Meeting Abstract
P2.102 Tuesday, Jan. 5 Molecular phylogenetic analysis of the sponge genus Mycale (Demospongiae; Poecilosclerida) LOH, T.-L.*; LOPEZ-LEGENTIL, S.; SONG, B.K.; PAWLIK, J.R.; Univ. of North Carolina Wilmington; Univ. of North Carolina Wilmington; Univ. of North Carolina Wilmington; Univ. of North Carolina Wilmington tl7275@uncw.edu
Sponge systematics is largely based on morphological characteristics, specifically the skeletal elements such as spicule and spongin architecture. This presents a challenge as sponges are very plastic morphologically, and change in response to environmental or biotic influences. Molecular studies of sponge taxa have revealed that certain groups were not properly classified and needed to be revised. This study is the first phylogenetic analysis of the genus Mycale using genetic data. Mycale is defined by the presence of these spicules- the palmate anisochela microsclere, which occurs together with a single type of megasclere, usually subtylostyles. As the genus contains approximately 200 species, it is further divided into 11 sub-genera. Fragments of the 18S and 28S rRNA genes were amplified for 12 Mycale species from various sub-genera, with a specific primer designed for the 18S fragment. The 18S and 28S fragments followed the same evolutive model and were combined to increase the total number of variable sites. Phylogenetic analyses were carried out using neighbor-joining, maximum parsimony, maximum likelihood and Bayesian methods with 4 other poecilosclerid sequences and one haplosclerid sequence as the outgroup. Results showed that Mycale is a monophyletic group within Poecilosclerida, but the existence of some sub-genera was not supported. Additionally, the white morph of M. laevis did not group with the other morphotypes of this species and could correspond to a cryptic species. The presence of palmate anisochelae in the Mycale genus is a valid taxonomic character to identify this taxon, but the skeletal architectural characters show homoplasy across different clades within the genus, and should not be used to determine Mycale sub-genera.
