Charax apurensis Lucena, 1987

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 : 197-198

Charax apurensis Lucena, 1987

Fig. 6

Charax apurensis Lucena, 1987: 30 (original description, type locality: Venezuela, Estado Apure, road San Fernando to Cunaviche, río el Canito); - Vari & Howe, 1991: 13 (listed in type catalog). -Provenzano et al., 1998: 5 (listed in type catalog). - Lucena, 1987: 30 (diagnosis; description; comparisons; distribution; etimology). - Lucena, 1989: 104 (in key to species). - Lucena & Menezes, 2003: 201 (maximum length; distribution).

Diagnosis. Charax apurensis is included to the group of Charax species with relatively larger orbital diameters (30.1- 38.4% of head length, Fig. 4 ) that can be distinguished from C. caudimaculatus and C. notulatus that have smaller orbital diameters (25-28.5% of head length). Among the species having larger orbital diameters, C. apurensis differs from C. michaeli , C. pauciradiatus , C. gibbosus , C. niger , and C. leticiae , except C. macrolepis by having 20-21 (vs. 16-19) scale rows around the caudal peduncle. Charax apurensis differs from C. macrolepis by having 54-62 perforated scales along the lateral line (vs. 63-65). It can be distinguished from C. hemigrammus , C. condei , and C. stenopterus by having the lateral line complete (vs. lateral line incomplete), and from C. rupununi by the number of scales around the caudal peduncle (21 vs. 12). Charax apurensis differs 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. analfin origin on the vertical, or slightly posterior to, the dorsalfin origin) and ectopterygoid teeth absent (vs. ectopterygoid teeth present).

Description. Morphometrics of examined specimens presented in Table 1 . Body elongate, moderately large compared to congeners (68-104 mm SL), compressed and moderately deep. Greatest body depth slightly in advance of dorsal-fin origin. Dorsal head with body profile slightly convex on tip of snout, straight from posterior border of posterior nostril to vertical 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 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 posterior border of orbit.

Dorsal-fin rays ii, 8-9, 8.9; posteriormost ray unbranched. Adipose fin present. Unbranched anal-fin rays iv, branched rays 41-50, 46.5. Pectoral-fin rays i,13-15, 14. Tips of longest pectoral-fin rays almost reaching vertical through anal-fin origin. Pelvic-fin rays i,7. Longest pelvicfin rays reaching slightly beyond anal-fin origin in mature females 93 and 104 mm SL. Principal caudal-fin ray count 10/ 9 in all specimens.

Lateral line complete; perforated scales 54-62, 58.8. Horizontal scale rows from dorsal-fin origin to lateral line 19- 20, 19.5. Horizontal scale rows from pelvic-fin origin to lateral lateral line 11-12, 11.2. Horizontal scale rows from anal-fin origin to lateral line 14-19, 16.2. Predorsal scales 55-70, 62.2. Scale rows around caudal peduncle 21 in all specimens. One scale row extending on both sides for about ¾ of anal-fin base slightly beyond middle of anal-fin base.

Premaxillary with one anterior canine-like tooth followed by a set of smaller conical teeth and another canine-like tooth followed by one or two small conical teeth. Total number of premaxillary teeth 12-14, 13. Maxillary teeth conical, 62-70, 65.5, larger specimens in general with higher counts. Dentary with one canine-like tooth followed by 4- 6, 4.5 conical teeth, another canine-like tooth and a posterior row of 27-34, 29.2 conical teeth. Vertebrae 33 and 34 in two specimens. Seven to 9, 8.3 gill-rakers on lower limb of first gill-arch. 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 due to more dense concentration of dark chromatophores.Ventral portion of body lighter with scattered dark chromatophores especially anteriorly. Irregularly shaped dark blotch at humeral region encompassing 5 scales of longitudinal rows and 4 scales of transverse rows. Dorsal part of head, snout and tip of lower jaw darker than remaining portions of head. Dark coloration extending to anterior upper portion of maxilla and first, second and left marginal portion of third infraorbitals. Opercle with scattered dark chromatophores. Faint dark stripe extending from posterodorsal part of humeral blotch to caudal base enlarged posteriorly in form of caudal blotch not extending to base of caudal-fin rays. Pectoral and pelvic fins hyaline with scattered dark chromatophores. Dorsal, caudal and anal fins hyaline with dark chromatophores especially concentrated on interradial membranes.

Distribution. Charax apurensis is known from tributaries of río Orinoco, Venezuela ( Fig. 7 )

Specimens examined. Venezuela: MZUSP 27947 , 2 , 63-93 mm SL, Guarico, lagoons W of Caño Falcón, not precisely located ; MZUSP 40699 , 1 , 69 mm SL, Apure, estación Marisela, Caño Marisela, approximately 11 km from road San Fernando de Apure to Puerto Páez , not precisely located ; MZUSP 27890 , 1, 104 mm SL, Delta Amacuro, stream Guargapo, tributary of río Orinoco , approximately 8°51’N 61°26’W .

Figures

Fig. 6. Charax apurensis, MZUSP 110669, female, 104 mm SL.

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

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.