Sulcatae

Lobban, Christopher S., 2015, Benthic marine diatom flora of Guam: new records, redescription of Psammodictyon pustulatum n. comb., n. stat., and three new species (Colliculoamphora gabgabensis, Lauderia excentrica, and Rhoiconeis pagoensis), Micronesica 2015 (2), pp. 1-49 : 8-9

Section Sulcatae .

Ref. illus.: Peragallo & Peragallo 1897 –1908, pl. 6, fig. 3; Hustedt 1931 –1959, fig. 989; Ricard 1974, p. 3(21), fig. 7; Ricard 1975, figs 32–35; Paddock & Kemp 1990, fig. 20c; Witkowski et al. 2000, pl. 80, figs 7, 8

Samples: GU44I-2, GU44K-6, GU52Q-10a, GU66A-5, GU66F-8

Dimensions: Length 30–58 µm, width 14–19 µm; striae 22–24 in 10 µm

Diagnostics: Elliptical-lanceolate to rhombic-lanceolate valves with strong longitudinal lines and narrow partectal rings with square to apically rectangular partecta. Outer raphe is strongly sinuous and the inner straight; central endings straight.

Comments: The species name refers to the strong longitudinal lines, which mark the borders of the pseudoconopeum; a thin dark line marking the joint in the pseudoconopeum can sometimes be seen in LM and is clear in SEM ( Figs 77, 78, arrows). Our stria densities are higher than those in Peragallo & Peragallo (1897 –1908) (15–16 in 10 µm) and Hustedt (1931 –1959) (16–20 in 10 µm). Montgomery (1978, pl. 138, figs A–E, pl. 139, figs C, D) has exterior SEMs labeled as M. quinquecostata , but they all show specimens with true conopea, open along the side, in contrast to Paddock & Kemp’s (1990) illustration. The partecta shown in Witkowski et al. (2000) do not match those in Hustedt’s (1931 –1956) drawings.