FISHERY BULLETIN; VOL. 83, NO. 3 



Figure 4. -Carapace, Stage I zoea of 

 Pandalopsis dispar. 



i 



1 . mm 



Rostrum horizontal; exopodites on pereopods 

 with natatory setae 2 



2. Uropods absent; length of larvae < 13.0 



mm Stage II 



Uropods present; length of larvae • 13.0 

 mm 3 



3. Endopodite of uropod noticeably shorter 

 than exopodite; length of larvae = 16.0 



mm Stage III 



Endopodite and exopodite of uropod same 



length; length of larvae > 16.0 mm 



Stage IV and later^ 



Genus Pandalus Leach 



Most species with unabbreviated development. In 

 all stages, thoracic appendages not especially long or 

 thin. In Stage I, larvae usually 5-6 mm long; rostrum 

 usually without teeth; pereopods usually undevelop- 

 ed and tucked under cephalothorax; telson with 7 -t- 

 7 setae; telson not jointed with abdominal somite 6. 

 In early stages of some species, anteroventral 

 margin of carapace with denticles; posterior margin 

 of abdominal somites with spinules. 



Pandalus borealis Kr<>yer' 



Six larval stages. 



•'A later larval stage, probably Stage V or VI, characterized by 

 rostrum with 25 dorsal spines: 1 spine near tip, 14 dorsal spines, 10 

 ventral spines. Chela of pererjjKxl 2 (Fig. 1, P^,, ch) developed, and 

 carpopodite (Fig. 1, ca) with a few faint segments; abdominal 

 somites and pleopods essentially adult; telson narrows posteriorly 

 and has 7 + 7 slightly plumose, terminal setae and 6 pairs of single 

 lateral spines. Length: .30.0 mm (Berkeley 1930). 



'Larvae of ParuidLuK harealia and Pandaliuf goniurus are often 



Stages I-V, VI (megalopa), and VII and VIII (ju- 

 veniles); all stages from both known parentage 

 and plankton; figures 1-7 in Haynes (1979). 



Stage I, known parentage; Stages II-VII from 

 plankton; figures 1-3 in Kurata (1964a). 



Stage I, known parentage; Stages II-VI from 

 plankton; figures 7 and 8 in Berkeley (1930). 



Stages I-V from plankton; described as "P. propin- 

 quus (?)" by Stephensen (1912); figures 22-31 in 

 Stephensen (1912). 



Stage III from plankton; described as "Spironto- 

 caris larva Nr. 4" by Stephensen (1916); figure 

 11 in Stephensen (1916). Also described as P. 

 propinquics, Stage VI? by Stephensen (1916); 

 figure 17 (chelae only) in Stephensen (1916). 



Stage IV from plankton; described as "Dynuis 

 typus" (?) by Kr0yer (1861, as cited in Stephen- 

 sen 1935). No figures. 



"Post larval" from plankton; Plate VII in Sars 

 (1900). Probably megalopa of P. borealis (see 

 Haynes 1979). 



Not Stages I-VIII P. borealis as described by Sars 

 (1900) and figured in Plates I-VI. Correct iden- 

 tity, Caridion gordoni (see Berkeley 1930; Le- 

 bour 1930). 



In all described stages, carapace and abdominal 

 somites not flared laterally; basipodite of maxillule 



found together in plankton. They are esf)ecially similar in the early 

 stages and are difficult to distinguish. For identification of these two 

 species, I have included Table 4, which lists by larval stage the most 

 readily observable differences for both species. In general, larvae of 

 P. goniuni.'i are smaller than those of P. horeiilin. In SUiges I-III, P. 

 goninruK larvae have fewer setae on the antennal scale and certain 

 mouth parts than /'. horeali.^ larvae. From Stage IV to megalo()a, 

 the rostrum of P. hureaU.^ has more dorsal teeth, pereopcni 2 is more 

 developed, and the pleopods are fringed with more setae than larvae 

 of P. jrowmrus (Haynes 1979). 



266 



