Corvospongilla lampaoensis Ruengsawang & Manconi, 2024

Ruengsawang, Nisit, Sangpradub, Narumon, Cubeddu, Tiziana, Pronzato, Roberto & Manconi, Renata, 2024, Biodiversity assessment of the Lower Mekong Basin: evolutionary novelties in gemmular morphotraits of Genus Corvospongilla (Porifera: Spongillida) with description of a new species from Khorat Plateau, and biogeographic notes, Zootaxa 5529 (1), pp. 144-158 : 146-148

Corvospongilla lampaoensis Ruengsawang & Manconi sp. nov.

urn:lsid:zoobank.org:act:0682FDF8-7972-43B8-B42D-F1AE3989CEF0

Figures 1–6

Materials. Holotype CNR-POR-FW 120, 14.vi.2018, leg. N. Ruengsawang, type locality near Thepsuda Bridge (16°42’42.1”N, 103°27’00.6”E) of Lam Pao Reservoir , Lower Mekong Basin , 163 m above sea level (asl), Nong Bua, Nong Kung Si District, Kalasin Province, Thailand . Paratype CNR-POR-FW 121-12, dry specimen, ibidem, 14.vi.2018, leg. N. Ruengsawang. Specimens, slides and SEM stubs are preserved in Collection Nisit Ruengsawang (CNR-POR-FW), Bangkok. For topotypes collected in November 2023 and January 2024 the registration CNR-POR-FW is in progress .

Comparative materials. Genus Corvospongilla , 15 species. C. becki Poirrier, 1978 , USNM dry topotypes, RM & RP-FWPOR 919, 920, 921, Duck Lake, Louisiana, USA; C. burmanica ( Kirkpatrick, 1908) , BMNH 82.3.22.1–3, box 6, dry, type, RM & RP-FWPOR 420 schizotype, Myanmar; C. burmanica (?), BMNH 86.10.29.1, RM & RP-FWPOR 636, River Kuano, NE India; C. caunteri Annandale, 1911 , BMNH 14.11.24.27 ex-ZEV 4776/ 7 paratype, RM & RP-FWPOR 637 schizotype, Lucknow, NE India; C. lapidosa ( Annandale, 1908) , BMNH 08.2.11. 1 paratype, RM & RP-FWPOR 638 schizotype, River Godavery Nasik, S-India; C. lemuriensis Manconi & Pronzato, 2019 MSNG 60893a holotype, RM & RP-FWPOR 807 schizoholotype, RM & RP-FWPOR 804 topotype, Farihy Amboromalandi Reservoir,NW Madagascar; C.loricata ( Weltner, 1895) , ZMB 2093 SE325-SE37– 41 type, RM & RP-FWPOR 511 schizotype, locality unknown, Africa; C. mesopotamica Manconi & Pronzato, 2004 , MSNG 51766 holotype, RM & RP-FWPOR 574 schizotype, River Diyala, NE Iraq; C. moochalabrensis Manconi & Erpenbeck, 2021 , WAM Z29235 holotype, RM & RP-FWPOR 853 schizotype, Moochalabra Dam, NW Australia; C. siamensis Ruengsawang and Manconi, 2012 , MSNG 56533 holotype, Ban Huai Sai, Pong River, Mekong Basin, NE Thailand; C. thysi ( Brien, 1968) , MRAC 1311 type, RM & RP-FWPOR 472 schizotype, Lake Barombi-ma-Mbu, Cameroun, W-Africa; C. ultima Annandale (1910) , BMNH 14.11.24.29 ex-ZEV 4906/7, RM & RP-FWPOR 639 fragment, SIndia; C. ultima var. spinosa, BMNH 14.11.24.30 ex-ZEV 5106/7, RM & RP-FWPOR 640, Satara District, SE-India; C. zambesiana ( Kirkpatrick, 1906) , BMNH 1906.2.28. 2, 13 IIIC, RM & RP-FWPOR 623 (exDTRG), River Zambezi, E Africa; Palaeocorvospongilla cretacea Pronzato, Manconi and Samant, 2021 PGDG / BGVN /1/18,2/18,3/18,4/18, Upper Cretaceous (Maastrichtian), Deccan, Central India.

Diagnosis. Megascleres exclusively spiny oxeas in skeletal network and gemmular cage. Gemmuloscleres spiny to tubercled strongyles and strongyloxeas. Gemmular theca sessile. Outer layer scantly developed and strongly armed by multilayered gemmuloscleres to quite developed and armed by few gemmuloscleres. Pneumatic layer thin, continuous with dense, minute rounded chambers and few gemmuloscleres, or as scantly chambered patches among dense multilayered gemmuloscleres, to not chambered pneuma as thin scattered laminae lining the upper portion of theca. Inner layer ranging, in the same theca, from well developed, smooth, compact, lining the basal part of theca to thin, scattered, small laminae irregularly arranged directly adhering to gemmuloscleres layer inner surface at theca’s middle-upper portion.

Description

Growth form encrusting, irregular (~4.5 x 8.5 cm in diameter, ~ 0.7 cm in thickness). Colour brown to light brown in dry condition ( Figure 2 ) and green-brownish in vivo. Consistency hard, fragile in dry condition. Oscules inconspicuous in dry specimens. Surface densely to irregular and slightly hispidate ( Figure 3 ). Ectosomal skeleton hispid with no special architecture supporting the dermal membrane. Choanosomal skeleton as loose isotropic to anisotropic reticulate network of rounded to polygonal meshes, paucispicular to multispicular fibres/tracts with scanty spongin, and ill-defined, irregular skeletal network towards the basal portion ( Figure 3 ). Spongin scanty in skeletal network and well developed at the level of gemmular theca and basal spongin plate ( Figures 3 , 5 , 6 ). Basal spongin plate armed by megasclere oxeas loosely arranged. Megascleres dominant acanthoxeas (137.6– 160.1 x 7.3–11.5 m, n = 50), slightly curved with abruptly pointed tips and variably dense microspines. Styles and malformations rarely present. Rare slender, spiny oxeas with larger spines probably belonging to larvae ( Figures 3 E-F). Microscleres few, scattered in the skeletal meshwork, variably curved micropseudobirotules (14.7–30.4 x 0.9–1.5 µm, n = 50) with thin smooth shaft bearing smooth pseudorotules at tips (4–9 µm in diameter) with 4–6 long, smooth recurved hooks ( Figures 3F , 4 ). Gemmular cage as scattered not abundant acanthoxeas megascleres ( Figure 5F ) with irregularly distributed small spines (87.5–153 x 6.5–10 µm, n = 11) diverging for outline and spines from skeletal megascleres, and long acanthostrongyles with tubercles (67–88.5 x 7.8–12.2 µm, n = 4). Gemmules hemispherical variably flattened at the lower portion to subspherical (400–800 µm in diameter); abundant, sessile in large to small dense groups, variably adhering to the basal spongin plate, and sometimes partly sharing the gemmular thecas/cages ( Figures 3 , 5 , 6 ). Foramen rarely evident, rounded with simple collar and a short porous tube. Gemmular theca bilayered to trilayered with tangential gemmuloscleres variably embedded and oriented and with layers variably developed and spatially arranged ( Figures 5 , 6 ). Outer layer from strongly armed by gemmuloscleres multilayers to scantly armed by few gemmuloscleres ( Figures 5 , 6 ). Pneumatic layer of dense, minute rounded chambers ranging (also in the same theca) from thin and continuous to as small patches in-between gemmuloscleres, or scantly developed to almost absent ( Figure 6 ). Inner layer ranging (also in the same theca) from scattered trabeculae to compact smooth laminae, to multilayered laminae with smooth surface lining the basal part of theca and partly as thin, small trabeculae directly adhering to gemmuloscleres at the middle-upper part of theca ( Figure 6 ). Gemmuloscleres frequently curved (~158°) acanthostrongyles (blunt tips) and acanthostrongyloxeas (acute tips) with ornamentations as small tubercles/spines, irregularly scattered, grouped or singly, along the shaft and denser at tips ( Figures 5 , 6 ). Dominant acanthostrongyles (56–104 x 8.5–12 µm, n = 50), less abundant acanthostrongyloxeas (80.5–113 x 7.5–11.5 µm, n = 50). Rare acanthoxeas (92–119 x 7–10 µm, n = 11) frequently curved (~162°). Malformations frequently present.

Etymology. The specific epithet lampaoensis is derived from the Lam Pao Reservoir, where Corvospongilla lampaoensis sp. nov. was discovered near the Thepsuda Bridge (type locality). Gender feminine.

Habitat and ecology. The population of Corvospongilla lampaoensis sp. nov. near the Thepsuda Bridge is dominant in lentic, brown, eutrophic shallow water, as large patches with encrusting habitus of variable thickness on hard manmade substrata e.g., fish traps and fish farming (Tilapia) cages structures i.e., plastic buoy, nylon rope, netting, rubble tire ( Figure 2 ). Sponges were not found, until now, on the rare hard natural substrata along the coastline. The site is characterised by notable seasonal variations of water level as also suggested by the persistent presence of abundant gemmules during sampling replicas. Rafts for fish cage culture are seasonally managed and moved within the basin by fishermen according to the weather and water level variations ( Figure 2 ). Aquatic insects, bryozoans, diatoms, and testate thecamoebae were found associated with sponges. Other sponges, with different growth forms, colour and spiculation, were also collected from the Thepsuda Bridge and from the other three sampling sites along the Lam Pao reservoir coastline (identification in progress).

Geographic distribution. Corvospongilla lampaoensis sp. nov. is only known, until now, from the type locality near Thepsuda Bridge (16°42’42.1”N, 103°27’00.6”E), Lam Pao Reservoir , Korat Plateau , Kalasin Province, NE Thailand ( Figure 1 ). The species is endemic to the Mekong Basin, although more sampling effort is required to verify its geographic range also in other Indochina’s hydrographic basins.

Figures

FIGURE 1. A, Map of the Lower Mekong hydrographic basin showing the major tributaries in Khorat Plateau, northeast Thailand. Study area of freshwater sponges (Spongillida) at the Lam Pao Reservoir, (Lam Pao River basin), indicated by a red dashed line square. B, Four sampling sites (red) at the Lam Pao Reservoir 1) Na Chueak (Yang Talat District), 2) Lam Pao (Mueang Kalasin District), 3) Phu Din (Mueang Kalasin District), and 4) Lam Pao near Thepsuda Bridge (Nong Bua, Nong Kung Si District). C, Type locality of Corvospongilla lampaoensis sp. nov. near Thepsuda Bridge, site 4 (16°42’42.1”N, 103°27’00.6”E) Lam Pao Reservoir, 163 m asl, Nong Bua, Nong Kung Si District, Kalasin Province, Thailand.

FIGURE 2. Habitat of Corvospongilla lampaoensis sp. nov. (Spongillida) from the Lower Mekong Basin at Lam Pao Thepsuda Bridge site 4 (Figure 1) type locality, in the Lam Pao Reservoir (Kalasin Province, Thailand).A–B, Manmade substrata on rafts for fish cage culture. C, Encrusting habitus in dry condition of CNR–POR–FW 120 holotype in situ on a plastic buoy (black dashed line square, Figure 2C) after sampling of a part (see also Figure 3A–B), and paratype CNR-POR-FW 121-12 (black asterisk) on a rubber tire.

FIGURE 3. Corvospongilla lampaoensis sp. nov. (Spongillida) holotype CNR-POR-FW 120 from Thailand. SEM micrographs (C–F). A, Dry encrusting thin specimen (top view). B, Dry encrusting thin specimen with sessile gemmules at the level of basal spongin plate (bottom view). C, Skeletal meshwork of acanthoxeas megascleres. D, Skeletal meshwork of acanthoxeas megascleres (top view). E, Acanthoxeas megascleres with microspiny surface except at abruptly pointed tips. F, Acanthoxeas megascleres, pseudobirotules microscleres (arrows) and probable larval spicule (asterisk).

FIGURE 4. Corvospongilla lampaoensis sp. nov. (Spongillida) holotype CNR–POR–FW 120 from Thailand. A, Light Microscopy micrographs. Skeletal microscleres pseudobirotules with smooth, thin shaft and pseudorotules as curved hooks at tips. B, Scanning Electron Micrographs of microscleres.

FIGURE 5. Corvospongilla lampaoensis sp. nov. (Spongillida) holotype CNR-POR-FW 120 from Thailand. Scanning Electron Micrographs. A, Gemmules strongly armed by spicules grouped in a carpet. B, Gemmuloscleres in a dense mosaic-like arrangement at gemmular surface (detail of A). C, Gemmuloscleres acanthostrongyles and acanthostrongyloxeas with variably dense small tubercles and spines. D,Aberrant acanthostrongyles. E, Details of gemmuloscleres ornamentations and tips outlines. F, Megascleres acanthoxeas at the level of scantly developed gemmular cage mixed with gemmuloscleres. Acanthoxeas with scattered, small, conical spines except for tips (diverging from abruptly pointed tips of skeletal acanthoxeas).

FIGURE 6. Corvospongilla lampaoensis sp. nov. (Spongillida) holotype CNR-POR-FW 120 from Thailand. Scanning Electron Micrographs. Gemmular theca architecture of sessile gemmules adhering to basal spongin plate. A, Entire gemmule with few, scattered megascleres (top view). B, Sessile gemmule with scattered thin laminae lining upper portion of theca (white arrow) and smooth, compact inner layer (white arrowhead) and chambered pneumatic layer in basal portion of theca (inner view, cross section). C, Entire sessile gemmule with fragments of basal spongin plate (arrow). D, Gemmular theca (white arrowhead) armed by gemmuloscleres in variably oriented multilayers and scantly developed outer layer and pneumatic layer (cross section); thecamoebae (white arrow). E, Outer layer as a thin pellicle covering spicules (white arrowhead), pneumatic layer absent and inner layer scantly developed (white arrow) in a strongly armed gemmular theca (cross section). F, Pneumatic layer scattered among gemmuloscleres (right) and smooth, compact inner layer of gemmular theca (white arrowhead, cross section). G, Pneumatic layer thin and continuous with dense, minute rounded chambers among few gemmuloscleres in gemmular theca with well-developed outer layer (white arrow, cross section).