Entogoniopsis tabellaria (Brightwell) J. Witkowski, P. A. Sims, N.I. Strelnikova & D.M. Williams, comb., 2015

Witkowski, Jakub, Sims, Patricia A., Strelnikova, Nina I. & Williams, David M., 2015, Entogoniopsis gen. nov. and Trilamina gen. nov. (Bacillariophyta): a survey of multipolar pseudocellate diatoms with internal costae, including comments on the genus Sheshukovia Gleser, Phytotaxa 209 (1), pp. 448-450 : 448-450

15. Entogoniopsis tabellaria (Brightwell) J. Witkowski, P. A. Sims, N.I. Strelnikova & D.M. Williams, comb.

nov.

(SEM: Figs 193–198 , LM: Figs 199–204 )

BASIONYM: Triceratium tabellarium Brightwell (1856 , Quarterly Journal of Microscopical Science 4: 275, pl. XVII , fig. 15).

TYPE:—‘Honduras’.

Triceratium pallidum Greville (1864a: 84 , pl. XI, fig. 7).

TYPE:—‘Barbadoes deposit, Cambridge Estate’ (BM2972, holotype!).

Triceratium grave A.W.F. Schmidt (1882 : taf. 77, fig. 17).

TYPE:—‘Jérémie’.

Biddulphia tabellarium (Brightwell) Boyer (1900: 718) .

Trigonium tabellarium (Brightwell) Mann (1907: 295) .

Biddulphia riedyi ( Hanna & Grant 1926: 132, pl. 14, fig. 6).

TYPE:—‘ Maria Madre Island , Tres Marias Group, Mexico’ (CAS 200035, holotype!) .

Triceratium riedyi (Hanna & Grant) Reinhold (1937: 128 , pl. XX, fig. 6).

Valves tripolar with rounded or acute poles ( Figs 199–204 ), valve face undulate, with a distinct trifolium and raised poles ( Figs 193–194 ). Summits of the polar elevations either convex and sloping ( Fig. 193 ), or flat and cut off from the adjacent depressed sectors ( Fig. 194 ), in both cases bearing pseudocelli ( Figs 193–194 ). Hyaline marginal ridge, sometimes inconspicuous, extends between the polar elevations ( Figs 193–194 ). Whole valve face perforated by poroid areolae, occluded by distinctly domed cribra ( Figs 193–195 ). Within the pseudocelli, porelli are occluded by flat rotae ( Fig. 195 ). Mantle shallow, steeply downturned ( Fig. 193 ), areolate ( Fig. 195 ), with a hyaline margin that is slightly expanded inwardly ( Fig. 197 ), but can also have a slight outward expansion ( Fig. 193 ). On the valve interior, there is a series of costae along each side of the valve, reaching from the expanded mantle margin to the marginal part of the valve face ( Figs 197–204 ). Near the poles, the costae are shorter. Next to the edges of the trifolium, the costae reach further toward the centre of the valve face, and are more robust ( Figs 199–204 ). Cingulum is composed of multiple closed bands that bear several circumferential rows of poroid areolae separated by hyaline areas ( Figs 196, 198 ). Valvocopula bears two rows of areolae ( Fig. 198 ) and attaches to the internal costae by means of clasping devices, and to the expanded mantle margin, by means of a fossa ( Fig. 198 ). Measurements (n= 19): average side length: 64.3–207.4 µm; 2–3 areolae in 10 µm; 1–2 costae in 10 µm measured along the valve face margin. No rimoportulae were seen.

Geographic and stratigraphic distribution ( Fig. 10, sites 14, 21, 26, 29–37, 39*; questionable records indicated with an asterisk):

(a) specimens:

Middle Eocene-early Miocene: Barbadoes: BM coll. Adams: H907, TS756. Oceanic Formation outcrops at Cambridge Estate: BM2972, BM coll. Adams F1389; Conset: BM stub P.1338 ( Fig. 197 ); Joe’s River: BM stub P.1351 ( Figs 193, 195 ), BM coll. Adams TS927; Newcastle: BM65915; Springfield: BM coll. Adams: Bess343, GC3431.

Early Miocene: Jeremié, Haiti: BM coll. Adams: J661, TS543 ( Fig. 202 ).

Late Miocene: Maria Madre Island, Mexico: BM stub P.1335 ( Figs194, 196, 198 ), BM coll. Adams TS582 ( Fig. 204 ).

Recent: Campeche Bay: BM55099; Colón, Panama: BM63761 ( Fig. 200 ), BM coll. Adams: F1390, F1391; Manila, Philippine Islands: BM63765 ( Figs 199, 201 ); Philippine Islands: BM coll. Adams TS507 (label reads: ex Mann); Toamasina / Tamatave, Madagascar: BM coll. Adams TS451 ( Fig. 203 ).

(b) records:

Early Miocene: Jeremié, Haiti: Schmidt (1882: pl. 77, fig. 17), Truan & Witt (1888: 22, pl. VII, figs 13, 19, 21).

Middle Miocene : Wonosari-Series, Java: Reinhold (1937: 128, pl. 20, fig. 6).

Late Miocene: Maria Madre Island, Mexico: Hanna & Grant (1926: 132, pl. 14, fig. 6), Southern Baja California: Hanna & Brigger (1966: 300, fig. 34).

Recent: Campeche Bay: Cleve (1878: 17); Honduras (presumably from mahogany logs): Brightwell (1856: 275, pl. XVII , fig. 15); Philippine Islands: Mann (1925: 46); Galapagos Islands and Virgin Islands: Cleve (1878: 17); off northern Mauritius: Desikachary (1989: 12, pl. 805, figs 1–6).

Age unspecified, presumably Recent: Dredgings in the area of Galapagos Islands and in the Bering Sea: Mann (1907: 296). 3

Observations:— Entogoniopsis tabellaria has a high degree of variation in the number of internal costae per side, which is dependent on the valve diameter; the polar elevations vary from flat to convex. It is also unusual in having

3. The Bering Sea record is questionable: all verified records of E. tabellaria are from tropical and subtropical latitudes. No figures were provided by Mann (1907), and therefore verification is not possible.

ENTOGONIOPSIS GEN. NOV. AND TRILAMINA GEN. NOV. (BACILLARIOPHYTA)

Phytotaxa 209 (1) © 2015 Magnolia Press • 27 distinctly domed vela. Apart from E. tabellaria and E. inflata , all other species of Entogoniopsis documented so far have flat, slightly sunken cribrate or volate occlusions to the areolae.

Entogoniopsis tabellaria has a remarkably convoluted nomenclatural history. Originally proposed as Triceratium tabellarium Brightwell (1856: 275 , pl. XVII , fig. 15), it was based on material from mahogany logs imported from Honduras, suggesting that the samples studied by Brightwell were of modern origin. This is corroborated by the Comber Catalogue in BM. Brightwell’s brief diagnosis is accompanied by a single line drawing that reveals little detail of valve morphology. In 1882, Grunow proposed the variety T. tabellarium var. diplosticta (in Schmidt 1882: taf. 77, figs 1, 2). Because of the poor quality of Brightwell’s (1856) original line drawing, the remarkably detailed illustrations in Schmidt (1882, taf. 77, figs 1–2, 2a) are inconclusive, as it is impossible to judge which features separate the variety from the species. Furthermore, on the same plate there are illustrations of Triceratium grave A. Schmidt (taf. 77, fig. 17), Triceratium venulosum Greville (taf. 77, figs 6–9) and some valves Schmidt considered as possible variants of T. tabellarium . Cleve (1878) also reported T. tabellarium as living (from the Virgin Islands, Galapagos and Campeche Bay) but indicated that Triceratium brevinervum Greville (1865b : pl. IX, fig. 26) and Triceratium venulosum Greville (1864b : pl. XIII , fig. 21) were synonyms of T. tabellarium . Both T. brevinervum and T. venulosum were originally illustrated with inconclusive line drawings giving a poor understanding of the valve morphology. The holotype of T. brevinervum is of poor quality ( Williams 1988: pl. 59, fig. 5) and no holotype could be found for T. venulosum ( Williams 1988: 60) . Therefore, it is impossible to verify whether the synonymy suggested by Cleve is justified. Boyer (1900) transferred T. tabellarium to Biddulphia and further extended the list of synonyms, including Triceratium johnsoni Ralfs in Pritchard (1861: 854) and Triceratium pallidum Greville (1864a : pl. XI, fig. 7). The former species was first proposed without an illustration and thus is unverifiable as a synonym of T. tabellarium . The holotype of T. pallidum does resemble T. tabellarium in having a trifolium ( Williams 1988, pl. 66, figs 6–7; BM2972, holotype). LM examination indicates that also the density of costae and areolation of T. pallidum is consistent with the range of variation documented for E. tabellaria .

Later, Mann (1907) transferred T. tabellarium to Trigonium , and included T. grave among its synonyms. Hanna & Grant (1926: 132) proposed Biddulphia riedyi , which Hanna & Brigger (1966) considered a junior synonym of Triceratium tabellarium . Our examination of B. riedyi from Maria Madre Island ( Mexico, type locality, holotype on slide CAS 200035) and Java supports the view that B. riedyi is synonymous with T. tabellarium .

From early Eocene sediments of the middle Urals area, Schibkova (in Krotov & Schibkova 1959: 120) proposed T. tabellarium var. areolata . No specimens of this variety were available to us; the description makes no mention of valve face undulations that could indicate the presence or absence of the central trifolium. In comparison to T. tabellarium var. diplosticta, Schibkova states that T. tabellarium var. areolata lacks ‘lines’ along the margin. The figure provided by Schibkova ( Krotov & Schibkova 1959: fig. 3.3), however, appears to show faint, short transverse lines along each margin of the valve face, which may represent internal costae. Given these uncertainties, the relationships of T. tabellarium var. areolata cannot be clarified until the material of Krotov & Schibkova (1959) has been reexamined.

No specimens of extant E. tabellaria were available for SEM examination. However, the morphology of the specimens from Campeche, Philippines, Panama and Madagascar examined in LM is consistent with those of Miocene age, e.g., from Madria Madre Island, Mexico and from Java. Valves of the same general morphology are also found in the Oceanic Formation sediments exposed in Barbadoes ( Figs 193, 195, 197 ); the degree of pseudocellus convexity ( Figs 195–196 ) is the only morphological feature that distinguishes specimens from Barbadoes from those from the Miocene deposits. This, in our opinion, does not warrant separation and therefore we interpret them as conspecific.

Figures

FIGURES 193–198. Scanning electron micrographs of Entogoniopsis tabellaria from Joe’s River (Figs 193, 195) and Conset (Fig. 197), Barbadoes, and Maria Madre Island, Mexico (Figs 194, 196, 198). Fig. 193: Oblique external view of a specimen with convex summits of the polar elevations. Note the well-preserved domed vela. Arrowhead points to the inconspicuous hyaline marginal ridge. Arrow indicates the slight outward expansion of the hyaline mantle margin. Fig. 194: Oblique external view of a specimen with flat summits of the polar elevations, and displaced girdle elements preserved. Fig. 195: Detail of the specimen in Fig. 193, showing well-preserved rotae within the porelli of the pseudocellus, and domed cribra occluding the areolae. Fig. 196: Detail of the specimen in Fig. 194, showing a detail of the polar pseudocellus, distinctly cut off from the adjacent depressed sector, and the detached girdle elements, which likely represent copulae (C and C?). Fig. 197: Oblique internal view, showing the internal costae and the inwardly expanded mantle margin (arrowhead). Fig. 198: Internal view of a specimen with attached valvocopula (VC), and a preserved displaced copula (C). Arrowhead points to one of the clasping devices linking the valvocopula to the internal costae.

FIGURES 199–204. Light micrographs showing the range of morphological variation in Entogoniopsis tabellaria. Figs 199, 201: BM63765, Manila, Philippine Islands. Fig. 200: BM63761, Colón, Panama. Fig. 202: BM coll. Adams TS543, Jérémie, Haiti (label on slide: ‘Triceratium grave’). Fig. 203: BM coll. Adams TS451, Tamatave, Madagascar (label on slide: ‘T. grave’). Fig. 204: BM coll. Adams TS582, Maria Madre Island, Mexico (slide label reads: ‘Biddulphia riedyi’).