SCOTTO I,AR\A1. I)p;VKL( )['MKNT < )K CUBAN STONE CRAB 



third group, also considered primitive, the anten- 

 nal exopodite is about three-fourths the length of 

 the protopodal process (this group was established 

 by Lebour to include Me nippe andEriphia ). There- 

 fore, regardless of classification scheme (Hyman's 

 or Lebour's), larvae of the genus Mtvn'ppe exhibit a 

 primitive antennal morphology. However, as will 

 he seen, the degree of primitiveness is relative. 



Aikawa ( 1929) classified four types of antennae 

 (A, B, C, and D) based on the ratio of length of 

 peduncle to that of exopodite. In the A type an- 

 tenna the exopodite and peduncle i = protopodal 

 proce.ss) are nearly equal in length. Aikawa also 

 considered this to be the most primitive condition 

 because other authors (e.g.. Caiman 1909) have 

 noted that the long exopodite is homologous with 

 the antennal scale of the Caridea. 



Xanthid larvae exhibiting A type antennae are 

 Pilumnus (considered by Hyman 1925 to be the 

 most primitive xanthid I, Hetcropan<ipe. and Av- 

 tiininus (Aikawa 1929, 1937; Lebour 1928). 



The typical B type antenna occurs most fre- 

 quently in brachyuran larvae. The exopodite is 

 about one-half to three-fourths the length of the 

 peduncle. Type B antennae are found in the larvae 

 of the xanthids Meuippc. Ehphia, Sphacrosius. 

 and Trapezia (Aikawa 19.37). This antennal mor- 

 phology, primitive by Hyman's standards, is con- 

 sidered by Aikawa (1929) to be intermediate in 

 development, but less advanced than the following 

 C type. 



The C type antenna consists of a long peduncle 

 and a very short spine ( = exopodite). This highly 

 advanced antenna is exhibited in the larvae of the 

 xanthids Pa /;opc;/,s (considered by Hyman 1925 to 

 be the most advanced xanthid), Eurypanopeus, 

 and Neapanope, among others (Aikawa 1929). 



Aikawa (1929) briefly described the D type an- 

 tenna (seen in the oxystome crab Philyra psiiitn 

 (Leucosiidae)) as a simple, inconspicu()us spiny 

 process shorter than either the rostrum or the 

 antennule, and considered it to be a deviation. 



The cancrids exhibit the intermediate B type 

 antenna seen in Menippe. Thus, in antennal fea- 

 tures, larvae of both Menippe and the Cancridae 

 would be more advanced than some of the xan- 

 thids, and equal to or less advanced than others. 



Abdominal Morphology 



A lateral knob occurs on the second abdominal 

 somite of most brachyuran larvae also on the 

 third somite of some xanthid larvae (Lebour 1928). 



Lebour did not attribute much significance to the 

 abdominal processes and was ambivalent in re- 

 garding these as either a primitive or advanced 

 feature. Later, Wear (1970). noted that "the pos- 

 terior pair of papillae Iknobsl may be absent" and 

 that "lateral spines on the third to fifth abdominal 

 segments is also a variable character, but these 

 occur in a great majority of xanthid larvae." Both 

 M . niidifrtitis and A'/, nieneniiria exhibit the lat- 

 eral papillae on the second and third abdominal 

 somites, as well as ventrolateral spines on the 

 third, fourth, and fifth somites, thereby agreeing 

 with the great majority of xanthid larvae. As 

 noted above, M . niereeuaria larvae may be distin- 

 guished from M . nodifrons larvae by possession of 

 a pair of dorsolateral spines on the fourth abdomi- 

 nal somite. In the more primitive Cancridae, lat- 

 eral knobs only occur on the second abdominal 

 somite, and lateral spines on the third to fifth 

 somites are much smaller than those of the 

 xanthid larvae (Aikawa 1937; Sastry 1977a, bi. 

 Thus Menippe larvae are more advanced than can- 

 crid larvae if additional spines indicate apomor- 

 phy- 



Telsonal Armature 



Menippe nmlifrons larvae have a typically 

 forked brachyuran telson with 6 setae anterior to 

 the furcae. However. 3 setae which become re- 

 duced in later stages, appear on the median por- 

 tion of the furcae, and one to three pair of extra, 

 shorter setae occur in posterior telsonal margin. 

 Lebour ( 1928) suggested that this type of telson is 

 "most near the embryonic form, and therefore 

 probably nearest the primitive form . . . ." The 

 extra internal setae along the posterior telsonal 

 margin first appear in the second zoeal stage of 

 both the xanthid M. nodifrona and the cancrid 

 Caneer horealis (Sastry 1977b). These internal 

 setae, if present in other xanthid larvae, do not 

 appear until the third zoeal stage, e.g., in 

 Paniipeus herhstii (Costlow and Bookhout 1961bl, 

 Eurypanopeus depre>:sn>i (Costlow and Bookhout 

 1961a), and Hexcipanopeus angiistifrons (Costlow 

 and Bookhout 1966), all more advanced forms 

 than Menippe. These data lend further support to 

 the primitive status of Menippe as compared with 

 other xanthid genera. 



In summary, using larval characters suggested 

 by Lebour (1928) to determine the primitive or 

 advanced status of decapod larvae, the genus 

 Menippe is phylogenetically more primitive than 



383 



