REVISION OF DANIELSSENIA AND PSAMMIS 



79 



Archisenia 



Psammis 



Bathypsammis 



Fig. 23 Comparison of armature on distal endopod segment of P3 in Archisenia, Psammis and Bathypsammis. 



plumose seta and 2 inner, minute spiniform elements (com- 

 pared to 2 setae and 1 setule in between in Bathypsammis), 

 and by a detailed comparison of the distal transformations in 

 the male P2 endopod. Potential synapomorphies grouping 

 Psammis and Bathypsammis are: (i) rostrum with enlarged 

 anterior sensillae; (ii) the mandibular exopod with only 1 

 lateral and 2 apical setae; (iii) the fusion of the exopod and 

 baseoendopod in the female P5. Some species of Danielsse- 

 nia, however, also show a reduction in the setation of the 

 mandibular exopod (e.g. D. typica), and the fused P5 in 

 Bathypsammis might have been evolved convergently, since, 

 in other respects, it is very different from the condition in 

 Psammis. The rostral character might also be a product of 

 convergence since the enlargement of the anterior pair of 

 sensillae has evolved independently in a number of other 

 deepwater genera such as Paranannopus and Cylindronanno- 

 pus. 



Unique apomorphies for Psammis are: (i) reduction of the 

 mandibular endopod (1 lateral, 3 apical setae); (ii) the 

 specialized comb-like spines on the maxillulary coxal endite; 

 (iii) praecoxal endite of maxilla with only 2 spines; (iv) 

 extreme development of the posterior seta on the maxillipe- 

 dal basis; (v) elongation of P2 endopod, being longer than the 

 exopod; (vi) the apophysis on P2 enp-1 in both sexes; (vii) 

 reduction of the inner terminal seta on P3-P4 enp-3. In 

 Bathypsammis the unique apomorphies are confined to the 

 female as the male is unknown: (i) a very long outer basal 

 seta on the basis of PI; (ii) a very long caudal ramus with a 

 plume of setules on the inner distal corner; (iii) the form of 

 the setae on the endopodal lobe of the female P5. 



KEY TO GENERA OF PARANANNOPIDAE 



Remark. This key also includes Psammis kliei Smirnov, 

 1946, which will be placed in a genus by itself in a forthcom- 

 ing paper (Gee & Huys, in prep.), and the genus Carolinicola 

 Huys & Thistle, provisionally assigned to the Paranannop- 

 idae by Huys & Thistle (1989). 



1. P4 endopod 3-segmented 4. 



P4 endopod 2-segmented, 1-segmented or absent 2. 



2. Antennary exopod 1-segmented 



Carolinicola Huys & Thistle, 1989. 



Antennary exopod 3-segmented 3. 



3. Body short, robust; caudal rami setae IV and V long and 

 spinulose; P5 well developed, covering entire width of thoracic 



somite Paranannopus Lang, 1936. 



Body slender, cylindrical to vermiform; caudal rami setae IV 

 and V short and plumose; P5 a minute plate, located midven- 

 trally Cylindronannopus Coull, 1973. 



4. P2-P4 exp-1 without inner seta 5. 



P2-P4 exp-1 with inner seta 7. 



5. Antennules without plumose or pinnate spines/ 



setae Sentiropsis Huys & Gee, 1993. 



Antennules with plumose and/or pinnate spines/setae 6. 



6. Caudal ramus with distinct cluster of long setules at the inner 

 distal corner; P2 enp-2 with large apophysis in $ (and presum- 

 ably in d" also) Psammis kliei Smirnov, 1946. 



Caudal ramus without such cluster; P2 enp-2 with large apophy- 

 sis in d" only Danielssenia Boeck, 1872. 



7. P4 exp-3 with 8 setae/spines 8. 



P4 exp-3 with at most 7 setae/spines 13. 



8. P2 enp-2 with 2 inner setae 9. 



