A comparative study of the larval development of Monodaeus couchi (Couch), Xantho incisus Leach and Pilumnus hirtellus (Linnaeus) (Crustacea: Brachyura: Xanthidae)

Summary

Comparative accounts are given of the larval and first crab stages of three crab species belonging to the family Xanthidae: Monodaeus couchi (Couch), Xantho incisus Leach and Pilumnus hirtellus (Linnaeus). Features are discussed that distinguish the larvae of these species from those of other N.E. Atlantic brachyrhynch crabs.     

Iphitime cuenoti Fauvel (Eunicidae), a polychaete new to British waters

Summary

The polychaete Iphitime cuenoti was found inhabiting the branchial chamber of the spider crab Macropodia longirostris in the Isle of Man area. The species of Iphitime and previous records of their occurrence are summarised. The sexual dimorphism of the polychaete is discussed, and its mode of nutrition and relations with its host considered. Ophryotrocha geryonicola, another polychaete inhabiting the branchial chamber of decapods, is compared with Iphitime.     

Aspects of the natural history of the swordtail jawfish,Lonchopisthus micrognathus (Poey) (Pisces: Opistognathidae), in south-western Puerto Rico

Summary

The burrow-dwelling jawfish, Lonchopisthus micrognathus, occurs at 12–40 m depths on sandy-mud substrates in back reef areas off southwestern Puerto Rico. Its behaviour is remarkably similar to Opistognathus aurifrons. It feeds on suspended material in the water. The burrow has a primary opening with a vertical tube and smaller accessory openings. A crab, Chasmocarcinus cylindricus, occurs with it. Lonchopisthus micrognathus broods its eggs orally and may spawn the year round. Availability of suitable sediment is not limiting distribution of the species.     

Laboratory rearing of the larval stages of Carcinus maenas (L.) [Crustacea: Decapoda]

Summary

Larvae of Carcinus have been reared to the crab stage for the first time in the laboratory. Artemia nauplii were successful as food from Stage II zoeae onwards and Stage I zoeae fed and moulted successfully on the dinoflagellate Prorocentrum. Animal foods smaller than Artemia were not tried, but the larvae or eggs of molluscs, echinoderms or polychaetes would probably be suitable. Entirely algal diets were unsatisfactory for complete development.

On diets of Prorocentrum and Artemia, the overall survival rates to first crab stage were about 30% and the average total development time was 57·7 days. Average duration of each larval stage, in days, was 14·8 (zoea I), 7·9 (zoea II), 9·6 (zoea III), 10·0 (zoea IV) and 15·4 (megalopa).     

Ectosymbionts of the non‐indigenous Asian shore crab,Hemigrapsus sanguineus (Decapoda: Varunidae), in the western north Atlantic,and a search for its parasites

Over 560 Asian shore crabs, Hemigrapsus sanguineus, collected mainly in the spring of 2005 and 2006 from rocky intertidal locations in southern New Jersey, were examined for epibionts. Small numbers of the sympatric green crab, Carcinus maenas, and the Atlantic mud crab, Panopeus herbstii, were examined for epifauna to compare with H. sanguineus. Blue mussel spat, Mytilus edulis, and the encrusting, cheilostome bryozoan, Conopeum tenuissimum, were the dominant ectosymbionts of the shore crab, with prevalences of 22.2 and 32.1%, respectively; ranges of intensity were 1–146 spat/crab and 1–31 colonies/crab. Both species are incidental symbionts. Larger crabs had higher prevalences and intensities of C. tenuissimum colonies, and these colonies displayed a distinct pattern of attachment to the carapace which seemed to be related to crab morphology and habitat. Much less common was the encrusting, ctenostome bryozoan Alcyonidium albescens, a facultative symbiont species with a prevalence of 3.4%. Other epibionts were the encrusting, cheilostome Membranipora tenuis, the tubicolous polychaetes Hydroides dianthus, Sabellaria vulgaris, and Spirorbis sp., the barnacles Balanus improvisus and Semibalanus balanoides, and unidentified thecate hydroids, all incidental symbionts with prevalences from 0.2 to 3.2%. The total number of known ectosymbionts of H. sanguineus, including additional species found previously in the USA and the western Pacific, is 13. Carcinus maenas and P. herbstii share some of the same symbionts. Rhizocephalan externae were not observed in any of the crab species used in this study, nor were gill parasites or internal parasites found among 248 specimens of H. sanguineus.     

A description of Ucides occidentalis Ortmann, 1897 (Crustacea : Decapoda : Ocypodidae) zoea I.

ABSTRACT

In order to facilitate the ecological study of the economically important red mangrove crab Ucides occidentalis, we describe the zoea I phase using samples hatched from gravid females taken from the Guayas River Estuary of Ecuador. No other phases of this species’ larval development have been described. The morphological differences between this developmental phase in U. occidentalis and its single congener U. cordatus that may be diagnostic include the number of segments in the pleon, the setation pattern of the basial endopodite of the maxillule, and, in maxillipeds I and II, the segmentation of the terminal plumose natatory setae.     

Larval development and emigration behaviour during sea-to-land transition of the land hermit crab Coenobita brevimanus Dana, 1852 (Crustacea: Decapoda: Anomura: Coenobitidae) under laboratory conditions

To determine the early life history of the land hermit crab Coenobita brevimanus Dana, 1852, larvae were cultured individually in the laboratory. The zoeal and the megalopal stages are described and illustrated. The larvae developed through four planktonic zoeal stages to the megalopal stage. The major differences in the zoeal characters between C. brevimanus and other described Coenobita species were found in the armature of the pleomeres, whereas the character of pleomeres of C. brevimanus zoeae is the same as that of the coconut crab Birgus latro, a different genus in the same family. Morphological similarity was also found in segmentations of antennules and antennae in megalopae between C. brevimanus and the coconut crab. Megalopae of C. brevimanus were cultured in containers holding seawater and a hard substrate. These crabs migrate from the sea to land after developing a habit of acquiring gastropod shells.     

On some Indian species of Aphelinidae,with a description of a new Coccophagus (Hymenoptera: Chalcidoidea)

Summary

The Philippine cruise of the U.S. Fisheries Steamer Albatross 1907–10 collected 61 species of spider crabs from the Philippine Islands bringing the total number of species known from the area to 71; 28 new species were described by Rathbun and the present report records 19 species not previously known from the area; included are nine widespread Indo-west Pacific forms, four previously known from Japan and four Indian Ocean species.

Hyastenus sebae White is renamed H. whitei and the former name is applied to H. oryx A. Milne Edwards. Hyastenus tuberculosus Rathbun is confirmed as a synonym of H. convexus Miers, Platymaia remifera Rathbun is reduced to synonomy with P. wyvillethomsoni Miers and Chorilia sphenocarcinoides Rathbun is transferred to the genus Sphenocarcinus.

The majority of species (51) occur around the central and southern islands of the archipelago and most of these (35 speciesl occur at varying depths on the continental shelf. Twelve species occur intertidally and 21 species are known from depths over 100 fms, some occurring as deep as 800 fms.

The spider crab fauna is clearly part of the Indo-west Pacific, 25 species being widespread ones; 26 species are shared with Japan, 24 with Australia and 31 with the Indian Ocean. However, 20 species appear to be confined to the Philippine Islands. The relationships of the Philippine fauna with that of the rest of Indonesia is not yet clear     

Notes on Simulium ovazzae Grenier and Mouchet (Diptera: Simuliidae) and river crabs (Malacostraca: Potamidae) and their association

Summary

Collections of crabs in the forest zone of West Cameroon produced three species—Potamonautes africanus, P. orthostylis and P. pobeguini. The P. africanus carried populations of immature Simulium ovazzae.

Analysis of crabs collected by hand and those collected in traps indicates very little overlap in the sizes of the crabs obtained by the two techniques. This problem is discussed.

The infestation rates of S. ovazzae on P. africanus were found to be highest on medium-sized crabs. The attachment sites of the S. ovazzae on the crabs were found to vary with both the size of the crab and the size of the Simulium larva.

The size distributions of S. ovazzae larvae on small crabs were found to be different from those on medium and large crabs. The characteristic deficiency of smaller larvae on medium and large crabs reported for other crab-phoretic species was also found with S. ovazzae but the smaller crabs showed a deficiency of larger larvae. A hypothesis is put forward to explain the dearth of larger larvae on the smaller crabs and the higher infestation rate on medium crabs.

S. ovazzae are shown to arrive on their hosts as single larvae carried by the current.

Six adult S. ovazzae were reared from pupae in the laboratory. Small numbers of presumed S. ovazzae biting man in Cameroon are reported.     

Natural diet of fish and crabs associated with the phytal community of Sargassum cymosum C. Agardh, 1820 (Phaeophyta,Fucales) at Ponta das Garoupas,Bombinhas, Santa Catarina State,Brazil

The diet of fish and crabs associated with Sargassum cymosum beds was analysed at Ponta das Garoupas, Santa Catarina State, southern Brazil. They are reported to feed on phytal organisms. The relative importance of food items was established for these consumers, and the frequency of occurrence and volumetric methods were used for quantitative analysis. The analysis of 272 guts from 11 fish and two decapod species revealed that eight fish and one crab species had phytal organisms as important items in their diet. Amphipods and molluscs were the main phytal animals in the diet of these fish and the crab; notably Caprella scaura, Hyale media, Atylus minikoi, Tricolia affinis and Bittium varium. Commercially important fish, such as the grouper Epinephelus guaza, feed on these fish and crabs, showing that Sargassum beds constitute an important link between benthic autotrophic producers and several levels of consumers on rocky shore ecosystems at Ponta das Garoupas.     

Juvenile development and growth patterns in the mud crab Eurytium limosum (Say, 1818) (Decapoda,Brachyura, Xanthidae) under laboratory conditions

The post‐larval development of the mud crab Eurytium limosum was studied under laboratory conditions by using the offspring of ovigerous females collected at the Comprido River mangrove, SP, Brazil. The first crab stage is fully described and the juvenile development, until crab stage 10, is examined with emphasis on morphological change, sexual differentiation and growth patterns. The carapace of the first crab stage is nearly square as observed in other xanthids, becoming similar to adults only at stage 15. The sexes can be distinguished from stage four, based on the number of pleopods and their morphology. While the intermoult period increases, the moult percentage decreases at each stage. The abdominal allometric growth is sex‐dependent, with males showing a negative (b?=?0.71) and females an isometric (b?=?0.95) relative growth pattern. Male gonopods undergo a positive allometric growth, and their shape changes remarkably until sexual maturity. The cheliped dentition can be observed after stage 4. Regardless of sex, most crabs have a molariform right cheliped, which is thought to aid the handling of asymmetric prey such as gastropods.     

Symbiotic associations between hermit crabs and bryozoans from the Otago region,southeastern New Zealand

Thirteen species of bryozoans (six cyclostomes and seven cheilostomes) occurring off the Otago Peninsula (southeastern New Zealand) form symbiotic, possibly mutualistic, associations with hermit crabs. For all but one of these bryozoan species, such an association has not been reported previously. At most only 3 of the 13 bryozoans are obligate symbionts of hermit crabs. Associations are apparently initiated when a bryozoan larva settles on a gastropod shell occupied by a juvenile hermit crab and develops to form a colony which encrusts the whole shell and then continues to grow out beyond the shell aperture in the form of a helicospiral tube. The tube-building bryozoan colony grows in step with the crab, and tube development appears to be controlled by crab morphology and activity. Of the six species of hermit crabs found occupying bryozoan tubes, four were regular tube occupants, although they could also be found in other shelter types. Hermit crabs occupying bryozoan tubes very rarely indulged in shell exchanges or shell fights. There appear to be no clear cut pairwise correlations between hermit crab species and tube-forming bryozoan species. The following bryozoan species are described for the first time: Heteropora parapelliculata, Borgiola otagoensis, Disporella gordoni, Osthimosia monilifera and O. socialis.     

On a new genus and new species of xanthid crab (Crustacea,Decapoda, Brachyura,Xanthinae) from the South China Sea,with notes on the genus Liagore De Haan, 1833

A new genus and new species of xanthid crab, Ovatis simplex, is described from the South China Sea. The genus is closest to Liagore but can be distinguished by a suite of carapace and male gonopod characters. The systematic position of Liagore is also considered, and both genera, Liagore and Ovatis, are here referred to the subfamily Xanthinae. Comparisons with the allied genera, Paratergatis and Pulcratis, are also provided.     

A new species of Himalayapotamon Pretzmann, 1966 (Crustacea: Brachyura: Potamidae) marking the westernmost distribution of the genus,with notes on its geographical range evolution

ABSTRACT

We describe a new species of freshwater crab, Himalayapotamon robertsianum sp. nov. from Punjab province of Pakistan, based on morphological characters of the carapace and the first gonopod. The new species demarcates the westernmost distribution limit of the genus. Additionally, we analysed partial sequences of the 16S rRNA locus for some species of the genus Himalayapotamon (p-distances, Bayesian phylogenetical inference), indicating that Himalayapotamon separates into an eastern and a western clade. Based on these results, we propose a biogeographical scenario that can explain the occurrence of the genera Himalayapotamon and Potamon within the same river system: we assume an ancestral widespread distribution of Himalayapotamon in the palaeo-Ganges. When drainage rearrangement diverted the western tributaries of the Ganges into the Indus since the latest Miocene, Himalayapotamon diverged into two clades. Consequently, the western clade is now sharing the Indus drainage with Potamon.

urn:lsid:zoobank.org:pub:80B52E6C-0120-4669-A6B0-9F0DA5918EE3     

Studies on the provenzanoi and other pagurid groups: VI. Larval and early juvenile stages of Pagurus ochotensis Brandt (Decapoda; Anomura; Paguridae) from a northeastern Pacific population,reared under laboratory conditions

Zoeal, megalopal, and early juvenile stages of Pagurus ochotensis (Brandt, 1851) from a northeastern Pacific population are described from laboratory-reared individuals. Zoeal and megalopal development in this population is compared with that described for a population of this species from Hokkaido, Japan. First and second juvenile crab stages of this species are described for the first time. The nearly identical developmental morphology of the two populations supports the earlier synonymy of the northeastern Pacific species, Pagurus alaskensis (Benedict) with P. ochotensis.     

Aspects of mangal ecology along the Red Sea coast of Saudi Arabia

Surveys of the mangal along the Red Sea coast of Saudi Arabia form the basis of this study. Both soft-bottomed mangals and the less well known hard-bottomed mangals are represented. The distribution of Avicennia marina, the dominant mangrove species, is discontinuous in the northern part of the Red Sea. Its development increases southwards, and mean height is inversely correlated both with latitude (P<0·05) and salinity (P<0·05). Another species, Rhizophora mucronata, was recorded in only five areas. Molluscs and crabs represent the principal faunal elements within the mangal. The density of Cerithidea cingulata, the dominant mollusc species, shows significant correlation (P<0·01) with the abundance of blue-green algae. Four species of fiddler crab (Uca) are included among the crab fauna of the mangal, one of which (U. urvillei) is here newly recorded for the Red Sea. Evidence is given for suggesting that the mangal biota in the region sampled may not be distinctive. Rather, it consists of many species found not only within the mangal but also in other habitats such as seagrass beds and even rock beaches. It is suggested that the mangal of the Red Sea represents a composite habitat, containing both hard and soft substrates and inhabited by species typical of each. This contrasts with the situation in most other mangals studied.