Revision of Partulidae (Gastropoda, Stylommatophora) of Palau, with description of a new genus for an unusual ground-dwelling species

Abstract

We describe a new stylommatophoran land snail of the family Partulidae from Palau. The new species has a combination of morphological and ecological characters that do not allow its placement in any existing partulid genus, so we describe a new genus for it. The new genus is characterized by a large (18–23 mm) obese-pupoid shell; smooth protoconch; teleoconch with weak and inconsistent, progressively stronger, striae; last half of body whorl not extending beyond the penultimate whorl; widely expanded and reflexed peristome; relatively long penis, with longitudinal pilasters that fuse apically into a fleshy ridge that divides the main chamber from a small apical chamber; and vas deferens entering and penial-retractor muscle attaching at the apex of the penis. Unlike all other partulids, the new species is strictly associated with rocks in contact with the ground. Comparing the other three Palauan species – currently assigned to Partula – to our new genus and to other partulids makes it clear that they require their own genus because their morphology is quite different from that of true Partula and from that of all other genera. Hence, we resurrect the name Palaopartula Pilsbry for these snails.

The tree snail on Rota Island, Northern Mariana Islands, long identified as Partula gibba (Partulidae), is a different species

“…Many taxonomic descriptions of partulid snails have emphasized reproductive anatomy, particularly differences in the male part of the reproductive tract, to differentiate species (Pilsbry 1909; Pilsbry and Cooke 1934 ; Kondo 1955 , 1968 ; Gerlach 2016 ; Slapcinsky and Kraus 2016 ). For this purpose, we obtained preserved specimens of Partula radiolata (lot nos.…”

“…To distinguish the new Rota Partula species from other extant species in the Mariana Archipelago, we paired our previously published phylogeny ( Sischo and Hadfield 2017 ) with anatomy of the male reproductive tract, the latter having been used extensively as a diagnostic trait for Partula species (Pilsbry 1909; Pilsbry and Cooke 1934 ; Kondo 1955 , 1968 , 1970 ; Gerlach 2016 ; Slapcinsky and Kraus 2016 ). Because we were not able to extract useful DNA from preserved tissue of Partula langfordi , we were unable to carry out molecular phylogenetics with that species.…”

HELIX: A data-driven characterization of Brazilian land snails

“…Analogously, the study of Slapcinsky and Kraus (2016) uses a morphometrical comparison to review the existing Palaus species and identify new morphological characteristics.…”

“…On the other hand, the shells, which are made of calcium carbonate, remain preserved long after. Accordingly, land snail shells are easily found in the wild and museums, and their investigation is one of the main sources in the characterization of such a class of gastropods [Ueta 1980, Slapcinsky andKraus 2016]. For instance, chemical analyses enable the extraction of climate, food, and genomics information, usually destroying (parts of) the shell in the process [Simone 2006, Hirano et al 2018.…”

“…A classical, non-invasive approach to label those shells is to (i) portray their physiology and then (ii) compare the collected measures against a golden pattern or reference [Simone 2006, Queiroz 2007, Slapcinsky and Kraus 2016. This morphometrical comparison process enables the fast identification of shells within collections and provides a rationale to find possible related species by similarity [Quenu andet.…”