Trochulus hispidus

Proćków, Małgorzata, Mackiewicz, Paweł & Pieńkowska, Joanna R., 2013, Genetic and morphological studies of species status for poorly known endemic Trochulus phorochaetius (Bourguignat, 1864) (Gastropoda: Pulmonata: Hygromiidae), and its comparison with closely related taxa, Zoological Journal of the Linnean Society 169 (1), pp. 124-143 : 137-138

publication ID	https://doi.org/ 10.1111/zoj.12048
persistent identifier	https://treatment.plazi.org/id/039A8794-FFDB-FFFC-FF40-FBD6C4C1BB25
treatment provided by	Marcus
scientific name	Trochulus hispidus
status

Treatment

WITH T. HISPIDUS View in CoL AND T. PLEBEIUS

The shell size of T. phorochaetius examined in this study stayed in accordance with those given by Winter (1990), although measurements alone were not sufficient for reliable differentiation ( Table 2). Our results showed that T. phorochaetius was very similar to T. plebeius , whereas both differed from T. hispidus . Umbilicus relative diameter (U/D) discriminated T. hispidus from the other two taxa, although the differentiation from T. plebeius was less distinct than from T. phorochaetius . This character was less variable in T. phorochaetius than in T. hispidus : 0.07–0.14 and 0.16–0.27, respectively ( Table 2). The conchological similarity of T. phorochaetius , T. plebeius and T. sericeus has already been mentioned by Winter (1990), who identified many characters possibly specific for T. plebeius from Belgium, Luxemburg, and southern Germany, i.e. smaller shells with about the same number of whorls, a higher spire, and often more narrow umbilicus. These shells also possessed a dense cover of curved hairs, which were clearly shorter and finer than in T. phorochaetius . In contrast to this study, we have found no such differences, except for hair morphology. Hair length could be used to distinguish T. phorochaetius , but with caution; admittedly, hairs were not as long as in T. villosus or even T. villosulus ( Fig. 3E–F View Figure 3 ), but were still conspicuous compared with T. plebeius or T. hispidus ( Fig. 3C, G View Figure 3 ). Furthermore, one of the characters quoted in the diagnosis of T. phorochaetius was short, whitish, and weakly lost hairs (‘petits poils blancs, courts, recourbés et peu caducs’; Bourguignat, 1864). Thus, in this study we confirm that hair durability is distinctive for T. phorochaetius , similar to T. villosus and T. villosulus ( Proc´ków, 2009). However, when only weathered shells with no hairs are available, recognizing these species is difficult.

The ratio of umbilicus minor to its major diameter (u/U) appeared to be another significant character, which may help in distinguishing T. phorochaetius from T. plebeius . Indeed, in the respective populations, the mean values differed among both species, but their ranges still overlapped ( Fig. 5 View Figure 5 ), reaching 0.71–1.0 in T. phorochaetius and 0.64–0.81 in T. plebeius . However, some morphological tendencies could be noticed, i.e. the umbilicus in T. phorochaetius seemed to be round, whereas in T. plebeius the umbilicus was more oval. The most distinctive features distinguishing three Trochulus morphospecies are presented in Table 5. Differentiation of T. phorochaetius from both T. plebeius and T. hispidus was impossible on the basis of the anatomical characters examined. No constant trait that would be useful for the reliable identification of the species has been found. Winter (1990), describing the genital system of T. phorochaetius , did not give the measurements but only referred to the figures of T. ‘plebeia’ ( Schileyko, 1978) and measurements of T. ‘sericea’ ( Klöti-Hauser, 1920). He particularly pointed out the distinction of T. phorochaetius from the East German and Czechoslovakian specimens of T. ‘plebeia’ examined by Schileyko (1978), and simultaneously showing its resemblance to the Swiss T. ‘sericea’ investigated by Klöti-Hauser (1920). Likewise, our studies did not reveal anatomical differences between T. plebeius and T. hispidus , possibly suggesting that they are not different species. As genital morphology is strongly associated with mating success in land snails ( Gómez, 2001), our results may provide additional evidence for a lack of reproductive isolation and thus the ability to crossbreed (see later in the Discussion). In agreement with this, there were two significant clades containing COI sequences of both T. plebeius and T. hispidus from the same countries: Great Britain and Poland, respectively ( Fig. 9 View Figure 9 ). Similarly, laboratory studies of the Sicilian helicid Marmorana showed that snails with different shell shapes (i.e. flat keeled versus globular) mated and produced viable offspring ( Rensch, 1937), and that the different populations had similar genitalia ( Fiorentino et al., 2008). Furthermore, neither substantial sexual isolation barriers nor genital differentiation were found between