Astyanax puka, Mirande, Juan Marcos, Aguilera, Gast Ỏ N & Azpelicueta, Mar A De Las Mercedes, 2007

Mirande, Juan Marcos, Aguilera, Gast Ỏ N & Azpelicueta, Mar A De Las Mercedes, 2007, A new species of Astyanax (Characiformes: Characidae) from the endorheic R o Sal basin, Tucumán, northwestern Argentina, Zootaxa 1646, pp. 31-39 : 33-37

Astyanax puka , new species

( Figs. 1–3 , Table 1 )

Holotype. CI-FML 3844 male, 50.3 mm SL, Argentina, Tucum<n, Monteros, Río Salí basin, Río Mandolo, under the bridge of Ruta Provincial 344, near Monteros City, coll. M. Mirande and G. Aguilera. July 2005. Paratypes: CI-FML 3849, 19 ex., 44.8–59.5 mm SL, collected with the holotype. CI-FML 3851, 2 ex., 53.4– 60.1 mm SL, Argentina, Tucum<n, Trancas, Río Salí basin, Río Salí at Balneario El Boyero, coll. G. Aguilera. August 2006.

Additional material (not designated as paratypes): CI-FML 3850, 3 ex. (C&S), 42.7–50.0 mm SL, collected with the holotype.

Diagnosis: Astyanax puka is distinguished from the remaining species of the genus by the following combination of characters: shallow body (33.5–39.8 % SL), 36–38 perforated scales in lateral line, 6/5 transverse scales, 9–10 gradually decreasing dentary teeth, distally expanded premaxillary teeth, one distally expanded maxillary tooth with 7–9 cusps, short upper-jaw length (34.5–37.8 % HL), short maxilla (20.7–23.3 % HL) expanded abruptly under maxillary tooth position, short postorbital distance (36.6–46.9 % HL), short pelvic to anal-fin origin distance (17.1–20.6 % SL), 22–27 branched anal-fin rays, long caudal peduncle (13.3–16.5 % SL), bony hooks restricted to pelvic-fin rays 2 to 6 and anterior 6–13 branched anal-fin rays on mature males, and the presence of broad denticles on anterior, lateral, and posterior edges of first ceratobranchial gill rakers. A detailed comparison of Astyanax puka with the other species of Astyanax appears in the “Discussion” section below in this paper.

Description: Morphometrics of the holotype, and 19 paratypes are presented in Table 1 . Body rather slen- der (33.5–39.8 % SL), with maximum depth at dorsal-fin origin. Dorsal profile slightly convex over snout and straight from interorbital area to tip of supraoccipital process; slightly convex to dorsal-fin origin; straight from this point to caudal peduncle; gently concave along caudal peduncle to base of caudal-fin rays. Ventral profile of body convex from lower-jaw tip to anal-fin origin; straight to anal-fin origin; slanted dorsally to end of anal fin, and almost straight under caudal peduncle. Ventral portion of body between bases of pectoral and pelvic fins transversally rounded; ventral portion of body between origins of pelvic and anal fins more compressed laterally.

Dorsal-fin origin equidistant from snout tip and caudal-fin origin. Pelvic-fin origin located slightly anterior to vertical through dorsal-fin origin. Anal-fin origin located just behind vertical line through base of posteriormost dorsal-fin rays. Tip of pectoral fin reaching pelvic-fin origin, and tip of pelvic fin reaching anal-fin origin in males and some females.

Mouth terminal, placed at level of inferior third of eye. Premaxilla bearing two series of teeth; ascending process with rather broad base and acute tip, less developed than alveolar ramus. Outer row with 2(2), 3(18*), or 4(2) pentacuspidate teeth, with slender base and slightly expanded distally; inner row with 5 distally expanded teeth, slightly concave anteriorly; symphysial tooth slender with 5 cusps, second to fourth teeth with 7–9 cusps and fifth tooth with 5–6 cusps ( Fig. 2 ). Ascending process of maxilla broad, expanded over distal part of premaxillary alveolar ramus; laminar process of maxilla short, with 1(22*) tooth with 7–9 cusps, abruptly expanded under maxillary tooth position; ligamentum primordiale attached over horizontal line through maxillary tooth base ( Fig. 2 ). Dentary moderately deep (aproximately 45 % of its length), with its maximum depth approximately in middle of its length; dentary with 9–10 gradually decreasing teeth, first 4 or 5 heptacuspidate, sixth and seventh penta or tricuspidate, and posterior ones tricuspidate or conical ( Fig. 2 ).

Eye moderately large, longer than snout. Third infraorbital not contacting latero-sensory canal of preopercle either ventrally or posteriorly.

Dorsal fin with iii, 9 rays; distal margin of dorsal fin straight, with last unbranched and first branched dorsal fin rays longest. First unbranched dorsal-fin ray mostly visible in cleared and stained specimens. Anal fin with iv-v, 22(1), 23(2), 24(7), 25(8*), 26(2), or 27(2) rays; small lobe formed by last unbranched and first 5–6 rays in both sexes, pointed in females and rounded in males. Males with hooks on distal half of last unbranched anal-fin ray and posterior branch of first 6–13 branched anal-fin rays; usually one pair of hooks per segment. Caudal fin with principal rays i,17,i. Pectoral fin with i,11–12 rays. Pelvic fin with i,7 rays; males bearing hooks on posterior branch of pelvic-fin rays 2 to 7, one pair of hooks per segment.

Scales cycloid, without circuli on posterior field. Lateral series with 36(3), 37(18*), or 38(1) perforated scales. Scales between dorsal-fin origin and lateral line 6(20*) or 7(2); scales between lateral line and pelvicfin origin 5(22*). Scales around caudal peduncle 13(1), 14(15*), 15(4), or 16(2). Scales between tip of supraoccipital spine and base of dorsal fin 10–11, usually forming a regular row. One row of scales forming a sheath-covering base of unbranched and first 7–12 branched anal-fin rays. Few scales covering only the base of caudal-fin lobes.

First branchial arch with 17–18 gill rakers: 6 on epibranchial, 1 on cartilage, 8–9 on ceratobranchial, and 2 on hypobranchial; posterior edge of first epibranchial with a second row of 4–5 gill rakers. Gill rakers on first ceratobranchial with broad denticles on anterior, lateral, and posterior edges ( Fig. 3 ). Thirty-five to 36 vertebrae (15–16 precaudal and 19–20 caudal vertebrae). Four or five supraneurals, 11 pairs of ribs. Caudal fin with 10 dorsal and 8–9 ventral procurrent rays.

Colour in life: Body silvery, darker dorsally. Lateral silvery band inconspicuous. First humeral spot vertically elongated, narrow, and second one faint. Intensely red anal and caudal fins. Hyaline pectoral, pelvic and dorsal fins.

Colour in alcohol: Body yellowish, darker dorsally. Head dark dorsally, with chromatophores scattered on maxilla and anterior part of lower jaw; few chromatophores on first to third infraorbital. First humeral spot broad, vertically elongated and intensely pigmented, extended from second row of scales over lateral line to second row under lateral line. Second humeral spot rather well defined, especially over lateral line. Well defined, but rather thin, lateral stripe extended from postero-dorsal angle of opercle, through the humeral spots to end of middle caudal-fin rays; the lateral stripe is sligthly expanded vertically at caudal peduncle, although not forming a conspicuous spot. Dense chromatophores located under proximal and medial surface of scales of dorsum, leaving distal area lighter, forming thus a reticulate pattern. Scales of flanks with a thin line of melanophores in its distal border. Pectoral and pelvic fins hyaline. Dorsal, anal, and caudal fins hyaline, with chromatophores scattered on membrane, more densely concentrated distally, especially evident in membranes of caudal fin.

Distribution: Astyanax puka is known only from the Mandolo and Salί rivers, Rίo Salί endorheic basin, Tucumán, northwestern Argentina (Fig. 4).

Habitat notes: The type locality is approximately one-meter deep and has a gravel bottom, with slow current.

Etymology. The specific epithet puka is a Quichua word that means red, in allusion to the intensely red anal and caudal fins of this species. A noun in apposition.

FIGURE 4. Geographical distribution of Astyanax puka , Rίo Salί basin, Tucumán, northwestern Argentina. Type locality is indicated by an open dot.

Figures

FIGURE 1. Astyanax puka; above: CI-FML 3844, male, holotype, 50.3 mm SL; below: CI-FML 3849, female paratype, 59.0 mm SL. Scale bar = 10 mm.

FIGURE 2. Astyanax puka, CI-FML 3850, 44.2 mm SL: right premaxilla, maxilla and lower jaw in medial view. Scale bar = 1 mm.

FIGURE 3. Detail of morphology of first ceratobranchial gill-rakers; left: Astyanax mexicanus, ANSP 162587, 48.5 mm SL; right: Astyanax puka, CI-FML 3850, 44.2 mm SL. Scale bar = 0.2 mm.

Tables

TABLE 1. Astyanax puka. Morphometrics of holotype and 21 paratypes. Minimum, maximum, and mean ± standard deviation in parentheses. Standard length is expressed in mm. Holotype is also included in “ Males ” column.

	Holotype Females (n=11)	Males (n=11)
Standard length	50.3 49.0–59.5	44.8–60.1
% of standard length
Predorsal distance	50.3 49.3–53.8 (50.8±1.4)	49.4–51.8 (50.2±0.8)
Preanal distance	63.3 62.8–65.2 (64.2±0.8)	62.0–64.6 (63.1±0.8)
Preventral distance	47.5 46.3–50.0 (47.6±1.1)	46.1–47.5 (46.6±0.4)
Body depth	35.1 34.7–39.2 (36.7±1.5)	33.5–39.8 (35.8±1.7)
Dorsal-fin base	12.6 12.4–14.2 (13.3±0.5)	12.6–15.3 (13.7±0.8)
Anal-fin base	29.2 26.8–31.7 (29.0±1.3)	28.8–32.3 (30.5±1.2)
Pectoral-fin length	22.7 20.9–23.2 (22.1±0.8)	22.1–24.2 (23.1±0.7)
Pelvic-fin length	19.0 16.5–18.7 (17.5±0.6)	18.0–19.8 (18.6±0.5)
Pectoral to pelvic-fin distance	22.7 21.2–24.2 (22.7±1.0)	20.2–22.7 (21.7±0.7)
Pelvic to anal-fin distance	17.4 17.4–20.6 (18.3±0.9)	17.1–19.4 (17.9±0.7)
Head length	26.0 25.7–27.8 (26.6±0.7)	25.6–28.6 (26.4±0.8)
Peduncle depth	11.5 10.9–12.2 (11.6±0.4)	10.5–12.9 (11.6±0.6)
Peduncle length	14.8 13.3–15.9 (14.6±0.7)	13.4–16.5 (14.9±1.1)
% head length
Eye diameter	39.4 35.8–40.4 (38.6±1.5)	37.5–40.6 (39.2±1.1)
Interorbital width	33.2 30.5–34.8 (32.3±1.3)	30.0–33.9 (31.9±1.2)
Postorbital distance	41.7 36.6–46.9 (42.4±2.5)	38.0–45.5 (41.1±2.0)
Snout length	25.4 22.8–25.9 (24.4±1.1)	22.6–26.0 (24.5±0.9)
Maxillary length	20.8 20.7–23.1 (22.2±0.7)	20.7–23.3 (21.9±0.9)
Upper-jaw length	34.8 34.7–37.4 (36.2±0.9)	34.5–37.8 (36.0±1.0)