Eocene handfishes from Monte Bolca, with description of a new genus and species, and a phylogeny of the family Brachionichthyidae (Teleostei: Lophiiformes)

摘要

The family Brachionichthyidae, commonly known as the handfishes, is a small group of lophiiform fishes, the living species of which are restricted in distribution mostly to shallow temperate and subtropical waters of Tasmania and southern and eastern Australia. Despite their narrow present-day distribution, and the extreme rarity of lophiiforms in the fossil record, handfishes are well represented in the Eocene of Monte Bolca, Italy. A revision of the known fossil material shows the presence of two fossil species in two monotypic genera, Histionotophorus and Orrichthys gen. nov. Diagnoses of the family Brachionichthyidae, the two fossil genera, as well as two recognized extant genera Brachionichthys and Sympterichthys are provided. An osteological analysis of Histionotophorus bassani revealed many new features as well as reinterpretations of some previously described skeletal parts. A phylogenetic analysis of brachionichthyid genera and representatives of the antennarioid families Antennariidae, Tetrabrachiidae, and Lophichthyidae, using 36 morphological characters, strongly supported monophyly of brachionichthyids and antennarioids, the former taxon representing the sister group of the other families of the latter. Within the Brachionichthyidae, the two extant genera Brachionichthys and Sympterichthys form a species pair, as do the extinct genera Histionotophorus and Orrichthys gen. nov. Biogeographical considerations suggest that the present geographical range of handfishes can be considered a residual distribution of a temporally and spatially dynamic range shift