ANDRYSZAK and GORE: COMPLETE LARVAL DEVELOPMENT OF MICROPANOPE SCULPTIPES 



coxa with small basal tubercle, ischium with large 

 hooked spine and small dorsal tubercle. Bases of 

 pereiopods 2-5 (Figure 6H, I) with small median 

 spine; dactyls of pereiopods 2-4 with a row of 3 

 subterminal serrated spines, 1 terminal spine; 

 dactylus of pereiopod 5 with 1 subterminal ser- 

 rated spine, 3 long subterminal setae, 1 terminal 

 spine. 



Abdomen (Figure 6A-C). With 6 somites and 

 telson. Lateral pleura of somites 2-5 slightly over- 

 lap following segment; lateral hooks of somites 2 

 and 3 absent. Numerous setae cover dorsal sur- 

 faces and posterodorsal margins of all somites. 

 Pleopods biramous (Figure 6J) on somites 2-5, 

 uniramous on somite 6 (Figure 6K); exopodites 

 with plumose setae arranged (anteriorly to pos- 

 teriorly) 15 or 16, 13 or 14, 13 or 14, 11, 7 or 8; 

 endopodites of pleopods 2-5 wdth appendix interna 

 consisting of 2 terminal curved hooks. 



Telson (Figure 6K). Roughly rectangular with 2 

 pairs of dorsal setae. Lateral margins produced 

 posteriorly, forming slightly extended lobes, each 

 lobe bearing 3 serrated spines of variable length; 

 posterior margin shallowly sinuous, with 3 

 plumose setae. 



Color. The one megalopa died before color notes 

 could be made. 



DISCUSSION 



Comparative Morphology of Micropanope 

 sculptipes With Other Xanthid Larvae 



The Xanthidae is a large and heterogeneous 

 family containing many genera and numerous 

 species. As a consequence, the larval stages of 

 many such species from the Atlantic and Pacific 

 Oceans have been studied over a long period (e.g., 

 Lebour 1928; Aikawa 1929, 1937; Wear 1968; Saba 

 et al. 1978). In the western Atlantic, larval devel- 

 opment is reliably known either completely or in 

 part for at least 10 genera and 15 species, in addi- 

 tion to several other genera and species which are 

 less certain because identifications were based on 

 planktonic material. As might be expected, there 

 exist numerous characters, both shared and un- 

 shared, in the larval stages, so that comparison 

 among the species and genera is often quite diffi- 

 cult. Readily observable morphological characters 

 useful in distinguishing zoeae and megalopae of 

 M. sculptipes from other western Atlantic xanthid 

 species which may cooccur in the plankton include 

 those of the rostral spine, antenna, anterodorsal 



carapace setae, abdominal spination, telsonal fur- 

 cae spination, and armature on basal segments of 

 the pereiopods. 



Within the genus Micropanope (sensu lato), M. 

 sculptipes exhibits extremely close morphological 

 similarity (but not developmental similarity) with 

 the larvae of M. barbadensis (Gore et al. 1981). 

 Both species exhibit a type of antenna different 

 from the four categories established by Aikawa 

 (1929) necessitating the creation of a fifth cate- 

 gory, Type E (Gore et al. 1981). This grouping 

 contains those larvae (presently only the two 

 species here considered) in which the antennal 

 exopodite is from one-fourth to one-seventh total 

 protopodite length. Other features allowing dis- 

 tinction between the two species include (in M. 

 sculptipes) the unadorned rostral carapace spine, 

 shorter lateral spines, unpaired lateral spines on 

 the telsonal furcae, a less lunate telson, more dis- 

 tinct spination on the antennal protopodite, a 

 single coxal seta on maxilliped 1, and the general 

 distribution of fine hairs on the anterodorsal area 

 of the carapace. The position and number of in- 

 tegumentary sensillae may prove to be of some 

 value, but this feature in the genus has only been 

 described for M. sculptipes. Gore et al. (1981) 

 worked with molted carapaces in describing M. 

 barbadensis and were unable to distinguish these 

 sensory pits clearly. 



A comparison of the larvae of M. sculptipes with 

 those in other western Atlantic xanthid species is 

 summarized in Table 2. The following differences 

 appear salient. The preorbital rostral hooks of M. 

 sculptipes, which are fully formed in the fourth 

 zoeal stage, are similar to, yet larger than, those 

 described for Panopeus herbstii. Pseudomedaeus 

 [ex Leptodius] agassizii also possesses similar 

 "secondary rostral spines," but these are much 

 more prominent from its second through fourth 

 zoeal stages. The rostrum of the other species 

 noted (see Table 2) remains generally straight and 

 unarmed throughout development. 



The antenna of M. sculptipes consists of a spi- 

 nous protopodite and has an exopodite which is 

 one-sixth the protopodite length. The species in 

 other genera possess an antennal protopodite 

 which is either nonspinous or noticeably less spi- 

 nous than that of Micropanope. The antennal 

 exopodite of these xanthid zoeae fall into three 

 general categories as described by Lebour (1928): 

 equal to protopodite length or Type A {Pilumnus 

 sayi, P. dasypodus); one-half to three-fourths pro- 

 topodite length or Type B {Menippe mercenaria, M. 



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