FISHERY BULLETIN: VOL. 83. NO. 3 



exceptions, Key I can be used to identify larval 

 stages of Pandalus hypsinotus, P. danae, and P. 

 stenolepis. The exceptions are in Stage III P. hyp- 

 sinotus, the endopodite of the uropods is setose and 

 nearly the same length as the exopodite, and in 

 Stage III P. danae and P. stenolepis, the endopodite 

 is setose and somewhat shorter than the exopodite. 



Key I. — Generalized key to stages of most species of 

 pandalid. hippolytid, and crangonid larvae described 

 from waters of the northern North Pacific Ocean. 

 (This key cannot be used for all species, see Table 2 for 

 exceptions.) 



1 . Uropods absent 2 



Uropods present 3 



2. Eyes sessile; telson with 7 + 7 setae. . . . Stage I 

 Eyes stalked; telson with 8 + 8 setae . . Stage II 



3. Posterior width of telson about twice its 

 anterior width. Endopodite of uropod (Fig. 

 1 0, en) with relatively few setae and 

 noticeably shorter than exopodite (Fig. 1 0, 



ex) Stage III 



Posterior width of telson noticeably less than 

 twice its anterior width. Endopodite of 

 uropod setose and about as long as exopodite 

 Stage IV and later 



LARVAL CHARACTERS OF FAMILIES 



Crangonid larvae are relatively easy to distinguish 

 from pandalid or hippolytid larvae; however, pan- 

 dalid and hippolytid larvae often are difficult to 

 distinguish from each other, especially in the early 

 stages. Briefly, the characteristics of crangonid lar- 

 vae are 1) the tip of the antennal scale is always 

 unsegmented, 2) the inner flagellum of the antennule 

 is a setose spine or oblong projection, 3) an exopodite 

 is usually only on pereopod 1 and never on pereopods 

 3-5, and 4) in later stages, pereopod 1 is subchelate, 

 and the telson widens posteriorly. No known pan- 

 dalid or hippolytid larvae possess this combination of 

 characters. 



The following set of characters, although not with- 

 out exceptions, is probably the most useful set for 

 distinguishing between pandalid and hippolytid lar- 

 vae of the northern North Pacific Ocean. Pandalid 

 larvae 1) always have a long rostrum (greater than 

 1/4 carapace length) that has teeth from Stage III 

 on, 2) the basipodite of the maxillule has a subter- 

 minal seta, 3) exopodites are only on pereopods 1-2 



or 1-3, 4) the abdomen lacks posterolateral spines, 

 and 5) an anal spine is absent in Stage I. On the other 

 hand, hippolytid larvae 1) have a rostrum that is long 

 and without teeth (especially from Stage III on), 2) in 

 all stages, the basipodite of the maxillule lacks a sub- 

 terminal seta, 3) exopodites are on pereopods 1-2, 

 1-3. or 1-4 (rather than only on pereopods 1-2 or 1-3), 

 4) the abdomen has posterolateral spines, and 5) an 

 anal spine is present in Stage I (except larvae of the 

 genus Hippolyte). 



Late-stage (Stage IV and later) pandalid and 

 hippolytid larvae can often be distinguished from 

 each other by shape of eyes and distance between 

 bases of antennules. The eyes of pandalid lai-vae 

 taper toward the base, and the distance between 

 bases of antennules is more than the width of an 

 antennule. The eyes of hippolytid larvae are almost 

 cylindrical, and the distance between antennules is 

 less than the width of an antennule. In Stages I-III, 

 distinctions in the shape of eyes and distance be- 

 tween bases of antennules are usually not useful. 



Shape of the larva is often helpful in distinguishing 

 between pandalid and hippolytid larvae during the 

 initial sorting. Pandalid larvae, when viewed lateral- 

 ly, have nearly straight antennules, whereas the 

 antennules of many hippolytid larvae curve upward. 

 The abdomen of pandalid larvae appears slightly 

 longer than the abdomen of hippolytid larvae in rela- 

 tion to length of the larva as a whole. These two 

 characters are difficult to quantify and are best 

 learned through examination of specimens of known 

 identity. Additional morphological characters that 

 distinguish larvae of the Pandalidae, Hippolytidae, 

 and Crangonidae are given in the synopsis of each 

 family. 



PANDALIDAE 



(Genera Pandalopsis and Pandalus) 



In all stages, rostrum long, styliform, or slightly 

 sinuate; plumose seta on inner tlagellum of anten- 

 nule (Fig. IB, A|, if); maxillule with or without 

 subterminal seta (Fig. IF', Mx,, st) on basipodite; ab- 

 domen without dorsal spines, keels, or posterolateral 

 spines; pereopod 1 never subchelate. In Stage I, 

 supraorbital spine absent; rostrum with teeth in 

 some species; anal spine absent in some s})ecies. In 

 early stages of most species, antennal scale seg- 

 mented at tip. In Stages I and 11 of some species with 

 abbreviated development, vestigial exopodites on 

 pereopods 1 and 2 or 1-3. In later stages, developed 

 exopodites on pereopods 1 and 2 or 1-3, never on 1-4; 

 setose setae on endopodite of each pleopod (Stage V 



264 



