Corvospongilla lemuriensis Manconi & Pronzato, 2019

Manconi, Renata & Pronzato, Roberto, 2019, The genus Corvospongilla Annandale, 1911 (Porifera: Demospongiae: Spongillida) from Madagascar freshwater with description of a new species: biogeographic and evolutionary aspects, Zootaxa 4612 (4), pp. 544-554 : 546-550

Corvospongilla lemuriensis Manconi & Pronzato sp. n.

Figs 1–5

Material. Holotype: MSNG 60893 a, dry specimen (schizotype DTRG FW807 ), Farihy Amboromalandi reservoir (Lat. -16.122850, Long: 46.748326), 12 m asl, Betsiboka River hydrographic basin near Ankazomborona village along the Route National 4, North-Western Slope, Madagascar, 9.ix.2016, legit R. Manconi.

Paratypes: MSNG 60893 b, ibid. (schizoparatype DTRG FW806 ) ; MSNG 60893 c, ibid. (schizoparatype DTRG FW805 ) .

Topotypes: DTRG FW802, ibid., DTRG FW804, ibid.

Slides and SEM stubs are preserved in the DTRG author’s collection.

Comparative materials. Corvospongilla becki , USNM topotypes, dry, DTRG FW919, FW920, FW921, Duck Lake, Louisiana, USA; C. burmanica , BMNH 82.3.22.1–3, box 6, dry, type, DTRG FW420 schizotype, Burma; C. burmanica (?), BMNH 86.10.29.1, DTRG FW 636, River Kuano, India; C. caunteri , BMNH 14.11.24.27 ex-ZEV 4776/7, paratype, DTRG FW637 schizotype, Lucknow, India; C. lapidosa , BMNH 08.2.11.1, paratype, DTRG FW638 schizotype, River Godavery Nasik, India; C. loricata , ZMB 2093 SE325-SE37–41, type, DTRG FW511 schizotype, locality unknown, Africa; C. mesopotamica MSNG 51766, holotype, DTRG FW574 schizotype, River Diyala, Iraq; C. siamensis , MSNG 56533, holotype, Ban Huai Sai, Pong River, Thailand; C. thysi , MRAC 1311, type, DTRG-FW 472 schizotype, Lake Barombi-ma-Mbu, Cameroun, W-Africa; C. ultima , BMNH 14.11.24.29 ex- ZEV 4906/7, DTRG FW639, fragment, India; C. ultima var. spinosa , BMNH 14.11.24.30 ex-ZEV 5106/7, DTRG- FW640, Satara District, India; C. seckti (as C. volkmeri ) BMNH 89.9.25.10, schizoparatype, ex-MCN 86, DTRG FW642, Lagoa Redonda, Sousa, Paraíba State, Brazil; C. zambesiana , BMNH 1906.2.28.2, 13 IIIC, DTRG FW623, R. Zambezi, SE-Africa.

Etymology. The specific epithet lemuriensis refers to the hypothetical former continent Lemuria in the Indian Ocean.

Diagnosis. Corvospongilla with gemmules of a single morph i.e. sessile with conspicuous chambered pneumatic layer in the tri-layered gemmular theca within a stout spicular cage; acanthostrongyles (dominant), and acanthoxeas to acanthostrongyloxeas as skeletal megascleres; acanthostrongyles, and acanthoxeas to acanthostrongyloxeas as gemmuloscleres.

Description. Growth form encrusting, very thin (ca 1 mm) with undulated surface due to the presence of scattered gemmular carpets. Colour light brown to reddish for the presence of trapped red dust. Consistency hard, fragile in dry condition. Spongin scanty in the skeleton, conspicuous in the basal spongin plate and in the gemmular theca. Basal spongin plate notably developed, densely armed by tangential spicules around gemmules. Surface regular, smooth. Oscules few, scattered, small. Ectosomal and choanosomal skeleton very thin (ca 1 mm in thickness), alveolate (isotropic) network of megascleres with polygonal meshes and rare, short pauci-spicular tracts (1–4 spicules) of strongyles and scanty spongin; a few, scattered oxeas also present. Spicules sometimes malformed. Megascleres dominant acanthostrongyles (107–163 x 12–14 µm; n = 25) to acanthoxeas-acanthostrongyloxeas (127–186 x 9 µm; n = 25) densely spiny by small spines. Microscleres very few, scattered in the skeleton and near gemmular carpets; micropseudobirotules (8– 38 x 5–10 µm; n = 15) with thin, slightly curved to straight shaft entirely smooth, and variable length; pseudorotules (10–15 µm in diameter; n = 15) entirely smooth, armed by up to 3–9 hooks with long, acute tips. Gemmules light brown in colour, exclusively sessile, strictly adhering to the basal spongin plate sharing gemmular cages with fused walls, and grouped in large to small groups. Free gemmules not found. Gemmular cage grey-brownish in colour, hemispherical (450 x 790 µm in diameter; n = 10), stout, armed by a dense multilayer of spicules from irregularly (outer) to mosaic-like (inner) arranged of variably long acanthostrongyles (20–160 µm, n = 30) resembling skeletal megascleres and gemmuloscleres; very rare, stout, oxeas (93–139 µm, n = 2) sometimes with a few large spines at tips also present. Cage easily detachable from the surface of the gemmular theca. Gemmular theca tri-layered, subspherical (280–700 µm in diameter; n = 25). Outer layer of almost compact spongin with small concavities and bubbles (resembling chambers of the underlying pneuma) at the irregular surface armed by variably dense gemmuloscleres tangentially arranged. Pneumatic layer (19–40 µm in thickness, DTRG FW804) of chambered spongin with rounded chambers of variable size; mono- to multi-layers of gemmuloscleres (finely spiny strongyles to oxeas with large spines) tangentially embedded in the chambered spongin at various depths. Inner layer with 3-4 sublayers of compact spongin sometime in contact with tangential gemmuloscleres. Foramen single with short simple collar, aperture oriented upward in gemmular carpets. Gemmuloscleres from strongyles with small, dense, simple spines to oxeas-strongyloxeas spiny more densely at the tips (19 – 84 x 7–14 µm, n = 40) straight or curved to less frequently U-like and ring-like.

Habitat. Lentic small water body (reservoir) with brown-reddish water near the Ankazomborona village along Route Nationale 4 at an altitude ca 12 m asl. The area is characterised by the Tropical Savanna Climate ( Köppen 1936; Köppen & Geiger 1954; Peel et al. 2007). Sponges, found along the coastal line of the reservoir periodically subjected to the dry up, were settled in the variably shaded areas on boulders surfaces exposed to air or submerged in shallow water. Sponges were associated with diatoms, and larvae/pupae of insects.

Life cycle. Sponges were dormant during the low water level phase at the end of the dry season (September); with abundant gemmules ( Fig. 1 D, E ), they were in the aestivant phase and able to survive long term exposition to strong sun radiation and hot air. Some gemmules hatched, after rehydration, over a year later, in our labs.

Geographic range. The extent of its geographic range is unknown. Currently recorded exclusively from the type locality in the small reservoir Farihy Amboromalandi near the Ankazomborona village along the Betsiboka River hydrographic basin, tributary of the Mozambique Channel in the north-western slope of Madagascar.

Figures

FIGURE 1. Corvospongilla lemuriensis sp. n. Type locality along the Betsiboka River hydrographic basin of North-western Madagascar in the climatic areas map sensu Köppen-Geiger. A Amboromalandy Lake (reservoir; b/w dot) in tropical savanna; A’ Type locality (b/w dot) in the Betsiboka River hydrographic basin; B Amboromalandy Lake during low water level season (September 2016) harbouring sponges settled on the boulders of the dam; C Satellite image and road map of the Amboromalandy Lake type locality (colour dots); D-E Sponge with encrusting growth form (D) with large patches of gemmules armed by spicular cage (E) on a boulder of the dam in dry condition during the arid season.

FIGURE 2. Spicular complement of Corvospongilla lemuriensis sp. n. (LM and SEM micrographs specimen DTRG FW804). Aa Spiny strongyles as dominant megascleres; Ab Spiny oxeas to strongyloxeas as less frequent megascleres; B Spiny strongyles, oxeas to strongyloxeas as gemmuloscleres; Ca Megasclere; Cb Gemmuloscleres. For topographic distribution of spicules and other details on microtraits see also Figure 4.

FIGURE 3. Corvospongilla lemuriensis sp. n. (SEM micrographs). Micropseudobirotules (microscleres). a Specimen DTRG FW804; b Specimen DTRG FW805.

FIGURE 4. Gemmules of Corvospongilla lemuriensis sp. n. (SEM micrographs). A Gemmular cage shared by gemmules (top view) and armed by spicules (megascleres) in a dense mosaic-like layer bearing two foraminal collars; B Cage enveloping the gemmule (cross section) with megascleres and gemmuloscleres; C Gemmular theca surface with gemmuloscleres emerging at the surface (foramen not evident); D Gemmular theca surface with various morpha of megascleres and gemmuloscleres; E Micropseudobirotules (skeletal microscleres) at the gemmular surface; F Gemmular theca (cross section) tri-layered with inner layer of compact laminar spongin surrounding staminal cells, inconspicuous outer layer, and thick pneumatic layer with gemmuloscleres tangentially embedded in chambered spongin. A, B, D = specimen DTRG FW806; C = specimen DTRG FW807; E, F = specimen DTRG FW804.

FIGURE 5. Biogeographic pattern of the genus Corvospongilla at global level with 19 species. The majority of species are recorded in the Afrotropical Bioregion and the Indian Subregion. The type locality of Corvospongilla lemuriensis sp. n. at Amboromalandy Lake in North-western Madagascar (Lat. -16.122850, Long. 46.748326; Betsiboka River basin) is indicated by a red dot.