Two new lithistids (Porifera: Demospongiae) from a shallow eastern Mediterranean cave (Lebanon)

Abstract

Two new species of lithistid sponges, Gastrophanella phoeniciensis sp. nov. (Siphonidiidae) and Microscleroderma lamina sp. nov. (Scleritodermidae) are described from a submarine cave, depth 2^3 m, in Lebanon. They are the ¢rst Mediterranean records of two genera with a mainly tropical distribution, Gastrophanella being known from the western Atlantic (Caribbean, Brazil), central eastern Paci¢c (Mexico) and South Africa, and Microscleroderma from the Indo-Paci¢c and the eastern Atlantic (Senegal). They are interpreted as remnants of a warmer period in the Mediterranean that survived the subsequent cooling only in the warmer eastern basin. Gastrophanella phoeniciensis sp. nov. is closely related to G. cavernicola from Brazil and Belize, from which it di¡ers essentially in its shape. Microscleroderma lamina sp. nov. is characterized by a lamellar shape, short oxeas and having hair-like oxeas arranged around the aquiferous openings.

Demosponge distribution in the eastern Mediterranean: a NW–SE gradient

“…The preference of keratose sponges for shallow and warm habitats has been attributed to the inhibition of their larval dispersal and settlement success by the decrease in temperature (Maldonado and Young 1996). Out of the 56 genera recorded in the Levantine (Table 5), two (Gastrophanella and Microscleroderma) have a tropical distribution (Perez et al 2004), while at least 32 (e.g., Agelas, Alectona Chelonaplysilla, Chondrilla, Chondrosia, Didiscus, Erylus, Spongia) have a distinct tropicalsubtropical diversity center, lacking or rare in cold water areas (estimated according to van Soest 1994). …”

“…The above authors claim that the general pattern of biotic affinity is determined predominantly by horizontal (geographic) distances while the role of vertical distance (bathymetry) is much less significant. Table 5 List of demosponge species reported from the Levantine Sea (sources : Burton 1936;Levi 1957;Tsurnamal 1967Tsurnamal , 1969aTsurnamal , 1969bIlan et al 1994;Muricky et al 1998;Carteron 2002;Perez et al 2004 (Vacelet, 1959) 0 0 4 1 1 2 2-110 AM Number of specimens per species in each area were transformed into semiquantitative values as follows: 0 absent species, 1 species recorded once in an area, 2 species recorded with 2-5 specimens, 3 species recorded with 6-10 specimens, 4 species recorded with 11-20 specimens and 5 species recorded with more than 20 specimens. Depth is presented in m (* = species found in caves).…”

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

“…Those cited from submarine caves are even less common and are poorly studied. Only six lithistid species of six genera were reported from submarine caves: these are Discodermia polydiscus (Bowerbank, 1869) (Theonellidae Lendenfeld, 1903) and Corallistes masoni (Bowerbank, 1869) (Corallistidae Sollas, 1888) from the caves around Marseille (Pouliquen, 1969a(Pouliquen, , b, 1972, Gastrophanella phoeniciensis Perez, Vacelet, Bitar andZibrowius, 2004 (Siphonidiidae Lendenfeld, 1903) and Microscleroderma lamina Perez, Vacelet, Bitar andZibrowius, 2004 (Scleritodermidae Sollas, 1888) from a Lebanese cave (Perez et al, 2004), Aciculites mediterranea Pisera, 2006 (Scleritodermidae Sollas, 1888) from a northern Sardinian cave (Manconi et al, 2006), and Neophrissospongia nana Serusi, 2008 (Corallistidae Sollas, 1888) from a western Sardinian cave. The species Discodermia polydiscus and Coral-listes masoni were also recorded from the deep sea in the bathyal zone (Vacelet, 1969;Magnino et al, 1999, respectively).…”

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

“…Nine species belonging to 9 genera of 6 families have been until now recorded in the Mediterranean Sea (Appendix 1) (Topsent 1892a(Topsent , 1893(Topsent , 1925Vacelet 1960Vacelet , 1969Pouliquen 1969Pouliquen , 1972Pulitzer-Finali 1970Pansini 1992Pansini , 1995Boury-Esnault et al 1994;Magnino et al 1999;Pansini and Longo, 2003;Perez et al 2004;Longo et al 2005;Manconi et al 2006;Zibrowius and Taviani 2005). Th e taxonomic richness appears to be notably higher in the tropics (Lévi 1991;Pisera and Lévi 2002;Schlacher-Hoenlinger et al 2005) whereas the low values in the Mediterranean may be explained by the occurrence of extinction phenomena due to harsh environmental/climatic changes during the history of this basin (e.g.…”

“…All Mediterranean records refer to genera characterised by a highly disjunct distribution with a spot-like pattern in tropical/subtropical latitudinal ranges of the Atlantic, Indian and western Pacifi c oceans. Th ese taxonomic and biogeographic patterns suggest the condition of lithistids as remnants of an ancient Tethyan fauna (Reid 1967;Perez et al 2004;Manconi et al 2006;Pisera and Vacelet 2006).…”