Taxonomic revision of the agaraceae with a description of Neoagarum gen. nov. and reinstatement of Thalassiophyllum
We confirmed the monophyly of the Agaraceae based on phylogenetic analyses of 6 mitochondrial and 6 chloroplast gene sequences from Agarum, Costaria, Dictyoneurum and Thalassiophyllum species as well as representative species from other laminarialean families. However, the genus Agarum was paraphyletic, comprising two independent clades, A. clathratum/A. turneri and A. fimbriatum/A. oharaense. The latter clade was genetically most closely related to Dictyoneurum spp., and morphologically the species shared a flattened stipe bearing fimbriae (potential secondary haptera) in the mid to upper portion. The phylogenetic position of Thalassiophyllum differed between the two datasets: in the chloroplast gene phylogeny Thalassiophyllum was included in the A. clathratum/A. turneri clade, but in the mitochondrial gene phylogeny, it formed an independent clade at the base of the Agaraceae, the same position it took in the phylogeny when the data from both genomes were combined despite a larger number of bp being contributed by the chloroplast gene sequences. Considering the remarkable morphological differences between Thalassiophyllum and other Agaraceae, and the molecular support, we conclude that Thalassiophyllum should be reinstated as an independent genus. Dictyoneurum reticulatum was morphologically distinguishable from D. californicum due to its midrib, but because of their close genetic relationship, further investigations are needed to clarify species level taxonomy. In summary, we propose the establishment of a new genus Neoagarum to accommodate A. fimbriatum and A. oharanese and the reinstatement of the genus Thalassiophyllum.
Porifera (Sponges) from Japanese Tsunami Marine Debris arriving in the Hawaiian Islands and on the Pacific coast of North America
Twelve species of sponges (Calcarea and Demospongiae) were found on Japanese Tsunami Marine Debris (JTMD) that washed ashore in Oregon, Washington, and Hawai‘i. All taxa but one determined to species level are amphi-Pacific, with three having type localities in California (Leucosolenia eleanor Urban, 1906, Hymeniacidon sinapium de Laubenfels, 1930, and Mycale macginitei de Laubenfels, 1930). Haliclona xena de Weerdt, 1986, known previously only from western Europe (and where it is regarded as introduced from an unknown region) is here newly reported from the Tohoku coast of Honshu, as is Halisarca “dujardini Johnston, 1842”. Five species (Mycale macginitei, Hymeniacidon sinapium, Ute sp., Haliclona xena and Halisarca “dujardini”) were observed only once. Multiple lines of evidence (including lack of colonization by uniquely Eastern Pacific sponge species, the arrival in Hawai‘i of some of the same species whose only possible origin was Japan, and the low probability of coastal sponge larvae colonizing JTMD in the open ocean) indicate that the sponges on JTMD originate from the Western Pacific. Several species of sponges may have completed multiple generations on these long-distance rafts.