ANDRYSZAK and GORE: COMPLETE LARVAL DEVELOPMENT OF MICROPANOPE SCULPTIPES 



The antennal exopodite of larval M. sculptipes is 

 one-sixth to one-fifth the length of the protopodite, 

 and therefore may be considered an intermediate 

 form in the antennal classification schemes of 

 Hyman (1925), Lebour (1928), and Aikawa (1929). 

 The antennal configuration of M. sculptipes has 

 been shown here to be distinctive from many other 

 xanthid larvae, and it may be a general charac- 

 teristic of the genus MjcropanojDe(sensulato). This 

 contention is supported by a nearly identical an- 

 tennal configuration for zoeae of M. barbadensis . 

 However, similar antennal morphological charac- 

 teristics are seen in the larvae oi Paramedaeus 

 noelensis and Heterozius rotundifrons . This simi- 

 larity in antennal morphology allows establish- 

 ment of a separate antennal classification typed 

 "Group E" for larvae of the Xanthidae (Gore et al. 

 1981). Larvae in this grouping might be consid- 

 ered more advanced than most xanthids, although 

 P. noelensis has four zoeal stages and is otherwise 

 similar in development to other members of the 

 family. Heterozius has two zoeal stages but, as 

 noted by Wear (1968), may not belong in the 

 Xanthidae. 



Status of Micropanope in Family Xanthidae 



Guinot (1967) discussed systematic relation- 

 ships among adults of the Xanthidae and consid- 

 ered the genus Micropanope to be a mixture of 

 several distinct generic groups which were inter- 

 mediate between the genera Panopeus and 

 Pilumnus. She concluded Micropanope to be more 

 closely related io Panopeus than io Pilumnus. 



A comparison of the overall larval morphology 

 of M. sculptipes with Panopeus herbstii and 

 Pilumnus dasypodus (Table 2) reveals a much 

 closer similarity between larvae of M. sculptipes 

 and Panopeus herbstii than between M. sculptipes 

 and Pilumnus dasypodus . Examination of the an- 

 tennal structure for these three species shows that 

 the length of the antennal exopodite relative to 

 that of the antennal protopodite for M. sculptipes 

 (exopodite one-sixth protopodite length) is inter- 

 mediate between the advanced state seen in 

 Panopeus herbstii (exopodite minute) and the 

 primitive state seen in Pilumnus dasypodus 

 (exopodite equals protopodite length), being more 

 similar to Panopeus herbstii. Assuming that the 

 antennal exopodite relative length is an indicator 

 of the degree of relative primitiveness among 

 xanthid species (Lebour 1928; Aikawa 1929), it can 

 be concluded on this larval character that Micro- 



panope is evolutionarily more closely related to 

 Panopeus than to Pilumnus. This finding supports 

 the contentions of Guinot (1967), and the apparent 

 alliance between both larvae and adults of 

 Micropanope and Panopeus emphasizes the im- 

 portance which larval taxonomy may have in de- 

 termining systematic and possible evolutionary 

 relationships within the complex family Xan- 

 thidae. 



ACKNOWLEDGMENTS 



We wish to thank the personnel of the Smith- 

 sonian Institution Fort Pierce Bureau for provid- 

 ing the materials and working space required for 

 this study. The senior author sincerely thanks 

 Robert H. Gore for making possible the predoc- 

 toral fellowship program, through which he was 

 funded, and for providing the benefit of his exper- 

 tise in larval development studies. Liberta E. 

 Scotto and Kim A. Wilson provided assistance in 

 laboratory work and a great deal of encourage- 

 ment. John Miller, Kim Wilson, Paula Mikkelsen, 

 Suzanne Bass, and the crew of the Sea Diver were 

 responsible for collecting the ovigerous specimen 

 used in this study. Nancy A. Kuhn translated arti- 

 cles written in French. 



LITERATURE CITED 



Aikawa, H. 



1929. On larval forms of some Brachynra. Rec. Oceanogr. 



Works Jpn. 2:17-55. 

 1937. Further notes on brachyuran larvae. Rec. 

 Oceanogr. Works Jpn. 9:87-162. 

 CHAMBERLAIN, N. A. 



1961. Studies on the larval development of Neopanope 

 texana sayi (Smith) and other crabs of the family Xan- 

 thidae (Brachyura). Johns Hopkins Univ., Chesapeake 

 Bay Inst., Tech. Rep. 22, 35 p. 



1962. Ecological studies of the larval development of 

 Rhithropanopeus harrisii (Xanthidae, Brachyura). 

 Johns Hopkins Univ., Chesapeake Bay Inst., Tech. 

 Rep. 28, 47 p. 



CosTLow, J. D., Jr., and C. G. BOOKHOUT. 



1961a. The larval stages of Panopeus herbstii Milne- 

 Edwards reared in the laboratory. J. Elisha Mitchell 

 Sci. Soc. 77:33-42. 



1961b. The larval development otEury panopeus depressus 

 (Smith) under laboratory conditions. Crustaceana 

 2:6-15. 



1966. Larval development of the crab, Hexapanopeus 

 angustifrons. Chesapeake Sci. 7:148-156. 



1967. The larval stages of the crab, Neopanope packardii 

 (Kingsley), in the laboratory. Bull. Mar. Sci. 17:52-63. 



1968. Larval development of the crab, Leptodius agassizii 

 A. Milne-Edwards in the laboratory (Brachyura, Xan- 

 thidae). Crustaceana Suppl. 2:203-213. 



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