HAYNES: EARLY ZOEAL STAGES OF LITHODID CRABS 



Brief descriptions and comparisons of previous- 

 ly described lithodid zoeae follow. 



Cryptolithod.es typicus. — Based on the descrip- 

 tion by Hart (1965), Cryptolithodes typicus zoeae 

 are markedly different morphologically from 

 other described lithodid zoeae. In C. typicus 

 zoeae, the carapace lacks posterolateral spines in 

 all stages, the proximal expansion of the maxilla 

 is present in Stage II, and the telson does not 

 have a medial posterior invagination. In all other 

 lithodid zoeae, the carapace has posterolateral 

 spines in all stages, the proximal expansion of the 

 maxilla is absent until Stage IV, and the telson 

 has a medial posterior invagination. The large 

 eyes of C. typicus, however, are typical of zoeae of 

 the Pagurinae, and the absence of posterolateral 

 spines on the carapace is similar to zoeae of some 

 species of the Diogenidae. The shape of the telson, 

 the fused abdominal somite 6 and telson in Stages 

 III and IV, and the absence of uropods in C. 

 typicus are characters similar to those of some 

 porcellanid zoeae. 



Hapalogaster grehnitzkii , Dermaturus mandtii, 

 and P. brevipes. — Makarov (1967) briefly de- 

 scribed larvae collected off west Kamchatka that 

 he provisionally identified as Hapalogaster greh- 

 nitzkii, based on distribution of adults. Zoeae 

 of H. grehnitzkii are morphologically similar to 

 zoeae of Dermaturus mandtii and Paralithodes 

 brevipes but can be distinguished by length of the 

 posterolateral spines on abdominal somites 3-5. 

 In zoeae of H. grehnitzkii , posterolateral spines 

 on somites 3 and 4 are short (slightly longer than 

 the denticles that fringe the posterior margin), 

 and the posterolateral spines on somite 5 are 

 shorter than the width of somite 5. In zoeae of D. 

 mandtii and P. brevipes, posterolateral spines on 

 somites 3 and 4 are long (at least twice the length 

 of the denticles), and posterolateral spines on 

 somite 5 are longer than the width of somite 5 

 (Kurata 1956). 



Based on Kurata's (1956) brief descriptions, 

 zoeae of P. brevipes can be distinguished from 

 zoeae of D. mandtii by size of the carapace and 

 morphology of the antenna. Paralithodes brevipes 

 zoeae are slightly larger (carapace length, 1.4-1.7 

 mm) than D. mandtii zoeae (carapace length, 1.2- 

 1.4 mm). The antennal fiagellum of P. brevipes 

 zoeae is noticeably longer than the antennal scale 

 (including distal spine), and the antennal scale is 

 about nine times as long as wide. The antennal 

 fiagellum and antennal scale of D. mandtii zoeae 



are about the same length, and the scale is not 

 more than five times as long as wide. 



Hapalogaster mertensii. — Larvae of Hapalogast- 

 er mertensii were collected from ovigerous fe- 

 males at Fidalgo Island, Wash., and then reared 

 and described by Miller and Coffin (1961). Unfor- 

 tunately, their description is brief and lacks de- 

 tail and, therefore, has limited value. Apparently, 

 the only characters useful for distinguishing H. 

 mertensii zoeae from zoeae of other lithodid spe- 

 cies are size and number of setae on the antennal 

 scale. In zoeal Stages I-III of H. mertensii, the 

 antennal scale has six setae and, in Stage IV, four 

 setae. In all stages of H. mertensii, the setae are 

 markedly short (<Vi scale width) and lightly 

 plumose. In most other lithodid zoeae, the anten- 

 nal scale in Stage I has more than six heavily 

 plumose setae that increase in number in later 

 stages, and the setae are as long as, or longer 

 than, the width of the antennal scale. 



Lithodes aequispina. — Larvae of Lithodes aequi- 

 spina were reared and described from ovigerous 

 females collected in waters of southeastern Alas- 

 ka (Haynes 1982). Zoeae of L. aequispina are 

 most similar to zoeae of Paralithodes camtschat- 

 ica and P. platypus but can be readily distin- 

 guished from their zoeae by the number of tel- 

 sonic spines and the manner in which the third 

 (longest) pair of telsonic spines is attached to the 

 telson. In L. aequispina . the telson has 5:11 pairs 

 of telsonic spines, and the third pair of spines is 

 fused to the telson. In P. camtschatica and P. 

 platypus zoeae, the telson has ^ 8 pairs of telsonic 

 spines, and the third (longest) pair of spines is 

 jointed with the telson. 



Paralithodes brevipes, P. camtschatica, and P. 

 platypus. — Larvae of Paralithodes brevipes, P. 

 camtschatica, and P. platypus have been described 

 (Marukawa 1933; Kurata 1956, 1960, 1964; Hoff- 

 man 1958; Sato 1958; Makarov 1967). Zoeae of P. 

 brevipes can be distinguished from zoeae of P. 

 camtschatica and P. platypus by several charac- 

 ters. In P. brevipes zoeae, posterolateral spines on 

 the carapace are short and ventrally curved, the 

 dorsal posterolateral margin of the carapace is 

 convex, the rostrum is short (about equal to the 

 length of the antennal fiagellum), and the telson 

 has (excluding the hairlike process) six pairs of 

 spines in Stage I and seven pairs of spines in 

 Stages II-IV. In contrast, zoeae of P. camtschatica 

 and P. platypus have long, posterolateral spines 



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