HAYNES: DESCRIPTION OF PANDALUS BOREALIS LARVAE 



from either her description or figure of ventral 

 teeth on the rostrum, and the pleopods have not 

 yet developed appendices internae. In my Stage V 

 zoeae the rostral tip always bears at least a pro- 

 tuberance indicative of the bifid tooth, and 

 pleopods 2-5 bear at least partially developed ap- 

 pendices internae. In contrast to my Stage VI, the 

 megalopa, Berkeley's Stage VI is still typically 

 zoeal: there is still no mention of ventral rostral 

 teeth, the carapace still bears a supraorbital spine, 

 the carpopodites of the second pereopods are not 

 segmented, and the telson bears three pairs of 

 lateral spines (not including the sixth terminal 

 pair) and terminal setal pairs 2-4 have begun to 

 degenerate. 



Berkeley (1931) also mentioned a P. borealis 

 larva she obtained from plankton that, according 

 to her. corresponds to the sixth stage of P. danae 

 Stimpson and is similar to that described by Sars 

 (1900) as the "post-larval" stage of P. borealis. 

 Berkeley's sixth stage and Sars' "post-larval" 

 stage are typically nonzoeal as indicated by the 

 lack of supraorbital spines, segmentation of the 

 carpopodites of the second pereopods, degenera- 

 tion of the pereopodal and third maxilliped exopo- 

 dites, and the typically adult shape and spination 

 of the telson. Because this stage would be at least 

 the seventh stage, it appears that P. borealis in 

 British Columbia waters, as well as Greenland 

 waters (Stephensen 1916), has at least six zoeal 

 stages compared with only five zoeal stages in 

 Alaska waters. 



The preceding comparisons show that Berke- 

 ley's zoeae were less well developed at each given 

 stage than mine and an additional stage or two 

 was probably necessary for her zoeae to reach the 

 megalopa stage. An apparent contradiction to this 

 delayed development is the lack of segmentation 

 of the antennal scale in the early stages of Berke- 

 ley's zoeae. As shown by Haynes (1976), however, 

 Berkeley was mistaken in this regard and her 

 specimens undoubtedly possessed a segmented 

 scale in the early stages. 



The only other description of larvae of P. 

 borealis known to me is that of Kurata ( 1964) who, 

 like Berkeley 1 1931 ), obtained Stage I zoeae in the 

 laboratory from known parentage but Stages 

 II-VII from plankton. Kurata's zoeae are essen- 

 tially identical to mine through Stage V, except 

 the rostrum of Kurata's Stage V zoeae is iden- 

 tical to the rostrum of my Stage IV zoeae. Kurata's 

 Stage VI corresponds to my Stage V, but his Stage 

 VII possesses characteristics intermediate be- 



tween my Stages V and VI. For instance, in Kura- 

 ta's Stage VII the exopodites on pereopods 1-3 and 

 the third maxilliped have not begun to degenerate 

 nor are the carpopodites segmented whereas in my 

 Stage VI (megalopa) the exopodites on pereopods 

 1-3 and the third maxilliped are reduced and the 

 carpopodites of the left and right second pereopods 

 are segmented. Also, the lateral spination and 

 shape of the telson of Kurata's Stage VII are typi- 

 cal of postzoeae but posteriorly the telson bears 

 6 + 6 spines, a typically zoeal characteristic. By 

 studying Stage VII individuals just prior to molt- 

 ing, Kurata found that Stage VIII individuals pos- 

 sessed a distinct mandibular palp and degenera- 

 tion of posterior telson spines 2-4. He concluded 

 that Stage VII was the last zoeal stage and Stage 

 VIII the first postzoea, or megalopa. 



According to Lebour (1930). the lack of an outer 

 seta on the maxillule in zoeae of Pandalus is one 

 criterion for distinguishing this genus from cer- 

 tain other Caridea. Pike and Williamson (1964), 

 however, found the seta consistently present in 

 early stages of British species of Pandalus. Oc- 

 currence of the seta in Stage I zoeae has been 

 reported by Gurney ( 1942) for Pandalus montagui 

 Leach and P. stenolepis Rathbun; by Kurata 

 (1955, 1964) for P. borealis and P. kesslen Czer- 

 niavski; and Modin and Cox ( 1967) for P.jordani 

 Rathbun. I have consistently found the seta in the 

 early stages of P. hypsinotus, P. goniurus, and P. 

 borealis. Lebour's suggestion that the lack of the 

 seta is a distinguishing criterion for zoeae of Pan- 

 dalus should, therefore, be disregarded. 



In addition to P. borealis. larvae have been de- 

 scribed, at least in part, for nine other species of 

 pandalids from the North Pacific Ocean: P. 

 goniurus, P. jordani, P. platyceros Brandt, P. 

 danae, P. kessleri, P. hypsinotus, P. stenolepis, 

 Pandalopsis dispar Rathbun, and P. coccinata 

 Urita. Of these nine species, larvae of Pandalus 

 stenolepis, P. jordani. and P. goniurus are most 

 like larvae of P. borealis, being characterized by 

 exopodites on pereopods 1-3 rather than only on 

 pereopods 1 and 2 and by poorly developed 

 pereopods in Stage I. Zoeae of P. stenolepis were 

 described by Needier ( 1938). Based on her descrip- 

 tions, zoeae of P. stenolepis are readily distin- 

 guished from zoeae of P. borealis by 1) the shape 

 and spination of the rostrum, which in Stage I P. 

 stenolepis is about as long as the carapace and 

 projects upward rather than downward as in P. 

 borealis, and 2) the fringed posterior edge of the 

 abdominal somites and the serrated margins of 



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