Clausilia dubia

Clausilia dubia

Clausilia dubia – a revision based on informative shell characters

Hartmut Nordsieck (III. 2022)

I. Introduction

The subspecies division of C. dubia is difficult, because across the range of the species many forms of different rank are present. The previous revisions of the species (Klemm 1960, Nordsieck 1990, Bank & Gittenberger 2000, Jaksch 2012, Mason et al. 2020) are incomplete, because they are restricted to certain parts of the range. The only complete revision (Nordsieck 2002) is a survey on the different forms of the species with recognition of two major subspecies, d. vindobonensis A. Schmidt 1856 sensu lato and C. d. dubia sensu lato, but without a detailed subdivision into further subspecies.
In the papers of Klemm, Jaksch and Mason et al. a wrong nomenclature is used (see Nordsieck 1990; 145, footnote 16, Bank & Gittenberger 2000: 16-17, 20): C. d. dubia sensu Klemm = C. d. vindobonensis, C. d. obsoleta sensu Klemm = C. d. dubia. It is difficult to understand why this has been continued by Jaksch and Mason et al.
In the same papers from several localities more than one subspecies are given. This is not acceptable.
In Mason et al. no qualitative shell characters are used (though examined according to the authors).
Informative shell characters within the subgenus Clausilia (C.) have been discussed by Neubert & Nordsieck (2002). For this revision those shell characters, which within C. dubia have revealed to be informative were in the focus of attention (see Figs. 1-2):
1. development of inferior lamella;
2. formation of clausilium plate;
3. sculpture.
Shell measurements are no informative shell characters of Clausilia species. Käufel (1929, see also Klemm 1960) united forms of C. dubia with more slender shell, C. rugosa and C. bidentata to one species, without recognizing the differences of the species in the Pyrenees (C. rugosa, C. bidentata, see Nordsieck 1990) or in central Europe (C. dubia, C. bidentata, see Klemm under C. d. moldanubica). Therefore it is not astonishing that also the differentiation of subspecies of C. dubia by shell measurements by Jaksch and Mason et al. failed.
More than fifty intraspecific taxa of C. dubia have been described. In former papers (Nordsieck 1990, 2002) I registered most of these taxa (not considering several taxa, mainly from Westerlund, which refer to infrasubspecific forms of C. dubia from central and northern Europe). Type or original material of the majority of the registered taxa (35) could be studied.
For this revision samples of C. dubia from 115 localities across the whole range have been examined more thoroughly (character states quantified, rib density measured). The rib density is given as rib number per 1 mm of the penultimate whorl = R1.
In the meantime (IV. 2022) the examination has been extended to samples from 160 localities.

Mündung Clausilia d. dubia und d. vindobonensis
Figs. 1-2. Clausilia dubia, characters of CA.
Body whorl partly removed. Shell height = H (mm).
1. C. dubia vindobonensis, A, Lower Austria, Helenental near Baden; H 12.25.
2. C. d. dubia, D, Hesse, Königstein / Taunus; H 12.7.
Abbreviations: cp = clausilium plate; il = inferior lamella; ilp = folds of inferior lamella;  inp = fold of interlamellar; lu = lunella; pr = principal plica; sc = subcolumellar lamella; sl = superior lamella; sp = spiral lamella.
Outer lobe of clausilium plate marked by an arrow.

II. Systematic part

Major subspecies: d. vindobonensis sensu lato, d. dubia sensu lato.

d. vindobonensis sensu lato
Inferior lamella mostly high (more s-like ascending); terminal (outer) lobe of clausilium plate mostly upbent and pointed (see Fig. 1).
Eastern and southeastern part of the range.
1. d. vindobonensis, containing:
a. normal forms
(infrasubspecific: trencsiniensis Brancsik 1888, manina Brancsik 1888, podolica Bakowski 1880, transilvanica A. Schmidt 1856 [non A. Schmidt 1853], moldanubica Klemm 1960):
Densely ribbed (R1 6.6-9.8); inferior lamella and clausilium plate like major subspecies.
Eastern countries, in the west reaching Rügen and Passau, Germany, and in the south Carinthia. traced up to East and South Tyrol (Matrei, Villnöss valley).
Notes: C. d. moldanubica  is a densely ribbed form of d. vindobonensis. Some forms from Lower Austria (e. g., Bad Fischau, R1 11) are transitional to d. huettneri.
b. dwarf forms
(infrasubspecific: runensis Tschapeck 1883, steinbergensis Edlinger 2000):
Small; more densely ribbed (R1 13).
E. Austria.
Note: The runensis form is from Styria (near Rein). The other forms affiliated to C. d. runensis by Klemm (1960) are small forms of C. d. vindobonensis (e. g., the form from Türkensturz, Lower Austria).
2. Weakly sculptured subspecies:
d. gobanzi L. Pfeiffer 1868,  d. speciosa A. Schmidt 1856.
Very densely ribbed or rib-striated (R1 10-14.5); inferior lamella and clausilium plate like d. vindobonensis.
S. E. Carinthia (d. speciosa), E. Styria (d. gobanzi).
Note: C. d. speciosa is restricted to its type locality in Carinthia (Rabenstein ruin). The forms from Lower Austria determined by Klemm (1960) as d. speciosa are C. d. dubia (Traisen valley) or C. d. huettneri or C. d. schlechtii, respectively (Schwarza valley).
3. Coarsely sculptured subspecies:
d. bucculenta Klemm 1960, d. carpathica Brancsik 1888 [non Hazay 1885], d. „costata“ Brancsik 1888 [name not available, because infrasubspecific], d. floningiana Tschapeck 1886, d. grimmeri L. Pfeiffer 1848, dgrimmeri sensu Bielz 1867 = gratiosa Sajó 1968, d. ingenua Hudec & Brabenec 1963, d. otvinensis M. Gallenstein 1895.
Coarsely ribbed (R1 3.2-6.9); inferior lamella and clausilium plate in most subspecies like d. vindobonensis.
E. and S. Austria, Slovakia, Romania.
Note: C. d. floningiana from N. Styria and C. d. „costata” from W. Slovakia exhibit a clausilium plate like d. dubia (subspecies transitional to d. dubia).

d. dubia sensu lato
Inferior lamella mostly moderately high (more steeply ascending); terminal (outer) lobe of clausilium plate not upbent, forming an outer corner (right or obtuse angle) (see Fig. 2).
Western part of the range.
1. Forms transitional to d. vindobonensis
(infrasubspecific: alpicola Clessin 1878, didyma F. J. Schmidt 1847, dydima M. Gallenstein 1852 [non F. J. Schmidt 1847] = ovirensis A. Schmidt 1856, sordellii Adami 1876, langobardica Pini 1883, ? reticulata Pini 1883):
Ribbing like d. dubia; inferior lamella high or moderately high; terminal lobe of clausilium plate like d. dubia, but more frequently somewhat upbent and pointed.
Northern Carpathians, southern Alps (Karawanken to Dolomites, South Tyrol, Lombardy).
Note: Bank & Gittenberger (2000) classify most dubia samples from N. E. Italy with d. dubia, some from the Dolomites between Bozen and Belluno as subspecies of its own d. alpicola. These samples shall be more densely ribbed than d. dubia (R1 11), but the sample from Schlern mountain (type locality), which I examined, exhibits a rib density like other samples from that region (R1 8.5).
2. d. dubia, containing:
a. normal forms
(infrasubspecific: gracilis C. Pfeiffer 1821, roscida Studer 1820 = obsoleta A. Schmidt 1856, fagotiana Bourguignat 1877 = geretica Bourguignat 1877 (name fagotiana chosen by the first revisor, Käufel 1929), suttoni Westerlund 1881 = cravenensis Taylor 1895, pauperata Brancsik 1888).
Densely ribbed (R1 7.6-12.4); inferior lamella and clausilium plate like major subspecies.
Western countries from N. Spain (Catalonia) and England (Pennine mountains) to the boundary against d. vindobonensis in central Europe, northern Carpathians, and eastern and southern Alps.
b. form transitional to the weakly sculptured subspecies
(infrasubspecific: gracilior Clessin 1888 [non Mousson 1863]):
Less densely ribbed than d. huettneri (R1 10-12).
S. E. Lower Austria, N. E. Styria.
3. Weakly sculptured subspecies:
d. huettneri Klemm 1960, d. schlechtii A. Schmidt 1856, d. tettelbachiana Rossmässler 1838.
Very densely ribbed (d. huettneri R1 12-14.5) or indistinctly rib-striated (d. schlechtii, d. tettelbachiana R1 ≥15); inferior lamella mostly high or moderately high; clausilium plate like d. dubia, in one form of d. schlechtii terminal lobe upbent and pointed.
S. Lower Austria and N. Styria.
Notes: The examination of the original sample of C. d. var. tettelbachianae affinis A. Schmidt 1856 = schmidtiana Clessin 1888 had the result that this form from “Styria” is corresponding with d. huettneri. The latter name, however, is not replaced, because the exact locality of C. d. var. schmidtiana is unknown.
C. d. schlechtii has the same sculpture as d. tettelbachiana, but is larger and therefore more slender. It contains two different forms. In the form from the type locality Stixenstein the terminal lobe of clausilium plate is more or less upbent and pointed (form transitional to d. vindobonensis). In the form from the lower part of Höllental (between Hirschwang and Singerin) it is not upbent (like in d. huettneri). A. Schmidt (1856: 36) gave for C. d. var. schlechtii a clausilium plate, which is described as “… flache Rinne, … vorn abgerundet”, i. e., like that of the Höllental form. Therefore, both forms are provisionally not separated as subspecies.
C. d. speciosa sensu Klemm from Höllental and the Rax area belongs to C. d. huettneri or C. d. schlechtii, depending on the sculpture.
The characters of C. d. kaeufeli Klemm 1960 from Hochschwab mountain, N. E. Styria, which according to Klemm shall differentiate it from d. tettelbachiana (shell shape, sculpture, aperture form, formation of clausilium plate) are useless, because they are also found in that subspecies. E. g., the tettelbachiana form from Schauerkogel, Schneealpe (see Pl. 2, Fig. 13), is more distinctly rib-striated (a character differentiating d. kaeufeli) than specimens of other samples of the subspecies. Therefore, kaeufeli is regarded as a synonym of that subspecies This is confirmed by the fact that Klemm could pick kaeufeli specimens out of tettelbachiana samples from Schneealpe, Schneeberg and Rax mountains. On the material from the other localities farther westwards given by Klemm (1960) as kaeufeli cannot be judged, because they could not be examined.

Comment on the material used by Mason et al. 2020:
Material collected in more than 30 localities of Lower Austria has been determined as two dubia subspecies, in some cases even as three.
The sample lists are commented as follows:
d. dubia = d. vindobonensis.
Lists of d. huettneri, d. schlechtii and d. gracilior (= form of d. dubia) each include also the other two named subspecies.
d. kaeufeli = d. tettelbachiana.
d. obsoleta includes d. vindobonensis and gracilior form of d. dubia.
d. runensis = small forms of d. vindobonensis.
d. speciosa = d. schlechtii.
The final remarks of Mason et al. on their subspecies (: 49) are given as follows: „ … C. d. dubia, C. d. moldanubica and C. d. vindobonensis are very similar and their ranges overlap widely. Likewise, the … ranges of the quite similar C. d. kaeufeli and C. d. tettelbachiana overlap to some extent and they occurred frequently at the same locality. Thus, uniting them into one subspecies might be considered.“
These subspecies sensu Mason et al. belong to one and the same subspecies (C. d. vindobonensis or C. d. tettelbachiana, respectively).
„The same is true for C. d. huettneri, C. d. schlechtii and C. d. speciosa …“.
C. d. speciosa sensu Mason et al. belongs to C. d. schlechtii. C. d. huettneri and C. d. schlechtii sensu Mason et al., if collected at the same place, are confused.
I have tried to improve the COI gene tree of Mason et al. (: fig. 3) by correcting the determinations, based on my knowledge of the species from the respective localities. The result was as follows: Now as before, the subspecies are randomly distributed among the clades, and the geographic regions are not revealed. But several (14) subclades with haplotypes of specimens coming from more than one collected sample include only one (or two) subspecies, that is four subclades from the north and east only d. vindobonensis, five from the Schneeberg-Rax region only d. huettneri + d. schlechtii and five from Schneeberg mountain only d. tettelbachiana. This result shows at least a partial separation of these subspecies and besides the close relationship of d. huettneri and d. schlechtii.

The material given as follows is mainly deposited in the collection of the Forschungsinstitut Senckenberg (SMF).

d. vindobonensis

(normal forms):

A, Liechtenstein ruin near Mödling (topotypes vindobonensis, SMF 31899):
R1 mean (7) 9.0.

A, Wien (Dornbacher Park) (SMF 163024):
R1 mean (7) 7.8.

A, Gleißenfeld near Seebenstein (street towards Sollgraben) (SMF 356627):
R1 mean (5) 7.8.

A, Aggstein ruin / Wachau (paratypes moldanubica, SMF 163041):
R1 mean (12) 9.8.

A, Hangender Stein near Bad Fischau (SMF 86547):
R1:mean (10) 10.95.

A, Hermannshöhle near Kirchberg am Wechsel (SMF 356613):
Clausilium plate in part not upbent.
R1 mean (8) 10.25

A, Gösting ruin near Graz (SMF 31940):
R1 mean (9) 8.0.

A, Glanegg ruin near St. Veit (SMF 130331):
Clausilium plate in part not upbent.
R1 mean (12) 7.4.

A, Weiße Wand near Launsdorf (SMF 31906):
Clausilium plate in part not upbent.
R1 mean (12) 8.9.

A, Prossegg-Klamm near Matrei (SMF 182981):
R1 mean (10) 8.1.

I, lower Villnöss valley near Klausen (SMF 130164):
Clausilium plate in part not upbent.
R1 mean (12) 6.8.

D, Passau (Oberhaus) (SMF 264 818):
R1 mean (12) 8.9.

D, Granitz between Binz and Sellin / Rügen (SMF 129822):
R1 mean (4) 7.5.

RUS, Warnicken = Lesnoje / Samland (SMF 86673):
R1 mean (10) 8.1.

LT, Girstupis gorge near Kaunas (SMF 64734):
R1 mean (12) 7.7.

SK, Trenčianske Teplice (Mount Klecpacs) (trencsiniensis, SMF 31275):
R1 mean (12) 9.65.

SK, Manin gorge near Trenčin (manina, SMF 31276):
R1 mean (9) 9.1.

SK, Igló = Spišská Nová Ves (SMF 130377):
Clausilium plate in part not upbent.
R1 mean (6) 7.7.

SK, Szádellö = Zadiel gorge near Turňa (SMF 87189):
Ribbing weakened.
R1 mean (4) 9.1.

PL, Panieńskie Skały near Krakau = Kraków (SMF 130313):
R1 mean (12) 7.9.

UA, Czastowska skala near Lemberg = Lviv (podolica, SMF 199966):
R1 mean (10) 6.8.

HU, Budapest, Fehetefaj (SMF 264754):
R1 mean (8) 7.0.

RO, Hunedoara (Castel) (transilvanica, SMF 323455):
R1 mean (10) 7.2.

RO, Poiana Galdei near Teiuş (towards Întregalde) (SMF 323469):
R1 mean (10) 7.1.

RO, Cheile Runcului near Ocoliş (SMF 327352):
R1 mean (10) 6.9.

RO, Valea Rudăreasa near Ciungetu 6 km above branch towards mountain (SMF 353664):
R1 mean (10) 9.55.

RO, between Moroeni and Zănoaga / Bucegi mountains, 7.1 km from Moroeni (SMF 353615):
R1 mean (10) 6.6.

RO, Valea Şipoaia / Piatra Mare mountains (upper part, ca. 1300 m a. s. l.) (SMF 324514):
Clausilium plate in part not upbent.
R1 mean (8) 7.5.

BIH, Trebesin near Sarajevo (1500-1600 m a. s. l.) (SMF 199987):
R1 mean (8) 9.4.

RKS, Straža near Kačanik (on street Tetovo-Doganović) (coll. Nordsieck 5516):
R1 mean (4) 9.5.

MK, Ljuboten / Šar mountains (1850-2000 m a. s. l.) (SMF 31284):
R1: 11.

(dwarf forms):

A, Steinberg near Grillenberg-Steinhof (paratypes steinbergensis, SMF 323346):
R1: 12, 14.
(SMF 356658):
Clausilium plate in part not upbent.
R1 mean (10) 13.15.

A, Matterleitner Hoher Stein near Rein (syntypes runensis, SMF 86540):
R1 mean (5) 13.2.

d. speciosa:

A, Rabenstein ruin / Lavant valley (SMF 163026):
Ribbing weakened.
R1 mean (6) 10.3.

d. gobanzi:

A, Badlgraben near Peggau (f. magna, SMF 86574, 163025):
Nearly smooth.
R1 mean (18) 10.3.

A, lower Bärenschütz valley near Mixnitz (SMF 86602):
Like preceding.
R1 mean (8) 14.4.

d. otvinensis:

A, Otwinskogel near Launsdorf (SMF 163033):
R1 mean (7) 5.2.

d. grimmeri:

A, Tollgraben near Graz (SMF 163034):
Transitional to d. vindobonensis.
R1 mean (4) 6.9.

A, Jungfernsprung near Deutsch-Feistritz (SMF 31909):
R1 mean (10) 5.0.

A, right Mur bank near Peggau (SMF 199947):
R1 mean (8) 5.2.

d. floningiana:

A, Floningalpe near Kapfenberg (SMF 264778):
Clausilium plate not upbent.
R1 mean (12) 6.1.

d. bucculenta:

A, Innerschildgraben near Scheiblingkirchen (paratypes bucculenta, SMF 163038):
R1 mean (12) 4.2.

d. carpathica:

SK, Mount Kraszina near Trenčin (SMF 86643):
R1 mean (6) 4.9.

SK, Rajec-Teplice near Trenčin (f. minima, SMF 86592):
R1 mean (6) 6.6.

d. „costata“:

SK, Szulyó = Súl’ovské skály near Žilina (f. costata, SMF 86594):
Clausilium plate not upbent.
R1 mean (10) 5.2.

d. ingenua:

SK, Spišska Kotlina near Drevenik / Spišské Podhradie (SMF 199954):
R1 mean (4) 3.2.

d. grimmeri sensu Bielz = gratiosa:

RO, Cheile Turzii near Turda (paratypes gratiosa, SMF 191281):
R1: 6⅔, 5, 5¼.

RO, Mada near Geoagiu (SMF 323459):
R1 mean (10) 4.9.

RO, Peştera Bolii near Petroşani (SMF 86619):
R1 mean (12) 5.0.

d. dubia

(intermediary forms):

DK, Möens Klint (SMF 264829):
R1: 8¼, 8, 8.

SLO, Alpe Ursula = Uršlja gora near Slovenj Gradec (SMF 31929):
R1 mean (10) 9.2.

SLO, Alpe Saplata = Zaplata / Savinja Alps (didyma, SMF 130589):
R1 mean (8) 10.6.

A, Wildensteiner Graben / Obir mountain (SMF 62582):
R1 mean (7) 9.1.

A, Hochobir / Obir mountain (dydima, SMF 130060):
R1 mean (8) 9.9.

SLO, Suha valley near Höflein = Preddvor (SMF 130057):
R1 mean (10) 10.2.

A, Wurzen pass 4 km above branch of Wurzen street (SMF 312696):
R1 mean (10) 9.55.

SLO, Smrekova draga / Trnovski gozd (SMF 129793):
R1: 7, 8, 12.

I, Raibl = Cave del Predil (SMF 130372):
R1: 11, 8, 8½.

I, Luscharigraben = Lussari near Tarvisio (SMF 31253):
R1 mean (5) 9.0.

I, Timau-Pramosio (~ 1100-1200 m a. s. l.) (SMF 31991):
R1 mean (10) 8.6.

I, Prags valley (SMF 264795):
R1 mean (10) 8.1.

I, Schlern (2565 m a. s. l.) (alpicola, SMF 130163):
R1 mean (5) 8.25.

I, Borno / Valcamonica (syntypes? sordellii, SMF 130240):
R1: 12, 10½, 12.

I, Esino / Lecco (SMF 130247):
R1 mean (10) 10.5.

I, Porto Ceresio / Varese (syntypes? langobardica, SMF 130252):
R1 mean (5) 13.7.

(normal forms):

F (lectotype, coll. Draparnaud, Naturhistorisches Museum Wien, Bank & Gittenberger 2000: fig. 5):
R1 ~ 12.

S, Garpenberg / Dalarna (cemetery) (SMF 323906):
R1 mean (4) 8.6.

D, Xanten (eastern city wall) (SMF 264798):
R1 mean (10) 11.7.

D, Nürburg ruin / Eifel (SMF 264823):
R1 mean (10) 9.4.

D, Königstein ruin / Taunus (SMF 330654):
R1 mean (10) 9.5.

F, Odilienburg = Sainte-Odile / Vosges (SMF 335914):
R1 mean (12) 8.5.

D, Mühlheim / Donau (Wulfbach spring) (SMF 335850):
R1 mean (12) 7.7.

D, Jena (SMF 87278):
R1 mean (10) 8.3.

D, Berchtesgaden (St. Bartholomä, way to Eiskapelle) (SMF 130016):
R1 mean (12) 8.5.

CZ, Spitzstein near Saubsdorf = Supikovice (SMF 130288):
R1 mean (12) 9.3.

PL, Mount Czantor near Ustroń (SMF 87182):
R1 mean (10) 8.9.

SK, Vrátna valley / Fatra mountains (pauperata, SMF 130440):
R1 mean (4) 10.1.

A, upper Traisen valley between Freiland and Gsteinach (SMF 31901):
R1 mean (10) 8.95.

A, Kapfenberg (SMF 87225):
R1 mean (12) 10.3.

A, Hallstatt / Salzkammergut (SMF 86654):
R1 mean (12) 7.6.

CH, Via Mala (obsoleta, SMF 130212):
R1 mean (10) 9.4.

CH, L’Abbaye (towards Les Bioux, 1004 m a. s. l.) (SMF 342559):
R1 mean (12) 10.4.

F, Grande Chartreuse (gallica, dupuyana, coll. Bourguignat):
gallica: R1 mean (10) 10.3, dupuyana: R1 mean (9) 10.1.

F, Barèges / Hautes-Pyrénées (fagotiana, SMF 129798):
R1 mean (5) 10.4.

F, Barèges / Hautes-Pyrénées (gallica, coll. Bourguignat):
R1 mean (17) 11.2.

E, Valle de Arán / Lleida (SMF 317363):
R1 mean (5) 12.4.

UK, England, Cark / Lancashire (suttoni, SMF 86672):
R1 mean (4) 9.9.

UK, England, Malham / Yorkshire (SMF 129726):
R1: 9¼, 9, 8⅓.

d. huettneri:

A, Springlessteig / Hohe Wand (paratypes huettneri, SMF 264850):
Ribbing weakened.
R1 mean (9) 13.0.

A, Gutenstein (SMF 86565):
Like preceding.
R1 mean (9) 14.2.

A, Eng at Schneeberg (SMF 31939):
Like preceding.
R1 mean (13) 12.7.

A, Hinterm Faden near Puchberg am Schneeberg (towards Puchberg) (SMF 356615):
Like preceding.
R1 mean (6) 13.6.

A, Höllental between Schwarzau im Gebirge and Singerin (SMF 31900):
Like preceding.
R1 mean (11) 12.4.

A, Naßwald near Schwarzau im Gebirge (Nägelegraben) (SMF 31941):
Like preceding.
R1 mean (12) 13.0.

A, „Styria“ (types schmidtiana, SMF 130052):
R1 mean (8) 13.0.

(forms transitional to d. dubia):

A, Miesenbach near Puchberg am Schneeberg (street towards Lanzing) (SMF 356626):
R1 mean (10) 10.45.

A, Schottwien / Semmering (gracilior, SMF 163031):
R1 mean (7) 10.4.

A, Klamm ruin near Schottwien (SMF 199944):
R1 mean (8) 11.1.

A, Semmering, between station and kurhaus 0.8 km behind branch towards Breitenstein (SMF 356636):
R1 mean (8) 11.75.

A, Semmering (pass, near to restaurant Erzherzog Johann, 1000 m a. s. l.) (SMF 86554, 130477):
R1 mean (12) 11.3.

d. schlechtii:

A, Stixenstein near Ternitz (Schloßpark) (SMF 163030):
Clausilium plate like d. vindobonensis.
Nearly smooth.
R1 15-20.

A, Stixenstein near Ternitz (towards Puchberg am Schneeberg) (SMF 356614):
Like preceding.
R1 mean (10) 16.45.

A, Weichbach valley near Kaiserbrunn (behind entrance) (SMF 356653):
Clausilium plate like d. huettneri.
Nearly smooth.
R1 mean (10) 15.5.

d. tettelbachiana:

A, Schneeberg, between Waxriegel and Kaiserstein (SMF 31934, 163032):
Nearly smooth.
R1: 18-22.

A, Rax, Jakobskogel (SMF 264861):
Like preceding.
R1: 15-19.

A, Rax (summit) (SMF 265663):
Like preceding.
R1: 16-21.

A, Schneealpe (1900 m a. s. l.) (SMF 199982):
Like preceding.
R1: 15-19.

A, Kleinschwab / Hochschwab (2100 m a. s. l.) (types kaeufeli, SMF 163042, 163043):
Very densely rib-striated.
R1: 13-15, holotype 16.

Appendix: C. dubia in Austria, E. Styria:

In E. Styria C. dubia exhibits a striking diversity (Figs. 1-14); this region on the edge of the East Alps is thus for the species a centre of endemism. In the region six subspecies could be traced, with two additional geographic forms: C. d. vindobonensis (Figs. 1-2, with dwarf = runensis form, Fig. 3), C. d. gobanzi (Figs. 4-6), C. d. grimmeri (Figs. 7-8), C. d. floningiana (Fig. 9), C. d. dubia (Figs. 10-11, with gracilior form, Fig. 12) and C. d. tettelbachiana (Figs. 13-14).
According to the examined material their distributional ranges are as follows:
C. d. vindobonensis is distributed in the mountainous region on both sides of the lower Mur valley. Some samples, e. g. from Straßengel and Wildon ruins near Graz (Fig. 1), are because of their clausilium plate transitional to d. dubia. The runensis form was found on a mountain near Rein.
C. d. gobanzi is distributed mainly on the left side of the lower Mur valley from Mixnitz to Peggau. In contrast to the information given by Klemm in the Bärenschütz valley near Mixnitz only C. d. gobanzi (Fig. 6) could be traced.
C. d. grimmeri has been found in the lower Mur valley on both sides of the Mur, C. d. floningiana in and near to the upper Mur valley from Leoben to Kapfenberg. The grimmeri form from Tollgraben, Graz (Fig. 7), is in sculpture transitional to C. d. vindobonensis. There is also a sample of floningiana collected by A. J. Wagner in Judenburg.
C. d. dubia is distributed in the west, in the east up to the lower Mur valley (Frohnleiten) and the Mürz valley. The forms from Salza and Mürz valleys are in sculpture similar to the gracilior form of C. d. dubia, which has been traced on Semmering pass.
The examined samples of C. d. tettelbachiana (including typical C. d. kaeufeli sensu Klemm) come from higher altitudes of Hochschwab and Schneealpe mountains (1600-2200 m a. s. l.). The forms differ in the strength of their rib-striation (Figs. 13-14).
According to my examination C. d. huettneri and C. d. schlechtii could not been traced in Styria with certainty. C. d. var. schmidtiana from „Styria“ = C. d. huettneri (see Material) has no exact locality. C. d. huettneri sensu Klemm from Styria, as far as examined, refers to C. d. dubia (Mürz valley) or C. d. vindobonensis, respectively (lower Mur valley). C. d. schlechtii sensu Klemm from Styria (Schneealpe) belongs to C. d. tettelbachiana.
In no locality of the region more than one subspecies could be found. Several localities given by Klemm for the different subspecies are according to my examination based on wrong determinations.


Plate 1
Figs. 1-6: Diversity of Clausilia dubia in  A, E. Styria.
Shell frontal, body whorl dorsal and views into aperture; H = shell height (mm).; phot. S. Hof.
Fig. 1: C. dubia vindobonensis, Wildon castle near Graz, ex SMF 130061, H 15.3.
Fig. 2: C. d. vindobonensis, Gösting ruin near Graz, ex SMF 31940, H 10.0.
Fig. 3: C. d. vindobonensis (dwarf form), syntype of runensis, Matterleitner Hoher Stein near Rein, ex SMF 86540, H 7.8.
Fig. 4: C. d. gobanzi, Peggau ruin near Peggau, ex SMF 264763, H 13.5.
Fig. 5: C. d. gobanzi, Badlgraben near Peggau, ex SMF 86574, H 16.45.
Fig. 6: C. d. gobanzi, lower Bärenschütz valley near Mixnitz, ex SMF 86602), H 11.2.
Plate 2
Figs. 7-14. Continued.
Fig. 7: C. d. grimmeri, Tollgraben near Graz, ex SMF 163034, H 10.6.
Fig. 8: C. d. grimmeri, Jungfernsprung near Deutsch-Feistritz, ex SMF 31909, H 10.7.
Fig. 9: C. d. floningiana, Floning mountain near Kapfenberg, ex SMF 264778, H 10.8.
Fig. 10: C. d. dubia, Kapfenberg, ex SMF 87225, H 13.3.
Fig. 11: C. d. dubia, Eppenstein ruin near Judenburg, ex SMF 86578, H 11.4.
Fig. 12: C. d. dubia (gracilior form), Semmering (pass, near restaurant Erzherzog Johann, 1000 m a. s. l.), ex SMF 86554, H 12.9.
Fig. 13: C. d. tettelbachiana, Schneealpe, Schauerkogel (1750-1788 m a. s. l.), ex SMF 31916), H 10.5.
Fig. 14: C. d. tettelbachiana, Hochschwab (1625-2278 m a. s. l.), ex SMF 130459), H 8.45.

III. Fossil record

C. dubia is frequent in Quaternary faunas. Only specimens from Early Pleistocene and early Middle Pleistocene deposits of Lower Austria (and Poland) and central / southern Germany (2.6 – 0.4 Ma ago) have been examined.
Since the first appearance of the species (Early Pleistocene, 2.6 Ma ago) the major subspecies of C. dubia can be traced. The layers of Lower Austria yielded C. d. vindobonensis, those of central / southern Germany C. d. dubia.
The samples are ordered according to age.
Only the SMF numbers are given. The rest of the material (except of the samples from Kielniki 3A and Weißenburg 7) is deposited in the Naturhistorisches Museum Wien.

Early Pleistocene, A, Stranzendorf D, SMF 344014:
R1: 9, 8½.
= cf. d. vindobonensis.

Only from the following samples the clausilium plate of specimens could be examined:

Early Pleistocene, A, Stranzendorf I:
R1: 9.
= d. vindobonensis.

Early Pleistocene, A, Krems-Schießstätte 7/2:
R1 mean (13) 9.9.
Early Pleistocene, PL, Kielniki 3A:
R1 mean 8.4.
Early Pleistocene, A, Radlbrunn, SMF 341500:
R1 mean (12) 8.4.
= d. vindobonensis (transitional to d. dubia).

Early Pleistocene, A, Deutsch-Altenburg 37, SMF 344015:
R1 mean (8) 9.4.
Early Pleistocene, A, Deutsch-Altenburg 4B, SMF 344016:
R1 mean (16) 8.3.
= d. vindobonensis.

Middle Pleistocene, D, Weißenburg 7:
R1: 10, 9, 9.
= d. dubia.

Middle Pleistocene, A, Hundsheim:
R1: 6; 11, 8.
= d. vindobonensis.

Middle Pleistocene, D, Wiesbaden (Mosbach III), SMF 334855:
R1 mean (10) 7.8.
Middle Pleistocene, D, Wiesbaden (Hessler), SMF 258296:
R1 mean (12) 8.35.
= d. dubia.


Bank, R. A. & Gittenberger, E. (2000): On the polytypic and problematic Clausilia dubia: notes on its nomenclature and systematics (Gastropoda, Pulmonata, Clausiliidae). – Basteria, 64: 15-27.

Bielz, E. A. (1867): Fauna der Land- und Süsswasser-Mollusken Siebenbürgens. 2. Aufl. – VIII + 216 pp. Hermannstadt.

Jaksch, K. (2012): Phylogeographie und Unterartklassifikation von Clausilia dubia Draparnaud, 1805 im östlichen Österreich (Gastropoda: Pulmonata: Clausiliidae): 93 pp. Diplomarbeit, Vienna University.

Käufel, F. (1929): Beitrag zur Kenntnis der spanischen Clausiliiden, gesammelt von Dr. F. Haas in den Jahren 1914-1917. – Senckenbergiana, 11: 13-21.

Klemm, W. (1960): Clausilia dubia Draparnaud und ihre Formen in Österreich. – Archiv für Molluskenkunde, 89 (1/3): 81-109, pls. 10, 10a.

Mason, K., Sattmann, H., Eschner, A., Duda, M., Harl, J., Kruckenhauser, L., Leeb, C. & Haring, E. (2020): Variation in mitochondrial sequences and shell morphology of Clausilia dubia Draparnaud, 1805 (Gastropoda: Clausiliidae) in eastern Austria. – Arianta, 8: 38-57.

Nordsieck, H. (1990): Revision der Gattung Clausilia Draparnaud, besonders der Arten in SW-Europa (Das Clausilia rugosa-Problem) (Gastropoda: Stylommatophora: Clausiliidae). – Archiv für Molluskenkunde, 119 (4/6): 133-179, 3 pls.

Nordsieck, H. (2002): The subspecies classification of Clausilia dubia Draparnaud (Gastropoda: Stylommatophora: Clausiliidae), a critical revision. – Mitteilungen der deutschen malakozoologischen Gesellschaft, 68: 37-44.

Nordsieck, H. & Neubert, E. (2002): How to determine clausiliid species, I: Widespread species of Clausilia Draparnaud (Gastropoda: Stylommatophora: Clausiliidae). – Mitteilungen der deutschen malakozoologischen Gesellschaft,  68: 31-36.

Schmidt, A. (1856): Die kritischen Gruppen der europäischen Clausilien. I. – VI + 63 pp., 11 pls. Leipzig.