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

SUMMARY : S everal lithistid sponges are described from Mediterranean caves occurring in the northwestern and Adriatic basins. In the Corallistidae, Neoschrammeniella bowerbanki and Neophrissospongia nolitangere are recorded for the first time from the Mediterranean, whereas Neophrissospongia radjae n. sp. and Neophrissospongia endoumensis n. sp. are described as new. In the Theonellidae, the common sponge previously identified as Discodermia polydiscus is described as Discodermia polymorpha n. sp. Fossil specimens from the 3PP cave are tentatively attributed to Neoschrammeniella bower- banki . The distribution and affinities of this lithistid fauna are discussed. la esponja común, que hasta la fecha se había identificado como Discodermia polydiscus se describe como Discodermia polymorpha n. sp. Ejemplares fósiles de la cueva de los 3PP se asignan provisionalmente a Neoschrammeniella bowerbanki . Se discute la distribución y afinidades de la fauna de las lithistidas. Palabras clave : Porifera, lithistidas, nuevas especies, Mediterráneo, cuevas submarinas, afinidades biogeográficas, esponjas fósiles.

In this paper we examine the lithistids collected over years in several caves from the western Mediterranean, along the French coast near Marseille and on the Spanish coast of the Medes Islands, and in several caves along the Dalmatian coast of Croatia in the Adriatic.

MATERIALS AND METHODS
Most of the studied sponges were collected over several years of investigations from the submarine caves in the western Mediterranean (Fig. 1).Specimens of Discodermia from the Dalmatian caves (Fig. 1) were collected and donated for research by Dr. Tatjana Bakran-Petricioli (University of Zagreb, Croatia), and one specimen of Neophrissospongia was collected by Mr Tonci Radja (Speleological Society "Spiljar", Croatia).
Cave no 5, Dalmatian cave (Croatia), Korkula Island (42°57'16.26"N,17°07'52.21"Efor the town of For the study of spicules, the sponge tissue was digested in hot HNO 3 , then acid was removed by washing several times with distilled water and finally with propanol.A suspension of loose spicules was dropped on the stub surface, dried and covered with platinum or gold-palladium for observations under a Phillips XL 20 (Warszawa) and a Hitachi S570 (Marseille) scanning electron microscopes.Histological preparations including both living tissue and skeleton were made by embedding in epoxy resin © Araldite sponge fragments stained with acid fuchsin.The inclusions were then cut with a low-speed saw using a diamond wafering blade.The sections were wet-ground on abrasive discs, and later mounted on glass slides for transmitted light observations.
Remarks.So far this genus was known only from the SW Pacific region, and this is the first report outside that region.However, the species Corallistes bowerbanki (here attributed to Neoschrammeniella) was earlier known from the Atlantic (see Sollas, 1888).(Johnson, 1863) (Figs.2K-L, 4-5, Table 1) Johnson, 1863: 257;Bowerbank, 1869: 94, Pl. 6, Figs. 5-8. Corallistes bowerbanki;Carter, 1876: 460;Sollas, 1888: 308.Corallistes masoni (Bowerbank, 1869); Pouliquen, 1969a: 42, Pl. 8, Fig. 2;Pouliquen, 1969bPouliquen, : 1325;;Pouliquen, 1972:  Diagnosis.Cup-shaped to contorted lamellate masses with thick walls; ectosomal dichotriaenes smooth; choanosomal desmas with high irregular tubercles which may be sculptured with low tubercles; microscleres are two types of spirasters: one with short and thick arms, the second with long thin and pointed arms.Description.Relatively large massive sponges, 8 x 6 x 6 cm, in shape of irregular cup to contorted lamellae 10-15 mm thick.Colour clear brown to cream in life and in alcohol.Surface smooth to the naked eye, but under the microscope one side (the internal one) with numerous thin oxeas protruding from the choanosome, giving a hairy appearance to its surface.The sponge was attached directly by the lower part to the hard substrate.

Neoschrammeniella bowerbanki
Ectosome with dichotriaenes and densely packed microscleres of spiraster type.Outer sponge surface smooth with densely packed ectosomal dichotriaenes visible on the surface.Inner surface hispid with numerous small bunches of tiny oxeas protruding from the choanosome.
Choanosomal desmas are dicranoclones forming net-like meshwork on both sides, with oval to angular meshes.Dicranoclones are approximately 290-402 µm in size.They are rather irregular, highly arched and covered with numerous high and irregular tubercles which are in turn divided into several smaller irregular lobes/tubercles.
Microscleres are two types of spirasters; type I has short and thick rays with numerous massive, often bifid spines, and measures 17-24 µm x 7.06 -11.1 µm; type II has long thin and pointed arms which are sparsely covered with tiny spines, and measures 26.2-39.2x 18.5-23.9µm.

Remarks.
No formal diagnosis was ever given for N. bowerbanki, so we present it here.This species was originally attributed by Johnson (1863) and Bowerbank (1869) to the genus Dactylocalyx (hexactinellid sponge), and by Sollas (1888) to the genus Corallistes Schmidt, 1879.Based on skeletal characters we decided to transfer it to the genus Neoschrammeniella Pisera and Lévi, 2002a.The main difference between Corallistes and Neoschrammeniella is in the microscleres: Corallistes has two types of massive spirasters with pointed arms, while Neoschrammeniella has two types of long spirasters, one with pointed and one with blunt arms (Pisera and Lévi, 2002a).
N. bowerbanki has usually been reported from the Mediterranean under the name C. masoni (Bowerbank).We consider this determination clearly erroneous based on comparison of the studied cave material and the examination of type material of both C. bowerbanki (Figs 3C,(6)(7) and C. masoni (Figs 8-9).We illustrate here, for comparison, for the first time in SEM, spiculation of the holotypes of these two species.The investigated Mediterranean material is thick walled while the type of C. masoni has much thinner walls; C. masoni has only one type of long spirasters with long and thin arms, while the type of C. bowerbanki and our specimens have two types of spirasters of different morphology (see description).This difference in microscleres was already observed by Carter (1873).Based on these observations the identity of the described specimens from Mediterranean caves with the species C. bowerbanki, and not with C. masoni, is beyond any doubt.Topsent (1892) described and illustrated under the name C. bowerbanki a species which has dichotriaenes with tuberculated cladome, similar to that in Neophrissospongia nolitangere, as well as abundant "linear" microxeas, which are most probably spinose microstyles recognized also in that species.
Occurrence. 3PP cave (this study), Figuier and Cap Morgiou caves (Pouliquen, 1972).In the 3PP cave, the sponge was attached to vertical walls, approximately 85 m from cave opening, 20-22 m depth, in a water mass with a nearly constant temperature, ca 13 to 15°C.
Distribution.Eastern Atlantic Ocean, Mediterranean Sea.
Genus Neophrissospongia Pisera and Lévi, 2002a Type species.Corallistes nolitangere Schmidt, 1870 Emended diagnosis (after Pisera and Lévi, 2002a).Irregular cup-shaped to contorted lamellate masses, ear-shaped or massive clavate growth forms.Ectosomal spicules are dichotriaenes bearing on the upper cladome surface strong spines and/or tubercles; choanosomal desmas are dicranoclones; microscleres are massive streptasters/amphiasters and spinose microtylostyles.Remarks.In the diagnosis of this genus Pisera and Lévi (2002a) omitted the presence of microtylostyles among microscleres.A re-examination of the type material revealed that they are rare but present.This fact, as well as the discovery of new forms with different morphology, is the reason for emending the genus diagnosis.
Description.Ear-shaped when young, to irregular cup-shaped when larger, with walls about 1.7 cm thick, and attached to the hard substrate with entire lower part.Colour clear brown in life and in alcohol.Outer inhalant surface with numerous densely distributed ostia, 30-40 µm in size.Inner surface smooth except for several oscular openings located on small elevations about 1-2 mm across.Ectosome on both sides densely packed with dichotriaenes and thick crust of massive astrose microscleres (Fig. 12).Below the tangential rays of dichotriaenes there are large subdermal cavities with surface covered with microstyles; in the choanosome those microstyles are radially arranged (Fig. 12B).Choanocyte chambers rarely visible in our material.Abundant, large granular cells, 30 µm in diameter with a 5 µm diameter nucleus in the choanosome.
Choanosomal skeleton made of massive and strongly tuberculated rather linear dicranoclones, forming irregular net-like structure with irregular net openings up to 0.5-0.6 mm wide.Skeletal net denser on the exhalant surface.Sinuous, radially arranged canals occur at the surface of the choanosomal skeleton, on the oscular side, leading to oscules.Dicranoclone desmas, approx- imately 289-382 µm in size, very massive and densely covered with high, more or less mushroom-shaped tubercles which may divide into smaller low elevations.
The desmas are very tightly articulated.
Ectosomal dichotriaenes with rhabdome 313-800 x 15-30 µm, sometimes slightly curved or flexuous, generally with a blunt point, and cladome 160-313 µm in diameter.The cladome, which bears numerous loosely spaced irregular pointed tubercles, may show in addition irregular branches which cause a slight resemblance to phyllotriaenes.However, axial canals extend to all the cladome rays, clearly pointing to their dichotriaene, and not phyllotriaene (where axial canals are very short and limited to the centre of cladome only) nature.
Microscleres of two types.The first type are spirasters/streptasters with thick arms covered with numerous massive pointed spines, which occur mostly from the half-length to their tips; they are 8.4-15.4µm long and 6.1-12.9µm large.The second type are spinose microtylostyles, with narrow and elongated heads which are also spinose, with spines along the spicules directed toward the head and rather sparsely distributed; they are 74-137 long x 1.4-2.1 µm large.
Remarks.The examination of the specimen used by Chombard (1998, see also Chombard et al., 1998) in her molecular studies and determined as C. masoni (Bowerbank, 1869) revealed that it is in fact Neophrissospongia nolitangere.The specimens of this species are usually ear-to irregular cup-shaped, but a recently collected specimen from the Azores (personal information from Joana Xavier, specimen ZMA POR 19967) attains a very large size (about 1 m in diameter and 40-50 cm in height) and forms folded lamellate masses.
Etymology.From Endoume, the type locality, a few metres from the Marine Laboratory in Marseille, France.Diagnosis.Cup-shaped Neophrissospongia with oscular openings on the upper side.Ectosomal dichotriaenes with very massive, thick and irregular, tuberculated cladome.Choanosomal dicranoclones very massive with a central core, strongly tuberculate; arms bearing ring like sculpture.Two types of microscleres: massive spirasters/streptasters with short, thick spines, and slightly spinose microtylostyles.
Description.Small, cup-shaped sponge with thick walls, 25 x 20 mm large and 15 mm high, slightly oval in cross section.Walls about 6 mm in thickness, with rounded edges.The single studied specimen was attached to a subhorizontal rocky substrate by its entire base.Upper concave surface bearing several oscular openings, about 0.7 mm wide located on small elevations 1-2 mm in diameter.Outer inhalant surface with numerous round ostia 23-54 µm in diameter and with a dense crust of microscleres (spirasters/streptasters). Below the outer surface large subdermal cavities lined with numerous microtylostyle microscleres.
Ectosomal dichotriaenes with massive cladomes (248-283 µm in diameter), irregular at first sight and thus resembling phyllotriaenes, but with the axial canals extending along all main branches up to their tips.This irregularity of the cladome follows from the fact that the main branches further ramify, producing irregular, densely packed side branches with spine-like tips.Upper surface of the cladome covered with numerous densely packed, vertically pointed, spine-like tubercles.Rhabdome rather thick, sometimes slightly flexuous, often with a few swellings, with a blunt or round end: 320-615 x 32-45 µm.
Choanosomal skeleton made of strongly tuberculated, massive dicranoclones approximately 318-490 µm in size.Desmas very tightly articulated and forming irregular meshes.Dicranoclones with a central massive core from which 3-5 arms extend downwards.They are very densely covered with complex low tubercles, round in the centre of the desma but heavily ornamented with smaller and low rounded tubercles.On the arms of dicranoclones the main tubercles may join, forming ring like structures, also ornate with smaller rounded tubercles.Microscleres of two types.Type I a massive spiraster/streptaster, 12.7-20.1 x 11.4-16.6µm, with short and thick arms covered with triangular low spines, occurring in the ectosome.Type II a spinose microtylostyle, 68.8-123 x 1.6-1.7 µm with the head only slightly marked, occurring in subdermal cavities and in the choanosome.
Remarks.This species differs from the most morphologically similar N. nolitangere in details of spiculation.In N. endoumensis n. sp.dichotriaenes are much more massive and have more irregular cladomes with numerous branches with densely distributed spines, and form a dense, canopy-like surface, while in N. nolitangere clades are less branched and stay separate, having also less densely distributed ornamentation.In N. endoumensis the rhabdomes of dichotriaenes are conical, blunter and thicker.Also spirasters/ streptasters are different, i.e. more regular and massive in N. endoumensis, and have shorter, massive arms that are rounded at their tips.The dicranoclone desmas are more massive and with a central part swollen in N. endoumensis, while in N. nolitangere they are rather linear.The choanosomal skeleton of N. nolitangere displays a regular net with large meshes in the inhalant surface not observed in N. endoumensis.
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.The microscleres of N. endoumenis have larger size on average and spirasters/amphiasters are massive, more regular and with shorter rounded arms.
From N. radjae n. sp., which is club-shaped with one narrow spongocoel located at the top of the sponge, N. endoumensis differs in being cup-shaped, and in some details of spiculation (see descriptions and remarks to N. radjae below).
Occurrence.Endoume cave, attached to a subhorizontal rocky surface, 5 m depth, under dim light condition approximately 5 m from cave opening.Neophrissospongia radjae n. sp.
Etymology.From the name of the diver, Tonci Radja who had collected this species.
Description.Small clavate sponge about 45 mm high and 30 mm in diameter, clear brown in alcohol.It is polygonal in cross section, resulting from the presence of flattened to slightly concave areas, separated by low rounded and wide ridges, on lateral surfaces of the sponge.The concave areas, being inhalant, are finely porous.The sponge summit is concave with two closely located oscular openings which are about 1.5 mm wide.The attachment base is about 19 mm wide.
In a preparation there is a thick layer of microscleres in the ectosome.Ectosomal dichotriaenes simple (without additional branching except at their tips) and regular, bearing on the upper surface of the cladome massive tubercles usually divided into smaller tubercles or thick pointed spines.Rhabdome 220-639 x 20-30 µm, with a blunt or acerate end.Cladome 160-340 µm in diameter.
Choanosomal desmas typical dicranoclones, 280-500 µm in diameter, forming an irregular net-like structure, with rather sparsely distributed round tubercles which may be ornate with smaller secondary tubercles.
Remarks.Although rather similar in spicular characters to N. nolitangere, the new species, which is a massive, club-like sponge with a centrally located osculum, differs completely in morphology from N. nolitangere, which is an ear-shaped or shallow cup-shaped sponge when young and may form large folded masses when old (Joana Xavier, Amsterdam, pers.info.).The two species differ also in details of desmas and microscleres: spirasters are much more massive in N. radjae than in N. nolitangere, as are the cladomes of dichotriaenes, which are also more regularly built in the new species.
This species differs from N. endoumensis n. sp. in the clavate habitus.In N. endoumensis the rhabdome of dichotriaenes is more blunt and thicker, while the cladome is more massive and very densely covered with spines that are rather triangular in N. endoumensis and massive-irregular in N. radjae n. sp.Spirasters also differ slightly, being less regular and with longer arms than in N. endoumensis.Desmas of N. radjae are less thick (massive) and more linear than in N. endoumensis, where they are much thicker (massive) with a central swollen part, and are more densely covered with thicker and more complex tubercles.
Etymology.From Latin polymorpha -multishaped, referring to high variability of morphology and spicules of the species.
Diagnosis.Small polymorphic Discodermia, varying in shape from nearly spherical to irregular masses with protuberances.Oscula grouped in poorly defined fields or individually dispersed.Ectosomal discotriaenes very variable, from perfectly circular and concave to oval with irregular outline.Choanosomal desmas smooth tetraclones.Microscleres spinose microxeas and microrhabds.
Description.Polymorphic sponges more or less spherical (especially when young), attached to the substrate by a short pedicel or by their entire surface, growing to irregular masses with short protuberances, up to 57 mm in diameter.Surface smooth, entirely covered with ectosomal discotriaenes.Oscula up to 100 µm in diameter, dispersed or in irregular fields.
Ectosomal discotriaenes with a short rhabd (60-65 µm long) and a slightly concave disc, varying in shape from perfectly circular in some specimens to circular with irregular margins, and to completely irregular.Ectosomal discotriaenes are very tightly packed, often strongly overlapping, except in the specimen from the Aegean Sea, where they are loosely packed, usually not touching each other and the areas between them are infilled with a thick crust of microscleres.Discotriaene diameter strongly variable, from 174 to 366 µm, between various areas of the same sponge, as well as between various specimens from the same cave and/ or various caves.However, no consistent pattern of this variability has been observed (see Table 2 and Fig. 19A, C, E, G, Fig. 20A, C, E, G, and Fig. 21 for details).
Choanosomal desmas smooth, rather irregular tetraclones with poorly branched tips by which they articulate with each other, 370-718 µm in diameter (Table 2).Choanosomal skeleton rather irregular, differing strongly in regularity and degree of desma articulation (see Fig. 19B,D,F,H,Fig. 20 B,D,F,H), between various caves and even between specimens from the same cave.Particular tetraclones differ also in size and thickness of the clones, without any consistent trend allowing for differentiation of the various populations (except perhaps Dalmatian specimens).Canal openings in the choanosomal skeleton irregular and only slightly larger than normal skeletal meshes.
Remarks.The genus Discodermia is a difficult one because it has few and very variable characters useful for species differentiation.The studied material from various submarine Mediterranean caves is a good example of the problems encountered in the taxonomy of this genus.The shape of the various specimens is variable, as are the spicules, and molecular data are highly desirable to solve the problem of the species diversity of the genus in the Mediterranean.
We have decided to attribute all our specimens to one morphospecies, assuming that there is only one highly polymorphic species occurring in all the caves and in the bathyal zone.However, the possibility that different species could be distinguished in different areas of the Mediterranean cannot be excluded and should be tested by using molecular markers.Preliminary data obtained by Pierre Chevaldonné (pers.comm.) with mt COI and rDNA ITS-2 indicate no differences between specimens from the Medes Islands and several caves of the Marseille area.However, specimens from Croatia (Dugi Otok) display significant differences (indels) in their ITS sequences compared with those from the Medes and Marseille, a difference that is at present difficult to evaluate, particularly in the absence of sequences from D. polydiscus or D. ramifera.
The specimens that we attribute to this new species are very variable both in morphology (although sub-spherical forms are dominant) and in spicule characters.Our inability to find any discrete group or pattern in this variability justifies the present interpretation as a single, variable species.This polymorphism could be related to differences in cave environments, i.e. temperature, local silicic acid concentration, and nutrient levels, between particular caves or between the various cave parts.This problem can be studied in detail only with systematic collection of sponge specimens and study of local environmental parameters, which were not possible for this study.
Although polymorphic, these Mediterranean Discodermia specimens significantly differ from the two most closely related Atlantic species, D. polydiscus Bowerbank, 1869, to which the Mediterranean Discodermia have been previously attributed (Pouliquen, 1969a(Pouliquen, , b, 1972;;Vacelet, 1969), and D. ramifera Topsent, 1892, and we propose to consider them as belonging to a new species.Discodermia polymorpha n. sp. is mostly spherical to irregular in shape, whereas D. ramifera is ramose and D. polydiscus is cup-shaped to irregular, with oscules located on eleva-tions, which is not observed in the new species.Both the Atlantic species have a larger size.The desmas of D. polydiscus and D. ramifera are smaller on average, more massive and with strongly branched/tuberculated zygomes, and form a denser skeleton than those of D. polymorpha n. sp., which are relatively thin and poorly branched at zygomes.Discotriaenes, which are similar in size in the two species, are more variable in shape and often slightly incised in D. polymorpha, while they are oval to round in D. polydiscus.The same is true of microscleres: they are more variable in the new species than in D. polydiscus.Acanthorhabds are usually cylindrical and curved, only rarely massive to fusiform, and slightly longer in D. polymorpha, while they are as a rule massive cylindrical in D. polydiscus.Acanthoxeas are also rather cylindrical and never fusiform, usually thinner and slightly longer in D. polymorpha than in D. polydiscus.The specimen from the bathyal zone of the Aegean Sea fits the variability observed in cave specimens, and we consider it as belonging to the new species from shallow water caves.Occurrence and ecology.Very common in numerous caves from the western Mediterranean and the Adriatic (Medes Islands, Marseille area, Croatia), from 3 to ca. 20 m in dark zones, also recorded from the bathyal zone (210-360 m) in the Aegean Sea.In some caves, its abundance has been estimated to be 10 individuals/m² on walls or ceilings at 3 m depth (Pouliquen, 1972).

Affinities of the studied lithistid sponges
Because of the Messinian Event, most of the Recent fauna of the Mediterranean must be either immigrants from the Atlantic, relicts from the Pre-Messinian time (see Rögl and Steininger, 1984;Por, 1989, for a review), or recent endemics evolved in the Mediterranean Sea since the establishment of normal marine condi-tions in the Pliocene.In the case of studied lithistids we have in our material examples of the Atlantic species (Neophrissospongia nolitangere, Neoschrammeniella bowerbanki), and of new endemic species (Neophrissospongia radjae, Neophrissospongia endoumensis, Discodermia polymorpha) related to well-known Atlantic species.This is the first record in the Mediterranean of N. nolitangere, a species that is known from the eastern Atlantic (including the Azores) (Lendenfeld, 1903;Topsent, 1904).The other corallistid reported in this paper, Neoschrammeniella bowerbanki, is recorded for the first time from the Mediterranean, but in fact it was earlier described in that sea by various authors under the name Corallistes masoni (see Pouliquen, 1969aPouliquen, , b, 1972;;Magnino et al., 1999).The dead specimen studied by Magnino et al. (1999) has no microscleres

Fossilized lithistids
In addition to the living material, several specimens of fossilized lithistid sponges were collected from the 3PP cave (deposited as MNHN-DJV-126 un-  der the name Neoschrammeniella cf.bowerbank, Fig. 24).They are usually conical, cup-shaped sponges and are up to 7 cm high and 8 cm in diameter at the top, with a wall up to 15 mm thick.The sponge body is substituted with calcium carbonate in the form of pelloids and has numerous desmas preserved.In the fossil record such types of sponge preservation by calcium carbonate are very common and they are often called "mummies" (Matyja, 1978;Pisera, 1997).
Similar fossilized sponges occur in some Sardinian caves (personal observation) and in the deep Mediterranean Sea (Allouc, 1987).In the latter case they were interpreted by Allouc (1987) as relicts originating during Pleistocene cooling.In our case they are probably more recent and dating from the previous immersion of the 3PP cave dating approximately 8000 y, or from a warm episode during interglacial periods.Dating needs further verification by isotopic methods and is beyond the scope of the present paper.The problem is even more interesting because we are aware of the occurrence of similarly preserved lithistid forms in submarine caves from Sardinia.We isolated the desmas from these fossilized lithistids by dissolving a fragment of the sponge in acetic acid (Fig. 24).At first sight the desmas resemble rhizoclones but they are larger and in some case are ornate with tubercles rather than spines, which is typical for rhizoclones.They also have an internal core of cloudy silica, which is typical for dicranoclone desmas rather than rhizoclones, and display traces of surface corrosion.Accepting their rhizoclone nature suggests that there could have been another lithistid, a rhizomorine resembling Leiodermatium, inhabiting the cave in some past.This cannot be rejected as the genus Leiodermatium was reported from the Mediterranean (Magnino et al., 1999).However, the desmas from the fossilized lithistids could also be corroded dicranoclones (during calcium carbonate deposition in the process of "mummification" pH values must be rather high, thus allowing for rapid corrosion of opaline spicules).If they are corroded dicranoclones, they may belong to one of the corallistids still living in the cave.In order to identify more clearly their nature, we have treated desmas of living Neoschrammeniella bowerbanki, which have similar morphology, with diluted HF acid for 5, 15 and 30 minutes.The corallistid desmas treated for 30 minutes produced corroded spicules identical to those obtained from fossilized sponges.It thus appears that the fossilized lithistids from the 3PP cave are not rhizomorine lithistids, but belong rather to one of the Corallistidae species still extant in the cave, most probably N. bowerbanki judging from shape, size, wall thickness and desmas general shape and size.The age and mechanisms of origin of these fossilized cave lithistids in the Mediterranean should be studied in more detail in the future, especially as they may provide interesting insights on the fossilization processes of lithistid sponges.

Fig. 13 .
Fig. 13.-Neophrissospongia endoumensis n. sp.holotype MNHN-DJV-120.A, Details of ectosome of the outer inhalant surface, with a dense crust of spiraster microscleres; B, Transverse section of the ectosomal region (inhalant surface at the top), showing large subdermal cavities with numerous microtylostyles; C, Surface view of the choanosomal skeleton, with several young desmas; D, Details of the choanosomal skeleton of dicranoclones; E, Young dicranoclone articulating to older desmas; F, Details of dicranoclone articulation and ornamentation.

Table 2 .
-Spicule size (µm) of Discodermia polymorpha n. sp.specimens from various caves and from single caves.