MORGAN and PROVENZANO: DEVELOPMENT OF SQL' ILL A KMPl'SA LARVAE AND POSTLARVA 



The second maxilliped of the remaining de- 

 scribed larvae is unarmed throughout the larval 

 development. To distinguish these genera, other 

 characters, such as the presence or absence of a 

 spine on the basis of the second maxilliped, must 

 be relied on. The spine is definitely born by seven 

 of the eight species oi OratosquiUa, but was not 

 mentioned for O. massavensis. Other species, 

 Squilla enipusa. P. armata schizodontia , Aliina 

 hyalina, and Meiosquilla lebouri have the spine, 

 while Harpiosqiiilla harpax and A. fasclata 

 definitely do not. 



The development of epipods on five pairs of 

 maxillipeds in older larvae appears to be a generic 

 character of Squilla as most other genera bear four 

 pairs of epipods. 



Characters such as rostral length and spinula- 

 tion. carapace and telson shape, size, and spinula- 

 tion, and overall body size and appearance have 

 been too variable within the limited number of 

 species presently described to use them in defining 

 generic associations of the larvae. Deriving 

 characters which apply to the youngest larvae as 

 well as the old will be difficult since far fewer 

 characters are present in the early stage larvae, 

 and the gross appearance of the young larvae is 

 very similar due to the small degree of differentia- 

 tion. Other characters such as antennular seg- 

 mentation, mouthpart morphology, setation, spi- 

 nation of the maxillipeds, or the presence of 

 ocular, antennular, epistomal, or basal uropodal 

 spines may also need to be examined. The setation 

 and spination of the first maxilliped may be of 

 great value in defining alliances of the species as 

 well as in making specific determinations. How- 

 ever, many more complete descriptions of the lar- 

 val developments undergone by the various 

 species must be accomplished before larval 

 characters can be used in establishing generic re- 

 lationships. 



The postlarva of Squilla empusa exh-ibited the 

 basic features of first stage postlarva as deter- 

 mined for other species by Alikunhi (1967). These 

 include the absence of anterolateral spines on the 

 carapace, the extremely poorly developed carina- 

 tion of the carapace, acutely pointed marginal 

 denticles of the telson, and moveable apices of the 

 submedian spines of the telson. As with the adult, 

 the postlarva possesses the full complement of 

 teeth on the raptorial dactylus, just as Alikunhi 

 11967) found. Furthermore, the five pairs of 

 epipods found in the adult are also possessed by 

 the postlarva. Other adult characters were de- 



veloped upon the next molt. The dorsal carinations 

 of the carapace were developed, the lateral proces- 

 ses of the exposed thoracic somites five through 

 eight resembled those of the adult, the marginal 

 denticles of the telson were not as acute, and the 

 submedian spines were fixed. The abdominal spi- 

 nal formula was still not equal to that of the adult. 

 Nevertheless, after the postlarva had undergone 

 its first molt more than enough characters were 

 shared with the adult to make a definite determi- 

 nation of the species. 



CONCLUSIONS 



1. Squilla einpusa undergoes nine pelagic 

 stages before attaining the postlarval stage. 



2. The last stage stomatopod larva and post- 

 larva described by Faxon (1882) are not S. 

 t'inpusd. 



3. Larvae of .S. cmputia may be identified by the 

 spinules of the carapace and the inter- 

 mediate denticles of the telson. Stages I and 

 II possess four spinules on the lateral margin 

 of the carapace and four intermediate denti- 

 cles. The third to ninth stages are armed with 

 six spinules on the lateral margin of the 

 carapace. There are two anterior and three 

 posterior spinules all ventralh' directed, and 

 one median spinule laterally directed. The 

 telsons of stages III to I.X have 8 to 10 inter- 

 mediate denticles. 



4. Rostral length and spinulation. carapace and 

 telson size and spinulation, and overall body 

 size and appearance probably are specific 

 rather than generic characters. 



5. The presence or absence of teeth on the dac- 

 tylus of the second maxilliped. the presence 

 or absence of a spine on the basis of the sec- 

 ond maxilliped. and the number of epipods 

 may all be useful characters in determining 

 generic status of larvae belonging to the 

 Squillidae. However, many more complete 

 descriptions of the larval developments un- 

 dergone by the various species are needed 

 before larval characters can be used in estab- 

 lishing generic relationships. 



ACKNOWLEDGMENTS 



We are indebted to the National Science Found- 

 ation for its support of this work under grant 

 DEB76-11716 to the Old Dommion University Re- 

 search Foundation. 



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