 (12, 56.2–83.6 mm SL), stream tributary of the rio das Antas, São José dos Ausentes, 28º48’36”S 49º59’36”W, 6 Jan 2000, L.R. Malabarba, A.R. Cardoso, A. Schwarzbold & L.T.W. Sozinski. UFRGS 4861, 194 (21, 65.0–82.0 mm SL; 5 c&s, 59.9–81.0 mm SL) rio das Antas, São José dos Ausentes, ca. 28º47’S 49º59’W, 7 Jan 2000, L.R. Malabarba, A.R. Cardoso, A. Schwarzbold & L.T.W. Sozinski. UFRGS 4883, 19 (12, 54.1–77.2 mm SL), stream tributary of rio das Antas, São José dos Ausentes, 28º49’11”S 49º59’40”W, 6 Apr 2000, Ictiologia UFRGS.

Non-types. Brazil, Rio Grande do Sul State, rio Jacuí drainage, laguna dos Patos system. MCP 28299, 1, 45.2 mm SL, arroio Contendas, Tainhas, São Francisco de Paula, ca. 29º16’S 50º18’W, 23 Sep 1997, W. Bruschi Jr. & G. Vinciprova. UFRGS 4899, 3, 43.1–59.2 mm SL, rio das Antas, São José dos Ausentes, ca. 28º49’42”S 50º42’00”W, 6 Apr 2000, Ictiologia UFRGS. UFRGS 6154, 19, 29.1–33.3 mm SL, rio das Antas, São José dos Ausentes, 28º49’42”S 50º42’00”W, 25 Nov 2000, L. Bastos, P. Colombo, D. Gelain & T. Hasper. Rio Uruguay basin. MCP 11522, 2, 28.1–42.0 mm SL, arroio Cachoeirinha tributary of rio Quatis on road between Vacaria and Bom Jesus, upper rio Pelotas basin, ca. 28º39’S 50º36’W, 4 May 1995, C.A.S. Lucena, L.R. Malabarba & R.E. Reis.

Diagnosis. Astyanax pirabitira belongs to the A. scabripinnis species complex and is distinguished from the members of this group by the presence of two humeral spots (vs. one spot in A. courensis Bertaco, Carvalho & Jerep, A. epiagos Zanata & Carmelier, A. gymnogenys Eigenmann, A. intermedius Eigenmann, A. ita Almirón, Azpelicueta & Casciotta, A. jacobinae Zanata & Carmelier, A. jenynsii (Steindachner) , A. jordanensis Alcaraz, Pavanelli & Bertaco, A. laticeps (Cope), A. microschemos Bertaco & Lucena, A. paranae Eigenmann, A. rivularis (Luetken) , A. serratus Garavello & Sampaio, A. totae Haluch & Abilhoa, and A. varzeae Abilhoa & Duboc ); anterior humeral spot vertically elongate (vs. horizontally elongate in A. laticeps , A. serratus , and A. troya Azpelicueta, Casciotta & Almirón ); narrow interorbital width 22.2–28.7% HL, mean=25.0% (vs. 28.8–33.0%, mean=31.6%, in A. burgerai Zanata & Carmelier , 27.8–34.7%, mean=32.8%, in A. goyanensis Miranda-Ribeiro , 35.2–37.8% in A. gymnogenys , 32.3–47.1% in A. intermedius Eigenmann , 33.2–33.5% in A. jenynsii , 30.6–40.3% in A. jordanensis , 27.3–30.4%, mean=28.8%, in A. leonidas , 31.0–35.6% in A. ojiara Azpelicueta & Garcia , 31.7– 39.2% in A. pirapuan Tagliacollo, Britzke, Silva & Benine , 35.0–43.9% in A. serratus , 29.7–33.3% in A. troya , 29.8–35.7% in A. varzeae , 40.7% in A. scabripinnis ); 37–40, mode=38 lateral line scales (vs. 31–34 in A. burgerai , 34–35 in A. jenynsii , 35–36 in A. courensis , 35–37, mean=36.0, in A. goyanensis and A. pirapuan , 34–36 in A. ita , A. paris Azpelicueta, Almirón & Casciotta and A. turmalinensis Triques, Voino & Caiafa ); one or two teeth in the maxilla (vs. three teeth in A. jacobinae , three or four in A. paris and two to five, usually three, in A. totae ); second to fourth tooth of the inner premaxillary series with seven cusps (vs. three to five cusps in A. cremnobates Bertaco & Malabarba, A. brachypterygium Bertaco & Malabarba, and A. pirapuan ); maxilla short, reaching or slightly surpassing the anterior margin of the pupil, upper jaw length 38.1–44.6% HL (vs. maxilla long reaching the vertical through the middle of the pupil, 45.3–48.1% in A. paranae ); body scales with chromatophores distributed throughout the surface of the scales (vs. body scales with concentration of chromatophores on their posterior margin and clear central region, resulting in a reticular color pattern in A. turmalinensis and A. rivularis ); lower caudal peduncle depth 10.3–12.5%, mean=11.5%, SL (vs. 12.2–15.3%, mean=13.6%, in A. brachypterygium ); base of anteriormost anal-fin rays covered by a single series of 5–12 scales (vs. scales series absent in A. epiagos ); 15– 20 branched anal-fin rays (vs. 20–23 in A. ojiara and 21 in A. scabripinnis ); total gill-rakers on the first arch 20–22 (vs. 17–19 in A. leonidas and 16 in A. microschemos ); and lower head depth, 84.5–97.0% HL (vs. 100.4–119.9% in A. obscurus (Hensel)) . Astyanax pirabitira can be also distinguished from A. obscurus by the lower body depth 27.1–34.0% SL, mean=31.2%, n=70 (vs. 32.5–37.9%, mean=35.4%, n=31) and by the ventral portion of the first humeral spot slightly narrower than the upper portion (vs. lower portion very narrow, with a conspicuous constriction at the junction with the upper portion). Furthermore it differs by the absence of bony hooks in the fins of males (vs. presence of bony hooks in A. brachypterygium , A. burgerai , A. cremnobates , A. epiagos , A. jordanensis , A. leonidas , A. ojiara , A. paranae , A. pirapuan , A. scabripinnis , A. serratus , A. totae and A. troya ). A new species of the A. scabripinnis complex is being described from the upper rio Iguaçu (Ingenito & Duboc, in press). This species differs from A. pirabitira by its subterminal mouth on specimens larger than 48.2 mm SL (vs. terminal mouth), by the presence of one humeral spot (vs. two humeral spots), and by the presence of four to five cusps on the second to fourth tooth in the inner premaxillary series (vs. seven cusps). Astyanax pirabitira differs from A. guaricana Oliveira, Abilhoa & Pavanelli by 37–40, mode=38 lateral line scales (vs. 40-43 mode = 42), interorbital distance, 22.2-28.7% (vs. 32.7-40.9% HL) and by the absence of bony hooks in the anal fin of males (vs. presence).

Description. Morphometric data summarized in Table 1 . Body compressed and elongate, with greatest body depth in around middle of pectoral fins. Dorsal profile of head straight or slightly concave from region above eye to supraoccipital spine. Dorsal body profile convex from tip of supraoccipital spine to base of last dorsal-fin ray; straight from that point to adipose fin origin. Ventral profile of body convex from mandibular symphysis to pelvic fin origin, nearly straight to anal-fin origin, and posterodorsally slanted along anal-fin base. Caudal peduncle deep, nearly straight on dorsal and ventral margins.

Snout rounded from margin of upper lip to vertical through anterior nostrils. Head somewhat pointed anteriorly in lateral profile. Mouth terminal, jaw isognathous. Maxilla extending posteriorly to vertical through anterior margin of orbit reaching pupil. Maxilla widened anteroposteriorly.

Two tooth rows in premaxilla; outer row with 4(1), 5(39), or 6(1)* pentacuspid (rarely tricuspid) teeth, central cusp longer; inner row with five teeth, gradually decreasing in length from first to fifth; usually with four cusps on first tooth, seven cusps on second to fourth teeth and five or six cusps on fifth tooth; central cusp twice as long and broad as other cusps. Maxilla with one or two teeth bearing three to five cusps; central cusp slightly broader than others. Five or six anteriormost dentary teeth decreasing gradually, all pentacuspid, remaining four to six teeth smaller, uni- to tretracuspid ( Fig. 2 ).

Dorsal-fin rays i,9(5)* or 10(62); first unbranched ray approximately half length of second ray. Distal margin of dorsal fin nearly straight to slightly convex. Dorsal fin origin slightly behind middle of SL. Origin of adipose fin at vertical through second or third last anal-fin rays. Anal-fin rays iv(6 c&s) or v(5 c&s), 15(2), 16(8), 17(16)*, 18(25), 19(14) or 20(2). Anal fin profile smoothly concave. Anal fin origin posterior to vertical through base of last dorsal-fin ray. Pectoral-fin rays i,11(2), 12(6), 13(26)*, 14(29), or 15(4). Pectoral-fin tip not reaching pelvic-fin insertion. Pelvic-fin rays i,6(5)* or 7(62). Pelvic fin origin slightly anterior to vertical through dorsal-fin origin. Pelvic-fin tip does not reach or barely reaches anal-fin origin. Caudal fin forked, lobes similar in size, i+17+i(67) principal rays, no scales in the lobes. Dorsal procurrent rays 11(7), 12(3) or 13(1) and ventral procurrent rays 9(3), 10(6) or 11(2).

Lateral line complete with 37(5)*, 38(30), 39(27), or 40(5) scales. Scale rows between dorsal-fin origin and lateral line 6(64)* or 7(3); scale rows between lateral line and pelvic-fin origin 4(26)* or 5(41). Predorsal scales 11(2)*, 12(26), 13(29) or 14(4) arranged in regular series. Scale rows around caudal peduncle 14(24)*, 15(9), or 16(34). Scale sheath along anal fin base 5-12 scales (59), in single series, covering base of anteriormost rays.

Precaudal vertebrae 18(8) or 19(3); caudal vertebrae 17(1), 18(1), 19(8) or 20(1); total vertebrae 35(1), 37(7) or 38(3). Supraneurals 5(2), 6(7) or 7(2). Gill-rakers upper branch 6(2), 7(19), or 8(30); lower branch 12 (7), 13(35)* or 14(5); total number 20(22)*, 21(12) or 22(5).

Color in alcohol. Dorsal and dorsolateral portions of head and body dark brown. Body with black, narrow longitudinal stripe slightly oblique, originating at the junction of first and second scale rows immediately above lateral line, and extending from vertical through half of dorsal fin, or slightly behind this point to caudal fin base; stripe slightly expanded dorsally and ventrally on caudal peduncle, forming small caudal spot. Black longitudinal stripe in adult specimens wide large from posterior region of humeral spot to caudal peduncle, expanding as a caudal spot; dark pigmentation present over middle caudal-fin rays. Two humeral spots; anterior one, conspicuous, vertically elongate, with upper portion wider than lower portion; lower portion in some adult specimens very narrow. Second humeral spot large, fainter than first humeral blotch, not surpassing lateral line ventrally. Fins with few scattered dark chromatophores ( Fig. 1 ).

Sexual dimorphism. Secondary sexual characters were not found on examined specimens. Gill glands (Burns & Weitzman, 1996) were not found macroscopically on the first gill arch.

Distribution. Astyanax pirabitira is known from the upper rio das Antas drainage, laguna dos Patos system, and upper rio Pelotas basin, rio Uruguay drainage, southern Brazil ( Fig. 3 ).

Etymology. The specific name pirabitira , from Tupi-Guarani, means mountain fish (pira, meaning fish, and ybytyra meaning mountain). It is a reference to the occurrence of the species in altitudes higher than 800 m.

Ecological notes. Astyanax pirabitira lives in streams and rivers, inhabiting lotic shallow areas (up to 1 m deep) with clear water and bottom composed of gravel and stones, at altitudes from 800 to 1200 m above sea level. Only eight species occur syntopically with A. pirabitira : Astyanax brachypterygium , Australoheros sp., Cnesterodon brevirostratus , Eurycheilichthys sp., Jenynsia eirmostigma , Pareiorhaphis hystrix , Rhamdia sp., and Trichomycterus tropeiro .

Figures

FIGURE 1. Astyanax pirabitira, MCP 47707, 53.9 mm SL, holotype, rio das Antas, border between Cambará do Sul and Bom Jesus, Rio Grande do Sul, Brazil. Scale bar = 1 cm.

FIGURE 2. Astyanax pirabitira, UFRGS 4861, 81.0 mm SL, paratype. Upper and lower jaw teeth, right side, medial view. Scale bars = 1 cm.

FIGURE 3. Map of southern Brazil and Uruguay, showing the distribution of the examined material of Astyanax pirabitira. A = rio das Antas, laguna dos Patos system, and P = rio Pelotas, rio Uruguay basin. Some symbols represent more than one lot or locality. Red circle = type locality.

Tables

TABLE 1. Morphometric data for holotype and paratypes of Astyanax pirabitira, n. sp., n = 70 (holotype not included) from the upper rio das Antas drainage, laguna dos Patos system, Rio Grande do Sul, Brazil. SD = Standard deviation; SL = Standard length.

	Holotype	Paratypes	Mean	SD
Standard length (mm)	65.5	30.0–86.3	65.1	-
Percents of SL
Predorsal distance	55.2	51.6–57.7	54.5	1.1
Prepelvic distance	52.5	48.8–54.2	51.6	1.2
Prepectoral distance	27.7	25.1–30.8	27.6	1.2
Preanal distance	68.2	64.5–70.1	67.4	1.9
Depth at dorsal-fin origin	33.5	27.1–34.0	31.2	1.5
Caudal peduncle depth	11.3	10.3–12.5	11.5	0.4
Caudal peduncle length	14.6	13.3–16.5	14.9	0.8
Anal-fin base length	21.9	18.9–24.8	22.3	1.1
Dorsal-fin length	23.8	21.3–27.3	24.1	1.1
Pelvic-fin length	15.2	13.3–16.4	14.7	0.6
Pectoral-fin length	22.4	18.6–23.4	20.9	1.0
Head length	30.6	26.1–31.4	28.5	1.4
Percents of Head length
Snout length	26.3	24.0–28.3	26.1	0.8
Head depth	87.5	84.5–97.0	89.6	1.8
Upper jaw length	40.3	38.1–44.6	41.5	1.3
Orbital diameter	27.8	27.0–35.0	30.6	1.8
Interorbital width	23.8	22.2–28.7	25.0	1.3