2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 123 



Genus Procambarus Ortmann 



Procambarus Ortmann, 1905b, p. 437. 



Diagnosis. — First pleopod of first form male symmetrical or 

 asymmetrical and terminating in from two to five distinct parts, 

 which may be truncate, platelike, or spiniform; shoulder present or 

 absent on cephalic surface; if pleopods terminate in two parts, shoulder 

 always present some distance proximal to base of central projection. 

 Hooks present on ischia of third or fourth pereiopods, or both. Third 

 maxillipeds not conspicuously elongate and with row of teeth on 

 mesial margin of ischium. (Slightly modified from Hobbs, 1942, 

 p. 342). 



Procambarus pecki, new species 



Diagnosis. — Albinistic, eyes reduced and without pigment; 

 rostrum with subparallel or slightly convergent margins and with 

 marginal spines at base of acumen; postorbital ridges terminating ce- 

 phalically in spines; areola 5.2 to 6.4 times longer than broad with three 

 or four punctations across narrowest part and constituting 38.3 to 

 43.2 percent of total length of carapace; one to three cervical spines 

 present on each side of carapace. Simple hooks present on ischia of 

 third pereiopods of male. First pleopods of first form male symmet- 

 rical, reaching coxae of third pereiopods, with distinct shoulder on 

 cephalic surface proximal to base of central projection; mesial process 

 heavy, noncorneous, extending anterodistally considerably beyond 

 apex of central projection and somewhat enveloping base of latter, 

 distal end rounded; central projection slender, corneous, acute, and 

 directed cephalodistally at angle of approximately 55 degrees to 

 main shaft of appendage. Annulus ventralis somewhat globose but 

 with shallow longitudinal median trough and very short, caudally 

 situated, arclike sinus; proannular plate absent. 



Holotypic male, form i. — Albinistic, eyes reduced. Body sub- 

 cylindrical, only slightly depressed. Abdomen narrower than 

 thorax (7.8 and 8.8 mm in widest parts, respectively). Carapace 

 wider than high in region of caudodorsal margin of cervical groove 

 (8.8 and 7.3 mm) ; carapace widest slightly cephalic to midlength of 

 areola, 



Areola (fig. 3) moderately broad, 6.4 times longer than wide, with 

 three or four punctations across narrowest part. Cephalic section of 

 carapace 1.4 times longer than areola; length of areola 41.7 percent 

 of entire length of carapace. Rostrum with nonthickened elevated 

 convergent margins interrupted at base of acumen by long marginal 

 spines reaching midlength of penultimate podomere of peduncle of 

 antennule; acumen long and terminating apically in acute corneous 

 spine reaching base of flagellum of antenna and beyond distal podo- 



