Pseudictyota moreirae (L.F. Fernandes & Souza-Mosimann) 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 : 35

Pseudictyota moreirae (L.F. Fernandes & Souza-Mosimann) P.A. Sims & D. M. Williams , comb. nov.

( Figs 129–132 )

Basionym: Triceratium moreirae L.F. Fernandes & Souza-Mosimann (2001: 161 , figs1–21)

Synonyms: Biddulphia reticulata var. trigona Grunow in Van Heurck (1882: pl.102, fig. 3) Biddulphia reticulata f. trigona A. Schmidt (1885 : pl. 85, fig. 8) non Biddulphia reticulata var. trigona Grunow in Van Heurck (1882: pl.102, fig. 3) Biddulphia reticulata f. trigona (Grunow) Grove & Sturt (1887: 74) nom. superfl.? Biddulphia reticulata var. trigona (A. Schmidt) Tempère & Peragallo (1911: 294 , nos 590–591) =? Biddulphia reticulata f. trigona A. Schmidt (1885 : pl. 85, fig. 8), nom. invalid?

Type:— “ Ratones River estuary [southeastern Brazil]; salinity 12–34, water temperature 18–30ºC… Holotype: slide n. 12553; FLOR Herbarium at Federal University of Santa Catarina, Brazil ” ( Fernandes & Souza-Mosimann 2001: 161) .

Valve outline triangular, margins straight, slightly convex or concave ( Fig. 129 ), length of margin 45–82μm. At each pole a barely raised elevation projects outwards, ocellus at its summit ( Fig. 132 ). Valve face slightly convex merging into rounded mantle up to 10μm deep ( Fig. 131 ). Valve face and mantle covered in irregular network of false pseudoloculi, spinule or papillus above each junction ( Figs 130, 132 ), 2–2.5 false pseudoloculi in 10μm. Basal layer covered in uninterrupted rows of poroid areolae. Externally poroids occluded by two types of vela, mostly by a raised cribrum, occasionally by a specialised pore, usually one within each sector ( Fig. 130 , arrow). Valve mantle attached to border of flat, hyaline expanded valve margin by a regular row of buttressed costae ( Fig. 131 ). Single rimoportula present at base of each elevation, opening through tubular spine, internally a slit between raised lips.

Observations:— For additional information on this species see Fernandes & Souza-Mosimann (2001).

The synonymy is complex. Biddulphia reticulata var trigona Grunow in Van Heurck (1882: pl.102, fig. 3) was described from “Java”; Biddulphia reticulata f. trigona (A. Schmidt 1885: pl. 85, fig. 8) was described from “Ngucy (Weissfl.)” but there is no indication in the text that it was based on Grunow’s concept. However, the two appear the same. Grove and Sturt explicitly state that their combination Biddulphia reticulata f. trigona (Grunow) Grove & Sturt is based on Grunow’s concept ( Grove & Sturt 1887: 74) but it is probably a superfluous combination. Finally, Tempère & Peragallo appear to make the combination Biddulphia reticulata var. trigona (A. Schmidt) Tempère & Peragallo (1911: 294 , nos 590–591) but no reference is given to either a publication or to a figure and it is probably invalid.

This description is based on specimens from Thursday Island, Queensland, Australia.

Figures

FIGURES 129–132. Pseudictyota moreirae (Fernandes & Souza-Mosimann) P.A. Sims & D.M. Williams (Thursday Island, Queensland, Australia). Fig. 129. Triangular valve exterior with barely raised elevations capped by ocelli at apices, the opening from a rimoportula at each base and irregular network of false pseudoloculi covering valve; scale bar = 10 μm. Fig. 130. False pseudoloculi, papillae on outer wall, basal layer of poroid areolae most occluded by cribra, a specialised pore (arrow) in most sectors; scale bar = 1 μm. Fig. 131. Mantle view with attached girdle bands, rounded mantle incurved where it links to expanded valve margin by costae, surface ridged spinules; scale bar = 10 μm. Fig. 132. Ocellus with hyaline rim, irregular network of false pseudoloculi with surface papillae; scale bar = 2 μm.