37. Spinocalanus usitatus Park, 1970 



(Figures 137-140) 



Spinocalanus pteronus Park, 1970, p. 487, fig. 43-50. 

 Spinocalanus usitatus Park, 1970, p. 487-489, fig. 

 51-54. 



Type Specimen: Holotype, female (1.62 mm), USNM 

 123785. 



Type Locality: Caribbean Sea, 487-950 m. 

 Material Studied: i female (1.88 mm), sample 31 

 (Table 3); 1 female (1.65 mm), sample 32; 1 female 

 (1.68 mm), sample 34; holotype, female (1.62 mm), 

 sample 55; 2 paratypes, females (1.38, 1.52 mm), sam- 

 ple 56. Also the following type specimens of 

 Spinocalanus pteronus: holotype, female (1.93 mm) 

 and 1 paratype, female (1.80 mm), sample 54; 5 

 paratypes, females (1.70-1.82 mm, mean = 1.76 mm), 

 sample 59. 



Description 



PI Ri with 2 inner setae; P2 Ri2 with 1 outer seta. 



Female.— Length 1.38-1.93 mm (Figs. 137, 138). 

 Body similar to S. spinosus; prosome in dorsal view 

 somewhat robust ovoid, head slightly truncate; in 

 lateral view with abrupt forward slope. Th4 and Th5 

 separate; Th5 lateral comers rounded, not prolonged. 

 Thl-Th4 with lateral spinules, number decreasing 



posteriorly, approximately even right and left. 

 Prosome length 2' 2-3 times urosome. 



Al incomplete on specimens examined. 



A2 Rel with 2 setae. 



Mx2 (Fig. 139) as on S. spinosus except posterior 

 surface of lobe-5 base with spines. 



Mxp (Fig. 140) as on S. spinosus except Bl with 

 transverse spine-comb on outer edge; oblique row of 

 setules on midanterior surface; distal hump with 

 oblique row of spinules on anterior surface; posterior 

 surface near distal outer edge with transverse row of 

 setules. B2 with strong transverse spine-comb; 

 longitudinal row of spinules. Remaining segments as 

 on S. spinosus. 



PI as on S. spinosus. 



Male. — Unknown. 



Remarks 



Park (1970) described a new species, S. pteronus, 

 apparently differing from S, usitatus only by the 

 presence, in S. pteronus, of laterally extended edges of 

 Ce. Ce of many Spinocalanus species has a tendency 

 to bend up along the lateral edge; sometimes only one 

 side is affected. This may be a reaction to the fixative, 

 or it may be a function of age of the specimen. Ce of 

 the holotype S. usitatus is turned out in this way on 

 the left side. Therefore, since the present study con- 

 siders that S. pteronus is essentially defined by a 

 possible artifact, the name S. usitatus ("usitatus" = 

 ordinary, usual) is retained for the species. 



Spinocalanus usitatus, female 



Figure 137.— Habitus, dorsal view; sample 31; scale A. 

 Figure 138.— Habitus, lateral view; sample 31; scale A. 

 Figure 139.— Mx2, inner and terminal setae omitted; sample 31; 



scale U. 

 Figure 140.— Mxp Bl-2; sample 31; scale D. 



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