A new species of glass sponge (Hexactinellida: Sceptrulophora: Uncinateridae) from the Weijia Seamount in the northwestern Pacific Ocean.

In this article we report on a hexactinellid sponge new to science, Tretopleura weijicus sp. nov., which was collected from the Weijia Seamount in the northwestern Pacific Ocean at a depth of 1995 m. Its blade-like and branching body form, the primary choanosomal framework consisting of multiaxial longitudinal strands without synapticula, and the presence of sceptrules suggest placement within the family Uncinateridae Reiswig, 2002, which is also supported by molecular phylogenetic evidence from COI and 16S sequences. The absence of swollen dermal spurs or regular pentactins and the presence of two types of discohexasters characterize it as a new species. More specimens should be collected to revise the generic characters.

A new glass sponge genus (Hexactinellida: Euplectellidae) from abyssal depth of the Yap Trench, northwestern Pacific Ocean.

In this article we report on a hexactinellid sponge new to science, Rhizophyta yapensis gen. et sp. nov., which was collected from the Yap Trench in the northwestern Pacific Ocean at an abyssal depth of 4159-4779 m. Its fungus-like body form with long peduncle and absence of hypodermalia suggest placement within the euplectellid subfamily Bolosominae Tabachnick, 2002, whereas molecular phylogenetic evidence suggests that it is sister to all remaining Euplectellidae Gray, 1867. Its rhizophytous method of attachment to the substrate, hitherto unknown from bolosomine Euplectellidae, a veil of pentactins covering the peduncle, and the presence of toothed discohexasters as the only type of microscleres, clearly characterize it as a new genus. The intraspecific divergence between holotype and paratypes of the new species is examined with both morphological and molecular approaches. This report represents the first record of a hexactinellid sponge from the Yap Trench.

A new species in the genus Styracaster (Echinodermata: Asteroidea: Porcellanasteridae) from hadal depth of the Yap Trench in the western Pacific.

Styracaster yapensis sp. nov. is reported from the Yap Trench in the western Pacific from hadal depths between 6377-6575 m, which is among the deepest known occurrence of a species in this genus. It is distinguished from other Styracaster species by its abactinal surface armature and rudimentary cribriform organs. This paper provides a description of the new species along with detailed photos. The intraspecific differences between the holotype and paratype of the new species are examined with molecular and morphological approaches.