Corydoras gryphus Tencatt & Britto & Pavanelli 2014, new species

Corydoras gryphus, new species

Figs. 1-3

Holotype. MNRJ 40770, 32.3 mm SL, Brazil, Paraná, Foz do Iguaçu, rio Paraná (near Ponte daAmizade), approximately 25°31’S 54°38’W, 15 Oct 1982, Biology team of the Universidade Estadual de Maringá.

Paratypes. MCP 47852, 6, 23.4-30.4 mm SL; MNRJ 40771, 6, 24.6- 31.9 mm SL; NUP 1572, 21, 21.9-35.0 mm SL; NUP 14676, 3 c&s,

27.7-32.4 mm SL; ZUEC-PIS 7656, 9, 25.5-31.8 mm SL, collected with the holotype.

Diagnosis. Corydoras gryphus is distinguished from its congeners by a conspicuously reduction on posterior laminar expansion of infraorbital 2, almost absent in some specimens (vs. infraorbital 2 with moderate- or well-developed posterior laminar expansion). The new species differs from its congeners, except C. longipinnis and C. tukano, by the presence of an uncommon sexual dimorphic condition, with the conspicuous elongation of the first and second branched dorsal-fin rays in males surpassing dorsal-fin spine distal tip, with size similar to the total length of the spine (vs. dorsal fin not sexually dimorphic with respect to its length; or elongation of dorsal-fin elements (when present) not associated with sexual dimorphism; or dorsal fin, if sexually dimorphic, with first and second dorsal-fin branched rays slightly surpassing dorsal-spine distal tip). The new species is also distinguished from C. longipinnis and C. tukano by the presence of four to six irregular black or brownish blotches on the midline of the flank (vs. midline of the flank with three large black rounded blotches in C. longipinnis; two very large black rounded blotches in C. tukano). Corydoras gryphus is further distinguished from C. longipinnis by having the mesethmoid not visible, entirely covered by a thick layer of skin (vs. visible, posterior portion of mesethmoid covered by a very thin epidermal layer). See additional diagnostic features in the discussion.

Description. Morphometric data in Table 1. Head compressed with slightly convex dorsal profile; triangular in dorsal view. Snout slightly pointed. Head profile convex from snout to tip of posterior process of parieto-supraoccipital. Profile slightly convex along dorsal-fin base. Body profile between dorsal fin and adipose-fin spine slightly concave; concave from that point to caudal-fin base. Ventral profile of body nearly straight from isthmus to pectoral girdle; slightly convex from that point to pelvic girdle. Profile nearly straight from pelvic girdle to base of first anal-fin ray; concave from that point to caudal-fin base. Body roughly elliptical in cross section at pectoral girdle, gradually becoming more compressed toward caudal fin.

Eye rounded, located dorso-laterally on head; orbit delimited dorsally by frontal and sphenotic, ventrally by infraorbitals. Anterior and posterior nares close to each other, only separated by flap of skin.Anterior naris tubular. Posterior naris close to anterodorsal margin of orbit, separated from it by distance equal to diameter of naris. Mouth small, subterminal, width nearly equal to bony orbit diameter. Maxillary barbel moderate in size, not reaching anteroventral limit of gill opening. Outer mental barbel slightly longer than maxillary barbel. Inner mental barbel fleshy, with base close to its counterpart. Small rounded papillae covering entire surface of all barbels, upper and lower lips, and isthmus.

Mesethmoid short, totally covered by thin layer of skin. Nasal elongate and slender, smoothly curved laterally, inner margin laminar; mesial border contacting frontal and mesethmoid; with two nasal pores. Frontal elongated, narrow, width less than half entire length; anterior projection short, size smaller than nasal length; epiphysial branch of supraorbital canal short, pore opening mesially on frontal. Frontal fontanel large, oval; posterior tip extension entering anterior margin of parieto-supraoccipital. Parieto-supraoccipital wide, posterior process long and contacting nuchal plate. Two laminar infraorbitals with minute odontodes; infraorbital 1 moderately developed, relatively slender; anterior portion with moderate expansion (Fig. 2a); infraorbital 2 small, conspicuously slender, with posterior laminar expansion very reduced (Fig. 2a), almost imperceptible in some specimens; posteroventral margin contacting supra-preopercle, dorsal tip contacting sphenotic. Interopercle covered by thin layer of skin, somewhat triangular, with anterior projection well developed. Preopercle slender, elongated, with minute odontodes sparse on external surface. Opercle elongated in shape, width nearly equal to, or smaller than half of its length; free margin smooth, without serrations and covered with small odontodes. Anteroventral portion of cleithrum exposed; posterolateral portion of scapulocoracoid exposed; minute odontodes sparse on exposed areas. Vertebral count 23(3); ribs 6(3), first pair conspicuously larger.

Four branchiostegal rays decreasing in size posteriorly. Hypobranchial 2 somewhat triangular, tip ossified and directed towards anterior portion, posterior margin cartilaginous; ossified portion well developed, about twice size of cartilaginous portion. Five ceratobranchials with expansions increasing posteriorly; ceratobranchial 1 with small process on anterior margin of mesial portion; ceratobranchial 3 notched on postero-lateral margin; ceratobranchial 5 toothed on postero-dorsal surface, 33(1) or 34(2) teeth aligned in one row. Four epibranchials with similar size; epibranchial 2 slightly larger than others, with small pointed process on laminar expansion of posterior margin; epibranchial 3 with uncinate process on laminar expansion of posterior margin. Two wide pharyngobranchials, pharyngobranchial 3 lacking process on posterior margin. Upper tooth plate oval; 33(1) or 39(2) teeth aligned in two rows on postero-ventral surface.

Dorsal fin roughly triangular, located just posterior to second dorsolateral body plate. Dorsal-fin rays II,8(20), posterior margin of dorsal-fin spine with 14 to 25 serrations, disposed along entire length of spine; proximal portion of dorsal spine without serrations in some specimens. Nuchal plate exposed with minute odontodes; spinelet short; dorsalfin spine very long, adpressed distal tip almost reaching or reaching to adipose-fin origin, its posterior margin with small odontodes. Pectoral fin triangular, its origin just posterior to gill opening. Pectoral-fin rays I,7(20); posterior margin of pectoral spine with 23 to 33 moderately developed serrations, disposed generally along entire length of posterior margin; simple and bifid serrations (Fig. 3). Pelvic fin oblong, located just below first ventrolateral body plate, and at vertical through first branched dorsal-fin ray. Pelvic-fin rays i,5(20). Adipose fin roughly triangular, separated from base of last dorsal-fin ray by generally seven dorsolateral body plates. Anal fin triangular, located just posterior to 12 th ventrolateral body plates, and at vertical through anterior margin of adipose-fin spine. Anal-fin rays i,6(20). Caudal fin forked. Caudal-fin rays i,12,i(20), generally three dorsal and three ventral procurrent rays; caudal-fin bilobed, lobes similar in size.

Three or four laterosensory canals on trunk; first ossicle tubular, second ossicle laminar, third and fourth canals fused to third and fourth dorsolateral body plates, respectively. Body plates with minute odontodes scattered over exposed area, and conspicuous line of odontodes confined on posterior margins; dorsolateral body plates 23*(16) or 24(4); ventrolateral body plates 20(6) or 21*(14); dorsolateral body plates along dorsal-fin base 5(6) or 6*(14); dorsolateral body plates between adipose and caudal fins 6(3), 7*(16) or 8(1); preadipose platelets 2(4) or 3*(16), adipose spine opposed to anal-fin insertion; small platelets covering base of caudal-fin rays; small platelets disposed dorsally and ventrally between junctions of lateral plates on posterior portion of caudal peduncle. Anterior margin of orbit with platelets, above posterior portion of lateral ethmoid and above junction of frontal and lateral ethmoid; posterior and ventral margins of nasal capsule with platelets. Lateral portion of snout with platelets in some specimens (Fig. 2a). Ventral surface of body with few irregular platelets; platelets absent in some specimens.

Color in alcohol. Ground color of body brownish yellow, with top of head dark brown. Head without spots. Region of nasal bone dark. Opercle with pale border; anterior portion dark brown. Upper portion of dorsolateral plates dark blotched. Dorsal series of four dark brown blotches, first on anterior portion of dorsal-fin base, second on posterior portion of dorsal-fin base, third on adipose-fin base and fourth on caudal-fin base. Midline of flank with four to six irregular black blotches, different in size from each other, generally elongated transversally. Inferior portion of ventrolateral body plates generally dark spotted posteriorly to pelvic fin. Dorsal and pectoral fins scarcely dark mottled. Pelvic fin hyaline. Adipose fin generally with hyaline membrane and with darkened area on distal portion of membrane in some specimens. Middle portion of anal fin with black blotch. Middle portion of caudal-fin base with small black dot. Caudal fin with three or four transverse black bars.

Sexual dimorphism. Corydoras gryphus presents a sexual dimorphism very similar to that described for C. tukano and C. longipinnis, with the first and second branched dorsal-fin rays conspicuously elongated in males, almost reaching caudal-fin origin in some specimens. The first branched ray of the pectoral fin is elongated in males. The dorsal- and pectoral-fin spines are well-developed in both sexes but are slightly larger in adult males. Dorsal- and pectoral-fin spines have segmented expansions, similar to those exhibited by Aspidoras Ihering and Scleromystax Günther. Infraorbital 1 has well-developed odontodes in males.

Distribution. Corydoras gryphus is known from its type locality, the lower rio Paraná, near Itaipu dam (Fig. 4).

Etymology. From the Latin, the specific name gryphus means griffon, mythical creature with a lion body and a head and wings of a hawk or eagle, in allusion to the conspicuous elongation of pectoral-fin spine and its first branched ray, like a wing in male specimens. A noun in apposition.

Remarks. Fuller & Evers (2011: 64-65) mentioned the presence of an undescribed species from the Misiones Province, Argentina (Fig. 5). The presence of irregular and slightly vertically elongated small black blotches along midline of the flank is shared between the new species and Corydoras sp. ‘Misiones’ (see Figs. 1, 5). On the other hand, Corydoras sp. ‘Misiones’ present irregular and striated black spots on the snout and dorsal portion of the head, which are absent in C. gryphus. However, Corydoras sp. ‘Misiones’ present the same unusual sexual dimorphism of C. gryphus, C. longipinnis and C. tukano. Additionally, through the analysis of high-definition photographs, it was possible to observe that Corydoras sp. ‘Misiones’ also presents a reduced laminar expansion of infraorbital 2 and relatively slender infraorbital 1, similar to C. gryphus condition. Furthermore, the type locality of C. gryphus is relatively near to the territory of Misiones Province. Despite the similarity between the new species and Corydoras sp. ‘Misiones’, the precise confirmation that they are the same species can only be made through the analysis of preserved specimens of Corydoras sp. ‘Misiones’.