LARVAL DEVELOPMENT OF GALATHEA ROSTRATA UNDER 



LABORATORY CONDITIONS, WITH A DISCUSSION OF 



LARVAL DEVELOPMENT IN THE GALATHEIDAE (CRUSTACEA ANOMURA)^ 



Robert H. Gore^ 



ABSTRACT 



The complete larval development of the western Atlantic anomuran crab, Galathea rostrata, consists of 

 four or five zoeal stages, and a single megalopal stage, based on larvae cultured under laboratory 

 conditions. Variation in the duration and number of zoeal stages appears to be temperature-dependent, 

 with larvae reared at 15°C developing through five zoeal stages and attaining megalopa in 52 days, 

 whereas larvae cultured at 20°C passed through four or five zoeal stages, reaching megalopa in 18 or 23 

 days, respectively. At 20°C some third stage zoeae molted to a "regular" fourth zoeal stage, without 

 pleopods, which was followed by a subsequent fifth stage before reaching megalopa. Other zoeae molted 

 to an "advanced" fourth stage, possessing pleopods, which subsequently molted directly to megalopa, 

 bypassing stage V completely. The variation noted in larval development in other galatheid genera is 

 briefly discussed, and a provisional s3Tiopsis of morphological characters of systematic value is pro- 

 vided for their identification. 



The anomuran crab genus Galathea is presently 

 represented in the western North Atlantic by two 

 species, G. agassizii andG. rostrata (A. Milne Ed- 

 wards 1880). Galathea agassizii, primarily tropi- 

 cal and insular in distribution, is a deepwater 

 species known from 166 to 490 fm (304-897 m) off 

 St. Augustine, Fla., and from Cuba, St. Vincent, St. 

 Lucia, and Barbados in the Caribbean Sea. In the 

 eastern Atlantic the species is found from 82 to 898 

 fm (150-1,643 m) in the vicinity of both the Cape 

 Verde and Canary Islands, and off northwestern 

 Africa (Chace 1942; Miyake and Baba 1970). 

 Contrarily, G. rostrata appears to be a warm- 

 temperate or tropical/subtropical species, primar- 

 ily continental in distribution. The species is re- 

 corded from the North American continental shelf 

 at Cape Hatteras, N.C., to southeastern Florida, 

 and in the Gulf of Mexico from western Florida, 

 the Mississippi Delta, and southward to Islas Jol- 

 bos, north of the Yucatan Peninsula. There is a 

 questionable record from off Rhode Island (Wil- 

 liams 1965). Galathea rostrata is also found in 

 shallower water than G. agassizii and has been 

 collected from 10 to 50 fm (18-92 m), with the 

 exception of the possible depth record of 1,178 fm 



'Scientific Contribution No. 100, from the Smithsonian 

 Institution-Harbor Branch Foundation, Inc., Scientific Consor- 

 tium, Link Port, Ft. Pierce, Fla. This report is Article IX. 

 Studies on Decapod Crustacea from the Indian River Region of 

 Florida. 



^Smithsonian Institution, Ft. Pierce Bureau, Ft. Pierce, FL 

 33450. 



Manuscript accepted June 1978. 



FISHERY BULLETIN: VOL. 76, NO. 4, 1979. 



(2,156 m) from off Rhode Island. The only distribu- 

 tional record of the species for the entire eastern 

 Florida coast was that of Haig (1956) who reported 

 a single specimen collected from 21 fm (38 m) off 

 Hillsboro Lighthouse (Broward County) in south- 

 eastern Florida. However, recent collections show 

 that the species is not uncommon in the Indian 

 River region of the central eastern Florida coast, 

 especially on deeper water (60+ m) coquinoid 

 limestone ledges and reefs of the ivory tree coral, 

 Oculina varicosa Leseuer. 



The few studies made on the larval development 

 of new world galatheid crabs (e.g., Rayner 1935; 

 Boyd 1960; Fagetti 1960; Boyd and Johnson 1963; 

 Fagetti and Campodonico 1971) have all been 

 made on eastern Pacific species, and the larvae of 

 Atlantic American galatheids, including the 

 genus Galathea, remain undescribed. 



This paper provides the first description and 

 illustration of the complete larval development of 

 G. rostrata, as well as the first report on any 

 species of Galathea reared totally under labora- 

 tory conditions, from hatching to megalopal stage. 

 The larvae and postlarvae are compared with lar- 

 val stages known from other members of the 

 Galatheidea throughout the world, and shared 

 features are briefly summarized. 



MATERIALS AND METHODS 



Eight ovigerous females of G. rostrata were ob- 

 tained on 15 April 1977 by lockout diver from the 



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