| First stage: 5 mm long and very slender; faint pink tinge on the anterior side of the eye and in both pairs of antennae there is a faint pink tinge; few small red chromatophores about the mouth, at the base of the third maxillipeds, and two at the posterior end of the cephalothorax; otherwise the larva is quite transparent and colourless; rostrum is very slender, spiniform, and without denticles; eyes are immobile; antennule similar to that of P. danae except that there is a small joint between the little projection representing the inner flagellum and the stem; antenna has an undivided basal portion, and a scale bearing fifteen plumose setae; flagellum is shorter than the scale and is merely an undivided conical process tipped by a simple seta; incisor processes of both mandibles bear two teeth ;two teeth between the incisor and molar processes of the right mandible, and none in the same position on the left; basipodite of the first maxilla has five ordinary simple setae at the tip instead of the short stout ones found in the other species; exopodite of the second maxilla only bears eight to ten long simple setae, and has no trace of a proximal expansion; three pairs of maxillipeds only differ from those of P. danae in having slightly fewer setae; main difference between this larva, and the first stage larva of any other known British Columbian pandalid lies in the poor development of the pereiopods; first pereiopod is a biramous appendage, but the two rami are quite simple curved bars; other
four pereiopods are very similar to the first, but, while the second and third are also biramous, the fourth and fifth are uniramous. Second stage: about 7 mm long, a supra-ocular spine over each eye; eyes are stalked; antennule has a three-jointed stem and the outer flagellum has two groups of "olfactory" setae; antenna has two segments in the flagellum; first maxilla has about nine coarse setae on the basipodite; proximal expansion of the exopodite on the second maxilla is just appearing, much as in the first stage of P. danae; no essential change in the maxillipeds, although the second has gained a distinctly segmented endopodite; pereiopods are all segmented, although the joints in the fifth are very indistinct; exopodites bear plumose setae; pleopods have appeared as simple buds; telson is still indistinctly divided from the sixth segment, but otherwise it is very similar to that of a sedond stage P. danae larva. Third stage: 8 to 9 mm long; rostrum usually has two little teeth at the base; flagellum of the antenna is longer, but little changed; first maxilla resembles that of a first stage P. danae larva; epipodite of the second maxilliped is slightly bilobed; pereiopods are all longer in proportion to the body and definitely jointed; propodite of the second pereiopod is slightly expanded, showing the beginning of a claw; tiny buds of pleurobranchiae are visible at the bases of the pereiopods; epimeral plates are forming on the segments of the abdomen; telson is distinctly divided from the sixth abdominal segment; uropods are free, but the tail-fan is less well developed than in the third
stage of P. danae, since the telson is still very broad at the tip and the inner ramus of the uropod is much smaller than the outer. Fourth stage: 9 to 10 mm in length, but is really very similar to the third stage larva; four small dorsal spines at the base of the rostrum; mouth parts and pereiopods are all a little more developed than in the third stage, but there is no essential change; pleopods are distinctly biramous, but have no joints or setae; greatest change is in the tail-fan; both rami of the uropods are well developed; telson has the sides almost parallel, and has five pairs of setae at the tip, and three pairs up the sides. Fifth stage: 14 mm long; rostrum has 11 or 12 spines, of which 4 or 5 are on the carapace; flagellum of the antenna is fairly long and
jointed throughout its length; exopodite of the second maxilla has been steadily developing, small epipodite on the second maxilliped and its endopodite is considerably stouter; third maxilliped, the ischiopodite and meropodite have fused, and the bud of the mastigobranchia is present; mastigobranchiae are also appearing on the first four pereiopods; second pereiopod has a claw about as well developed as in the fourth stage of P. danae; pleopods have distinct joints and a few setae but no appendices internae; telson is a little narrower towards the tip than in the fourth stage. Sixth stage: rostrum has 14 dorsal teeth and 1 near the acute tip; flagellum of the antenna very similar to that of a fourth stage P. danae; mandibles are still only slightly different from those of the first stage, but through the skin the next stage mandibles can be seen and will evidently have both processes and the palp well developed; two small buds of arthrobranchiae are present at the base of the third maxilliped; pereiopods are a little longer proportionately, and the claw of the second is quite well developed, but otherwise the first and second are still more larval than adult in character; exopodite of the third pereiopod was
broken; all pleurobranchiae are quite well developed but there are still no arthrobranchiae in connection with the pereiopods; pleopod.s are much larger than in the fifth stage, have a few more small setae, and the appendices internae are present on the second to the fifth; first pleopod has the inner ramus much smaller than the outer; telson has four pairs of lateral spines, and five pairs of terminal spines; middle pair of terminal spines are much longer, and the next three pairs are beginning to disappear. |