Rowella vera 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 : 738

ROWELLA VERA ( POLÉJAEFF, 1883) COMB. NOV.

( FIG. 28; TABLE 15 )

Synonyms: Leucetta Ʋera – Poléjaeff, 1883: 68; Leucettusa Ʋera – Dendy & Row, 1913: 739; Burton, 1963: 557; Borojević & Grua, 1965: 11. Leucilla Ʋera – Fell, 1950: 10.

Type specimen: Holotype ( BMNH 1884.4 .22.60).

Type locality: Off Kerguelen Island , South Indian Ocean (49°30ʹ S, 70°30ʹ E). Kerguelen Islands MEOW ecoregion .

Description: The holotype is only a small fragment ( Fig. 28A, B). Colour light beige (surface) and brown (mesohyl) in ethanol. Compressible and soft to the touch. Outer surface smooth. Atrial surface hispid due to the apical actines of tetractines. Osculum could not be seen. Body wall thick. Atrial cavity spacious with conspicuous excurrent canals. Aquiferous system peculiar: near the cortex (one-third of the body wall) the choanocyte chambers are elongated and cylindrical (syconoid), while near the atrial surface (other twothirds) they are subspherical (leuconoid) ( Fig. 28C). Large granular cells found surrounding the canals. Few young oocytes present in the holotype.

Skeleton: Oscular margin with sagittal triactines that gradually become regular as the body wall thickens. Cortical skeleton well developed, although not as thick as the choanosome. It is comprised of several layers of tangential triactines and tetractines ( Fig. 28C). The apical actine of the cortical tetractines crosses the choanosome, sometimes penetrating the atrium. The choanosomal skeleton is comprised of pygmy triactines and tetractines, mostly present around canals. These spicules are also present in the atrium, laying tangentially, with pygmy tetractines being more abundant and projecting their apical actine into the atrial cavity.