Discordance between morphological and molecular species boundaries among Caribbean species of the reef sponge Callyspongia

Sponges are among the most species-rich and ecologically important taxa on coral reefs, yet documenting their diversity is difficult due to the simplicity and plasticity of their morphological characters. Genetic attempts to identify species are hampered by the slow rate of mitochondrial sequence evolution characteristic of sponges and some other basal metazoans. Here we determine species boundaries of the Caribbean coral reef sponge genus Callyspongia using a multilocus, model-based approach. Based on sequence data from one mitochondrial (COI), one ribosomal (28S), and two single-copy nuclear protein-coding genes, we found evolutionarily distinct lineages were not concordant with current species designations in Callyspongia. While C. fallax,C. tenerrima, and C. plicifera were reciprocally monophyletic, four taxa with different morphologies (C. armigera,C. longissima,C. eschrichtii, and C. vaginalis) formed a monophyletic group and genetic distances among these taxa overlapped distances within them. A model-based method of species delimitation supported collapsing these four into a single evolutionary lineage. Variation in spicule size among these four taxa was partitioned geographically, not by current species designations, indicating that in Callyspongia, these key taxonomic characters are poor indicators of genetic differentiation. Taken together, our results suggest a complex relationship between morphology and species boundaries in sponges

Diversity of Saint Helena Island and zoogeography of zoantharians in the Atlantic Ocean: jigsaw falling into place

Diversity surveys in isolated sites, such as oceanic islands, provide biogeographic data that can improve our analyses and knowledge of evolutionary processes in the oceans. Zoantharians (Cnidaria: Anthozoa) are common and widespread components of shallow-water reefs, but distributional analyses are scarce for this group. In this study, we collected Zoantharia specimens from around Saint Helena Island (STH) in the mid-Atlantic and identified species using external morphology and molecular data. Moreover, we compiled and analysed the most comprehensive distributional data for zoantharian species in the subtropical and tropical Atlantic Ocean to date. Our results show eight zoantharian species in STH, which includes seven new records for STH waters. Furthermore, all families and genera of the suborder Brachycnemina recorded are widespread in the Atlantic Ocean, including at least four amphi-Atlantic species. The Caribbean is the richness centre in the Atlantic Ocean for zoantharian species, a pattern similar to that observed for many other subtropical/tropical marine taxa. However, Zoantharia may have a lower endemism rate in some areas than other common reef animals, for example zooxanthellate scleractinian corals and reef fishes. Moreover, zoantharian species have a more extensive distribution than close-related taxa such as zooxanthellate scleractinian corals and hydrocorals in the Atlantic Ocean.Japanese Government (MEXT)Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT)JSPSMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Scienc