FISHERY BULLETIN: VOL. 79. NO. 3 



Table 3. — Comparison of morphologically important megalopal characters for distinguishing Micropanope sculptipes from megalopae 

 of other western Atlantic species of Xanthidae based on descriptions and illustrations from different sources. 



Species 

 (description source) 



Frontal region 



Telson 



Micropanope sculptipes 



Neopanope sayi 

 (Chamberlain 1961) 



Neopanope texana 

 (McMahan 1967) 



Neopanope packardii 



(Costlow and Bookhout 1967) 



Panopeus herbstii 

 (Costlow and Bookhout 1961a) 



Eurypanopeus depressus 

 (Costlow and Bookhout 1961b) 



Hexapanopeus angustifrons 

 (Costlow and Bookhout 1966) 



Rhithropanopeus harnsii 

 (Chamberlain 1962) 



Pseudomedaeus agassizii 

 (Costlow and Bookhout 1968) 



Eurytium limosum 

 (Kurata') 



Pilumnus sayi 

 (Kurata') 



Pilumnus dasypodus 

 (Sandifer 1974) 



Menippe mercenaria 



(Kurata!) 

 Menippe nodifrons 



(Scotto 1979) 



Rostrum prominent, sharply rounded 

 Lateral horns prominent, 1/2 rostrum length, small lateral 

 spines bearing 2 apical setae 



4 long, plumose setae between rostrum and each lateral spine 

 Rostrum square, depressed into blunt bifid tooth 



Lateral spines blunt 



5 short setae between rostrum and each lateral spine 

 Rostrum blunt, depressed, notched 



Lateral spines small, pointed 



2 short setae between rostrum and each lateral spine 

 Rostrum long, pointed, depressed 

 Lateral spines short, pointed 

 No frontal setae figured 

 Rostrum stoutly pointed, depressed 

 Lateral spines stout, pointed slightly less than rostrum 

 length 



1 stout seta between rostrum and each lateral spine 

 Rostrum blunt, broadly triangular, depressed 



No lateral spines or frontal setae 



Rostrum broad, rounded, depressed 



Lateral horns prominent 



5 short setae between rostrum and each lateral horn 



Rostrum blunt, depressed bifid tooth 



No lateral spines 



2 short setae on each side of rostrum 

 Rostrum pointed, depressed 



Lateral spines stout, pointed, slightly shorter than rostrum 



2 small setae between rostrum and each lateral spine 

 Rostrum blunt, depressed bifid tooth 



Lateral horns prominent -rostrum length 



3-4 setae between rostrum and each lateral horn, 1 outer 



lateral horn seta 

 Rostrum short, blunt, depressed 

 No lateral spines 



3 short setae on each side of rostrum 

 Rostrum broad, rounded, depressed 

 No lateral spines or frontal setae 



Rostrum broad, depressed, shallow median groove 



No lateral spines or frontal setae figured 



Rostrum strongly deflexed, blunt, rounded, distinct median 



cleft 

 Interorbitai prominences lateral to rostrum angular, blunt 



Rectangular, 2 pairs dorsal setae, 

 3 serrated spines at each outer corner, 

 3 plumose setae along shallow median sinus 



Rounded posteriorly 



Rounded posteriorly, 3 pairs dorsal setae, 3 

 posterior setae 



Caudal margin with 8 stiff spines 



Rounded posteriorly, 3-6 stiff caudal spines 



Rectangular, posterior margin with 3 short 

 caudal setae, 2 longer setae on each side 



Rectangular, posterior margin with 2-4 short 

 setae 



Rectangular, few short setae on posterior 

 margin 



Rectangular, 4 short setae on posterior 

 margin 



Rounded posteriorly 



Rounded posteriorly 



Rounded. 2 dorsal, 2 ventral setae; posterior 

 border unarmed (rarely with 1, 2 small 

 medial spines) 



Rounded, somewhat truncated posterior margin 



Subquadrate, 5 setae on posterior margin, 

 other setation variable 



'Kurata. H. 1970. Studies on the life histories of decapod Crustacea of Georgia. Unpubl. rep., 274 p. Univ. Georgia IVIar. Inst., Sapelo Island. 



the importance of larval characters in determin- 

 ing phylogenetic relationships among brachyuran 

 taxa, with special reference to the genus Menippe, 

 and the families Xanthidae and Cancridae. Al- 

 though Lebour (1928) enumerated several distin- 

 guishing morphological characters of xanthid lar- 

 vae, including number of zoeal stages, carapacial 

 armature, antennal morphology, abdominal mor- 

 phology, and telson armature. Wear (1968, 1970) 

 has shown that few of these are now valid. Even so, 

 the larval characteristics of Micropanope 

 sculptipes generally agree with Lebour 's classical 

 categorization of morphological characteristics of 

 the Xanthidae. Moreover, the antennal structure 

 of M. sculptipes differs in important respects, dis- 

 tinctive for the genus. 



Hyman (1925) and Lebour (1928) divided the 

 antennal morphology of xanthid larvae into two or 



three distinctive groups: antennal exopodite 

 either minute, nearly equal to protopodite length, 

 or about three-fourths protopodite length. Shorter 

 antennal exopodites were considered indicative of 

 evolutionarily more advanced species. 



Aikawa (1929) recognized four types of anten- 

 nae (A, B, C, D), also based on the relative length of 

 the peduncle ( = protopodite) to that of the exopo- 

 dite. In Type A the protopodite and exopodite are 

 nearly equal in length, a condition considered 

 most primitive; in Type B the exopodite is one-half 

 to three-fourths of the protopodite length, a type 

 characteristic of most brachyuran zoeae; in Type C 

 the exopodite is minute, these are the most highly 

 developed. Type D antennae have a simple, incon- 

 spicuous spiny process which is shorter than 

 either the rostrum or the antennule, and is consid- 

 ered to be a deviation. 



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