Astyanax caballeroi ( Contreras-Balderas and Rivera-Teillery 1985 ) 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 : 1376-1379

Astyanax caballeroi ( Contreras-Balderas and Rivera-Teillery 1985) comb. nov.

( Figures 15 , 31 ; see original description for illustration of holotype)

Bramocharax (Catemaco) caballeroi Contreras-Balderas and Rivera-Teillery 1985: 10 . Diagnosis

Diagnosed from other Astyanax species in Veracruz as follows: gill rakers on lower arm of first arch, 12 or more (usually fewer in A. fi nitimus); body slender, 32% SL or less (32% or more in A. fi nitimus and A. tamiahua sp. nov.); longest dorsal-fin ray, mean 24.7% SL (mean 23.6% in A. fi nitimus); pectoral length, mean 22.3% SL (mean 20.5% in A. fi nitimus); longest anal-fin ray, mean 16.1% SL (mean 13.6% in A. fi nitimus); least depth, 11% SL or less (11% or more in A. fi nitimus and A. tamiahua sp. nov.); anterior fontanel, longer (vs shorter); supraoccipital, caudal end in lateral view, concave (angled in A. fi nitimus); infraorbital II, with an angled base (base convex in A. aeneus ).

Redescription

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

Head profile straight to convex; snout elongated in adults, although less so than in other species previously assigned to Bramocharax ; lips even; mouth terminal. Pectoral fins always reach pelvic fin origin; anal and dorsal fins may overlap. Lobes of caudal fin, subequal.

D. 10, rarely 9; A. 24–29, mean 25; pect. 11–16. Procurrent unsegmented dorsal rays on caudal fin, 9 or fewer. Gill rakers on first arch, 20–25, mean 22 (to 29, including rudiments, as the original descriptors did: see Contreras-Balderas and Rivera-Teillery 1985, their fig. 5); on lower limb, 10–14, modally 11 (to 15). Scales on lateral line, 33–37, mean 35; predorsal scales, modally 12, up to 14; scale rows from lateral line to base of first dorsal-fin ray, 7; to base of pelvic fin, 6; to base of pectoral fin, 3.5–4; circumpeduncular scales, 14–15. A single, short row of scales on anal-fin base. Nuptial tubercles, simple. Total vertebrae 34, modally 20 caudal. Detailed frequencies are given in Table 3.

Largest examined specimen, 59.8 mm SL. Body depth, 27–32% SL. Head length, 24–27% SL; eye rather large, 31–36% HL; interorbital distance, narrow, 6.1–9.8% SL, mean 8.7% SL (further morphometric data appear in Table 4). The Bramocharax -like elongation of the snout occurs only in some of the larger individuals, and the morphological differentiation between morphs does not correspond to any molecular divergence ( Ornelas-García et al. 2014).

Anterior fontanel, long. Supraoccipital process in dorsal view, long, narrow-based, concave in lateral view. Vomer rostrally slightly concave. Arms of premaxilla, subequal; 4 teeth. Highest tooth on dentary, first or third; posterior teeth, abruptly smaller. Dorsal edge of longer articular arm, straight; tip, pointed. Maxillary, with a convex anteroinferior edge; 1–3 teeth. Quadrate dorsal process, not expanded. Metapterygoid, rostral arm longer than ventral, 2 dorsorostral projections. Infraorbital II, triangular with an angled base; infraorbital III, inferoposteriorly semicircular; infraorbital IV, square, with a projection; contact between infraorbitals II and III, wide. Urohyal rostral end turned up, pointed; its ventrorostral edge convex, its ventral apex closer to caudal end; ceratohyal foramen oval; rostral vertices of ceratohyal angled, the ventral side convex. Epibranchial III, insertion of uncinate process angled, the distal segment of the main body straight. Upper pharyngeal bones, oval; lower pharyngeal plate single, its caudal side concave. Dorsal side of hyomandibular, convex. Opercle, dorsal edge concave-convex; sides of dorsal half, parallel; posterior edge, dorsally concave, ventrally straight-convex; ventral tip, rounded. Interopercle, posterior edge, straight-convex, with a spine; preopercular anterodorsal edge, straight-concave; ventral rim, straight; posteroventral edge, curved; 2 parallel canals at angle. Five to 6 predorsal bony elements, not expanded; rostral edge of first pterygiophore, angled. Coracoid with a single, widely triangular interdigitation in suture to cleithrum, a concave caudal edge, a single posteroinferior spine. Caudad process of postcleithrum, digitiform. Proximal edge of pelvic bone, convex. Postanal element, short. Scaphium dorsal tip truncate, caudal tip sharp, dorsoposterior edge slightly concave. Neural spines under dorsal fin, bent at tips. Seventh caudal vertebra from tail, with a haemal spine displaced caudad. Largest hypuric plate, with straight borders. Epuric plate on last neural spine, distally spiny.

Humeral spot, P-shaped. Pigment on anal fin, sparse, concentrated medially. Caudal spot, both on peduncle and on fin rays.The live colour of this species is ‘almost identical’ to the other Astyanax of Mexico ( Contreras-Balderas and Rivera-Teillery 1985, p. 14); however, all fins can display an unusual suffusion of yellow ( Figure 31 ).

Type material and depositor

Holotype UANL 5681, 115.1 mm SL, north-western beaches of Lake Catemaco , Veracruz, Mexico, coll. R. Rivera Teillery, December 1975 . Paratypes: UANL 2368 (22 specimens), 2459 (1), 2864 (3), UANL 2949 (39), same collection data as holotype; AMNH 55679 (4); BMNH (3); ENCB 3966 (3); IBUNAM (3); TU (3), UANL 2462 (142), UMML 200245 (4); USNM 325997 (2); S . Contreras-Balderas, November 1976, commercial catch.

Distribution

Endemic to Lake Catemaco , Veracruz ( Figure 15 ) .

Remarks

The species is a part of lineage Ib of Ornelas-García et al. (2008), the same sublineage as A. fi nitimus. See also the study by Ornelas-García et al. (2014) on the morphological and genetical variation of A. caballeroi .

Figures

Figure 15. Map of northern Central America and southern Mexico, showing distribution localities of Astyanax aeneus, A. altior, A. angustifrons, A. bacalarensis sp. nov., A. caballeroi, A. finitimus, A. macal sp. nov. and A. ocotal sp. nov. A larger symbol denotes the type locality (uncertain for A. angustifrons).

Figure 31. Astyanax caballeroi, live, from Lake Catemaco, Mexico. © A.E. Gómez González. Reproduced by permission of A.E. Gómez González. Permission to reuse must be obtained from the rightsholder.