Ucides cordatus cordatus (Linnaeus, 1763) (Crustacea, Decapoda): complete larval development under laboratory conditions and its systematic position

Abstract

Misael Domingues Rodrigues 2Nilton José Hebling 3Six zoeal stages and the megalopa of the comestible crab Ucides cordatus cordatus (Linnaeus, 1763) are described and illustrated. The larvae were reared in the laboratory at temperature 25 ± lOC and water salinity of 24 0 /00; duration of stages and survival rates were measured. Comparisons with the descriptions of the zoeal morphologic characters of Ocypodidae and Gecarcinidae perrnited to include definitively U. c. cordatus in the family Ocypodidae, subfarni1y Ocypodinae. INTRODUCTIONThe comestible crab, Ucides cordatus cordatus, is very commom in the mangrove forests of the Western Atlan tic coast, occurring, according to COELHO & RAMOS (1972), from Florida, Antiles, northern South America, Guiana to Brazil (to the State of Santa Catarina).8ased upon the morphology of the adults, the genus Ucides Rathbun, 1897 has characteristics of both families Gecarcinidae and Ocypodidae. H. MILNE EDWARDS (1837), LEBOUR (1928), RATHBUN (1918RATHBUN ( , 1933, HOLTHUIS (1959), BRIGHT (1966) and PRAHL & MANJARRÉS (1984) considered it in the family Gecarcinidae while CHACE & HOBBS (1969) , TURKA Y (1970, WARNER (1977) and MELO (1985) in the farnily Ocypodidae.ln this paper aredescribed and illustrated alI the larval forms of U. c cordatus.The larval characters are compared with those of the other species of Gecárcinidae and Ocypodidae in order to help solve the controversal systematic position of this genus. MATERIAL AND METHODSOvigerous Jemales of U. c. cordatus were collected on January 18, 1981Research supported by CAPES -PICO. Revta bras. Zoo!.in the mangroves in the canal of Bertioga (23°51 'S, 46°09W), northern litoral of São Paulo, Brazil. After eclosion 60 zoeae were isolated in Petri dishes of 20 mi, with sea water having a salinity of 24 0 /00 and maintained in a climatic room at 25 ± 1 ° C with a photoperiod of 12 hours light and dark. During ali their development, the larvae were fed with freshly hatched nauplii of Artemia salina, after daily changes of water.Dead larvae were fixed and preserved in a mixture of ethol a1cohol 70% and glycerine in a proportion of 1: 1. The exuviae were preserved in glycerine.Measurements and designs were made using a Zeiss microscope with drawing tube. When possible 10 larvae of each stage were analyzed.The following symbols were adopted for the diferent larval stages : I, first zoeal stage; II, second zoeal stage; III, third zoeal stage; IV, fourth zoeal stage; V, fifth zoeal stage that produces zoea VI; V I, fifth zoeal stage that produces directly the megalopa; VI, sixth zoeal stage; MI , megalopa produced by zoea V I ; M2 , megalopa produced by zoea VI.The figures and morphological descriptions of the fifth zoeal stage and of the megalopa were based, respectively, upon stages V and M 2 , because they were most common in the larval development. For stages V I and MI only the alterna te morphologies were mentioned in relation to V and M2 •

Comparative morphology of the first zoea of twelve brachyuran species (Crustacea: Decapoda) from the Amazon region

“…The description of U. cordatus by RODRIGUES & HEBLING (1989) does not differ much from that in the present study. The former did not report the presence of a single seta on the antennule and a small lateral spine on each furca, which also have serrated margins (Table VI).…”

Salinity tolerance of northern Brazilian mangrove crab larvae, Ucides cordatus (Ocypodidae): Necessity for larval export?

“…Adult and juveniles survive long exposures to freshwater (> 3 weeks, Diele, unpublished), but the salinity tolerance of the larvae is not well known. In south-western Brazil Rodriguez and Hebling (1989) cultivated larvae in water with a constant salinity of 24. Survival from hatching to megalopa was 75% and the development comprised 5 to 6 zoeal stages.…”

Duration of the pre-settlement period of the mangrove crab Ucides cordatus (Decapoda: Ocypodidae) under laboratory conditions

“…These periods were considerably longer than the duration of the megalopa stage in the present study, which averaged 12.6 days. The main methodological difference between the present study and that of Rodrigues and Hebling (1989) was the presence of the mangrove sediment within the experimental container. The physicochemical characteristics of the substrates might strongly modulate the decapod metamorphosis, such as temperature (Jamieson and Phillips, 1993;McMillan et al, 1995;Anger et al, 2004), salinity (Islam et al, 2005), and conspecific chemical cues (Harvey, 1996;O'Connor and Judge, 1997;Gebauer et al, 1998;Rodríguez and Epifanio, 2000;Gebauer et al, 2002).…”

“…Thus, the present results suggested that the release of the megalopae on the sixth day from their molt might increase the survivorship of these larvae under natural conditions. The duration of the megalopal stage in U. cordatus has been reported by Rodrigues and Hebling (1989) to last from 55 to 61 days if the megalopae originated from Zoeae V, and from 43 to 69 days, if originated from Zoeae VI. These periods were considerably longer than the duration of the megalopa stage in the present study, which averaged 12.6 days.…”