Gymnocorymbus flaviolimai, Benine, Ricardo C., Melo, Bruno F., Castro, Ricardo M. C. & Oliveira, Claudio, 2015

Benine, Ricardo C., Melo, Bruno F., Castro, Ricardo M. C. & Oliveira, Claudio, 2015, Taxonomic revision and molecular phylogeny of Gymnocorymbus Eigenmann, 1908 (Teleostei, Characiformes, Characidae), Zootaxa 3956 (1), pp. 1-28 : 21-23

Gymnocorymbus flaviolimai , new species

Fig. 13 , Table 6

Gymnocorymbus thayeri, Queiroz et al. (2013) : 254–255.

Holotype. INPA 47805, 47.2 mm SL, Rio Guaporé, Costa Marques, Rondônia, 12°26’42.0”S 64°13’37.9”W, 21 Sep 1985, G. M. Santos.

Paratypes. Brazil, Rondônia, Porto Velho. UFRO-ICT 0 10141, 2, 1 c&s, 44.9–48.4 mm SL, cofferdam of cachoeira de Santo Antônio, Rio Madeira, 8°48’30.0”S 63°36’53.0”W, Aug 2009, Bios team. UFRO-ICT 13231, 5, 1 c&s, 41.4–51.5 mm SL, downstream cachoeira de Santo Antônio, 8°46’S 63°56’W, Aug 2009, Bios team. UFRO-ICT 0 20475, 2, 40.5–47.4 mm SL, foz do Rio Cautário, 12°10’58.1”S 64°34’59.8”W, 0 1 Sept 2012, LIP/ UNIR team. INPA 13258, 1, 37.3 mm SL, collected with holotype. INPA 13257, 1, 37.4 mm SL, Rio Guaporé, Costa Marques (Surpresa), 12°26’42.0”S 64°13’37.9”W 17 Jun 1984, G. M. Santos. INPA 11125, 2, 36.8–39.4 mm SL, Rio Madeira, Igarapé Xicanga, 24 Aug 1976. H. Axelrod. Guajará-Mirim. INPA 11098, 4, 43.7–48.7 mm SL, Rio Pacaás Novos, 10°56’58.0”W 65°20’21.8”S, 23 Jun 1984, G. M. Santos. UFRP-ICT 0 17650, 1, 50.9 mm SL, Rio Pacaás Novos, ca. 800 from its mouth, 10°51’38.7”S 65°16’20.6”W, 0 6 Sept 2012, A. Queiroz. UFRO-ICT 0 0 8409, 1, 40.2 mm SL, Rio Sotério, near to the confluence with Rio Mamoré, 11°35’00.0”S 65°13’00.0”W, 30 May 2010, L.H. Rapp Py-Daniel. UFRO-ICT 0 13510, 1, 41.9 mm SL, igarapé at the mouth of Rio Negro/Sotério, 11°36’36.6”S 65°11’10.6”W, 13 Jan 2012, T.R. Araújo. Peru: Madre de Dios: USNM 263955, 1, 44.5 mm SL, second stream entering Río Tambopata on SW shore, upstream of mouth of Río La Torre, 23 Aug 1983, R. P. Vari. USNM 264001, 3, 40.5–45.6 mm SL, Reserva Natural de Tambopata, Laguna Chica, end opposite boat dock (farthest from trail leading to lodge), 19 Aug 1983, R. P. Vari. Bolivia: USNM 305388, 3, 35.7–41.8 mm SL, Departamento Beni, Ballivia Province, small pond S of El Porvenir Biological Station entrance, 41 air km E of San Borja, Aug 1987, Starnes et al. . MZUSP 27819, 2, 30.6–33.1 mm SL, Rio Chapare, between Todos os Santos and its mouth, 26 Jun 1982, Convênio ORSTOM-UTB.

Diagnosis. Gymnocorymbus flaviolimai can be promptly distinguished from all congeners, except G. ternetzi , by having relatively smaller dentary and premaxillary teeth, with approximately one half the size of the length of those teeth ( Fig. 8 ). Gymnocorymbus flaviolimai differs from G. ternetzi by bearing premaxillary teeth with five cusps (vs. teeth with three cusps; Fig. 8 ) and further differs from G. bondi and G. thayeri by the strongly convex distal margin of the anal fin (vs. straight in G. bondi or slightly convex in G. thayeri ), and by having i,6 pelvic-fin rays (vs. i,7).

Description. Morphometric data for Gymnocorymbus flaviolimai is summarized in Table 6 . Body deep. Largest specimen examined 51.5 mm SL. Greatest depth at origin of dorsal fin. Dorsal profile of head slightly concave. Dorsal profile of body convex from posterior tip of supraoccipital to end of dorsal-fin base; slightly convex from rear of dorsal-fin base to end of adipose-fin base. Caudal peduncle profile slightly concave both dorsally and ventrally. Ventral profile of head and body convex from tip of lower jaw to caudal peduncle origin. Prepelvic region slightly keeled medially and flattened proximate to pelvic-fin insertion. Postpelvic median keel extending from pelvic-fin insertion to anal-fin origin.

Supraoccipital process elongate; tip extends beyond vertical through posterior margin of opercle.

Mouth terminal. Maxillar extending beyond vertical through anterior margin of orbit nearly to vertical through middle of orbit. Premaxillary teeth in two rows. Outer row with 2 (1), 4* (22) or 5 (1) tricuspidate teeth with central cusp longest. Inner tooth row with 6* (22) or 7 (2) pentacuspidate teeth with central cusp longest. Maxillar lacking teeth* (9) or with 1 (17) tricuspidate teeth. Dentary with 4 (1) or 5* (27) pentacuspidate teeth with central cusp usually longest, followed by one to three small teeth, with one or three cusps.

Dorsal-fin rays ii, 9*. Pectoral-fin rays i,10,i (13) or i,11,i* (9). Tip of pectoral fin extends beyond midlength of adpressed pelvic fin. Adipose fin present. Pelvic-fin rays i,6* (28). Tip of adpressed pelvic fin extends to first branched ray of anal fin. Anal-fin rays iv,36 (1), 37 (7), 38 (5), 39 (7), 40* (5), 41 (1). Caudal fin forked with i,17,i principal caudal-fin rays.

Scales cycloid. Lateral line complete with 32 (3), 33* (6), 34 (3), or 35 (2) scales. Scale rows between lateral line and dorsal-fin origin 7 (3) or 8* (15). Scale rows between lateral line and pelvic-fin origin 7 (1), 8* (19), or 9 (1). Circumpeduncular scale rows 12* (5) or 13 (3). Scale sheath along anal-fin base in 5–6 series extending along length of anal-fin base.

First gill arch with 9 (2) or 10* (8) on upper limb and 14 (8) or 15* (3) on lower limb. Total vertebrae in radiographs 32 (1 specimen, INPA 11098), 33 (3 specimens, INPA 11098; 1 specimen, INPA 13258), or 34* (holotype; 2 specimens, INPA 11125). Supraneurals 4.

Color in alcohol. Overall coloration yellow tan. Homogeneous field of scattered dark chromatophores covers posterior half of body. Dark chromatophores more densely concentrated along dorsal midline. Dense field of dark chromatophores over both lips, and dorsal third of maxilla. Infraorbital and opercular series guanine. Dark vertical stripe as wide as pupil crossing orbit. Two conspicuous vertical dark humeral marks. Anterior mark narrower than posterior mark. Anterior humeral mark located over second to fourth lateral line scales and extending over five horizontal scale rows above lateral line and four to five scale rows below lateral line. Posterior humeral mark located over ninth to twelfth lateral line scales and extending over six horizontal scale rows above lateral line and four to five horizontal scale rows below lateral line. Dorsal half of both humeral marks wider and more densely pigmented. Dorsal and anal fins homogeneously dark pigmented. Paired fins and caudal fin with few scattered dark chromatophores, more so on unbranched rays. Adipose fin densely dark pigmented, more so along its dorsal border ( Fig. 13 ).

Sexual dimorphism. Mature males bear a pair of small hooks per segment on posterior branch of first five to eight branched anal-fin rays.

Distribution. Gymnocorymbus flaviolimai is presently known from the Rio Madeira of the Amazon basin in Bolivia, Brazil and Peru.

Etymology. The specific epithet flaviolimai is after Dr. Flávio César Thadeo de Lima, a dear friend, for his contribution to our knowledge on the Neotropical ichthyology.

Figures

FIGURE 8. Anterior view of a premaxillary tooth of (a) Gymnocorymbus flaviolimai, INPA 11098, 46.7 mm SL, relatively smaller, pentacuspidate tooth; (b) G. ternetzi, LIRP 367, 37.7 mm SL, tricuspidate tooth; and (c) G. thayeri, LBP 17756, 40.2 mm SL, relatively larger, pentacuspidate tooth. Scale bar = 0.25 mm.

FIGURE 13. Gymnocorymbus flaviolimai, INPA 47805, holotype, 48.7 mm SL, Rio Guaporé, Rio Madeira, Costa Marques, Rondônia, Brazil.

Tables

TABLE 6. Morphometric data for Gymnocorymbus flaviolimai; N includes holotype.

	N Holotype	Paratypes limits	Mean
Standard length (mm)	30 47.2	30.6–51.5	–
Percentage of standard length
Greatest depth	30 63.8	49.2–61.7	57.9
Snout to dorsal-fin origin	30 56.4	51.9–57.7	55.1
Snout to pectoral-fin origin	22 30.4	32.2–33.5	32.6
Snout to pelvic-fin origin	30 50.2	48.0–54.5	50.1
Snout to anal-fin origin	22 65.1	62.3–67.8	65.7
Caudal peduncle depth	30 10.4	8.2–10.9	9.5
Caudal peduncle length	22 8.3	5.6–9.3	7.1
Pectoral-fin length	30 26.5	23.4–30.4	26.4
Pelvic-fin length	30 17.2	13.8–19.9	17.6
Dorsal- fin length	27 35.6	26.5–40.2	35.4
Dorsal-fin base	30 16.9	16.0–19.9	18.0
Anal-fin length	30 25.2	19.9–35.4	26.9
Anal-fin base	30 49.2	46.3–53.6	49.9
Eye to dorsal fin origin	22 43.8	39.6–43.8	41.7
Dorsal fin origin to caudal fin origin	22 57.8	53.0–57.8	55.4
Head length	30 28.0	28.0–34.5	30.2
Head depth	30 21.0	20.6–34.6	26.5
Percentage of head length
Snout length	30 29.5	21.7–29.5	25.0
Upper jaw length	22 46.6	40.6–46.3	43.1
Horizontal orbital diameter	30 12.1	10.2–14.8	12.7
Least interorbital width	30 35.6	37.9–36.2	31.8