LARVAL DEVELOPMENT OF HYPOCONCHA SABULOSA 

 (DECAPODA: DROMIIDAE)' 



William H. Lang' and Alan M. Young' 



ABSTRACT 



Larval development of the dromiid crab, Hypoconcha sabutosa, consists of three zoeal stages and one 

 megalopa. The zoea exhibit numerous characteristics normally associated with anomuran larvae. 



Hypoconcha sabulosa (Herbst) is a relatively un- 

 common inhabitant of coastal waters from North 

 Carolina to the coast of Texas. Another member of 

 the genus,//, arcuata Stimpson, coexists through- 

 out much of the range (Williams 1965). These 

 crabs are frequently overlooked owing to their 

 habit of carrying an empty clam shell on their 

 back. Kircher (1970) described the laboratory- 

 reared larval stages of H. arcuata the larval 

 stages of//, sabulosa are undescribed. 



The family Dromiidae is an enigmatic group 

 which has remained a point of contention in the 

 phylogeny of the Decapoda. It has often been 

 suggested that the brachyurans are a monophyle- 

 tic group and that the dromiids represent a primi- 

 tive true crab (Balss and Gruner 1961; Glaessner 

 1969; Stevcic 1974; Warner 1977). However, it is 

 also strongly argued that the brachyurans are 

 polyphyletic and that the dromiids are more 

 closely related to anomuran or thalassinid groups 

 (Gumey 1942; Williamson 1974). 



METHODS 



On 14 June 1976, a single gravid H. sabulosa 

 female was collected by dredging in the North 

 Inlet estuary, near Georgetown, S.C. Water tem- 

 perature at the time of collection was 24" C; salin- 

 ity was 27%o. The female was returned to the 

 Baruch Laboratory, Columbia, S.C, and placed in 

 a 9 cm Carolina culture dish containing filtered 

 natural sea water of 25%o salinity and maintained 



'Contribution No. 287 from Belle W. Baruch Institute for 

 Marine Biology and Coastal Research, Columbia, SC 29208 



^Belle W. Baruch Institute for Marine Biology and Coastal 

 Research, Columbia, S.C; present address; U.S. Environmental 

 Protection Agency, Environmental Research Laboratory, South 

 Ferry Road, Narragansett, Rl 02882. 



^Belle W. Baruch Institute for Marine Biology and Coastal 

 Research, (Columbia. S.C; present address: Biology Department, 

 Nasson College, Springvale, ME 04083. 



at 25° C under a 14L:10D light schedule. On 21 

 June, the brood began hatching and 22 active lar- 

 vae were placed individually in 6 cm dishes con- 

 taining 15 ml filtered seawater (25%o) and main- 

 tained as described for the adult. Water was 

 changed daily and freshly hatched brine shrimp 

 nauplii (San Francisco Bay Brand'') were added as 

 food following each water change. Additional lar- 

 vae hatching during the following day were reared 

 in a 1 1 shallow glass dish under similar condi- 

 tions. These larvae were sacrificed during de- 

 velopment to provide replicate material for de- 

 scriptions. 



Records were kept for each of the 22 larvae indi- 

 vidually cultured to determine the number and 

 duration of larval stages. Exuviae and larvae were 

 preserved in 70% ethyl alcohol. Drawings were 

 made from preserved larvae using a Zeiss drawing 

 tube. Measurements of preserved larvae were 

 made with an ocular micrometer; total length and 

 carapace length are as defined by Pike and Wil- 

 liamson (1960a). Abbreviations and setal types 

 mentioned are as in Johns and Lang (1977). De- 

 scriptions and sizes are based on at least five ap- 

 parently healthy larvae sacrificed at each stage. 



RESULTS 



Development 



Three zoeal stages and a megalopa were ob- 

 tained through laboratory rearing; no variability 

 in the number of larval molts was observed. Lar- 

 vae were easily reared in both mass culture and 

 individual chambers. Of larvae not sacrificed, 72% 

 survived to megalopa and 75% of the megalopae 

 successfully molted to first crab (Table 1). 



Manuscript accepted June 1979 



FISHERY BULLETIN VOL 77, NO, 4. 1980. 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



851 



