Astyanax finitimus ( Bocourt 1868 )

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 : 1384-1387

Astyanax finitimus ( Bocourt 1868)

( Figures 7 (b), 15, 33, 34)

Tetragonopterus fi nitimus Bocourt 1868: 62.

Tetragonopterus streetsii Cope 1872: 217 .

Astyanax rutilus , « variety? » [sic] Eigenmann and Ogle 1907

Tetragonopterus macrophthalmus Regan 1908: 171 .

Astyanax armandoi Lozano-Vilano and Contreras-Balderas 1990 .

Astyanax aeneus × mexicanus, Valdez-Moreno 1997 .

Astyanax fasciatus ? Lima et al. 2003.

Astyanax aeneus non Günther, partim. Schmitter-Soto et al. 2008, d’ Artola Barceló 2009, Miller et al. 2009, and others.

Astyanax ‘Veracruz’, Schmitter-Soto 2016.

Diagnosis

Diagnosed from other Astyanax species in Veracruz and neighbouring areas as follows: total gill rakers on first arch, mean 21 (mean 18–19 in A. acatlanensis , A. tamiahua and A. tehuacanensis sp. nov.); average number of gill rakers on lower arm of first arch, fewer than 12 (15 or more in A. angustifrons ; 12 or more in A. caballeroi ); longest dorsal-fin ray, mean 23.6% SL (mean 25.4% in A. aeneus ); distance between origins of pelvic and anal fins, 16–19, mean 17.4% SL (18–22, mean 20.2% in A. aeneus ); anterior fontanel, short (longer in A. aeneus , A. angustifrons and A. caballeroi ), its sides straight (convex in A. tamiahua sp. nov.), its tip blunt (sharp in A. caballeroi and A. tamiahua sp. nov.); supraoccipital long, narrow-based (short, wide-based in A. tamiahua sp. nov.); infraorbital II, with an angled base (base convex in A. aeneus ); contact between infraorbitals II and III, wide (narrower in A. aeneus ).

Redescription

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

Head profile, straight to slightly concave; snout obtusely angled to squarish. Lips even, mouth terminal. Pectoral fins usually reach pelvic fin origin; anal and dorsal fins may overlap. Lobes of caudal fin, subequal.

D. 9–11; A. 21–29, mean 24.5; pect. 10–12. Procurrent unsegmented dorsal rays on caudal fin, usually 9 or fewer. Gill rakers on first arch, 19–23, modally 21; on lower limb, 9–13, modally 12. Scales on lateral line, 31–36, modally 34; predorsal scales, 9–13, modally 12; scale rows from lateral line to base of first dorsal-fin ray, 6–7.5, modally 7; to base of pelvic fin, 5.5–7, modally 6; to base of pectoral fin, 3–4.5, modally 4; circumpeduncular scales, 14–17, modally 16. A single, short scale row on anal fin base. Nuptial tubercles, simple. Total vertebrae 32–33 (exceptionally 31), 18–19 caudal. Detailed frequencies are given in Table 3.

Largest examined specimen, 79.6 mm SL. Body depth, 32–40% SL. Head 22–26% SL; orbital diameter, 28–37% HL; interorbital distance, 7.2–10.9% SL, mean 8.2 (further morphometric data appear in Table 4).

Anterior fontanel long, straight-sided, blunt-tipped. Supraoccipital process in dorsal view, short, wide-based; angled in lateral view. Vomer rostrally slightly concave. Arms of premaxilla, subequal; 0–4 teeth. Highest tooth on dentary, first or third; posterior teeth, variable. Dorsal edge of longer articular arm, variable. Maxillary, with a convex anteroinferior edge; 1–3 teeth. Quadrate, dorsal process not expanded. Metapterygoid, rostral arm longer than ventral; dorsocaudad projections, usually 2. Infraorbital II, triangular, with an angled base. Infraorbital III, usually inferoposteriorly semicircular; infraorbital IV, squarish with a projection; a wide contact between infraorbitals II and III. Urohyal rostral end turned up, pointed, its ventrorostral edge convex; ceratohyal foramen oval. Epibranchial III, distal segment curved, insertion of uncinate process usually round. Upper pharyngeal bones, usually oval; lower pharyngeal plate, single; its caudal side, concave. Hyomandibular, variable. Opercle, sides of dorsal half, parallel; caudoventrally straight-convex, caudodorsally concave. Interopercular posterior edge, straightconvex. Preopercular posteroventral edge, curved; 2 canals at angle, usually parallel. Four or 5 predorsal bony elements; rostral edge of first pterygiophore angled. Coracoid with 2 or 3 interdigitations in suture to cleithrum, a concave caudal edge, 1 posteroinferior spine. Caudad process of postcleithrum, with parallel sides and convex tip to globose. Proximal edge of pelvic bone, convex. Postanal element, short. Neural spines under dorsal fin, usually straight. Fifth to seventh caudal vertebra from tail, with a haemal spine displaced caudad. Hypuric and epuric plates, variable.

Humeral spot, rectangular-triangular. Pigment on anal fin, uniformly sparse. Caudal spot, both on peduncle and on fin rays ( Figure 33 ).

The species (as ‘ A. aeneus ’ from Tabasco) has 50 chromosomes, 1 metacentric pair + 2 submetacentric + 22 subtelocentric ( d’ Artola Barceló 2009).

Type material and depositor

Lectotype MNHN 2016–321, 110 mm SL, coll. M. Bocourt, near Orizaba, Veracruz, Mexico (not ‘Chinautla, Guatemala’; see Remarks) ( Figure 34 ) . Paralectotype MNHN 5223, same collection data as lectotype.

Distribution

Gulf coast of Mexico, states of Veracruz, Tabasco, and northern Oaxaca and Chiapas ( Figure 15 ) .

Proposed common names

Veracruz tetra, sardinita de Veracruz.

Remarks

Bocourt (1868) conflated his two type specimens under only one catalogue number at MNHN, stating in the original description only one locality: ‘environs d’ Orizaba’ . The mention of Chinautla as another locality is probably a labeling mistake, since the syntypes are not identifiable as any species in Guatemala . Therefore, the name A. fi nitimus is considered available for the species in the Mexican Gulf coast. The original description states that interorbital distance is larger than eye diameter; this is statistically true, although the full range of both measurements overlaps.

There are several clines in meristic traits along the distributional range of A. fi nitimus; for example, there is an increasing trend from south to north in number of anal-fin rays, and north to south in number of scale rows between lateral line and dorsal-fin origin. Because many of these clines seemed intergradations between southern and northern forms, Valdez-Moreno (1997) considered the populations of Astyanax between the Solteros and Antigua rivers (comprising the type localities of A. fi nitimus and T. macrophthalmus ) to be ‘intermediate’ between A. aeneus and A. mexicanus .

See comment on the doubtful synonymy of A. oaxacanensis under the remarks for A. aeneus and in the Discussion. The species T. macrophthalmus and T. streetsii have type localities within the distribution of A. fi nitimus and correspond to this resurrected species with little doubt, except that Regan (1908) gave up to 40 scales in a longitudinal series for T. macrophthalmus , a figure that I cannot confirm in the respective syntypes. Regan (1908) placed T. streetsii in the synonymy of A. mexicanus , for no explicit reason. Astyanax armandoi was synonymised with ‘ A. aeneus ’ (= A. fi nitimus) by Schmitter-Soto et al. (2008).

This species is part of lineage Ib of Ornelas-García et al. (2008) and also part of clade B of Strecker et al. (2004).

Figures

Figure 7. (a) An anterior fontanel, sharp-ended, sides convex at mid-length (arrow) (Astyanax argentatus, UMMZ 169835); (b) fontanel blunt-ended, sides straight (arrow) (A. finitimus, UMMZ 97336).

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 33. Astyanax finitimus live at Ajal River, Coatzacoalcos drainage. © J.M. Artigas Azas. Reproduced by permission of J.M. Artigas Azas. Permission to reuse must be obtained from the rightsholder.

Figure 34. Astyanax finitimus, lectotype. MNHN 2016-321. © MNHN - C. Ferrara. Reproduced by permission of MNHN - C. Ferrara. Permission to reuse must be obtained from the rightsholder.