Charax niger Lucena, 1989

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 : 215-217

Charax niger Lucena, 1989

Figs. 19-20

Charax niger Lucena, 1989: 99 [original description, type locality: Brazil, Amapá, rio Amapá (river channel), Cachoeira Grande ]. -Oyakawa, 1996: 455 (listed in catalog). - Lucena & Menezes, 2003: 201 (maximum length; distribution).

Diagnosis. Charax niger differs from C. caudimaculatus and C. notulatus in the orbital diameter (30.1-38.4% vs. 25-28.5% of HL, Fig. 4 ). Charax niger can be distinguished from C. caudimaculatus and C. notulatus in the scale rows around the caudal peduncle (17-18 vs. 20-22), from C. michaeli by the number of scale rows from the dorsal-fin origin to the lateral line (15-16 vs. 18-20), from C. pauciradiatus by the number of the scale rows from the dorsal-fin origin to the lateral line (15- 16 vs. 13-14), from C. gibbosus by the number of predorsal scales (52-68 vs. 38-45) and the absence (vs. presence) of ectopterygoid teeth) and from C. leticiae in having the humeral spot distance (35.4-37.8% of SL, Fig.3 , with 5-6 transverse scale rows in space from the humeral spot to the supracleithrum vs. the humeral spot distance, 38.5-44.8% of SL, with 8-10 transversal scale rows from the humeral spot to the supracleithrum). Charax niger 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 in having the anal-fin origin always anterior to the vertical through the dorsal-fin origin (vs. anal-fin origin on, or slightly posterior to, the vertical through the dorsal-fin origin) and ectopterygoid teeth absent (vs. ectopterygoid teeth present).

Description. Morphometrics of examined specimens presented in Table 11 . Body elongate, moderately large (40- 127 mm SL), compressed and moderately deep. Greatest body

from MZUSP 31137, 81137, 81266, 81193, 87354, 87355.

depth slightly in advance of dorsal-fin origin. Dorsal profile of head and body straight from tip of snout to anterior portion 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 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 to about vertical through posterior border of pupil.

Dorsal-fin rays ii, 9-10, 9, posteriormost ray unbranched. Adipose fin present. Unbranched anal-fin rays iv or v, usually iv, branched rays 44-52, 48.2. Sexually mature males with hooks on anal-fin ( Fig. 20); one male specimen (MZUSP 33424, 105 mm SL) with bilateral tiny hooks on posterior anterior 11 rays, number of hooks varying considerably, but posteriormost rays with fewer hooks: third unbranched ray with 28, fourth unbranched ray first branched ray with 22, second with 28, third with 19, fourth with 17, fifth with 17, sixth with 6, seventh with 7, eighth with 8, nineth with 9, tenth with 6, and eleventh with 3. Pectoral-fin rays i, 12-17, 14. Tips of longest pectoral-fin rays reaching slightly beyond middle of pelvic-fin length. Pelvic-fin rays i, 7. No hooks on pelvicfin rays of sexually mature males. Tips of longest pelvic-fin rays reaching vertical through bases of second and fourth branched anal-fin rays. Principal caudal-fin ray count 10/ 9 in all specimens.

Lateral line complete; perforated scales 53-60, 56.3. Horizontal scale rows from dorsal-fin origin to lateral 15-16, 15.7. Horizontal scale rows from pelvic-fin origin to lateral line 9-11, 9.8. Scale rows from anal-fin origin to lateral line 11-14, 12. Predorsal scales 52-68, 58. Scale rows around caudal peduncle 17-18, 17.8. Scale row along anal-fin base extending for about 2 /

3

of fin 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 9-16, 13. Maxillary teeth conical, 47-77, 67.2, larger specimens usually with higher counts. Dentary with one canine-like tooth followed by 3-6, 4.4 conical teeth, another canine-like tooth and a posterior row of 18-36, 28.2 conical teeth.

Gill-rakers on lower limb of first gill-arch 8-10, 8.4. 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 portions. Body lighter ventrally with scattered dark chromatophores especially posteriorly. Dorsal part of head, snout and tip of lower jaw darker than remainder of head; dark chromatophores spreading over first, second, fourth, fifth and sixth infraorbitals, between second and third infraorbitals as subocular blotch extending ventrally to ventral border of preopercle, median portion of

N. A. Menezes & C. A. S. de Lucena 217

lower jaw and median portion of maxilla. Scattered dark chromatophores on preopercle, and opercle. Irregularly shaped vertically elongate dark blotch at humeral blotch encompassing about 3 to 4 scales horizontally and 4 to 5 vertically. Triangular dark blotch on caudal base, dark chromatophores of posterocentral portion extending over bases of median caudal-fin rays. Darker lines of chromatophores along miosepta of epaxial muscles above lateral line and miosepta of hypaxial muscles below lateral line; more conspicuous on body region posterior to vertical through termination of dorsal-fin base, forming V-shaped patterns. All fins hyaline with scattered dark chromatophores more visible on the interradial membranes. Inconspicuous clear stripe dorsally below bases of anterior anal-fin rays, approaching and extending very close to anal-fin base from about middle to end of fin base. Anterior portion of first and second unbranched dorsal-fin rays and first unbranched rays of pectoral and pelvic fins darker than remaining rays.

Sexual dimorphism. Females lack tiny anal-fin hooks described above for males and usually reach on average larger body sizes than males. The only four males available (MZUSP 33430, MZUSP 33431, MZUSP 38303, and MZUSP 33424) have fully developed testes and anal-fin hooks respectively at 83.5, 104, 101, and 105 mm SL. Females with developed ovaries (MZUSP 33430, MZUSP 33431, MZUSP 33424, and MZUSP 3830) were fully mature at sizes between 103 and 127 mm SL. Distribution. Charax niger is known from rio Tocantins, rio Amapá and tributaries; rio Negro and tributaries; and a tributary of rio Preto da Eva, Brazil ( Fig. 7 ).

Specimens examined. Brazil, Amazonas: MZUSP 31137 , 1 , 70 mm SL, Anavilhanas, rio Negro , 3°06’53"S 60°00’14"W ; MZUSP 81137 , 1 , 79.3 mm SL, rio Tiquié, between communities Caruru and Boca de Sal , 0°16’N 69°54’W , rio Negro drainage ; MZUSP 81266 , 1 , 79.3 mm SL, community of Caruru, rio Tiquié, rio Negro drainage, 0°16’N 69°54’W ; MZUSP 81193 , 3 , 76-96 mm SL, community of Caruru, rio Tiquié, rio Negro drainage, 0°16’N 69°54"W; MZUSP 87354 , 1 , 40 mm SL, Recanto do Buriti, Rio Preto da Eva, rio Negro drainage, 2°41’58"S 59°54’W ; MZUSP 87355 , 1 , 95 mm SL, Rio Preto da Eva, igarapé Agripino, tributary of rio Preto da Eva , 2°43’59"S 59°40’48"W . MZUSP 33427 , 6 , 97-122 mm SL, Amapá, Cachoeira Grande , canal of river, not precisely located. Tocantins : UNT 9042 , 1 , 83 mm SL, riacho afluente do rio Santa Tereza, Sucupira , 12º15‘0"S 48º41’01"W ; UNT 166 , 2 , 62-68 mm SL , UNT 2563 , 1, 107 mm SL, Lagoa Pedra do Santo, Brejunho de Nazaré , 11º01‘S 48º34‘W .

Figures

Fig. 19. Charax niger, MZUSP 33427, female, paratype, 113 mm SL.

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

Fig. 3. Humeral spot distance as a function of standard 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.

Tables

Table 11. Morphometrics of Charax niger. Specimens are

Characters	Holotype	n	range	mean SD
Standard length	122.0	39	40.0 - 127.0 101.2
Percents of standard length
Depth at dorsal-fin origin	38.1	39	35.6 - 41.2	38.2	1.2
Snout to dorsal-fin origin	52.0	39	50.0 - 53.0	51.6	0.5
Snout to pectoral-fin origin	28.7	39	26.7 - 30.5	28.5	1.0
Snout to pelvic-fin origin	37.7	39	35.3 - 39.5	37.4	1.0
Snout to anal-fin origin	50.8	39	47.5 - 52.7	50.5	1.3
Caudal peduncle depth	8.6	39	7.5 - 9.2	8.4	0.4
Caudal peduncle length	7.8	39	6.4 - 9.5	7.5	0.5
Pectoral-fin length	20.1	38	18.2 - 22.0	20.0	0.7
Pelvic-fin length	21.3	38	18.4 - 23.1	21.1	1.0
Dorsal-fin base length	12.3	39	11.1 - 13.1	12.1	0.4
Dorsal-fin height	-	25	28.8 - 31.1	30.0	0.6
Anal-fin base length	50.0	39	46.3 - 53.0	50.0	1.4
Anal-fin lobe length	-	39	14.4 - 18.0	16.1	0.8
Eye to dorsal-fin origin	39.3	39	36.5 - 40.8	38.8	0.8
Dorsal-fin origin to caudal-fin base 55.7		39	54.2 - 57.1	55.3	1.0
Humeral spot distance	36.4	39	35.4 - 40.0	37.6	1.2
Bony head length	27.0	39	25.6 - 28.7	27.3	0.5
Percents of head length
Horizontal orbital diameter	33.3	39	30.8 - 35.5	32.8	0.8
Snout length	28.8	39	25.8 - 31.0	28.2	1.0
Least interorbital width	21.2	39	21.2 - 24.3	23.0	0.8
Upper jaw length	65.1	39	60.1 - 66.6	63.7	1.4