Ctenophora vertebra (W.Greg.) D.M.Williams & Van de Vijver, 2023

Williams, David M. & Vijver, Bart Van De, 2023, The diatom genus Ctenophora: A discussion on its morphology, relationships, and some species, Phytotaxa 632 (1), pp. 1-26 : 14

Ctenophora vertebra (W.Greg.) D.M.Williams & Van de Vijver , comb. nov. ( Figs 53–65 )

Basionym: Synedra vertebra (vertebrata) W.Greg . 1855 Quarterly Journal of Microscopical Science 3: 41, pl. IV, fig. 22 (= our Fig. 53 )

Synonym: Synedra pulchella var. vertebra (W.Greg.) Van Heurck 1896: 309 (see Smith, 1856: 104, “Synedra Vertebra, Greg. Mic. Journ. vol. 3. pi. iv. 22 = S. pulchella, Synop. xi. 84?”)

TYPE:— SCOTLAND, lacustrine sands, Glenshira, near Inverary ( BM 24988 !, isotype?, https://data.nhm.ac.uk/object/57f0e08a-1cdb-4262- 99e6-a64d88c254ec)

Registration: http://phycobank.org/104112

Valves lanceolate, tapering towards capitate poles; length ca. 44–104μm, width 2–4μm ( Figs 54–7 ). Sternum very narrow, regular, meeting distinctive ovoid central area, buttressed either sides of valve ( Figs 54–7 ). ‘Ghost striae’ present. Sternum meeting virgae, sternum larger than virgae, vimines reduced in size relative to virgae ( Figs 54–7 ). No data on apical pore fields, rimoportulae or girdle.

Only preserved LM specimens of Gregory’s Synedra vertebra have been available for examination and these are limited to one slide from Dickie’s collection in BM (BM 24988). There are no doubt other specimens. Gregory’s own collection is poorly catalogued in BM and hence difficult currently to use, but it is well-known that the Glenshira material was widely circulated.

Gregory noted of Synedra vertebra that “This form, which is very frequent in the deposit, belongs to the same division as S. pulchella and S. acicularis ” ( Gregory 1855: 41) ; Grunow (1862: 385) included it in his ‘2 Gruppe Ctenophora ’; Van Heurck gave a very brief description including it as a variety of Synedra pulchella ( Van Heurck 1896: 309) .

Figures

FIGURES 53–59: Ctenophora vertebra. Fig. 53, reproduction of drawing for Synedra vertebra Gregory (1855: pl. 4, fig. 22); Figs 54–57, LM micrographs of C. vertebra, BM 24988, ‘lacustrine sands, Glenshira,near Inverary,Scotland’.Scale bar = 10μm; Fig. 58, reproduction of Synedra acicularis W.Sm. (1853: 70, pl. 11, fig. 86; Fig. 59, reproduction of Synedra socialis Rabenh. (1853: 56, pl. 4, fig. 22).

FIGURES 60–65: SEM micrographs. Figs 60, 61, Fragilaria sp., external and internal view of plain central area; Fig. 62, Tabulariopsis australis (M. Perag.) D.M.Williams (1988: 249), detail of central area; Figs 63, 64, Hannaea baicalensis Genkal et al. (2008: 322), detail of central area, Fig. 63, external view, Fig. 64, internal view, with robust buttressed area; Fig. 65, Fragilaria sp. (Lake Baikal), whole valve, external view of plain central area. Scale = 1μm (Figs 60, 61), Scale = 2μm (Fig. 64), Scale = 3μm (Fig. 62), Scale = 5μm (Fig. 63, 65).