. Bulletin of the Natural History Museum Zoology. 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 set
. Bulletin of the Natural History Museum Zoology. 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 ( 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 Psammi
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