FISHERY BULLETIN: VOL. 73, NO. 4 



GENUS NEMATOSCELIS GO SARS 



N. LOBATA HANSEN. 

 N GRACILIS HANSEN 

 N MICROPS CO SARS 

 N.ATLANTICA HANSEN 

 N TENELLA GO SARS 



NDIFFICILIS 

 N-MEGALOPS 



HANSEN 

 GOSARS 



NUMBER OF 



TELSON SPINES 



(TERMINAL) 



SEQUENTIAL DIFFERENTIATION OF PLEOPODS 



FURCILIA 



FURCILIA 2 



FURCILIA 3 



NUMBER OF 



TELSON SPINES 



(TERMINAL) 



Figure 2.-Developmental sequence of differentiation of pleopods and terminal spines of the telson in species of Nematoscelis 



(adapted from Gopalakrishnan 1973). 



Key for Identifying Furcilia Larvae of Nematoscelis 



la. Each terminal spine of telson with a pair of conspicuous lateral subspines (Figure 3A,a); 

 setules present only above these subspines. Fj stage with seven terminal spines and one 

 pair of non-setose pleopods; Fg with five terminal spines, one pair of setose pleopods and 

 three pairs of non-setose pleopods; F3 with three terminal spines, four pairs of setose 



pleopods and one pair of non-setose pleopods (Figure 2) 2 



lb. Each terminal spine of telson without subspines, but with lateral setules along three- 

 fourths of its length (Figure 3A,b). Fj stage with seven terminal spines and two pairs of 

 non-setose pleopods; Fg stage also with seven terminal spines but two pairs of setose 

 pleopods and three pairs of non-setose pleopods; F3 stage with five terminal spines and 



five pairs of setose pleopods (Figure 2) 5 



2a. Rostrum rectangular with truncated anterior end (Figure 3B,b,c) 3 



2b. Rostrum triangular with pointed anterior end (Figure 3B,a,d) 4 



3a. Carapace keel very large and hump shaped; rostrum usually curved downwards (Figure 

 3B,b); length of sixth abdominal segment relatively short and its ventral margin largely 



convex A. tenella 



3b. Carapace keel small, usually triangular shaped (Figure 3B,c), ventral margin ot sixth 



abdominal segment not convex A'', gracilis 



4a. Rostrum broad and stough, keel large and platelike; carapace compressed anteroposteriorly 



(Figure 3B,a) N. microps 



4b. Rostrum elongate and slender; keel less conspicuous (Figure 3B,d) N. atlanfica 



5a. Rostrum broad, thick and triangular (Figure 3B,e) N. megahps 



5b. Rostrum slender and narrow (Figure 3B,f ) N. difficilis 



Furcilia larvae of N. atlantica and N. lobata are complete the larval description of A^. lobata. This 

 difficult to separate. More samples are necessary to species is known to occur only in the semi-isolated 



800 



