Mesalia Gray, 1847

Harzhauser, Mathias & Landau, Bernard, 2019, Turritellidae (Gastropoda) of the Miocene Paratethys Sea with considerations about turritellid genera, Zootaxa 4681 (1), pp. 1-136 : 100

Genus Mesalia Gray, 1847

Type species: Turritella mesal Deshayes, 1843 (= Le Mesal Adanson, 1757; non available pre-Linnaean name); subsequent designation by Reeve (1849: 236). Recent, Senegal, Western Africa.

Remarks. There is quite some confusion in the literature about the publication date of Mesalia (e.g. Gray 1840, 1842 or 1847) and its type species ( Turritella mesal Deshayes, 1843 versus Turritella brevialis Lamarck, 1822 ). Indeed, the genus Mesalia was listed as nomen nudum by Gray (1840). In the 44 th edition of his ‘ Synopsis ’ Gray (1842: 61) included a short description (‘slightly twisted inner lip’) but did not provide any species names (see also discussion in Smith 1915). This was done by Gray in 1847, when he listed the extant West African Turritella mesal Deshayes, 1843 and the Eocene Turritella sulcata Lamarck, 1804 , from the Paris Basin, as species placed in Mesalia . Thus, no type designation is found in Gray (1847), although it is obvious that he would have chosen the extant T. mesal . Shortly afterwards, the type was fixed by Reeve (1849), referring to Le Mesal of Anderson (1757). Unfortunately, he considered Turritella mesal Deshayes, 1843 as junior synonym of Turritella brevialis Lamarck, 1822 and therefore, named this species as type species. Currently, both taxa are treated as separate species ( Marche-Marchad 1960; MolluscaBase 2018c) [note that Turritella brevialis sensu Reeve (1849) is a misidentification of Mesalia mesal ( Marche-Marchad 1960; MolluscaBase 2018c)]. Consequently, the type species of Mesalia is Turritella mesal Deshayes, 1843 in accordance to ICNZ Article 69.2.2 that states: ‘ If an author designates as type species a nominal species that was not originally included and if, but only if, at the same time he or she places that nominal species in synonymy with one and only one of the originally included species that act constitutes fixation of the latter species as type species of the nominal genus or subgenus.’

Recent molecular data confirmed the monophyly of Mesalia and revealed a large genetic distance from Turritellidae (Anderson et al. 2018; Brendan M. Anderson, pers. comm., January 16 th 2019). Morphologically, Mesalia is distinguished from Turritella s.s. by its less elongated shape, the blunt apex, the sinuous outer lip and the simple concave, shallow lateral sinus with low angle and the slightly prosocyrt basal sinus ( Marwick 1957; Landau et al. 2004; Gofas 2011). A strongly concave columella with a weak fold between columellar lip and parietal lip is another distinguishing feature ( Marwick 1957). No inner lirae are observed in Paratethyan species.