Clathrina williamsi, Klautau & Lopes & Tavares & Rizzieri & Sorokin & Fromont & Goudie & Crowther & McCormack & George & Wahab, 2025

Clathrina williamsi View in CoL sp. nov.

( Fig. 4; Table 2)

Zoobank registration: urn:lsid:zoobank.org:act:

Etymology: For Alan Williams (CSIRO, Australia), deep sea ecologist who led the seafloor biodiversity team that collected these sponges.

Diagnosis: Clathrina with tightly anastomosed tubes and three categories of triactines: one larger, conical, and rare and the other two smaller, cylindrical to slightly conical, and abundant. Cells with granules are present.

Type material: Holotype, SAMA S1885, GAB, 34°17 ʹ 30″S, 132°42 ʹ 24″E, depth: 283 m, coll. Great Australian Bight Research Program ( GABRP), site IN2015 _C02_181, 7 December 2015 GoogleMaps . Paratype, SAMA S3682, collection details same as holotype.

Colour: Beige to light brown in ethanol ( Fig. 4A).

Morphology and anatomy: Sponge amorphous. Cormus formed by thin, irregular, and tightly anastomosed tubes ( Fig. 4A). One closed tube was observed at the apical region. It is, perhaps, a water-collecting tube. Aquiferous system asconoid. Cells with granules were observed.

Te skeleton is composed of three categories of triactines ( Fig. 4B). Tere are orange embryos inside the cormus ( Fig. 4C). Te category with conical actines is rare. Tis category is always present on the surface of the tubes ( Fig. 4B). Te other two categories have cylindrical actines. Te category with the thinnest actines is the most abundant ( Fig. 4D).

Spicules ( Table 2)

Triactine I: Regular (equiangular and equiradiate). Rare. Actines are stout, with sharp tips ( Fig. 4E). Size: 237.4 (±67.4)/24.0 (±6.8) µm.

Triactine II: Regular (equiangular and equiradiate). Actines are cylindrical to slightly conical, with sharp tips ( Fig. 4F). Size: 197.3 (±38.1)/12.1 (±1.3) µm.

Triactine III: Regular (equiangular and equiradiate), but it is common to find spicules with one actine shorter or larger than the others. Tis is the most abundant category. Actines are cylindrical, with sharp tips. Tey are frequently undulated ( Fig. 4G). Size: 134.8 (±17.5)/7.6 (±0.9) µm.

Geographical distribution: Currently known only from the type locality.

Ecology: Tis species was found at a depth of 283 m on the edge of the continental shelf (in fine sand and silt), associated with radiolarians, shrimps, and polychaetes.

Taxonomic remarks: Tere are three species of Clathrina with threecategoriesoftriactines: Clathrinadelicata Fontana, Cóndor-Luján, Azevedo, Pérez & Klautau, 2018 from Martinique, Clathrina laminoclathrata Carter, 1886 from South Australia, and Clathrina nuroensis Azevedo, Cóndor-Luján, Willenz, Hajdu, Hooker & Klautau, 2015 from Peru. Clathrina delicata has large and loosely anastomosed tubes, whereas the new species has thin and tightly anastomosed tubes. Clathrina laminoclathrata and C. nuroensis do not have spicules with cylindrical actines. All the three categories of triactines have conical actines, whereas the new species has one category with conical actines and the other two with cylindrical actines.