Astyanax yariguies ( Torres-Mejía, Hernández & Senechal, 2012 ) Ruiz-C & Román-Valencia & Taphorn & Buckup & Ortega, 2018

Ruiz-C, Raquel I., Román-Valencia, César, Taphorn, Donald C., Buckup, Paulo A. & Ortega, Hernán, 2018, Revision of the Astyanax orthodus species-group (Teleostei: Characidae) with descriptions of three new species, European Journal of Taxonomy 402, pp. 1-45 : 27-30

Astyanax yariguies ( Torres-Mejía, Hernández & Senechal, 2012) comb. nov.

Figs 4 , 12 , Table 1

Astyanacinus yariguies Torres-Mejía, Hernández & Senechal, 2012: 501 –506, figs 1–2. Original description, type locality: Rio Cascajales, Colombia.

Diagnosis

Astyanax yariguies is a member of the orthodus species-group of Astyanax , differing from the other members of the group, except for A. orthodus , in having a short polygonal caudal-peduncle spot (vs a cane-shaped mark that extends anteriorly to a vertical through the posterior anal-fin tip in A. superbus , an elongate mark that extends anteriorly to the humeral region in A. villwocki, and a short nail-shaped spot in A. bopiensis nom. nov. and A. boliviensis sp. nov.; spot on caudal peduncle inconspicuous in A. gandhiae sp. nov., and spot on caudal peduncle pentagonal, but extended towards dorsal and ventral margins of peduncle in A. embera sp. nov.). It differs from A. orthodus by the greater number of maxillary teeth (6 vs 2–3). It differs from most species of the orthodus -group in having 9–10 series of scales between the dorsal-fin origin and the lateral line (vs 7–8, except for A. bopiensis nom. nov. with 7–10). It is distinguished from A. moorii comb. nov. by orbital diameter greater than 31% HL (vs less than 31% HL), interorbital distance more 32% HL (vs less than 32% HL) and upper jaw length less than 35% HL (vs more than 45% HL).

Etymology

The species name refers to the Yariguíes, the indigenous group that inhabited an area that includes the watershed of the Cascajales River. They fiercely defended their pristine territory for more than 400 years, which likely contributed to the preservation of the species described here. The Yariguíes finally succumbed to invasion and extermination in the mid-20th century. The species name is treated as a noun in apposition ( Torres-Mejía et al. 2012).

Type material

Holotype (not examined)

COLOMBIA: 61.9 mm SL, Santander, El Carmen, Magdalena River system (Atlantic coast), Cascajales River drainage, Sucio River, under bridge on the road from El Carmen to Vereda Island ( UIST 1752 ) .

Material examined

Paratypes

COLOMBIA: 1 ♂, 6 ♀♀, 41.9–72.2 mm SL, Santander, Islandia locality, Magdalena River Basin, La Concordia Creek , 6°35′22.3″ N, 73°34′58.1″ W ( ICNMNH 17642 ) .

Description

Body compressed, greatest body depth at or anterior to origin of dorsal fin. Mouth terminal. Dorsal profile sigmoid between snout tip and posterior margin of supraoccipital spine (anterior part convex, posterior part concave), convex between head and dorsal fin, convex between head and at dorsal-fin base, convex between last ray of dorsal fin and origin of adipose fin. Caudal peduncle with straight dorsal and ventral profiles. Ventral profile convex between snout tip and insertion of pelvic fin.

Premaxillary teeth in two series; outer series with four tricuspid teeth covering three most medial teeth of inner series; inner row with five pentacuspid teeth. Maxilla long, of same width along entire length, with 2–3 tricuspid teeth set in anterior most part of ventral margin. Dentary with anterior four pentacuspid teeth, followed laterally by 8–10 teeth smaller, progressively inclined posteromedially, varying from tri- to unicuspid; proportion of tri- vs unicuspid teeth quite variable.

Pored lateral line scales 39(2), 40 (4); transverse scales from lateral line to dorsal-fin origin 9(1), 10 (5); scales from lateral line to anal-fin origin 7(1), 8(3), 9 (2); scales from lateral line to pelvic-fin insertion 6(1), 7(3), 8(2). Predorsal midline covered with bilobed medial scales for more than ¾ of its length, naked anteriorly. Dorsal-fin rays iii 9 (6), first simple ray small, easily visible only in C&S specimens, detectable with dissecting needle in non-C&S specimens; second simple ray about half length of third simple ray. Distal margin of dorsal fin slightly convex. Origin of adipose fin anterior to vertical through insertion of last ray of anal fin. Rays of pectoral fin i 10 (1), i 11 (1). Rays of pelvic fin i 7 (2). Rays of anal fin iii 28–30 (8), first simple rays only visible in cleared and stained material ( Table 1 ). Origin of anal fin posterior to vertical line through insertion of last dorsal-fin ray.

Total vertebrae 32(1), 35(1), including those of the Weberian apparatus: precaudal centra 16(1), 17(1); last three without pleural ribs; caudal centra 17(1)–19(1). Epipleurals 19–20. Epineurals 30–31, posterior-most epineural occasionally reaching anterior surface of urostyle. Hypurals 7 (2); first dorsal hypural with anterior margin swollen, without projections articulating with urostyle; second and third hypural with anterior margin swollen, contacting urostyle.

Pigmentation in alcohol

Sides of body yellowish, with reticulated pattern predominant over the lateral surface of the body. Silvery stripe between humeral region and caudal fin, overlain by series of chevron-shaped marks formed by dark lines along myosepta between myotomes extending from upper region of coelomic cavity to caudal peduncle; pigmented muscle septae forming chevrons not coinciding with scale rows. Chevrons without distal extensions both in juvenile and adult specimens.

Dorsal region of head and body chestnut brown. Sides of cranium and ventral surface of body light brown, not silvery. Melanophores of humeral region forming two spots. Anterior spot formed by two layers of pigment: brown melanophores distributed in a thin superficial layer of the epithelium (Layer 1, Fig. 1 ), deeper layer consisting of dark melanophores (Layer 2, Fig. 1 ). Layer 2 forms a polygon shaped spot, consisting of two groups of melanophores that do not precisely overlap, typically forming foursided spot extending from third to sixth or seventh scale of lateral series. Posterior humeral spot situated two or three scales posterior to the anterior humeral spot, arc- or sigmoid-shaped, inconspicuous, covering two to three scales above lateral-line. Caudal-peduncle spot short, elliptical in shape, not extending anteriorly to vertical through posterior margin of adipose fin. Pectoral, pelvic, dorsal and anal fins hyaline. Pigment present on interradial membranes of middle caudal-fin rays.

Sexual dimorphism

Males with small hooks on distal tips of rays of all fins: dorsal fin with hooks on third simple ray and on all branched rays; pelvic, anal and pectoral fins with hooks on branched rays; caudal fin with hooks on four middle rays.

Taxonomic comments

This species is transferred from Astyanacinus to Astyanax because it shares the anteriorly directed V-shaped chevrons along myomere junctions with members of the orthodus species-group. The conspicuous polygon-shaped humeral spot is also similar ( Fig. 1 ), consisting of dark melanophores.

Distribution

Astyanax yariguies is known from Colombia, the Magdalena River Basin and the Cascajales River drainage ( Fig. 4 ).

Figures

Fig. 4.Distribution of speciesof the Astyanaxorthodus species-group(symbol includestypelocalities).

Fig. 12. Astyanax yariguies (Torres-Mejía, Hernández & Senechal, 2012) comb. nov., paratype, 75.5 mm SL, La Concordia Creek, Santander, Colombia (ICNMNH 17642). Scale bar = 1 cm.

Fig.1.A.DistributionofpigmentinthehumeralregionofAstyanaxspecies.B.A.bimaculatus(Linnaeus, 1758).C.A.caucanus(Steindachner,1879).D.A.mexicanus(DeFilippi,1853).E.A.courensisBertaco, Carvalho & Jerep, 2010 (modified from Bertaco et al. 2010). The anterior humeral spot consists of two overlapping layers of pigment identified by numbers 1 and 2 (see Román-Valencia et al. 2015: fig. 1): 1. Diffuse vertical bar. 2. Horizontal spot with concentrated pigments.