Ascandra polejaeffi sp. nov.

urn:lsid:zoobank.org:act: CC4802AF-E781-4130-8C05-C63FC49DAF8D

(Figs 5–6; Table 3)

Synonyms. Clathrina sp. nov. 10 Klautau et al. 2013: 452. Clathrina sp. nov. 11 Klautau et al. 2013: 452.

Etymology. For Poléjaeff, in recognition to his contributions to the taxonomy of calcareous sponges, many described from Eastern Brazil.

Material examined. Holotype — UFRJPOR 8805, Escalvada Island, 7.9 m depth, 05.iv.2017, colls. A. Padua and C. Leal . Paratype — UFRJPOR 6084, Ponta do Vidal, Reserva Biológica Marinha do Arvoredo, Santa Catarina, Brazil (27°17’52.3” S, 48°21’33.4” W), 10–15 m depth, 11.vii.2009, colls. F. Azevedo, J. Carraro and A. Padua .

Diagnosis. White Ascandra with mostly ramified cormus without water-collecting tubes. Skeleton composed of lanceolate diactines, one category of triactines and two categories of tetractines. The triactines are the most abundant spicule category.

Description. Cormus formed by large, mostly ramified but also irregular and loosely anastomosed tubes at the base and free at the apical region (Figs 5A, B). Colour white alive and beige in ethanol (Figs 5A, B). Consistency fragile. Surface of the tubes can be smooth or hispid at the base due to the longitudinally disposed diactines, which project the lanceolate tip outside the cormus. Aquiferous system asconoid.

Skeleton composed of diactines, present mostly at the base of the tubes, one category of triactines and two categories of tetractines, tetractine I being rare and tetractine II abundant (Figs 5C, D). Triactines are the most abundant spicules. Trichoxeas are also present all over the body.

Spicules (Fig 6; Table 3).

*From Klautau et al. (2022).

Diactines: Sinuous and slightly curved in the middle. One tip thicker and lanceolate and the other sharp (Fig 6A). Size: 168.9 (± 63.8)/ 11.1 (± 4.2) µm (N = 18).

Triactines: Regular. Actines slightly conical, with blunt tips (Fig 6B). Size: 166.0 (± 18.8)/ 16.3 (± 2.1) µm (N = 20).

Tetractines I: Regular. Basal actines conical and stout, undulated, with sharp tips (Fig 6C). Apical actine conical and curved at the tip, which is sharp. Size: basal actine—297.1 (± 46.3)/ 41.8 (± 6.6) µm (N = 17); apical actine— 117.1 (± 10.2)/ 17.1 (± 1.6) µm (N = 3).

Tetractines II: Regular to subregular. Basal actines cylindrical to slightly conical, distally undulated, with blunt tips (Fig 6D). Apical actine shorter than the basal ones and thick only at the base, then becoming very thin, smooth and with sharp tip, straight, curved or spiralled (Fig 6E). Size: basal actine—177.0 (± 19.8)/ 19.5 (± 2.2) µm (N = 20); apical actine—92.1 (± 17.2)/ 9.9 (± 2.0) µm (N = 20).

Ecology. The specimen was hanging inside a crevice on a vertical wall among other sponges and algae (Fig 5A).

Distribution. Southwestern Caribbean ecoregion— Panama, Caribbean Sea (Klautau et al. 2013). Eastern Brazil ecoregion—Guarapari, Espírito Santo State (type locality; present study). Southeastern Brazil ecoregion— Arvoredo Island, Santa Catarina State (Klautau et al. 2013).

Taxonomic remarks. Eight out of the 18 Ascandra species have diactines in the skeleton. Of these, the species that most resembles Ascandra polejaeffi sp. nov. is Ascandra mascarenica Klautau, Lopes, Tavares & Pérez, 2021 from La Réunion, Indian Ocean. Both species have identical skeleton composition, with one category of triactines, two categories of tetractines and lanceolate diactines. Overall measurements are also similar (Table 3), nevertheless, important differences were observed. For example, A. mascarenica has a cormus with anastomosed tubes that converge to a single osculum and triactines are rare, while the new species has a cormus mainly ramified, with several oscula, and triactines are the most abundant spicules. In addition, they separated in the phylogenetic reconstructions, hence, we name the specimens from the Atlantic as a new species.