A new species of genus Provanna (Gastropoda, Abyssochrysoidea) from gas hydrate-bearing sediments of the northern South China Sea

Abstract

The genus Provanna (belonging to Superfamily Abyssochrysoidea) is a group of globally distributed gastropods commonly discovered in the deep-sea chemosynthetic environments. To date it is composed of 29 extant and nine fossil species and all of them seem to be endemic to vents, seeps or organic falls. Despite the increasing interest in cold seeps in South China Sea in recent decades, how this genus is distributed in this area is largely unknown. A new fossil species, Provanna dongshaensis sp. nov., collected from the hydrate-bearing sediments in the cold seep area of northern SCS, was studied. A basic morphological description together with the observation of shell microstructures was made, and a brief comparison to known Provanna species was summarized. The occurrence depths of this new species are consistent with the remarkable negative carbon isotope of carbonate layers, which mutually supports the relationship to the ancient seep. Such sedimentary samples from drilling cores may be potentially better materials for systematic research of deep-sea gastropods and other chemosynthesis fauna.