238 

 198 Infraorder PHYSOCEPHALATA Bowman and Gruner, 1973 



The pereon is usually not inflated spherically (except in the family Cysti- 

 somatidae) and, when viewed from above, does not differ from the pleon 

 in width. 



The head is well differentiated, large and longer than somite I of the 

 pereon. The eyes are usually large, well developed, and occupy a large 

 part of the surface of the head, but sometimes are reduced or completely 

 absent. Sexual dimorphism is generally distinct in the structure of anten- 

 nae II and sometimes of antennae I. The mandibles may be armed with a 

 strong cylindrical dentate process. Maxillae I usually lack an inner lobe. 

 In the maxillipeds the inner lobes are completely fused and the outer 

 lobes without a palp. Pereopods I and II often have a chela or subchela. 

 Pereopods V-VII never have retractile claws; their 2nd segment is highly 

 broadened, with a lobelike process. Pereopods VII may be reduced and 

 the number of segments reduced to two. 



The infraorder Physocephalata is divided into four superfamilies: 

 Vibilioidea, Phronimoidea, Lycaeopsoidea and Platysceloidea. The entire 

 group is quite heterogeneous and it is not always possible to establish 

 phylogenetic links between these superfamilies or even between the fam- 

 ilies within them. 



SUPERFAMILY VIBILIOIDEA DANA, 1852 



The antennae are straight and short. Antennae I originate from the frontal 

 part of the head; their flagellum consists of one large and sometimes 

 several rudimentary segments attached terminally to the 1st segment. 

 Antennae II originate from the frontal or ventral part of the head; they 

 are straight, few-segmented or rudimentary. Only pereopods I and II may 

 be armed with a chela or subchela. Pereopods III-VI are always simple. 

 Pereopods VII are simple or shortened, with modified distal segments. 

 The telson is free. 



The morphological differences among the representatives of the three 

 families constituting the superfamily Vibilioidea are so wide that their 

 inclusion in one superfamily seems artificial to some extent. 



VIII. Family VIBILIIDAE Dana, 1852 



These crustaceans are medium in size (0.5-20 mm). The body has a more 

 or less thick integument, slightly flattened laterally. The head is small, 

 with a weakly developed rostrum, more often without rostrum. The eyes, 

 if present, comprise dark pigmented ocelli and usually occupy only a part 

 of the lateral surface of the head; sometimes (genus Cyllopus) they are 

 highly developed, adjoining dorsally and occupying the entire surface 



