RECORD OF THE PEA-CRAB Calyptraeotheres garthi (FENUCCI, 1975) (BRACHYURA, PINNOTHERIDAE) IN TROPICAL ATLANTIC OCEAN

This study reports the occurrence of the pea-crab Calyptraeotheres garthi (Fenucci, 1975) for the State of Ceará, Northeastern Brazil. The crab was found associated to the calyptraeid limpet Crepidula plana (Say, 1822) in a Voluta ebraea (Linnaeus, 1758) shell occupied by the hermit crab Petrochirus diogenes (Linnaeus, 1758). This record represents the northernmost occurrence for the species in the Atlantic Ocean and the second for Brazilian waters. This new record increases the distribution area of C. garthi in about 3520 km. Taxonomic and biogeographic remarks, ecological notes and an updated distribution map are provided for this species.

Calyptraeotheres garthi (Fenucci, 1975) is distributed in Brazil (state of Rio Grande do Sul) and Argentina and can be found in the mantle of calyptraeid gastropods of the genera Crepidula Lamarck, 1799, Bostrycapulus Olsson and Harbison, 1953, and Trochita Schumacher, 1817, usually associated to shells used by the hermit crab genera Petrochirus Stimpson, 1858, and Dardanus Paulson, 1875(Hernández-Ávila & Campos, 2006Ayón-Parente & Hendrickx, 2016;Boschi, 2016). Taking into consideration that the pinnotherid group is still poorly known in Brazil, especially in the states of northeast (Bezerra et al., 2006), the aim of this contribution is to provide the northernmost record of C. garthi in Atlantic Ocean, particularly in warm waters from the Northeastern Brazil.
Sampling was carried out on November 2010 at the Pacheco beach, municipality of Caucaia, state of Ceará, Brazil (3°41'11.66" S 38°37'58.78" W). This area is an open beach characterized by predominance of ferruginous sandstone reefs with predominance of macro algae and a rich marine invertebrate fauna, including mainly crustaceans and mollusks (Matthews-Cascon et al., 2005). One shell of Voluta ebraea Linnaeus, 1758, occupied by the hermit crab Petrochirus diogenes (Linnaeus, 1758) was obtained by a fisherman with a otter trawl in the subtidal zone. The specimen was brought to the laboratory and examined. A specimen of the limpet Crepidula plana Say, 1822 ( Figure 1A, B, C) was removed from the V. ebraea shell and two pea-crabs were found below Crepidula's shell ( Figure 1B). The host and your symbiont crabs were photographed and posteriorly cryo-anesthetized and fixed in 70% ethanol.

REMARKS
The genus Calyptraeotheres was erected to include the species Fabia granti Grassel, 1933, based on the carapace with sharp-edged anterolateral margins and the third maxilliped palp with two articles, carpus longer than propodus and pleon of seven free somites . Calyptraeotheres garthi (as Pinnotheres garthi Fenucci, 1975) was registered in Brazil for the first time by Martins & D'Incao (1996) in the municipality of Rio Grande, state of Rio Grande do Sul.

Felipe Bezerra Ribeiro, Helena Matthews-Cascon, Luís Ernesto Arruda Bezerra
However, the studies on this family are still very scarce from Brazil. This record represents the northernmost occurrence for the species in the Atlantic Ocean, being the first record of C. garthi from Northeastern Brazil and the second for Brazilian waters. This new record increases the distribution area in about 3520 km.
The initial distribution indicated that the species was restricted to cold waters, being a species of the Argentinian Province following the biogeographic classification of Boschi (2000), where the surface temperature ranges from 8° to 23 °C in the south sector (Bueno Aires) and from 12.5° to 25 °C in the northern sector in southern Brazil (Hereu, 1999). However, the present record in tropical waters extends the distribution of the species and includes it as a species occupying also the Brazilian Province, where temperatures vary from 22 °C in the south to 30 °C in the north limits of the Province. According to Boschi (2000), the Argentinian Province can be characterized as a warm temperate province with 330 species, 42 of which are endemic while the in the Brazilian Province the estimated number of decapod crustacean species is 572, 64 of which are endemic.
The present record of C. garthi in the Brazilian province extends its distribution to both provinces, as other species of Brachyura such as Apiomithrax violaceus (A. Milne-Edwards, 1868), Arenaeus cribrarius (Lamarck, 1818), among others. The host species Crepidula plana also occurs in both provinces (Rios, 2002).