Charax gibbosus (Linnaeus, 1758)

Menezes, Naércio A. & de Lucena, Carlos Alberto S., 2014, A taxonomic review of the species of Charax Scopoli, 1777 (Teleostei: Characidae: Characinae) with description of a new species from the rio Negro bearing superficial neuromasts on body scales, Amazon basin, Brazil, Neotropical Ichthyology 12 (2), pp. 193-228 : 204-206

Charax gibbosus (Linnaeus, 1758)

Figs. 11 and 12

Salmo gibbosus Linnaeus, 1758: 311 [type locality: Suriname; Wheeler, 1989: 208 (type information)].

Characinus gibbosus, Lacépède, 1803: 269 (diagnosis).

Epicyrtus gibbosus, Müller & Troschel, 1844: 346 (America meridionali; listed).

Cynopotamus gibbosus, Valenciennes, 1850: 321 (Mana River; Essequibo River; Amazon). -Lucena & Menezes, 2003: 201 [synonym of Charax gibbosus (Linnaeus, 1758) ].

Charax gibbosus, Lucena, 1987: 36 (diagnosis; description; geographic variation). -Lucena, 1989: 104 (in key to species). -Lucena & Menezes, 2003: 201 (maximim length; distribution).

Charax gibbosa, Eigenmann, 1910: 444 (Guianas, Amazons and Paraguay; listed).

Diagnosis. Charax gibbosus belongs in a species group having orbital diameter 30.1-38.4% of HL as opposed to C. caudimaculatus and C. notulatus that have an orbital diameter 25-28.5% of HL ( Fig. 4 ). Charax gibbosus differs from C. condei by having the lateral line complete (vs. incomplete). From C. and C. rupununi which have the anal-fin origin anterior to the vertical through the dorsal-fin origin in having the anal-fin origin posterior to the dorsal-fin origin. Charax delimai can be readily distinguished from C. tectifer by the presence ( Fig. 1 ) (vs. absence, Fig. 26 ) of superficial neuromasts on the body with neuromasts dorso-vantrally arranged on trunk scales except the lateral line and from C. metae by having fewer ectopterygoid teeth (13-15 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 the SL vs. 41.6-47% of the SL scale rows around the caudal peduncle (17-18) than C. apurensis and C. macrolepis (20-21), from C. michaeli by the number of scale rows from dorsal-fin origin to lateral line (15-16 vs. 18-20), from C. pauciradiatus by having more scale rows from the dorsal-fin origin to the lateral line (15-16 vs. 13-14), from C. leticiae by the humeral spot distance (34.7-37.5% of SL, vs. 38-44% of SL, the number of transverse scale rows between the humeral spot and the supracleithrum (5-6, vs. 8-10), and from C. niger by the number of predorsal scales (38-45 vs. 52- 68) and the presence (vs. absence) of ectopterygoid teeth. Charax gibbosus differs from C. hemigrammus , C. condei , and C. stenopterus by having the lateral line complete (vs. lateral line incomplete), from C. rupununi by the number of scales around the caudal peduncle (17-18 vs. 12) and from C. tectifer , C. metae , and C. delimai by having the anal-fin origin always anterior to the vertical through the dorsal-fin origin (vs. anal-fin origin along vertical or slightly posterior to vertical through the dorsal-fin origin) and the ectopterygoid teeth absent (vs. ectopterygoid teeth present).

Description. Morphometrics of examined specimens presented in Table 5. Body elongate, moderately large (34- 125.5 mm SL), compressed and moderately deep; greatest body depth slightly in advance of dorsal-fin origin. Dorsal profile of head an body slightly convex on tip of snout, straight from posterior border of posterior nostril to vertical line through posterior border of pupil, slightly concave from that point to base of supraoccipital spine, strongly 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 heaf and body convex from tip of lower jaw to anal-fin origin, nearly straight along anal-fin base and 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 posterior border of pupil.

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 45-56, 49.5. Single examined sexually mature male (MZUSP 10675, 64 mm SL) with tiny hooks on anterior anal-fin rays ( Fig. 12). Pectoral-fin rays i, 12-17, 14.8. Tips of longest pectoral-fin rays reaching to or slightly beyond middle of pelvic-fin length. Pelvic-fin rays i, 7, without hooks in single sexually mature male examined. Tips of longest pelvic-fin rays reaching to vertical between bases of third to sixth branched anal-fin rays. Principal caudalfin ray count 10/ 9 in all specimens.

Lateral line complete; perforated scales 50-62, 56. Horizontal scale rows from dorsal-fin origin to lateral line 15- 16, 15.4. Horizontal scale rows from pelvic-fin origin to lateral line 10-12, 10.8. Horizontal scale rows from anal-fin origin to lateral line 9-14, 11.8. Predorsal scales 38-45, 42. Scale rows around caudal peduncle 17-18, 17.8. One scale row anteriorly along anal-fin base, extending to about middle of base.

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 11-16, 13. Maxillary teeth conical, 43-75, 59.2, larger specimens in general with higher counts. Dentary with one canine-like tooth followed by 2-5, 4 conical teeth, another canine-like tooth and posterior row of 20-31, 25.3 conical teeth.

Vertebrae 34-35, 34.5 (4). Gill-rakers on lower limb of first gill-arch 9-11, 9.7. 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 on lateral and ventral parts. Ventral portions of body lighter with scattered dark chromatophores especially anteriorly. Irregularly shaped vertically elongate dark blotch at humeral region about 4 scales horizontally and 3 to 4 scales vertically. Dorsal portion of head, snout and tip of lower jaw darker than remainder of head, dark coloration extending to median portion of lower jaw, dorsal portions of fifth and sixth infraorbitals, between second and third infraorbitals in young specimens and dorsal part of opercle. Inconspicuous, dark midlateral stripe extending from posterior border of humeral blotch to caudal blotch. Darker V-shaped lines of chromatophores over miosepta present along lateral stripe. Inconspicuous diamond shaped dark blotch on caudal base, more conspicuous in young specimens; dark chromatophores extending over bases of middle caudal-fin rays.All fins hyaline with scattered dark chromatophores more visible on interradial membranes. Anterior portion of first and second unbranched rays of dorsal and first unbranched rays of pectoral- and pelvic-fin rays darker than remaining rays.

Distribution. This species is known from the Nickerie, Brokopondo, Afobaka, and Courentyne Districts in Suriname; Wismar and Botanical Garden in Guyana; and rio Surumu, a tributary of rio Branco, Brazil ( Fig. 7 ).

Sexual dimorphism. Females lack the anal-fin hooks present in males and seem to grow larger. The single examined fully mature male is only 64 mm SL whereas examined sexually mature females ranged from 75-124.5 mm SL.

206 Taxonomic review of Charax

Specimens examined. Suriname: MZUSP 38226 , 1 , 84 mm SL , Suriname, Corantyne River, Matappi Creek , approximately 4°07’N 57°28’W ; MZUSP 38240 , 5 , 34-57 mm SL , Suriname, Nickerie District, Kapoeri Creek, about 4 km N of intersection with Corantyne River , approximately 4°12’N 57°55’W ; MZUSP 10679 , 3 , 93-111 mm SL , Suriname, Zy Creek, not precisely located; MZUSP 10674 , 3 , 70-124.5 mm SL, Sara Creek, Brokopondo District, not precisely located; MZUSP 10675 , 2 , 37 and 64 mm SL, Marowijne Creek, 50 kilometers south of Afobaka , not precisely located . Brazil: MZUSP 5164 , 1 , 57 mm SL, Roraima, rio Surumu, tributary of rio Branco , 4°05’28"N 60°43’04"W .

Figures

Fig. 11. Charax gibbosus MZUSP 10674, female, 124.5 mm SL, Suriname, Sara Creek, Brokopondo District.

Fig. 4. Orbital diameter as a function of head length for species of Charax.

Fig. 1. Superficial neuromasts (black arrows) on lateral body scales of Charax delimai, male (a), MZUSP 81325, paratype, 102 mm SL, Brazil, Amazonas, igarapé Umari, tributary of rio Tiquié in community of São Pedro and female, (b), MZUSP 84988, paratype, 102 mm SL, Brazil, Amazonas, near old community of São Pedro.

Fig. 26. Charax tectifer, MUSM 38670, male, 85 mm SL, Peru, Satipo, río Tambo, Quebrada Pukakunga.

Fig.7. Map of SouthAmerica showing the collecting sites of the Charax species, and the type locality of Charax delimai (purple circle). Charax apurensis - yellow square; C. caudimaculatus - white circle; C. condei - white square; C. gibbosus - purple triangle; C. hemigrammus - red star; C. leticiae - black circle;C. macrolepis-black triangle;C.metae-yellow triangle;C.michaeli - yellow circle;C.niger -blue triangle; C.notulatus - blue circle; C. pauciradiatus - red triangle; C. rupununi - red circle; C. stenopterus - green triangle; C. tectifer - green circle. Some symbols may represent more than one locality.