Few and far apart: integrative taxonomy of Australian species of Gladiobela and Pagodibela (Conoidea : Raphitomidae) reveals patterns of wide distributions and low abundance

Abstract

The deep-sea malacofauna of temperate Australia remains comparatively poorly known. However, a recent influx of DNA-suitable material obtained from a series of deep-sea cruises has facilitated integrative taxonomic study on the Conoidea (Caenogastropoda:Neogastropoda). Building on a recent molecular phylogeny of the conoidean family Raphitomidae, this study focussed on the genera Gladiobela and Pagodibela (both Criscione, Hallan, Puillandre & Fedosov, 2020). We subjected a representative mtDNA cox1 dataset of deep-sea raphitomids to ABGD, which recognised 14 primary species hypotheses (PSHs), 9 of which were converted to secondary species hypotheses (SSHs). Following the additional examination of the shell and hypodermic radula features, as well as consideration of bathymetric and geographic data, seven of these SSHs were recognised as new to science and given full species rank. Subsequently, systematic descriptions are provided herein. Of these, five are attributed to Gladiobela (three of which are endemic to Australia and two more widely distributed) and two are placed in Pagodibela (one endemic to southern Australia and one widespread in the Pacific). The rarity of many ‘turrids’ reported in previous studies is confirmed herein, as particularly indicated by highly disjunct geographic records for two taxa. Additionally, several of the studied taxa exhibit wide Indo-Pacific distributions, suggesting that wide geographic ranges in deep-sea ‘turrids’ may be more common than previously assumed. Finally, impediments to deep-sea ‘turrid’ taxonomy in light of such comparative rarity and unexpectedly wide distributions are discussed.

Deep Downunder: Integrative taxonomy of Austrobela , Spergo , Theta and Austrotheta (Gastropoda: Conoidea: Raphitomidae) from the deep sea of Australia

“…While any inference of rarity will inevitably, to some extent, be an artifact of sampling, there is evidence that many turriform conoidean species are comparatively rare based on their scarcity in reasonably well‐sampled areas (Castelin et al, 2011). Bouchet et al (2009) noted this for the New Caledonian fauna and Hallan et al (2021) for some species of the deep‐sea genus Gladiobela . Theta microcostellata , T .…”

“…noted this for the New Caledonian fauna andHallan et al (2021) for some species of the deep-sea genus Gladiobela. Theta microcostellata, T. polita, Austrotheta crassidentata and Austrotheta wanbiri may therefore represent additional relatively rare species, as the regions in which they have been collected are comparatively well-sampled (MacIntosh…”

“…While it remains to be proven by means of molecular data that the material throughout this range is conspecific, the new records indicate that this may be a widespread species. There is growing evidence of wide distributions in several deep‐sea conoideans species (Hallan et al, 2021; Zaharias et al, 2020) and further sampling and systematics work will likely reveal additional widespread taxa. Criscione et al (2021) reported T. lyronuclea from Australia, although the topotypic Caribbean population has never been sequenced (Clarke, 1959).…”

“…While already alluded to by Bouchet and Warén (1980), recent findings also suggest that several deep-sea species may be unusually widespread geographically, with some taxa also occupying considerable bathymetric and geographic ranges (e.g. Hallan et al, 2021;Sánchez & Pastorino, 2020;Zaharias et al, 2020). With such complicating factors to their taxonomy, the notion that purely shell-based morphology can resolve the systematics of deep-sea turriform conoideans has therefore been largely abandoned in recent years, in favor of integrative approaches combining morphoanatomical, genetic and distribution data Hallan et al, 2020Hallan et al, , 2021Puillandre et al, 2009Puillandre et al, , 2017Zaharias et al, 2020).…”

“…Hallan et al, 2021;Sánchez & Pastorino, 2020;Zaharias et al, 2020). With such complicating factors to their taxonomy, the notion that purely shell-based morphology can resolve the systematics of deep-sea turriform conoideans has therefore been largely abandoned in recent years, in favor of integrative approaches combining morphoanatomical, genetic and distribution data Hallan et al, 2020Hallan et al, , 2021Puillandre et al, 2009Puillandre et al, , 2017Zaharias et al, 2020). Owing to their unique venom apparatus, an apomorphic character to the Conoidea (Puillandre et al, 2015), there is significant impetus to characterize turriform conoidean diversity in order to facilitate further studies on their venom diversity Gonzales & Saloma, 2014;Lopez-Vera et al, 2004;Puillandre, Koua, et al, 2012).…”