Species of the genus <i>Gomphonema</i> from Haqlan hot springs, Iraq, with the description of two new species

This work presents a systematic account of the species of Gomphonema in Haqlan hot springs, Iraq. In diatom-rich material epiphytic on the aquatic plant Najas minor, 11 species belonging to Gomphonema were encountered, including two species new to science: G. brockiae sp. nov. and G. hadithaensis sp. nov. These species were described based on light and electron microscope observations. Gomphonema brockiae is a thermophilic and halophilic species, differentiated from its allied taxa by valve morphology and ultrastructure, including valve outline and size, stria density and areola shape. Gomphonema hadithaensis is characterized by its naviculoid shape and large size but can be distinguished from related taxa by its length/width ratio as well as stria density. A detailed morphological description of valve ultrastructure is provided for all species in this work. Eight of the currently identified Gomphonema species are new records for Iraq. This work is a documentation of diatoms present in a rapidly changing habitat due to severe shortage of freshwater supply to Iraq.