Rare sponges from marine caves: discovery of Neophrissospongia nana nov. sp. (Demospongiae, Corallistidae) from Sardinia with an annotated checklist of Mediterranean lithistids

Abstract

A new record of lithistid demosponges is reported from a western Sardinian karstic cave. Th e new specimen matches the trait of the genus Neophrissospongia (Corallistidae) for an ectosomal skeleton of radial dichotriaenes, a choanosomal skeleton as a network of dicranoclone desmas, and streptaster/amphiaster microscleres with short spiny rays bearing blunt tips. Th e cave-dwelling N. nana nov. sp. diverges from the other species of the genus in diagnostic characters such as the large irregular plate-like growth form, the topographic distribution of inhalant and exhalant apertures, and a smaller size of all spicular types. Moreover it displays an additional rare second type of dichotriaenes with smooth cladomes, shared with other genera of Corallistidae but never reported before for the genus Neophrissospongia. In addition N. nana nov. sp. bears stylelike sub-ectosomal spicules shared with N. microstylifer from deep water of New Caledonia. As for the latter trait, a present in-depth analysis of N. nolitangere from the Atlantic Ocean contrasts with previous historical records reporting monaxial spicules as oxeas/anisoxeas. Th e diagnosis of the genus Neophrissospongia is therefore emended for the growth form and for the micro-traits of dichotriaenes and monaxial sub-ectosomal spicules. Morphological data indicate that the new species is allied to N. nolitangere and N. microstylifer from Eastern Atlantic and New Caledonian deep water, respectively, and its record confi rms the highly disjunct geographic range of the genus Neophrissospongia in the Lusitanian-Macaronesian-Mediterranean area and the western Pacifi c Ocean supporting the relic condition of the genus in the Mediterranean Sea. Th is discovery stresses the key status of Mediterranean palaeoendemics as possible remnants of an ancient Tethyan fauna and focuses the need to plan conservation measures for these rare cave-dwelling sponges.

Marine Caves of the Mediterranean Sea: A Sponge Biodiversity Reservoir within a Biodiversity Hotspot

“…The presence of P. massiliana in distant karstic areas matches a biogeographic model of disjunct distribution with metapopulations isolated in cryptic habitats of the western and central Mediterranean Sea, while fossils of this species have been found in Apulia (Italy) and the Island of Crete [106]. Moreover, during the last decade, several new species of the order Lithistida have been reported from shallow water caves, including possible i) relictual species or palaeoendemics [29], [107], and ii) remnants of the subtropical/tropical assemblages, which thrived in the Mediterranean during warm periods of its history and survived only in the warmer southeastern basin during the subsequent cooling episodes [28].…”

Lithistid sponges from submarine caves in the Mediterranean: taxonomy and affinities

“…This species differs from the encrusting N. nana Manconi and Serusi (2008) in being cup- shaped and in having massive, strongly tuberculated desmas, while N. nana has slender desmas, with tubercles bearing smooth heads, which form a loose network. Also, the ectosomal dichotriaenes in N. endoumensis are more massive, with a much more branched tuberculated cladome than in N. nana.…”

“…One of the particularities of these caves is a common occurrence of lithistid sponges. Lithistid sponges are rare in the Mediterranean Sea and only 9 species of 9 genera have been reported so far (see detailed review in Manconi et al, 2006;Manconi and Serusi, 2008, and references herein). Those cited from submarine caves are even less common and are poorly studied.…”

Revision of the genus Exsuperantia Özdikmen, 2009 (Tetractinellida: Phymaraphiniidae) with description of a new species from the Atlantic Ocean

“…Schmidt 1870Schmidt , 1880Topsent 1898;Lévi & Lévi 1983, 1988Pomponi et al 2001;Kelly 2007). Nevertheless, they can also be found in shallow waters, and in caves and reef tunnels (Vacelet & Vasseur 1965;Manconi et al 2006;Manconi & Serusi 2008;Pisera & Vacelet 2011).…”