FISHERY BUI.LKTIN VOL 77. NO 2 



To provide evidence for this problem, the com- 

 plete larval development of A/, innltfrons. reared 

 under laboratory conditions, is described and il- 

 lustrated here. Larvae of M . nodifrons are com- 

 pared insofar as possible with descriptions of .W. 

 nu-rcenaria and M. rumphii . and features used in 

 separating the various larvae are noted. 



MATERIALS AND METHODS 



A 66.0 mm CW (carapace width) female with 

 bright orange eggs was collected from a sabellariid 

 worm. Phragmatopoma lapidosa, reef at Seminole 

 Shores, Martin County, Fla. (Gore et al. 1978) on 

 L5 June 1977. Ovigerous females were found from 

 May through August. The berried crab w^as re- 

 tained in a nonflowing marine aquarium at the 

 Smithsonian Institution, Fort Pierce Bureau, and 

 fed mullet, Mugil sp., strips daily. The egg mass 

 progressively darkened from bright orange to 

 dark brown until hatching on 26 June 1977. The 

 larvae were cultured in the laboratory using 

 methods developed by Costlow and Bookhout 

 ( 1960, 19621, Gore (1968), and Provenzano ( 1967). 

 Six 24-compartmented trays were used, and each 

 compartment contained three zoeae. Equal num- 

 bers of zoeae were reared inoceanic water (35%") at 

 20" C ( ±0.5 ) in constant light; at room tempera- 

 ture (range = 2r-26.5° C; x = 24.5° C) in diurnal 

 light: and at 30° C ( ±0.5°) in a constant tempera- 

 ture unit(CTU) in 12 h of light, 12 h of darkness. 

 Seawater in the trays was changed and zoeae were 

 fed freshly \\&\.c\\ed Arteinia salina nauplii daily. 

 The number of zoeae was reduced to one per com- 

 partment on completion of the molt to the second 

 zoeal stage. 



Throughout the course of larval development all 

 molts, dead zoeae. and some living representatives 

 were preserved in 70'/? ethanol. Usually 10 speci- 

 mens at each stage of development were dissected 

 and examined for moi-phological characters using 

 procedures described in studies by Gore (e.g.. 

 1968). In the description that follows the first four 

 zoeal stages of ^W. nodifruns are denoted as zoeae 

 one (Z I) to zoeae four (Z IV). However, the fifth 

 zoeal stage is discussed as either the penultimate 

 fifth stage (Z Vp) which molts to a sixth stage 

 before molting to megalopa, or the ultimate fifth 

 stage (Z Vu) which molts directly to megalopa. 

 Both fifth stages possess pleopods, appendages 

 that typically develop in the stage preceding 

 megalopa. Because there are few morphological 

 differences between the penultimate and ultimate 



fifth stages, as noted in the larval descriptions, 

 they are each considered one stage, and not sub- 

 stages. The sixth stage is referred to as an interca- 

 lated stage because it is inserted between the 

 seemingly regular molt from fifth stage (i.e., Z Vu) 

 to megalopa. 



The measurement for each zoeal stage is the 

 arithmetic mean of all specimens examined. 

 Carapace length was measured from the base of 

 the rostrum to the posterior edge of the carapace 

 along the midline. Carapace width, in the 

 megalopal stage, was measured across the widest 

 part of the carapace. Direction of selation for- 

 mulae in the descriptions progress proximal to 

 distal. 



A complete series of larvae, and or their molts, 

 were deposited in the National Museum of 

 Natural History, Washington, D.C.; the Allan 

 Hancock Foundation, University of Southern 

 California, Los Angeles; the British Museum 

 (Natural History), London; the Rijksmuseum van 

 Natuurlijke Historie, Leiden; the Geneva 

 Museum of Natural History, Geneva; and the 

 Museum National d'Histoire Naturelle, Paris. 



DESCRIPTION OF THE LARVAE 



First Zoeae 



Carapace length: 0.55 mm. 

 Number of specimens examined: 10. 



Carapace (Figure lA, B). Cephalothorax 

 smooth, globose, with dorsal, rostral, and 2 lateral 

 spines. Posteriorly curving dorsal spine usually 

 0.1 ^ longer, but in some specimens equal to or 

 shorter than straight rostral spine. Length of dor- 

 sal spine about 2.75 >i that of short, ventrally 

 curving lateral spines. A minute seta found pos- 

 terior to and at base of dorsal spine throughout all 

 zoeal stages. A dorsal tubercle present in all stages 

 midway between bases of dorsal and rostral 

 spines. Eyes unstalked. 



Ah(/(mu-ri (Figure lA. B). Five somites and tei- 

 son; second through fifth with 2 small setae on 

 posterodorsal margin (remaining throughout all 

 zoeal stages); second with small pair of lateral 

 spines or knobs curving anteriorly; third with pair 

 curving posteriorly (both pair present in all 

 stages); fifth with pair of large ventrally curved 

 spines at dorsolateral angle, present in all zoeal 

 stages. 



360 



