An application of morphological analysis and DNA barcoding to identify Ipnops from the Clarion-Clipperton Zone (CCZ) as I. meadi Nielsen, 1966 with notes on other species of the genus (Aulopiformes: Ipnopidae)

Abstract

Although Ipnops specimens are relatively common in the Clarion-Clipperton Fracture Zone (CCZ), an area targeted for potential future deep-sea mining, a reliable species identification has not yet been possible due to the lack of a captured specimen. In April 2012, an Ipnops specimen was caught for the first time from the eastern CCZ during an exploration cruise of the BGR. Species identification of this specimen was performed using a comparative application of morphological analysis and DNA barcoding and resulted in its clear assignment to Ipnops meadi Nielsen, 1966. Of the 23 compared morphological characters, 22 are inside the ranges available for I. meadi. Molecular analyses show a sequence distance of 0.76% divergence to an Ipnops specimen collected off Hawaii, close to the CCZ and also within the known geographical distribution range of I. meadi. The additional study of five specimens of I. meadi from the Arabian Sea has extended the previously known range of the following morphological characters of this species: gill rakers on anterior arch (17–21), head length (17.6–24.0 % SL), upper jaw length (10.7–14.0 % SL), maximum width of eye-plates (7.8–9.8 % SL), preanal length (58.8–79.0 % SL), and predorsal length (34.5–40.5 % SL). Ipnops specimens deriving from Australian waters could not be clearly assigned with confidence to one of the valid Ipnops species based on current morphological and molecular analyses. It seems possible that at least one previously undescribed Ipnops species occurs in Australian waters and further work is required on the genus to resolve uncertainties.