Bidderia watremezi, Lopes & Pérez & Klautau, 2024

Lopes, Matheus Vieira, Pérez, Thierry & Klautau, Michelle, 2024, Cave-dwelling calcareous sponges (Porifera: Calcarea) from the Marquesas Islands, French Polynesia, Zoological Journal of the Linnean Society (zlae 138) 202 (3), pp. 1-29 : 9-12

Bidderia watremezi sp. nov.

( Figs 7, 8; Table 3 )

Zoobank registration: urn:lsid:zoobank.org:act:E3DEB4C0-C9CB-440C-9E61-3A0635C49C5E .

Type species: Bidderia bicolora Lopes et al., 2018 .

Diagnosis: White Bidderia with cortical skeleton exclusively composed of tripods, choanosomal and atrial skeletons composed of abundant tetractines and few small triactines. Sagittal spicules restricted to the oscular membrane. Subcortical skeleton absent.

Etymology: For Pierre Watremez, who passed away in December 2023.HewasthescientificmanageroftheAgencedesAiresMarines Protégées (today, French Biodiversity Agency) and devoted most of his energy to the deployment of oceanographic cruises designed to improve knowledge of marine biodiversity, particularly in underwater caves and the deep sea. He initiated the Pakaihi i te Moana programme in the Marquesas by carrying out several preparatory missions to get the Marquesans on board with the scientific objectives, and by providing the necessary facilities (boat, crew, and ROV), so that the scientists could simply concentrate on their task.

Type locality: The Four Caves, Nuku Hiva, Marquesas Islands, French Polynesia.

Type material: Holotype: French Polynesia, Marquesas Islands, Nuku Hiva: UFRJPOR 7519, The Four Caves (8°56.2 ʹ S, 140°07.2 ʹ W), 20 m depth, 11.i.2012, coll. T. Pérez, field number MQ2-GR-TP15.

Colour: White alive and in ethanol ( Fig. 7A, B).

Description: Sponge massive and lobate, each lobe has an apical osculum. Cormus formed by regular and tightly anastomosed tubes ( Fig. 7A–C). A cortical membrane covers the entire sponge ( Fig. 7D, E). Atrium hispid and delimited by endopinacoderm ( Fig. 7F). Aquiferous system solenoid. Oscular skeleton composed of sagittal triactines and tetractines, visibly a variation of the choanosomal spicules. Cortical skeleton with tripods similar to large regular triactines ( Fig. 7E). Surrounding the inhalant apertures, there are small, regular triactines of the same category of those present in the choanosome. Choanosomal and atrial skeletons composed of small, regular triactines and tetractines, with the latter being more abundant ( Fig. 7F).

Spicules ( Fig.8; Table 3 )

Tripods: Regular, similar to large triactines. Actines conical and straight, with blunt to sharp tips ( Fig. 8A). They are very rare. Size (UFRJPOR 7519): 107.8 (±20.1)/13.1 (±2.1) µm.

Triactines: Regular. Actines slightly conical to conical with blunt to sharp tips ( Fig. 8B). Size (UFRJPOR 7519): 52.6 (±5.5)/7.4 (±0.7) µm.

Tetractines: Regular. Basal actines similar to the choanosomal and atrial triactines ( Fig. 8C, D). The apical actine is conical, smooth, straight, with sharp tips ( Fig. 8D). Size (UFRJPOR 7519): 58.4 (±4.5)/6.4 (±1.1) µm (basal); 53.1 (±9.2)/4.9 (±0.7) µm (apical).

Ecology: The sponges were growing among polychaete tubes ( Fig. 7C).

Geographical distribution: Currently endemic to the type locality. Ecoregion : Marquesas .

Remarks: The genus Bidderia currently has two accepted species: Bidderia bicolora Lopes et al., 2018 from the Caribbean and Bidderia amitsba ( Hôzawa, 1929) from Japan. Bidderia watremezi sp. nov. can be distinguished from Bidderia bicolora by the presence, in the latter, of a subcortical skeleton formed by sagittal triactines and larger spicules [holotype: tripods: 233.7 (±19.3)/22.1 (±4.0) µm; triactines: 99.5 (±8.6)/8.8 (±0.7) µm; tetractines: 98.0 (±7.4)/9.1 (±0.7) µm (basal), 74.4 (±11.7)/5.5 (±0.3) µm (apical)]. Moreover, spicules are slightly conical to conical in Bidderia watremezi sp. nov. and slightly conical to cylindrical in Bidderia bicolora .

Bidderia watremezi sp. nov. can be distinguished from Bidderia amitsba because of the presence of rare tetractines in the atrial skeleton of the latter, while in the new species they are very abundant. The shape and size of the spicules are also different, being cylindrical and larger in Bidderia amitsba (tripods: 220– 500/20–30 µm; triactines and basal actines of tetractines: 100– 160/8–10 µm; apical actine of tetractines: 60–150/4–6 µm) and slightly conical to conical in Bidderia watremezi sp. nov. [tripods: 107.8 (±20.1)/13.1 (±2.1) µm; triactines: 52.6 (±5.5)/7.4 (±0.7) µm; tetractines: 58.4 (±4.5)/6.4 (±1.1) µm (basal); 53.1 (±9.2)/4.9 (±0.7) µm (apical)].

It is worth mentioning that B. watremezi sp. nov. strongly resembles Leucascus digitiformis ( Klautau et al. 2020: 276) . Both species have a similar cormus and same skeleton composition. Nevertheless, we did not see spines on the apical actines of tetractines in Bidderia watremezi sp. nov., whereas in Leucascus digitiformis they are abundant and well-developed. The tripods are also larger and thicker in the former ( Table 3 ). We unfortunately did not succeed in getting a DNA sequence of both specimens to infer their phylogenetic relationship. Considering the mentioned morphological differences, we tentatively place this species in the genus Bidderia , due to the lack of spines in the apical actines of tetractines, and as a new species.