Encyonopsis indonesica Kapustin, Kulikovskiy & Kociolek sp. nov. Figs 1, 2, 3, 4

Holotype

( here designated): MHA 01105. Fig. 1B illustrates the holotype.

Type locality.

Indonesia, Island of Sulawesi, Lake Matano, 02°28.433'S, 121°15.710'E, leg. I. I. Ivanov, 14.XI.2010 .

Etymology.

The specific epithet refers to the type locality from Indonesia .

Description.

LM (Fig. 1A-J). Valves dorsi-ventral, semi-lanceolate, with a slightly convex dorsal margin and a nearly straight ventral margin. Apices slightly protracted, cuneate to slightly rostrate. Axial area very narrow, following the course of the raphe and central area not expressed. Raphe undulate. Striae indistinct in LM. Length 17-29 µm (21.9 ± 3.3; n = 16), breadth 3-4 µm (3.4 ± 0.3; n = 16), length/width ratio 5.7-7.4 (6.5 ± 0.6; n = 16).

SEM (Figs 2 - 4). External valve face occasionally covered with siliceous verrucae and numerous siliceous ribs of different lengths mostly aligned along the apical axis (Fig. 2A-F). Valve face delineated from the mantle by a thickened marginal ridge. Raphe distinctly undulate, with the proximal raphe ends deflected slightly towards the dorsal margin and the distal ends hooked strongly to the ventral side (Fig. 3E, F). Raised sterna border the raphe branches. Striae almost parallel at the valve center becoming weakly radiate towards the apices, 34-36 in 10 µm . Striae composed of 2-4 areolae on the ventral side and 5-6 areolae on the dorsal side. Areolae rounded and unoccluded, being occasionally slightly smaller near the valve margins, 50 in 10 µm . Internally, areolae rounded or transapically elongated located in a shallow groove. Internal proximal raphe ends obscured; distal raphe ends terminate in well-developed helictoglossae (Fig. 4A-E). A thin, plate-like silica thickening present between helictoglossa and apices (Fig. 4F, G).