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