Dressing down: convergent reduction of the mental disc in Garra (Teleostei: Cyprinidae) in the Middle East

In the Middle East, species of Garra are believed to have invaded the area in two independent waves from the Indo-Malayan biogeographic region. This hypothesis is based on the structure of the mental disc, a unique specialization of the lower lip, which is believed to be an adaptation to fast-flowing waters. While several species have such a mental disc, others completely lack a mental disc, being adapted to slowmoving water or to subterranean life. In this study, the phylogenetic relationships of Middle Eastern Garra species, including 16 described and 4 undescribed species, were analysed using mitochondrial cytochrome oxidase I sequences. The results are concordant with traditional hypotheses on two invasion events; however, these invasion events are independent from the presence, absence or shape of the mental disc. We postulate convergent reduction of the mental disc in 5–6 independent lineages of Garra in the Middle East.