Spinocalanus spinosus, female 



Figure 84.— PI; sample 5 (Table 3); 

 scale D. 



3-4 rows of spines. B2 inner surface with cluster of thin 

 setules. 



P2 Re3 with 2 distal rows of short spines on 

 posterior surface. 



P3 Re2 with midlength oblique row of strong spines 

 and distal row of denticles. Re3 with 3 evenly spaced 

 rows of short spines. Ri3 with 2 rows of strong spines. 



P4 Re2 with midlength oblique row of strong spines 

 and distal row of smaller spines. Re3 with 3 evenly 

 spaced rows of spines, proximal spines longest, distal 

 spines shortest. 



Re terminal seta with following number of primary 

 teeth: P2 (30-36); P3 (28-33); P4 (29-32). 



Male.— Length 2.0-2.9 mm (Figs. 78, 79). Prosome 

 anterior irregular in dorsal view, posterior somewhat 

 rectangular; in lateral view with gentle forward slope. 

 Ce and Thl partly fused. Prosome length r'4 times 

 urosome. Caudal rami about as long as wide. 



Al reaching end of prosome; segment 1 with con- 

 spicuous cluster of setules on anterodorsal 

 surface. IV-2s, 2e; Vin-2s, 2e; XV-2s, le; XIX-ls, 

 le; right XX-0; left XX-le; remainder as Table 4. 



Mn B2 without distal setules; 2 short setae on inner 

 margin. Ril surface setules longer than on female. 

 Segmentation and setation of Re and Ri as on female. 

 Blade (Fig. 80) reduced; ventral tooth in some 

 specimens larger than figured. 



Mxl very fragile, gnathobase reduced to 1-2 small 

 spines on knob. 



Mx2 not robust; short, thin outer seta. Some inner 

 setae of reduced size, but probably number as on 

 female. 



Mxp (Fig. 81) with reduced size of setae; relatively 

 fragile. Ri4-5 outer setae short and flat; spinules on in- 

 ner edge of Ri5 as on female. 



PI Bl surface without setules, but hairs longer than 

 on female. B2 surface without setules, inner margin 

 hairs shorter than on female. Re3 posterior surface 

 spines relatively longer than on female. 



P2 Bl-2, Ri, and Re3 as on female. Re2 with circular 

 patch of spines on posterior surface. Terminal spine 

 with ca. 60 primary teeth. 



No specimens observed with P3 Re2-3; remaining 

 segments as on female. 



No specimens observed with P4 Re2-3. Bl without 

 setules on inner surface; inner seta reaching beyond 

 Ril; remaining segments a on female. 



P5 (Fig. 82) biramus, left-handed; reaching nearly 

 to end of urosome segment 2. Left Bl reaching one- 

 third to one-half length of right B2; left B2 reaching 

 middle of right Rel. Left and right legs about equal; 

 right Re, including moderately long, flat terminal 

 seta, longest; left and right Ri about equal. Order of 

 length, longest to shortest, of Re segments: left 1 = 2, 

 3; right 2, 1, 3. Each Rel with short, flat seta on distal 

 outer edge. Inner edge of left Re2-3 with hairs. Each 

 Re3 with 2 unequal, bladelike terminal setae. Ri im- 

 perfectly 2-segmented; left Ri reaching middle of left 

 Re3; right Ri reaching middle of right Re3. Each Ri 

 with long bladelike extension. 



Male stage V.— Length L95-1.97 mm. Left side of 

 Th2-Th3 with spinules (Arctic specimens). 



P5 (Fig. 83) biramus, symmetrical. Re imperfectly 

 2-segmented; small flat seta on distal edge of Rel; Re2 

 with 2 small flat terminal setae. Ri 1-segmented. 

 reaching nearly one-half length of Re, with small flat 

 terminal seta. 



Remarks 



Wolfenden's (1911) original description of S. 

 horridus included a figure of Mxp which clearly in- 

 dicates a transverse spine-comb on Bl. Park (1970) 

 likewise illustrated Mxp with spine-comb on Bl. 

 These are the only two investigators who have 

 described this species under this name. 



Tanaka (1937) described one female S. abyssalis, 

 which, except for lateral prosomal spinules, which 

 Tanaka did not mention, agrees with the description 

 of S. horridus given above. The prosomal spinules are 

 not particularly conspicuous unless viewed with 

 proper lighting; perhaps also, other populations, 

 besides the Arctic specimens of the present study, 

 have spinules only on one side, and this characteristic 

 might then not be noticed. The male described by 

 Tanaka is considered as ^\ brevicaudatus. Brodsky 

 (1950) recognized that Tanaka's specimens were not 

 S. abyssalis Giesbrecht. Minoda (1971) reported large 

 (1.95-2.2 mm) .S. abyssalis from the Bering Sea; his il- 

 lustration of Mxp indicates a transverse spine-comb 

 on Bl, and the scale to which it was drawn indicates 



40 



