Rowella dictyogaster, (ROW & HOZAWA, 1931), Lopes & Klautau, 2023

Lopes, Matheus Vieira & Klautau, Michelle, 2023, Phylogeny and revision of Leucaltis and Leucettusa (Porifera: Calcarea), with new classification proposals and description of a new type of aquiferous system, Zoological Journal of the Linnean Society 198, pp. 691-746 : 722-724

ROWELLA DICTYOGASTER ( ROW & HÔZAWA, 1931) COMB. NOV.

( FIG. 17; TABLE 9 )

Synonyms: Leucettusa dictyogaster – Row & Hôzawa, 1931: 751; Burton, 1963: 576; non Leucettusa dictyogaster – Dendy & Row, 1913: 739; Dendy, 1924: 280 (nomen nudum).

Type specimen: Holotype (Tokyo Science Faculty Spec. No. BC) possibly lost.

Type locality: Koombana Bay, Bunbury, Western Australia (22°29ʹ S, 113°57ʹ E). Leeuwin MEOW ecoregion.

Material examined: Original description.

Description: Sponge massive and amorphous with a single osculum atop ( Fig. 17A). Colour greyish in ethanol. Consistency hard outside and soft inside. Outer surface smooth and uneven with few depressions. Osculum oval with a membrane. Body wall thick, tapering towards the top and the base of the

REVISION OF LEUCALTIS AND LEUCETTUSA 723

sponge. Atrial cavity narrow and slightly hispid due to the apical actine of the atrial tetractines. Many visible excurrent canals reach the atrial surface. Aquiferous system leuconoid with oval to spherical choanocyte chambers and lacunar canals.

Skeleton: The oscular margin has sagittal triactines, which possibly derive from the regular cortical triactines ( Fig. 17B). Cortical skeleton well developed, comprised of several layers of tangential triactines and microdiactines. No spicules were mentioned for the choanosomal region. Atrial skeleton comprised of pygmy tetractines.

Spicules ( Table 9 ):

Cortical microdiactines ( Fig. 17C). Cylindrical, sinuous and curved. Both tips are sharp; however, one is fusiform, while the other is arrow-shaped. Size – 30.0–130.0 μm length/6.0–10.0 μm width.

Cortical triactines ( Fig. 17D). Regular. Actines are cylindrical, with sharp tips. Size – 380.0–580.0 μm length/30.0–50.0 μm width.

Atrial tetractines ( Fig. 17E). Sagittal. Pygmy. Basal actines are conical, with sharp tips. The paired actines are slightly shorter than the unpaired one. The apical actine is long, conical, smooth, slightly curved, with sharp tips. Size – paired actine: 20.0–40.0 μm length/6.0 μm width; unpaired actine: 30.0–50.0 μm length/8.0 μm width; apical actine: 100.0–120.0 μm length/8.0 μm width.

Ecology: No information available.

Geographical distribution (MEOW ecoregion): Leeuwin (Koombana Bay – originally Bunbury Bay – Bunbury, Western Australia – Row & Hôzawa, 1931).

Remarks: Row & Hôzawa (1931) described Leucettusa dictyogaster after five specimens collected in Bunbury Bay, Western Australia. Curiously, prior to the species description, this species was mentioned in the systematic review of Dendy & Row (1913) without any description other than the aquiferous system. The specimens used for the species description are lost but, since it possesses a massive body and pygmy spicules, we propose to transfer it to the new genus RoƜella .

One unique character of R. dictyogaster is the presence of microdiactines in the cortical skeleton. These spicules are commonly found in the subclass Calcaronea and rare in calcinean species (e.g. Ascandra minchini Borojević, 1966 ). Although they could be considered a contamination, they were mentioned by Row & Hôzawa (1931) as being present in all the five specimens analysed. Therefore, we consider microdiactines part of this species.

Disregarding these spicules, the skeleton of R. dictyogaster is simple. The only categories found are the cortical triactines and the atrial tetractines. Oscular triactines are considered modified cortical triactines. We have confirmed that some categories, mostly pygmy spicules, are often overlooked in this group of species possibly because of the size and, sometimes, low abundancy. It is also possible that R. dictyogaster has rare tetractines in the cortex and scattered pygmy spicules in the choanosome. It is necessary to re-analyse specimens from Bunbury to check these spicules and properly perform taxonomic comparisons with other RoƜella species.