Haliclona (Flagellia) xenomorpha: A new species of Heteroscleromorph Demosponge from the Gulf of St. Lawrence, Canada.

Demosponges are the most abundant class of Poriferans in modern waters, with 72% of living Sponge species being Demosponges. They are characterised by a soft body covering a skeleton made up of spicules of calcite or aragonite. Members of the subclass Heteroscleromorpha also have silica spicules, but these are morphologically distinct from those of Glass Sponges, taking the form of monaxons (needle shaped spicules) and/or tetraxons (four-pointed spicules), as well as microscleres (small skeletal elements which are often highly distinctive at species level). The order Haplosclerida consists of Heteroscleromorph Sponges with skeletons comprised largely of oxeas monaxons pointed at both ends) and strongyles (monaxons with blunt ends), plus distinctive microscleres. The family Chalinidae are common marine encrusting Haplosclerid Sponges, found in protected environments as undersides of rocks and crevices, both in intertidal and subtidal habitats. The largest genus in the family Chalinidae is Haliclona, which contains over 350 species, and has been divided into numerous subgenera. Haliclona (Flagellia) is a recently erected subgenus characterized by the presence of flagellosigma microscleres (small, horseshoe-shaped spicules), which are often distinctive between species. Members of the taxon also have normal sigmas within a confused skeleton formed by oxea megascleres. The subgenus has a global distribution and contains 10 species. 

In a paper published in the journal Zootaxa on 14 May 2020, Curtis Dinn of the Gulf Fisheries Centre of Fisheries and Oceans Canada, describes a large and abundant new species of Haliclona (Flagellia) collected throughout the southern Gulf of St. Lawrence, Canada.

The new species is named Haliclona (Flagellia) xenomorpha, where 'xenomorpha' means 'Alien-shaped' in reference to the thick and often irregular flagellosigmas. These spicules also resemble the derelict spacecraft from the 1979 film Alien directed by Ridley Scott, and the name pays homage to the titular antagonist of the series. This species is massively encrusting with raised oscula (large openings to the outside through which the current of water exits after passing through the spongocoel, having been absorbed through much smaller dermal pores). The Sponge is very friable and is thus often broken into pieces upon collection. The largest specimens are over 10 cm in diameter, but no consistent growth form is apparent. Larger specimens are often seen fully encrusting small pebbles and may have shell fragments incorporated into the tissue. The surface is generally smooth in more intact specimens, while fragments are more irregular and porous. In less damaged specimens, a fine transparent mesh covers the surface, but this often collapses after collection. Oscula are less than 0.5 cm wide and are raised above the surrounding tissue. Below the surface, the Sponge tissue is irregularly punctate. The consistency of large pieces is firm, compressible, but very brittle if pressure is applied, resulting in small crumbled pieces. The colour is pale yellow to light brown, with some specimens appearing pinkish.

Haliclona (Flagellia) xenomorpha. (A). Holotype ARC 81426. (B) Paratype ARC 81428 showing portions of smooth surface. (C) Specimen with smooth surface along an inner portion. (D) Large multispecies catch with Haliclona (Flagellia) xenomorpha (white arrows) and Mycale lingua (black arrows). (E), (F) Skeleton. Dinn (2020).

The skeleton of Haliclona (Flagellia) xenomorpha is confused, with a loose reticulation of paucispicular tracts which are irregularly connected by single spicules. Thick and thin oxeas do not appear to be localized in the skeleton. There is no surface specialization of spicules, but a layer of thick spongin is present at the surface in undamaged specimens. Flagellosigmas and sigmas are found throughout the choanosome, with regular sigmas often occurring in groups, especially evident near canal openings.

Megascleres (large spicules) are oxeas in two size categories. Thick oxeas are often slightly bent and have sharp tapered points, 250-298 × 12-17 μm. Thin oxeas are similarly shaped but with sharper ends which taper further along the shaft, 183-245 × 3.6-9.0 μm. Microscleres are flagellosigmas in two size categories and abundant normal sigmas. The distinctive thick category of flagellosigmas consists of spicules with curved ends that may be steeply curved, branched into two or more points, or not curved at all with endings pointing outwards, length of long endings 56-108 μm, of short endings 46-73 μm, width 58-98 μm, thickness 6.5-13 μm. Normal flagellosigmas are ovoid with widely curved ends, but are variable in size and overall shape, length of long endings 32-95 μm, of short endings 26-56 μm, width 40-77 μm, thickness 2.7-5.6 μm. Regular sigmas are variable in size, and have incurved apices, 39-82 μm in length and 3.2-7.1 μm thick. In some specimens thick flagellosigmas may appear more sigma-like with ends of similar lengths and a crescent shape, but these spicules may also have irregular ends.

Haliclona (Flagellia) xenomorpha, spicules. (A)–(B). Oxeas. (C)–(F) Thick flagellosigmas showing various degrees of irregularity. (G)–(H) Regular flagellosigmas. (I)–(J) Regular sigmas. Dinn (2020).

Several specimens of Haliclona (Flagellia) xenomorpha were collected along the American Bank near the Gaspé Peninsula and southern fringe of the Laurentian Channel. The holotype (when describing a new species one specimen is designated the holotype; all future specimens determined to belong to the same species as this holotype therefore bellong to the species) was collected north of Brion Island, in the Magdalen Island Archipelago, near the shelf edge and was encrusting a rock. The species was collected at depths ranging from 41–89 m. Multiple specimens were collected in single trawls, but only single individuals from trawls were retained for taxonomic analysis.

The unique features of Haliclona (Flagellia) xenomorpha are the presence of thick flagellosigmas and two categories of oxeas. The thickness of the flagellosigma spicules exceed, and in most cases more than double the maximum thickness of spicules from other members of the genus. The flagellosigmas in Haliclona (Flagellia) xenomorpha reach a maximum thickness 13 μm, while flagellosigmas of Haliclona (Flagellia) porosa (also present in the Gulf of St. Lawrence) reach a maximum thickness of 6.3 μm. Thick flagellosigmas are common in the skeleton, and are thus considered as a second size category, though there may be intermediately sized flagellosigmas which are difficult to place in either size category. The consistently irregular endings of the thick flagellosigmas are also a defining character of the species.

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Two new species of Chalinid Dermosponge from Western Australia.

Chalinid Dermosponges are among the hardest Sponges to classify taxonomically due to their simple anatomies and variable morphologies. They are encrusting Sponges with skeletons made up of individual spicules which support their structure, but are not helpful taxonomically. Species are often distinctively coloured, but this is not visible in preserved specimens, making comparison to museum specimens extremely difficult. Chalinid Dermosponges are found globally and at all depths, but are most abundant and diverse in shallow subtidal waters (i.e. just below the low-tide level).

In a paper published in the journal Zootaxa on 9 July 2014, Jane Fromont of the Aquatic Zoology Department at the Western Australian Museum and David Abdo of the Marine Ecology and Monitoring Section of the Department of Fisheries of the Government of Western Australia describe two new species of Chalinid Dermosponge from temperate coastal waters off the coast of Western Australia, both of which are placed in the genus Haliclona.

The first new species is named Haliclona djeedara, which means 'brown' in the Nyoongar language, spoken by the indigenous people of south Western Australia. Haliclona djeedara is an erect, lobate, encrusting Sponge, light brown or beige in colour. It is firm, but compressible with a springy texture and large internal canals. It was found living on limestone reefs at depths of 3-30 m, in temperate waters south of 30˚ south, from Jurien Bay in the north to Bremer Bay in the south. It was observed giving birth to cylindrical parenchymellae larvae (planktonic Sponge larvae consisting of clumps of ciliated cells) in February, which is summer in Western Australia. The individual Sponges are gonochoric (sexed, can be male or female).

Underwater image of Haliclona djeedara. David Abdo in Fromont & Abdo (2014).

The second new species is named Haliclona durdong, meaning 'green' in the Nyoongar language. Haliclona durdong is an erect or massive Dermosponge with a smooth, velvety surface. It is compressible and easily damaged. It was found living on limestone reefs at depths of 3-30 m, in temperate waters south of 30˚ south, from Jurien Bay in the north to Bremer Bay in the south. It gives birth to to cylindrical parenchymellae larvae in the summer; individuals can apparently be gonochoric or hermaphroditic. 

Underwater image of Haliclona durdong. David Abdo in Fromont & Abdo (2014).

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