Corydoras lymnades, Tencatt & Vera-Alcaraz & Britto & Pavanelli, 2013

Tencatt, Luiz F. C., Vera-Alcaraz, Héctor S., Britto, Marcelo R. & Pavanelli, Carla S., 2013, A new Corydoras Lacépède, 1803 (Siluriformes: Callichthyidae) from the rio São Francisco basin, Brazil, Neotropical Ichthyology 11 (2), pp. 257-264 : 258-262

Corydoras lymnades , new species

Fig. 1

Holotype. MNRJ 40186, 29.7 mm SL, Brazil , Minas Gerais , Guarda- Mor , rio Guarda-Mor, rio São Francisco basin, 17°46’18”S 47°05’ 43 ”W, 19 Jul 2008, C. H. Zawadzki, V. S. Ferreira, B. F. Morales & C. Pereira .

Paratypes. All from Brazil , rio São Francisco basin. Bahia. MNRJ 22370, 1, 22.5 mm SL, channel of the rio São Francisco , near the mouth of the rio Icatu, southeast of Ibaraba, 10°48’13”S 42°50’38”W, 15 Aug 2001, P. A. Buckup. Minas Gerais. MCP 16916 , 72, 16.0-

19.4 mm SL, 2 c&s, 16.0- 19.4 mm SL, Monte Azul, córrego Salinas, 15°12’53”S 43°15’49”W, 19 Jul 1993, R. Reis, J. Silva, E. Pereira & S. Schaefer. MCP 17047, 12, 16.5-21.6 mm SL, Montalvânia , rio Carinhanha in Juvenília, about 30 km NE of Montalvânia, 14°16’00”S 44°10’00”W, 16 Jul 1993, R. Reis, J. Silva & E. Pereira . MCP 17050, 20, 17.8-28.6 mm SL, 1 c&s, 17.8-28.1 mm SL, Manga , arroio in São João das Missões , on the road between Itacarambi and Manga, 14°52’46”S 44°05’00”W, 15 Jul 1993, R. Reis, J. Silva, E. Pereira & S. Schaefer . MCP 23492, 4, 17.0- 18.6 mm SL, Juvenília , rio Carinhanha on the farm of the Fundação Caio Martins, 14°15’00”S 44°09’00”W, 30 Jul 1993, H. Godinho . MCP 28271, 14, 22.5-28.3 mm SL, 2 c&s, 24.0- 27.7 mm SL, Guarda-Mor , córrego Macaúba , Coromandel / Guarda-Mor road, tributary to rio Claro, 17°58’57”S 47°06’41”W, 24 Jan 2001, C. Lucena, J. Silva, E. Pereira & A. Cardoso . MCP 29024, 3, 20.0- 23.9 mm SL, Januária , rio Peruaçu , on the border Januária / Itacarambi, 15°10’55”S 44°09’21”W, 14 Oct 2001, M. Brito & B. Nogueira . MCP 47023, 1, 24.8 mm SL, rio Peruaçu in the locality of Cachoeira , Januária / Itacarambi, 15°10’54”S 44°09’20”W, 30 Jul 2003, M. Brito & B. Nogueira . MCP 47024, 1, 24.7 mm SL, Januária , rio Peruaçu, Fabião I district, 15°10’37”S 44°12’32”W, 30 Jul 2003, M. Brito & B. Nogueira. NUP 9965, 13, 23.0-29.0 mm SL ; NUP 13834, 1 c&s, 24.7 mm SL ; NUP 13835, 1 c&s, 23.1 mm SL; all collected with the holotype .

Diagnosis. Corydoras lymnades is distinguished from most congeners, except C. aeneus , C. britskii , C. coppenamensis , C. difluviatilis , C. eques , C. garbei , C. multiradiatus , C. rabauti , C. splendens , and C. zygatus , by the anterior portion of the first infraorbital very large, conspicuously expanded towards the anteroventral margin of the snout and almost entirely covering its lateral margin (vs. anterior expansion small in C. hastatus , C. pygmaeus , and C. panda ; or anterior expansion large, but not covering significantly the lateral margin of the snout in remaining species of Corydoras ). The new species is distinguished from C. aeneus , C. britskii , C. difluviatilis , C. eques , C. garbei , C. multiradiatus , C. rabauti , C. splendens , and C. zygatus by the second infraorbital slender on its dorsal tip, contacting only sphenotic (vs. dorsal tip of second infraorbital wide, contacting sphenotic and compound pterotic by means of a triangular expansion). It is distinguished from C. coppenamensis by presence of two laterosensory canals on trunk (vs. three laterosensory canals on trunk). See additional diagnostic characters on identification key and discussion.

Description. Morphometric data presented in Table 1. Head compressed with slightly convex dorsal profile; roughly triangular in dorsal view. Snout rounded. Head profile convex from snout to tip of posterior process of parietosupraoccipital. Profile slightly convex along dorsal-fin base. Postdorsal body profile concave to adipose-fin spine; markedly concave from this point to caudal-fin base. Ventral profile of body nearly straight from isthmus to pectoral girdle; slightly convex from this point until pelvic girdle. Profile nearly straight from pelvic girdle to base of first anal-fin ray; slightly concave until caudal-fin base. Body roughly elliptical in cross section at pectoral girdle, gradually becoming more compressed towards caudal fin.

Eye roughly elliptical, largest orbit diameter in oblique axis between top of head and upper lip. Eye located dorsolaterally on head; orbit delimited dorsally by frontal and sphenotic, ventrally by infraorbitals. Anterior and posterior nares close to each other, only separated by a 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 elongate, reaching anteroventral limit of gill opening in some individuals. Maxillary barbel slightly longer than outer mental barbel. Inner mental barbel fleshy, base close to its counterpart. Small rounded papillae covering entire surface of all barbels, upper and lower lips, and isthmus.

Four branchiostegal rays decreasing in size posteriorly; distal tips of first two outer rays longer and connected to branchiostegal cartilage; distal tips of last two inner rays shorter, fourth ray about half length of first ray. Hypobranchial 2 roughly triangular, tip ossified and directed towards anterior portion, posterior margin cartilaginous; ossified portion well developed, about twice larger cartilaginous portion. Five ceratobranchials increasing in size 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, 23 to 31(3) teeth aligned in one row. Four epibranchials reducing size posteriorly; epibranchial 2 with small pointed process on laminar expansion of posterior margin, epibranchial 3 with small uncinate process on laminar expansion of posterior margin. Two wide pharyngobranchials (3 and 4), pharyngobranchial 3 with large triangular process on posterior margin. Upper tooth plate oval; 33 to 37(3) teeth aligned in two rows on postero-ventral surface.

Mesethmoid short, posterior portion partially exposed and possessing minute odontodes. Nasal slender, curved laterally, mesial border contacting mesethmoid and frontal. Frontal elongated, narrow, width less than half entire length; anterior projection long, size greater than nasal length; small process on antero-lateral margin; epiphysial branch of supraorbital canal short, pore opening located mesially on frontals. Frontal fontanel large, oval; anterior margin just posterior to middle of the eye, posterior margin extension variable, ending at parietosupraoccipital margin or slightly entering its anterior margin. Parietosupraoccipital wide, posterior process long and contacting nuchal plate. Two laminar infraorbitals with minute odontodes; infraorbital 1 large, anterior portion largely expanded, almost entirely covering lateral margin of snout ( Fig. 2a ), inner expansion large; infraorbital 2 small, postero-ventral margin contacting preopercle, dorsal tip slender, contacting sphenotic, inner expansion large. Interopercle covered by thick layer of skin, triangular, anterior projection short. Preopercle slender, elongated, small odontodes sparse on external surface. Opercle dorsoventrally elongated, length about two times width, free margin smooth, with sparse minute odontodes.

Dorsal-fin rays II,8*(30) or II,9(1) inner margin of dorsalfin spine with nine to 16 weak-developed serrations, concentrated on distal portion of spine; nuchal plate exposed with minute odontodes; spinelet short; spine long, adpressed distal tip slightly surpassing base of last branched dorsal-fin ray, posterior margin with weak-developed serrations. Pectoral-fin rays I,7(31); inner margin of pectoral spine with 20-27 well-developed serrations along its entire length. Outer margin of pectoral spine with one to five serrations located on distal portion in some specimens ( Fig. 3 ). Pelvic-fin rays i,5(31). Anal-fin rays i,6 (1), ii,4(4), or ii,5*(28). Caudal-fin rays i,12,i(31), generally three upper and lower procurrent rays, respectively. Cleithrum exposed on anteroventral portion; coracoid exposed on posterolateral portion; small odontodes sparse on exposed areas. Free vertebrae 22(3); ribs 5(3), first pair conspicuously large.

Two laterosensory canals on trunk; first ossicle tubular, second ossicle laminar. Body plates with minute odontodes scattered over exposed area, a conspicuous line of odontodes confined on posterior margins; dorsolateral body plates 23(2), 24*(22), or 25(9); ventrolateral body plates 20(3), 21*(18), or 22(12); dorsolateral body plates along dorsal-fin base 5(13), 6*(12), 7(4), or 8(2); dorsolateral body plates between adipose and caudal fins 8*(21), or 9(10); preadipose platelets 2*(12), 3(15), 4(4), or 5(1), adipose spine opposed to anal-fin insertion; small platelets covering base of caudalfin rays; small platelets disposed dorsally and ventrally between junctions of lateral plates on posterior portion of caudal peduncle.

Color in alcohol. Ground coloration of head yellowish lightbrown with entire top of the head dark brown. Small rounded or striated dark brown blotches scattered over dorsal and lateral areas of head and trunk. Diffuse dark stripe between corner of mouth and anterior margin of orbit. Opercle and preopercle with several, small, scattered dark brown chromatophores over their surfaces. Chromatophores more concentrated over anterior border of opercle. Irregular, darkbrown blotch on dorsal portion of opercle ( Fig. 4 ).

Ground color of trunk yellowish light brown. Cleithrum with rounded, dark-brown blotch on dorsal portion. Two or four elongated dark-brown blotches over junction of dorso- and ventrolateral body plates. Anterior blotch less conspicuous; posteriormost blotches just below adipose fin and on caudal-fin base, respectively.

Ground color of fins light yellow; interradial membranes hyaline. Dorsal-, pectoral- and caudal-fin rays with minute, scattered, elongated blotches. Pelvic- and anal- fin rays without spots. Small dark-brown areas on anterior margin of dorsal and adipose fins and caudal-fin base.

Distribution. Corydoras lymnades is known from upper and middle rio São Francisco basin, from headwater streams in the Minas Gerais State to the main channel of the river in the Bahia State, northeastern Brazil ( Fig. 5 ).

Etymology. The Lymnades are small creatures derived from the Goblins, according to Greek mythology. They live around lakes and have the task to protect the Nymphs from men that dare to try get close to them. The legend says that the Lymnades have the divine power of see in the bottom of a man’s soul and take the form of the most beloved person for the unwary that invade the territory of the nymphs. After deceiving the victims they kill and devour them. The new species is a close resemblance with Corydoras garbei , a similar look species considering its body coloration but with evidently larger individuals. The epithet lymnades makes allusion with the small size of the new species and its coloration similarity with C. garbei . A noun in apposition.

Identification key to the species of Corydoras from the rio São Francisco basin

1. Nuchal plate deeply in contact with posterior process of parietosupraoccipital by a small notch in the latter; snout relatively rounded ................................................................. 2

1’.Nuchal plate not in contact with posterior process of parietosupraoccipital; snout relatively pointed .............................................................................. C. difluviatilis

2. Body with a series of relatively large dark blotches along junction of body plates; first infraorbital very large, conspicuously expanded towards its anteroventral margin, and almost entirely covering lateral margin of the snout ( Fig. 2a ) ................................................................................... 3

2’. Body with small dark blotches scattered all over the flank and dorsum, not forming defined series; first infraorbital large, but not covering significantly the lateral margin of the snout ( Fig. 2b ) ..................................... C. multimaculatus

3. Dorsum with a series of longitudinal blotches, one on anterior origin of dorsal fin base, other on posterior origin of dorsal fin base, the third on the base of adipose fin and the last one on the base of caudal fin; rounded blotches on junction of lateral body plates; body deep (approximately 38.5% of SL) ..................................... C. garbei

3’. Dorsum with small rounded or striated blotches scattered over the aforementioned areas; oblong blotches on junction of lateral body plates; body slender (approximately 30.9% of SL) ...................................................................... C. lymnades

Figures

Fig. 1. Corydoras lymnades, holotype, MNRJ 40186, 29.7 mm SL, Brazil, Minas Gerais, Guarda-Mor, rio Guarda-Mor, rio São Francisco basin, 17°46’18”S 47°05’43”W. Dorsal, lateral and ventral views.

Fig. 2. Schematic drawing of the head of (a) Corydoras lymnades, (b) Corydoras flaveolus and (c) Corydoras difluviatilis in lateral view.Abbreviations: io1: infraorbital 1, io2: infraorbital 2, sph: sphenotic, cpt: compound pterotic.

Fig. 3. Pectoral-fin spine (7.1 mm) of Corydoras lymnades, NUP 9965, 28.0 mm SL, showing the serrations in inner margin of the right spine. The arrow indicates the serration in outer margin of the spine distal portion, present in some specimens.

Fig. 4. Schematic drawing showing color pattern details in anterior portion of the body of Corydoras lymnades, based in a paratype, NUP 9965, 28.7 mm SL.

Fig. 5. Map showing geographic distribution of Corydoras lymnades. Yellow star represents type locality, rio Guarda- Mor, Minas Gerais State. Each symbol may represent more than one locality.