Charax stenopterus (Cope, 1894)

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 : 222-223

Charax stenopterus (Cope, 1894)

Fig. 25

Asiphonichthys stenopterus Cope, 1894: 67 (original description, type locality: Brazil, Rio Grande do Sul State, headwaters of rio Jacuí ). -Böhlke, 1984: 54 (listed in type catalog).

Charax stenopterus, Lucena, 1987: 26 (diagnosis; description; comparisons; distribution; geographic variation; morphometric data). -Lucena, 1989: 104 (in key to species). -Lucena & Menezes, 2003: 201 (maximum length; distribution). -López et al., 2003: 17 ( Argentina, listed). - Casciotta et al., 2003: 83 (Laguna Iberiá, Argentina, listed). -Menni, 2004: 74 ( Argentina, listed).

Diagnosis. Charax stenopterus is distinguished from congeners except C. condei and C. hemigrammus by having the lateral line incomplete and the dorsal part of the body anterior to the dorsal fin without scales (vs. lateral line complete and the dorsal part of body anterior to dorsal fin with scales). Charax stenopterus differs from C. hemigrammus in the number of scale rows from the pelvic-fin origin to the lateral line (7-9 vs. 11-12) and from C. condei in lacking ectopterygoid teeth and 18-28 teeth on the posterior dentary row (vs. ectopterygoid teeth present and 30-41 teeth on the posterior dentary row).

Description. Morphometrics of examined specimens presented in Table 14. Body elongate, moderately large compared to congeners (33-85 mm SL), compressed and comparatively low. Greatest body depth slightly in advance of dorsal-fin origin. Dorsal profile of head and body slightly convex from tip of snout to anterior region of fontanel, slightly 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 very slightly concave along caudal peduncle. Ventral profile of head and body convex from tip of lower jaw to anal-fin origin, nearly straight to slightly concave 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 to about vertical through middle of orbit.

Dorsal-fin rays ii, 8-10, 9, posteriormost ray unbranched. Adipose fin present. Unbranched anal-fin rays iv or v, usually iv, branched rays 37-48, 43.2. No hooks on anterior anal-fin rays of all examined mature males. Pectoral-fin rays i, 11-17, 14. Tips of longest pectoral-fin rays extending slightly beyond vertical through middle of pelvic-fin length. Pelvic-fin rays i, 7. No hooks on pelvic-fin rays of all examined mature males. Tips of longest pelvic-fin rays reaching vertical through bases of second and fourth branched anal-fin rays. Principal caudalfin ray count 10/ 9 in all specimens.

Lateral line incomplete; perforated scales 2-10, 6. Lateral series scales 40-47, 43.4. Horizontal scale rows from pelvic-fin origin to lateral line 7-9, 8.1. Scale rows around caudal peduncle 16-18, 16.7. No scale rows anteriorly along anal-fin base.

Premaxillary with one anterior large conical tooth followed by set of smaller conical teeth, one to two large conical teeth and 1-4 smaller conical teeth. Total number of premaxillary teeth 10-17, 13. Maxillary teeth conical, 37-52, 42.6; larger specimens generally with higher counts. Dentary with anterior row including 4-7, 5.2 conical teeth and posterior row with 18- 28, 21.1 conical teeth.

Vertebrae 31-33, 32.1. Gill-rakers on lower limb of first gillarch 7-10, 8.3. Branchiostegal rays 4, 3 rays originating from anterior cerathyal and 1 from posterior ceratohyal.

Color in alcohol. Body pale, with scattered dark chromatophores more concentrated on dorsal part of head and dorsal and lateral portions of trunk, extending over snout, maxillae, tip of jaws, and infraorbitals, less so ventrally. Dark humeral blotch inconspicuous to well-developed; blotch extending about two scales horizontally and one scale vertically. Concentration of dark chromatophores on caudalfin base forming tringular-shaped blotch with chromatophores on posterocentral portion extending onto bases of central caudal-fin rays. Chromatophores darker slightly above midbody, forming V-shaped lines along miosepta of epaxial and hypaxial musculature; lines more conspicuous on posterior portion of body. All fins hyaline with scattered dark chromatophores, especially abundant on interradial membranes of dorsal, anal, and basal portion of caudal fins; fewer chromatophores on pectoral and pelvic fins.

Distribution. This species is widely distributed in tributaries of rio Jacuí and coastal lagoons of Rio Grande do Sul, Brazil and Uruguay. It occurs also in tributaries of the rio Uruguay, Brazil and lower rio Paraná, Brazil, Paraguay, and Argentina ( Fig. 7 ).

Specimens examined. Brazil: Rio Grande do Sul. MZUSP 9616 , 4 , 52.5 -67.0 mm SL, Pelotas , lagoa dos Patos, 31°46’S 52°20"W; MZUSP 14182 , 1 , 85 mm SL, Osório, lagoa dos Quadros, 29°43"S 50°07’W ; MZUSP 4499 , 4 , 58-70 mm SL, São Leopoldo, Porto do Vicente, rio dos Sinos, rio Jacuí drainage, 29°45"S 51°10"W ; MZUSP 19884 , 1 , 69 mm SL, near Porto Alegre, arroio in município de Belém Novo, 30°12"S 51°12"W ; MZUSP 19919 , 1 , 75 mm SL, Marquês de Souza, rio Forqueta, rio Jacuí drainage, 29°20"S 52°05"W ; MZUSP 19975 , 1 , 51 mm SL, Estação Ecológica do Taim , lagoa Mirim, stream near fazenda Caçapava, 32°29S , 52°35"W; MZUSP 19968 , 1 , 64 mm SL, near Arroio Grande, on road between Pelotas and Jaguarão , 32°14’S 53°05"W ; MZUSP 19726 , 2 , 44-46 mm SL, São Leopoldo, rio dos Sinos, rio Jacuí drainage, 29°45’S 51°10’W ; MZUSP 19730 , 2 , 45-46 mm SL, Pelotas, rio Pelotas near bridge, 31°37’S 52°19"W; MZUSP 19683 , 3 , 43-46 mm SL, Montenegro , Vapor Velho, 27°47’45"W ; MZUSP 19734 , 4 , 33-40 mm SL, km 124 on road BR- 116, between Schailan and Montenegro , near arroio Preto. Uruguay : MZUSP 19375 , 3 , 69-83 mm SL, arroyo Toledo .

Figures

Fig. 25. Charax stenopterus, MZUSP 19919, male, 75 mm SL, Brazil, Rio Grande do Sul, Marquês de Souza, rio Forqueta, rio Jacuí drainage.

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.