Helicinae Rafinesque 1815

SYSTEMATICS OF THE HELICINAE

Our phylogenetic analyses strongly support the monophyletic origin of the Maghreb radiation of Helicinae in the Oligocene in the Maghreb region (Figs 3, 4). However, our analyses do not provide a robust resolution of the relationships within the Maghreb radiation. Based on these results, we propose to include all groups of the Maghreb radiation (Thebini, Otalini and Ereminini) in a single tribe, for which the oldest available name is Thebini (see Table 1 for an overview of classifications and newly proposed synonyms of the Maghreb radiation of Helicinae based on molecular phylogenetic analyses). Holyoak et al. (2020) proposed subdividing the Maghreb groups into three tribes: Thebini (in the strict sense only including Theba), Ereminini and Otalini (with a further subdivision into subtribes Otalina and Cantareusina Holyoak et al., 2020). However, Otalini in the sense of Holyoak et al. (2020) is neither statistically supported in their nor in our analyses (Figs 3 and 4). The western Alpine Macularia was weakly joined with the North African Eremina in the analyses of Holyoak et al. (2020), but was not assigned to any tribe by these authors. Contrary to the analysis of Holyoak et al. (2020), our analyses strongly support a sister-group relationship of Macularia and the Thebini (in the wide sense). Because of the wide geographic disjunction between the western Alpine Macularia and the primarily Maghrebian Thebini, we suggest a tribe Maculariini trib. nov. [type genus: Macularia Albers, 1850; diagnosis: Helicinae supported by the following apomorphic nucleotide substitutions (based on the alignment deposited in TreeBase under the study accession number 27632): 16S (position 267: T → A; position 283: A → T); only positions considered with data for all taxa and only changes with a consistency index of 1.00 given] to adapt the Linnean systematics of Helicinae to the new findings (ZooBank registration: https://zoobank.org/ urn:lsid:zoobank. org:act: 71BA5313-1FA2-48AE-8A3F-8ED8791EE4EE).

*According to Holyoak et al. (2020) the specimen determined as Massylaea massylaea (Morelet, 1851) by Bouaziz-Yahiatene et al. (2017) is a misidentified Eobania constantina (Forbes, 1838). † This placement was based on a misidentified sequence from GenBank attributed to Eremina desertorum (Forsskål, 1775) (AY841335; in fact Levantina).

This proposed classification closely mirrors the biogeographic history of the Helicinae. The Eastern Mediterranean Helicini diverged from the Western Mediterranean clade in the Eocene (Fig. 4). In the Late Eocene or Early Oligocene, the Western Mediterranean clade split into Allognathini in the Iberian Peninsula, Maculariini in the region of the future western Alps and Thebini on terranes probably including the Rif-Betic and Kabylies blocks that were at that time adjacent to south-western Europe, but later drifted south-westwards to form part of the Maghreb region (Rosenbaum et al., 2002). Further phylogenetic investigations are necessary to provide a better resolution within the tribes as a basis for more detailed biogeographic reconstructions.