Parodontella fimbriata (Greville) D. M. Williams & P.A. Sims, 2018

Sims, Pat A., Williams, David M. & Ashworth, Matt, 2018, Examination of type specimens for the genera Odontella and Zygoceros (Bacillariophyceae) with evidence for the new family Odontellaceae and a description of three new genera, Phytotaxa 382 (1), pp. 1-56 : 13

Parodontella fimbriata (Greville) D. M. Williams & P.A. Sims , comb. nov. ( Figs 44–50 )

Basionym:— Biddulphia fimbriata Greville (1865a: 6 , pl. 1, fig. 4) non Biddulphia fimbriata (Wallich) Mann (1925: 39) (= Triceratium fimbriatum Wallich 1858: 247 , pl. 12, figs 4–9)

Synonyms:— Odontella fimbriata (Greville) Grunow (1884: 58) ? Denticella fimbriata (Greville) Grunow (1884: 58) Odontella fimbriata (Greville) Schrader in Schrader & Fenner (1976: 992, pl. 20, fig. 6), nom. superfl.

Type:— Barbadoes, Johnson 1863, 1864 ( BM 3186 (1863), lectotype; BM 3197 (1864), syntypes) .

Valves broadly lanceolate with acuminate apices ( Figs 44–47 ), length 187–225μm (Greville’s specimen measures 92.5–102μm) breadth 104–109μm, striae on mantle exterior c. 15 in 10μm. Valve face lanceolate with outwardly directed slightly curved elevations at each pole ( Figs 46–47 ), ocellus on distal side of summit ( Fig. 48 ). Well-developed marginal ridge of solid spines, fused at base, separates valve face from deep mantle expanded at its centre ( Figs 44, 47 ). Valve structure loculate with internal foramina ( Fig. 50 ), exterior with single or double rows of slightly radially aligned poroids between hyaline lines on valve face ( Fig. 49 ) and between barely raised costae on mantle ( Fig. 48 ). Spinules, some long, on valve face and mantle ( Fig. 49 ). Rimoportulae 8–12, opening through very long slender spines lying on each side of valve face just within marginal ridge ( Fig. 47 ). Internal opening a slit across a sunken papillus ( Fig. 50 ).

Observations:— The description above is based on material from Sengilei, Russia ( BM). It has been found in: Cambridge, Barbadoes (Johnson in Greville 1865a); Navarin Basin Province, Bering Sea ( Baldauf & Barron 1987: Pl. 10, fig. 15); Oligocene sediments of the Norwegian Sea ( Schrader & Fenner 1976); lower Oligocene sediments of the southwestern Pacific ( Hajós 1976: Pl. 22, figs 7, 8).

Figures

FIGURES 44–50. Parodontella fimbriata (Greville) D.M. Williams & P.A. Sims (Sengilei, Ulyanovsk, Russia). Fig. 44. Valve flat with broad lanceolate valve face, elevations with spiny marginal ridge extending between apices; scale bar = 50 μm. Fig. 45. Valve interior with openings from rimoportulae lying at margin of valve face; scale bar = 50 μm. Fig. 46. Reproduction of illustration for Biddulphia fimbriata from Greville (1865a: plate 1, fig. 4) (not to scale). Fig. 47. Valve exterior tilted with narrow, slightly curved elevations at apices, marginal ridge of fused spines buttressed to mantle at base central annulus (arrow) (sternum), 11 hollow spines positioned just within valve face, long spinules on valve face, short ones scattered on mantle; scale bar = 50 μm. Fig. 48. Pole with outwardly directed curved elevation with expanded hyaline rim to distally inclined ocellus; scale bar = 20 μm. Fig. 49. Exterior with irregular rows of transapically aligned poroids; scale bar = 5 μm. Fig. 50. Interior with foramina and openings from two rimoportulae; scale bar = 10 μm.