Characidium kamakan, Zanata & Camelier, 2015

Zanata, Angela M. & Camelier, Priscila, 2015, Two new species of Characidium Reinhardt (Characiformes: Crenuchidae) from northeastern Brazilian coastal drainages, Neotropical Ichthyology (Neotrop. Ichthyol.) 13 (3), pp. 487-498 : 488-491

Characidium kamakan , new species u r n:l s i d:z o o b a n k.o rg:a c t: 3 D2E D 4 0E -3 3 0 2-4 9 5 3 -8 2D 0- 9F3B1B3E822C

Fig. 1

Holotype. MZUSP 115000 , 51.9 mm SL, Brazil, Bahia, Camacan, rio Panelão on the road between Camacan and Jacareci, rio Pardo basin, 15°25’16”S 39°31’48”W, 162 m above sea level, 15 Sep 2013, A. M. Zanata, T. Ramos, L. Oliveira & T. Duarte.

Paratypes. All from Brazil, Bahia, rio Pardo basin . UFBA 7563 , 5 , 38.7-46.2 mm SL, collected with holotype . MNRJ 42132 , 6 , 39.8-47.2 mm SL , MZUSP 115008 , 6 , 34.7-53.7 mm SL , UFBA 5679 , 14 , 1 c&s, 29.6-55.3 mm SL, same locality as holotype, 4 Nov 2009, A. M. Zanata, P. Camelier & R. Burger ; MZUSP 112697 , 3 , 42.6-52.6 mm SL, same locality as holotype, 11 Ago 2012, O . T. Oyakawa, A. M. Zanata, P. Camelier & T. F. Teixeira . UFBA 6531 , 7 , 32.6- 54.3 mm SL, Camacan, rio Panelão, near the entrance to the Reserva Particular de Patrimônio Natural Serra Bonita , 15°22’46.1”S 39°32’34.5”W, 184 m above sea level, 2 Nov 2009, A. M. Zanata, P. Camelier & R. Burger . UFBA 7565 , 1 , 47.1 mm SL, same locality as UFBA 6531, 16 Sep 2013, A. M. Zanata , T. Ramos, L. Oliveira & T. Duarte . UFBA 7564 , 11 , 35.1-53.1 mm SL, Pau Brasil, rio Água Preta, 1 km from Pau Brasil, 15°25’51.1”S 39°39’34.4”W, 173 m above sea level, 16 Sep 2013, A. M. Zanata , T. Ramos, L. Oliveira & T. Duarte .

Diagnosis. Characidium kamakan can be readily distinguished from all congeners by its unique color pattern, with distinct black borders of scales forming short vertical traces on body. The new species is further distinguished from other congeners, except C. alipioi Travassos, C. boavistae Steindachner, C. crandellii Steindachner, C. declivirostre Steindachner , C. gomesi Travassos , C. grajahuensis Travassos , C. japuhybense Travassos , C. lauroi Travassos, C. macrolepidotum (Peters), C. oiticicai Travassos , C. pterostictum Gomes, C. schubarti Travassos, C. timbuiense Travassos , C. vidali Travassos , and members of the C. fasciatum Reinhardt clade, by lacking scales on isthmus. Characidium kamakan further differs from these congeners by the absence of conspicuous vertically elongated bars or blotches on body (vs. presence in C. alipioi , C. declivirostre , C. fasciatum , C. gomesi , C. grajahuensis , C. lauroi , C. oiticicai , C. timbuiense , and C. vidali ), presence of a conspicuous black blotch at midlength of caudal-fin rays shaped like a 3 and unpigmented rounded areas close to the base of the lobes (vs. two or more dark bars on caudal fin and/or absence of rounded clear areas at the base of caudal-fin lobes in C. gomesi , C. grajahuensis , C. japuhybense , C. lauroi , C. oiticicai , C. pterostictum , C. schubarti, and C.timbuiense ), having only the anteriormost portion of isthmus naked (vs. naked area broader, from isthmus to the vertical through contralateral bases of last pectoral-fin ray in C. macrolepidotum; from isthmus to median area of belly in C. crandellii and C. declivirostre ), and presence of small foramen for the ophthalmic nerve bordered by a well-developed bony crest (vs. exceptionally large pterosphenoid foramen for the ophthalmic nerve, not usually bordered by bony crests in C. boavistae). More specifically, from congeners known to occur in rivers draining northeastern Brazil, C. kamakan further differs by having all fins with conspicuous dark bars or blotches (vs. absence of blotches on fins, except by an inconspicuous dark bar crossing dorsal-fin midlength of C. bahiense , C. deludens new species, and C. samurai , or a well-marked dark bar at base of dorsal-fin rays and a second faded bar at distal portion of fin in C. bimaculatum ).

Description. Morphometric data for holotype and paratypes presented in Table 1. Body fusiform and moderately compressed. Greatest body depth at vertical through dorsal-fin origin. Dorsal profile convex from upper lip to vertical through nares, slightly convex from this point to end of occipital process, slightly convex or straight from this point to dorsal-fin base origin, slightly convex or straight along dorsal-fin base, straight between end of dorsal-fin base and adipose fin, and slightly concave from this point to origin of anteriormost dorsal procurrent caudal-fin ray. Ventral profile straight along length of head, slightly convex from isthmus to pelvic-fin origin, straight from latter point to origin of anal fin, and slightly concave from this point to origin of anteriormost ventral procurrent caudal-fin ray. Snout triangular-shaped from lateral view. Mouth subterminal, aligned with or slightly lower than ventral edge of orbit. Distal tip of maxilla barely reaching anterior margin of orbit. Orbit rounded, approximately with same length as snout. Cheek thin, its depth about a third of orbit diameter. Nares separated, both with skin flaps and raised margins; posterior naris closer to eye than to anterior naris. Supraorbital somewhat drop-shaped in dorsal view, medial margin convex abutting frontal and lateral margin straight to slightly concave, anterior portion directed away from frontal bone, somewhat wider than posterior portion. Parietal fontanel limited anteriorly by parietals. Parietal branch of supraorbital canal present, not trespassing frontal-parietal border. Orbithosfenoid slightly rectangular in lateral view, connected anteriorly to rhinosphenoid. Pterosphenoid foramen for ophthalmic nerve relatively small, formed by a tunnel crossing diagonally pterosphenoid and bordered by bony crest preventing direct lateral view of brain cavity through foramen.

Dentary teeth in two rows; outer series with 7(9), 8*(12), 9(8), or 10(4) teeth; anterior teeth tricuspid, posterior conical; teeth decreasing in size from symphysis; inner series, with several minute conical teeth inserted on edge of replacement tooth trench. Premaxilla with single series of 5(2), 6*(19), or 7(14) tricuspid teeth, decreasing in size from symphysis; lateral cusps very small, central somewhat elongate. Maxillary edentulous. Ectopterygoid teeth 20(1), conical, in a patch of two or three somewhat disorganized series. Mesopterygoid teeth absent.

Scales cycloid; circulii absent on posterior field of scales located immediately below 10 th scale of lateral line, 17 to 20 radii present. Lateral line complete, pored scales 33(5), 34*(27), or 35(3); horizontal rows of scales above lateral line 3*(32) or 4(3); horizontal rows of scales below lateral line 3*(14) or 4(20). Scales along middorsal line between supraoccipital and origin of dorsal fin 9*(15), 10(11), or11(1) in single row or irregularly arranged(6). Scales rows around caudal peduncle 12(7), 13(11), or 14*(16); some specimens with scale rows somewhat irregularly arranged. Axillary scale absent. Isthmus naked on its anterior portion; naked portion not reaching pectoral-fin area. Pseudotympanum present, represented by muscular hiatus at vertical through anterior portion of swim bladder; most of hiatus situated between ribs of fifth and sixth vertebrae, but with small opening anterior to rib of 5 th vertebra ( Fig. 2a ).

Dorsal-fin rays ii,9*(36); distal margin of dorsal fin somewhat rounded. Adipose fin present. Pectoral-fin rays highly variable iii,7,ii(2), iii,8,i(24), iii,8,ii(5), iii,9(7), iii,9,i(8), iii,10*(2), iv,8,i(2), iv,9,i(1), or v,8,i(1), with 3 rd and 4 th branched pectoral-fin rays longest; posterior tip of pectoral fin usually reaching pelvic-fin insertion. Pelvic-fin rays ii,5,i(1), i,6,i(1), ii,6,i(2), i,7,i(26), ii,7*(4), or i,8(2), with 3 rd or 4 th branched pelvic-fin rays longest; posterior tip of pelvic fin not reaching anal-fin origin. Anal-fin rays ii,5(2) or ii,6*(34); posterior margin of anal fin straight, slightly rounded, or somewhat pointed in some mature males. Caudal-fin rays i,9,8,i*(30). Dorsal procurrent caudal-fin rays 7(1); ventral procurrent caudal-fin rays 6(1).

Total number of vertebrae 34(1); precaudal vertebrae 16(1); caudal vertebrae 18(1). Supraneural bones 5(1), 1 anterior to neural spine of 5 th centrum. Epural bones 2(1). Uroneural bones 1(1). Branchiostegal rays 4(1); 3 connected to anterior ceratohyal, 1 connected to area between anterior and posterior ceratohyal.

Color in alcohol. Ground color of head and body whitish to pale yellow ( Fig. 1 ). Dark stripe from snout tip to anterior margin of orbit. Dark blotch posterior to orbit usually separated from it by narrow clear area; some specimens with blotch forming stripe aligned with that of snout, although somewhat broader. Opercle dark, mainly in its dorsal half. Dark irregular blotches on head dorsum. Area around nares somewhat clear. Ventral half of head clear, with sparse small melanophores. Scales with melanophores densely concentrated along posterior margin, forming short vertical black traces; some specimens with dark borders of scales aligned, forming traces somewhat longer; few scales on lateral surface of body without concentration of melanophores, resulting in small clear areas. Dark midlateral stripe inconspicuous, formed by underlying dark pigment, extending from rear of head to caudal peduncle. Dark humeral blotch on rear of opercle usually inconspicuous, merged with longitudinal band. Nine or 10 inconspicuous dark vertical bars formed by underlying pigment on lateral surface of body, usually more visible on area over longitudinal stripe; some specimens without vertical bars. Ventral portion of body yellowish; area anterior to pelvic fins usually without concentration of melanophores on scale margins, area posterior to pelvic fins with borders of scales dark. All fins with dark pigmentation pattern. Dorsal-fin base with a dark bar formed by melanophores over rays and interradial membranes, broader anteriorly; second dark bar around midlength of rays, usually broad anteriorly over two or three branched rays, divided into two bands posteriorly; or, in some specimens, continuous throughout fin, without division; distal borders of rays usually dark. Caudal fin with conspicuous 3-shaped black blotch covering basal portion of four or five median caudal-fin rays black and midlength of lobes; area of lobes anterior to blotch completely clear; distal margins of caudal-fin rays somewhat dark. Some specimens with 3-shaped blotch somewhat inconspicuous due to extra short dark traces on posterior half of fin. Pectoral fin with concentration of melanophores at dorsal portion of rays, usually more evident on distal half. Pelvic fin with dark bar over midlength of rays. Anal fin with similar dark bar, primarily at midlength of rays. Central portion or posterior half of adipose fin usually darkly colored.

Color in life. Dark pattern on scales and fins similar to that of specimens in alcohol. Ground color of body and fins yellow or orange; dorsal and caudal-fins strongly pigmented, particularly with yellow marks at base of caudal-fin lobes. Lateral of head silvery.

Sexual dimorphism. No hooks were observed on fins of the specimens examined. Mature males (around 50.0 mm SL) have the 3 rd and 4 th branched pelvic-fin rays somewhat longer than in females of similar standard length, reaching closer to anal-fin origin when adpressed. Furthermore, in some mature males the posterior border of the anal fin is somewhat more pointed due to the elongation of some branched rays (especially the 2 nd), while in females the branched anal-fin rays usually have similar lengths and straight or rounded fin border. However, a more detailed analysis of a greater number of mature specimens is necessary for a precise evaluation of the dimorphic features described above.

Distribution. Characidium kamakan was sampled in the rio Água Preta and rio Panelão, tributaries of the lower portion of rio Pardo basin, Bahia State, Brazil ( Fig. 3 ).

Habitat and ecological notes. The rio Pardo is an eastern coastal drainage with its upper and part of middle portions located in the state of Minas Gerais and its lower portion in the state of Bahia, within the domain of the Atlantic Forest. The new species occurs in the latter area and was captured in stretches of the rio Água Preta and rio Panelão ( Fig. 4 ), at altitudes ranging from 162-184 m above sea level, with moderate to rapid water current, running over rock, pebbles and sand bottoms, 0.3-1.5 m deep, with rapids, pools, and meanders. Locally, the riparian vegetation has shrubs, trees, and grass. The surrounding original Atlantic Forest had been converted to cocoa plantations and more recently to cattle ranches, coffee, and rubber crops. Characidium kamakan inhabits places with fast water current over substrate composed of medium to somewhat large sized stones. The analysis of stomach contents of two specimens revealed the presence of allochthonous and autochthonous items, composed by fragments of vascular plants, organic debris, insect larvae ( Diptera : Chironomidae and other unidentified orders), and fragments of unidentified arthropods.

Etymology. Named after the Kamakã indigenous people that originally inhabited the area. A noun in apposition.

Conservation status. Characidium kamakan is so far known from localities in the lower rio Pardo basin, with a relatively restricted distribution. The species occurs in rapid water stretches within domain originally covered by the Atlantic Forest, posteriorly converted to cocoa plantations and more recently to cattle ranches, coffee, and rubber crops. However, since no imminent threats to the species were detected C. kamakan could be classified as east Concern (LC) according to the International Union for Conservation of Nature (IUCN) categories and criteria ( IUCN Standards and Petitions Subcommittee, 2014). Additional collecting efforts should be conducted in that region in order to better understand biological aspects and distribution of the species.

Figures

Fig. 1. Characidium kamakan, holotype, MZUSP 115000, 51.9 mm SL, Brazil, Bahia, Camacan, rio Panelão, tributary of lower rio Pardo basin.

Fig. 2. Pseudotympanum of (a) Characidium kamakan, paratype, UFBA 5679, 45.7 mm SL, and (b) C. deludens, paratype, UFBA 3850, 41.9 mm SL. Number corresponds to the pleural rib of the 5th vertebra. Left side, anterior to left. Overlying skin, adipose tissue, and lateral-line nerve removed.

Fig. 3. Map of distribution of Characidium kamakan (black and white symbols) and C. deludens (red symbols) in middle and lower rio Pardo basin and upper rio Paraguaçu basin, respectively, Bahia State, northeastern Brazil; type localities indicated by stars.

Fig. 4. Type locality of Characidium kamakan, Bahia, Camacan, rio Panelão, lower rio Pardo basin.