58 U.S. NATIONAL MUSEUM BULLETIN 2 78 



Fallotritella biscaynensis, new species 



Figures 27, 28, 53 



Diagnosis. — Since this genus is monotypic, the characters of the 

 genus are diagnostic for the species. 



Description. — Male holotype: Body spinose. Cephalon with 

 single dorsal anteriorly directed spine. Pereonite 1 with single postero- 

 dorsal spine. Pereonites 2-4 with trace of dorsal spine at midlength 

 and with posterodorsal spine. Pereonites 5-7 without spines. Length 



4 mm. 



Antenna 1 approximately length of pereonites 2-4, flagellum of 11 

 articles. Antenna 2 approximately length of peduncle of antenna 1. 



Mandibidar palp 3-segmented, setal formula for terminal article 

 1-5-1. Mandibles with 5-toothed incisor, lacinia mobilis toothed, 2 

 accessory plates on right mandible and 3 on left, 2 setae present. 

 Palp of maxiUa 1 with 2 apical and 2 medial setae, outer lobe with 

 6 serrate spines. Outer lobe of maxilliped with 3 apical setae and 1 

 seta at midlength on medial margin, inner lobe rounded with 2 apical 

 setae; dactylus of palp slightly curved with grasping margin serrate. 



Propodus of gnathopod 1 triangular with 2 proximal grasping 

 spines; grasping margins of dactylus and propodus not serrate, dac- 

 tylus with single tooth and seta at tip. Propodus of gnathopod 2 with 

 proximal grasping spine and distal notch, basis approximately length 

 of pereonite 2. 



Gills elliptical and sometimes held with long axis parallel to body. 



Pereopods 3 and 4, 1-segmented with single seta at tip. Pereopod 



5 inserted posteriorly on pereonite 5, propodus without grasping 

 spines. Propodus of pereopods 6 and 7 with 2 proximal grasping 

 spines. 



Abdomen %vith pair of setose lobes, 2 setae on anterior end of 

 abdomen; penes large and medial. 



Female allotjrpe: Body spinose. Cephalon vnth single dorsal an- 

 teriorly directed spine. Pereonite 1 with single posterodorsal spine. 

 Pereonite 2 wath trace of pair of dorsal spines at midlength and ^nth 

 single posterodorsal spine. Pereonites 3 and 4 with pair of dorsal 

 spines at midlength and single posterodorsal spine. Pereonite 5 with 

 trace of dorsal spine at midlength. Pereonites 6-7 without spines. 

 Length 2.5 mm. 



Antenna 1 approximately length of pereonites 3-5, flagellum of 5 

 articles. Antenna 2 approximately length of peduncle of antenna 1. 



Mouthparts as in male except setal formula for terminal article of 

 mandibular palp 1-4-1. 



Gnathopod 1 as in male. Gnathopod 2 as in male except propodal 

 notch absent. 



Gills as in male. 



