Martinique

Martinique (mq)

Rivière Bras David

A. Eulin

E. Lefrançois

2019-4-16

61° 40' 15.6'' S ; 16° 11' 42'' E

-61.671 ; 16.195

LM : Frustules lanceolate to linear-elliptic in girdle view. Valves semi-elliptical to almost triangular, dorsal edge of valve convex, ventral edge slightly concave. The valve ends slightly protracted and curved towards the ventral edge of the valve. Valves 17.0–23.0 µm long and 6.5–8.0 µm in width. The raphe is located in a channel along the dorsal edge of the valve. Areolae visible with LM, ca. 16 in 10 µm. SEM : Externally, proximal raphe ends almost straight, slightly expanded to droplet shaped. Terminal raphe ends curved ventrally. Internal raphe endings are simple. Raphe opens internally into a canal with small round holes (portulae) lying between the major transapical ribs (Fig. 93). Striae coarsely punctate and strongly radiate. Externally, striae are composed of complex areolae: near the ventral side these are composed of two opposed ‘C’ shaped slits, and near the dorsal side of four opposed ‘C’ shaped slits, giving a flower-like aspect (Fig. 91). Discontinuous stria pattern with several missing areolae in the middle part of the valve (Fig. 89). Striae uniseriate, 16–18 in 10 µm. Primary fibular costae 3–4 in 10 µm with usually 4–6 striae between two costae (Figs 92, 93).