Astyanax ocotal Valdez-Moreno, Rodiles-Hernández 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 : 1396-1398

Astyanax ocotal Valdez-Moreno, Rodiles-Hernández and Schmitter Soto sp. nov.

( Figures 15 , 39 , 40 )

Bramocharax sp. , Rodiles Hernández 2005, Valdez-Moreno 2005, Jelks et al. 2008.

Diagnosis

Diagnosed from other Astyanax species in the region as follows: head length, 29–33% SL (22– 28% in A. angustifrons and A. fi nitimus, to 30% in A. aeneus ); anal-fin base length, 26% SL or less (26% or more in A. aeneus and A. fi nitimus); lower-limb gill rakers in first arch, 15–16 (14 or fewer in A. angustifrons and A. fi nitimus); urohyal, ventral apex closer to caudal end (about equidistant between rostral and caudal ends in A. fi nitimus); epibranchial III, distal segment straight (curved in A. fi nitimus); preopercle with divergent canals at angle (canals parallel in A. angustifrons ); coracoid with 4–5 interdigitations in suture to cleithrum (2–3 in A. angustifrons ).

Redescription

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

Head profile, concave; snout elongated, Bramocharax- like. Lips even; mouth terminal. Pectoral fins may reach pelvic fin origin or not; anal and dorsal fins usually do not overlap. Lobes of caudal fin, subequal.

D. 9; A. 22–24; pect. 10–12. Procurrent unsegmented dorsal rays on caudal fin, variable. Gill rakers on first arch, 24–25; on lower limb, 15–16. Scales on lateral line, 32–34; predorsal scales, 11; scale rows from lateral line to base of first dorsal-fin ray, 7 – 7.5; to base of pelvic fin, 6; to base of pectoral fin, modally 4, up to 4.5; circumpeduncular scales, 16. A single, short scale row on anal fin base. Nuptial tubercles, not seen. Total vertebrae 31, 18–19 caudal. Detailed frequencies are given in Table 3.

Largest examined specimen, 105.1 mm SL. Body depth, 31–37% SL. Head length 29–33% SL; orbital diameter, 26–33% HL; interorbital distance, 7.8–10.4% SL, mean 9.1% SL (further morphometric data appear 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. Highest tooth on dentary, first or third. Dorsal edge of longer articular arm, convex. Maxillary, with a convex anteroinferior edge, 4 teeth. Metapterygoid, rostral arm longer than ventral; 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, pointed, its ventrorostral edge uniform, its ventral apex closer to caudal end; no ceratohyal foramen; rostral vertices of ceratohyal angled, the ventral side straight. Epibranchial III, insertion of uncinate process round, 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. Opercular dorsal edge, concave-convex; sides of dorsal half, parallel; caudoventrally straight-convex, caudodorsally concave; ventral tip, sharp. Interopercular posterior edge, straight-convex, with a spine. Preopercular ventral rim, straight; posteroventral edge, curved; 2 canals at angle, divergent. Coracoid with 4–5 interdigitations in suture to cleithrum, a concave caudal edge, a single posteroinferior spine. Caudad process of postcleithrum, digitiform. Dorsal tip of scaphium, sharp; caudal tip, truncate; dorsoposterior edge, undulate. Fifth caudal vertebra from tail, with a haemal spine displaced caudad. Hypuric plate on last haemal spine, with straight rostral and caudal borders. Epuric plate on last neural spine, edge straight.

Humeral spot, indistinct. Pigment on anal fin sparse, rather concentrated on middle of rays. Caudal spot, both on peduncle and on fin rays. Caudal yellow in life, at least in central rays ( Figure 39 ).

Type material and depositor

Holotype UMMZ 250292, 105.1 mm SL, ‘ Laguna Ocotal , Lacandon region, elev. 3100 ft [sic; actually it is only 840 m], lies ca. 75 airline km ESE of Ocosingo’, northern Chiapas, Mexico, coll. R. A. Paynter, Jr., June 1954 ( Figure 40 ) . Paratypes: UMMZ 171139 (4 specimens), same collection data; ECOSC 176 (1 specimen), Lake Metzabok, Ocosingo, Mexico.

Etymology

Named after the type locality. A noun in apposition.

Distribution

Endemic to Lakes Ocotal and Metzabok, and Río Tulijá, northern Chiapas, Mexico ( Figure 15 ). Second only to A. mexicanus in altitude.

Proposed common names

Lacandon tetra, pepesca lacandona (after Jelks et al. 2008).

Remarks

The species was independently detected by Valdez-Moreno (2005) and by Rodiles- Hernández (2005). Its inclusion in the endangered species list of Jelks et al. (2008) as Threatened, under the name Bramocharax sp. , is based on an opinion by the late S. Contreras-Balderas.

Lake Ocotal, an endorheic, highland basin, is home to at least another endemic fish: Rocio ocotal ( Schmitter-Soto 2007) . The specimens from Río Tulijá display some meristic differences, such as a higher number of anal-fin rays.

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 39. Astyanax ocotal sp. nov., live at Río Tulijá, Chiapas. © A. E. Gómez González. Reproduced by permission of A. E. Gómez González. Permission to reuse must be obtained from the rightsholder.

Figure 40. Astyanax ocotal sp. nov., holotype, UMMZ 250292.