FISHERY BULLETIN: VOL. 76, NO. 4 



fiable based on his incomplete descriptions and 

 rather stylized illustrations. 



Advanced development is implied in but one 

 galatheid, the cave-dwelling Munidopsis 

 polymorpha Koelbel 1892. This species is pres- 

 ently known only from a littoral cave formed by 

 lava tunnels which connect to the sea in the Ca- 

 nary Islands (Fage and Monod 1936). These au- 

 thors never found more than five, extremely large 

 (1.5-1.8 mm in diameter) eggs on an individual 

 female. No larval stages were described, but it was 

 hypothesized that the young Munidopsis was well 

 advanced in development inside the egg and prob- 

 ably hatched into a form nearly like the adult. 

 Given the rather unique habitat for a Munidopsis, 

 advanced development in M. polymorpha would 

 not be surprising. The vast majority of other 

 species of Munidopsis are deep-sea forms, most of 

 which occur below 500 m (Mayo 1974) in the At- 

 lantic Ocean, although some species occur in shal- 

 lower waters on the continental shelf. 



In summary, it is apparent that larval develop- 

 ment in the Galatheidae is quite diverse, includ- 

 ing advanced development (i.e., with imminent 

 metamorphosis) in the cave dwelling M. 

 polymorpha , abbreviated development with as few 

 as three larval stages (M. tridentata, Al-Kholy's 

 Galathea sp.?), to "normal" development of four- 

 five zoeal stages (e.g., Munida, Galathea). Sub- 

 stage intercalation is known in the genxx^Pleuron- 

 codes, but seems to be restricted to the fourth, or 

 penultimate, ecdysial stage. Intercalation of a 

 sixth zoeal stage, perhaps only a laboratory ar- 

 tifact, is also known in one species of this genus. 

 Skipped stages appear only in two species of 

 Galathea, and perhaps one of Munida, at present, 

 and these result in the elimination of regular zoeal 

 stages IV and V and their replacement by an ad- 

 vanced stage IV which subsequently molts di- 

 rectly to megalopa. 



Developmental variation such as that just dis- 

 cussed allows some interesting speculation as to 

 its evolutionary consequences in view of the fact 

 that the phylogenetically closely related anomu- 

 ran family Porcellanidae generally undergo a re- 



■"The term "direct" development is restricted in this paper to 

 those larvae which hatch from the egg in a form morphologically 

 similar to the adult and undergo no further metamorphosis. 

 Larvae exhibiting "advanced" development usually hatch in the 

 penultimate or ultimate zoeal stage and thus may undergo addi- 

 tional ecdysis prior to metamorphosis. Larvae with "ab- 

 breviated" development hatch as early zoeae (often with a pre- 

 zoeal or first zoeal stage present), but may dispense with one or 

 more intermediate stages in completing their larval develop- 

 ment. 



duced developmental sequence of usually no more 

 than two zoeal stages. These stages appear to be 

 morphologically equivalent in most respects to 

 Galathea stages I and IV, sensu lato. Substages 

 have been postulated for some porcellanid larvae, 

 notably Indo-Pacific species, but are not positively 

 known to occur in Atlantic and eastern Pacific 

 species. Previously postulated substages in Atlan- 

 tic species have been shown to be the result of 

 accelerated morphological development without 

 an ensuing molt and have been seen primarily in 

 larvae collected from the plankton (Gore 1968 and 

 others). However, the larvae of the western Pacific 

 genus Petrocheles apparently do reflect their 

 galatheid ancestry by undergoing five zoeal stages 

 during development. Morphological features of 

 the telson, uropods, and antennal scale in these 

 larvae all resemble, to a greater or lesser degree, 

 their counterparts in larvae of Galathea and 

 Munida (Wear 1965). Further studies along these 

 lines should be most interesting and productive. 



DESCRIPTION OF 

 THE LARVAE 



First Zoea 



Carapace length: 1.0 mm. 



Number of specimens examined: 10. 



Carapace: (Figure 2A, a). Typically galatheid, 

 somewhat inflated; rostral spine horizontal, little 

 expanded proximally, straight, extending to level 

 of scapherocerite spine, or slightly beyond, about 

 0.5 X carapace length(CL), unarmed; posterolat- 

 eral carapace margins armed with a series of 

 about 15 small denticles placed before large, pos- 

 terior spine; latter slightly more than 0.1 x CL; 

 dorsomedial carapace margin excavated, with 

 about 13 small denticles along sinus margin. Two 

 small setae medially above eyes; latter sessile. 



Antennule: (Figure 3A). A simple rod, both en- 

 dopodite and exopodite fused to protopodite; 

 former with 1 elongate plumose seta, latter with 3 

 aesthetascs and 3 setae. 



Antenna: (Figure 3B). Endopodite rodlike, 

 about 0.4 X scaphocerite length, fused to protopo- 

 dite, a single distinct spine at its tip, plus a long 

 plumose seta; scaphocerite usually with 9 setae 

 along margin, tip produced into long daggerlike 

 spine about 0.3 x total scale length; protopodite 



788 



