Astyanax salvatoris Valdez-Moreno, Lozano-Vilano and Schmitter-Soto, 2017

Schmitter-Soto, Juan J., 2017, A revision of Astyanax (Characiformes: Characidae) in Central and North America, with the description of nine new species, Journal of Natural History (J. Nat. Hist.) 51 (21 - 24), pp. 1331-1424 : 1407-1409

Astyanax salvatoris Valdez-Moreno, Lozano-Vilano and Schmitter-Soto sp. nov.

( Figures 1 , 12 , 45 )

Astyanax sp. Williams et al. 1989.

Astyanax sp. Valdez-Moreno 1997: 58, Contreras-Balderas and Lozano-Vilano 1998: 6. Astyanax ‘Tamazulapan’, Schmitter-Soto 2016.

Diagnosis

Diagnosed from other Astyanax species in Oaxaca as follows: A. 20–22 (vs A. 21–26); total gill rakers, mean 17 (mean 22 or more in A. fi nitimus); anterior fontanel, sharp-tipped (vs blunt), long (shorter in A. fi nitimus); supraoccipital in dorsal view, short, wide-based (long, narrow-based in A. aeneus ); 4 maxillary teeth, 2 larger followed by 2 smaller (vs 1–3, all about same size); epibranchial III, distal segment straight (curved in A. fi nitimus); preopercular ventral rim, convex (straight in A. aeneus ); predorsal elements, irregularly expanded.

Description

A species of Astyanax , subgenus Astyanax (i.e. with a complete predorsal series of scales).

Head profile straight-convex at nape; snout rounded to obtusely angled; lower and upper lips even, mouth terminal. Pectoral fins not reaching posteriorly to pelvic fin origin; anal and dorsal fins do not overlap vertically. Lobes of caudal fin, subequal, or inferior longer.

D. 9; A. 20–22; pect. 12. Procurrent unsegmented dorsal rays on caudal fin, variable. Gill rakers on first arch, 18; on lower limb, 10–11. Scales in lateral line, 33–35; predorsal scales, 11–12; scale rows from lateral line to base of first dorsal-fin ray, 7–8; to base of pelvic fin, 5.5; to base of pectoral fin, 3.5–4; circumpeduncular scales, 15–17. A short, single scale row on anal fin base. Nuptial tubercles, not seen. Total vertebrae 32–33, 18–19 caudal. Detailed frequencies are given in Table 3.

Largest examined specimen, 61.0 mm SL. Typically, body depth 33% SL, head length 28% SL, orbital diameter 30% HL, and interorbital distance 8.2% SL (further morphometric data are given in Table 4).

Anterior fontanel long, straight-sided, sharp-tipped. Supraoccipital process in dorsal view, short, wide-based; caudally strongly concave in lateral view. Vomer rostrally slightly concave. Dentigerous arm of premaxilla, much longer; 0–4 teeth. Highest tooth on dentary, first or third; posterior teeth, abruptly smaller. Dorsal edge of articular, convex. Maxillary, with a straight-concave anteroinferior edge; 4 teeth, 2 larger. Quadrate, dorsal process expanded. Metapterygoid, rostral arm longer than ventral, only 1 dorsorostral projection. Infraorbital II, a triangle with a long convex base; infraorbital III, inferoposteriorly semicircular; infraorbital IV, square with a projection; a narrow contact between infraorbitals II and III. Urohyal rostral end blunt, with a subterminal projection dorsad, its ventrorostral edge convex, its ventral apex almost at caudal end; ceratohyal foramen oval, its rostral vertices angled, its ventral side undulate. Epibranchial III, insertion of uncinate process round, the distal segment of the main body straight. Upper pharyngeal bones, oval; lower pharyngeal teeth plate, single, its caudal side concave. Dorsal side of hyomandibular, convex. Opercular dorsal edge, obtuse; sides of dorsal half, parallel; posterior edge, dorsally concave, ventrally straight-convex; ventral tip, rounded. Interopercle, posterior edge, straight-convex, with a spine. Preopercle, anterodorsal edge, with a median convexity; ventral rim, convex; posteroventral edge, angled; 2 divergent canals at angle. Six predorsal bony elements, irregularly expanded; rostral edge of first pterygiophore angled. Coracoid with 6 interdigitations in suture to cleithrum, a straight caudal edge, a single posteroinferior spine. Caudad process of postcleithrum, digitiform. Proximal edge of pelvic bone, convex. Dorsal and caudal tips of scaphium, truncate; dorsoposterior edge, undulate. Neural spines under dorsal fin, bent-tipped. Seventh caudal vertebra from tail, with a haemal spine displaced caudad. Rostral edge of largest hypuric plate, concave. Epuric plate on last neural spine, convexedged.

Humeral spot, squarish. Pigment on anal fin, very sparse, uniform. Caudal spot, both on peduncle and on fin rays.

Type material and depositor

Holotype UANL 22296 , 60.8 mm SL, ‘ojo de agua’ (spring) of Tamazulapan, uppermost eastern Balsas drainage, Oaxaca, Mexico, coll. S. Contreras-Balderas and A. Contreras- Arquieta, August 1992 ( Figure 46 ) . Paratypes: TNHC 25027 (2 specimens), TU 185676 (2), UANL 14327 (13), UMMZ 234194 (2), USNM 357728 (2), same collection data as holotype; UANL 14306 (109), same locality, coll . G . Aguilar, April 1983.

Etymology

Named to honour the late Dr Salvador Contreras-Balderas, one of the greatest students of Mexican fishes in general, and of Astyanax in particular. An adjective.

Distribution

Endemic to springs at Tamazulapan, Oaxaca, Balsas drainage, Pacific versant of Mexico ( Figure 12 ).

Proposed common names

Tamazulapan tetra, sardinita del Tamazulapan.

Remarks

The species is part of clade Ib of Ornelas-García et al. (2008). It was listed as of Special Concern by Williams et al. (1989), but not by Jelks et al. (2008).

The authorship of this species is joint with M.E. Valdez-Moreno and M.L. Lozano- Vilano, who independently recognised it as distinct.

Figures

Figure 1. A premaxilla with four premaxillary teeth in the inner row, two rows (Astyanax salvatoris sp. nov., UMMZ 234194).

Figure 12. Map of Mexico, showing distribution localities of Astyanax acatlanensis sp. nov., A. argentatus, A. mexicanus, A. rioverde sp. nov., A. salvatoris sp. nov., A. tamiahua sp. nov. and A. tehuacanensis sp. nov. A larger symbol denotes the type locality (ambiguous for A. mexicanus; see text).

Figure 45. Astyanax salvatoris sp. nov., holotype, UANL 22296.

Figure 46. Astyanax tamiahua sp. nov., holotype, UMMZ 250294.