Taxonomy and molecular phylogenetic position of new species and new records of Coelosphaeridae (Demospongiae: Poecilosclerida) from the Mexican Pacific.

This article focuses on the taxonomy, distribution, and molecular phylogenetics of the family Coelosphaeridae (order Poecilosclerida, class Demospongiae) in the Mexican Pacific Ocean. It describes two new species—*Celtodoryx chichiltik* sp. nov. and *Lissodendoryx (Anomodoryx) incrustans* sp. nov.—and provides new regional records and redescriptions of *Lissodendoryx (Waldoschmittia) hawaiiana* and *Lissodendoryx (Lissodendoryx) albemarlensis*. Molecular analyses using mitochondrial cytochrome c oxidase subunit I (COI mtDNA) and nuclear 28S rDNA sequences reveal that Coelosphaeridae, as well as the genera *Lissodendoryx* and *Celtodoryx*, are not monophyletic, indicating complex phylogenetic relationships within Poecilosclerida. The study also confirms a wide Pacific distribution for *L. (W.) hawaiiana* based on genetic similarity between Mexican and Hawaiian specimens. These findings highlight the need for integrative taxonomy combining morphological and molecular data to resolve systematic challenges in this diverse but understudied sponge group.