Revision of the family Sargassaceae (Fucales, Phaeophyceae) from Kuwait (Arabian / Persian Gulf, NW Indian Ocean) based on analysis of morphology and ITS2 sequences

This article investigates the species of the family Sargassaceae present in Kuwait, analyzing nuclear ribosomal internal transcribed spacer 2 (ITS2) sequences of 67 individuals collected in 2018–2020. Morphological characterization and DNA barcoding confirmed the presence of eight taxa that belong to Sargassaceae. Five species belong to the genus Sargassum, while three other taxa, namely Sirophysalis trinodis, Hormophysa cuneiformis, and Polycladia myrica, belong to other genera. For the latter species, there was no ITS2 sequence available so far. As for Sargassum species, previous records based on phenotypic identifications were only confirmed for a minority of species. Based on 100% sequence identity with records from other regions, we recognize S. aquifolium, S. ilicifolium var. acaraeocarpum, S. yinggehaiense, and one still unclear species (Sargassum sp.). According to the sequences, the fifth and most common Sargassum species in Kuwait, previously identified as S. asperifolium, is S. carpophyllum. However, the ITS2 sequence of this entity did not show a perfect match with any S. carpophyllum specimen so far sequenced. The comparatively limited diversity of Sargassum in Kuwait may be due to the prevailing extreme environmental conditions, in particular large temperature amplitude between +14 °C in winter and +37 °C in summer.