First record of partial melanism in the coney Cephalopholis fulva (Perciformes: Epinephelidae)

Abstract

raphaelmacieira@hotmail.com Many abnormalities in the coloration of fishes have been recorded, including albinism, melanism and ambicoloration (e.g . DAHLBERG, 1970). Melanism, according to Gould and Pyle (1896), is characterized by the presence of an excessive amount of pigment in tissues and skin. In fishes, melanism may occur in varying degrees of intensity (PIGG, 1998) and can, in some cases, result from injury (DAHLBERG, 1970), genetic inheritance (HORTH, 2006), intergeneric hybridization (ELWIN, 1957) or parasite infestation (HSIAO, 1941). The coney Cephalopholis fulva (Linnaeus, 1758) is distributed in the Western Atlantic from South Carolina, USA, to Southeastern Brazil (FIGUEIREDO; MENEZES, 1980). As its Northwestern Atlantic and Caribbean counterparts, the Brazilian coney presents three color phases. The red phase is found in deep water individuals, the uniformly brown or bicolored phase (in which the upper half of the body is dark brown and the lower half creamy white) is mostly encountered in shallow water individuals and the xanthic phase (actually a morph rather than a phase) is found independently of depth (SMITH, 1971). This author suspected that the yellow variety is actually the result of a single gene, but no further information exists on this subject. The species exhibits diel changes in the pattern of coloration and the alternation between the fully brown pattern in daytime and the bicolored pattern at night has been fully documented (NEMTZOV et al., 1993). This present study describes the first recorded occurrence (DAWSON, 1964, 1966, 1971) of partial melanism in the coney. The specimen was captured about 10 km off the coast of Guarapari, Espirito Santo, Southeastern Brazil, near Rasas and Escalvada islands (20o42’07,8”S e 40o23’36,8”W), during hook and line samplings undertaken at quarterly intervals between July 2005 and October 2007. The substrate is formed of a mosaic of calcareous algae beds, rocky and biogenic reefs and extensive deposits of unconsolidated sediments, at depths varying from 15 to 33 m. An additional 147 coneys were captured during sampling. None, however, presented any type of coloration abnormality. The frequency of occurrence of the anomaly was therefore estimated to be 0.68 %. The specimen was photographed still fresh (Fig. 1a) and maintained frozen until fixation in 10 % formaldehyde and preservation in 70 % ethanol. The area of the melanic part of the body was estimated from a digital photography of the right side of the fish (Fig. 1a). A 1300-square grid was digitally overlaid onto the photography to determine the proportion of squares over melanic skin. As both sides displayed the some pattern and extent of melanosis, there was no need for measuring the area on the left side, and the result obtained for the right side was extrapolated for the whole body. The specimen is deposited in the fish collection of the Universidade Federal do Espirito Santo (CIUFES 0219). The anomalous specimen is an individual of medium size (223 mm total length; 186 mm standard length) and apparently healthy. The melanic portion is restricted to the posterior half of the body, beginning at a vertical under the last spine of the dorsal fin and extending to the end of the tail. This corresponds to 37.7 % of the corporal surface area (fins included). The excess of melanin was limited to the epidermis over the posterior extremity of body scales and over the whole scales and naked skin on the fins. The intensity of the pigmentation of the melanic area is greater on the dorsal and caudal fins, merging into a blander tonality in the lateral region of the body. The two small black spots on the top of the caudal peduncle, usual in this species (HEEMSTRA; RANDALL, 1993), cannot be seen due to the strong pigmentation in this region. The remainder of the body displays the normal coloration of an individual in the red phase (HEEMSTRA; RANDALL, 1993). In particular, the small dark-edged pale blue spots over the whole body (observed in the fresh organism (Fig. 1a) but that turned entirely dark after fixation (Fig. 1b) and the two small black spots on the tip of the lower jaw (one on each side), characteristic of the species, are present.