A new species of the calcareous sponge genus Leuclathrina (subclass Calcinea) from the Maldives. A new species of the calcareous sponge genus Leuclathrina (subclass Calcinea) from the Maldives

The diversity and phylogenetic relationships of calcareous sponges are still incompletely understood. Recent integrative approaches, which combined analyses of DNA and morphological data, resulted in severe taxonomic revisions, especially in the subclass Calcinea, which lay the foundation for a phylogenetically meaningful classification. However, several genera are missing from DNA phylogenies, and their relationship to other Calcinea remain uncertain. One of these genera is Leculathrina Borojevic & Boury-Esnault (family Leucaltidae, Dendy and Row). We here describe a new species from the Maldives, Leuclathrina translucida sp. n., which is only the second species of the genus. Like the type species, it possesses the typical leuconoid aquiferous system and lacks a specialized choanoskeleton. Phylogenetic analyses of the partial 28S ribosomal RNA gene revealed that L. transclucida n. sp. is most closely related to a clade containing the exclusively asconoid genera Ascandra, Levinella and Soleneisus, as well as to a clade of the likewise asconoid genus Ernstia. No close relationship existed to any members of the polyphyletic family Leucaltidae, or to any other leuconoid Calcinea. Our results suggest that the leuconoid aquiferous system of Leuclathrina evolved independently from that of other calcineans and that the family assignment of the genus has to be reconsidered. Because the latter requires a more comprehensive family level revision among many genera of Calcinea, we propose to formally keep the genus in Leucaltidae until then.