Pleurosigma strigosum Smith (1852: 7)

Al-Handal, Adil Y., Thomas, Evan W. & Pennesi, Chiara, 2018, Marine benthic diatoms in the newly discovered coral reefs, off Basra coast, Southern Iraq, Phytotaxa 372 (2), pp. 111-152 : 131

Pleurosigma strigosum Smith (1852: 7) ( Fig. 63 )

References: Hendey 1964, p. 246, pl. 26, fig. 7; Krammer & Lange-Bertalot 1988, p. 294, pl. 113, figs 1,2).

Features: Length 122–138 μm, width 20–26 μm, oblique striae 18–22 in 10 μm, crossing each other by an angle of 60 o or slightly larger.

Description: Valves elongated, sigmoid-lanceolate in shape with protracted apices. Raphe central, sigmoid, slightly eccentric towards apices. Axial area narrow, central nodule small and rounded. Striae appear in equidistant oblique and transverse row. Oblique striae crossed each other in 60 o angle.

Remarks: very similar to P. angulatum (Quekett) W. Smith (1852: 7) but can be separated by having larger striae angles and absence of terminal perpendicular striae as well as valve margins are more smoothly curved.

Ecology and Distribution: A widely distributed marine species. Previously reported from the Gulf (Al-Yamani & Saburova 2011). Frequent in Basra corals.

Figures

FIGURES 62–74. Marine benthic diatoms in coral reefs off Basra.Fig. 62. Pleurosigma diverse-striatum, Fig. 63. Pleurosigma strigosum, Figs 64, 65. Plagiotropis lepidoptera, Fig. 66. Stauroneis sp., Fig. 67. Amphora arcuata, Fig. 68. Amphora arenaria, Fig. 69. Amphora cf. commutata, Fig. 70. Amphora cingulata, Fig. 71. Halamphora coffeaeformis, Fig. 72. Halamphora costata, Figs 73,74. Amphora graeffeana.