A new species of the family Callianassidae (Crustacea: Decapoda: Axiidea) from vent fields at Tofua Arc in the Southwest Pacific

Abstract

A population of ghost shrimp was isolated from sediments of vent fields collected by TV grab of R/V SONNE. Calliaxina sp. nov. was identified a new species of the family Callianassidae. The new species is described and illustrated on the basis of 18 specimens. The habitat of this species was determined by zinc (Zn) poor crust in low temp vent fields. Calliaxina sp. nov. is characterized by broadly triangular rostrum, pointed lateral projections on carapace, laterally compressed chelipeds (first pair of legs) and third maxillipeds with the presence of exopods as found the other nominal species belonging to the genus Calliaxina Ngoc-Ho, 2003. However, it mainly differs by asymmetrical-sized chelipeds and absent denticules on the lower marginal side of ischium and merus in shape from congeners. In addition, three mitochondrial 16S ribosomal DNA (16S rDNA) sequences were newly determined from Calliaxina sp. nov. This new species show the closest relationship with C. sakaii (Accession No. EU882905, bootstrap value 83 % in NJ) based on 16S rDNA. This study combined morphological and molecular approach helps delineate the phylogenetic relationship within the family Callianassidae that is a complex group in decapods.e basis of 18 specimens. The habitat of this species was determined by zinc (Zn) poor crust in low temp vent fields. Calliaxina sp. nov. is characterized by broadly triangular rostrum, pointed lateral projections on carapace, laterally compressed chelipeds (first pair of legs) and third maxillipeds with the presence of exopods as found the other nominal species belonging to the genus Calliaxina Ngoc-Ho, 2003. However, it mainly differs by asymmetrical-sized chelipeds and absent denticules on the lower marginal side of ischium and merus in shape from congeners. In addition, three mitochondrial 16S ribosomal DNA (16S rDNA) sequences were newly determined from Calliaxina sp. nov. This new species show the closest relationship