KEY TO THE GENERA OF 

 SPINOCALANIDAE 



1. Pi Rel without outer distal spine; P2-P4 pos- 



terior surface of Ri2 without row of spines 



(3) 



Pi Rel with outer distal spine (reduced in male 

 Monacilla typica); P2-P4 posterior surface 

 of Ri2 with 2 rows of spines ( 1 row reduced to 

 small spinules on a few species) .... (2) 



2. Rostrum absent; male anal segment usually re- 



duced Spinocalanus 



Rostrum 2 strong points in female, reduced to 

 knob in male: male anal segment half length 

 of caudal ramus Monacilla 



3. Rostrum absent. Female prosome length at 



least 4 times urosome. Caudal ramus length 

 not more than 1 ' 2 times width. Male P5 

 uniramus. Re present on both legs .... 



Mimocalanus 



Rostrum 1 long cone. Female prosome length 

 about 3 times urosome. Caudal ramus length 

 about 2 times width. Male P5 uniramus, Re 

 present on left leg only . . Teneriforma naso 



Genus Spinocalanus Giesbrecht, 1888 



Type SpecieS: Spinocalanus abyssalis Giesbrecht, 

 1888. 



Description 



Rostrum absent. PI Rel with outer distal spine; 

 Rel-2 together longer than Re3; Ri with 1-3 inner 

 setae. P2 Ri2 with 0-1 outer seta. P3-P4 Ri3 with 2 

 outer setae (S. polaris with 1 outer seta). Posterior 

 surface of certain segments of swimming legs with 

 rows of spines (see below). Caudal rami and caudal 

 setae sometimes asymmetrical. 



Female. — Prosome in dorsal view slender to robust 

 ovoid. Th5 lateral corners sometimes prolonged; Thl- 

 Th4 sometimes with lateral spinules, sometimes vary- 

 ing in number left to right. Prosome length 2%-3y3 

 times urosome (5. angusticeps, S. antarcticus, and S. 

 validus about 4' 4). Caudal ramus length 1-2 times 

 width. 



Al segment 2 length about 1'2 times segment 1; 

 segments 8 and 9 fused. Al usually exceeding caudal 

 rami by 1-4 segments (see S. angusticeps, S. magnus, 

 and .S. validus). Armature given in Table 4. 



A2 Re length exceeds Ri by 20''c. Rel with 0-2 setae; 

 Re2 and Re3 fused; Re2 with 2 setae. 



Mn B2 with 4 inner setae, usually also with distal 

 row of long setules on anterior surface (and then also 

 with row of long setules on Ril surface). 



Mxl gnathobase posterior surface with proximal 

 clusters of spinules and denticles; proximal posterior 

 surface with 3 or 4 setae; distal anterior seta present or 



absent. Inner lobe-1 with 6 setae. Proximal part of Ri 

 with 4 proximal and 5 distal setae. Outer lobe-2 ab- 

 sent. 



Mx2 length I'a-Pi times width; small to strong 

 proximal outer hump, usually armed with hairs, 

 setules, and/or spinules. Lobe-5 with 4 strong setae; 

 posterior surface of base may have spines. Lobe-6 

 small, with 2 setae (1 seta small). Ri segments not 

 reduced. Mx2 outer seta present or, apparently, ab- 

 sent. 



Mxp Bl sometimes with transverse spine-comb 

 midlength on outer anterior and posterior edge. B2 

 sometimes also with transverse spine-comb about 

 one-third length on outer anterior and posterior edge. 

 Bl with 3 groups of 3 setae each. B2 with longitudinal 

 row of stiff hairs or stiff setules; 2 setae about 

 midlength, 1 seta more distal, and 2 distal setae. 

 Form of Ri4-5 outer setae varying with species. 



Pi Re3 sometimes with posterior surface spines. 



P2-P4 Re2 distal anterior surface with 1 row of 

 spinules. 



P2 Re2 posterior surface with 1 row of spines 

 (perhaps 2 rows in i>. hirtus; no spines in S. 

 angusticeps or S. validus). P3-P4 Re2 posterior sur- 

 face with 1-2 rows of spines. 



P2-P3 Re3 posterior surface with 1-3 rows of spines 

 (none on P2 posterior surface in S. angusticeps or ,S'. 

 validus). P4 ReS with or without posterior surface 

 spines or spinules. 



P2-P4 Re terminal seta with moderately coarse 

 .serrate outer edge (20-50 primary teeth); outer flange 

 narrow. 



P2-P4 Ri2 posterior surface with 2 rows of spines; 1 

 row sometimes reduced to small spinules on a few 

 species. 



P3 Ri3 posterior surface usually with 2 rows of 

 spines, but at least 1 row of spines or denticles. P4 Ri3 

 posterior surface with 2 rows of spines. 



P4 Bl with transverse row of setules (spinules on S. 

 polaris) on posterior surface near inner seta. 



Male. — Prosome in dorsal view usually not ovoid; 

 anterior irregular or rounded, with central knoblike 

 protrusion; posterior usually somewhat rectangular. 

 Ce expanded dorsolaterally, nearly covering Thl (only 

 slightly in S\ magnus and not at all in S. angusticeps 

 and S. antarcticus). Ce and Thl separate or partly 

 fused. Prosome length 1^3-2% times urosome. Anal 

 segment usually reduced (except one-half to two- 

 thirds length of caudal ramus in S. angusticeps, S. ant- 

 arcticus, S. magnus, and S. validus). Caudal ramus 

 length 1-1-4 times width. 



Al segment 2 somewhat longer than segment 1; seg- 

 ment 10 partly fused with segment 9; segment 25 

 reduced (except in S. angusticeps, S. antarcticus, S. 

 magnus. and perhaps S. validus). Armature given in 

 Table 4. 



Swimming legs generally similar to those in cor- 

 responding female, although surface armament 

 sometimes variable; rows of spines on posterior sur- 



15 



