Pyrgodiscus simplex Witt 1885: 30

Williams, David M. & Sims, Pat A., 2023, Notes on the diatom collection of the Natural History Museum, London (BM) VII: An account of some original specimens of Pyrgodiscus (Bacillariophyta) with notes on Stephanogonia (Bacillariophyta), Phytotaxa 589 (3), pp. 213-229 : 220-222

Pyrgodiscus simplex Witt 1885: 30 , pl. VI, fig. 6; Witt 1886: 166, pl. VI, fig. 6 (= Figure 24 )

( Figures 24–33 )

TYPE LOCALITY:— RUSSIA, ‘Arkhan- gel’skoye-Kurojedovo, Ulyanovsk’ , formerly Simbirsk , USSR, Witt 1885: 30, pl. VI, fig. 6; Witt 1886: 166, pl. VI, fig. 6

MATERIAL

RUSSIA, SARATOV, BM 64641! (eX Barker 185, twO specimens, FigUres 26–29 , specimen figUred: d = 54 μm, cdw = 34 μm), BM 65879! (eX FergUsOn, One specimen, FigUres 30–33 , specimen: d = 44 μm, cdw = 31 μm); CARLOVA, BM 66038! (Ferguson [ex Barker 171], One specimen: d = 51 μm, cdw = 33 μm); BR (Weissflog 1400 and Weissflog 2270, “O.Witt […] Archangelsk-Kurijedowo, Gouv. Simbirsk, Russland”)

ILLUSTRATIONS:— Schmidt 1886 [Jul. 1 st]: pl. 100, figs 13 (= Figure 25 ) [=Proschkina-Lavrenko: pl. 37, fig. 3, 1949] (“ Archangelsk (Weissfl.)”), fig. 14, “Simbirsk (Weissfl.); dieses räthselhafte Gebilde ist viell. die Unterschale eines Pyrgodiscus ”); Baranov 1942: pl.1, fig. 9.

Valves circUlar, diameter 40–52μm, with central dOme Or pillar, ca. 20μm in height, ca. 30–35μm. SUrface sUrrOUnding pillar areolate with evenly spaced stout spines, ca. 6–7, tapering towards tip. Series of spines surrounding surface of pillar, as small as those on lower part of valve.

The only specimens examined so far are from Ulyanovsk (Simbirsk).

Figures

FIGURES 24–33. Pyrgodiscus simplex Witt. 24. Reproduced from Witt 1885: 30, pl. VI, fig. 6. 25. Reproduced from Schmidt 1886: pl. 100, fig. 13. 26–29. BM 64641 eX Barker 185, d = 54 μm, cdw = 34 μm; 30–33. BM 65879 eX FergUsOn, d = 44 μm, cdw = 31 μm. Scale bars = 5 µm (Figs 26–29), 10 µm (Figs 27–33).