Chinchaysuyoa ortegai, Marceniuk & Marchena & Oliveira & Betancur-R, 2019

Marceniuk, Alexandre Pires, Marchena, Jose, Oliveira, Claudio & Betancur-R, Ricardo, 2019, Chinchaysuyoa, a new genus of the fish family Ariidae (Siluriformes), with a redescription of Chinchaysuyoa labiata from Ecuador and a new species description from Peru, Zootaxa 4551 (3), pp. 361-378 : 368-372

Chinchaysuyoa ortegai new species

Figure 4 , 5 , 6 , Table 1.

Hexanematichthys henni (non Fisher & Eigenmann).— Chirichigno 1963:27 (Tumbes).— Ortega & Vari 1986:13 (species list).— Ortega et al. 2012:42 (species list).

Holotype: MUSM 63800 , 250 mm SL, reservoir Poechos , middle Rio Chira, Catamayo basin, Peru.

Paratype: ANSP 282226 (1, 229 mm SL), the same locality of the holotype; MPEG 35976 (2, 209– 300 mm SL), the same locality of the holotype; MZUSP 123828 (2, 252– 292 mm SL). the same locality of the holotype; MUSM 48796 (5, 155– 250 mm SL), the same locality of the holotype; USNM xxxx (2, 18 7 –206 mm SL), the same locality of the holotype .

Diagnosis. Chinchaysuyoa ortegai differs from C. labiata by thicker granulation irregularly distributed granulation in the cephalic shield (vs. finer and homogeneously distributed in the cephalic shield, especially in the sphenotic, pterotic and parieto-supraoccipital, Figs. 5 and 6 ), snout truncated anteriorly (vs. pointed anteriorly, Fig. 5 ), distance between anterior nostrils 6.3–7.6% SL (vs. 5.1–5.9% SL, Table 1), distance between posterior nostrils 6.4–7.5% SL, rarely less than 6.4 (vs. 5.2–6.2% SL, Table 1), caudal–fin lobes relatively, rounded posteriorly (vs. relatively long, pointed posteriorly, Fig. 5 ).

Description. Morphometric data in Table 1. Head depressed, profile elevated posteriorly, straight at frontal and parieto-supraoccipital area. Snout long and previously truncated. Anterior nostril round, with fleshy edge, posterior nostril covered by flap of skin; nostrils distant to one another and distant to orbit, not connected by fleshy furrow. Eye lateral and large; eyes distant to one another. Three pairs of relatively long teretiform barbels; maxillary barbel usually reaching or past reaching gill membrane edge, mental barbels not reaching gill membrane edge. Osseous bridge formed by lateral ethmoid and frontal relatively long and slender, little evident under skin. Cephalic shield exposed, very rough and granulated; long and large on lateral ethmoid, frontal, and supracleithral areas. Anterior portion of dorsomedial groove of neurocranium fleshy, conspicuous and continuous to level of posterior nares; posterior portion of osseous groove, deep and conspicuous, with straight margins, narrowing posteriorly. Parietosupraoccipital process funnel-shaped, long and moderately wide on posterior portion, and profile straight. Nuchal plate crescent-shaped, long and moderately wide.

Mouth subterminal to terminal, moderately large; lower jaw arched. Lips relatively thick, upper lip more thick than lower lip. Vomerine tooth plates absent. One pair of oval shaped accessory tooth plates, very small and transversely elongate and narrow, distant one another, with sharp teeth. Premaxilla with sharp teeth. Dentary separated at midline, with sharp teeth. Gill membranes fused, attached to isthmus. Eighteen to twenty acicular gill rakers on first arch, 20–23 spike-shaped gill rakers on second arch. Mesial surfaces of all gill arches with developed gill rakers, lateral and mesial surfaces of first and second gill arches lacking fleshy papillae intercalated with gill rakers.

Body width wider than depth in pectoral-girdle area, progressively more compressed from pectoral fin to caudal peduncle. Lateral line sloping ventrally on anterior one-third, extending posteriorly to caudal peduncle, bending abruptly onto dorsal lobe of caudal fin. Dorsal-fin spine moderately long and thick; anterior margin with granules on basal two-thirds and distal one-third with serrations; posterior margin smooth on basal half and distal half with serrations. Seven soft dorsal-fin rays. Pectoral-fin spine moderately long, shorter than dorsal-fin spine; anterior margin with granules on basal two-thirds and distal one-third with short serrations; posterior margin with granules on basal, distal half with serrations. Ten to eleven soft pectoral-fin rays. Posterior cleithral process exposed, rough and triangular shaped, very long and pointed posteriorly. Pelvic fin deep and moderately long at base, with six rays. Adipose-fin base relatively long, its base about half as long as the anal-fin base. Anal fin deep and relatively long at base, with 19–20 rays and distal margin slightly concave. Caudal peduncle relatively deep. Caudal fin forked, dorsal and ventral lobes moderately long, wide and rounded posteriorly; dorsal lobe longer than ventral lobe.

Coloration. Grayish to dark brown on dorsum, silvery on flanks and white on abdomen. In alcohol, dark brown on dorsum, flanks brownish to silvery and white on venter; fins black. Maxillary barbel dark, mental barbel lighter ( Figs. 4a,b , 5 ).

Distribution and habitat. Chinchaysuyoa ortegai is described to Poechos reservoir, in the middle Rio Chira in Peru, Catamayo Basin, that born in the Andes Occidental Cordillera in Ecuador ( Fig. 8 ).

Etymology. The name of the species is in honor of Dr. Hernán Ortega Torres Teofilo the most important ichthyologist working in Peru.

Remarks. Chinchaysuyoa ortegai can be differentiated from C. labiata based on its morphological characters (see Remarks on C. labiata ), which is further reinforced by the disjunct geographic ranges of the two species, which are restricted to the drainage basins of Ecuador and Peru, respectively ( Fig. 8 ), while the molecular data support the recognition of the species as distinct from the other genera of the family recorded on the Pacific coast of the Americas ( Fig. 1 ).

Figures

FIGURE 1. Phylogenetic tree inferred from combined evidence from molecular and morphological data based on Parsimony Analysis (A), Bayesian inference (B) and Maximum Likelihood (C), with bootstrap values greater than 50%. In red, neotropical freshwater species, included in Potamarius sensu Marceniuk & Menezes (2007).

FIGURE 4. Body in lateral view. Chinchaysuyoa labiata, (A) holotype 475 mm SL (MZUT 1540), (B) Hexanematichthys henni, holotype 139 mm SL (CAS 60620), (C) Chinchaysuyoa ortegai, holotype 256 mm SL (MUSM 63800), and (D) fresh non type specimen, not cataloged, 315 mm SL.

FIGURE 5. Head in dorsal view. Chinchaysuyoa labiata, (A) holotype 475 mm SL (MZUT 1540), and Chinchaysuyoa ortegai, (B) holotype 256 mm SL (MUSM 63800).

FIGURE 6. Dorsal view of the neurocranium and the nuchal plate of Chinchaysuyoa labiata, (A) paratype 113 mm SL (CAS 60621), and Chinchaysuyoa ortegai, (B) paratype 155 mm SL (MPEG 35976).

FIGURE 8. Sampling localities of the material examined in the present study, showing the geographic distribution of Chinchaysuyoa labiata, holotype (light blue circle), holotype and paratype of Hexanematichthys henni (red and pink circles, respectively), non–type specimen (yellow circle), and Chinchaysuyoa ortegai, type-specimens (green circle).