The brachiopod Argyrotheca cuneata (Brachiopoda: Megathyrididae) is reported for the first time from the southern coast of Türkiye. Twenty-three complete specimens were found in samples of shell grit taken from depths less than 5 m. The findings suggest that A. cuneata may be a common brachiopod species in shallow nearshore habitats along the southern coasts of the country. Widths of the largest and the smallest specimens were 3.7 mm and 0.71 mm, respectively. A comparison of shell dimensions of all specimens indicate an allometric change in the shape of A. cuneata during growth from being longer than wide to wider than long. The protegula preserved on the smallest specimens are described and illustrated possibly for the first time for this species.
