Abstract
Lithistid demosponges are well known from limestone caves of karstic origin in the Mediterranean Sea. However, they have never been reported from submarine caves of volcanic origin in the South Pacific. Here, we describe and provide DNA barcodes for four new lithistid demosponges including one new genus. All species grew on basaltic rocks inside lava tubes on Nuku Hiva Island (Marquesas Islands) and Tahiti Iti peninsula on Tahiti Island (Society Islands) in French Polynesia. Three of the species have rhizoclone desmas as choanosomal skeletons and belong to the family Scleritodermidae (Microscleroderma miritatarata sp. nov. and Microscleroderma lava sp. nov.) and Siphonidiidae (Gastrophanella basaltica sp. nov.). The new genus Levispongia gen. nov. belongs to the family Corallistidae. The new species Levispongia meyeri gen. nov. sp. nov. has dicranoclone desmas, complex dichotrianes with strongly spinose upper surfaces of the cladome and microstyles as the only microscleres. Phylogenetic relationships of these new species are discussed and compared with other material from the Caribbean and Central to the West Pacific Ocean. urn:lsid:zoobank.org:pub:844E385C-9A92-4F1B-B85C-9C1E319CD13F
Highlights
Submarine caves share several ecological features which often resemble that of deep-sea habitats includ ing darkness, hydrodynamic, geochemical and faunal compositions (Harmelin & Vacelet 1997)
The observed morpholo gical features from all these various cave lithistids show high affinities to those of the Mesozoic of Europe (Łukowiak et al 2014; Frisone et al 2016; Świerczewska-Gładysz 2016), which would suggest that most of these species represent a relict fauna with probable Tethys origin as already predicted for other non-cave lithistids (Reid 1967; Manconi 2011) and recently tested with molecular clocks for the lithis tid genus Vetulina Schmidt, 1879 (Sphaerocladina Schrammen 1924) (Schuster et al 2018). In this integrative taxonomy study, we describe for the first time four new lithistid demosponges and one new genus from two shallow submarine caves in French Polynesia: Ekamako Cave at the southern coast of Nuku Hiva (Marquesas Islands) and Te Pari Cave on Tahiti Iti peninsula (Tahiti island, Windward Islands, Society Islands) (Figure 1)
We report for the first time the occurrence of lithistids in French Polynesia and subsequently increase the current knowledge on Pacific lithistids
Summary
Submarine caves share several ecological features which often resemble that of deep-sea habitats includ ing darkness, hydrodynamic, geochemical and faunal compositions (Harmelin & Vacelet 1997). Temperature and habitat sizes exist (Moldovan et al 2019), these submarine caves are often colonized by deep-sea invertebrates like gas tropods, annelids, crustaceans and sponges (Bussotti et al 2006; Gerovasileiou et al 2015; Culver & Pipan 2019). Since most of these caves are accessible by SCUBA diving, they provide a unique opportunity to study various aspects of deep-sea sponge biology and systematics (Vacelet 1996). Sponge cave biodiversity has been well studied in the Mediterranean Sea The Mediterranean submarine caves are all of karstic origin (limestones) and are a large biodiversity reser voir of sponge species that are otherwise only recorded
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