HAYNES; EARLY ZOEAL STAGES OF HIPPOLYTinAE 



(1936) illustrated a whole zoea she believed was a 

 zoeal stage of E. fabricii later than Stephensen's 

 "last" stage. Pike and Williamson (1961), from 

 development of zoeae of the genus Eualus, showed 

 that Stephensen's "youngest" stage is Stage III; 

 the "intermediate" stage is Stage IV; and the 

 "oldest" stage is Stage V or VI. They believed that 

 the zoea illustrated by Frost (1936) is probably 

 Stage VI or VII. 



Although Stephensen's and Frost's E. fabricii 

 zoeae are later stages than my zoeae, they can be 

 compared with my zoeae by the presence of pos- 

 terolateral spines on abdominal somites, length 

 of the antennal flagellum, and number of setae 

 fringing the antennal scale. My E. fabricii zoeae 

 have posterolateral spines on abdominal somites 4 

 and 5; Stephensen's and Frost's zoeae do not. The 

 antennal flagellum in Stages I and II of my E. 

 fabricii zoeae is about 1.5 times the length of the 

 antennal scale, and the antennal scale has 13 

 setae in Stage I and 16 or 17 setae in Stage II. In the 

 "youngest" stage (Stage III zoeae) described by 

 Stephensen, the length of the antennal flagellum 

 is still only about one-half the length of the 

 antennal scale, and the number of setae on the 

 antennal scale does not exceed 11. Stephensen's 

 and Frost's zoeae apparently belong to a species 

 other than E. fabricii. 



Pike and Williamson ( 1961) noted that the zoeae 

 described by Stephensen (1916, 1935) and Frost 

 (1936) as S. fabricii ( = E. fabricii) are similar to 

 zoeae ofE. pusiolus. The zoeae of both species lack 

 abdominal spines and have exopodites on pere- 

 opods 1-4. However, E. fabricii zoeae are larger, 

 have a longer rostrum, and have a well-developed 

 antennal spine on the anterior margin of the 

 carapace in late zoeal stages (compared with E. 

 pusiolus zoeae). On the basis of Pike and William- 

 son's comparison of zoeae of E. fabricii and 

 E. pusiolus, Makarov (1967) suggested that his 

 "Eualus sp. A" series of zoeae from the west 

 Kamchatka shelf is either E. pusiolus or E. 

 fabricii. According to Makarov, "Eualus sp. A" 

 zoeae are nearly identical to zoeae of E. pusiolus 

 described by Pike and Williamson (1961), but 

 because Makarov's zoeae are larger, especially in 

 the later stages, he speculated that "Eualus sp. A" 

 zoeae might be E. fabricii zoeae. 



Stage I and II zoeae of Makarov's "Eualus sp. A" 

 differ considerably from my Stage I and II zoeae of 

 E. fabricii. The zoeae of "Eualus sp. A" are 

 markedly smaller (Stages I and II of "Eualus sp. 



A" are 2.8 mm and 3.2 mm long, respectively; 

 Stage I and II E. fabricii are 3.7 mm and 4.1 mm 

 long, respectively). The rostrum of Makarov's 

 zoeae is minute; the abdomen lacks spines; and the 

 antennal flagellum is noticeably shorter than the 

 antennal flagellum of my Stage I and II E. fabricii. 



Spirontocaris arcuata 



Pike and Williamson (1961) described a Stage I 

 zoeae of S. spinus and S. lilljeborgii hatched from 

 known parentage and a Stage II zoeaofS.phippsii 

 collected from plankton. My Stage I zoeae of S. 

 arcuata are clearly different from these zoeae. 

 Stage I zoeae of S. arcuata differ from those of S. 

 spinus and S. lilljeborgii in shape of rostrum, 

 armature of carapace and abdomen, and setation 

 of antennule and antennae. Stage I S. arcuata 

 zoeae have a short rostrum that does not project 

 beyond the anterior margin of the eyes. In Stage I 

 zoeae of S. spinus and S. lilljeborgii and Stage II 

 zoeae of S. phippsii, a prominent rostrum projects 

 anteriorly beyond the eyes to about three-fourths 

 the length of the antennular peduncle. The cara- 

 pace of my specimens of S. arcuata does not have 

 supraorbital spines but has spines along the 

 anteroventral margin. However, in Stage I S. 

 spinus and S. lilljeborgii and Stage II .S. phippsii, 

 the carapace has a small supraorbital spine, and 

 the anteroventral margin is smooth. Also, in 

 Stage I zoeae of S. arcuata, the antennule and 

 inner flagellum of the antenna have several setae 

 terminally. Both the antennule and inner anten- 

 nal flagellum of Stage I zoeae of .S. spinus and S. 

 lilljeborgii and Stage II zoeae of iS. phippsii have a 

 large seta terminally. Finally, Stage I zoeae of S. 

 lilljeborgii have posterolateral spines only on the 

 fourth abdominal somite; Stage I zoeae of S. 

 arcuata have posterolateral spines on both fourth 

 and fifth abdominal somites. 



Makarov (1967) described Stage I zoeae of two 

 unidentified species of Spirontocaris ("species A" 

 and "species B") from plankton of the western 

 Kamchatka Peninsula shelf. His zoeae can be 

 separated from Stage I zoeae of S. arcuata by 

 the relatively long rostrum in his species A and 

 B. In addition, Makarov's Stage I zoeae of Spi- 

 rontocaris sp. B are longer than those of S. arcuata 

 (5.1 mm and 4.2 mm, respectively) and have 

 pleopodal buds. 



Ivanov (1971) briefly described four zoeae he 

 assumed were S. spina intermedia. His zoeae are 

 readily distinguishable from zoeae of S. arcuata 



437 



