FISHERY BULLETIN: VOL 76, NO. 2 



lateral spine of proximal segment well developed. 

 Antennal flagellum with at least 30 segments; 

 about four times length of scale. Mandibles with 

 unsegmented palps bearing four or five short 

 teeth. Endopodite of maxillule reduced. Maxil- 

 lipeds shaped as in adult, exopodites reduced. Dac- 

 tylopodites of first and second pereopods well 

 developed; carpopodite of second pereopod six- 

 (sometimes seven-) segmented. Lateral margins of 

 pleopods fringed with setae; appendix internae 

 with minute cincinnuli. Posterolateral spines on 

 abdominal segments four and five remnant or 

 lacking. Telson (Figure 3B) rectangular in shape; 

 bears two pairs of spines terminally and one pair 

 laterally (one or two additional spines may occur 

 centrally on terminal margin). Uropods exposed; 

 fully developed except transverse hinge not com- 

 plete. 



COMPARISON OF LARVAL STAGES 



WITH DESCRIPTIONS BY 



OTHER AUTHORS 



Under the name "Spirontocaris-larva No. lA," 

 Stephensen (1935) included four specimens that 

 were morphologically identical to zoeae provi- 

 sionally identified by him as Stage I S. polaris 

 (= Lebbeus polaris (Sabine)) except that they dif- 

 fered by lacking spines on abdominal segments 

 four and five, exopodites on any pereopods, or free 

 uropods. He regarded these four zoeae as belong- 

 ing to either Spirontocaris groenlandica ( = L. 

 groenlandicus), S. gaimardii (= Euahis gaimar- 

 dii (H. Milne Edwards)), or S. spinas (Sowerby). 

 Pike and Williamson (1961) have shown that the 

 absence of spines on abdominal segments four and 

 five eliminates the zoeae from being either E. 

 gaimardii or S. spinus. They agree with Stephen- 

 sen that his specimens oC'Spirontocaris-larwa No. 

 lA" are closely allied to zoeae he tentatively de- 

 scribed earlier (Stephensen 1917, 1935) as S. 

 polaris (= L. polaris). They suggest, therefore, 

 that Stephensen's "Spirontocaris -larva No. lA" 

 probably belongs to the genus Lebbeus and spe- 

 cifically to L. groenlandicus. 



Comparison of my zoeae of L. groenlandicus 

 with the descriptions given by Stephensen for 

 "Spirontocaris-larva No. lA" shows that 

 "Spirontocaris -larva No. lA" are not zoeae of L. 

 groenlandicus. My Stage I zoeae bear remnant 

 exopodites on the first and second pereopods and 

 lateral spines on abdominal segments four and 

 five, but Stephensen's Stage I zoeae bear neither 



the exopodites nor the spines. My Stage I zoeae do 

 not bear supraorbital spines, the peduncle of the 

 antennule is without joints or a ventral spine, and 

 there is no indication of the carpopodite of the 

 second pereopod being jointed; Stephensen's Stage 

 I zoeae bear supraorbital spines, the peduncle of 

 the antennule is three-jointed and bears a distinct 

 ventral spine, and the carpopodite of the second 

 pereopod is partially jointed. In addition, the 

 chelae of the first and second pereopods are not as 

 well formed in my Stage I zoeae as they are in 

 Stephensen's Stage I zoeae. 



Several of the morphological characteristics de- 

 scribed by Stephensen as pertaining to "Spiron- 

 tocaris-larva No. lA" are typical of later stage 

 zoeae, a fact already noted by Pike and Williamson 

 ( 1961) in their discussion of the morphology of the 

 zoeae of L. polaris and which prompted them to 

 suggest that Stephensen's zoeae were actually in 

 the second, or penultimate, zoeal stage. Even if 

 Stephensen was mistaken in identifying his zoeae 

 as Stage I rather than Stage 11, the morphological 

 differences between my zoeae and his are too great 

 to consider them identical species. My Stage II 

 zoeae bear spines on abdominal somites four and 

 five and the telson is segmented from the sixth 

 abdominal somite, whereas Stephensen's zoeae do 

 not bear spines on abdominal somites four and five 

 and the telson is not segmented from the sixth 

 abdominal somite. Also, in my Stage II zoeae the 

 peduncle of the antennule does not bear a ventral 

 spine and is unsegmented but in Stephensen's 

 zoeae the peduncle bears a ventral spine and is 

 segmented. 



I have no further evidence on the identity of 

 Stephensen's "SpjVontocans-larva No. lA." Of the 

 three members of the genus recorded from Green- 

 land waters, L. polaris, L. groenlandicus, and L. 

 microceros (cf. Holthuis 1947; Squires 1966), L. 

 microceros was not recorded by Stephensen. Ap- 

 parently it is rare and its larvae have not been 

 described. Also, the advanced development of 

 Stephensen's "Spirontocaris-larva No. lA" makes 

 it unlikely that it belongs to another genus of the 

 spirontocarid group (cf. Pike and Williamson 

 1961). Apparently Stephensen's "Spirontocaris- 

 larva No. lA" is either the zoea of L. microceros or 

 that of another species of Lebbeus not yet recorded 

 from Greenland waters. 



On the basis of descriptions of "Spirontocaris- 

 larva No. lA" by Stephensen (1935) and a late 

 stage embryo of Hippolyte polaris ( = L. polaris ) by 

 Kr^yer (1842), Pike and Williamson (1961) 



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