Astyanax dorioni ( Rosen 1970 ) 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 : 1382-1384

Astyanax dorioni ( Rosen 1970) comb. nov.

( Figure 24 ; see original description for illustration of holotype)

Bramocharax bransfordii dorioni Rosen 1970: 3 .

Bramocharax dorioni Rosen 1970 , auctt.

Diagnosis

Diagnosed from other Astyanax species in central-eastern Guatemala and Belize as follows: interorbital space, shorter than eye diameter (vs longer, except in A. baileyi ); postorbital length, mean 17% SL (vs mean less tha 15%); pelvic-fin length, 15% SL or more (15% or less, in A. baileyi ); supraoccipital in dorsal view short, wide based (long, narrow-based, in A. baileyi and A. belizianus ); maxillary teeth, more than 9 (4 or fewer in A. belizianus , A. brevimanus , A. cubilhuitz sp. nov., A. macal sp. nov. and A. petenensis ); caudad process of postcleithrum, square with no ventral concavity (no such concavity in A. cubilhuitz sp. nov. and A. macal sp. nov.).

Redescription

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

Head profile straight to strongly concave; snout elongated ( Bramocharax -like); lips even, mouth terminal. Pectoral fins almost always reach pelvic fin origin; anal and dorsal fins usually overlap. Lobes of caudal fin, subequal. See also Rosen (1970).

D. 10–11; A. 23–28 (the original description gives 25–30, including the first small spiniform rays), modally 24; pect. 12–17. Procurrent unsegmented dorsal rays on caudal fin, 9 or fewer. Gill rakers on first arch, 20–23, modally 22; on lower limb, 12–15, modally 13. Scales on lateral line, 34–37, modally 35 (the original description gives 37–40, probably including small scales on caudal-fin base); predorsal scales, 10–14, modally 12; scale rows from lateral line to base of first dorsal-fin ray, 6.5–8, modally 7; to base of pelvic fin, 5–6.5; to base of pectoral fin, 3.5–4; circumpeduncular scales, 13–15, mean 14.5. Scaly sheath on base of anal-fin, short, with imbricated scales. Nuptial tubercles, simple. Total vertebrae 32–33, 18–19 caudal. Detailed frequencies are given in Table 3.

Largest examined specimen, 99.5 mm SL. Body slender, 30–32% SL. Head length, 30–34% SL; orbital diameter, 27–29% HL; interorbital distance narrow, 6.1–7.8% SL, mean 7.0% SL (further morphometric data appear in Table 4).

Anterior fontanel long, straight-sided, sharp-tipped. Supraoccipital process in dorsal view, short, wide-based; slightly concave, in lateral view. Vomer, rostrally undulate. Dentigerous arm of premaxilla, much longer; 3–4 teeth. Highest tooth on dentary, first or third; posterior teeth, not abruptly smaller. Dorsal edge of longer articular arm, variable. Maxillary, with a convex anteroinferior edge; 9–13 teeth. Quadrate, dorsal process expanded. Arms of metapterygoid, subequal; 2 dorsorostral projections. Infraorbital II, triangular with an angled base; infraorbital III, inferoposteriorly semicircular; infraorbital IV, rectangular, with a projection; contact between infraorbitals II and III, wide. Urohyal rostral end turned up, blunt; its ventrorostral edge convex, its ventral apex almost at caudal end; ceratohyal foramen, drop-shaped; rostral vertices, round, ventral side, straight. Epibranchial III, insertion of uncinate process angled, the distal segment of the main body straight. Upper pharyngeal bones, S-shaped; lower pharyngeal plate single, its caudal side concave. Dorsal side of hyomandibular, convex. Opercle, 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, with a median convexity; ventral rim, straight; posteroventral edge, curved; 2 canals at angle. Five predorsal bony elements; rostral edge of first pterygiophore curved. Coracoid with 2–3 interdigitations in suture to cleithrum, a concave caudal edge, a single posteroinferior spine. Caudad process of postcleithrum, digitiform. Dorsal tip of scaphium, truncate; caudal tip, spiny; dorsoposterior edge, slightly concave. Neural spines under dorsal fin, straight. Postanal element, short. Sixth to eighth caudal vertebra from tail, with a haemal spine displaced caudad. Largest hypuric plate, rostral edge straight. Epuric plate on last neural spine, roundish.

Humeral spot, indistinct to P-shaped. Pigment uniformly distributed on anal fin, only the anteriormost distal edge lighter. Caudal spot, both on peduncle and on fin rays. In life, the species ‘is light amber, the gill cover has silvery reflections, and the fins of large adults, particularly the pelvic, anal, and caudal fins, are rosy. The pectoral and dorsal fins are clear or pale yellow. In half-grown and juvenile dorioni the fins usually are clear or pale yellow; the caudal fin sometimes has a pinkish wash’ ( Rosen 1970, p. 7).

Type material and depositor

Holotype AMNH 29411 , 99.5 mm SL, Río Semococh , ‘ 15 km by road south of Sebol’, Usumacinta River basin, Alta Verapaz, Guatemala, coll. D.E. Rosen and R. Bailey, 1971 . Paratypes: AMNH 29412 (49 specimens), 29413 (22), 29414 (6), AMNH 27816 SD (3); MCZ 48687 (2); UANL 5705 (4); UMMZ 187926 (23), 187930 (11), 187944 (8) . For collection data, see original description.

Distribution

Endemic to Alta Verapaz, Guatemala ( Figure 24 ).

Remarks

The species corresponds to clade Ic of Ornelas-García et al. (2008), in part. See remarks for A. baileyi .

Figures

Figure 24. Map of northern Central America, showing distribution localities of Astyanax baileyi, A. belizianus, A. brevimanus, A. cubilhuitz sp. nov., A. dorioni and A. petenensis. A larger symbol denotes the type locality.