GOPALAKRISHNAN: BIOLOGY AND TAXONOMY OF NEMATOSCELIS 



arranged in three rows (Figure 6e,f ). Proximal process of petasma with serrations in two 



rows (Figure 7a,b) 2 



lb. Second pair of thoracic legs with long spines from terminal segment (dactylus) only. Third 

 to fourth thoracic legs with only two segments beyond knee, and fifth and sixth with only 

 one. Maxillule without a pseudexopod. Basis of maxilla with one lobe only. Ventrolateral 

 spine on coxa of antenna small or greatly reduced (Figure 4A,a-d). Cephalic ridge on 

 carapace absent or inconspicuous (Figure 5a-e). Eyes relatively small (Figure 4B,a-d). 

 Propodus of first leg with setae arranged in one or two rows (Figure 6a-d). Proximal 

 process of petasma without serrations, or when present in one row only (Figures 7c and 8) 3 



2a. Proximal process of petasma reaching almost middle of serrated margin of terminal 

 process (Figure 7a). Serrated part of terminal process slightly curved towards median 

 lobe. Propodus of first leg usually with six setae in outer (dorsal) row and five in middle 

 row A^. megalops 



2b. Proximal process reaching much beyond middle of distal part of terminal process (Figure 

 7b). Distal end of terminal process greatly curved towards median lobe, reaching slightly 

 over distal end of proximal process. Propodus of first leg usually with five setae in dorsal 

 row and four in middle row N. difficilus 



3a. Propodus of first thoracic leg with setae arranged in two separate rows (Figure 6c,d). Lateral 

 process of petasma much longer than both terminal and spine-shaped processes (Figures 

 7c and 8a). Distal end of lateral process serrated 4 



3b. Propodus of first thoracic leg dorsoventrally flattened and furnished with setae in one row 

 only (Figure 6a,b). Lateral process of petasma much smaller than both terminal and 

 spine-shaped processes (Figure 8b-d). No serrations on lateral process or any other 

 processes of petasma 5 



4a. Ventrolateral spine on coxa of antenna highly reduced to a hump (Figure 4A,d). Lower part 

 of eye much smaller than upper part (Figure 4B,d). A long seta projecting from dorsal 

 surface,of dactylus of first thoracic leg (Figure 6d). Distal end of lateral process always 

 reaching beyond distal end of proximal process (Figure 8a) A^. tenella 



4b. Ventrolateral spine on coxa of antenna not reduced to a hump (Figure 4A,a). Lower part of 

 eye larger than or nearly equal to upper part (Figure 4B,a). No seta on dorsal surface of 

 dactylus of first thoracic leg (Figure 6c). Distal end of lateral process not reaching beyond 

 distal end of proximal process (exception: "old forms" from the Pacific Ocean to be 

 discussed in a later section) (Figure 7c) N. gracilis 



5a. Upper part of eye slightly narrower than lower part (Figures 4B,b and 9c). Propodus of first 

 thoracic leg with less convex inner margin (Figure 6b and 9d). Keel on carapace less 

 prominent and without conspicuous hump. Abdominal segments without any elevated 

 dorsal keels. Shapes and relative lengths of processes of petasma as shown in Figure 8c,d. 

 Lengths of propodus and carpus of first leg nearly equal 6 



5b. Upper lobe of eye slightly wider than lower lobe; lateral evagination much deeper in upper 

 than in lower lobe (Figure 4B,c). Propodus of first thoracic leg with highly convex inner 

 margin (Figure 6a). Keel on carapace quite prominent and with conspicuous hump 

 (Figures 5c and lb). Fourth and fifth abdominal segment characterized by less elevated 

 dorsal keels. Carpus of first leg shorter than propodus. Shapes and relative lengths of 

 processes of petasma as shown in Figure 8b A^. microps 



6a. Proximal process thick; terminal process much shorter than both proximal and spine- 

 shaped processes. Lateral process small. Median lobe greatly flattened and broad; its 

 outer and inner margins broadly convex, inner margin forming an acute distal angle with 

 outer margin (Figure 8c). Adult female without lateral denticle on carapace N. lobata 



6b. Proximal process thin, a little shorter than terminal process; lateral process slightly curved 

 toward median lobe, its distal end reaching to or almost to distal end of proximal process 

 (Figure 8d). Adult female with lateral denticle on carapace A'^. atlantica 



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