COMPLETE LARVAL DEVELOPMENT OF GALATHEA INTERMEDIA LILLJEBORG REARED IN LABORATORY CULTURE (ANOMURA: GALATHEIDAE)

Abstract

Larvae of East Atlantic anomuran crab Galathea intermedia Lilljeborg were reared in laboratory from hatching to juvenile stage. The larvae were kept in 3 l-32%o S sea water at 15°C. The complete larval development consists of 4 or 5 zoeal and 1 megalops stage. The larval are described and morphological characters are compared with those of West Atlantic species Galathea rostrata A. Milne Edwards described by Gore (1979). Galathea intermedia Lilljeborg, 1851, oc­ curs along eastern coasts of Atlantic from northern Norway (Christiansen, 1972) to Dakar (Zariquiey Alvarez, 1968). The species has also been reported from Angola, and it occurs in entire Mediterranean (Holthuis, 1961). It is most common in depths between 8 and 100 m (Holthuis, 1950). It is a very common species in all deeper parts of German Bight (North Sea), living in particularly high numbers be­ tween mollusc shells near island of Hel­ goland (Caspers, 1950). Its meroplanktonic were most abundant anomuran larvae in this area, occurring from June through October (Fiedler, 1987). The larvae of G. intermedia were dealt with by Sars in 1889. He described lar­ vae of three species of Galathea, G. in­ termedia, G. nexa Embleton, and G. squamifera Leach together, figuring certain stages, and only last larval and first postlarval of G. intermedia. Webb (1921) gave a short description of larval stages of genus Galathea based on four species G. dispersa Bate, G. intermedia, G. squamifera, and G. strigosa (Linnaeus) recorded in Plymouth Marine Invertebrate Fauna, with figures of first larval of G. squamifera, and telson and uropods of fourth larval of Galathea sp. Based on larvae hatched from eggs and larvae from plank­ ton, Lebour (1930, 1931) described larval of G. dispersa, G. strigosa, G. squam­ ifera, and G. intermedia and made a key of zoeal larvae of four species. Unfor­ tunately, descriptions and figures by Le­ bour are of limited value for identifying lar­ vae from plankton. Bull (1937) described and second zoeal of G. nexa and expanded Lebour's key to include larvae of all five British species of Galathea. Gurney (1939, 1942) referred to Sars' and Lebour's descriptions of larvae of G. inter­ media. Pike and Williamson (1972) made keys to zoeal and megalops of Galatheidae in which G. intermedia is included. The complete description of all larval of a species of Galathea was pub­ lished by Gore (1979), who cultured larvae of western North Atlantic species G. ros­ trata A. Milne Edwards in laboratory. As he pointed out, the lack of detailed de­ scriptions in earlier studies on galatheid lar­ val morphology prevents comparative statements to be made among most of species for which larvae are known. The present paper gives a complete descrip­ tion of all larval of a second species, G. intermedia. The larvae were reared from hatching to crab stage under labo­ ratory conditions, and their morphology is compared with that of G. rostrata.