Host species, range extensions, and an observation of the mating system of Atlantic shallow-water gall crabs (Decapoda: Cryptochiridae)

Coral-associated invertebrates dominate the biodiversity of coral reefs. Some of the associations involving symbiotic invertebrates remain unknown or little studied. This holds true even for relatively wellstudied coral reefs, like those in the Caribbean Sea. Coral gall crabs (Cryptochiridae), obligate symbionts of stony corals, form a much-overlooked component of coral reef communities. Most recent studies on the Atlantic members of Cryptochiridae have been conducted off Brazil and little recent data have become available from the Caribbean region. During fieldwork off Curaçao (southern Caribbean Sea), eight new host coral species, belonging to four coral families, were recorded for three cryptochirid species. Kroppcarcinus siderastreicola Badaro, Neves, Castro and Johnsson, 2012, previously only known from Brazil, and Opecarcinus hypostegus (Shaw and Hopkins, 1977) are new additions to the fauna of Curaçao. Besides the new hosts and geographic range extensions, a free-living male Troglocarcinus corallicola Verrill, 1908 was observed visiting a female of the same species lodged in her gall in an Orbicella annularis (Ellis and Solander, 1786) colony. This is the first photodocumented record of the "visiting" mating system in Cryptochiridae

Host preferences, colour patterns and distribution records of pseudocryptochirus viridis hiro, 1938 (Decapoda, Cryptochiridae)

The coral gall crab Pseudocryptochirus viridis is an obligate symbiont of some species of the Indo-West Pacific coral genus Turbinaria. The colour pattern variation within the species is illustrated for the first time. Overviews of the coral host species and distribution records are provided, including new records from Indonesia, Malaysia and Australia

Host species, range extensions, and an observation of the mating system of Atlantic shallow-water gall crabs (Decapoda: Cryptochiridae)

Coral-associated invertebrates dominate the biodiversity of coral reefs. Some of the associations involving symbiotic invertebrates remain unknown or little studied. This holds true even for relatively wellstudied coral reefs, like those in the Caribbean Sea. Coral gall crabs (Cryptochiridae), obligate symbionts of stony corals, form a much-overlooked component of coral reef communities. Most recent studies on the Atlantic members of Cryptochiridae have been conducted off Brazil and little recent data have become available from the Caribbean region. During fieldwork off Curaçao (southern Caribbean Sea), eight new host coral species, belonging to four coral families, were recorded for three cryptochirid species. Kroppcarcinus siderastreicola Badaro, Neves, Castro and Johnsson, 2012, previously only known from Brazil, and Opecarcinus hypostegus (Shaw and Hopkins, 1977) are new additions to the fauna of Curaçao. Besides the new hosts and geographic range extensions, a free-living male Troglocarcinus corallicola Verrill, 1908 was observed visiting a female of the same species lodged in her gall in an Orbicella annularis (Ellis and Solander, 1786) colony. This is the first photodocumented record of the "visiting" mating system in Cryptochiridae

Host relations and DNA reveal a cryptic gall crab species (Crustacea: Decapoda: Cryptochiridae) associated with mushroom corals (Scleractinia: Fungiidae)

Mushroom corals of the Indo-West Pacific Fungiidae (Scleractinia) provide habitats for a rich associated fauna, including three species of gall crabs (Cryptochiridae). During the course of the present study gall crabs were sampled from many different fungiid hosts. Based on this ‘reversed’ approach - by studying coral symbionts from a host perspective - a previously unnoticed host specificity pattern was detected. The sampling of gall crab fauna per host coral combined with molecular analyses of H3 nDNA, 16S and COI mtDNA revealed a cr yptic gall crab species closely related to Fungicola fagei. This new species, described hereafter as Fungicola syzygia sp. nov., is predominantly associated with the mushroom coral genera Cycloseris and Pleuractis, whereas its sibling species F.fagei is only known to be associated with the host genera Podabacia and Sandalolitha. Based on morphology F.syzygia sp. nov. is difficult to distinguish from F.fagei, but there are subtle differences in carapace shape, the lateral carapace margins, the border between the orbital angles and the merus of the third maxilliped, as well as in the carapace length/width ratio. The type material of F.utinomi and F.fagei is figured for comparison

Host preferences, colour patterns and distribution records of pseudocryptochirus viridis hiro, 1938 (Decapoda, Cryptochiridae)

The coral gall crab Pseudocryptochirus viridis is an obligate symbiont of some species of the Indo-West Pacific coral genus Turbinaria. The colour pattern variation within the species is illustrated for the first time. Overviews of the coral host species and distribution records are provided, including new records from Indonesia, Malaysia and Australia

Monophyly and phylogenetic origin of the gall crab family Cryptochiridae (Decapoda: Brachyura)

The enigmatic gall crab family Cryptochiridae has been proposed to be phylogenetically derived from within the Grapsidae (subsection Thoracotremata), based on the analysis of 16S mtDNA of one cryptochirid, Hapalocarcinus marsupialis, among a wide array of thoracotremes, including 12 species of the family Grapsidae. Here, we test the monophyly and phylogenetic position of Cryptochiridae using the same gene, but with an extended representation of cryptochirids spanning nine species in eight of 21 genera, in addition to further thoracotreme representatives. The results show that gall crabs form a highly supported monophyletic clade within the Thoracotremata, which evolved independently of grapsid crabs. Therefore, the Cryptochiridae should not be considered as highly modified Grapsidae, but as an independent lineage of Thoracotremata, deserving its current family rank. Further molecular and morphological studies are needed to elucidate the precise placement of the cryptochirids within the Eubrachyura

Distribution of gall crabs inhabiting mushroom corals on Semporna reefs, Malaysia

Coral reef cryptofauna forms an important component of tropical marine biodiversity, consisting primarily of invertebrates dwelling in and on corals. During a survey carried out around the Semporna peninsula (Sabah, NE Borneo), the occurrence of gall crabs inhabiting mushroom corals was examined on reefs ranging from sheltered to exposed conditions. Out of 44 fungiid species, 19 were found to be associated with gall crabs. The gall crabs were observed at 85 % of the 62 studied sites, and their occurrence rates per site ranged between 0 and 25 %. High occupancy rates were almost equally distributed over the northern (sheltered) and southern (exposed) sites. Sites without gall crabs were all wave-exposed and predominantly under the influence of disturbances, such as blast fishing or relatively high nutrient loads. © 2012 Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg