ANDRYSZAK and GORE: COMPLETE LARVAL DEVELOPMENT OF MICROPANOPE SCULPTIPES 



second and third somites. Menippe mercenaria and 

 M. nodifrons possess lateral hooks on the second 

 and third somites. Menippe mercenaria has a large 

 pair of dorsolateral spines on the fourth and fifth 

 somites, and develops posteroventral spines on the 

 third through fifth somites in its second and sub- 

 sequent zoeal stages. Menippe nodifrons has a 

 large pair of dorsolateral spines only on the fifth 

 somite, and develops posteroventral spines only on 

 the third and fourth somites in its second and 

 subsequent zoeal stages. 



Spination of the zoeal telson furca is varied 

 among xanthid species. Micropanope sculptipes 

 first zoeae have smooth telson furcae with 1 dorsal 

 and 1 lateral spine. Second and subsequent zoeal 

 stages have furcae with 1 dorsal spine, and 1 or 2 

 lateral spines. Neopanope sayi, N. texana, N. pac- 

 kardii, Eurypanopeus depressus, and Rhith- 

 ropanopeus harrisii have smooth telson furcae 

 with only 1 dorsal spine. Panopeus herbstii and 

 Pseudomedaeus agassizii have smooth telson fur- 

 cae with 1 dorsal spine and 2 lateral spines. 

 Hexapanopeus angustifrons has smooth telson fur- 

 cae without dorsal or lateral spines. Pt/amnus sayi 

 and P. dasypodus have spinous telson furcae with 

 1 dorsal spine and 2 lateral spines. The telson fur- 

 cae of Menippe are smooth and bear minute spines; 

 M. mercenaria has 1 dorsal and 1 lateral furcal 

 spines, andM. nodifrons has 1 dorsal and 2 lateral 

 furcal spines. 



Micropanope sculptipes megalopae may be 

 quickly distinguished from those of M. barbaden- 

 sis, because the latter is presently the only species 

 within the genus which bears spines on the coxa- 

 bases and ischia; in M. sculptipes only the bases 

 are so armed. 



Micropanope sculptipes may be separated from 

 other xanthid megalopae by examining the frontal 

 region ornamentation and telson structure (Table 

 3). The frontal region of M. sculptipes is or- 

 namented with a prominent rostrum and lateral 

 horns; each lateral horn has a small lateral 

 spine Jiear its base. Four long, plumose setae lay 

 between the rostrum and each lateral horn. 

 Panopeus herbstii, Neopanope packardii, and 

 Pseudomedaeus agassizii have pointed, depressed 

 rostrums. The lateral spines (horns) of A^. pac- 

 kardii are short, and the frontal region is devoid of 

 setae. Panopeus herbstii and Pseudomedaeus 

 agassizii have conspicuous lateral spines with 1 

 seta and 2 setae, respectively, between the rostrum 

 and each lateral spine. The remaining species dis- 

 cussed herein have rostrums which are reduced, 



broad, and generally rounded. The lateral spines 

 of Neopanope sayi and N. texana are short and 

 there are 5 setae and 2 setae, respectively, between 

 the rostrum and each lateral spine. Hexapanopeus 

 angustifrons and Eurytium limosum have promi- 

 nent lateral horns which equal or exceed the ros- 

 trum length. Five setae and two setae are present 

 between the rostrum and each lateral spine in H. 

 angustifrons andE. limosum, respectively. No lat- 

 eral horns are found in Rhithropanopeus harrisii 

 or Eurypanopeus depressus; 2 setae are found lat- 

 eral to the rostrum in the former species while no 

 setae are present in the latter species. No lateral 

 horns are found in Pilumnus sayi or P. dasypodus, 

 and 3 setae are present on either side of the ros- 

 trum in both species. The rostrums of Menippe 

 mercenaria and M. nodifrons are broad and have a 

 distinct median cleft. No lateral horns or setae are 

 present in M. mercenaria, but bluntly angular in- 

 terorbital protuberances and a few small, scat- 

 tered setae are found in the frontal region of M. 

 nodifrons . 



The telson of Micropanope sculptipes is rectan- 

 gular with 2 pairs of dorsal setae, 3 serrated spines 

 at each posterolateral angle, and 3 plumose setae 

 along the shallow median telson sinus. Rectangu- 

 lar telsons are found in E. depressus, H. angusti- 

 frons, Pseudomedaeus agassizii, and R. harrisii. 

 Eurypanopeus depressus has 3 short caudal setae 

 with 2 longer setae on either side. Hexapanopeus 

 angustifrons and P. agassizii have 2 to 4 short 

 setae and 4 short setae, respectively, along the 

 posterior telson margin. Rhithropanopeus harrisii 

 has a few short setae along its posterior telson 

 margin. Rounded (convex) posterior telson mar- 

 gins are found in N. sayi, M. texana, N. packardii, 

 Panopeus herbstii, and Eurytium limosum. 

 Neopanope texana has 3 pairs of dorsal telson setae 

 and 3 setae along the posterior telson margin, and 

 N. packardii has 8 stiff spines along its telson 

 caudal margin. Panopeus herbstii has 3 to 6 stiff 

 caudal telson spines. The telsons of Pilumnus sayi 

 and P. dasypodus are posteriorly rounded; P. 

 dasypodus has 2 dorsal and 2 ventral setae, and a 

 posterior border which is generally unarmed. 

 Menippe mercenaria has a rounded and somewhat 

 truncated posterior telson margin. The telson of 

 M. nodifrons is subquadrate with 5 setae along its 

 posterior margin; other telson setation is variable. 



Plesiomorphy and Larval Development 



Scotto (1979) provided a detailed discussion of 



503 



