Radiospongilla sceptroides (Haswell, 1882)

Ruengsawang, Nisit, Sangpradub, Narumon, Cubeddu, Tiziana, Erpenbeck, Dirk, Wörheide, Gert, Pronzato, Roberto & Manconi, Renata, 2025, Bangkok urban census of aquatic invertebrate fauna by an integrative taxonomic approach: the case of Suan Luang Rama IX Park and its freshwater sponges (Spongillida: Spongillidae), Zootaxa 5660 (3), pp. 371-388 : 377

Radiospongilla sceptroides (Haswell, 1882)

AUSTRALIA — New South Wales, Merrika River, Nadgee Faunal Reserve near Womboyne ; 37°15′ S, 149°55′ E; 6 Mar. 1958; F. Hersey leg.; Penney & Racek det.; AM Z2837 , neotype (schizotype RM & RP-FWPOR 542 ) .— Kekelum River ; von Lendenfeld det.; BMNH 86.8 . 27.658, box 5 (fragment RM & RP-FWPOR 409 ).— Brisbane; alcohol; BMNH 86.8 . 27.665, box 13.III.C (fragment RM & RP-FWPOR 387 ) .

Description

Growth form encrusting, very thin (3–6 x 8–13 cm in diameter, ~ 0.5 cm in thickness) on submerged terracotta and plastic pots ( Figure 2). Colour emerald green to light green in vivo with evident light brown gemmules ( Figure 2). Consistency firm and fragile in vivo. Oscules inconspicuous in vivo along well developed, not-branched, parallel subdermal canals ( Figure 2). Surface slightly hispidate by tips of ascending skeletal spicular fibres ( Figure 3). Ectosomal skeleton as few, scattered, tangential, short ornate spicules in the dermal membrane. Choanosomal skeleton as anisotropic reticulate network, paucispicular fibres/tracts with scanty spongin ( Figure 3). Spongin well developed at the level of gemmular theca and basal spongin plate and scanty in skeletal network ( Figure 7). Basal spongin plate well developed, armed by megascleres, and with only partly adhering gemmules ( Figure 3). Megascleres smooth, long oxeas (252–316 x 7–11 µm, n = 50) slightly curved with tapered tips. Less frequent stout, smooth, long oxeas slightly curved with abruptly pointed tips. Spicular tips sometimes tapered and blunt/abruptly pointed in the same oxea. Slender, smooth oxeas also present (182–187 x 4 µm, n = 2). Rare very short slim oxeas probably larval. Malformations rarely present as angulate tips ( Figure 4). Spicules very similar to gemmuloscleres tangential in the dermal membrane as few, scattered, short, spiny strongyles to strongyloxeas could be related to gemmuloscleres dislocation due to the very thin thickness of sponge body. Gemmular cage of megascleres apparently absent. Gemmules subspherical (352–541 µm in diameter), abundant, in large to small variably dense groups/carpets, variably adhering to the basal spongin plate ( Figures 2–3). Foramen rarely evident, rounded with simple collar, sometimes with undulate margins ( Figure 3). Gemmular theca trilayered and armed by two layers of gemmuloscleres, i. irregularly tangential, variably oriented and embedded in the outer layer of theca, and ii. radially embedded at low density in the pneumatic layer ( Figure 6). Outer layer with honeycombed ornamentations ( Figure 7) under the strongly armed layer of variably oriented tangential gemmuloscleres ( Figure 6). Pneumatic layer thick (75–115 µm in thickness) armed by scattered, not abundant, irregularly radial gemmuloscleres; pneuma variably arranged in the same theca as (a) polygonally chambered only towards the outer layer, (b) extensively lamellar (dominant) to (c) network of thin anastomosed filaments mostly developed towards the inner layer ( Figure 7). Inner layer multilayered of compact spongin as laminae lining the smooth central cavity containing totipotent/staminal cells i.e., thesocytes ( Figures 6–7). Gemmuloscleres straight to slightly bent dominant acanthostrongyles (blunt tips) and rare acanthostrongyloxeas (relatively acute tips) (81–106 x 3–6 µm, n = 50) entirely ornamented by spines and hooks. Small spines scattered along the shaft and densely grouped hooks towards tips. Hooks, stout, long, bent sometimes bearing one to few microspines. Spines single, large with narrow basis, ranging from simple to mostly armed by short, large microspines (n = 2–5) grouped at tips ( Figure 5). Rare gemmuloscleres with only a few large spines also present.