Female.— Length 2.12-3.58 mm. Prosome in dorsal 

 view long ovoid, head rounded; in lateral view with 

 gentle, then abrupt, forward slope. Th4 and Th5 

 separated by fine suture; Th5 lateral corners slightly 

 prolonged, margins with stiff hairs. Prosome length 

 3'/3 times urosome. 



Mxp details unknown. 



P1-P4 Bl densely covered with short hairs. P2 Re2 

 posterior surface possibly with two rows of spines. P2- 

 P3 Re3 posterior surface with several small spines 

 along length. 



Male. — Unknown. 



Remarks 



Sars (1907) briefly described this species from a 

 single female; more information on the same 

 specimen, with illustrations, was added later (1924, 

 1925). Sars' figure of PI is lacking an inner seta on 

 Re3. 



Only three other specimens have been reported: 

 Vervoort (1946), one female from the Indo-Pacific, 

 653-1,000 m; Grice and Hulsemann (1965), two 

 females from the eastern North Atlantic, near the 

 type locality, 3,000-4,750 m. 



9. Spinocalanus spinosus Farran, 1908 



(Figure 84) 



Spinocalanus spinosus Farran, 1908, p. 27, pi. 1, fig. 



10. —Rose, 1933, p. 86, fig. 46. —Farran and Ver- 

 voort, 1951a, p. 2-3, fig. 4b, d-e. —Park, 1970, p. 

 485-487, fig. 37-42. 



Type Specimens: Syntypes, females, BM 1908.7.6.7- 



10. 



Type LOCALITY: Northeast Atlantic, 600-1,800 m. 



Material Studied: 3 females (1.67, 1.85, 1.87 mm), 



sample 5 (Table 3); 2 females (1.90, 1.90 mm), sample 



31. 



Description 



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



Female.— Length 1.67-2.0 mm. Prosome in dorsal 

 view somewhat robust ovoid, head slightly truncate; 

 in lateral view with abrupt forward slope. Th4 and 

 Th5 separate; Th5 lateral corners rounded, not 

 prolonged. Thl-Th4 with lateral spinules, number 

 decreasing posteriorly, approximately even right and 

 left. Prosome length 2^3-3 times urosome. Genital 

 segment about as long as wide, protruding ventrally 

 about one-third depth of rest of urosome; long hairs on 

 ventral surface of urosome segments 1-3. Caudal rami 

 length I'j times width, symmetrical. 



Al broken in specimens examined. 



A2 Rel with 2 setae; smaller seta easily detached. 



Mx2 with moderate, setule-covered hump on prox- 

 imal outer edge; outer seta present; posterior surface 

 of lobe-5 base without spines. 



Mxp Bl without spine-comb; strong transverse 

 spine-comb on B2. Ri4-5 outer setae nude, bladelike, 

 tapering toward each end; spinules on inner edge of 

 Ri5. 



PI (Fig. 84) Bl outer surface with few thin spinules; 

 inner margin with hairs. B2 anterior surface with few 

 thin spinules and setules. Outer distal anterior sur- 

 face of Rel-2 with row of spinules. Posterior surface of 

 Re3 with ca. 4 spines. Ri inner anterior surface with 

 row of thin spinules about midlength. 



Male. — Unknown. 



Remarks 



Farran (1908) briefly characterized Spinocalanus 

 spinosus by describing the lateral spinules on Thl- 

 Th4. This differentiated S. spinosus from the species 

 known up to that time. Since then, several closely 

 related species have been described (S. horridus, S. 

 usitatus, S. hoplites, and S. oligospinosus) which 

 seem to be distinguishable essentially by the presence 

 or absence of spines on the base of Mx2 lobe-5; the 

 presence and size, or absence of a transverse spine- 

 comb on Mxp Bl; the distribution of lateral spinules; 

 body size, and to some extent body shape. Specimens 

 of all of these "species" have been examined in the 

 present study and these characteristics are described 

 for each. They appear to be consistent and no transi- 

 tion forms have been observed. The only described 

 male is assigned to S. horridus; if these named-species 

 with spinulose prosomes are valid, there must be four 

 undescribed males. The co-occurrence of these spe- 

 cies hampers the interpretation of records of S. spino- 

 sus. 



Rose's (1933) description is from Farran (1908). 

 Farran and Vervoort (1951a) illustrated Mx2 without 

 spines on the base of lobe-5, consistent with Farran's 

 specimens from sample 5 (Table 3). Farran and Ver- 

 voort assigned some records of S. horridus to S. 

 spinosus, but the two species are considered distinct 

 in the present study (see S. horridus). 



Some records of very large "S. spinosus" (e.g., 

 Farran, 1929; Tanaka, 1956; Grice and Hulsemann, 

 1965, part) are interpreted as records of S. horridus. 

 Vervoort (1946) reported two female S. spinosus; he 

 stated that the Mxp of both was as described by 

 Wolfenden (1911) for S. horridus, i.e., with Bl 

 transverse spine-comb. Therefore, the larger (2.40 

 mm) specimen is considered in the present study to be 

 .S. horridus, while the smaller (1.80 mm) is considered 

 S. usitatus. 



Park (1970) did not describe -S. spinosus Mx2, but 

 the Mxp of his specimens was described as without Bl 

 spine-comb, consistent with the above description. 

 Park illustrated P2-P4; PI is illustrated in the present 

 study (Fig. 84). 



36 



