Cave-dwelling calcareous sponges (Porifera: Calcarea) from the Marquesas Islands, French Polynesia Author Lopes, Matheus Vieira Federal University of Rio de Janeiro, Biology Institute, Zoology Department, TaxoN Laboratory, Avenue Carlos Chagas Filho 791, CEP 21941 - 599, Rio de Janeiro, Brazil Author Pérez, Thierry Institut Méditerranéen de Biodiversité et d’Ecologie marine et continentale, CNRS, Aix-Marseille Université, IRD, Université d’Avignon, Station Marine d’Endoume, Chemin de la Batterie des Lions, 13007 Marseille, France Author Klautau, Michelle Federal University of Rio de Janeiro, Biology Institute, Zoology Department, TaxoN Laboratory, Avenue Carlos Chagas Filho 791, CEP 21941 - 599, Rio de Janeiro, Brazil mklautau@biologia.ufrj.br text Zoological Journal of the Linnean Society 2024 zlae 138 2024-11-06 202 3 1 29 https://doi.org/10.1093/zoolinnean/zlae138 journal article 10.1093/zoolinnean/zlae138 0024-4082 681F645-F70D-4E1F-BF7F-D0251528BD51 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. Figure 4. Maximum likelihood phylogenetic tree of the C-LSU of Calcaronea . Sequences generated in the present work are in bold. The clade of aliactine-bearing sponges is presented shaded. Bootstrap values are shown at the nodes (<means value below 60%). Tree rooted with Leucosolenia and Achramorphidae + Baeriida. Figure 5. Morphology of the holotype of Borojevia moana sp. nov. ( UFRJPOR 7524 ). A, specimens in situ encrusting the surface of a rock (no scale available). B, detail of the anastomosis of the holotype. C, section of a thicker part of the body evidencing the spaces between anastomosed tubes (*). D, tangential section of the body surface. 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). Figure 6. Spicules of the holotype of Borojevia moana sp. nov. ( UFRJPOR 7524 ). A, tripod. B, triactine. C, tetractine. D, two types of apical actines, one smooth (arrow head) and the other with spines (arrow). 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.