Distribution 



Pacific Ocean 



Indo-Pacific: ?Vervoort (1946), 1,845-2,500 m. 

 Atlantic Ocean 



West: Wheeler (1970), 2,000-4,000 m. 



Genus M/M0CAL/iAr{7s Farran, 1908 



Type Species: Mimocalanus cultrifer Farran, 1908. 



Description 



Rostrum absent. Pi Rel without outer distal spine; 

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

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

 outer seta. Surface of swimming leg segments without 

 spines. Caudal rami symmetrical. Caudal setae usual- 

 ly incomplete on specimens examined: no trace of out- 

 er (sixth) seta; outer and inner terminal setae usually 

 completely detached; middle 2 terminal setae usually 

 broken at bases; inner seta directed ventrally, small or 

 reduced. 



Female. — Prosome in dorsal view slender to robust 

 ovoid. Most species with distinct indented sclerotiza- 

 tion about midlength on Ce; sclerotization direct ex- 

 tension of sclerotized supporting margin of labrum, 

 and perhaps serving as strengthened attachment for 

 mandibular muscles. (Sclerotization reduced in adult 

 males, where mandible also reduced.) Th5 lateral cor- 

 ners prolonged, at least to midgenital segment. Thl- 

 Th4 without lateral spinules. Prosome length nearly 4 

 to nearly 5 times urosome. Caudal rami length 1-1 V2 

 times width. 



Al segment 2 length about equaling segment 1 (M. 

 oualis segment 2 length about I'a times segment 1). 

 Segments 8 and 9 partly fused (completely fused on 

 M. ovalis). Al narrowing between segments 9-11. Al 

 exceeding caudal rami by 1-4 segments (only reaching 

 genital segment on M. oualis). Armature as in 

 Spinocalanus female (Table 4). Esthete bases smaller 

 than on Spinocalanus female. 



A2 (Fig. 194) Re length exceeding Ri by 20%. Rel 

 without setae. Re2 and ReS separate; Re2 without 

 setae. 



Mn B2 with 2 or 3 inner setae, surface nude. Ril 

 surface nude. 



Mxl gnathobase proximal surface without spinules; 

 distal anterior seta present. Inner lobe-1 with 4 setae; 

 inner lobes- 1-2 relatively large. Proximal part of Ri 

 with 3 or 7 proximal and 3 or 7 distal setae. Small 

 nude outer lobe-2 sometimes present. 



Mx2 (Fig. 197) length 2 times width; without prox- 

 imal outer hump. Lobe-5 with 3 strong and 1 reduced 

 setae; posterior surface of base without spines. Lobe-6 

 reduced, apparently with only 1 seta. Ri segments 

 reduced. Mx2 outer seta apparently absent. 



Mxp Bl-2 without transverse spine-comb. Bl with 



proximal group of 2 setae, midlength group of 3 setae, 

 and distal group of 3 or 4 setae. B2 with longitudinal 

 row of reduced spinules or denticles (M. ovalis with 

 stiff hairs); 3 setae about midlength and 2 distal setae 

 (M. ovalis with 2 setae midlength, 1 seta more distal, 

 and 2 distal setae). Ri4-5 outer setae usually 

 moderately long, with very long plumes each side; Ri5 

 inner edge without spinules. 



P2-P4 Re terminal seta with finely serrate outer 

 edge (48-90 teeth); outer flange wide. 



P4 Bl transverse row of thin setules on posterior 

 surface proximal to inner seta (M. crassus without 

 transverse row of setules and without inner seta). 



Male. — Prosome in dorsal view elongate to robust 

 ovoid; anterior varying with species. Reduced 

 sclerotization midlength on Ce in adult; male stage V 

 sclerotization as on adult female. Ce not expanded. 

 Ce and Thl separate. Prosome length 2 '4-3 '4 times 

 urosome. Anal segment not reduced, length V3-I times 

 caudal ramus. Caudal rami length 1-1 '2 times width. 



Al segment 2 length about equaling segment 1; seg- 

 ment 10 partly fused with segment 9; right segment 20 

 merging with segment 21, as on other left-handed 

 species; segment 25 not reduced. Al narrowing 

 between segments 8-10. Esthete bases very small. Ar- 

 mature given in Table 4. 



Swimming legs generally similar to those on cor- 

 responding female. P4 Bl without inner transverse 

 row of setules on posterior surface; some species with 

 inner seta. 



P5 uniramus, left-handed, variably asymmetrical; 

 Re essentially 3-segmented, Rel-2 may be partly 

 fused. 



Key to the Species of Mimocalanus 



1. P2Ri2 with 1 outer seta (4) 



P2 Ri2 with no outer seta (2) 



2. P2-P3 Bl without inner seta; P3-P4 Ri3 with no 



outer seta 8. M. crassus 



P2-P3 Bl with inner seta; P3-P4 Ri3 with 1 outer 

 seta (3) 



3. Female: Al not reaching beyond genital seg- 



ment; Al segment 2 length 1 ' 2 times segment 

 1. Pi Ri outer lobe reduced. (Male unknown.) 



6. M. ovalis 



Female: Al reaching beyond caudal rami; Al 

 segments 1 and 2 lengths about equal. PI Ri 

 outer lobe not reduced. (Male unknown.) . 



I. M. cultrifer 



4. Length greater than 4.0 mm. (Male unknown.) 



3. M. major 



Length less than 4.0 mm (5) 



5. P2-P4 Ri2 with broadly inflated inner edge. 



(Male unknown.) 4. M. inflatus 



P2-P4 Ri2 not inflated (6) 



6. Female: length less than 2.0 mm; Th4 and Th5 



partly fused; inner caudal seta small, not re- 



67 



