HAYNES: EARLY ZOEAL STAGES OF HIPPOLYTIDAE 



Pleopods. — Absent. 



Abdomen and telson (Figure 8A, E). — Abdomen 

 similar in shape to abdomen of Stage I E. suckleyi 

 except without spines or spinules. Telson emar- 

 ginated, bears 7+7 relatively long densely 

 plumose setae: longest (fifth) pair about three- 

 fourths length of greatest telsonic width. Minute 

 spinules along terminal margin of telson and 

 at base of each seta to fifth setal pair. Anal 

 spine present. 



COMPARISON OF ZOEAL STAGES 



WITH DESCRIPTIONS BY 



OTHER AUTHORS 



In the literature, authors have identified or 

 assigned names or stages to hippolytid larvae 

 obtained from plankton. A comparison of their 

 descriptions with my descriptions of zoeae of 

 known parentage is useful in placing these earlier 

 works in proper perspective (Table 2). 



Table 2. ^Presumed and corrected identities of hippolytid 

 zoeae discussed in this report. 



Lebbeus polaris 



Krpyer (1842, in Pike and Williamson 1961) 

 described an advanced embryo of L. polaris with 

 all appendages, except uropods, present and seg- 

 mented. The fourth and fifth abdominal somites 

 each have a pair of small posterolateral spines. 



All three pairs of maxillipeds have natatory 

 exopodites, but the pereopods have none. As far as 

 can be compared, my Stage I zoeae of L. polaris are 

 identical to Krpyer's embryo, except the pereopods 

 and pleopods of my specimens are unsegmented. 



Stephensen, in 1916, described a zoea from 

 southern waters of Greenland that he assumed is a 

 Stage I zoea of S. polaris (= L. polaris). As noted 

 by Pike and Williamson (1961), Stephensen's zoea 

 is similar to Krpyer's specimen. Stephensen's 

 zoea has posterolateral spines on the fourth and 

 fifth abdominal somites, lacks exopodites on the 

 pereopods, and the appendages are larger and 

 more developed than Krpyer's specimen. The 

 carapace of Stephensen's zoea has supraorbital 

 spines, and developing uropods are visible inside 

 the telson. In addition, the chelae of the first and 

 second pereopods of Stephensen's zoea are well 

 developed; the carpopodite of the second pereopod 

 had begun to develop joints; and the pleopods have 

 well-developed appendices internae. The presence 

 of appendices internae, well-developed chelae, 

 and segmentation of carpopodite shows that 

 Stephensen's zoea is in the last, or perhaps 

 penultimate, zoeal stage and that the species 

 passes through only three or, perhaps, four zoeal 

 stages. Under the name " Spirontocaris -larva 

 No. 1," Stephensen (1935) included several speci- 

 mens collected from waters of western Greenland 

 that he assumes are later stages of S. polaris 

 (= L. polaris); one specimen bears exopodites 

 on pereopods 1 and 2. 



The characteristics of Stephensen's (1916) late- 

 stage "S. polaris" zoea are typical of Lebbeus 

 zoeae although his zoea differs somewhat from 

 my L. polaris zoeae. Stephensen's zoea has an 

 unsegmented antennal flagellum, and the telson 

 is fused with the sixth somite; my zoeae of L. 

 polaris have a two-segmented antennal flagellum 

 in Stage I, and the sixth somite and telson are 

 jointed in Stage II. If Stephensen was correct in 

 assuming his specimen to be L. polaris, then L. 

 polaris in Greenland waters has at least one more 

 zoeal stage than L. polaris in Alaskan waters. 

 Stephensen's (1935) descriptions of his "Spiron- 

 tocaris-\arva No. 1" zoeae are too brief to identify 

 either the species or stage. At least one of Stephen- 

 sen's specimens lacks the pair of spines on the 

 antennal protopodite and must be a species other 

 than L. polaris. 



Makarov (1967) briefly described zoeae collected 

 from plankton of the western Kamchatka Penin- 

 sula shelf. He thought these zoeae were probably 



435 



