Fragilaria candidagilae Almeida, C.Delgado, Novais & S.Blanco, type population

(Fig. 3)

Basionym: Fragilaria candidagilae Almeida, C.Delgado, Novais & S.Blanco in Delgado et al., Phytotaxa 231: 3, figs 2-39 (2015).

MORPHOLOGY

LM (Fig. 3 A-R)

Frustules in girdle view rectangular, solitary or two cells linked together (Fig. 48). Valves elliptic-lanceolate with convex or parallel margins in larger specimens, strictly convex margins in smaller valves. Valves occasionally irregularly shaped. Shoulders distinctly developed with clearly protracted, capitate to rostrate (in smaller specimens) apices. Valve dimensions (n = 25): valve length 11-23 µm, valve width 4-5 µm. Axial area very narrow linear, almost not widening towards the central area. Central area small, clearly asymmetrical due to absence or shortening of striae on one side, forming an asymmetrical fascia. Striae parallel throughout, becoming weakly radiate near the apices, 12-14 in 10 µm, often irregularly spaced. Areolae not discernible in LM.

SEM (Fig. 3 S-W)

Girdle composed of several open, perforated copulae (Fig. 3S). Large, irregularly shaped mantle plaques present on the mantle edge (Fig. 3S). Mantle striae continuing from the valve face till halfway the mantle edge (Fig. 3S). Striae uniseriate, composed of very small, rounded areolae (Fig. 3 T-U). Virgae between the striae very weakly raised to flat (Fig. 3V). One rimoportula present at one apex, in line with the before last stria at the apex (Fig. 3 T-V). Apical pore field present at both apices, relatively large, composed of up to five rows of relatively large, rounded to squarish pores (Fig. 3V). Spines never present. Internally, rimoportula distinctly present at one apex, superimposed on one of the final striae at the apex, weakly oblique (Fig. 3W).