Tetracyclus krasskei D. M. Williams, 2014

Williams, David M., 2014, The diatom genus Tetracyclus (Fragilariaceae, Bacillariophyta) from Chile, Phytotaxa 178 (2), pp. 151-155 : 153

Tetracyclus krasskei D. M. Williams , stat. nov. et nom. nov.

Basionym: Tetracyclus ellipticus var. lancea f. chilensis Krasske (1939: 357 , pl. 10, figs 14–19) non Biblarium chilense Ehrenb. 1854, p. 301 , 303, nom. nud.

Valves lanceolate, strongly tapering towards poles, 40–120 µm long, 25–35 µm wide (Figures 3, 4; Lange-Bertalot et al. 1996, Taf. 1, figs 3–5). Transapical ribs robust; predominantly primary, rarely secondary, usually more or less parallel, 2–3 in 10µm (Figures 3, 4; Lange-Bertalot et al. 1996, Taf. 1, figs 3–5). Striae more or less parallel, 4–8 rows between ribs. Sternum central, linear, marginally broader at the centre, obscure at the poles (Figures 3, 4). Rimoportulae not observed (absent?) (Figures 3, 4; Lange-Bertalot et al. 1996, Taf. 1, figs 3–5). Girdle bands numerous, open, septate (Figure 5; Lange-Bertalot et al. 1996, Taf. 1, figs 7, 8); septum extending up to ¼ length of valve from one pole (Figure 5; Lange-Bertalot et al. 1996, Taf. 1, figs 1, 2). Possibly 15–20 in total, differentiation not detected.

Type: CHILE: “Thermae of Puyehene, Peulo River, Fiord of Reloncavi, Lake Risopatrón, Pascua River, Yacuf snowdrift, near Puyuhuapi” ( Krasske 1939: 357) ( KASSEL Krasske Collection D III 204 = Figs 3–5, lectotype! designated here; three Krasske slides selected as syntypes in Lange-Bertalot et al. 1996: D. III 190, 191 and 204).