Mastogloia matthaei Pennesi & Poulin, 2013

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 : 10

Mastogloia matthaei Pennesi & Poulin , sp. nov. ( Figs 37–44 , SEM; Figs 53–56 , LM)

Diagnosis:— Valvae ellipticae, 14.7–15.4 µm longae, 7.9–8.1 µm latae, rotundis apicibus. Extra raphe duobus ramis sinuosis constitutum, quod in parte media poris expansis, in parte autem distali poris leviter deflexis terminat; absunt terminales rimae. Interne raphe rectum est, quod in parte media elevato nodulo, in parte distali helictoglossa terminat. Transapicales striae uniseriatae (22–25 in 10 µm), parallelae in parte media, flexae et radiatae ad polos. Areolae quadriangulae in externa valva, at in interna longitudinales lineas formant. Partecta bilobata, apicaliter extensa, similia in mensura (1.0– 1.5 µm lata). Omne partectum in parte externa porum habet.

Description:— Valves elliptical, highly silicified, with rounded apices, 14.3–18.8 µm long and 7.9–10.1 µm wide ( Figs 37, 43 , 53–56 ). Externally, two sinuous raphe branches end in expanded central pores and in slightly deflected pores at poles; no terminal fissure present ( Figs 37–39, 43 ). Internally, two straight raphe branches ending in raised central nodule and helictoglossae at poles ( Figs 40, 41, 44 ). The uniseriate transapical striae (22–28 in 10 µm) are parallel at centre to curved and radiate at poles, forming a thickened irregular longitudinal pattern ( Figs 37 , arrowhead, 43). Externally, areolae are quadrangular and sunken on the valve surface, smaller in size at margin and absent on the mantle. Internally, areolae open through small rounded foramina aligned apically to form rather longitudinal rows ( Figs 40, 41, 44 ). Bilobed partecta, equal in shape and size (1.0– 1.5 µm in width), apically oriented and distributed along the whole length of the partectal ring up to the apex ( Figs 40 , arrowhead, 42, 44, 53, 55); no septum hiding the helictoglossa ( Figs 40, 42, 44 ). Each partectum is ornamented with small pores in parallel rows and opens to the outside through a partectal pore opposite to the concave side of the partectal lobe ( Fig. 44 ).

Holotype:— Circled specimen on slide CANA 86491 ( Canadian Museum of Nature , Ottawa, Canada). The holotype specimen is illustrated in Figures 55 and 56 . SEM images of the type material are Figs 37–44 .

Isotype:— Circled specimen on SEM stub no. DISVAR-ANS7SP46 (Department of Life Science and Environment, Polytechnical University of the Marche, Ancona, Italy).

Type locality:— INDONESIA. Siladen Island: in the Bunaken Archipelago (1°37'22.84"N and 124°43'30.81"E), Celebes Sea. Epiphytic on seagrass. Collected by Dr. Francesca Azzini, 1 October 2005 .

Etymology:— The specific epithet refers to the first author’s partner, Matteo Armatura.

Figures

FIGURES 37–44. Mastogloia matthaei, SEM, type material (SEM stub DISVAR-ANS7SP46, Siladen, Indonesia). (37) External view of valve showing sinuous raphe branches and thickened longitudinal stria pattern (arrowhead); (38) External view of central region showing proximal raphe endings and quadrangular areolae; (39) External view of apex showing distal raphe ending with no terminal fissure; (40) Internal valve view showing bilobed partecta (arrowhead) up to the apex and longitudinal stria pattern; (41) Internal view of central region showing raised central nodule; (42) Internal view of valve showing partecta with linear rows of fine pores; (43) External view of tilted valve showing longitudinal stria pattern with no areolae on mantle; (44) External view of tilted valve showing partectal pores.

FIGURES 53–60. Type specimens in pairs of the new species of Mastogloia showing first the striation and second the partectal ring, LM. (53–56) M. matthaei, CANA 86491, holotype specimen in Figs 55, 56; (57–60) M. stellae, CANA 86492, holotype specimen in Figs 59, 60.