Ascoleuceta globularis, Klautau & Lopes & Tavares & Rizzieri & Sorokin & Fromont & Goudie & Crowther & McCormack & George & Wahab, 2025

AscoleuceTa globularis sp. nov.

( Figs 11, 12; Table 6)

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

Etymology: For the globular shape of the body.

Diagnosis: Ascoleuceta with a globular body and single osculum. Cortex with large and small triactines. Choanocyte tubes with small tetractines and some small triactines. Atrial skeleton composed of small triactines and tetractines.

Type material: Holotype, SAMA S1861, GAB, 35°02 ʹ 17″S, 134°05 ʹ 42″E, depth: 221 m, coll. GABRP, site IN2015 _ C02_128, 4 December 2015 GoogleMaps . Paratype, SAMA S1876, GAB, 34°16 ʹ 33″S, 132°41 ʹ 29″E, depth: 209 m, coll. GABRP, IN2015 _ C02_179, 7 December 2015 GoogleMaps . SAMA S1909, GAB, 33°25 ʹ 04″S, 131°02 ʹ 26″E, depth: 218 m, coll. GABRP, site IN2015 _ C02_191, 8 December 2015 GoogleMaps .

Additional material examined: SAMA S1895, SAMA S1896, GAB, 34°17 ʹ 30″S, 132°42 ʹ 24″E, depth: 283 m, coll. GABRP, site IN2015_C02_181, 7 December 2015. SAMA S1907, GAB, 33°25 ʹ 04″S, 131°02 ʹ 26″E, depth: 218 m, coll. GABRP, site IN2015_C02_191, 8 December 2015.

Colour: Beige or light grey in ethanol ( Fig. 11A, B).

Morphology and anatomy: Sponge globular to subglobular, formed by irregular and tightly anastomosed tubes in the cortex ( Fig. 11A) and by larger and less anastomosed tubes internally ( Fig. 11B). Near the cortex, the tubes run in parallel to each other in the direction of the atrium ( Fig. 11C). In some areas of the cortex, the anastomosis is so tight that it is almost continuous. Tere are several specimens of this species. In some of them it was possible to recognize a small, simple apical osculum with a small cavity, with a delicate membrane, below it. Aquiferous system solenoid.

Te cortex is composed of large and small triactines ( Fig. 11D). Tey are randomly spread, not organized. No ornamentations were found. In the choanocyte tubes there are small triactines and tetractines, the later being more abundant ( Fig. 11E). Te atrial skeleton is composed of approximately the same proportion of small triactines and tetractines ( Fig. 11F). Tese atrial spicules appear to be slightly bigger than those of the choanocyte tubes.

Spicules ( Table 6)

Large triactines: Regular (equiangular and equiradiate). Actines are conical to slightly conical, with blunt tips ( Fig. 12A). Size: 259.1 (±28.9)/20.5 (±3.7) µm.

Small triactines: Regular (equiangular and equiradiate). Actines are cylindrical, with blunt tips ( Fig. 12B). Size: 139.9 (±29.3)/8.7 (±1.1) µm.

Small tetractines: Regular (equiangular and equiradiate). Actines are cylindrical, with blunt tips ( Fig. 12C). Te apical actine is very thin (needle-like), smooth, frequently undulated, with a sharp tip ( Fig. 12D). Size: basal, 135.1 (±15.6)/8.9 (±1.2) µm; apical, 81.8 (±33.9)/5.7 (±1.2) µm.

Geographical distribution: Currently known from four localities in the GAB.

Ecology: Tis species was found in depths ranging from 209 to 283 m on the edge of the continental shelf (in fine sand and silt). Tere was a shrimp found inside specimen SAMA S1876 and bryozoans found inside specimen SAMA S1861. Two crustaceans were found in the atrium of specimen SAMA S1896, and a bryozoan was also found atached to the outside of this specimen.

Remarks: Ascoleuceta globularis can be differentiated easily from Ascoleuceta compressa and Ascoleuceta oentricosa by the shape of the actines of the small spicules, which are cylindrical in the new species and conical in the other two. Te new species is much more similar to the previous described species, Ascoleuceta gabensis . Although similar in the globular shape and in the spicular composition, the large triactines of Ascoleuceta gabensis are much larger than in Ascoleuceta globularis ( Ascoleuceta gabensis , 512.4/53.8 µm; Ascoleuceta globularis , 259.1/20.5 µm). In addition, very large triactines are present in the cortex of Ascoleuceta gabensis , in the choanocyte tubes, and in the atrial skeleton, whereas in Ascoleuceta globularis the larger triactines are restricted to the cortex. Another important difference is the presence of tetractines in the atrial skeleton of the present species, whereas Ascoleuceta gabensis has only triactines surrounding the atrium.