Middle East Caridina (Decapoda: Atyidae): Redescription of C. fossarum Heller, 1862, description of three new species, and remarks on the status of C. syriaca Bouvier, 1904 and C. babaulti basrensis Al-Adhub & Hamzah, 1987

Abstract

The most species-rich genus, Caridina, of the shrimp family Atyidae is broadly distributed throughout five biogeographic realms, with the Indo-Malayan realm being the centre of its distributional range. Due to the scarcity of studies, very little is known regarding the Middle East species, which are placed on the north-western edge of the genus’ distribution. Numerous museum specimens from across the entire range of Caridina in the Middle East were thus analysed using morphological characters and mitochondrial sequences (16S) in order to gain insight into the biodiversity of the genus in the region. Consequently, the present study describes three new atyid species of the genus Caridina H. Milne Edwards, 1837, Caridina enbilului sp. nov., Caridina enkii sp. nov. and Caridina shahrazadae sp. nov. from freshwater habitats of Syria, Iraq and Iran respectively. Furthermore, Caridina fossarum Heller, 1862 is redescribed, while the taxonomic status of Caridina syriaca Bouvier, 1904 and Caridina babaulti basrensis Al-Adhub & Hamzah, 1987 is discussed and the latter synonymized with Caridina fernandoi Arudpragasam & Costa, 1962. C. shahrazadae sp. nov. differs from its congener C. fossarum by the reduced branchial formula of the latter species, the absence of an appendix interna at the endopod of the male's first pleopod, and the lack of a prominent sexual dimorphism on the propodus of the third and fourth pereiopods. C. enbilului sp. nov. differs from C. fossarum in the same characters as C. shahrazadae sp. nov., while from the latter species C. enbilului sp. nov. is different in showing a distinct tooth on the pterygostomial margin of the carapace, by a well-developed arthrobranch on the first pereiopod, a well-developed podobranch on the second maxilliped and a more slender endopod of the male's first pleopod. C. enkii sp. nov. can be distinguished from C. fossarum by the more developed sexual appendages of male specimens as well as more slender pereiopods. In addition, the genetic analysis supports the existence of multiple species in the Middle East, while their phylogenetic relationships and their geographic distribution are described.