Growth form encrusting, thin (3–6 mm), in irregular patches of up to 20 cm in diameter. Surface evidently conulose (1–3 mm) because of the dense dendritic “forest” of “small horny trees” forming the typical skeleton of all Aplysilla species. Oscules (1–3 mm) scattered and not evident; inhalant apertures rarely visible in vivo. Colour from rose to yellow. Skeleton of large ramified fibres arising from a spongin basal plate strictly adhering to the substratum. Dendritic fibres with maximum size of ca. 5 mm in length, ca. 300 µm in diameter at the basal portion, and no more than 50 µm in diameter at terminal branches (up to 4–6 sometimes anastomosing). Spongin layered, transparent, pale in colour, not cored with mineral debris.

Cave, rocky/detritic/muddy bottom, hyperhaline canal (Manfredonia), artificial reef, coralligenous community, and epibiotic on red coral and on Pinna nobilis (L., 1758). Bathymetric range 1–110 m.

Blava, Calamars, La Catedral, J1 caves (Balearic Sea); Galatea Cave* (Sardinian Sea); Béar, Troc, Endoume, Figuier, Trèmies, Niolon caves (Gulf of Lions); Western-Zoagli Cave (Ligurian Sea); Mago, Gaiola, Secca delle Formiche-Vivara, Mitigliano caves (Central Tyrrhenian Sea); Azzurra Cave (Southern Tyrrhenian Sea); Taccio Vecchio 1 Cave-Lampedusa*, Zembra caves (Sicily Channel); La Regina Cave (Southern Adriatic Sea); Trypia Spilia, Ftelio, Madhes, Andros caves (Aegean Sea) (Vacelet 1959; Sarà 1961a 1964a; Labate 1965; Boury-Esnault 1971; Pouliquen 1972; Pulitzer-Finali and Pronzato 1976, 1980; Pansini et al. 1977; Pulitzer-Finali 1977; Pansini and Pronzato 1982; Balduzzi et al. 1989; Bibiloni et al. 1989; Benedetti-Cecchi et al. 1998; Ben Mustapha et al. 2003; Pronzato and Manconi 2011; Cadeddu 2012; Gerovasileiou and Voultsiadou 2012).

Growth form encrusting (less than 2 mm in height). Surface conulose, ornamented by a network of rounded meshes (200–300 µm in diameter) loaded of inclusions; inside the meshes surface is smooth and perforated by small apertures (15–40 µm in diameter). Colour from grey to violet (Vacelet 1959, 1969). Dendritic modules (tree-shaped) of the skeleton with fibres apically branched (80 µm in diameter at their base, 20 µm at the apical branch level).

Cave, coralligenous community, rocky bottom. On small pebbles or epibiotic on Microcosmus vulgaris Heller, 1877, Corallium rubrum (L., 1759) and Sarcotragus foetidus. Bathymetric range 1–150 m.

Blava, Calamars, Misidacis caves (Balearic Sea); Endoume, Figuier, Trèmies caves (Gulf of Lions) (Pouliquen 1972; Uriz et al. 1992; Martì et al. 2004; Pronzato and Manconi 2011).

Growth form encrusting. Surface conulose bearing a reticulate dermal membrane with fibre tips supporting conules. Colour in vivo “rouge carmin” as reported by the author, bright red. Dendritic skeleton arising from a basal spongin plate with the main fibres (up to 4 mm in height, 60–160 µm in diameter) evidently laminated and free of foreign material, with variably dense granular axial pith. Fibres. Horny spicules triactines free or connected to the main skeleton (rarely each to one another), with actins ca. 1.1–1.25 mm in length and 45–50 µm in diameter, gradually tapering towards the sharp tips. Rays linear, usually 3, rarely 2 or 4. Spicules sometimes with pith.

Cave, rocky bottom, coralligenous community. Bathymetric range 3–100 m.

Lerici Cave (Ligurian Sea); Secca delle Formiche-Vivara Cave (Central Tyrrhenian Sea); Taccio Vecchio 1 Cave-Lampedusa* (Sicily Channel) (Pulitzer-Finali and Pronzato 1976, 1980; Pronzato and Manconi 2011). Recorded as Darwinella australiensis.

Pronzato (1975) considered the Mediterranean species Darwinella simplex Topsent, 1892 as junior synonym of the Pacific species Darwinella australiensis Carter, 1885 (senior synonym) sharing diagnostic morphological traits as also focused by Topsent (1892). A re-evaluation of original descriptions vs. old and new materials allow us to consider Darwinella simplex Topsent, 1892 a valid species. The validity of Darwinella simplex solves the extremely disjunct Australian-Mediterranean geographic pattern and matches the hypothesis of a species complex.

Tubular habit with ten to fifteen slightly clavate hollow cylinders (up to 2 cm high, with a diameter of 5–8 mm) partly coalescing and arising from a common basal spongin plate (ca. 4.5 × 3 cm in diameter). Consistency soft and elastic, as the rule in all Spongionella species. Oscules apical (2–3 mm in diameter). Surface finely conulose with conules supported by tips of ascending fibres (conules ca. 100 µm high, 300 µm apart). Skeleton reticulate with a more or less regular network of generally quadrangular meshes (100–300 µm in diameter). Primary fibres (25–30 µm in diameter) connected by rare and irregular tracts (5–10 µm in diameter). Fibres laminated, clear, and uncored, with a transparent axis.

Cave, rocky bottom, epibiotic on Corallium rubrum. Bathymetric range 9–45 m.

Secca delle Formiche–Vivara Cave (Central Tyrrhenian Sea) (Pulitzer-Finali and Pronzato 1976, 1980; Pulitzer-Finali 1977; Pronzato and Manconi 2011).

The reticulate fibrous skeleton is atypical for Dendroceratida.

Growth form of Mediterranean specimens cushion-like, small (2 cm in diameter, 5–10 mm in thickness). Colour grey-greenish-brown. Consistency soft and elastic. Surface finely conulose with conules supported by tips of ascending fibres. Inhalant apertures not visible, oscules small (0.5–1 mm) and rare. Flagellate chambers large (70–80 µm) with small choanocytes. Skeleton network typical of the genus, extremely regular and practically indistinguishable from that of Spongionella gracilis. Fibres laminate, light and transparent, with axial pith lacking of inclusions that, when evident, shows a typical aplysillid structure. After Topsent (1929): primary fibres of a single dimensional class (25–35 µm); rare and irregular secondary connecting tracts (7–25 µm); meshes generally quadrangular 120–300 µm in diameter.

Cave, coralligenous community, Posidonia oceanica meadow, artificial reef, detritic bottom. Bathymetric range 4–380 m.

Meda Petita, Petita de la Vaca caves (Balearic Sea); Endoume, Figuier, Trèmies caves (Gulf of Lions); Farà Cave (Aegean Sea) (Pouliquen 1972; Bibiloni et al. 1984a; Pronzato and Manconi 2011; Gerovasileiou and Voultsiadou 2012).

The Mediterranean specimens ascribed to this species, are very different from the Atlantic ones.

Growth form usually irregularly massive (2–4 cm large, 1–2 cm thick) and commonly lobate. Specimens with large size (15–20 cm in diameter) and long digitations (5 cm) not infrequent. Colour constantly light rose-violet. Surface free of foreign debris, conulose with a regular fibrous network interconnecting apices of conules; conules large (3–6 mm high, 2–6 mm apart, sometimes clubbed). Oscules (4–10 mm in diameter) apical on digitations with a very delicate transluscent collar (2–4 mm) sometimes evident in living specimens; inhalant apertures (30–50 µm in diameter) scattered. Choanosome lax with ovoid choanocyte chambers (70 µm in diameter). Skeleton as a three-dimensional network of irregular polygonal meshes (100–800 µm) with primary fibres extremely variable in size (60–300 µm) constantly and heavily filled by foreign material; secondary ones (20–40 µm) with light and laminated spongin almost regularly free of debris or with scattered grains. Reproduction reported in June.

Cave, coralligenous community, artificial reefs, rocky/muddy/detritic bottom, lagoon, Posidonia oceanica meadow. Bathymetric range 1–100 m.

Blava, Meda Petita, Petita de la Vaca, Blue, Misidacis caves (Balearic Sea); Galatea*, Falco*, Bisbe* caves (Sardinian Sea); Béar, Troc, Endoume caves (Gulf of Lions), Bergeggi Cave (Ligurian Sea); Taccio Vecchio 1 Cave-Lampedusa* (Sicily Channel); Sifone Cave (Ionian Sea); Croatian, Columbera, Stražica caves (Northern Adriatic Sea); Sorrentino, Spido, Bue Marino caves (Southern Adriatic Sea); Farà Cave (Aegean Sea) (Boury-Esnault 1971; Pouliquen 1972; Pulitzer-Finali and Pronzato 1980; Bibiloni et al. 1984a, b; Bianchi and Morri 1994; Corriero et al. 2000; Novosel et al. 2002; Martì et al. 2004; Faresi et al. 2006; Turon et al. 2009; Denitto et al. 2010; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012; Cadeddu 2012; Gerovasileiou and Voultsiadou 2012).

Growth form irregular, massive; usually less than 10 cm in diameter, sometimes up to 15–20 cm in diameter and 2–3 cm in height. Colour in vivo (generally also preserved specimens) light grey to white; several, slightly perceptible, tone dominances are possible (light green to light brown). Consistency soft and fragile. Surface, shared by all species of the genus, as an irregular network of dense collagen fibres, sometimes with mineral debris. Inhalant apertures 80–120 µm in diameter. Oscules scattered (2–4 mm in diameter). Light collagen amount (fibrous reticulate) in the mesohyl. Flagellate chambers large. Skeleton reticulate, with irregular meshes (300–600 µm), and extremely fragile because of scanty spongin and extreme abundance of mineral granulation. Primary and secondary fibres (40–200 µm) not distinguishable or hierarchically organized.

Cave, rocky/detritic/muddy/sandy bottom, coralligenous community, Posidonia oceanica meadow, lagoon, artificial reefs, epibiotic on Pinna nobilis. Bathymetric range 1–200 m.

La Catedral, Tunel LLarg, Petita de la Vaca caves (Balearic Sea); Galatea*, Falco*, Bisbe* caves (Sardinian Sea); Béar, Niolon caves (Gulf of Lions); western-Zoagli, Piccola Zoagli-Chiavari, Tunnel Zoagli-Chiavari, Eastern Bonassola caves (Ligurian Sea); Mago, Gaiola, Misteri, Tuffo Tuffo, Mitigliano caves (Central Tyrrhenian Sea); Infreschi Cave (Southern Tyrrhenian Sea); Taccio Vecchio 1 Cave-Lampedusa*, Tunnel of Cani Islands (Sicily Channel); Gamberi* Cave (Ionian Sea); Croatian caves (Northern Adriatic Sea); La Regina Cave (Southern Adriatic Sea); Farà Cave (Aegean Sea) (Vacelet 1959; Sarà 1961a, 1962, 1964a; Labate 1964, 1965; Rützler 1966; Boury-Esnault 1971; Pulitzer-Finali and Pronzato 1976; Pansini et al. 1977; Pulitzer-Finali 1977; Bibiloni et al. 1984b, 1989; Ben Mustapha et al. 2002; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012; Cadeddu 2012; Gerovasileiou and Voultsiadou 2012).

Growth form encrusting (3–8 mm thick). Consistency fragile. Colour light grey to pale violet. Surface reticulate, conulose showing the internal aquiferous system in transparency. Conules 1–3 mm high, 3–5 mm apart. Oscules (5–7 mm) scattered, with a transparent collar. Skeletal network irregular with meshes (200–600 µm in diameter) formed by ascending primary fibres (70–90 µm in diameter) cored of foreign material, and secondary fibres (5–30 µm in diameter) generally lacking inclusions.

Cave, rocky bottom, artificial reefs, Posidonia oceanica meadow, lagoon, also. Frequently as encrusting patches also on other sponges or epibiotic on Pinna nobilis. Bathymetric range 1–100 m.

Galatea* Cave (Sardinian Sea); Lerici Cave (Ligurian Sea); Mago, Mitigliano caves (Central Tyrrhenian Sea); Taccio Vecchio 1 Cave-Lampedusa* (Sicily Channel); Gamberi*, Gymnasium* caves (Ionian Sea) (Pulitzer-Finali and Pronzato 1976, 1980; Pansini et al. 1977; Pulitzer-Finali 1977; Pansini and Pronzato 1982; Pronzato and Manconi 2011; Cadeddu 2012).

Growth form as a meshed irregular network of cylindrical processes (8–10 cm in length, 05–1 cm in diameter) lying on the substratum, rarely erected in some parts. Colour whitish to pale-light brown. Surface finely and irregularly conulose (0.3–1 mm high and apart). Oscules small (1 mm) and irregularly scattered. Skeleton network with irregular or quadrangular meshes (ca. 0.5 mm) with ascending primary fibres (80–120 µm) supporting conules. Primaries moderately charged of mineral materials; secondary fibres slim (15–40 µm) and almost free of sand grains.

Cave, rocky/detritic/muddy bottom, coralligenous community, lagoon. Bathymetric range 1–450 m.

Mitigliano Cave (Central Tyrrhenian Sea); Tunnel of Cani Islands, Tunnel of Tabarka (Sicily Channel) (Balduzzi et al. 1989; Ben Mustapha et al. 2002, 2003; Pronzato and Manconi 2011).

Growth form encrusting (6 × 4 cm, ca. 3–5 mm thick). Surface covered of small conules (0.8–1.2 mm apart) each with a slightly protruding fibre. Ectosome unarmoured. Oscules (0.8–1 mm in diameter) numerous, circular and irregularly scattered. Colour cream in vivo with the tips of conules whitish, clear brown in alcohol. Consistency fleshy, easily torn. Choanocyte chambers of the dysideid type, numerous, large (75–90 µm in diameter). Skeleton primary fibres heavily cored (125–150 µm in diameter), ascending singly from substratum to surface, rather regularly spaced, ending as conules. Secondary fibres (40–70 µm in diameter) generally clear of inclusions can have a poorly developed central core of foreign material.

Cave. Exclusively known from Raouché cave, along the Lebanese coast (Eastern Mediterranean Sea). Bathymetric distribution 2–5 m.

Raouché Cave (Levantine Basin) (Vacelet et al. 2007; Pronzato and Manconi 2011).

Growth form encrusting (1–5 mm in thickness). Consistency soft. Colour light brown to light grey. Surface finely conulose. Exhalant canals evident on the sponge surface, converging in scattered oscules 1–2 mm in diameter. Flagellate chambers from oval to rounded (50–90 µm in diameter). Skeleton typically dendritic with fibres (1–3 mm in height ca. 160 µm in diameter at their base) rising from a basal plate. Fibres laminated, normally with a single apex supporting a conule but, in some cases, arborescent with 2–3 branches. Fibres evidently cored with irregularly dense foreign debris, mainly spicule fragments.

Cave, rocky bottom, artificial reefs. Bathymetric range 1–30 m.

Niolon Cave (Gulf of Lions); Monte Vico, Secca delle Formiche-Vivara, Mago caves (Central Tyrrhenian Sea) (Laborel and Vacelet 1958; Pulitzer-Finali and Pronzato 1976; Pansini et al. 1977; Pulitzer-Finali 1977; Pronzato and Manconi 2011).

As for diagnostic traits the genus Pleraplysilla is anomalous among the Dictyoceratida, for the trait ‘dendritic not anastomosing skeleton’. As for the taxonomic status Pleraplysilla minchini is regarded by Vacelet (1959) as a synonym of Pleraplysilla spinifera. Later authors, as Cabioch (1968) and Borojevic et al. (1968), considered both species as valid. The material available for our study seems to confirm a specific divergence between the two. Pleraplysilla spinifera is generally recognizable at sight by the very pronounced, spaced conules. Its fibres reach a length of 12 mm, with a thickness of 450 µm near the base; they are generally branched; sometimes more than one fibre starts from a common basal plate; the inclusions are mostly closely-packed sand grains. In Pleraplysilla minchini the fibres are less widely spaced, they reach not more than 3 mm in length and a diameter of 160 µm near the base; they are generally not branched and there is a prevalence of sponge spicules in their inclusions.

Growth form encrusting, up to 2 cm thick, as irregular patches (several cm in diameter) characterized by a smooth and conulose mucous surface. Conules very evident, up to 8–10 mm in height. Colour from whitish to very light brown. Consistency very soft. Exhalant and inhalant apertures (up to 1 mm in diameter) irregularly scattered on the surface. Skeleton of dendritic fibres generally arborescent with 2–5 branches. Each fibre with a basal plate strictly adhering to the substrate. Spongin laminated and cored by sand grains and spicule fragments. These stout fibres (1.5–2.0 mm in height) can reach 400 µm in diameter at their base, with a sandy core of 80 µm. Fibres usually light yellow and transparent show, in many cases, a red-brown colour due to microscopic algae.

Cave, rocky/detritic/muddy bottom, red coral bank, coralligenous community, artificial barriers, boulders, Posidonia oceanica meadow. In many cases massive specimens, not over 5 cm in diameter, of this species are epibiotic on gorgonians and Pinna nobilis. Bathymetric range 1–500 m.

Blava, La Catedral, Blu, Misidacis, Meda Petita, Petita de la Vaca caves (Balearic Sea); Galatea*, Falco*, Bisbe* caves (Sardinian Sea); Béar, Endoume, Figuier, Tremier, Niolon, Bagaud caves (Gulf of Lions); Secca delle Formiche –Vivara Cave (Central Tyrrhenian Sea); Gamberi* Cave (Ionian Sea); Croatian caves (Northern Adriatic Sea); Piccolo Ciolo, Marinella, Principessa caves (Southern Adriatic Sea); Farà, Agios Vasilios, Vouliagnemi caves (Aegean Sea) (Vacelet 1959; Boury-Esnault 1971; Pouliquen 1972; Pulitzer-Finali and Pronzato 1976; Pulitzer-Finali 1977; Bibiloni et al. 1984a, 1989; Harmelin et al. 2003; Martì et al. 2004; Bussotti et al. 2006; Turon et al. 2009; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012; Cadeddu 2012; Gerovasileiou and Voultsiadou 2012).

Among the Dictyoceratida, the genus Pleraplysilla has a dendritic not anastomosing skeleton.

Growth form partially erect (ca. 5–10 cm in diameter) with quite cylindrical ramifications (0.8–1.5 cm in thickness) anastomosing in a lax irregular network growing flat on the substrate with few short uprising processes. Colour light to dark grey. Consistency finely sandy. Inhalant and exhalant apertures not evident. Skeleton network irregularly reticulate with large meshes (100–500 µm in diameter) of primary (120–200 µm) and secondary (30–90 µm) fibres. Primaries with a dark pith rich of foreign inclusions; secondaries laminated and converging in several cribrose plates. Spongin filaments abundant (3.5–5.0 µm thick), with a terminal knob (8–10 µm).

Cave, detritic and rocky bottom, coralligenous community. Bathymetric range 1–110 m.

Blava, Calamars, La Catedral, Meda Petita, Petita de la Vaca, Blue, Misidacis caves (Balearic Sea); Bagaud Cave (Gulf of Lions); Azzurra, Mago, Misteri caves (Central Tyrrhenian Sea); Taccio Vecchio 1 Cave-Lampedusa* (Sicily Channel); Castro Marina, Mazzere*, Gamberi*, Gymnasium* Caves (Ionian Sea); Croatian, Stražica caves (Northern Adriatic Sea); Viole, Spido caves (Southern Adriatic Sea); Agios Nicolaos Cave (Aegean Sea) (Pansini et al. 1977; Pulitzer-Finali and Pronzato 1980; Bibiloni et al. 1984a, b, 1989; Uriz et al. 1992; Novosel et al. 2002; Harmelin et al. 2003; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012).

Growth form massive, lobate, with large size (20-30 cm in diameter and 10–15 in height). Each lobe usually bears a large oscule (30–60 mm in diameter), sometimes at the end of a short funnel (1 cm high). Colour medium to dark grey in vivo. Surface covered by a slim layer of very fine and regular mineral sediment engulfed in a slender regular network showing a lighter colour. Conules (1–2 mm in height) regularly distributed, 24 mm apart. Choanosomal skeleton rust coloured and rich in fibres and filaments. Skeleton network of cored primary fibres (200–250 µm in diameter) and free (or almost free) secondary fibres (100–200 µm). Filaments (9–13 µm) with an oval knob (15–22 µm).

Cave, detritic and rocky bottom, coralligenous community. Specimens of this species are frequently covered by large specimens of Haliclona (Reniera) cratera (Schmidt 1862). Bathymetric range 1–150 m.

Blava, La Catedral, J1, Blue, Misidacis caves (Balearic Sea); Galatea*, Falco*, Bisbe* caves (Sardinian Sea); Endoume, Figuiers caves (Gulf of Lions); Western-Zoagli Cave (Ligurian Sea); Lacco Ameno, Tuffo Tuffo caves (Central Tyrrhenian Sea); Monastir, Salakta caves (Sicily Channel); Mazzere* Cave (Ionian Sea); Croatian caves (Northern Adriatic Sea); Trypia Spilia, Ftelio, Farà, Madhes, Alikes caves (Aegean Sea) (Sarà 1960a, 1964a; Rützler 1966; Pouliquen 1972; Bibiloni et al. 1989; Ben Mustapha et al. 2003; Martì et al. 2004; Turon et al. 2009; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012; Cadeddu 2012; Gerovasileiou and Voultsiadou 2012).

This specie was described on behalf of two fragments of “an irregular massive specimen with osculiferous lobes”. Conules few, irregularly high and scattered. Colour reported as “light” in alcohol. Consistency lax, similar to Cacospongia species. Dermal membrane reinforced by rare sand grains, easy to remove. Skeleton network of primary fibres cored and anastomosed with secondaries free of foreign materials (dimensions not reported in the original description). Filaments very rare (9–13 µm in diameter) with an irregular globular termination (25–45 µm in diameter). Flagellate chambers 25–35 µm in diameter.

Cave. Bathymetric range 1–3 m.

Only known from a few caves in the Aegean Sea at Kastelorizo (type locality), Trypia, Farà and Agios Vasilios caves (Vacelet 1961a; Voultsiadou-Koukoura and Koukouras 1993; Pronzato and Manconi 2011; Gerovasileiou and Voultsiadou 2012).

Growth form massive, rounded, ca. 10 × 5 × 5 cm. Consistency firm and elastic. Colour in the preserved state is from beige to mid brown; living specimens appear a little bit darker. Surface conulose with blunt conules (ca. 1–2 mm high, 1–3 mm apart) connected with each other by a raised, honeycombed reticulation with meshes (ca. 80 µm in diameter) quite conspicuous at bare eye, made of fine particles of sand and a concentration of filaments. Oscules (2–5 mm in diameter) scattered, with elevated margins. Skeleton reticulate with meshes 200 to 600 µm in diameter. Main fibres (50–80 µm in thickness) not fasciculate, moderately cored by foreign matter (sand and spicule fragments). Secondary fibres (20–80 µm thick) irregularly trellis-like, free of inclusions. Filaments ca. 5 µm thick.

Cave, muddy and rocky bottom. Here we report a new record from a submerged cave in the NW-Sardinian karst. Bathymetric range shallow water up to 80 m.

Falco* Cave (Sardinian Sea) (Cadeddu 2012).

Growth form massive up to 20–25 cm in height and diameter. Colour also notably variable: from light or dark grey, to light or dark brown and light or dark violet. Consistency elastic and strong. Dimension and density of conules variable, not representing a valid diagnostic character. Oscules arranged in disorder. Skeleton network of primary (150–250 µm) fibres cored by opaque foreign materials supporting conules at their apices; secondary fibres mostly free of inclusions, and highly variable in diameter (10–200 µm).

Cave, coralligenous community, detritic and rocky bottom, Posidonia oceanica meadow, lagoon, epibiotic on Pinna nobilis. Bathymetric range 0–450 m.

Blava, Blue, Meda Petita, Petita de la Vaca caves (Balearic Sea); Galatea*, Falco*, Bisbe* caves (Sardinian Sea); Niolon Cave (Gulf of Lions); Punta Manara, Western-Bonassola caves (Ligurian Sea); Azzurra, Isolotto, Giannutri, Ponza, Monte Vico, Mago, Secca delle Formiche-Vivara, Misteri, Scraio-Vico Equense, Mitigliano caves (Central Tyrrhenian Sea); Maratea, Azzurra, Leone caves (Southern Tyrrhenian Sea); Taccio Vecchio 1 Cave-Lampedusa* (Sicily Channel); Castro Marina, Porto Cesareo, Mazzere*, Gymnasium* caves (Ionian Sea); Croatian, Vrbnik-Krk, Columbera caves (Northern Adriatic Sea); Pagliai, Viole, Bue Marino, Regina, Torre Incine, Piccolo Ciolo, Marinella, Principessa caves (Southern Adriatic Sea); Gournia Cave (Crete, Aegean Sea) (Vacelet 1959; Sarà 1962, 1964a; Labate 1965; Pulitzer-Finali and Pronzato 1976, 1980; Pansini et al. 1977; Pulitzer-Finali 1977; Pansini and Pronzato 1982; Bibiloni et al. 1984a, b; Balduzzi et al. 1989; Corriero et al. 2000, 2004; Arko-Pjevac et al. 2001; Martì et al. 2004; Bussotti et al. 2006; Faresi et al. 2006; Turon et al. 2009; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012; Cadeddu 2012).

Growth form massive, irregular (up to 12 × 15 cm in diameter). Surface regularly conulose (1 mm in height, 1–2 mm apart). Skeleton network light brown, fragile, reticulate with more or less square meshes from the sponge base to the surface. Almost parallel ascending primary fibres (200–300 µm in diameter) free from foreign inclusions, with apices supporting conules. Each primary fibre as a bundle of some (2–5) uncored secondary fibres (50–100 µm in diameter) joined by conspicuous spongin tracts and cribrose plates. Filaments less than 3 µm thick, abundant, and whitish.

Cave, rocky bottom, Posidonia oceanica meadow, coralligenous community. Bathymetric range 1–100 m.

Blue, La Catedral, J1, Meda Petita, Petita de la Vaca, Misidacis caves (Balearic Sea); Bagaud, Endoume, Figuier, Trèmies caves (Gulf of Lions); Zoagli-Chiavari Cave (Ligurian Sea); Misteri, Gaiola, Tuffo Tuffo caves (Central Tyrrhenian Sea); Molare caves (Southern Tyrrhenian Sea); Monastir, Salakta caves (Sicily Channel); Leuca caves (Ionian Sea); Stražica Cave (Northern Adriatic Sea); Arenile, Pagliai, Viole, Coccodrillo, Cala Tonda, Bue Marino, Rondinelle, Pecore, Regina caves (Southern Adriatic Sea) (Sarà 1958, 1959, 1961a, b, 1962, 1964a, 1968; Labate 1965; Melone 1965; Rützler 1966; Pouliquen 1972; Bibiloni et al. 1984a, 1989; Corriero et al. 2000; Novosel et al. 2002; Ben Mustapha et al. 2003; Harmelin et al. 2003; Martì et al. 2004; Pronzato and Manconi 2011).

The present description is based on the holotype LMJG 15499 (Museum Joanneum of Graz, Austria), O. Schmidt collection, from Lesina (Adriatic Sea), and other specimens belonging to the Schmidt’s collection preserved in the same museum. The study in depth of this dry holotype material resulted in the evidence that it does not belong to the genus Ircinia but perfectly matches the genus Sarcotragus. The holotype is, probably, a fragment of a bigger specimen and does not exceed 15 cm in diameter; no traces of dermal membrane or choanosomal architecture are visible, suggesting that it can be a beached specimen. The type material of Pallas Spongia fasciculata is missing and the single specimen of Ircinia fasciculata belonging to the Schmidt’s collection (NHMG 15499) must be ascribed to the genus Sarcotragus. Pronzato et al. (2004) investigated the species formerly named Ircinia fasciculata (Pallas, 1766); the result was that Ircinia variabilis (Schmidt, 1862) became the type species of the genus Ircinia Nardo, 1833 and the specimen LMJG 15499, of Ircinia fasciculata, was moved under the genus Sarcotragus Schmidt, 1862 affirming that: “a further study will decide if this species is a good one or a synonym”. Pronzato et al. (2004) focused the problematic status of the taxon but did not describe the species. Here a new combination for Sarcotragus fasciculatus is proposed. Sarcotragus fasciculatus is clearly different from the other species ascribed in the genus, also when compared with extra-Mediterranean species (Pronzato et al. 2004) because all its fibres are free of inclusions and primary ones are formed by “fascicules of secondaries”.

Growth form irregularly massive to globular (up to 1 m in diameter, 50 cm in height); oscules large (0.5–1 cm in diameter) with a short collar, often grouped in a central depression at the top of the body. Consistency soft and strong. Colour is medium grey, but brown or black varieties have been also recorded (Vacelet 1959). Surface is smooth or covered by several epizoans. Conules are 2–3 mm high and 10–15 mm apart. Dry specimens become very hard and smaller (1/5) than living ones, also colour changes regularly into black. The skeleton does not differ from the other Mediterranean species belonging to the genus; the main skeleton composed by a reticulate network of primary (ca. 100–200 µm in diameter) and secondary (ca. 50–100 µm in diameter) fibres. Filaments abundant (1–3 µm in diameter).

Cave, rocky, detritic and muddy bottom, coralligenous community. Bathymetric range 3–400 m.

Blava, Calamars, Meda Petita, Petita de la Vaca caves (Balearic Sea); Mago Cave (Central Tyrrhenian Sea); Taccio Vecchio 1 Cave-Lampedusa*, Tabarka Tunnel (Sicily Channel); Croatian caves (Northern Adriatic Sea); Viole Cave (Southern Adriatic Sea); Chios 213, Trypia Spilia, Farà, Agios Vasilios caves (Aegean Sea) (Pansini et al. 1977; Bibiloni et al. 1984a; Uriz et al. 1992; Voultsiadou-Koukoura and Koukouras 1993; Ben Mustapha et al. 2002; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012; Cadeddu 2012; Gerovasileiou and Voultsiadou 2012).

Growth form massive (10 × 10 cm to 5 × 5 cm) and irregular in the basal portion with 5 to 10 peculiar, unequal, hollow, conical processes (1 to 3 cm high and 1 to 2 cm wide at their base) bearing an apical, circular oscule 1 to 3 mm in diameter. Consistency firm and elastic, difficult to tear. Colour in formalin from light brown to dark violet-brown to rarely greyish azure in vivo (Mitigliano cave). Dermal membrane with fine particles of sand. Conules ca. 0.5 mm in height, rather irregularly distributed (1 to 3 mm apart). Skeleton reticulate with meshes 2–3 mm in diameter. Primary fibres with fasciculate architecture, with a central fibre (50 to 150 µm thick) cored by small inclusions (mainly sand) irregularly surrounded by a trellis of thinner fibres (20 to 40 µm thick), free of inclusions. These complex fibres assume here and there the shape of a perforated plate (400–700 µm in diameter). Secondary fibres simple, moderately cored by foreign matter, generally narrow at their centre and anastomosing to the main fibres by root-like processes. Filaments up to 6.5 µm in thickness.

Cave, rocky bottom, coralligenous community. Bathymetric range 8–120 m.

Mitigliano Cave (Central Tyrrhenian Sea) (Pansini and Pronzato 1982; Balduzzi et al. 1989; Pronzato and Manconi 2011).

Growth form regular, massive, rarely exceeding 10 cm in diameter. Colour black or dark grey in vivo. Consistency strong, relatively elastic. Surface finely conulose (1–2 mm in height and 2–3 mm apart). Oscules (up to 1 cm in diameter) irregularly scattered. Skeleton network reticulation of ascending primary fibres (90–180 µm in diameter) with a fibrous narrow core free of inclusions or bearing only rare spicules. Secondary fibres (50–100 µm in diameter) uncored and laminated. Filaments (0.7–2.0 µm in diameter) very abundant giving a strong consistency.

Cave, rocky, detritic and muddy bottom, coralligenous community, lagoon, Posidonia oceanica meadow, epibiotic on Pinna nobilis. Bathymetric range 1–60 m.

Blava, La Catedral, Meda Petita, Petita de la Vaca caves (Balearic Sea); Bear, Troc, Endoume caves (Gulf of Lions); Isolotto, Mago, Tuffo Tuffo caves (Central Tyrrhenian Sea); Porto Cesareo Cave (Ionian Sea); Croatian, Stražica caves (Northern Adriatic Sea); Viole, Bue Marino, Piccolo Ciolo, Marinella, Principessa caves (Southern Adriatic Sea); Ftelio Cave (Aegean Sea) (Rützler 1966; Boury-Esnault 1971; Pouliquen 1972; Pulitzer-Finali and Pronzato 1976, 1980; Pansini et al. 1977; Pulitzer-Finali 1977; Bibiloni et al. 1984a, 1989; Corriero et al. 2000, 2004; Bussotti et al. 2006; Novosel et al. 2002; Turon et al. 2009; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012; Gerovasileiou and Voultsiadou 2012).

Growth form massive, cushion shaped, lobose (6 to 30 cm² surface area, ca. 5 mm avg thickness). Colour light brown, lighter in formalin. Consistency soft, spongy and compressible. Surface conulose with conules ca. 1 mm in height and 2–4 mm apart. Oscules few (2–4 mm in diameter). Ostia visible in some areas with a diameter of 50–200 µm. Ectosome (100–350 µm in thickness) detachable and armoured with sand grains and foreign spicules.

Ascending primary fibres (50–80 µm in diameter) cored with foreign material to such a degree that sometimes spongin is hardly visible. Foreign material usually sand grains mixed with low amounts of spicules, although some fibres cored exclusively with spicules. Primary fibres connected to a dense, irregular, network of secondary fibres which, in the vicinity of the primary fibres, has the form of a perforated plate. Secondary fibres (10–40 µm in diameter) often with rounded or broadly acute free tips, thin and hardly anastomosing. The secondary network, in its greater part, resembles an unwound clew.

Cave, rocky bottom. Bathymetric range 3–15 m.

Youra Cave (Sporades Islands, Northern Aegean Sea) (Voultsiadou-Koukoura et al. 1991; Pronzato and Manconi 2011).

Growth form massive, rounded. Colour in vivo dark grey. Surface with large, sparse conules. Oscules scattered or grouped at the top surface, pre-oscular cavities extremely developed, large subdermal canals radially arranged at oscula. Large cavernous cavities (1–4 cm) irregularly scattered in the choanosome. Skeleton reticulate with ascending main fibres supporting the conules. Primaries (60–100 µm in diameter) twisted, with inclusions (fragments of spicules and mineral granules). Primaries present exclusively as main axis of conules, towards the surface, in some specimens/populations. Secondaries (20–30 µm in diameter) abundant, forming a dense network, without inclusions.

Cave, coralligenous community, Posidonia oceanica meadow, rocky/detritic/muddy bottom. Bathymetric range 1–200 m.

Blava, Blue, La Catedral caves (Balearic Sea); Endoume, Figuier, Trèmies caves (Gulf of Lions); Azzurra, Mago caves (Central Tyrrhenian Sea) (Pouliquen 1972; Pulitzer-Finali and Pronzato 1976, 1980; Cinelli et al. 1977; Pansini et al. 1977; Pulitzer-Finali 1977; Bibiloni et al. 1989; Martì et al. 2004; Turon et al. 2009; Pronzato and Manconi 2011).

Growth form vase- or fan-shaped, large (up to over 1 m). Surface finely conulose, inhalant and exhalant openings of the aquiferous system on the outer and inner sides, respectively, of the vase, or on the opposite sides of the fan. Wall 5–10 mm thick. Inhalant apertures large and irregular. Oscules small with a diameter ca. 1.5 mm and grouped in clubs regularly scattered. Colour in vivo from grey to brown. Surface conulose. Ectosomal skeleton covered by a dermal membrane rich of sand, as a network of secondary fibres (15–20 µm in diameter) connected to the apices of primaries. Choanosomal skeleton as an irregular network of secondaries (20–40 µm in diameter) with evident tracts of primary fibres (50–80 µm in diameter) extended between inner and outer surfaces. Primary fibres cored by mineral inclusions.

Cave, rocky/muddy/detritic bottom. Bathymetric range from shallow water to 22–300 m.

Galatea*, Falco*, Bisbe* caves (Sardinian Sea); Trèmies Cave (Gulf of Lions); Bergeggi Cave (Ligurian Sea) (Pouliquen 1972; Bianchi and Morri 1994; Manconi et al. 2011; Pronzato and Manconi 2011; Cadeddu 2012).

Growth form irregularly lobate, rarely larger than 15–20 cm. Oscules (2 mm in diameter) on each lobe, with evident very long converging exhalant canals. Consistency soft and strong. Colour whitish to light brown. Conules small and regular. Primary fibres (40–60 µm in diameter) sometimes showing a fibrous opaque core, avoiding inclusion or with rare spicule fragments. Secondary fibres (20–35 µm in thickness) connecting primary ones in a regular network; a second superficial network is formed by thinner (4–10 µm) fibres. Skeleton extremely soft. The specific name refers to the silky sponge’s surface with an external membrane smooth and translucent.

Cave, coralligenous community. Bathymetric range 0–15 m.

Falco*, Bisbe* caves (Sardinian Sea); Endoume, Figuiers caves (Gulf of Lions); Leuca caves (Ionian Sea); Croatian caves (Northern Adriatic Sea); Farà, Agios Vasilios caves (Aegean Sea)(Sarà 1968; Pouliquen 1972; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012; Cadeddu 2012; Gerovasileiou and Voultsiadou 2012).

Growth form massive-lobate, surface finely conulose, single oscules scattered or at the apex of lobes, pre-oscular cavities well evident. Colour in vivo from light grey to black. Ectosomal skeleton as apices of primary fibres joining secondary fibres to form the conical reticulum which supports the conules. Choanosomal skeleton: network dense with irregular polygonal meshes of secondaries joining to form ascending primaries. Primary fibres (50–100 µm in diameter) typically twisted with ornamentations as parallel ridges along the main fibre axis mainly developed and evident towards the surface, cored with sand grains and spicules. Secondaries (20–35 µm in diameter) with ornamentations as parallel ridges along the main fibre axis, twisted and characterised by concentric layers of compact spongin surrounding the compact axial core without inclusions.

Cave, coralligenous community, rocky/detritic/muddy/sandy bottom, lagoon, coralligenous community, Posidonia oceanica meadow. Bathymetric range 1–70 m.

Meda Petita, Petita de la Vaca caves (Balearic Sea); Falco*, Bisbe* caves (Sardinian Sea); Endoume, Figuiers, Trèmies, Niolon, Bagaud caves (Gulf of Lions); Bergeggi, Eastern-Bonassola, Zoagli-Chiavari caves (Ligurian Sea); Azzurra, Isolotto, Mago, Misteri, Tuffo Tuffo caves (Central Tyrrhenian Sea); Taccio Vecchio 1 Cave-Lampedusa*, Cani Islands Tunnel (Sicily Channel); Leuca caves (Ionian Sea); Croatian, Vrbnik-Krk caves (Northern Adriatic Sea); Pagliai, Regina caves (Southern Adriatic Sea) (Laborel and Vacelet 1958; Sarà 1959, 1964a; Vacelet 1959; Labate 1965; Rützler 1966; Pouliquen 1972; Pulitzer-Finali and Pronzato 1976, 1980; Cinelli et al. 1977; Pansini et al. 1977; Pulitzer-Finali 1977; Bibiloni et al. 1984a, b; Bianchi et al. 1986; Arko-Pjevac et al. 2001; Ben Mustapha et al. 2002; Harmelin et al. 2003; Manconi et al. 2011; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012; Cadeddu 2012).

Growth form encrusting (ca. 2–5 cm in diameter), rarely massive (up to 10–15 cm), usually emerging from the substratum only with inhalant and exhalant funnels (5–15 mm high, 3–5 mm in diameter). Sponge surface irregularly conulose (1–2 mm high, 24 mm apart). Colour from light to very dark brown. Primary fibres (40–50 µm) cored by mineral debris, extremely rare and often absent; secondaries extremely variable (10–50 µm).

Cave, coralligenous community, detritic/muddy bottom, lagoon, artificial reef, Posidonia oceanica meadow, epibiotic on Pinna nobilis. Generally covered by epibionts in turbulent superficial water. Bathymetric range 1–50 m.

La Catedral, J2, Blue, Meda Petita, Petita de la Vaca, Misidacis caves (Balearic Sea); Galatea*, Falco*, Bisbe* caves (Sardinian Sea); Bear, Troc, Endoume, Figuiers, Trèmies caves (Gulf of Lions); Punta Carega, Manara, Zoagli-Chiavari caves (Ligurian Sea); Azzurra, Isolotto, Mago, Lacco Ameno, Misteri, Gaiola, Tuffo Tuffo, Mitigliano caves (Central Tyrrhenian Sea); Porto Cesareo Cave (Ionian Sea); Croatian caves (Northern Adriatic Sea); Pagliai, Viole, Pecore, Arenile, Coccodrillo, Rondinelle, Bue Marino, Piccolo Ciolo, Marinella, Regina caves (Southern Adriatic Sea); Trypia Spilia, Farà, Ftelio caves (Aegean Sea) (Sarà 1960a, b, 1961a, 1964a; Labate 1965; Rützler 1966; Boury-Esnault 1971; Pouliquen 1972; Pansini et al. 1977; Pulitzer-Finali and Pronzato 1980; Pansini and Pronzato 1982; Bibiloni et al. 1984a, 1989; Balduzzi et al. 1989; Corriero et al. 2000, 2004; Martì et al. 2004; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012; Cadeddu 2012; Gerovasileiou and Voultsiadou 2012).

Massive to globular growth form, small size, usually not over 15 cm in diameter. Surface softly hairy, densely conulose with very long conules (2–3 mm high and less than 1 mm apart) sometimes a single conule supported by 2–3 converging primary fibres. Oscules not evident and located in small deep superficial depressions. Colour in vivo never reported. Consistency very soft, elastic and strong. Skeleton as a network of regular meshes (100–200 µm) with primary fibres bearing very rare inclusions (particularly fragments of spicules) and secondaries completely free of inclusions; primary fibres typically formed by anastomosing secondaries in fascicules (50–80 µm in diameter).

Cave, rocky bottom, coralligenous community. Bathymetric range 1–40 m. Here we report a new record from the Bisbe Cave in the NW-Sardinian karst.

Bisbe* Cave (Sardinian Sea); Salakta Caves (Sicily Channel) (Ben Mustapha et al. 2003; Manconi et al. 2011; Pronzato and Manconi 2011; Cadeddu 2012).

It is a problematic species, indeed the Schmidt’s type specimen (naked skeleton, Cyprus, no further data), preserved in the Graz Museum (LMJG 15470/0) is clearly a Spongia officinalis. Moreover many authors, in various papers, described this species differently, contributing to determine its problematic taxonomic status. In contrast with that, the commercial “Zimoccas” really belong to a species distinctly different from the other specieshitherto ascribed tothe genus Spongia as reported also by Schmidt (1862), Schulze (1879a) and de Laubenfels (1948). As a consequence the Graz Museum type needs to be carefully studied. The present description is based on the specimens TRG Ker 346, DTRG Ker 347, Jerba-El-Jem (Tunisia), 3–4 m, soft bottom, August 2006. Many traders consider “Zimocca” as the best commercial Mediterranean sponge.

Growth form massive, lobate, 10–25 cm in diameter. Consistency soft and spongy, easy to tear off in vivo and friable when dry. Colour dark grey with whitish, bluish and magenta tinges. Surface smooth, regularly conulose (1–1.5 mm in height, 1–2 mm apart), forming regular characteristic “circular craters”. Oscules scattered, small and single, upwards of 1 mm in diameter. Flagellate chambers spherical, 30–45 µm in diameter. Skeleton network reticulate with regular meshes (300–600 µm). Primary ascending fibres (80–120 µm) cored by mineral debris; secondaries abundant, free of inclusions, transparent and uncored. Skeleton soft when hydrated and brittle when dry.

Cave, coralligenous community, rocky/detritic/muddy bottom, Posidonia oceanica meadow, lagoon, epibiotic on Pinna nobilis. Bathymetric range 1–100 m.