Potamolepis bhangazi, Pinheiro & Calheira & Martins & Janson & Taylor & Samaai, 2020

Pinheiro, Ulisses, Calheira, Ludimila, Martins, Celina, Janson, Liesl, Taylor, Ricky & Samaai, Toufiek, 2020, Two new species of freshwater sponges from Neotropical and Afrotropical Regions, Zootaxa 4728 (3), pp. 363-371 : 365-366

Potamolepis bhangazi sp. nov. Pinheiro, Calheira & Samaai

( Fig. 2 ; Table 1 )

Material examined. Holotype. SAMC-A 091310 (cross reference TS3357), Lake Bhangazi-North (27.65397°S, 32.61852°E), a large freshwater lake 20 km south of Sodwana Bay, KwaZulu-Natal, South Africa, coll. Ricky Tailor, 24/09/2013, depth 1–2 m.

Etymology. Named after the type location, Lake Bhangazi-North, an endorheic freshwater lake 20 km south of Sodwana Bay, KwaZulu-Natal, South Africa.

Type locality. Lake Bhangazi-North , Sodwana Bay, KwaZulu-Natal, South Africa .

Type locality description. Lake Bhangazi-North is an endorheic coastal lake with very high water clarity. The water has no suspended sediment but has a slight brown stain. The collection site is at the extreme end of the western arm of the lake - a site protected from wind stirring. It is fed entirely by rainfall and local groundwater inflows. No rivers enter the lake. The whole of the area in which the lake occurs is a large aquifer in recent aeolian sands. The water entering the lake is dystrophic. The lake and its surrounds are pristine - with nobody living within several kilometers from it - and hence inflowing water is likely to be clear of pollution or raised nutrient levels. The lake has a rich growth of fringing vegetation - both on the shoreline and as emergent plants. In the arm where the sponge was found there are patches of submerged water plants growing to a depth of over 2 m. The lake water level seems to be constant - never changing rapidly.

Diagnosis. Potamolepidae encrusting with hispid surface. Megascleres smooth mucronated strongyles. Microscleres smooth oxeas. Gemmules absent.

Description. Encrusting, about 2 to 3 cm long with surface smooth, hispid, oscules inconspicuous. Consistency spongy, soft and fragile. Colour in situ unknown; brown beige when preserved in ethanol ( Fig. 2.A ).

Skeleton. Ectosomal skeleton not observed. Choanosomal skeleton is an anisotropic paucispicular reticulation. Spongin scarce ( Fig. 2.B ).

Spicules. Megascleres. Strongyles, smooth, straight to slightly curved, mucronated, 261–332.2–386 / 19–25– 29 μm ( Fig. 2.C ). Microscleres. Oxeas, smooth, straight, 138–161.5–200 / 6–7.1–10 μm ( Fig. 2.D ). Gemmules and gemmuloscleres absent ( Table 1 ).

Substratum, ecology and depth range. The sponge was found growing attached on the stem of a submerged water plant (macrophyte) ( Potamogeton sp.). Only one specimen was seen, growing just beyond the outer margin of the emergent plant zone. Water in the lake very clear, but sometimes there is a brown stain. Lake protected from the wind and hence not much exposed to wave action. Collected at a depth between 1– 2 m.

Remarks. Potamolepis bhangazi sp. nov. has smooth strongyles as megascleres, usually mucronate, and smooth microsclere oxeas, while P. leubnitziae have no microscleres. Potamolepis belingana , P. chartaria , P. marshalli , P. micropora , P. pechueli and P. weltneri share similar megascleres and microscleres with the new species. However, P. belingana , P. marshalli , P. micropora and P. pechueli have acanthoxea microscleres compared to the presence of microscleres strongyles in the new species. Based on a number of spicular congruencies, P. chartaria is most similar to P. bhangazi sp. nov. Potamolepis chartaria however, have either smooth or spiny strongyle megascleres with inflated tips; in contrast to the tips found in P. bhangazi sp. nov., which is mucronate and always smooth. Furthermore, P. bhangazi sp. nov. has larger microscleres than those found in P. chartaria .

Figures

FIGURE 2. Holotype of Potamolepis bhangazi sp. nov. A, sponge on macrophyte. B, Skeletal network of megascleres. C, SEM of spicules megascleres from the holotype. D, SEM of spicules microscleres from the holotype. Scale bars: A = 5 mm; B = 300 μm; C, D = 50 μm.