Thalassionema cf. frauenfeldii HK 372 (Figs 65–68) Material studied: —Wild and cultured (HK 372) material from the same collection: ECT 4120, collected from plankton tow at Hunting Island, South Carolina, USA (32° 20.56’ N, 80° 22.80’ W). Description: —Valves observed were 79.6–83.9 μm long, 2.7–3.1 μm wide, with areolar densities of 5–6 areolae in 10 μm along the margin. There was a rimoportula at the very end of each pole. Internally, each rimoportula appeared to be situated at the junction of the face and mantle, and its slit composed of symmetric coverings, which were tangentially arranged. Externally, the rimoportula opening was underneath a broad spine at one pole. Girdle bands were open and without pores. Remarks: —Measurements of specimens from the DNA voucher fit well within the published ranges of T. frauenfeldii and T. bacillare (summarized in Sugie & Suzuki 2015). It keyed out to T. frauenfeldii according to Sugie and Suzuki (2015). While it had the relatively simple areolar structure (each areola spanned by a simple unbranched bar) of T. frauenfeldii as illustrated by those authors and by Hasle (2001), its end poles were not strongly different from one another, and consequently it keyed out to T. bacillare in Hasle (2001). Sequences from this strain were reported in Lobban and Ashworth (2014a) as belonging to T. frauenfeldii strain HK 372.

Published as part of Sabir, J. S. M., Theriot, E. C., Lobban, C. S., Alhebshi, A. M., Al-Malki, A. L., Hajrah, N. H., Khiyami, M. A., Obaid, A. Y., Jansen, R. K. & Ashworth, M. A., 2018, Systematics of araphid diatoms with asymmetric rimoportulae or densely packed virgae, with particular attention to Hyalosynedra (Ulnariaceae, Bacillariophyta), pp. 1-49 in Phytotaxa 347 (1) on pages 25-26, DOI: 10.11646/phytotaxa.347.1.1, http://zenodo.org/record/13707999