Sparse assemblages of palynomorphs have been collected from the glacially derived Khalaqah Member of the Kooli Formation in northwest Yemen. The presence of common Leiosphaeridia and Deusilites tentus, indeterminate taeniate bisaccate pollen, and such species as Plicatipollenites malabarensis, Verrucosisporites sp., Brevitriletes cf. B. cornutus, and Cristatisporites cf. C. crassilabratus, suggest an age range from Late Carboniferous to Early Permian. Previous workers have considered that a small variation in wall thickness could be used to separate Deusilites tenuistriatus Gutierrez et al. 1997 from the Early Permian of Brazil and Argentina from Deusilites tentus Hemer and Nygreen 1967. The evidence from the Kooli Formation, of highly variable wall thicknesses within a single population of Deusilites suggests that the two species should not be separated and that D. tenuistriatus is a junior synonym of D. tentus.

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