EARLY ZOEAL STAGES OF PLACETRON WOSNESSENSKII AND 



RHINOLITHODES WOSNESSENSKII (DECAPODA, ANOMURA, 



LITHODIDAE) AND REVIEW OF LITHODID LARVAE OF 



THE NORTHERN NORTH PACIFIC OCEAN 



Evan B. Haynes 1 



ABSTRACT 



Stage I zoeae of Placetron wosnessenskii , and Stage I and Stage II zoeae of Rhinolithodes wosnes- 

 sensku , which were reared in the laboratory, can be distinguished from other described zoeae of 

 Lithodidae: P. wosnessensku have long, blunt spines on posterior margins of abdominal somites 2-5 

 and sinuate curvature of long, blunt, posterolateral spines on abdominal somite 5; R. wosnessensku 

 zoeae have a spine in the middorsal, posterior portion of the carapace. Zoeae of Lithodidae can be 

 distinguished from zoeae of Pagunnae by body shape, size of the eyes, spines on the carapace, devel- 

 opment of uropods, and presence or absence of the anal spine. Stages of lithodid zoeae can be distin- 

 guished by eye attachment, number of natatory setae on maxillipeds, and development of pleopods, 

 uropods. and telson. Keys, based on spination of the carapace, rostrum, abdomen, and telson, distin- 

 guish between zoeae and glaucothoe of each described species of Lithodidae from the northern North 

 Pacific Ocean. 



Crabs of the family Lithodidae constitute a major 

 component of the reptant decapod fauna of the 

 northern North Pacific Ocean. Of about 25 species 

 of Lithodidae in the northern North Pacific Ocean, 

 larvae have been described, at least in part, 

 for eight species: Dermaturus mandtii Brandt, 

 Cryptolithodes typicus Brandt, Hapalogaster 

 grebnitzkii Schalfeew, H. mertensii Brandt, Lith- 

 odes aequispina Benedict, Paralithodes breuipes 

 (Milne Edwards and Lucas), P. camtschatica 

 (Tilesius), and P. platypus Brandt. Most descrip- 

 tions are scattered in foreign scientific journals, 

 however, and published reviews of the larvae are 

 limited in species and scope. This report describes 

 and illustrates Stage I zoeae of Placetron wosnes- 

 sensku Schalfeew and Stages I and II zoeae of 

 Rhinolithodes wosnessenskii Brandt reared in the 

 laboratory from ovigerous females. I characterize 

 the morphological differences between zoeae of 

 the Lithodidae and subfamily Pagurinae (family 

 Paguridae), compare the morphology of lithodid 

 larvae of the northern North Pacific Ocean, and 

 provide keys for identifying the described larvae 

 to species and stage. 



'Northwest and Alaska Fisheries Center Auke Bay Labora- 

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

 210155. Auke Bay, AK 99821. 



Manuscript accepted October 1983. 

 FISHERY BULLETIN: VOL. 82. NO. 2, 1984. 



METHODS AND RESULTS 



In March 1982, ovigerous females of Placetron 

 wosnessenskii and Rhinolithodes wosnessenskii 

 were collected near Auke Bay, Alaska, in traps 

 and by divers using scuba. The females were 

 transported to the laboratory and kept in filtered 

 seawater (about 6°C) until the zoeae hatched 

 about 1 wk later. After hatching, about 50 zoeae of 

 each species were transferred to each of four 4 1 

 glass jars containing about 2,500 ml of seawater at 

 6.1° C. Seawater in the jars was changed about 

 every other day. Zoeae were fed live plankton 

 strained through a 0.333 mm mesh. About 10 ml of 

 live plankton was added to each jar every other 

 day. The live plankton consisted mostly of phyto- 

 plankton and barnacle nauplii. A more detailed 

 description of the rearing system and type and 

 duration of illumination is given in Haynes and 

 Ignell (1983). 



Zoeae of Placetron wosnessenskii hatched at 

 night, and samples of zoeae were taken the follow- 

 ing morning. No prezoeae of P. wosnessenskii 

 were seen. Rhinolithodes wosnessenskii zoeae 

 hatched at night and during the day, and those 

 examined about 10 min after hatching had rem- 

 nants of prezoeal exuviae attached to the cephalo- 

 thorax and telson. The remnant exuviae are not 

 described in this paper. 



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