Astyanax cubilhuitz, 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 : 1380-1382

Astyanax cubilhuitz sp. nov.

( Figures 24 , 32 )

Astyanax ‘Cubilhuitz’, Schmitter-Soto 2016.

Diagnosis

Diagnosed from other Astyanax species in north-eastern Guatemala and Belize as follows: body depth, 35% SL or less (35% or more in A. bacalarensis sp. nov. and A. belizianus ); eye larger, diameter 35% HL (vs 32% or less); mean predorsal length, 52% SL (49% in A. macal sp. nov. and A. petenensis ); mean anal-base length, 26% SL (vs 28% or more); longest anal-fin ray, mean 17% SL (vs 14%); upper pharyngeal plate, oval (crescent-shaped, in A. belizianus ); humeral spot, rectangular (vs indistinct or P-shaped).

Description

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

Head profile straight; snout round. Lips even; mouth terminal. Pectoral fins always reach pelvic fin origin; anal and dorsal fins may overlap. Lobes of caudal fin, subequal.

D. 9; A. 21–26, modally 23; pect. 12. Procurrent unsegmented dorsal rays on caudal fin, 10 or more. Gill rakers on first arch, 21–23, modally 22; on lower limb, 12–14, modally 13. Scales on lateral line, 34–38, mean 36.5; predorsal scales, 12–13; scale rows from lateral line to base of first dorsal-fin ray, 6.5–8, modally 7; to base of pelvic fin, modally 6, up to 6.5; to base of pectoral fin, 3.5–4; circumpeduncular scales, 13–16, mean 15. A single scale row on anal fin base, rather short. Nuptial tubercles not seen. Total vertebrae 32–33, 18–19 caudal. Detailed frequencies are given in Table 3.

Largest examined specimen, 53.0 mm SL. Body slender, 32–35% SL. Head length, 25–28% SL; orbital diameter somewhat large, 33–37% HL; interorbital distance, 7.2–9.1% SL, mean 7.9% SL (further morphometric data are given in Table 4).

Anterior fontanel long, straight-sided, blunt-tipped. Supraoccipital process in dorsal view, short, wide-based; slightly concave in lateral view. Vomer rostrally slightly concave. Dentigerous arm of premaxilla, longer; 0–4 teeth. Highest tooth on dentary, first or third; posterior teeth, abruptly smaller. Dorsal edge of longer articular arm, straight. Maxillary, with a convex anteroinferior edge; 1–3 teeth. Quadrate, dorsal process expanded. Metapterygoid, rostral arm longer than ventral, 2 dorsorostral projections. Infraorbital II, triangular with an angled base; infraorbital III, inferoposteriorly semicircular; infraorbital IV, squarish with a projection; a wide contact between infraorbitals II and III. Urohyal rostral end turned up, blunt, its ventrorostral edge convex, its ventral apex about equidistant between the rostral and caudal ends; ceratohyal foramen oval; rostral vertices of ceratohyal round, the ventral side straight. Epibranchial III, insertion of uncinate process angled, the distal segment of the main body straight. Upper pharyngeal bones, oval. Dorsal side of hyomandibular, convex. Opercular dorsal edge, convex; 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, straight; posteroventral edge, curved; 2 divergent canals at angle. Five predorsal bony elements, distally expanded; rostral edge of first pterygiophore angled. Coracoid with 1 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. Dorsal tip of scaphium, truncate; caudal tip, sharp; dorsoposterior edge, slightly concave. Neural spines under dorsal fin, straight. Sixth caudal vertebra from tail, with a haemal spine displaced caudad. Rostral edge of largest hypuric plate, pointed. Epuric plate on last neural spine, distally spiny.

Humeral spot, approximately rectangular. Pigment on anal fin, uniformly sparse. Caudal spot, both on peduncle and on fin rays.

Type material and depositor

Holotype UMMZ 250290 , 53.0 mm SL, ‘spring origin of short stream with underground drainage to Río Dolores , Cubilhuitz, elevation 300 m, Icbolay’, Alta Verapaz, Guatemala, coll. D.E. Rosen and R. Bailey, 1968 ( Figure 32 ) . Paratypes: UMMZ 188007, 55 specimens, same collection data as holotype.

Etymology

Named after the type locality. A noun in apposition.

Distribution

Río Dolores, a stream near Cubilhuitz isolated by a subterranean segment, Alta Verapaz, Guatemala ( Figure 24 ).

Proposed common names

Cubilhuitz tetra, sardinita del Cubilhuitz.

Remarks

Although probably not syntopic with A. cubilhuitz sp. nov., several fish species are endemic to this karstic region, such as poeciliids in genera Xiphophorus and Heterandria ( Rosen 1978, 1979).

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.

Figure 32. Astyanax cubilhuitz sp. nov., holotype. UMMZ 250290.