Integrative taxonomic re-description of Halisarca magellanica and description of a new species of Halisarca (Porifera, Demospongiae) from Chilean Patagonia

A series of recent expeditions in fjords and canals of Southern Chilean Patagonia allowed the re-collection of Halisarca magellanica Topsent, 1901 and the discovery of a new species, Halisarca desqueyrouxae sp. nov. The material studied was collected at depths ranging from 3 to 30 m at latitudes comprised between 42° and 49°S. Both species share the same habitat and show a morphological plasticity, but differ in their colour. Halisarca magellanica is bright pink to whitish with three morphs whereas H. desqueyrouxae sp. nov. is light brown to beige with two morphs. An extensive investigation in TEM and SEM reveals several differences among cell types with inclusions between both species. Three distinct spherulous cells occur. Type 1 is shared by both species, Type 2 is occasional in H. magellanica but absent from H. desqueyrouxae sp. nov. Type 3 is rare in H. magellanica and occurs abundantly in half of the specimens of H. desqueyrouxae sp. nov. Granular cells are shared by both species but do not occur in all specimens. Microgranular cells are characteristic of H. magellanica. Both species also clearly differ by their endobiotic bacteria. Phylogenetic analysis of cox1 sequences places H. magellanica as a sister group to all other previously published Halisarca species sequences (9.1–9.7% difference) except H. harmelini, while H. desqueyrouxae sp. nov. is placed as a sister group to H. dujardini (2.3% difference).

Molecular and morphological description of a new species of Halisarca (Demospongiae: Halisarcida) from Mediterranean Sea and a redescription of the type species Halisarca dujardini

Halisarca harmelini sp. nov. is described from the northwestern Mediterranean Sea at depths between 15–65 m from coralligenous rocks. The new species occurs as thin sheets only on the bryozoan Smittina cervicornis. Morphologically, it is characterized by its thin layer architecture, skin-like, lusterless and smooth surface, a soft, very delicate and easily torn texture, and pale-yellow colour. At the cytological level H. harmelini is characterized by a complex of cells with inclusions: spherulous, vacuolar, granular, microgranular and rhabdiferous cells. The new species is clearly different in cell and endobiotic bacteria content and in external morphology from all previously described species of Halisarca. In addition to the description of the new species, we have conducted a thorough ultrastructural investigation and re-described the type species Halisarca dujardini Johnston, 1842 using specimens from different region of the North Atlantic, Arctic and North Pacific. To investigate the relationships between H. harmelini and H. dujardini on the molecular level, we determined the complete mitochondrial DNA (mtDNA) sequences of the new species of Halisarca and compared it with that of H. dujardini. The two mitochondrial genomes are identical in gene content and gene arrangement but differ in size by ~1,300 bp (6.8%). The overall genetic distance between coding sequences is 0.1, much greater than what has been previously reported for individual species of non-bilaterian animals. The latter observation supports the new species status of H. harmelini.

A new species of Oscarella (Demospongiae: Plakinidae) from the Western Sea of Japan

Oscarella malakhovi sp. nov. is described from the waters of Peter the Great Bay (northwestern Sea of Japan, Russia) at depths between 0.4–4 m from a rocky coast. This is the first record of the genus Oscarella from the North-Western Pacific. The new species is characterized by its pinky-beige to yellow color, undulating appearance, lumpy, microlobate surface, soft, slimy consistency, two particular kinds of cells with inclusions (vacuolar and granular cells), and of two kinds of endobiont bacteria. The new species of Oscarella is clearly different in cell, endobiotic bacteria content, and external morphology from all previously described species of Oscarella.