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 : 377-380

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.

Habitat and ecology

Only found in lentic, small very shallow water (5–30 cm depth), as thin green sponges with encrusting habitus and dense carpets of gemmules (in January and March) on submerged hard, man-made substrata e.g., black plastic vases and brown pottery vases ( Figure 2 ). Sponges were not found, until now, on hard natural substrata e.g., plants, wood, and stones/rocks. Diatoms frustules, nymph of Hemiptera ( Figure 6 ), and larvae of dipterans were found associated with sponges.

Geographic distribution

Only known, until now, from Suan Luang Rama IX Park, Bangkok, Thailand.

Results of molecular analyses

ITS 1 and 2 (including partial flanking 28S and 18S and the separating 5.8S rDNA of Radiospongilla cf. cerebellata from Bangkok CNR-POR-FW 310-312 could successfully be amplified.

These sequences were aligned with ITS of all other Radiospongilla species published i.e. R. crateriformis from Japan (International Nucleotide Sequence Databases number EF151952 ), R. sendai from Japan (INSD: EF151954 ), R. cerebellata from Japan (INSD: EF151938 ), furthermore R. fungosa from Australia WAM Z98300 ( Itskovich et al. 2008; Maikova et al. 2010; Pronzato & Manconi 2020). The initial MAFFT alignment comprised 748 characters, after pruning with Gblocks 501 positions remained. The maximum likelihood tree recovers a monophyletic and well-supported R. cerebellata & R. cf. cerebellata clade ( Figure 8 ). Differences between R. cerebellata and R. cf. cerebellata were too low (3 bp before pruning) to result in supported monophyletic R. cf. cerebellata . Sister to R. (cf.) cerebellata is R. crateriformis , while R. fungosa branches first from all Radiospongilla species in this analysis.

Figures

FIGURE 2. Radiospongilla cf. cerebellata from fragmented freshwater lentic habitats at the Suan Luang Rama IX Royal Botanical Garden of Bangkok. In vivo sponge specimen series with gemmule-bearing encrusting growth form on submerged pots harbouring with various plants. A. Greenhouse (site 6). B. Pond of tropical greenhouse (site 6) inhabited by specimen CNR-POR-FW 311 (see F) and specimen CNR-POR-FW 310 (see G). C. Lotus and Waterlily Garden with large, mobile pots scattered in the garden (site 7). D. Submerged plastic pot encrusted by sponges (within a terracotta pot). E. Irregular growth form of specimen CNR-POR-FW 312 on a plastic pot (site 7). F. Specimen CNR-POR-FW 311 bearing gemmules on terracotta pot in the greenhouse. G. Specimen CNR-POR-FW 310 on a submerged plastic pot in the greenhouse. (Sites numbers refer to those inhabited by sponges in the Botanical Garden map of Figure 1B.

FIGURE 3. Radiospongilla cf. cerebellata specimen CNR-POR-FW 311 (B–H) and specimen CNR-POR-FW 312 (A) from Suan Luang Rama IX Royal Botanical Garden of Bangkok by Scanning Electron Microscopy. A–B. Skeletal fragments with paucispicular tracts of smooth oxeas (megascleres). C–D. Gemmules associated to skeletal network. E. Gemmular theca’s surface armed by densely arranged tangential gemmuloscleres with fragments of basal spongin plate. F. Laminar fragment of basal spongin plate (for substrate adhesion, asterisk) on tangential gemmuloscleres at the theca surface (detail of E). G. Foramen simple with laminar collar (arrow) surrounded by gemmuloscleres at theca surface. H. Honeycombed ornamentations (arrow) at theca’s outer layer level underlying the tangential layer of gemmuloscleres.

FIGURE 4. Radiospongilla cf. cerebellata specimen CNR-POR-FW 311 (D) and specimen CNR-POR-FW 310 (A, C), CNR- POR-FW 312 (B, E–F) from Suan Luang Rama IX Royal Botanical Garden of Bangkok. Spicular complement of skeleton and gemmules by Light Microscopy. A–D. Oxeas smooth as skeletal megascleres with some spiny gemmuloscleres. E–F. Gemmuloscleres spiny strongyles to strongyloxeas with spines along the axis and hooks towards the tips.

FIGURE 5. Radiospongilla cf. cerebellata from Suan Luang Rama IX Royal Botanical Garden of Bangkok. Specimen CNR- POR-FW 311 (A, C–J) and specimen CNR-POR-FW 312 (B). Spicular complement of skeletal network and gemmules by Scanning Electron Microscopy. A–B. Skeletal megascleres as smooth oxeas and short gemmuloscleres (asterisks indicate strongyloxeas) with ornamented surface. C–E. Gemmuloscleres spiny strongyles (dominant) to rare strongyloxeas, ornamented by large spines with microspines (rosettes) along the central axis and hooks towards the tips. F–J. Strongyles tips with dense ornamentations by variably curved hooks.

FIGURE 6. Radiospongilla cf. cerebellata specimen CNR-POR-FW 312 (A–E) from Suan Luang Rama IX Royal Botanical Garden of Bangkok by Scanning Electron Microscopy. A, D–E. Gemmular theca armed by tangential and radial gemmuloscleres embedded in pneumatic layer, and multilayered inner layer surrounding stem cells (detail of cross section). B–C. Nymph of Hemiptera and diatom (white arrow) associated with sponges.

FIGURE 7. Radiospongilla cf. cerebellata from Suan Luang Rama IX Royal Botanical Garden of Bangkok. Specimen CNR- POR-FW 311 (A, B, E, G) and specimen CNR-POR-FW 310 (C, F). Gemmular theca architecture by Scanning Electron Microscopy and schematic drawings (cross section). Gemmuloscleres as strongyles/strongyloxeas with spines and hooks. A, C. Gemmules armed by two spicular layers, tangential gemmuloscleres at theca surface (outer layer) and variably radial, not dense gemmuloscleres embedded in the laminar pneumatic layer as thin laminae irregularly arranged (detail of cross section, arrow). B. Top view of outer layer with tangential gemmuloscleres (arrow). D. Schema of spatial arrangement of gemmuloscleres. E, G. Irregular filamentous network of pneumatic layer towards the multilaminar inner layer (arrow). F. Honeycombed surface (arrowhead) of outer layer and pneumatic layer with polygonal chambers (arrow). H. Schema of filamentous, fibrous, chambered network spatial arrangement of pneumatic layer.

FIGURE 8. Maximum-likelihood ITS-phylogram displaying the phylogenetic position of Radiospongilla cf. cerebellata (bold) in respect to other Radiospongilla. Numbers on branches are bootstrap support values>50, numbers following taxon names are INSD accession numbers or collection codes. Scale bar are substitutions per site.