Re-establishment of the Family Eumedonidae Dana, 1853 (Crustacea: Brachyura)

On the basis of a re-examination of all available data concerning the systematic position and status of the genus Eumedonus and allied genera it is concluded that these taxa form a separate family within the superfamily Xanthoidea (sensu Guinot, 1978). The family is characterized not only by particular morphological features but by the symbiotic mode of life of its members.     

Larval development of Maja crispata Risso 1827 (Crustacea,Decapoda, Majidae) reared in the laboratory

The morphology of the zoea and megalop of Maja crispata are described from laboratory-reared material, and compared with other two spider crabs belonging to the subfamily Majinae, Maja squinado and Maja goltziana, recorded in the same region of the eastern Atlantic. The diagnostic characters allowing the separation of these species' larvae are tabulated and discussed.     

Comparative population biology of Uca rapax (Smith, 1870) (Brachyura,Ocypodidae) from two subtropical mangrove habitats on the Brazilian coast

The structure of two populations of the fiddler crab Uca rapax in two subtropical mangrove habitats near Ubatuba, State of São Paulo, Brazil were compared. The size–frequency distribution, sex ratio, and recruitment were evaluated. Sampling was performed monthly from April 2001 to March 2002 in the Itamambuca and Ubatumirim habitats. Crabs were caught manually for 15?min by two collectors during low tide. The carapace width of each crab was measured with a digital caliper, and the sex and ovigerous state were recorded. The median size of the carapace width of males was greater than that of females at both sites (P<0.05). The median size of the crabs from Itamambuca was larger than at Ubatumirim (P<0.05). Only 28 ovigerous females were obtained from both mangroves, which suggested that females might remain in their burrows during the incubation period. The highest recruitment pulse occurred in winter for both populations, probably as a consequence of high reproductive activity during summer. The sex ratio in the size classes showed an anomalous pattern, with a higher frequency of females in the intermediate size classes. This may be related to a greater energy requirement for reproduction in females, thus delaying growth. The variable environmental conditions to which Uca rapax populations are subject appear to act directly or indirectly on the population, causing variations in growth and reproductive processes in the different populations investigated here.     

Zoeal development of Ethusa microphthalma smith, 1881 (Brachyura,Dorippidae) reared in the laboratory,with a comparison of other dorippid zoeae

The complete zoeal development of a dorippid crab in the subfamily Ethusinae is described for the first time from a known parental female. The ovigerous Ethusa microphthalma was collected in the northern Gulf of Mexico off Louisiana. Larvae passed through four zoeal stages, and the megalopa was reached in 59 days at 20°C and 35 ppt salinity. The larvae differ from those of the few other dorippids for which a zoea is known. Salient distinguishing features include long lateral carapace spines, the presence of six setae on the endopod of the maxillule and maxilla, and a spinose antennal exopod lacking projecting mid-length spines or setae. Zoeal characters are compared to those known for the allied subfamily Dorippinae, and all references to zoeae of the Dorippidae are tabulated.     

Taxonomy and ecology of the porcellanid crab Polyonyx cometes Walker, 1887 (Crustacea: Decapoda), with description of a new genus

The taxonomy of the rare porcellanid crab, Polyonyx cometes Walker, 1887 (Crustacea Decapoda), is reconsidered in the light of fresh material from Singapore, as well as the newly obtained first zoeal stage. Polyonyx cometes possesses numerous adult and larval characters which warrant the establishment of a new genus for the species. The species is confirmed as a commensal of the worm Chaetopterus (Annelida, Polychaeta).     

Establishment of a new subfamily for Shenius anomalus (Shen, 1935) (Crustacea: Decapoda: Brachyura: Dotillidae)

Shenius anomalus (Shen, 1935 Shen, CJ. 1935. On some new and rare crabs of the families Pinnotheridae, Grapsidae and Ocypodidae from China. Chin J Zool., 1: 19–40. 15 figures [Google Scholar]) has previously been assigned to the Macrophthalmidae Dana, 1851, and the Camptandriidae Stimpson, 1858 Serène, R. 1974. Note on the genera and species of the Camptandriinae Stimpson, 1858 (Decapoda, Brachyura: Ocypodidae). Treubia, 28(3): 59–117.  [Google Scholar]. A close examination of adult and first stage zoeal morphology confirms some previous suggestions that S. anomalus is actually an anomalous member of the Dotillidae Stimpson, 1858 Serène, R. 1974. Note on the genera and species of the Camptandriinae Stimpson, 1858 (Decapoda, Brachyura: Ocypodidae). Treubia, 28(3): 59–117.  [Google Scholar]. However, because a number of distinctive features distinguish it from all other dotillid genera a new subfamily Sheniinae is established.     

The occurrence,mechanics and significance of burying behaviour in crabs (Crustacea: Brachyura)

Although the terms burrowing and burying are often used interchangeably in the literature, there are clear distinctions between these two types of behaviour in terms of their ecological, mechanical and physiological implications. Both types of behaviour are widely observed in the Brachyura. In comparison to the well researched area of burrowing in crabs, information on burying is relatively dispersed. This review will examine the extent of burying behaviour in brachyurans, and the physiological and ecological consequences of the behaviour within the group. At least nine of the 50 families of brachyuran crabs have either been observed to bury in soft substrata or are suspected, on morphological grounds, of burying. There appears to be no specific morphological adaptations for burying in brachyurans, apart from those features associated with respiration whilst buried in the sediment. Buried individuals must ensure constant access to oxygenated water in the face of mechanical problems resulting from direct contact with the sediment, i.e., the threat of clogging. Burying taxa deal with this challenge through accessory respiratory channels and altered respiratory rhythms. The evolutionary implication of the burying habit is equivocal. Burying taxa are amongst the most speciose and numerically dominant brachyuran groups in marine systems, all reaching their greatest diversity and abundance in soft substrata. Burying may be an ancestral condition, with many of these groups evolving in habitats characterized by soft sediment.     

Rhizocephalans (Crustacea: Cirripedia) from Taiwan

One species of shrimp and sixteen species of brachyuran crabs are parasitized by rhizocephalans in Taiwanese waters. Ten of the crabs have never before been recorded as hosts of rhizocephalans. Eight species of rhizocephalans occur in Taiwan. Four species, Diplothylacus taiwanensis, D. calappae, Sacculina scutigera and S. docleae are new to science. The paper records the first example of simultaneous infection of the same host individual by two rhizocephalan species, and provides further evidence of successive moulting of the external mantle cuticle in several species of sacculinids.     

Partial revision of the genus Fabia Dana, 1851 (Crustacea: Brachyura: Pinnotheridae)

Eight species are now assigned to Fabia Dana, 1851. The present partial revision accepts five, F. byssomiae (Say, 1818), F. concharum (Rathbun, 1893), F. emiliai (de Melo, 1971), F. subquadrata Dana, 1851 (type species) and F. tellinae Cobb, 1973, and recommends a future study to determine whether the Brazilian species F. emiliai, is a junior synonym of F. byssomiae. In addition, a new species, F. carvachoi, from the Gulf of California, México is described. The six species are diagnosed and/or described and figured.