Mapping the missing branch on the neogastropod tree of life: molecular phylogeny of marginelliform gastropods

Abstract

Marginelliform gastropods are a heterogeneous and diverse group of molluscs encompassing over 1,600 living species, among which are the smallest known neogastropods. The relationships of marginelliform gastropods within the order Neogastropoda are controversial, and the monophyly of the two marginelliform families the Marginellidae J. Fleming, 1828 and the Cystiscidae Stimpson, 1865, remains unconfirmed. DNA sequence data have never been used to assess the relationships of the marginelliform gastropods, making this group the only major branch missing in our current understanding of the neogastropod tree of life. Here we report results of the first multilocus phylogenetic analysis of marginelliform gastropods, which is based on a dataset comprising 63 species (20 genera) of Marginellidae and Cystiscidae, and a wide range of neogastropod lineages. The Marginellidae and Cystiscidae form a moderately supported clade that is sister to the family Volutidae. Marginellona gigas appears to be sister to all other marginelliforms. The subfamily Marginellinae was recovered as a well-supported clade, and good resolution of this part of the tree makes it possible to propose amendments to the family-level classification of the group. The relationship between Granulina and other marginelliforms could not be resolved and requires further study. Due to poor resolution of basal relationships within the Marginellidae–Cystiscidae clade, the monophyly of the Cystiscidae was neither confirmed nor convincingly rejected. The shell morphology of most marginellid and cystiscid genera is taxonomically not very informative but, nevertheless, of the traditionally recognized genera only Gibberula and Dentimargo were shown to be polyphyletic. Although a comprehensive systematic revision of the group requires more extensive taxonomic sampling (e.g. with better representation of the type species of nominal genus-group names), our results support the superfamily Volutoidea, comprising four families (Volutidae, Cystiscidae, Marginellidae and Marginellonidae), with the placement of the Granulinidae uncertain for the time being.

Neogastropod (Mollusca, Gastropoda) phylogeny: A step forward with mitogenomes

“…The five firsts phylogenies were based on few mitochondrial and nuclear genes (typically: cox-1, 16S, 12S, 28S), and for each of them the focus taxon is indicated; the five others were based on mitogenomes; the last one corresponds to the phylogeny on the Figure 1. Superfamilies for which the monophyly is supported in several phylogenies (Conoidea, Tonnoidea, Buccinoidea except Belomitridae) are not detailed at the family level included here, might not be closely related to the other Buccinoidea, as suggested by Abdelkrim et al (2018) and Fedosov et al (2019). Furthermore, the relationships between the Buccinoidea families are not supported, and sometimes contradict previously published results: for example, the Columbellidae are sister to the Colubrariidae in the MrBayes AA tree with high support, whereas they were found embedded within the Nassariidae in Kantor et al (2021).…”

“…Within the Buccinoidea, the Belomitridae and Dolicholatiridae have been shown to be sister to the rest of the Buccinoidea in Kantor et al (2021), but the Belomitridae were not recovered as sister to the other Buccinoidea in Abdelkrim et al (2018). The four families of marginellids (Cystiscidae, Granulinidae, Marginellidae and Marginellonidae) have been shown to be monophyletic and most probably sister to the Volutidae (thus forming the Volutoidea, excepted Cancellariidae) in Fedosov et al (2019); however, this remains to be confirmed in a large-scale phylogeny of neogastropods. The likely nonmonophyletic Turbinelloidea probably constitutes the main gap in the neogastropod sampling, since several published molecular phylogenies (including the present one) do not support its monophyly, although three out of five families (Columbariidae, Ptychatractidae, Volutomitridae) have almost never been included in a molecular phylogeny targeting the Neogastropoda.…”

“…The current state-of-the-art of the neogastropod classification, as provided in WoRMS (WORMS, 2018, consulted on the 14 March 2022), is mostly based on the molecular phylogenies published in the last 10 years and the associated taxonomic revisions. Thus, the superfamilies Conoidea (Abdelkrim et al, 2018;Bouchet et al, 2011;Kantor et al, 2012;Puillandre et al, 2011;Yang et al, 2021), Buccinoidea (Couto et al, 2016;Galindo et al, 2016;Kantor et al, 2021;Oliverio & Modica, 2010), Mitroidea (Fedosov et al, 2015(Fedosov et al, , 2018Kantor et al, 2014), Olivoidea (Kantor et al, 2017), Muricoidea (Barco et al, 2010), the families Cancellariidae (Modica et al, 2011), Costellariidae (Fedosov et al, 2015(Fedosov et al, , 2017 and the marginellids (Cystiscidae, Granulinidae, Marginellidae, Marginellonidae -Fedosov et al, 2019) have been found monophyletic, and the family-and/or genus-level classifications have been deeply revised. In some cases, the reconstructed phylogenetic relationships necessitated the introduction of a large number of new family-level taxa, in particular within the Conoidea and Buccinoidea, that switched from 7 and 9 families, respectively, to 17 and 20.…”

The genus Sveltia (Gastropoda, Cancellariidae) in the Atlantic Pliocene of Iberia with a new species from the Cenozoic Mondego Basin of Portugal

“…Bouchet et al (2017, p. 379) synonymized Cancellarioidea Forbes and Hanley, 1851, with Volutoidea Rafinesque, 1815. However, the most recent molecular phylogeny of Fedosov et al (2019, fig. 2) suggests indeed that Cancellariidae are not nested with the rest of the Volutoidea, hence Cancellarioidea is a valid superfamily.…”

Vexitoxins: a novel class of conotoxin-like venom peptides from predatory gastropods of the genus Vexillum

“…Its acquisition was invariantly accompanied by a modification or a complete loss of vL (Ponder 1973; Kantor & Fedosov 2009; Fedosov et al 2017), thus effectively setting the stage for venom production and delivery. Several lines of evidence suggest that each neogastropod lineage possessing such derived morphology uses venom to subdue and kill the prey (Maes & Raeihle 1975; Olivera et al 2014; Fedosov et al 2019).…”