Bacillariophyceae - Rhaphoneidales - Rhaphoneidaceae

"Description: Eight individual valves were measured and examined in LM and SEM. The valves are rectangular in girdle view and lanceolate in valve view, with a slightly depressed valve face centre (Figs 4, 9), and pointed (e.g. Figs 12, 56) to apiculate (e.g. Figs 34) apices. The transition between the mantle and the valve is distinct. The mantle bears three rows of areolae and a smooth hyaline margin. Length is 4076 m, and width at the centre 2437 m. A straight sternum, marking a break between the areolae in the central area, is not always distinct in LM (e.g. Figs 1112), but extends from the apical pore eld of one apex to the other. Striae, 58 in 10 m, are straight to slightly radiate, and continue around the apices. The areolae, 68 in 10 m, are subquadrate to rounded (Figs 2124) and occluded by a cribrum having circular plates with concentrically aligned, linear, interrupted openings, usually attached by four pegs (Figs 17, 20). The apical pore

elds are composed of narrow rows of poroids, radiating in a fan shape from the top of the sternum (Figs 9, 1920). A rimoportula is present on the valve face at each pole (Figs

17, 19, 2223), adjacent to the sternum, aligned perpendicular to the sternum. The outer openings of the rimoportulae are simple holes (Figs 17, 19) opening internally by short,

attened tubes (Figs 2223).

Full reference: C. Figus and J. Witkowski. 2024. New taxa of the Rhaphoneidaceae Forti (Bacillariophyta) from the middle Eocene. Diatom Research 1-11

Belongs to Rhomboneis according to C. Figus and J. Witkowski 2024

Sister taxa: none

Type specimen: slide 27830C (Figs 9–10), deposited at Univer- sity of Szczecin Diatom Herbarium (SZCZ), an other (frustule). Its type locality is OPD Hole 1050A, which is in an Eocene marine mudstone in North Atlantic.

Ecology: "photoautotroph"

Distribution: found only at OPD Hole 1050A

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Specimen images are retrieved through the ePANDDA API.