Charpentieria itala: subspecies, species, superspecies
Hartmut Nordsieck (V.2021)
I. Introduction and history
In the revision of the Charpentieria species from the southern limestone Alps (Nordsieck 1963: 174-190, as Delima) I tried to describe the intraspecific diversity of C. itala (G. von Martens 1824) by a subdivision of the species of that region into several subspecies. These are (from W to E) C. i. albopustulata (Cristofori & Jan 1832), C. i. latestriata (Küster 1850), C. i. rubiginea (Rossmässler 1836), and C. i. serravalensis (H. Nordsieck 1963), besides, as transitional forms within C. i. albopustulata, but later on treated as subspecies, C. i. braunii (Rossmässler 1836) and C. i. baldensis (Charpentier 1852) [already described by Strobel (1851: 25)]. A complex of forms from the same region which in shell morphology and ecological preferences are similar to the related species C. stenzii (Rossmässler 1836), but in genital morphology largely correspondent with C. itala and in part connected with it by transitional forms, was included in the latter as so-called stenzioid subspecies (Nordsieck 1963: 171-173, 181-187): C. i. clavata (Rossmässler 1836), C. i. variscoi (Pini 1883), C. i. balsamoi (Strobel 1850), C. i. lorinae (Gredler 1869). Later on, because of its semispecies character, that complex has been separated as species C. clavata (Nordsieck 1979: 259). In the 1963 paper the subspecies of C. itala from the remaining distributional range (Monti Berici and Colli Euganei, Provence, Maritime and Ligurian Alps, northern and central Apennines) were not considered. The related species C. dyodon (Studer 1820) from Piedmont was not treated either, because at this time its close relationship to C. itala was not known. Zilch (1972), in a type catalogue of the Delimini, has also listed the subspecies of C. itala outside the southern Alps: C. i. itala from Monti Berici and Colli Euganei, and C. i. nigra (Issel 1866) and C. i. punctata (Michaud 1831) from the remaining range.
Several Italian authors called in question the proposed subdivision of C. itala into subspecies, with the following arguments:
Giusti & Mazzini (1971: 294): „Sulla scorta delle sue descrizioni [Nordsieck 1963] abbiamo provato a determinare alcuni materiali dell‘ Italia settentrionale, tuttavia, senza riuscirci mai con sicurezza. Tanto variabili sono i caratteri conchiliologici …“
Boato et al. (1985: 312): C. itala cfr. punctata: „…, sia questa, che le numerose altre che normalmente si includono nella C. itala sono spesso variabili e poco definite“.
Manganelli et al. (1995: 47): „Molte delle entità sottospecifiche convalidato da Nordsieck (1963 …) e da Zilch (1972 …) qui riportate appaiano di validità dubbia“.
These statements, however, are only opinions, not substantiated by further investigations.
Therefore, for this chapter the shell characters, on which the subspecies division of C. itala was based, have been checked once more, and the revision of 1963 was supplemented by the inclusion of the forms from beyond the southern Alps and of C. dyodon from Piedmont. The stenzioid subspecies of C. itala = C. clavata and the transitional subspecies C. i. allatollae (Käufel 1928) were not considered in this revision, because new results could not be expected. The examined shell material of C. itala has been augmented by a third (from 350 samples for the 1963 paper to 460 for this chapter), and 25 samples of C. dyodon have been included. The material is deposited in the collection of the Forschungsinstitut Senckenberg (SMF) and in my own collection (deposited mainly in the Staatliches Museum für Naturkunde Stuttgart).
It resulted that the most important characters, those of lunellar and clausilium plate, are not at all too variable and are therefore suited for the definition of subspecies. Obviously, these characters were not considered or not understood by the named authors (because the paper was written in German). In the following they are once more described and figured.
1. Character analysis:
The lunellar of C. itala (Fig. 1) consists of (posterior) upper palatal plica, lunella and posterior lower palatal plica. An anterior upper palatal plica and an anterior lower palatal plica (= basalis) are absent. The posterior lower palatal plica is named subclaustralis; it is connected with the lunella by an obtuse or nearly right angle. A further posterior lower palatal plica, the lowest one, is named sulcalis. It is in part weakly developed; as a rule, it is not connected with the subclaustralis. The outer edge of the clausilium plate rests against the lunella and the subclaustralis in the closed position.
There are two modifications of closing apparatus (Nordsieck 1963: 175, Figs. 2-9). In one type (A, Figs. 5-7) the upper palatal plica is connected with the lunella by an angle or a curve; the lunella is less oblique with respect to the shell axis. In the other type (B, Figs. 2-4, 8-9) the upper palatal plica is connected with the lunella by a curve; the lunella is more oblique with respect to the shell axis. There are two possibilities, how the clausilium plate rests against the subclaustralis; this can be observed by an oblique view into the aperture. In type A (Figs. 6-7) the outer edge of the clausilium plate rests against the subclaustralis up to its distal end and does not overlap this plica, in type B (Figs. 8-9) the outer edge of the clausilium plate overlaps that plica (at least in most specimens) at its distal end. C. i. serravalensis, C. i. rubiginea and outside the southern Alps C. i. punctata (see part 3) exhibit the type A, C. i. albopustulata, C. i. latestriata, C. i. braunii, C. i. baldensis and outside the southern Alps C. i. itala (see part 2) the type B.
Another shell character used for defining subspecies of C. itala is the length of the principal plica. The remaining shell characters, size, shape, sculpture, development of peristome and palatal callus are of minor importance.
Fig. 1. Lunellar of Charpentieria itala (scheme).
lu = lunella; plp = posterior lower palatal plica (subclaustralis); pr = principal plica; pup = (posterior) upper
palatal plica; sc = subcolumellar lamella; sul = lowest palatal plica (sulcalis).
Figs. 2.-5. C. itala.
Actual shell height (mm).
2. C. i. itala, Mira (Villa Ducale) (ex SMF 193974), H = 18.9.
3. C. i. itala, Vicenza (syntype of. C. i. var. vicentina, ex SMF 196209), H = 21.3.
4. C. i. albopustulata, Varone waterfall near Riva (ex SMF 174367), H = 18.3.
5. C. i. serravalensis, Vittorio Veneto (ex SMF 265953), H = 18.4.
Figs. 6-9. C. itala.
Actual shell height (mm) = H.
a. Body whorl dorsal, view on lunellar.
b. Body whorl frontal, oblique view into aperture. Different position of clausilium plate with respect to the
subclaustralis marked by an arrow.
6. C. i. rubiginea, Bozen (ex coll. Bosch), H = 17.1.
7. C. i. punctata, Fivizzano (ex SMF 186744), H = 16.7 (apical part broken).
8. C. i. albopustulata, Lugano (ex coll. Bosch), H = 18.4.
9. C. i. braunii, Heidelberg (castle) (ex coll. Bosch), H = 15.9.
2. C. i. itala:
G. von Martens (1824: 442, pl. 3, fig. 1) described Clausilia itala from Miravecchia („… Garten des aelterlichen Hauses …“, according to E. von Martens 1857: 129 between Mira and Dolo). Zilch (1972: 247) regarded the forms from Monti Berici, Mira and Colli Euganei as representing the nominotypical subspecies and listed the specimens collected by me in Mira (SMF 193974, Nordsieck 2007: pl. 13, fig. 6; Fig. 2) as topotypes. The type form from Mira is relatively small and similar to large forms of C. i. albopustulata (eastern form, see Nordsieck 1963: 177). The samples from Monti Berici (e. g., Arcugnano) and Vicenza (C. i. var. vicentina A. Schmidt 1868, syntypes SMF 196209, Fig. 3) have a larger and more ventricose shell. The samples from Colli Euganei (Abano Terme, Teolo) (C. i. var. vicentina f. tridentina O. Boettger 1879, types SMF 167941) have in part a larger shell, but of the same shape as the type form. In contrast to the other samples, in those from Teolo the clausilium plate does not overlap the subclaustralis (type A).
Among the samples classified by Zilch (: 247) with C. i. itala, however, some from Padova are wrongly affiliated to this subspecies. The sample from Padova (botanical garden) (SMF 156968, including the specimen figured by Zilch 1960: fig. 1532) belongs to C. i. braunii.
C. i. itala does not much differ from C. i. albopustulata (eastern form), but is separated as subspecies because of its shell size (on average larger) and its isolated range (see map). The vicentina form differs from C. i. albopustulata also by its shell shape (more ventricose); thus the type form of C. i. itala is transitional between the vicentina form and C. i. albopustulata. The form from Teolo, however, resembles C. i. serravalensis.
3. C. i. punctata:
The various forms of C. itala from Provence, Maritime and Ligurian Alps and northern and central Apennines (see map) are characterized by a stronger sculpture and a clausilium plate which does not overlap the subclaustralis (type A, Fig. 7). The form from the Provence (Clausilia punctata Michaud 1831) and those from the Apennines (C. alboguttulata var. obesa Issel 1866 [non L. Pfeiffer] from Lucchese, C. a. var. nigra Issel 1866 from Volterra, C. a. var. elegans Gentiluomo 1868 [non Cantraine] from Vallombrosa) do not much differ and are therefore not separated as subspecies (in contrast to Giusti & Mazzini 1971: 295, Zilch 1972: 251).
The whole subspecies has to bear the oldest name C. i. punctata. This was already proposed by Boato et al. (1985: 312), but as cfr. punctata, and Manganelli et al. (1995: 24), but with the statement (: 47): „L‘ attribuzione del materiale della Liguria e dell‘ Appennino a C. i. punctata permane incerta.“
The alleged syntypes of C. punctata from the Rossmässler collection (SMF 196374) are much smaller and more ventricose than the type specimens (Michaud 1831: 55, pl. 15, fig. 23) and belong to C. i. braunii. This has not been noticed by the previous authors (Rossmässler, O. Boettger) and by Zilch (1972: 251), who listed them as syntypes.
It is unclear, if Clausilia genei Lessona 1880 from Valle Pesio, Piedmont, is a form of C. i. punctata, because material is not available.
It should be checked, if C. i. punctata is distributed in Italy beyond the southern border (as indicated in the map), e. g., as far as the Colli Albani, where it is said to occur by E. von Martens (1857: 136).
4. Two misidentified forms of C. itala:
The C. itala form from Meran and surroundings, South Tyrol, differs much from C. i. braunii, as which it was determined in my 1963 paper (: 177). Unlike C. i. braunii it has a long principal plica and a clausilium plate not overlapping the subclaustralis (type A). It thus corresponds with C. i. serravalensis (the only subspecies in which a long principal plica is present, Fig. 7) and is therefore classified with that subspecies. It may have been introduced by man (with winegrowing?) in the region of Meran, like C. i. braunii from Trento into the region of Brixen (see part 1).
The C. itala form from Verona and surroundings, Venetia, differs from C. i. albopustulata, to which it was affiliated in my 1963 paper (: 188), by a more ventricose shell with in part detached aperture. It thus corresponds to C. i. braunii. The forms from the eastern and southern shores of Lake Garda exhibit often a detached aperture, but are more slender than the form from Verona. They are transitional to C. i. albopustulata.
The form from Udine, Friuli, which has been mentioned as Clausilia alboguttulata var. b minor by Pirona (1865 : 692), is strikingly similar to that from Verona, in qualitative shell characters and in the measurements (see Table 1). Nevertheless it has been described by de Mattia et al. (2021) as new subspecies C. i. zalloti. Because of this similarity it is deemed to have been introduced, like other forms of C. i. braunii. Therefore, C. i. zalloti is regarded as a synonym of C. i. braunii.
Table 1. Shell measurements of C. itala (normal subspecies).
Values of extreme or transitional forms in brackets. As a rule 10 specimens per sample have been measured.
|Subspecies (number of samples)||shell height = H (mm)||relative shell width = D/H|
|C. i. albopustulata (11)||16.8-21.2||0.228-0.243 (- 0.253)|
|C. i. latestriata (3)||16.5-16.9||0.237-0.248|
|C. i. braunii (9)
|C. i. itala (4), vicentina form (3)||20.0-22.3, 20.7-21.3||0.231-0.241, 0.254-0.260|
|C. i. punctata (5)||16.4-19.5||0.239-0.243 (-0.260)|
|C. i. rubiginea (6)||16.1-17.3||0.227-0.248|
|C. i. serravalensis (6)||18.9-21.1||0.224-0.246|
In comparison with the other subspecies C. i. braunii and the vicentina form of C. i. itala are characterized by more ventricose shells. The values of the samples from Verona and Udine are nearly identical.
5. C. dyodon:
C. dyodon, which was formerly classified with another group (Dilataria Vest) in another subfamily (Zilch 1960: 401), has been recognized by an examination of the genitalia (Nordsieck 1972: 38) as closely related to C. itala. The shell differs from that of C. itala mainly by the reduction of the sutural papillae and a lunellar tending to reduction. Until now, forms transitional to C. itala have not been found. Therefore, in spite of its genital similarity to C. itala, C. dyodon is regarded as an independent species. Its distributional range in Piedmont (see map) fills partly the gap between that of the C. itala subspecies from the southern Alps and that of C. i. punctata. Therefore I assume that C. dyodon has originated from an isolate of the common stem form in that region. C. itala (with the stenzioid subspecies = C. clavata) and C. dyodon may belong to a monophyletic group of closely related species, the superspecies of C. itala.
For the diversity within C. dyodon see Nordsieck (2002: 36).
6. Subdivision of Charpentieria:
The genus Charpentieria includes besides the superspecies of C. itala two further species, C. ornata (Rossmässler 1836) and C. stenzii. C. ornata differs from C. itala by shell characters somewhat more than the subspecies of the latter from each other (Nordsieck 1963: 198). C. stenzii differs from C. itala in shell morphology, but more in genital morphology (Nordsieck 1963: 191, 201). A subgenus Itala O. Boettger, in which C. itala, C. ornata and C. stenzii are united, has therefore been rejected (Nordsieck 2002: 36).
By DNA analyses (see Appendix) it has been found out that C. dyodon, as assumed in the superspecies concept, is in fact more closely related to C. itala than C. ornata.
Map. Distribution of C. itala subspecies and C. dyodon („stenzioid subspecies“ of C. itala = C. clavata not considered).
Marked ranges cover the regions in which samples of the respective taxa have either been collected or are mentioned in the literature.
Fig. 10. C. i. braunii (type form), on a wall near the castle of Weinheim, Germany.
Appendix: DNA studies on Charpentieria itala
The subspecies division of C. itala (with stenzioid subspecies) from the southern Alps, as proposed in Nordsieck (1963) and once more in this chapter, has been confirmed, at least west of Lake Garda, in the DNA study of Scheel & Hausdorf (2012). The western normal = non-stenzioid subspecies C. i. albopustulata and C. i. latestriata are accepted. In their AFLP network they form four clusters, C. i. latestriata one of them.
The stenzioids (C. i. clavata, C. i. variscoi, C. i. balsamoi, C. i. lorinae), because of introgression from C. itala, are treated as subspecies of C. itala. In the AFLP network the stenzioids form five clusters, because C. i. trepida, which had been included in C. i. lorinae in my 1963 paper, forms a cluster of its own. The transitional forms (C. i. allatollae of the 1963 paper) are assembled in an additional cluster.
The downgrading of the stenzioids to subspecies of C. itala is unsatisfactory, because stenzioids behave in part like species, in part like subspecies (see Nordsieck 1963).
As result of the recently published genome-wide DNA study of Xu & Hausdorf (2020) C. itala revealed as genetically subdivided into two main clades, a western and an eastern one, separated by Lake Garda.
The stenzioids are classified within two species. The western stenzioids, because free of genomic shares with C. itala, are treated as an independent species, while the eastern stenzioids, which exhibit genomic shares with C. itala, are regarded as subspecies of that species (C. i. lorinae, C. i. trepida included). This separation is also unsatisfactory, because the monophyly of the stenzioids is thus obscured. Besides, also in western stenzioids (C. c. clavata) introgression from C. itala has been proved (see Scheel & Hausdorf). The transitional form (C. i. leccoensis of the 1963 paper) is neither considered by Scheel & Hausdorf nor by Xu & Hausdorf.
As concerns the non-stenzioid subspecies in the western clade C. i. albopustulata and C. i. latestriata are accepted as subspecies, the latter, however, only because of its assumed origin by hybridization. The subspecies of the eastern clade are assembled in a subspecies named C. i. itala (because they are not separable in the trees).
This lumping is not in accordance with the shell morphology, especially the development of lunellar and clausilium plate (types A and B), by which the eastern subspecies are well differentiated (see part 1). Besides, C. i. serravalensis exhibits a long principal plica, by which it differs from the other subspecies. According to the authors the subspecies differ morphologically hardly from one another, which means that these morphological differences have not been considered. In the tree of all C. i. populations examined (fig. 5) the eastern subspecies are separable, if the samples are correctly determined. C. itala from the region of Verona had been determined by me (Nordsieck 1963) as C. i. albopustulata, now (see part 4) classified as C. i. braunii, not as C. i. rubiginea, C. itala from Schio as C. i. serravalensis, not as C. i. rubiginea. C. itala from Eisack valley (Atzwang) could be a form of C. i. braunii like the neighbouring one of Klausen-Waidbruck. A good example that the subspecies can be distinguished is the correction of the determination of C. itala from Meran (see part 4), which has been confirmed by the study of Xu & Hausdorf.
It is interesting that in the tree fig. 5 along the branch of itala-E (concluded from figs. 2A and B) admixture from C. i. albopustulata (of itala-W) decreases across C. i. baldensis to C. i. braunii from Verona, C. i. itala and C. i. serravalensis (Schio). Admixture from typical C. i. serravalensis decreases across C. i. serravalensis (Meran) to C. i. serravalensis (Schio). The similarity of C. i. baldensis, C. i. braunii from Verona and C. i. itala with C. i. albopustulata concerning the closing apparatus (type B) is parallel to the admixture from W to E.
Because of the morphological and genetical differences I think that it is not appropriate to lump these subspecies together.
Scheel & Hausdorf (2012) have stated that C. ornata is the sister group of C. itala (+ stenzioid subspecies) and thus more closely related to C. itala than C. stenzii. C. dyodon, however, was not included in this study.
In the DNA study of Xu & Hausdorf (2020) it is shown that C. dyodon, as assumed in the superspecies concept proposed in part 5, is in fact more closely related to C. itala than C. ornata.
Boato, A., Bodon, M. & Giusti, F. (1985): Molluschi terrestri e d’acqua dolce delle Alpi Liguri. – Lavori della Società Italiana di Biogeografia, (NS) 9 : 237-371.
De Mattia, W., Reier, S. & Haring, E. (2021): Morphological investigation of genital organs and first insights into the phylogeny of the genus Siciliaria Vest, 1867 as a basis for a taxonomic revision (Mollusca, Gastropoda, Clausiliidae). – ZooKeys, 1077: 1-175. https://doi.org/10.3897/zookeys.1077.67071.
Giusti, F. & Mazzini, M. (1971): Notulae Malacologicae XIV. I molluschi delle Alpi Apuane. Elenco delle specie viventi con descrizione di una nuova specie: Vitrinobrachium baccettii n. sp. – Lavori della Società Italiana di Biogeografia, (NS) 1 : 202-335, 9 pls.
Manganelli, G., Bodon, M., Favilli, L. & Giusti, F. (1995): Gastropoda Pulmonata. In: Minelli, A., Ruffo, S. & La Posta, S. (ed.): Checklist delle specie della fauna italiana, 16: 1-60. Bologna.
Martens, E. von (1857): Reisebemerkungen über einige Binnenschnecken Italiens. – Malakozoologische Blätter, 4: 120-155.
Martens, G. von (1824): Reise nach Venedig, 2: VI + 664 pp., 9 pls. Ulm.
Michaud, A.-L.-G. (1831): Complément de l’Histoire des mollusques terrestres et fluviatiles de la France, de J. P. R. Draparnaud. – VI+116+12 pp., pls. 14-16. Verdun.
Nordsieck, H. (1963): Zur Anatomie und Systematik der Clausilien, II. Die Formenbildung des Genus Delima in den Südalpen. – Archiv für Molluskenkunde, 92 (5/6): 169-203.
Nordsieck, H. (1972): Zur Anatomie und Systematik der Clausilien, XI. Neue Formen und taxonomische Revision einiger Gruppen der Alopiinae. – Archiv für Molluskenkunde, 102 (1/3): 1-51, pls. 1-5.
Nordsieck, H. (1979): Zur Anatomie und Systematik der Clausilien, XXI. Das System der Clausilien, II: Die rezenten europäischen Clausilien. – Archiv für Molluskenkunde, 109 (4/6): 249-275.
Nordsieck, H. (2002): Contributions to the knowledge of the Delimini (Gastropoda: Stylommatophora: Clausiliidae). – Mitteilungen der deutschen malakozoologischen Gesellschaft, 67: 27-39.
Nordsieck, H. (2007): Worldwide Door Snails (Clausiliidae), recent and fossil. – 214 pp., 20 pls. Hackenheim (ConchBooks).
Pirona, J. (1865): Prospetto dei molluschi terrestri e fluviatile finora raccolti nel Friuli. – Atti del Reale Istituto veneto di scienze, lettere ed arti, (3) 10: 675-708.
Scheel, B. & Hausdorf, B. (2012): Survival and differentiation of subspecies of the land snail Charpentieria itala in mountain refuges in the Southern Alps. – Molecular Ecology, 21: 3794-3808.
Schmidt, A. (1868): System der europäischen Clausilien und ihrer nächsten Verwandten. – 175 pp., 1 tab. Kassel (Fischer).
Strobel, P. (1851): Notizie malacostatiche sul Trentino. – 114 pp. Pavia.
Xu, J. & Hausdorf, B. (2020): Repeated hybridization increased diversity in the door snail complex Charpentieria itala in the Southern Alps. – Molecular Phylogenetics and Evolution. https://doi.org/10.1016/j.ympev.2020.106982.
Zilch, A. (1959-1960): Gastropoda. Teil 2. Euthyneura. – In: Schindewolf, O. H. (ed.), Handbuch der Paläozoologie, 6 (2): I-XII, 1-834. Berlin-Nikolassee.
Zilch, A. (1972): Die Typen und Typoide des Natur-Museums Senckenberg, 50: Mollusca: Clausiliidae (2): Alopiinae: Delimini (1) . – Archiv für Molluskenkunde, 102 (4/6): 247-259, pl. 11.