PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 1 13(l):54-65. 2000. Larval development of Cryptolithodes expansus Miers (Decapoda: Anomura: Lithodidae) reared in the laboratory Mi Hyang Kim and Sung Yun Hong Department of Marine Biology, Pukyong National University, Pusan 608-737, Korea E-mail: [email protected] Abs tract. — The complete larval development of Cryptolithodes expansus Miers is described based on laboratory rearing. The species has four zoeal stages and a megalopa. The larvae are described and illustrated, and detailed comparisons are made with other lithodid larvae, particularly those of Cryp-tolithodes typicus Brandt. Cryptolithodes expansus Miers, 1879 is found along the Korean coast (personal ob-servation) and in Japan (Makarov 1938, 1962) on rocky bottoms in the sublittoral region to a depth of about 50-60 m. The family Lithodidae is represented by 16 gen-era and 95 species (Dawson 1989), but the larval development of only 16 species, rep-resenting 9 genera, has been described (Konishi 1986; Haynes 1984, 1993; Koni-shi & Taishaku 1994). Sars (1890) described all zoeal stages up to the megalopa of Lithodes maja Linnaeus, 1758. Subsequent studies of Lithodidae lar-vae have been described, at least in part, for 15 species (Konishi 1986; Haynes 1984, 1993; Konishi & Taishaku 1994): Crypto-lithodes typicus Brandt, 1848, Dermaturus mandtii Brandt, 1850, Hapalogaster greb-nitzkii Schalfeew, 1892, H. dentata (De Haan 1844), H. mertensii Brandt, 1850, Lithodes aequispina Benedict, 1895, L. an-tarctica Jacquinot, 1853, Lopholithodes mandtii Brandt, 1848, Paralithodes brevi-pes (H. Milne Edwards & Lucas, 1841), P. camtschaticus (Tilesius 1815), P. platypus (Brandt 1850), Paralomis granulosa (Jac-quinot 1852), P. hystrix (De Haan 1846), Placetron wosnessenskii Schalfeew, 1892, and Rhinolithodes wonessenskii Brandt, 1848. Hart (1965) described all zoeal stages, megalopa and crab 1 stage of Cryptolitho-des typicus Brandt, 1848 reared in the lab-oratory. This is the only species of Cryp-tolithodes for which larvae are known so far. The purpose of the present study is to describe complete larval stages of C. ex-pansus reared in the laboratory, and to com-pare them with those of C. typicus. Materials and Methods On 20 August 1995 a local fisherman caught three berried females of Cryptolitho-des expansus with a commercial octopus trap in the vicinity of Pusan (35°10'N, 129°10'E), Korea. The ovigerous females were brought to the laboratory, and kept in a container filled with running sea-water. On 10 March 1996, about 250 larvae hatched from one of the females. Of these, 60 were individually reared in 50 ml glass bottles placed in an incubator at 9.5-10.5°C. Some larvae were kept in 11 glass beakers for mass culture. Larvae were fed with newly hatched Ar-temia nauplii. Moulting and mortality were checked daily. After checking, the larvae were transferred to freshly prepared bottles and beakers. At each developmental stage, dead larvae and exuviae were fixed and pre-served with 3% neutralized formalin solu-tion. At least five specimens of each stage were dissected in ethylene glycol for mi-croscopic observation. Drawings were made with the aid of a drawing tube.