Cerataulus granulata (Roper) P.A. Sims & D.M. Williams, 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 : 44-46

Cerataulus granulata (Roper) P.A. Sims & D.M. Williams , nov. comb. ( Figs 154–155 )

Basionym:— Biddulphia granulata Roper (1859: 13 , pl. 1, figs 10, 11, pl. 2, fig. 12)

Synonyms:— Denticella granulata (Roper) Van Heurck (1896: 467 , fig. 201), invalid Odontella granulata (Roper) R. Ross in Hartley (1986: 609)

Type:— “Marine or brackish water. Dredged off Caldy, Rev. J. Guillemard; Barking Creek, Roper; Gorleston, Col. Baddeley; New Brighton, Cheshire, Comber” ( Roper 1859: 13).

UK: New Brighton, Cheshire [Merseyside] ( BM 22773 , Roper slide, two specimens indicated by black ink dots; BM 22776 , Roper slide, syntypes) ; Gorleston, Norfolk ( BM 1388 ; BM 1488 ; BM 4566 ; BM 21179 , Roper slide, two specimens selected by Maltwood Finder coordinates; BM 22768 , Roper slide, one specimen selected by Maltwood Finder coordinates; BM 22770 , Roper slide, three specimens selected by Maltwood Finder coordinates; BM 22772 , Roper slide, one specimen selected by black ink dots, syntypes) ; Caldy, Wirral Peninsula ( BM 22775 , ‘ Dredged off Caldy’ , Roper slide, one specimen selected by black ink dots, syntype) ; Barking Creek (joining the river Roding to the River Thames ), Roper ( BM 21225 , specimen at N41 3, England Finder, syntype) .

Valves bipolar, lanceolate with elevations in opposing directions ( Fig. 154 ), ocellus on each summit, with two stout hollow spines, openings of rimoportulae, lying centrally in subpolar position on opposing sides of central annulus (sternum). Valve exterior with transapical quadruple rows of poroids meeting annulus (sternum) extending between rimoportulae ( Fig. 155 , arrow).

Observations:— From a nomenclatural point of view, rather than a taxonomic point of view, the names Biddulphia granulata Roper and Cerataulus turgidus (= Denticella turgida Ehrenberg ) have become entwined. This is largely due to the account given by Roper of his species. He wrote: “The species here figured does not appear to have been noticed by Professor Smith, who refers to the Odontella turgida of Kützing as a probable variety of B. aurita […]” ( Roper 1859: 13). Roper cites as synonyms Denticella turgida , Odontella turgida and Denticella tumida (as illustrated by Bailey 1851 but not Ehrenberg 1844a: 266). Roper wanted to place his specimens in Biddulphia and with the view that his specimens were synonymous with Denticella turgida he recognised that the name Biddulphia turgida already existed and so chose a new name— Biddulphia granulata —and described it as a new species ( Roper 1859: 13). It has been assumed in some diatom name catalogues (e.g., Mills 1933: 289) that Roper’s new name was superfluous as turgida remained valid. Yet Biddulphia granulata and Denticella turgida are different species ( Sims & Witkowski 2012).

Even so, Roper’s Biddulphia granulata has been transferred to Denticella by Van Heurck (1896: 467, fig. 201, although this appears to be invalid) and Odontella Ross (in Hartley 1986: 609, the combination made with no comment). Biddulphia turgida was first mentioned by Okeden (1855) with reference to William Smith’s second volume of Synopsis of British Diatomaceae ( Smith 1856: 50) ; Smith’s name was based on Cerataulus turgidus (Ehrenberg) Ehrenberg.

For completion a few notes on Denticella turgida are required. A few years after describing Denticella turgida, Ehrenberg wrote: “Eine zweite neue Gattung bildet die 1840 aus Norwegen verzeichnete Denticella turgida , wovon damals nur 1 Exemplar bekannt war, während sich nun die ganze Entwickelungsgeschichte derselben hat übersehen lassen, wodurch denn auch die Absonderung von der kettenbildenden. Denticella als Cerataulus , nöthbig geworden ist” ( Ehrenberg 1844a: 264–265), and went on to transfer it to Cerataulus as Cerataulus turgidus ( Ehrenberg 1844a: 271) . Later, several persons moved Denticella turgida into Odontella ( Kützing 1844: 137, Pritchard 1852: 470, De Toni 1894: 864).

Here, Biddulphia granulata has been transferred to Cerataulus .

This description is based on specimens from “Wunderluss” (locality unknown, ex Brigger colln, BM).

Figures

FIGURES 153–156. Details of two species currently placed in Cerataulus but with characters associated with Trieres and Parodontella. Figs 153,155.Cerataulus strelnikovae P.A. Sims and D.M. Williams, sp. nov. (Vema Cruise 17, core 107, 175cm). Fig. 152. Valve exterior, broadly lanceolate valve with apical elevations lying in opposing directions, 5 stout subcentral spines, the openings of rimoportulae surrounding a central annulus; scale bar = 10 μm. Fig. 155. Detail of transapical rows of irregularly arranged fine poresr within annulus, linked spinules covering annulus (sternum); scale bar = 1 μm. Figs 154–156. Cerataulus granulata (Roper) P.A. Sims & D.M. Williams, comb. nov. (“Wunderluss”, locality unknown, ex Brigger colln, BM). Fig. 154. Valve exterior, lanceolate valve with elevations in opposing directions, an ocellus on summit, 2 stout hollow spines, the openings of rimoportulae lying centrally in a subpolar position on opposing sides of a central sternum; scale bar = 10 μm. Fig. 155. Detail of valve exterior with transapical quadruple rows of fine pores meeting annulus (sternum) extending between rimoportulae; scale bar = 1 μm.