Trilamina nitescens (Greville) J. Witkowski, P.A. Sims, N.I. Strelnikova & D.M. Williams, 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

publication ID

https://doi.org/ 10.11646/phytotaxa.209.1.1

persistent identifier

https://treatment.plazi.org/id/ED69878E-097C-FB1E-FF2F-FC65FC06212B

treatment provided by

Felipe

scientific name

Trilamina nitescens (Greville) J. Witkowski, P.A. Sims, N.I. Strelnikova & D.M. Williams
status

comb. nov.

1. Trilamina nitescens (Greville) J. Witkowski, P.A. Sims, N.I. Strelnikova & D.M. Williams , comb. nov.

(SEM: Figs 217–222 View FIGURES 217–222 ; LM: Figs 223–229 View FIGURES 223–229 )

BASIONYM: Triceratium nitescens Greville (1865a , Transactions of the Microscopical Society of London, New Series 13: 8, pl. II, fig. 19).

TYPE:—‘Barbadoes deposit, Cambridge estate’ (BM3198, holotype! = Fig. 228 View FIGURES 223–229 ; Williams 1988: 56).

Frustules rectangular to subrectangular in girdle view, valves tripolar ( Fig. 223–229 View FIGURES 223–229 ) with deeply concave sides and wedge-shaped ( Figs 227, 229 View FIGURES 223–229 ) to linear projections ( Figs 223, 228 View FIGURES 223–229 ), rounded or tapering near the pole. An inconspicuous pseudocellus is located at each pole ( Fig. 219 View FIGURES 217–222 ). The valve centre, with a triangular or hexagonal outline ( Figs 224 View FIGURES 223–229 versus 223), is convex and mostly hyaline, with few irregular rings of sparse poroid areolae near the margins ( Fig. 218 View FIGURES 217–222 ). The marginal parts of the projections are perforate, with poroid areolae arranged in transverse, short, parallel rows that continue down the mantle ( Figs 218–219 View FIGURES 217–222 ). Size of areolae diminishes toward the mantle margin ( Figs 218–219 View FIGURES 217–222 ). Valve face-mantle transition is gradual, mantle is steep and shallow ( Figs 217–218 View FIGURES 217–222 ). The central part of each projection bears a prominent, depressed hyaline area tapering toward the pole ( Figs 217–218 View FIGURES 217–222 ). A prominent network of robust costae ( Figs 220–221 View FIGURES 217–222 ) is present on the valve interior. The most prominent of these costae are associated with the depressed hyaline areas within each projection ( Fig. 220 View FIGURES 217–222 ). Tapering costae give rise to transverse, shorter costae that continue down the mantle and terminate at the inwardly expanded hyaline mantle margin ( Fig. 221 View FIGURES 217–222 ). On the valve interior, each side of the central area is associated with a robust costa or a transverse fold ( Figs 220–221 View FIGURES 217–222 ). A single, inconspicuous rimoportula is placed next to one of the folds ( Fig. 220 View FIGURES 217–222 ). On the interior, it is a slit between two slightly raised lips ( Fig. 220 View FIGURES 217–222 ). The rimoportula lacks a tube, and thus it is indistinguishable from other perforations on the exterior ( Fig. 218 View FIGURES 217–222 ). Valvocopula is closed, comparable in depth to the mantle, attached to the valve by means of a fossa that embraces the inwardly expanded hyaline margin of the mantle, large clasping devices attached at mid-point of each side to internal costae or folds that line the central area ( Fig. 221 View FIGURES 217–222 ), and small clasping devices located in regular intervals along the sides of each projection ( Fig. 222 View FIGURES 217–222 ). The small clasping devices attach to each of the transverse costae that run down the mantle ( Fig. 222 View FIGURES 217–222 ). Valvocopula is mostly hyaline, with a single row of poroids located next to the advalvar edge ( Fig. 221 View FIGURES 217–222 ), interrupted at mid-point of each side, due to the presence of the large clasping devices. Measurements (n =13): average side length: 44.7–124.5 µm; 3–4 costae in 10 µm measured along the valve face margin; 3–5 areolae in 5 µm measured across a projection; 6–7 rows of areolae in 10 µm, measured along a projection.

Geographic and stratigraphic distribution ( Fig. 10, sites 14, 18):

(a) specimens:

Middle Eocene-early Miocene: Oceanic Formation outcrops at Cambridge Estate: BM3198 ( Fig. 228 View FIGURES 223–229 , holotype); Joe’s River : BM63659 ( Fig. 223 View FIGURES 223–229 ), BM65907, BM coll. Adams H 772.

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

Phytotaxa 209 (1) © 2015 Magnolia Press • 31

Late Eocene-earliest Oligocene: Oamaru , New Zealand: BM stub P.137 ( Figs 217 – 222 View FIGURES 217–222 ), BM coll. Adams TS694 ( Fig. 224 View FIGURES 223–229 ), BM63658 ( Fig. 225 View FIGURES 223–229 ), BM61163, BM61164 ( Figs 226 and 229 View FIGURES 223–229 ), BM coll. Adams GC 3331, GC: 3332 ( Fig. 227 View FIGURES 223–229 ), H302, J3666.

(b) records:

Middle Eocene-early Miocene: Oceanic Formation outcrops at Cambridge Estate: Greville (1865a: 8, pl. II, fig. 19), Williams (1988: 56).

Late Eocene-earliest Oligocene: Oamaru View in CoL , New Zealand: Schmidt (1888: taf. 127, fig. 19), Laporte & Lefébure (1929: pl. II, fig. 14, 1930: pl. XIX, fig. 131), Reed (1991: pl. 16, fig. 210); Oamaru Diatomite View in CoL outcrops at Cormack’s Siding: Grove & Sturt (1886: 328); Allan’s Farm, Bain’s Upper, Jackson’s Paddock, Mavor’s: Desikachary & Sreelatha (1989 261, pl. 126, figs 4–8; not fig. 2); Otago, New Zealand; Totara, New Zealand: Desikachary & Sreelatha (1989: 261)

Observations:—Based on superficial resemblances, Greville (1865a: 8) suggested that T. nitescens was ‘allied’ to Triceratium lobatum Greville (1863: 233) . Prior to publishing the description of T. nitescens, Greville proposed a number of other similar taxa in addition to T. lobatum : Triceratium westianum ( Greville 1861a: 43, pl. IV, fig. 11), Triceratium rotundatum ( Greville 1861c: 75, pl. IX, fig. 6), Triceratium denticulatum ( Greville 1863: 233, pl. IX, fig. 14) and Triceratium obesum ( Greville 1864b: 90, pl. XIII , fig. 11). None of these, however, were indicated by Greville to be a possible close relative of T. nitescens . Of all these taxa, T. westianum has been available for SEM examination (see below). However, the presence of extensive hyaline areas and an overall similar pattern of internal costae in all of these species has prompted their transfer to Trilamina .

Kingdom

Chromista

Phylum

Ochrophyta

Class

Bacillariophyceae

Order

Biddulphiales

Genus

Trilamina

Loc

Trilamina nitescens (Greville) J. Witkowski, P.A. Sims, N.I. Strelnikova & D.M. Williams

Witkowski, Jakub, Sims, Patricia A., Strelnikova, Nina I. & Williams, David M. 2015
2015
Loc

Middle

Williams, D. M. 1988: 56
Greville, R. K. 1865: 8
1865
Darwin Core Archive (for parent article) View in SIBiLS Plain XML RDF