Taxonomic revision and phylogeny of Dagetichthys and Synaptura (Soleidae)

We revised the genus Dagetichthys Stauch & Blanc, 1964, including the species traditionally included in the genus Synaptura, sensu Chabanaud (1928). The last revision of Synaptura was done by Chabanaud (1938). Subsequently, Synaptura cadenati Chabanaud (1948) was added to the group. We have examined type and non-type material and all original descriptions of the 46 nominal species of Synaptura. Meristic, morphometric, osteological and external characters were used to assess species validity and to build a cladogram depicting intrageneric and sister-group relationships. A recent study (Desoutter et al., 2001, Ichthyol. Res., 48) has established that Synaptura is not a valid soleid genus name. Cantor (1849) created this name as a replacement name for Brachirus Swainson, 1839, which he thought a homonym of Brachyurus, a mammal genus. Bleeker (1875) made a distinction between Synaptura and Brachirus, but without designation of a type species. Chabanaud (1928) then kept the name, designating Pleuronectes commersonnii Lacepede, 1802 as the type species for Synaptura. The International Code of Zoological Nomenclature states that such usages of a name and designations are incorrect. Synaptura Cantor then becomes a synonym of Brachirus. As a result of our analysis, we assigned the species previously assigned to Synaptura, sensu Chabanaud (1928) to Dagetichthys, a monotypic genus created for D. lakdoensis Stauch & Blanc, 1964. The six valid species now assigned to this broadened definition of Dagetichthys are monophyletic, based on eight derived morphological characters. Buglossidium luteum (Risso, 1810) was determined to be the sister group of Dagetichthys. The valid species of Dagetichthys are, from the most plesiomorphic to the most apomorphic, D. lakdoensis Stauch & Blanc, 1964, D. marginatus (Boulenger, 1900), D. lusitanicus (Brito Capello, 1868), D. commersonnii (Lacepede, 1802), D. albomaculatus (Kaup, 1858) and D. cadenati (Chabanaud, 1948). A biogeographical scenario based on the cladogram is provided along with an identification key to species.