DESCRIPTION OF LARVAE OF A HIPPOLYTID SHRIMP, LEBBEUS 

 GROENLANDICUS, REARED IN SITU IN KACHEMAK BAY, ALASKA 



Evan Haynes^ 



ABSTRACT 



Larvae of Lebbeus groenlandicus , a hippolytid shrimp, were reared in situ in Kachemak Bay, Alaska, 

 from the first zoea (Stage I) through themegalopa (Stage III). Each of the three stages is described and 

 illustrated, and then compared with descriptions of larvae of Lebbeus spp. given by other authors. 



Information on the larval stages of the genus Leb- 

 beus is meager. Pike and Williamson (1961), in 

 their summary of the generic characteristics of 

 Spirontocaris and related genera, note that the 

 only larva o^ Lebbeus known for certain is a larva 

 of L. polaris dissected from a well-developed egg. 

 During studies on rearing larvae of pandalid 

 shrimp for descriptive purposes (Haynes 1976, 

 1978), I succeeded in rearing larvae of L. groen- 

 landicus to the megalopa stage. This report de- 

 scribes and illustrates each of the two zoeal stages 

 and megalopa of L. groenlandicus , and compares 

 the stages obtained from rearing in situ and from 

 plankton in Kachemak Bay with provisionally 

 identified larvae of L. groenlandicus reported by 

 other authors. 



METHODS 



A complete discussion of rearing technique, 

 methods of measurement, techniques of illustra- 

 tion, and nomenclature of gills and appendages is 

 given by Haynes (1976). Briefly, the rearing 

 technique consists of obtaining Stage I zoeae from 

 known parentage in the laboratory and then rear- 

 ing the zoeae to postlarvae in 500-ml flasks sus- 

 pended upright beneath the surface of the sea. 

 Cast skins and larvae removed from the flasks 

 were examined in the laboratory to determine 

 sequence and morphology of each stage. Larval 

 stage was also verified using larvae from plankton 

 reared in the same manner as larvae obtained in 

 the laboratory. 



In the illustrations (Figures 1-3), for clarity, 

 setules on setae are usually omitted but spinulose 



'Northwest and Alaska Fisheries Center Auke Bay Labora- 

 tory, National Marine Fisheries Service, NOAA, P.O. Box 155, 

 Auke Bay, AK 9982L 



Manuscript accepted November 1977. 

 FISHERY BULLETIN: VOL. 76, NO. 2, 



setae are shown. The terms are defined as follows: 



setose - set with bristles (setae) 

 spinose - bearing many spines 

 spinous - spinelike 

 spinulose - set with little spines. 



The figures are in part schematic and represent 

 typical setal counts. 



STAGE I ZOEA 



Total length of Stage I (Figure lA) 6.9 mm 

 (range 6.4-7.4 mm; 10 specimens). Live specimens 

 characterized by bright orange color extending 

 along ventral surface of body from antennules to 

 fourth abdominal segment, orange gut, small 

 orange chromatophore at anus, and greenish in- 

 ternal thoracic organs; remainder of zoea trans- 

 lucent. Rostrum slightly sinuate, without teeth, 

 about two-thirds length of carapace. Carapace 

 with dorsal rounded prominence at base of ros- 

 trum and near posterior edge; no supraorbital 

 spines. Usually at least two minute spinules occur 

 along ventral margin of carapace immediately 

 posterior to pterygostomian spine. 



ANTENNULE (FIGURE IB).— First antenna, or 

 antennule, consists of an unsegmented cylindrical 

 basal portion and two distal conical projections; 

 largest conical projection bears four aesthetascs of 

 various lengths; smallest conical projection bears 

 a single heavily plumose seta. 



ANTENNA (FIGURE IC).— Consists of inner 

 flagellum (endopodite) and outer antennal scale 

 (exopodite). Flagellum two-segmented, about 

 twice length of scale; distal segment styliform and 

 terminating in narrow projection. Two simple 



457 



1978. 



