Comparison of two new species of Mastogloia (Bacillariophyceae) with other small members of section Ellipticae Author Pennesi, Chiara Department of Life and Environmental Sciences, Polytechnic University of the Marche, via Brecce Bianche, 60131 Ancona, Italy Research and Collections, Canadian Museum of Nature, PO Box 3443, Station D, Ottawa, ON KIP 6 P 4, Canada Author Poulin, Michel Author Hinz, Friedel Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, D- 27570 Bremerhaven, Germany Author Romagnoli, Tiziana Department of Life and Environmental Sciences, Polytechnic University of the Marche, via Brecce Bianche, 60131 Ancona, Italy Research and Collections, Canadian Museum of Nature, PO Box 3443, Station D, Ottawa, ON KIP 6 P 4, Canada Author Stefano, Mario De Department of Environmental Sciences, 2 University of Naples, via Vivaldi 43, 81100 Caserta, Italy Author Totti, Cecilia Department of Life and Environmental Sciences, Polytechnic University of the Marche, via Brecce Bianche, 60131 Ancona, Italy Research and Collections, Canadian Museum of Nature, PO Box 3443, Station D, Ottawa, ON KIP 6 P 4, Canada text Phytotaxa 2013 2013-08-26 126 1 1 21 http://dx.doi.org/10.11646/phytotaxa.126.1.1 journal article 10.11646/phytotaxa.126.1.1 1179-3163 5085212 Mastogloia crucicula (Grunow) Cleve 1895 var. crucicula ( Figs 9–14 ) Basionym:— Orthoneis crucicula Grunow 1877 , p. 143 . Synonym: — Mastogloia quadrinotata Østrup 1904 , p. 149 , pl. 2 fig. 33. References:— Hustedt 1933 , p. 475, fig. 894; Hendey 1970 , p. 145, pl. 1, fig. 8; Ricard 1973 , p. 164, pl. 3, fig. 11, non fig. 12; Stephens & Gibson 1979a , p. 502, figs 17–24, 1980, fig. 42; Tomàs 1982 , pl. 4, fig. 9; Navarro 1983 , p. 120, figs 30, 31; Paddock & Kemp 1990 , figs 32, 63, 111, 134; Hein et al . 1993 , figs 16, 17, 2008, p. 63, pl. 36, figs 6, 7; John 1994 , p. 193, fig. 26; Witkowski et al . 2000 , p. 242, pl. 75, figs 3, 14, as M . ovulum . Material:— Sample from Siladen, Indonesia . SEM stub no. DISVAR-ANS7SP4. FIGURES 9–14. Mastogloia crucicula , SEM (DISVAR-ANS7SP4, Siladen, Indonesia). (9) External view of valve showing straight raphe branches and thin fascia; (10) External view of apex showing distal raphe ending with no terminal fissure; (11) Internal view of valve showing bilobed partectum ornamented with linear rows of fine pores; (12) Internal valve view showing one bilobed partectum (arrowhead) in each valve quadrant; (13) Internal view of tilted valve showing partectal pore (arrowhead); (14) External view of tilted valve showing areolae protected by siliceous vela with crescentic edges. SEM morphology:— The external valve surface shows a raphe-sternum that is transapically dilated at centre into a narrow fascia that extends almost up to the valve margins ( Figs 9, 12, 14 ). The raphe consists externally of two straight branches which are ending centrally and distally in expanded pores ( Figs 9, 10, 14 ). Internally, the raphe branches are straight and bordered by ribs which are ending at poles in distinct and slightly raised helictoglossae ( Figs 11–13 ). The transapical striae ( 18–25 in 10 µm ) are uniseriate and they vary from parallel at centre to radiate at apices ( Figs 9, 12, 14 ). The external openings of the areolae are rounded with a siliceous more or less crescentic edged-flap covering them (i.e., vola) and facing the valve margin, except for the first longitudinal row bordering the raphe-sternum where the areolae open to the raphe ( Figs 9, 10, 14 ). There are four, sometimes three, bilobed partecta ( 0.7–1.4 µm in width) which are located in each quadrant of the valve on the valvocopula ( Figs 12 , arrowhead, 13). Each partectum is ornamented with small pores arranged inwardly in parallel rows ( Fig. 11 ) and communicating with the exterior through an elongate partectal pore positioned opposite to the concave side of the partectal lobe ( Figs 13 , arrowhead, 14). Length: 10.2–29.1 µm ; width: 6.7–11.5 µm ( Table 1 ).