Two developmental stages of the micromorph rhynchonellid Tethyrhynchia mediterranea (Brachiopoda: Tethyrhychiidae) are described using scanning electron microscopy (SEM). They were found in niches of the mantle cavity of adult females, as T. mediterranea broods its offspring between the protecting valves of the shell. The developmental stages of T. mediterranea are very small (∼120 μm), but relative to adult body size of up to 1·2 mm in length they are larger than any other lecithotrophic brachiopod larva. Dispersal ability and phylogeography of T. mediterranea in the Mediterranean Sea is discussed.