THE COMPLETE LARVAL DEVELOPMENT IN THE LABORATORY OF 



MICROPANOPE SCULPTIPES {CRUSTACEA, DECAPODA, XANTHIDAE) 



WITH A COMPARISON OF LARVAL CHARACTERS IN 



WESTERN ATLANTIC XANTHID GENERA » 



Bryan L. Andryszak'' and Robert H. Gore^ 



ABSTRACT 



The larval development in the laboratory of Micropanope sculptipes, a western Atlantic deepwater 

 xanthid crab which inhabits encrusted and coralline substrates, is completely described and illus- 

 trated. Development proceeds from a prezoeal stage of brief duration through four zoeal stages and one 

 megalopa stage. Survival of larvae was poor under experimental conditions of diel illumination, 36%o 

 salinity, and temperatures of 20°, 25°, and 25°-30° C. Development to megalopa occurred only at 25° C. 

 Morphological characteristics of M. sculptipes zoeae and megalopa are compared with larval charac- 

 teristics of several other western Atlantic xanthid species. 



Crabs of the family Xanthidae are both numerous 

 and diverse with species inhabiting a great variety 

 of marine and estuarine environments (Rathbun 

 1930). The genus Micropanope was erected by 

 Stimpson in 1871 with the type-species Mi- 

 cropanope sculptipes. This genus consists of small 

 (12 mm carapace width) xanthid crabs with a 

 known range from the Bahamas and Florida Keys 

 to Brazil and Bermuda in deeper offshore oceanic 

 water (Rathbun 1930; Guinot 1967). Micropanope 

 was originally noted to resemble Pilumnus , and to 

 be allied with Panopeus , but was supposedly dis- 

 tinct in being a sublittoral to bathyal group and 

 not littoral as was Panopeus. However, subsequent 

 collections yielded Micropanope species which 

 were more littoral in distribution and, through 

 time, the genus was considered to be a heteroge- 

 neous mixture of several distinct generic groups 

 which were yet to be defined (Guinot 1967). This 

 author emended the genus Micropanope to contain 

 only two western Atlantic species: viz. M. 

 sculptipes Stimpson, the type-species, and M. 

 lohifrons A. Milne Edwards. The remaining 

 species within Micropanope sensu lato have either 



been placed by Guinot in several other genera, or 

 await placement in genera yet to be named. 



Larvae of many species of xanthid crabs from 

 several different genera have been described 

 based on laboratory rearing, but there have been 

 no published descriptions of a complete larval de- 

 velopment for any species of Micropanope sensu 

 lato thus far. A study on the larval development of 

 M. barbadensis Rathbun has recently been com- 

 pleted (Gore et al. 1981), but this species will ulti- 

 mately be assigned to a separate, and as yet un- 

 defined, genus close to Coralliope (fide Guinot 

 1967). A knowledge of the larval morphology of 

 Micropanope , when compared with larval charac- 

 teristics of previously described xanthid species, 

 especially those species once placed in the genus 

 Micropanope , may be of some utility in recognizing 

 the evolutionary relationships among such 

 species within the Xanthidae. Accordingly, in this 

 report we describe the complete larval develop- 

 ment of M. sculptipes from hatching to megalopa 

 stage based on specimens raised in the laboratory, 

 and compare these larval and postlarval stages 

 with those from other xanthid crabs in the western 

 North Atlantic. 



'Scientific Contribution No. 064, from the Smithsonian 

 Institution, Fort Pierce Bureau, Fort Pierce, Fla. This report 

 is Article XXI. Studies on Decapod Crustacea from the Indian 

 River Region of Florida. 



^Smithsonian Institution, Fort Pierce Bureau, Fort Pierce, 

 Fla.; present address: TerEco Corporation, 500 University West, 

 PO. Drawer GF, College Station, TX 77840. 



^Smithsonian Institution, Fort Pierce Bureau, Fort Pierce, 

 FL 33450. 



MATERIALS AND METHODS 



A small (9.3 mm carapace width) ovigerous 

 female M. sculptipes was collected 14 June 1978 by 

 the crew of the Harbor Branch Foundation RY Sea 

 Diver (cruise SD23, station #007), with a 20 ft (6.1 

 m) otter trawl. The trawl sample was taken off the 



Manuscript accepted January 1981. 

 FISHERY BULLETIN: VOL. 79, NO. 3, 1981. 



487 



