On the phylogenetic position of Pseudophilomedinae within Sarsielloidea (Ostracoda, Myodocopida), with a description of one new Harbansus from Ningaloo Reef and redescription of H. paucichelatus from Yucatan

Abstract

Previous studies have suggested incongruence between current systematics and molecular phylogenies of Sarsielloidea, with a possible polyphyly of the family Philomedidae. Here, we provide molecular phylogenetic analyses based on 18S rDNA and 28S rDNA. The former includes five new sequences and 12 from the GenBank, and the latter two new and six sequences from the GenBank. We use three methods, maximum likelihood, maximum parsimony, and neighbor joining, and all reconstructed phylogenies support previously suggested polyphyly, indicating a closer relationship of the subfamily Pseudophilomedinae with one subfamily of Sarsiellidae than with the nominotypical subfamily of Philomedidae. Morphological characters that may be key indicators of the phylogenetic relationships between three Sarsielloidea families are discussed. We also describe the 21st representative of the Pseudophilomedinae genus, Harbansus Kornicker, (Smith Contrib Zool 260:75, 1978), Harbansus ningalooi n. sp., from the Ningaloo Reef, Western Australia. This is the first Harbansus reported from the Australian west coast and the second from the Australian coral reef systems. It differs from all other congeners by peculiar claw-like processes on the posterior infold. Most Harbansus species have relatively restricted distributions, except Harbansus paucichelatus (Kornicker, in Inst Mar Sci 5:195–300, 1958), which has also been postulated to represent a species complex. We present a detailed morphological redescription of this species, based on the freshly collected material from the Yucatan Peninsula, as well as four mitochondrial COI sequences. These become the first COI sequences of the entire superfamily Sarsielloidea available on the GenBank. To facilitate future identification, we include a key to species of Harbansus.