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INTRODUCTION
Albinism is a hereditary lack of pigmentation caused by an enzyme deficiency involving the metabolism of melanin during prenatal development. It may involve the entire body or a part of the body (Boncinelli, 1998). A new term, known as 'leucism', has also been introduced to animal biology to describe reptiles and amphibians with abnormal skin pigmentation and normal eye colour (Bechtel, 1995) and recently it has also been used in ichthyology (Clark, 2002).
This phenomenon has been commonly reported in teleosts (Follett & Dempster, 1976; Dingerkus et al., 1991; Béarez, 2002) and also occurs among Chondrichthyes. In fact, partial or total albinism has been described in different species of cartilaginous fish, both rays (Traquair, 1893; Wilson, 1951; Schwartz, 1959; Joseph, 1961; Capapé & Pantoustier, 1975; Schwartz & Safrit Jr, 1977; Jesus-Roldand, 1990; Ben Braihim et al., 1998), and sharks (Herald et al., 1960; McKenzie, 1970; Gopolan, 1971; Cohen, 1973; Nakaya, 1973; Talent, 1973; Frøiland, 1975; Follet, 1976; Furuta, 1985; Taniuchi & Yanagisawa, 1987; McKay & Beinssen, 1988; Smale & Heemstra, 1997; Clark, 2002; Ferreira Teixeira & Góes de Araújo, 2002; Deynat, 2003).
The present note reports the occurrence of albinism in the kitefin shark Dalatias licha (Elasmobranchii, Dalatidae), a deep-water shark distributed on continental and insular shelves and slopes in warm temperate and tropical areas, from 40 to 1800 m (Compagno, 1984). In the Mediterranean, D. licha is mainly found in the western basin, where it is considered a relatively common component of the deep water elasmobranch fauna (Matallanas, 1982), and Italian waters (Tortonese, 1956; Bini, 1967). The colour of a normal kitefin shark can be dark grey-brown to black (Compagno, 1984).
MATERIALS AND METHODS
In January 2003, one specimen of Dalatias licha was caught by a professional bottom trawler operating in the bathyal grounds, ranging 450-800 m, off Genoa (Ligurian Sea). After landing it was frozen at -30°C. In the laboratory, the specimen was identified according to Compagno (1984), photographed and examined for total length (TL), total weight (TW) and sex. Morphometric and meristic characteristics were also collected following the keys of Compagno (1984) and compared with those of normal specimens of the same sex and equivalent length, caught within the same area. Stomach contents were...