Resolution of the confused classification of some Miocene Nassariidae, and reappraisal of their paleobiodiversity on the French Atlantic seaboard (Gastropoda: Neogastropoda)

Abstract

The genus or subgenus Cyllenina previously included in the Cylleninae is diagnosed as a member of the subfamily Dorsaninae. Cyllenina appears related to the Early Miocene species Dorsanum aquensis. A lectotype is designated for Buccinum ancillariaeformis, the type species of Cyllenina. In addition, the Paratethys group Buccinum duplicatum (= Duplicatula) appears closely related to Dorsanum aquensis. It is also shown that the generic names Phos or Nassarius are incorrectly used for Nassa lineolata, an Early Miocene species Dorsanum. On the other hand, the Paleogene clade Keepingia is excluded from the Dorsaninae and treated here as an unassigned group of Nassariidae. An overview of the biodiversity (specific richness) is proposed for the Nassariidae of the French Atlantic coasts showing their rapid diversification during the Late Oligocene. For the Nassariinae, the highest richness is encountered during the Middle Miocene and for the Dorsaninae, during the Later Oligocene. The Cylleninae is represented by only one species, and like the Dorsaninae, it has not been recorded in the Late Miocene.

Mitogenomic phylogeny of Nassarius (Gastropoda: Neogastropoda)

“…acuticostus and Reticunassa is estimated around Miocene (36 MYA), indicating that the two clades share the same ancestor immigrated from the Atlantic. Within Nassarius , our results imply that these species diversified rapidly during the Miocene, as suggested by Galindo et al (), as well as Haasl () and Lozouet and Galindo () based on paleontological data.…”

Mitogenomic phylogeny of mud snails of the mostly Atlantic/Mediterranean genusTritia(Gastropoda: Nassariidae)

“…Our reconstructed time tree dates the origin of Nassariinae genera throughout the Oligocene, which is consistent with the fossil record (Lozouet & Galindo, 2015). A trend towards cooler conditions during the Oligocene (Zachos et al., 2001) is likely to have favoured temperate taxa (Uribe, Puillandre, et al., 2017; Uribe, Williams, et al., 2017).…”

“…Given the high frequency of the transition to lecithotrophy (together with its enhancing effects on extinction rates), it is likely that even if most living species of a taxon are included in a molecular phylogeny, the total number of independent transitions to direct development will be underestimated due to ignorance of what may have occurred in extinct lineages (Collin & Moran, 2018). Hence, fossil data appears necessary to testify and supplement the results of molecular data to improve the knowledge of the evolution of this important trait in the life cycle in the East Atlantic and Mediterranean nassariid gastropods (Lozouet & Galindo, 2015;Van Dingenen, Ceuleman, Landau, & da Silva, 2015). For instance, the West Mediterranean Pliocene species Nassarius martinelli is distinguished from the extant planktotrophic T. elata by its paucispiral protoconch, indicative of lecithotrophic development (Gili, 1992).…”

Returning to the roots: morphology, molecular phylogeny and classification of the Olivoidea (Gastropoda: Neogastropoda)

“…Nassarius arcularia (Linnaeus, 1758)] at the termination of growth, the parietal callus produces a very thick shield that extends over all the apertural side of the shell. In the fossil Cyllenina lucinensis (Landau & Marquet, 1999) from the Pliocene of Spain, the callus completely covers the shell, including the protoconch (Lozouet & Galindo, 2015). Although nothing is known about the mantle anatomy of such species, it is logical to suggest that the callus should be deposited by some equivalent of the posterior mantle lobe of Olivoidea, sometimes only at growth termination (N. arcularia) but sometimes during the entire life (C. lucinensis).…”