The present study is a review of the excavating and endolithic sponges present in the Mediterranean. A dichotomic key to 22 species is presented. Detailed species descriptions are provided based on newly collected material and previous descriptions from the literature. In the case of
Cliona viridis (Schmidt, 1862), an in-depth histological study has also been performed. Discussions on problematic taxonomic issues are also included.
Dotona pulchella Carter, 1880 subspecies
mediterranea subsp. n. is described. The previously enacted synonymy between
Pione vastifica Hancock, 1849 and
Pione lampa (de Laubenfels, 1950) is restricted to those specimens identified as “forma
occulta”.
Cliona amplicavata Rützler, 1974 is recorded for the first time in the Mediterranean.
Cliona cretensis Pulitzer-Finali, 1983 is proposed to be synonymous to
Cliona thoosina Topsent, 1887.
Cliona copiosa Sarà, 1959 and
Cliona tremitensis Sarà, 1961 are considered synonymous to
C. viridis. The spicule complement of
Scantilletta levispira (Topsent, 1898),
D. pulchella and
C. amplicavata is enlarged, and some spicule types are better described based on light microscopy and SEM observation.
Pione vastifica shows great variability in the microrhabds, seemingly related to depth. Regarding excavating patterns, several species appear to selectively excavate particular substrate types, whereas others are not selective among calcareous materials.
A. labyrinthica,
P. vastifica,
Cliona janitrix Topsent, 1932,
C. viridis and
C. lobata Hancock, 1849 have asexual reproduction. Excavating ability, bud production and the way the sponge grows inside the substrate are biological features common to distant taxa such as Clionidae and
Aka spp. that may constitute convergent (analogous) characters.
