Petrodictyon gemma (Ehrenberg) D.G. Mann

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 : 144

Petrodictyon gemma (Ehrenberg) D.G. Mann in Round et al. (1990: 674) ( Fig. 108 )

References: Hendey 1964, p. 288, pl. 50, fig. 5, pl. 52, fig. 4; Krammer & Large-Bertalot 1988, p. 191, pl. 140, figs 1–3 (both as Surirella gemma (Ehrenberg) Kützing (1844: 62) ; Witkowski et al. 2000, p. 413, pl. 216, figs 8, 9.

Features: Length 70–92 μm, width 30–48 μm, striae 20–24 in 10 μm.

Description: Valves ovate to linear ovate with weakly convex margins. Fibulae connected to radiating transapical costae, which end in a very narrow axial area.

Remarks: Both P. gemma and P. patrimonii Sterrenburg (2001: 109) appear similar in valve outline and structure but areolae of the former species can be resolved under light microscope while it is invisible in the later (Sterrenburg 2001).

Ecology and Distribution: A widespread species both in marine and brackish water habitats. Previously reported from the Gulf ( Hendey 1970, Al-Yamani & Saburova 2011, Al-Handal 2009). Common in Basra corals.

Figures

FIGURES 103–110. Marine benthic diatoms in coral reefs off Basra. Fig. 103. Campylodiscus bicostatus, Fig. 104. Campylodiscus crebrecostatus, Fig. 105. Campylodiscus daemelianus, Fig. 106. Campylodiscus decorus, Fig. 107. Campylodicus imperialis, Fig. 108. Petrodictyon gemma, Fig. 109. Surirella fastuosa, Fig. 110. Campylodiscus neofastuosus.