CONOR and CONOR: LARVAE OF FOUR PORCELLANIDAE 



as in Turtox CMC-9AB and CMC-10 media.' 

 Drawings were made from both types of ma- 

 terial with the aid of a Wild M-20 compound 

 microscope and camera lucida attachment. 

 Since the length of the rostral and posterior 

 spines of zoeae is highly variable and dependent 

 on a number of factors, only the carapace proper 

 was measured to serve as an indication of zoeal 

 size. This measurement was made from the 

 point of junction of the posterior spines to the 

 posterior margin of the orbital arch, using an 

 ocular micrometer. 



The term "seta" is used to indicate any firm- 

 walled process, located on an appendage or other 

 body surface, which is distinctly articulate at 

 its base or attachment point (Figure 1). The 

 figures are in part schematic and represent typ- 

 ical setal counts only. Setules are not represent- 

 ed in actual numbers and are often omitted en- 

 tirely for clarity. Only one member of each 

 setal pair present is figured for the exopodites 

 of zoeal maxillipeds. Only the right member of 

 each appendage pair is figured except for man- 

 dibles, which are sometimes drawn in pairs from 

 the dorsal view. 



Sexually mature females of the two genera 

 considered in this study produce eggs of dis- 

 tinctly diflferent types. Pachycheles rudis and 

 P. pubescens females carry eggs which are 0.50 

 to 0.58 mm in size and brilliant yellow-orange 

 when they are newly extruded. The eggs of 

 P. rudis, as Knudsen (1964) and Knight (1966) 

 observed, gradually change to a translucent am- 

 ber color as the embryos develop and the yolk 

 is absorbed. The color change with development 

 is similar in P. pubescens. The age of the egg 

 masses of the individual females collected in the 

 field was unknown; however, the maximum 

 length of time any female P. rudis carried eggs 

 was 47 days, and two others carried eggs for 43 

 days before releasing larvae. This time may 

 approach the length of time eggs are carried in 

 this species. In both Pachycheles species, eggs 

 hatched and all the larvae were released in a 

 period of 10 to 20 hr. A hatch from a large 



Reference to trade names in the publication does not 

 imply endorsement of commercial products by the Na- 

 tional Marine Fisheries Service. 



female (carapace width 14.2-15.0 mm) may 

 yield between 2,000 and 3,000 larvae but brood 

 size varies (Knudsen, 1964). 



In contrast, the eggs of Petrolisthes cinctipes 

 and P. eriomerus are somewhat larger, 0.80 to 

 0.84 mm, and are deep scarlet to maroon in color, 

 when newly extruded, similar to those of other 

 species in the genus (Wear, r965b; Greenwood, 

 1965). As Boolootian et al. (1959) also ob- 

 served, the eggs gradually change to a translu- 

 cent brownish red color as the embryos develop 

 and the yolk is absorbed. Females of these two 

 species were deliberately collected close to the 

 hatching time; consequently, no information on 

 the length of the brooding period was obtained. 

 The time required for a female to complete a 

 hatch is similar in these two Petrolisthes species 

 but diflfers considerably from that observed for 

 the Pachycheles species. Female Petrolisthes 

 require 40 to 70 hr to release an entire group 

 of larvae in the laboratory. Release of the lar- 

 vae in these two species occurs in spurts with 

 "resting" periods between each period of con- 

 centrated release. 



The embryonic and larval histories of all four 

 species observed in the laboratory have a num- 

 ber of characteristics in common. Fully devel- 

 oped embryos examined prior to eclosion pos- 

 sessed the full complement of primary red 

 chromatophores found throughout the active 

 larval life of these crabs. Although occasional 

 minor variations were noted both in laboratory 

 hatches and in larvae from the plankton, the 

 occurrence and placement of the chromatophores 

 is generally stable and is species specific, as var- 

 ious workers have noted in other species (Wear, 

 1964a, b, 1965a, b; Greenwood, 1965; Gore, 1968; 

 Gurney, 1942). The primary chromatophores 

 can thus be used to identify a larva to the species 

 level at any stage of development. 



In the hatching of all four species, females re- 

 leased larvae in the form of prezoeae. This has 

 been observed in other porcellanid species, for 

 example, by Lebour (1943), Greenwood (1965), 

 Wear (1965b, 1966), and Gore (1968). The 

 duration of this stage in the laboratory varies 

 considerably and lasts from 10 min to about 1 hr 

 in the species studied here. Prezoeae were never 

 collected in the plankton. 



191 



