Phylogeny and diversity of Timiriaseviinae ostracods (Podocopida, Cytheroidea) with description of one new species from arid Western Australia

Abstract

Gomphodella De Deckker, 1981 belongs to the subfamily Timiriaseviinae, and it inhabits almost exclusively subterranean waters of Western Australia. We describe the ninth species of the genus, G. alexanderi sp. nov., from bore-holes in the Pilbara region. The species is closely related to G. yandii Karanovic, 2009 and G. quasihirsuta Karanovic, 2009, but can be distinguished by its shell morphology, appearance of the hemipenis, and chaetotaxy of the antenna. We also report on G. yandii and G. cf. martensi Karanovic, 2009, collected sympatrically with the new species, indicating some new characters not mentioned in the original descriptions. We show for the first time that Gomphodella has an inverse lophodont hinge, instead of a lophodont one as previously believed. The significance of the hinge structure, sulci, and other shell characters in the systematics of Timiriaseviinae are discussed. In addition, the posterior extension on the female body, the so-called 'forked organ', is here reported for the first time in the genus Gomphodella. Because these characters provide a new insight into the phylogenetic relationships of Timiriaseviinae we performed two cladistic analyses: one including only nine genera with living representatives, the other including 17 genera. They resulted in one and 23 equally parsimonious trees respectively. Inclusion of the fossil taxa significantly changes the tree topology, but on both trees the Gondwanan lineage, Cytheridella Daday, 1905/Gomphocythere Sars, 1924/Gomphodella is strongly supported, as well as a close connection between the South American semi-terrestrial and some fossil genera. Another well-supported clade is formed by the genera Kovalevskiella Klein, 1963, Frambocythere Colin, 1980 and Rosacythere Colin, 1980. Maps of distribution of Recent genera and geological age of Timiriaseviinae are also presented here.