Rowella connectens, (BRONDSTED, 1926) COMB., 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 : 719-722

ROWELLA CONNECTENS ( BRØNDSTED, 1926) COMB. NOV.

( FIGS 15, 16; TABLE 8)

Synonyms: Leucandra connectens – Brøndsted, 1926: 308; Burton, 1963: 552.

Type specimen: Five syntypes under the same voucher (NHMD-633253).

Type locality: Cape Maria van Diemen, Northland, New Zealand (34°24ʹ S, 172°30ʹ E; inaccurate coordinates). Three Kings–North Cape MEOW ecoregion.

Description: Sponge body tubular and digitate ( Fig. 15A). Colour cream in ethanol. Consistency incompressible but slightly soft to the touch. Outer surface smooth. Cortex with multiple small inhalant apertures, giving it a porous appearance. Oscula present at the apical region of the tubes. They are simple slits or circular and surrounded by membrane with specific skeleton ( Fig. 15B). Body wall thick, tapering towards the top and base of the sponge. Atrial cavity narrow and slightly hispid due to the apical actine of tetractines. Aquiferous system leuconoid with spherical choanocyte chambers ( Fig. 15C).

Skeleton: The oscular margin has sagittal triactines and tetractines, which gradually become regular as the body wall thickens ( Fig. 15B). The cortical skeleton is well developed, although it is not as thick as the choanosome ( Fig. 15C). The cortical skeleton has several layers of tangential triactines and few tetractines, which project their apical actine into the choanosome, but never reaching the atrium ( Fig. 15D). The choanosomal skeleton is comprised of large triactines and pygmy triactines and tetractines, mostly present around the canals. The pygmy spicules are also present in the atrium, laying tangentially ( Fig. 15E), with pygmy tetractines being more abundant and projecting their apical actine into the atrial cavity.

Spicules ( Table 8):

Cortical triactines ( Fig. 16A). Regular. Variable sizes. Actines are cylindrical to slightly conical, straight or slightly undulated in the middle portion. Tips are blunt. Size – 313.5 (± 77.5) μm length/24.5 (± 7.7) μm width.

Cortical tetractines ( Fig. 16B). Regular. Basal actines are conical, slightly undulated, with blunt to sharp tips. The apical actine is slightly conical, straight and smooth, with blunt to sharp tips. It is frequently longer than the basal actines. These spicules are less abundant and bigger than the cortical triactines. Size – basal actines: 376.7 (± 83.7) μm length/38.3 (± 3.6) μm width; apical actine: 1,042.6 (± 172.2) μm length/47.1 (± 7.0) μm width.

Choanosomal and atrial triactines ( Fig. 16C). Regular. Pygmy. Actines are conical and straight, with blunt to rounded tips. They are less abundant than the tetractines in the atrium. Size – 44.5 (± 9.1) μm length/6.6 (± 1.7) μm width.

Choanosomal and atrial tetractines ( Fig. 16D). Regular. Pygmy. Basal actines are conical and straight, with blunt to rounded tips. The apical actine is conical, smooth, blunt and straight or slightly curved at the distal part. Size – basal actines: 46.8 (± 6.8) μm length/6.7 (± 6.7 μm) width; apical actine: 49.6 (± 7.4) μm length/6.6 (± 1.1) μm width.

Ecology: Two specimens were found attached to rock boulders with colonial bryozoans, barnacles, calcareous tubes of polychaetes and algae. They were collected by dredging at 92 m depth.

Geographical distribution (MEOW ecoregion): Three K i n g s–N o r t h C a p e (C a p e M a r i a v a n D i e m e n, Northland, New Zealand – Brøndsted, 1926).

Remarks: Brøndsted (1926) stated having difficulties assigning this species to any other genus of Calcarea. He mentioned that this species had a classification between Leucandra Haeckel, 1872 and Leucilla Haeckel, 1872 (Calcaronea) . The species was then placed in Leucandra due to the absence of the typical inarticulate skeleton of Leucilla and for having a disorganized choanosomal skeleton ( Brøndsted, 1926).

If Brøndsted had considered the synapomorphies of Calcinea and Calcaronea (subclasses not accepted by some authors at the beginning of the 20 th century), he would have noticed that Leucandra connectens is, in fact, a calcinean sponge. In addition, considering the pygmy spicules present in the choanosome, the well-developed cortical skeleton and the body shape of this sponge, he would see that his species should be placed in the genus Leucettusa sensu Dendy & Row, 1913 .

Burton (1963) was the only one who analysed this species after its original description. Even though Burton equivocally proposed its synonym with Leucettusa corticata , he drew attention to the fact that Leucandra connectens is not a Leucandra and that it is related with Leucaltidae sensu Dendy & Row, 1913 . Following Burton’s idea, and after the re-analysis of the type specimens of Leucandra connectens , we propose the new combination RoƜella connectens .

In this species, in addition to the pygmy spicules, large cortical triactines are also present in the choanosome. This trait is also observed in R. imperfecta and R. tubulosa , but they have cortical tetractines often composing the choanosomal skeleton, instead of triactines. Moreover, these large cortical spicules are abundant in the choanosome of R. connectens , opposing to their occasional presence in R. imperfecta and R. tubulosa .