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Radiospongilla cfr. philippinensis (Annandale, 1909) Figs 1 a, 2, 3, 4, 5; Tables 1, 2, 3 Material examined. Four specimens NTM ZOO 5052, NTM ZOO 5056, NTM ZOO 5063, NTM ZOO 5069. Dry shore of a billabong, Mamukala Wetlands, 12��38���S 132��35���E, 7 km East of the South Alligator River, South off the Arnhem Highway, Kakadu National Park (Fig. 1, site a), 10.vii.1998, R. Manconi leg. Some slides and stubs (DTRG-FW571a, b, c, d) are deposited in the authors��� collection. Additional material. NTM Z001431, Tom Lagoon, NT, 16��22���S 134��50���E, Latz leg., 3.i.1971, large clusters on roots (DTRG-FW706); NTM Z001435, unknown location, Stn n. FW-0016 (DTRG-FW707) Comparative material. Radiospongilla sceptroides, AM Z2837, neotype, Merrika River, Nadgee Faunal Reserve near Womboyne (37��15���S, 149��55���E), New South Wales, Australia, on large rock, 0.5 m depth, 6.iii.1958, leg. F. Hersey, det. Penney & Racek (DTRG-FW542). Spongilla philippinensis, BMNH 34.4.28.1 box 13.III. C, alcohol, leg. L.E. Cheesman, Lake Sentani, Dutch New Guinea (DTRG-FW382). Spongilla sceptroides Haswell, BMNH 86.8. 27.665, box 13.III. C, alcohol, Brisbane, Australia (DTRG-FW387), BMNH 86.8.27.658, box 5, dry, leg. von Lendenfeld, Kakalum River, Australia (DTRG-FW409). Spongilla cerebellata Bowerbank, 1863, schizotype, Bowerbank collection, leg. Brudley, Dominion of Nizam (DTRG- FW412). Description. Growth form encrusting (5���6 mm in diameter, 2���5 mm thick) to cushion-shaped (3.5 cm in diameter, 1 cm thick). Consistency extremely fragile (dry specimens are, at present, completely fragmented due to their extremely fragile consistency). Colour whitish in dry condition. Oscules scattered. Ectosomal skeleton with no special architecture. Choanosomal skeleton irregularly reticulate network, with ascending paucispicular primary fibres and vague secondary tracts. Spongin scanty. Megascleres acanthoxeas of two size classes straight to slightly bent, from stout [232���302 (266��17) x 6���13 (9.28��0.96) ��m] to slender [188���226 (208��13) x 2.9���5.8 (5.24��1.06) ��m] ornamented by large, straight to curved variably dense small spines except at the tips. Microscleres absent. Gemmules subspherical (600���750 ��m in diameter) single to grouped (2���3) scattered in the skeletal network at the sponge basal portion. Foramen in a more or less conical depression, simple, without collar, with brown, slender porus tube. Gemmular theca trilayered with gemmuloscleres in a single layer more or less radially embedded (NTM ZOO 5052, 5056, 5063, 5069) to in double layer both tangentially arranged at theca surface and radially embedded in it (NTM Z001431, NTM Z001435). Outer gemmular surface hispid due to the emerging distal apices of gemmuloscleres. Pneumatic layer with vague chambers of spongin to with welldeveloped polygonal chambers. Inner layer sublayered of compact spongin. Gemmuloscleres [122���174 (148��12) x 2.3���8.7 (5.25��2.26) ��m] straight to slightly curved of two types from slender acanthoxeas abruptly pointed with few small scattered spines except at the tips, to stout acanthostrongyles with large straight spines scattered along the axis, and curved spines densely clustered at the tips. Habitat. Several dry sponges were discovered along the shore of an almost dry billabong in shaded areas on the painted metallic piers of a bird-watching platform and on surrounding dry timbers and bushes between the platform and the path (Fig. 2). Data confirm the typical growth mode of this species on natural and artificial substrata (Racek 1969). Geographic distribution. The geographic range of R. philippinensis is from the Philippines to northern Australia (Tables 1���2). The present record in Kakadu National Park confirms the presence of this species in coastal tropical-subtropical areas of the north, western and southern Australia (Racek 1969). On the other hand R. streptasteriformis Stanisic, 1979 is apparently endemic to the Northern Territory (Tables 1���2) (Stanisic 1979) whereas R. pedderensis Osborne, Forteath & Stanisic, 2008 is endemic to Tasmania (Osborne et al. 2008). The doubtful presence in Australia of R. crateriformis (Potts, 1882) is discussed by Racek (1969). The biogeographic pattern of the speciose Radiospongilla (18 species) is in the Australasian, Afrotropical, Neotropical, Nearctic, Oriental, and Palaearctic regions (Fig. 5) (Penney & Racek 1968; Manconi & Pronzato 2002, 2007). Remarks. In his synopsis on Australian freshwater sponges Racek (1969) clarified the taxonomic status of Radiospongilla philippinensis (previously a junior synonym of R. sceptroides) as a valid species (Penney & Racek 1968). On the basis of comparative analysis of specimens from Kakadu National Park bearing gemmules with a single layer of radial gemmuloscleres are here ascribed to R. cfr. philippinensis (Table 3) because they diverge from descriptions of Philippine and other Australian material (Annandale 1909ab). Also additional material from the NTM bearing gemmules with two layers of gemmuloscleres i.e. tangentially and radially arranged in the gemmular theca is here ascribed to R. cfr. philippinensis (Table 3). Radiospongilla Radiospongilla philippinensis cfr. philippinensis Gemmuloscleres acanthostrongyles acanthostrongyles acanthostrongyles acanthostrongyles ��m 80���122 x 31 105���180 x 4���5 acanthoxeas acanthoxeas 102���149 x 4.5���7 122���174 x 2.3���8.7 Gemmular tangential spicules in irregularly radial irregularly radial theca single layer spicules in single tangential and radial spicules in spicules in single layer double layer layer References *Annandale 1909ab Racek 1969 Present paper Present paper # Gee, 1931b GENUS Pectispongilla ANNANDALE , 1909, Published as part of Manconi, R., Cubeddu, T. & Pronzato, R., 2016, Australian freshwater sponges with a new species of Pectispongilla (Porifera: Demospongiae: Spongillida), pp. 61-76 in Zootaxa 4196 (1) on pages 65-69, DOI: 10.11646/zootaxa.4196.1.3, http://zenodo.org/record/167679, {"references":["Racek, A. A. (1969) The freshwater sponges of Australia (Porifera: Spongillidae). Australian Journal of Marine and Freshwater Research, 20, 267 - 310.","Stanisic, J. (1979) Freshwater sponges from the Northern Territory (Porifera: Spongillidae). Proceedings of the Linnean Society of North South Wales, 103 (2), 123 - 130.","Osborn, A. W., Forteath, G. N. R. & Stanisic, J. (2008) A new species of freshwater sponge (Porifera: Spongillidae) of the genus Radiospongilla from Lake Pedder in Tasmania. Papers and Proceedings of the Royal Society of Tasmania, 142 (2), 39 - 44.","Penney, J. T. & Racek, A. A. (1968) Comprehensive revision of a world-wide collection of freshwater sponges (Porifera: Spongillidae). United States National Museum Bulletin, 272, 1 - 184.","Manconi, R. & Pronzato, R. (2002) Spongillina n. subord. Lubomirskiidae, Malawispongiidae n. fam., Metaniidae, Metschnikowiidae, Palaeospongillidae, Potamolepidae, Spongillidae. In: J. Hooper & R. W. M. van Soest (Eds.), Vol. 1. Systema Porifera. A guide to the classification of sponges. Kluwer Academic / Plenum Publisher: New York, pp. 921 - 1019. http: // dx. doi. org / 10.1007 / 978 - 1 - 4615 - 0747 - 5 _ 97","Manconi, R. & Pronzato, R. (2007) Gemmules as a key structure for the adaptive radiation of freshwater sponges: a morphofunctional and biogeographical study. In: Custodio M. R., Lobo-Hajdu G., Hajdu, E. & Muricy, G. (Eds.), Porifera research: biodiversity, innovation and sustainability. Serie Livros. Museu Nacional: Rio de Janeiro, pp. 61 - 77.","Gee, N. G. (1931 b) Freshwater sponges of the Philippine Islands. The Philippine Journal of Science, 46 (1), 61 - 74."]}

Pectispongilla gagudjuensis n. sp. Manconi & Pronzato Figs 1 b, 6, 7, 8, 9; Tables 1, 2, 4 Material. Type material NTM ZOO 2024, NTM ZOO 2680, NTM ZOO 4338, NTM ZOO 4339, NTM ZOO 4340 from a small unnamed dry creek, 12��43���S 132��46���E (Fig. 1, site b) along the Kakadu Highway, North of Malabanjbanjdju, Kakadu National Park, Alligator River Region, Northern Territory, 11.vii.1998, leg. Luca Pronzato. Some slides and stubs (DTRG-FW568 a, b, c, d, e) are deposited in the authors��� collection. Comparative material. Pectispongilla botryoides NTM Z001405 (DTRG-FW646) and part of the latter as AM Z3504 (DTRG-FW701), Tanami Gorge, 19��58���S 129��39���E, Camel Waterhole, Northern Territory, 25.v.1970, leg. P. Latz, S. Parker & D. Howe, det. A.A. Racek; AM Z2905, Manchester Lake, Queensland, 6.ix.61, det. A.A. Racek (DTRG-FW700). P. aurea var. subspinosa , syntype, BMNH 14.11.24.34 (ex ZEV 3790/7), Kochi (ex- Cochin), Ernakulam, Kerala, SW India (DTRG-FW401); USNM 34578, Penney collection 90124, schizosyntype, dry, Kochi (ex-Cochin), Ernakulam, Kerala, SW India (DTRG-FW553); ZMB 7981 from BMNH 14.11.24.34, alcohol, Kochi (ex-Cochin), Ernakulam, Kerala, SW India (DTRG-FW515). Etymology. The specific epithet refers to the native word Gagudju (from which Kakadu) derived from the name of one of the ca. thirty old native languages of the flood plain area in the Arnhem Land. Diagnosis. Pectispongilla gagudjuensis n. sp. is characterised by two types of short skeletal megascleres (acanthostrongyles and acanthoxeas), absence of microscleres, free gemmules, mature botryoidal gemmuloscleres with disto-lateral apices as irregular concavities grouped to form a botryum, and growth form as a small hollow cup in dry condition. Description. Growth form encrusting as minute almost flat cushions (max. 1 cm in diameter) scattered and strictly adhering to substrata by basal spongin plate. Surface smooth. Consistency hard and fragile. Colour white. Oscul e apical, single, central, large (300���350 ��m in diameter). Ectosomal skeleton compact and dense arrangement of spicules more or less tangential. Choanosomal skeleton vaguely reticulate network of spicules joined by scanty spongin. Spongin scanty except for basal spongin plate and gemmular theca. Megascleres of two types. Dominant acanthostrongyles [90���168 (135��19) x 8���13 (10��4) ��m] almost straight to notably bent (boomerang-like shaped), spiny by few scattered short spines sometimes more dense at the tips. Acanthoxeas (mucronate acanthostrongyles?) [130���205 (163��19) x 5���12 (8.5��1.9) ��m] less frequent, gradually to abruptly pointed, with short spines from scattered to more dense at the tips. Microscleres absent. Gemmules free (up to 8 for each specimen), small (200���350 ��m in diameter), subspherical after rehydration with gemmuloscleres more or less radially embedded. Foramen single with a short tube and a well developed collar. Gemmular theca thick, trilayered. Outer layer with a variable amount of compact spongin, as a honeycomb-like surface due to the partial emergence of distal botryoidal apices of gemmuloscleres. Pneumatic layer as an irregular network of anastomosing thin spongin fibres. Inner layer of sublayered compact spongin. Gemmuloscleres botryoidal (mature) to pseudo-botryoidal (immature) [26���46 (36��4) x 2���3 (2.9��0.29) ��m] with smooth, straight to slightly bent shafts and a range of variable shape at the convex side of each tip according with the age of the spicules. Immature gemmuloscleres with disto-lateral arrangement of simple small spines in rows (pseudo-botryum); botryum-like tips in growing spicules with a progressive increase of siliceous webs joining spines one to each other; true botryoidal tips with a cluster of well developed rounded concavities in more aged gemmuloscleres. Remarks. A comparative analysis of Pectispongilla gagudjuensis n. sp. showed that it matches only in part diagnostic traits of the other species of the genus (Table 4). The skeletal megascleres are shorter than the other species of the genus and the gemmules are the largest of the genus. Microscleres are absent in P. gagudjuensis n. sp., whereas microscleres of P. aurea Annandale, 1909 and P. subspinosa Annandale, 1912 are smooth to microspined oxeas (Penney & Racek 1968, p. 78���79) and those of P. stellifera Annandale, 1915 range from microspined oxeas to subspherical tubercled spherasters (Penney & Racek 1968, p. 79). Compared with the Australian P. botryoides Haswell, (1882) and the other species of the genus the gemmuloscleres of the new species have the shorter shafts. Moreover the gemmuloscleres of P. gagudjuensis are characterized by displaying the entire range of the various tip morphs (Fig. 8) hitherto recorded in the other four species of Pectispongilla i.e. from small spines in rows (immature gemmuloscleres) up to well developed botryoidal-like apices (mature spicules). The peculiar body architecture deeply diverges from Pectispongilla species and all other Spongillida i.e. reduced in dry condition to an almost hollow cup with megascleres to form the body wall and containing only free gemmules and a few spicular tracts. This morpho-functional trait has never been hitherto described for the family Spongillidae and is comparable only to the Baikalian Swartschewskia papyracea (Dybowsky, 1880) in dry condition. This body architecture, closely adhering to the substratum by a thin spongin basal plate, indicates its functional role as a protective device for gemmules during the long, harsh dry season. Its morpho-functional role is comparable to that performed by the gemmular cages of megascleres enveloping the gemmular theca found in other genera of Spongillida. P. gagudjuensis however diverges in the depth of the gemmular cage architecture described for other genera (e.g. Corvospongilla Annandale, 1911; Heterorotula Penney & Racek, 1968; Uruguayella Bonetto & Ezcurra De Drago, 1969; Pachyrotula Volkmer-Ribeiro & R��tzler, 1997). In synthesis, exclusive traits of P. gagudjuensis n. sp. in comparison with those of the other Pectispongilla species are as follows: i) single apical oscular aperture, ii) presence of free gemmules in the hollow internal space of the dry body, iii) megascleres of two types i.e. acanthoxeas and dominant acanthostrongyles, iv) short length of megascleres (ca. half of those of other species), v) largest gemmules of the genus, vi) shorter shafts of gemmuloscleres in the genus (see Annandale 1915 and Penney & Racek 1968). The diagnosis of the genus is here emended adding the presence of spiny strongyles among megascleres. Genus Pectispongilla Habitat. Lotic, temporary creek. Several dry, scattered small specimens under pebbles, cobbles, and boulders, from 1 to 6 per substratum. Sponges were absent from the surveyed horizontal rocky bed and timbers. Encrusting bryozoans, with statoblasts, on the same substrata but not strictly associated to the sponges, were also collected and preserved together with the sponges. Geographic distribution. P. gagudjuensis n. sp. is known only from the type locality. The disjunct Oriental, Australasian, and far east Palaearctic biogeographic pattern of Pectispongilla (5 species) seems to indicate Gondwanan origins and is restricted to the south-western Indian sub-region and Australia with an enclave in Korea and Japan (Annandale 1911, 1915; Penney & Racek 1968; Racek 1969; Manconi & Pronzato 2002, 2007, 2015) (Fig. 9). P. botryoides Haswell, 1882 is reported exclusively from Australia (Tables 1���2). Two species P. aurea Annandale, 1909 and P. stellifera Annandale, 1915 are endemic to restricted areas in the SW-Indian subregion, while P. subspinosa Annandale, 1911 is known from SW-India, Japan, and Korea (Tables 1���2)., Published as part of Manconi, R., Cubeddu, T. & Pronzato, R., 2016, Australian freshwater sponges with a new species of Pectispongilla (Porifera: Demospongiae: Spongillida), pp. 61-76 in Zootaxa 4196 (1) on pages 69-74, DOI: 10.11646/zootaxa.4196.1.3, http://zenodo.org/record/167679, {"references":["Penney, J. T. & Racek, A. A. (1968) Comprehensive revision of a world-wide collection of freshwater sponges (Porifera: Spongillidae). United States National Museum Bulletin, 272, 1 - 184.","Annandale, N. (1915) Notes on freshwater sponges of the genus Pectispongilla and its allies. Records of the Indian Museum, 11, 171 - 178.","Haswell, W. A. (1882) On Australian freshwater sponges. Proceedings of the Linnean Society of North South Wales, 7, 208 - 210.","Annandale, N. (1911) Freshwater sponges, hydroids and polyzoa. Porifera. In: A. E. Shipley (Ed.), Fauna of British India, Including Ceylon and Burma. Taylor & Francis: London, pp. 27 - 126, 241 - 245","Racek, A. A. (1969) The freshwater sponges of Australia (Porifera: Spongillidae). Australian Journal of Marine and Freshwater Research, 20, 267 - 310.","Manconi, R. & Pronzato, R. (2002) Spongillina n. subord. Lubomirskiidae, Malawispongiidae n. fam., Metaniidae, Metschnikowiidae, Palaeospongillidae, Potamolepidae, Spongillidae. In: J. Hooper & R. W. M. van Soest (Eds.), Vol. 1. Systema Porifera. A guide to the classification of sponges. Kluwer Academic / Plenum Publisher: New York, pp. 921 - 1019. http: // dx. doi. org / 10.1007 / 978 - 1 - 4615 - 0747 - 5 _ 97","Manconi, R. & Pronzato, R. (2007) Gemmules as a key structure for the adaptive radiation of freshwater sponges: a morphofunctional and biogeographical study. In: Custodio M. R., Lobo-Hajdu G., Hajdu, E. & Muricy, G. (Eds.), Porifera research: biodiversity, innovation and sustainability. Serie Livros. Museu Nacional: Rio de Janeiro, pp. 61 - 77."]}

Radiospongilla cfr. philippinensis (Annandale, 1909) Figs 1 a, 2, 3, 4, 5; Tables 1, 2, 3 Material examined. Four specimens NTM ZOO 5052, NTM ZOO 5056, NTM ZOO 5063, NTM ZOO 5069. Dry shore of a billabong, Mamukala Wetlands, 12°38’S 132°35’E, 7 km East of the South Alligator River, South off the Arnhem Highway, Kakadu National Park (Fig. 1, site a), 10.vii.1998, R. Manconi leg. Some slides and stubs (DTRG-FW571a, b, c, d) are deposited in the authors’ collection. Additional material. NTM Z001431, Tom Lagoon, NT, 16°22’S 134°50’E, Latz leg., 3.i.1971, large clusters on roots (DTRG-FW706); NTM Z001435, unknown location, Stn n. FW-0016 (DTRG-FW707) Comparative material. Radiospongilla sceptroides, AM Z2837, neotype, Merrika River, Nadgee Faunal Reserve near Womboyne (37°15’S, 149°55’E), New South Wales, Australia, on large rock, 0.5 m depth, 6.iii.1958, leg. F. Hersey, det. Penney & Racek (DTRG-FW542). Spongilla philippinensis, BMNH 34.4.28.1 box 13.III. C, alcohol, leg. L.E. Cheesman, Lake Sentani, Dutch New Guinea (DTRG-FW382). Spongilla sceptroides Haswell, BMNH 86.8. 27.665, box 13.III. C, alcohol, Brisbane, Australia (DTRG-FW387), BMNH 86.8.27.658, box 5, dry, leg. von Lendenfeld, Kakalum River, Australia (DTRG-FW409). Spongilla cerebellata Bowerbank, 1863, schizotype, Bowerbank collection, leg. Brudley, Dominion of Nizam (DTRG- FW412). Description. Growth form encrusting (5–6 mm in diameter, 2–5 mm thick) to cushion-shaped (3.5 cm in diameter, 1 cm thick). Consistency extremely fragile (dry specimens are, at present, completely fragmented due to their extremely fragile consistency). Colour whitish in dry condition. Oscules scattered. Ectosomal skeleton with no special architecture. Choanosomal skeleton irregularly reticulate network, with ascending paucispicular primary fibres and vague secondary tracts. Spongin scanty. Megascleres acanthoxeas of two size classes straight to slightly bent, from stout [232–302 (266±17) x 6–13 (9.28±0.96) µm] to slender [188–226 (208±13) x 2.9–5.8 (5.24±1.06) µm] ornamented by large, straight to curved variably dense small spines except at the tips. Microscleres absent. Gemmules subspherical (600–750 µm in diameter) single to grouped (2–3) scattered in the skeletal network at the sponge basal portion. Foramen in a more or less conical depression, simple, without collar, with brown, slender porus tube. Gemmular theca trilayered with gemmuloscleres in a single layer more or less radially embedded (NTM ZOO 5052, 5056, 5063, 5069) to in double layer both tangentially arranged at theca surface and radially embedded in it (NTM Z001431, NTM Z001435). Outer gemmular surface hispid due to the emerging distal apices of gemmuloscleres. Pneumatic layer with vague chambers of spongin to with welldeveloped polygonal chambers. Inner layer sublayered of compact spongin. Gemmuloscleres [122–174 (148±12) x 2.3–8.7 (5.25±2.26) µm] straight to slightly curved of two types from slender acanthoxeas abruptly pointed with few small scattered spines except at the tips, to stout acanthostrongyles with large straight spines scattered along the axis, and curved spines densely clustered at the tips. Habitat. Several dry sponges were discovered along the shore of an almost dry billabong in shaded areas on the painted metallic piers of a bird-watching platform and on surrounding dry timbers and bushes between the platform and the path (Fig. 2). Data confirm the typical growth mode of this species on natural and artificial substrata (Racek 1969). Geographic distribution. The geographic range of R. philippinensis is from the Philippines to northern Australia (Tables 1–2). The present record in Kakadu National Park confirms the presence of this species in coastal tropical-subtropical areas of the north, western and southern Australia (Racek 1969). On the other hand R. streptasteriformis Stanisic, 1979 is apparently endemic to the Northern Territory (Tables 1–2) (Stanisic 1979) whereas R. pedderensis Osborne, Forteath & Stanisic, 2008 is endemic to Tasmania (Osborne et al. 2008). The doubtful presence in Australia of R. crateriformis (Potts, 1882) is discussed by Racek (1969). The biogeographic pattern of the speciose Radiospongilla (18 species) is in the Australasian, Afrotropical, Neotropical, Nearctic, Oriental, and Palaearctic regions (Fig. 5) (Penney & Racek 1968; Manconi & Pronzato 2002, 2007). Remarks. In his synopsis on Australian freshwater sponges Racek (1969) clarified the taxonomic status of Radiospongilla philippinensis (previously a junior synonym of R. sceptroides) as a valid species (Penney & Racek 1968). On the basis of comparative analysis of specimens from Kakadu National Park bearing gemmules with a single layer of radial gemmuloscleres are here ascribed to R. cfr. philippinensis (Table 3) because they diverge from descriptions of Philippine and other Australian material (Annandale 1909ab). Also additional material from the NTM bearing gemmules with two layers of gemmuloscleres i.e. tangentially and radially arranged in the gemmular theca is here ascribed to R. cfr. philippinensis (Table 3). Radiospongilla Radiospongilla philippinensis cfr. philippinensis Gemmuloscleres acanthostrongyles acanthostrongyles acanthostrongyles acanthostrongyles µm 80–122 x 31 105–180 x 4–5 acanthoxeas acanthoxeas 102–149 x 4.5–7 122–174 x 2.3–8.7 Gemmular tangential spicules in irregularly radial irregularly radial theca single layer spicules in single tangential and radial spicules in spicules in single layer double layer layer References *Annandale 1909ab Racek 1969 Present paper Present paper # Gee, 1931b GENUS Pectispongilla ANNANDALE , 1909

The use of sponges for marine bioremediation in a farming scenario has been investigated focusing on Chondrilla nucula. We report experiments examining clearance and retention rates of the bacterium Escherichia coli. Despite low values expressed for clearance tests, C. nucula exhibited a marked ability to retain high quantities of bacteria. One square meter patch of this sponge can filter up to 14 l/h of sea water retaining up to 70 x/1010 bacterial cells/h. This suggests that C. nucula is a suitable species for marine environmental bioremediation.

The sterols of the freshwater sponges E. fluviatilis and S. lacustris were isolated and characterized by reverse-phase HPLC, silver nitrate-silica gel TLC, mass spectrometry, and 1H NMR. E. fluviatilis and S. lacustris have rather similar sterol compn. and contain almost exclusively Δ5-sterols. Cholesterol is the major sterol. In addn. to the Δ5-sterols, E. fluviatilis contains a small amt. of 24-methyl-5α-cholestan-3β-ol. The C-24 configuration of 24-alkyl sterols was detd. Sterols with the 24β configuration predominate over the 24α epimers. A brief review on uncommon sterols in sponges is also given

1. 1. Δ5,7-sterols have been isolated as pure compounds from the marine sponges Ircinia pipetta (Dictyoceratida:Thorectidae) and Dysidea avara (Dictyoceratida:Dysideidae) by reverse phase HPLC and analyzed by GLC, u.v., mass spectrometry and 1H-NMR. 2. 2. Ircinia pipetta and D. avara have rather similar sterol compositions and contain predominantly Δ5,7-sterols, accompaned by Δ5-sterols. Ergosterol, cholesta-5,7-dien-3β-ol and 24-ethylcholesta-5,7-dien-3β-ol are the major sterols in I. pipetta, while D. avara contains in addition to these three sterols, (24Z)-24-ethylcholesta-5,7,24(28)-trien-3β-ol as the fourth major sterol. 3. 3. Cholesta-5,7,24-trien-3β-ol which previously was not isolated from a marine organism is also present.