Mastogloia ovalis Schmidt 1893

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 ovalis Schmidt 1893 in A. Schmidt et al. 1874 –1959 ( Figs 21–28 )

References:— Schmidt et al. 1874 –1959, pl. 175, fig. 30; Hustedt 1933, p. 474, fig. 893; Ricard 1973, p. 168, pl. 1, fig. 6, 1975, p. 53, pl. 2, figs 12, 13; Montgomery 1978, pl. 141, fig. F, as M. ovulum ; Stephens & Gibson 1979a, p. 505, figs 33–40, 1979b, fig. 5; Navarro 1982, p. 40, pl. 26, fig. 3; Tomàs 1982, figs 16, 17; Paddock & Kemp 1990, figs 31, 113, as M. ovata ; Witkowski et al. 2000, p. 255, pl. 75, figs 11–13; Hein et al. 2008, p. 69, pl. 40, fig. 6.

Material:— Sample from Siladen, Indonesia. SEM stub no. DISVAR-ANS2SP17.

SEM morphology:— The raphe consists externally of two straight branches that are ending in expanded central and terminal pores ( Figs 21, 22, 28 ). Internally, the raphe branches are bordered by slightly elevated ribs, with a raised central nodule and helictoglossae at poles ( Figs 24, 25, 27 ). The transapical striae (18–26 in 10 µm) are uniseriate and they are radiate at centre to curved and radiate at the poles crossed by slightly quincunx pattern ( Figs 21, 28 ). Externally, the areolae are rounded and they are covered by distinct tonguelike vola with horseshoe-shaped edges; none are present on the mantle ( Figs 22, 23, 28 ). Each side of the valvocopula bears between two to eight bilobed partecta similar in shape and size (1.0– 1.6 µm in width), which are distributed along most of the length of the partectal ring but without reaching the apex ( Figs 24 , arrowhead, 27). Each partectum is clearly differentiated by a distinct indentation between them ( Figs 24, 26 ) and is ornamented on its surface with small pores in parallel rows ( Fig. 26 ). Each partectum opens to the outside through an elongate partectal pore positioned opposite to the concave side of the partectal lobes ( Figs 23, 27 , arrowheads, 28). Length: 10.5–24.0 µm; width: 6.4–11.6 µm ( Table 1).

Figures

FIGURES 21–28. Mastogloia ovalis, SEM (DISVAR-ANS2SP17, Siladen, Indonesia). (21) External view of valve showing straight raphe branches; (22) External view of central region showing proximal raphe endings; (23) External view of tilted valve showing partectal pore (arrowhead); (24) Internal valve view showing well-marked bilobed partecta (arrowhead); (25) Internal view of central region showing proximal raphe endings; (26) Internal view of valve showing partecta with linear rows of fine pores; (27) Internal view of tilted valve showing partectal pores (arrowhead); (28) External view of tilted valve showing rounded areolae covered by tongue-like vela with horseshoe-shaped edges.