We report the first records of the poorly known crab spider Tmarus longicaudatus Millot, 1942 in Mauritania, Namibia and the United Arab Emirates (UAE). The new record in Mauritania extends the distribution of the species by almost 2750 km to the west from the closest and type locality in Niger. The new record in Namibia is 1000 km north of the closest locality in South Africa. New records in the UAE are more than 900 km east of the closest locality in central Saudi Arabia. Using all available records, we present the known distribution of the species and its climate-based predicted range, indicating a wide distribution in arid to semi-arid regions. Considering its wide expected distribution, extending throughout Africa and the Arabian Peninsula, integrative taxonomic studies are needed to clarify the species status of this masquerading spider.