Charax delimai Menezes & de Lucena 2014, new species

Charax delimai, new species

Fig. 10

Holotype. MZUSP 81505, male, 100 mm SL, Brazil, Amazonas, community of São Pedro, rio Tiquié, rio Negro drainage, 0°16’04"N 69°58’21"W, 2004, Adão A. Barbosa.

Paratypes. Brazil, Amazonas: MZUSP 84988, mature female, 102 mm SL, near old community of São Pedro, 0°16’04.4"N 69°58’21.5"W, 2004, F. Lima; MZUSP 64359, mature female, 121 mm SL, igarapé Umari, tributary of rio Tiquié in community of São Pedro, 0°15’41"N 69°57’23"W, 25-27 October 2000, F. C. T. Lima and party; MZUSP 81325, male, 102 mm SL, igarapé Umari, tributary of rio Tiquié in community of São Pedro, 0°16’00"N 69°58’00"W, 2002, F. C. T. Lima and party.

Diagnosis. Charax delimai along with C. tectifer, C. metae and some specimens of C. gibbosus, C. rupununi and C. condei are the only members of the genus bearing teeth on the ectopterygoid. Charax delimai differs from C. condei in having the lateral line complete (vs. incomplete). From Charax gibbosus and C. rupununi which have the anal-fin origin anterior to the vertical through the dorsal-fin origin in having the anal-fin origin on vertical or slightly posterior to, dorsalfin origin. Charax delimai can be readily distinguished from C. tectifer by the presence (vs. absence) of superficial neuromasts on body, with neuromasts dorso-ventrally arranged on trunk scales except those on the lateral line where neuromasts are absent (Fig. 1) and from C. metae by having fewer ectopterygoid teeth (3-15 vs. 20-50), more transverse scale rows between the humeral spot and the supracleithrum (10-12 vs. 7-9) and the humeral spot distance 48-51% of SL (vs. 41.6-47% of SL, Fig. 3).

Description. Morphometrics of holotype and all examined specimens presented in Table 4. Body elongate, moderately large (100-121 mm SL), compressed and moderately deep. Greatest body depth slightly in advance of dorsal-fin origin. Dorsal profile of head and body convex from tip of snout to anterior part of fontanel, concave from that point to base of supraoccipital spine, convex from that point to dorsal-fin origin, nearly straight along dorsal-fin base and from end of dorsal-fin base to caudal peduncle and slightly concave along caudal peduncle. Ventral profile of head and body convex from tip of lower jaw to anal-fin origin, nearly straight along anal-fin base and slightly concave from end of anal-fin base to beginning of procurrent rays. Snout pointed. Lower jaw included in upper jaw when mouth closed. Maxilla extending slightly beyond vertical through middle of orbit.

Dorsal-fin rays ii, 9 in all specimens posterior most ray unbranched. Adipose fin present. Unbranched anal-fin rays iv or v, usually iv; branched rays 41-45 (iv, 45), 41.9.Anterior anal-fin rays not forming differentiated distinct lobe and not bearing bilateral hooks in two adult males (100 and 102 mm SL). Pectoral-fin rays i, 13-15 (i, 14), 14.5. Tips of longest pectoral-fin rays reaching about to vertical through middle of pelvic fin. Pelvic-fin rays i, 7. No hooks on pelvic-fin rays of adult males. Tips of longest pelvic-fin rays reaching slightly beyond anal-fin origin. Principal caudal-fin ray count 10/ 9 in all specimens.

Lateral line complete, perforated scales 50-53 (52), 51. Horizontal scale rows from dorsal-fin origin to lateral line 11- 12 (12), 11.7. Horizontal scale rows from pelvic-fin origin to lateral line 9-10 (9), 9.2. Horizontal scale rows from anal-fin origin to lateral line 11-12 (12), 11.7. Predorsal scales 33-35 (34). Scale rows around caudal peduncle 19-20 (20), 19.5. One scale row along anal-fin base, except on last one-fifth of its length. Rostral portions of body scales of both males and females, except for lateral-line scales with vertically oriented superficial neuromasts (Fig. 1).

Premaxillary with one anterior canine-like tooth followed by set of smaller conical teeth and another canine-like tooth followed by one or two small conical teeth. Total number of premaxillary teeth 13-17 (14) 14.7. Maxillary teeth conical, 55-56 (55), 55.2. Dentary with one canine-like tooth followed by 3-5 (4) 4 conical teeth, another canine-like tooth and posterior row of 21-24 (24) 23 conical teeth. Left ectopterygoid without teeth or with 3 or 9 teeths; right ectopterygoid with 6-9 conical teeth. Total number of ectopterygoid teeth 3-15 (9), 9. Vertebrae 34- 35 (34), 34.2. Eight gill-rakers on lower limb of first gill-arch in all specimens. Branchiostegal rays 4; 3 rays originating from anterior ceratohyal and 1 from posterior ceratohyal

Color in alcohol. Body pale to light yellow, slightly darker dorsally than ventrally due to concentration of dark chromatophores on predorsal and postdorsal scales. Dark chromatophores mostly concentrated on basal portions of scales leaving light area on remaining portion of each scale and forming alternate pattern of dark and light spots along longitudinal scale rows on body. Whitish color of vertically arranged superficial neuromasts on skin of basal portion of each scale and contrasting strongly with background dark coloration of basal portion of scale (Fig. 1). Scales on lateral and ventral body portions with fewer chromatophores. Irregularly shaped dark humeral blotch, much closer to dorsalfin origin than to posterior border of opercle, encompassing about 5 scales vertically and horizontally. Dark blotch on caudal peduncle approximately triangular, higher posteriorly and extending over basal portions of central caudal-fin rays. Dorsal portions of head from tip of snout to supraoccipital region darker than remainder of head, dark color extending vertically over first, second, and anterior portion of third infraorbitals below orbit, dorsal portion of prepercle and inner border of opercle. Most of third, fourth and fifth infraorbitals, ventral portion of preopercle, posterior border of opercle and subopercle largely unpigmented with scattered dark chromatophores. Tip of lower jaw dark; lighter posteriorly with scattered chromatophores. Tip of dorsal fin dark. Anal fin with faint basal dark stripe extending from about basal portion of first branched anal-fin ray to end of fin, this stripe separated by light anteriorly wide stripe involving basal and median portions of unbranched rays, narrower from this point backward. Conspicuous dark wider marginal dark stripe extending to end of fins, initially separated by small light stripe extending only to about tenth branched anal-fin ray. Tip of pelvic fin dark, pectorals light with few scattered dark chromatophores. Marginal portion of caudal fin dark, all fin with scattered dark chromatophores.

Sexual dimorphism. Males of this species much darker than females and both sexes possess superficial neuromasts vertically arranged along basal portions of each scale albeit less numerous on females (Fig. 1).

Etymology. Charax delimai is named after Flávio César Thadeu de Lima for his great contributions to the knowledge of neotropical freshwater fishes and for collecting most of the specimens that served as the basis for the species description.

Distribution. Charax delimai is known from the rio Tiquié, rio Negro basin, Brazil (Fig. 7).