Moralesonia D. M. Williams, Ts. Georgiev, T. M. Schust. & C. E. Wetzel, 2024

Williams, David M., Georgiev, Tsvetoslav, Schuster, Tanja M. & Wetzel, Carlos E., 2024, The relationships of Eunotogramma frauenfeldii (Bacillariophyta) I. An account of its structure and description of the new genus Moralesonia, Plant Ecology and Evolution 157 (3), pp. 270-290 : 270-290

Moralesonia D. M. Williams, Ts. Georgiev, T. M. Schust. & C. E. Wetzel gen. nov.

Type species.

Moralesonia frauenfeldii (Grunow) D. M. Williams, Ts. Georgiev, T. M. Schust. & C. E. Wetzel , comb. nov.

Etymology.

Named for the late Eduardo Morales (1968–2023, https://diatoms.org/news/in-memoriam-eduardo-a-morales).

Registration.

http://phycobank.org/104544

Description.

Valves lunate, each with two transapical ribs dividing valve into three ± equal parts. Transapical ribs evident, extending to mantle, internally raised, tapering towards mantle edge. Areolae ± round, radiating from eccentric hyaline centre, sometimes elongated. Rimoportulae absent. Few simple pores on valve surface. Cribra with well-developed, complex volate structure. External surface of valve ornamented. Girdle composed of few bands, all (presumed) copulae. ‘ Central area with radiating areolae’ is the proposed (putative) synapomorphy (diagnostic character) for this genus.

Notes.

We have included all specimens from various parts of the African continent in Moralesonia frauenfeldii and omitted those from other localities for the time being, except from two samples from the Nicobar Islands as they present a similar morphology. These specimens may not be Moralesonia frauenfeldii but, as yet, detailed examination has not been possible (see below). Of these, we have documented them according to the details available to us. The specimens from Australia have been given a specific name, while the others are left without names as relevant characters have yet to be identified. We have SEM details for some specimens from Île Rodriguez, but no LM specimen, so are unable to assign a holotype other than the SEM stub, which we are reluctant to do at this time as their longevity cannot be established with any certainty (Fig. 10 A – F ).

Figures

Figure 10. Moralesonia sp., SEM images, specimens from Mauritius, Rodriguez (Île Rodriguez), stub NHM I 6. A. Whole external view of valve, arrows indicate ribs, evident by clear area, extending through to entire mantle, indicating it as part of valve, dividing valve into three ± equal parts, scale bar = 10 µm. B. External view of pole, detail with absence of any pore-field, etc., scale bar = 1 µm. C. Detail of centre of valve, arrows indicating ‘ unadorned’ holes, scale bar = 1 µm. D. Centre of valve with radiating ‘ annulus’ (shown within white box), scale bar = 2 µm. E. External view of pole, with detail of cribra with well-developed, complex volate structure, scale bar = 1 µm. F. Additional external view of pole, with detail of cribra with well-developed, complex volate structure, scale bar = 2 µm.