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

Abstract

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 slow-moving 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 c 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.