FISHERY BULLETIN: VOL. 79. NO. 3 



zoeal Stages I-IV of a species o^ Lebbeus. He also 

 obtained one specimen each of "Lebbeus sp. D" 

 and "Lebbeus sp. C"; these he thought were zoeal 

 Stages I and II, respectively. My Stage I zoeae of 

 L. polaris are similar to Makarov's Stage I zoea 

 ("Lebbeus sp. D") except my zoeae are not as long 

 (average length 5.4 mm compared with 6.4 mm). 

 Makarov's Stage II zoea {"Lebbeus sp. C") is 7.6 

 mm long; the eyes are sessile; and the carapace 

 lacks supraorbital spines. My Stage II zoeae of L. 

 polaris are 5.7 mm (mean) long; the eyes are 

 stalked; and the carapace has supraorbital spines. 

 Development of Makarov's "Lebbeus sp. C" and 

 "Lebbeus sp. D" zoeae shows that they are un- 

 doubtedly zoeae of the genus Lebbeus. Because his 

 "Lebbeus sp. C" zoea has sessile eyes and does 

 not have supraorbital spines, it must be a Stage 

 I zoea rather than a Stage II zoea. "Lebbeus 

 sp. C," therefore, is a species different from 

 "Lebbeus sp. D." 



Larvae of only one other species o{ Lebbeus, L. 

 groenlandicus, have been completely described 

 from known parentage (see Haynes 1978). At 

 comparable zoeal stages, L. groenlandicus is more 

 developed than L. polaris. The antennal flagellum 

 of Stage I zoeae of L. groenlandicus is about twice 

 as long as the scale and terminates in a narrow 

 projection. In L. polaris, the antennal flagellum is 

 only slightly longer than the scale and has a 

 plumose seta and spine. Also, in Stage I zoeae of L. 

 groenlandicus, the epipodite of the first maxil- 

 liped is bilobed; the second maxilliped has a single 

 lobed epipodite; and pereopods and pleopods are 

 either partially or fully segmented. In L. polaris, 

 only the first maxilliped bears an epipodite (single 

 lobed), and none of the pereopods or pleopods are 

 either partially or fully segmented. 



In Stage II zoeae of L. groenlandicus, the 

 supraorbital spine is well developed; the anten- 

 nule differs considerably from the antennule of 

 Stage I; the antennal flagellum has setae; the 

 antennal scale is fringed with plumose setae along 

 nearly the entire inner margin; the pereopods are 

 essentially adult in shape; and the pleopods are 

 fully segmented. In Stage II L. polaris, the supra- 

 orbital spine is small; the antennule and antennae 

 are similar to the antennule and antennae of 

 Stage I; the pereopods are not adult in shape; and 

 the pleopods are unsegmented. 



Lebbeus groenlandicus has only three larval 

 stages: two zoeal stages and one megalopal stage 

 (Haynes 1978). Because larvae of L. polaris are 

 somewhat less developed for a given stage than 



those of L. groenlandicus , L. polaris probably has 

 three zoeal stages before molting to the megalopa. 



Eualus suckleyi 



Zoeal Stages I and II oiE. suckleyi are similar to 

 the same zoeal stages of .E. gaimardii (H. Milne 

 Edwards), S. spinus, and S. lilljeborgii (as Pike 

 and Williamson [1961] described them from east- 

 ern Atlantic specimens); however, there are slight 

 differences in setation, development of pereopods, 

 and armature of carapace and abdomen. The 

 antennal flagellum of Stage I zoeae of E. suckleyi 

 has a spine and a seta; the antennal scale has a 

 plumose seta at the base of each of the four 

 segments; and pereopods 1-5 are present (pere- 

 opods 1-3 biramous, other pereopods uniramous). 

 The antennal flagellum of Stage I zoeae of E. 

 gaimardii has only a spine; the antennal scale has 

 a small outer spine at the base of the four 

 segments; and pereopods 1-4 are present and 

 uniramous. Stage I zoeae of S. spinus and S. 

 lilljeborgii lack minute spines on the anteroven- 

 tral margin of the carapace, have a rudimentary 

 supraorbital spine, and only pereopods 1 and 2 are 

 biramous. Also, S. spinus has posterolateral 

 spines on abdominal somites 4 and 5 rather than 

 only on somite 5 as in £■. suckleyi. 



In Stage II zoeae of E. suckleyi, an outer 

 plumose seta is at the base of the distal joints of the 

 antennal scale; and exopodites on maxillipeds 1-3 

 have four, five, and five natatory setae, respec- 

 tively. In Stage II zoeae of E. gaimardii, a some- 

 what stout spine is at the base of the distal joints of 

 the antennal scale, and exopodites on maxillipeds 

 1-3 have five, seven, and seven natatory setae, 

 respectively. Stage II zoeae of both S. spinus and 

 S. lilljeborgii have a tuft of dorsal setae on 

 abdominal somite 4; Stage II zoeae of E. suckleyi 

 do not have this tuft. 



Eualus fahrkii 



Stephensen's (1916) "Spirontocaris-larva Nr. 3" 

 were the most abundant spirontocarid larvae 

 in his plankton samples from Greenland waters. 

 He thought the larvae were the same species 

 as the most abundant adult and described and 

 illustrated them as the "youngest" stage, "inter- 

 mediate" stage, and "oldest" ("last") stage of 

 Spirontocaris fabricii (= Eualus fabricii). Ste- 

 phensen (1935) later described additional charac- 

 teristics for the "first" and "last" stages. Frost 



436 



