Mastogloia crucicula var. alternans Zanon 1948

Pennesi, Chiara, Poulin, Michel, Hinz, Friedel, Romagnoli, Tiziana, Stefano, Mario De & Totti, Cecilia, 2013, Comparison of two new species of Mastogloia (Bacillariophyceae) with other small members of section Ellipticae, Phytotaxa 126 (1), pp. 1-21 : 6

Mastogloia crucicula var. alternans Zanon 1948 ( Figs 15–20 )

References:— Zanon 1948, p. 212, fig. 12; Ricard 1973, pl. 3, fig. 12, as M. crucicula ; Witkowski et al. 2000, p. 243, pl. 75, figs 4–6; Hein et al. 2008, p. 63, pl. 36, fig. 5.

Material:— Sample from Siladen, Indonesia. SEM stub no. DISVAR-ANS3SP4A.

SEM morphology: —The variety alternans differs from the nominate variety by its small size ( Table 1) and the presence of two bilobed partecta diagonally opposite on each side of the valvocopula ( Figs 18, 20 ). Length: 7.8–14.2 µm; width: 4.8–7.6 µm ( Table 1).

Figures

FIGURES 15–20. Mastogloia crucicula var. alternans, SEM (DISVAR-ANS3SP4A, Siladen, Indonesia). (15) External view of valve showing straight raphe branches and thin fascia; (16) External view of valve center showing proximal raphe endings and areolae with crescentic edges; (17) Internal view of valve center showing areolae and proximal raphe endings; (18) Internal valve view showing two bilobed partecta (arrowhead) in opposite quadrant; (19) External view of tilted specimen showing one partectal pore; (20) Internal view of tilted valve showing raised raphe-sternum and one partectal pore.