Strigillaria group – genus and species taxa

Hartmut Nordsieck (IV.2022)

I. Introduction

The Strigillaria group, formerly named Bulgarica, is one of the most diverse groups of the Baleini, Clausiliinae. In a former revision (Nordsieck 1973) the genus Bulgarica was subdivided into four subgenera, B. (Strigilecula), B. (Pavlovicia), B. (Bulgarica) and B. (Denticularia). B. (Pavlovicia), however, has revealed to be more closely related to Vestia. Based on genital morphology and DNA analysis Strigillaria and Bulgarica (with Denticularia) are now regarded as genera of their own (see art. on DNA studies).
The genera include species with distributional ranges of very different extension.
Strigillaria contains two species, S. cana and S. vetusta, which are widespread in eastern or southeastern Europe, respectively. Two further species with small ranges occur in Serbia.
Bulgarica contains several species of different rank, which nearly all are distributed in the eastern part of southeastern Europe from Romania to the Aegean Islands and coastal Anatolia. Two species, B. varnensis and B. thessalonica, are widespread; both are the major species of species groups, including closely related species with smaller ranges. Two pairs of closely related species of B. (Bulgarica), B. rugicollis – B. pagana and B. bulgariensis – B. osmanica, are especially interesting, because on the one hand they occur syntopically without transitions and on the other are connected by intermediate forms.
Several species of Bulgarica have already been revised in more or less detail, together with the description of some new taxa (Nordsieck 1973, supplement 1974).
Since then,  some new subspecies or species have been described (Irikov 2006, Nordsieck 2015). Most recently, I presented partial revisions of some species of both genera, together with the description of new subspecies (Nordsieck 2019).

II. Characters

The characters used for diagnoses of species taxa within the Strigillaria group are listed as follows (with character states; apertural characters see Fig. 1):
Sculpture: whorls ribbed (with different rib densities) or lower whorls only rib-striated (more or less smooth). If ribbing is dense, groups of white more distinct ribs alternate with non-white less distinct ribs = whorls streaked.
Cervix: cervical elevation prominent (= dorsal keel) or weak; cervical bulge before peristome present or absent.
Peristome: outer peristome without or with folds. Folds inwards from outer peristome are named anteperistome folds. In some species also inner peristome (interlamellar, subinterlamellar) with folds.
Inferior lamella: ending in front with two peristome folds = folds of inferior lamella or not.
Subcolumellar lamella: elongated along basal furrow or not. The elongation is caused by connection with a peristome fold.
Anterior lower palatal plica = basalis: present or absent; if present, connected with or separated from lunella.
Anterior upper palatal plica: present or absent; if present, connected with or separated from upper palatal plica.
Clausilium plate:outer (palatal) edge distally more or less raised, forming a terminal outer lobe or not.

Fig. 1. Characters of CA, example Bulgarica t. thessalonica, GR, Euboea, Moni Agia Anna, holotype of var. euboica, SMF 132732.
Body whorl dorsal, frontal and oblique view into aperture, to show lamellae and clausilium plate. Shell height 15.7 mm.
Abbreviations: aupp = anterior upper palatal plica, bas = anterior lower palatal plica = basalis, cp = clausilium plate, il = inferior lamella, lu = lunella, pr = principal plica, sc = subcolumellar lamella, sl = superior lamella, sp = spiral lamella, upp = (posterior) upper palatal plica.
Peristome folds comprise I = interlamellar folds, II = folds of inferior lamella, III = subinterlamellar and basal folds, one elongating subcolumellar lamella, IV = folds of outer peristome.

III. Diagnoses of species taxa

The given values of rib density (R₁) are means of samples (numbers = n).

Strigillaria Vest 1867
(Striolaria Bielz 1867 [nomen oblitum], Strigilecula Kennard & Woodward 1923)

Remarks: Two species belonging to, S. cana and S. vetusta, are widespread European clausiliid species, the intraspecific diversity of  which had not been thoroughly examined until now. Most recently, a partial revision of S. vetusta has been published (Nordsieck 2019).
In contrast to S. vetusta, S. cana has revealed as relatively uniform. This may be caused by the different habitat preferences of both species. S. cana is tree-dwelling (living only in higher altitudes also under stones), inhabiting a large distributional range with similar populations. S. vetusta exhibits a broader ecological spectrum living on rocks and trees. Beside the major subspecies there are numerous intraspecific forms; the most different ones, which may have originated on isolated rock localities, are separated as (minor) subspecies.

S. cana (Held 1836)

Folds of inferior lamella mostly absent; basalis connected with lunella; anterior upper palatal plica absent (indistinct in S. c. transylvanica); clausilium plate without terminal lobe.
Central and eastern Europe from N. Switzerland and W. Germany (highlands, coast of Baltic Sea) to S. Sweden, S. Finland, N. W., central and S. Russia (to Kazan) and N. Ukraine, N. Alps of Austria, Hungary, Carpathian countries to S. W. Romania (southwest to Jiu valley).
c. cana, c. farta (Bielz 1858), c. iostoma (Bielz 1856), c. transylvanica ( Schmidt 1853).
Remarks: An examination of 23 samples of S. cana from the whole distributional range had the following result:
The ribbing of the major subspecies, which occupies nearly the whole range, is remarkably constant (R₁ 4.3-5.3); only in the Carpathians of Romania it is more dense (form praepinguis Charpentier 1852, R₁ 5.2-5.7).  A remarkable form from Prăpăstii, Piatra Craiului Mountains, is more coarsely ribbed (only few specimens available, R₁ <4).
In the southern Carpathians some intraspecific forms occur (Bielz 1867: 162), which differ only slightly from the major subspecies: S. c. transylvanica (= farta var. major, A. Schmidt 1868: 135) in the lower part of Piatra Craiului Mountains, S. c. farta ( = farta var. minor) in the higher parts of Bucegi and Piatra Craiului Mountains, and S. c. iostoma in the Făgăraş Mountains. All three subspecies are more densely ribbed (R₁ 6.4-10.7) than the Carpathian form of the major subspecies. Besides, S. c. transylvanica has weakly ribbed lower whorls and (unique in S. cana) an indistinct anterior upper palatal plica. S. c. farta has a smaller shell with adnate peristome and reduced basalis. It is restricted here to the form from the high Bucegi Mountains, because the similar form from the high Piatra Craiului Mountains has characters in common with S. c. transylvanica (in part anterior upper palatal plica present) and is therefore classified with that subspecies.

S. vetusta (Rossmässler 1836)

Folds of inferior lamella in part present; basalis separated from lunella; anterior upper palatal plica in part present; clausilium plate in part with terminal lobe.
Central Europe (Franconia, Thuringia, Saxony, Bohemia), S. E. Alps (from S. E. Carinthia and adjacent Styria) and Dinaric countries to N. Albania and North Macedonia, Hungary, W. and S. W. Romania, Serbia, W. Bulgaria.
v. conjuncta (Küster 1860), v. kajabaschica (Brancsik 1888), v. nitidosa (Uličný 1893), v. bielzii H. Nordsieck 2019, v. pancici (L. Pfeiffer 1856), v. vetusta.
Remarks: Clausilia vetusta var. minor Rossmässler 1842 [non Rossmässler 1835] from Banat and Tharand (Saxony) is identical with C. v. var. ß syn. striolata Charpentier 1852 [non M. Gallenstein 1848, made available by L. Pfeiffer 1866].The subdivision of A. Schmidt (1868: 136-137), C. vetusta with type form and a variety striolata, was followed by many authors until recently (see Ehrmann 1933, Ložek 1964); besides, Ehrmann (: 76) separated the form from Germany as subsp.v. festiva (Küster 1856). The fact, however, that according to Schmidt (: 136) both, type form and variety, occur in Carinthia in close neighbourhood, did not speak for subspecific rank of var. striolata sensu Schmidt. Also the fact that within var. minor samples from Tharand (festiva) and Banat (striolata) were united, showed that there were no considerable differences between these forms. Therefore, in Nordsieck (2007:63) neither striolata nor festiva were listed as subspecies of S. vetusta.
An examination of 62 samples of S. vetusta from the whole distributional range had the following result:
The intraspecific forms of the species differ mainly in four characters:
shell size,
sculpture (ribbing of lower whorls),
development of anterior upper palatal plica, and
formation of clausilium plate.
Until now, it was not known that a part of the S. vetusta populations exhibit an anterior upper palatal plica, which runs from the palatal callus (hump) to the upper palatal plica. In one and the same population it is present or absent, if present, complete or incomplete ending between the hump and the plica, and distinct or indistinct. The frequencies of its presence, however, are different among the populations.The clausilium plate is narrowed and thickened at the tip, with the outer edge more or less raised forming a terminal lobe or not.
The main stock of the species consists of populations which differ only slightly in these characters. The ribbing of the samples from central Europe, southeastern Alps and northern Dinaric countries (from Carinthia and adjacent Styria to Croatia) is coarser (R₁ 4.8-6.4), that from central and southern Dinaric countries (from Bosnia southwards, with Banat and W. Bulgaria) more dense (R₁ 5.7-8.6). The anterior upper palatal plica is more often present in the samples from western and northern parts of Serbia and adjacent Wallachia,. The clausilium plate of most samples from central and southern Dinaric countries has an on average more pronounced terminal lobe. Provisionally, that main stock is regarded as the nominotypical subspecies. It also includes forms from southern Dinaric countries, which differ somewhat in size and sculpture, Clausilia v. var. striolata f. intermissa and f. laticosta Brancsik 1888, C. v. tenuicula A. J. Wagner 1912, and C. v. nannodes A. J. Wagner 1912 from Bosnia and Herzegovina, and Laciniaria v. gracilior S. H. Jaeckel 1954 from Kosovo.
Within the range of that major subspecies different local forms occur, sometimes in close neighbourhood, e. g. in Banat. One form from there (striolata sensu auct., Cerna valley) is more densely ribbed (R₁ 8.0), another form (Steierdorf), which was misidentified as S. cana by O. Boettger on labels, more coarsely (R₁ 5.9). The following forms with more obsolete ribbing (R₁ > 8.5) are treated as (minor) subspecies:  S. v. nitidosa in Bohemia (regarded as independent species by Ložek 1964), S. v. kajabaschica near Travnik, Bosnia, and S. v. pancici in Beljanica Mountains, Serbia. These rock-dwelling forms with small ranges may have originated from isolates of the major subspecies.
Clausilia conjuncta  Küster 1860 from Majdanpek, Serbia, is a taxon of special interest. This is the form, which L. Pfeiffer (1856:180) received from Zelebor as C. pagana var. latecostata from „Medvenik“, together with C. varnensis sensu Zelebor = C. vetusta. Its shell is more light-coloured and coarsely ribbed than that of the latter. A. Schmidt (1868: 137), who also got it from Zelebor together with C. vetusta, regarded it therefore as separate species. Pavlović (1912: 88) determined it as C. pagana; he gave (: 107) also C. vetusta from some localities near Majdanpek. I collected it in Majdanpek (N 4988, R₁ 4.6) together with a specimen of S. v. vetusta (Nordsieck 2019). The question arises, if it is genetically isolated from S. vetusta and in fact a species of its own. The name conjuncta has been used by all following authors (including Pavlović: 107) for different other distinctly ribbed forms of S. v. vetusta.
In W. Transilvania S. vetusta exhibits a striking diversity. Bielz (1867: 164) subdivided the species from that region into three varieties, C. vetusta var. a = type form, var. b (with distinct ribbing, identified with conjuncta), and var. c (with obsolete ribbing, identified with striolata). The two latter, however, do not correspond to the forms described with these names. C. conjuncta is a special form from Serbia (see above). C. v. var. striolata sensu Schmidt has a normal ribbing. According to my investigation (Nordsieck 2019), two forms of the region, one of them var. b of Bielz, have a coarse ribbing; they are clearly different from the form with dense or obsolete ribbing (var. c of Bielz), which has been described by me as S. v. bielzi.

S. stolii (L. Pfeiffer 1859)

Small, aperture protruding; dorsal keel; inferior lamella without folds in front; subcolumellar lamella in part elongated along basal furrow; basalis and anterior upper palatal plica, if present, separated from lunella or upper palatal plica, respectively; terminal lobe of clausilium plate in part distinct.
E. Serbia (Stol, Rgotina).
Remarks: The formerly used name Clausilia stolensis Moellendorff 1873 is an invalid emendation of C. stolii L. Pfeiffer 1859.
The species is intermediate between S. vetusta and S. serbica. It differs from S. vetusta by the protruding aperture and stronger cervical elevation, characters in common with S. serbica, and subcolumellar lamella less tending to elongation.
Within both examined samples of S. stolii I found few specimens which are transitional to S. vetusta, maybe hybrids.

S. serbica (Moellendorff 1873)

Aperture protruding; dorsal keel; inferior lamella more spirally ascending, mostly without folds in front; basalis mostly connected with lunella; anterior upper palatal plica separated from upper palatal plica; terminal lobe of clausilium plate ± distinct.
E. Serbia (Zlot, Rtanj, Aleksinac).
s. banjana (H. Nordsieck 1973), s. serbica.
Remarks: The replacement of Clausilia serbica Moellendorff 1873 [non Moellendorff 1873] by Bulgarica moellendorffi H. Nordsieck 1972 was nomenclaturally not correct (taxon with replaced name of higher rank than other one, see Welter-Schultes 2012).
Because of its male copulatory organs (with long penial ligaments) S. serbica is clearly a Strigillaria species. It is similar to S. vetusta, but free oviduct and bursa + pedunculus are shorter.
The shell looks like that of some Bulgarica species, but differs from them by the protruding aperture and more spirally ascending inferior lamella. The nominotypical subspecies exhibits a coarse ribbing (R₁ (n = 3) 4.4-5.1); in one and the same population, however, the sculpture can be very different (Nordsieck 1973: 198).

Bulgarica O. Boettger 1877

B. (Bulgarica)
(Idylopsina Lindholm 1924)

B. rugicollis (Rossmässler 1836)
B. pagana (Rossmässler 1842)
(Figs. 2-4)

Dorsal keel; inferior lamella with indistinct or without folds in front; basalis and anterior upper palatal plica distinct to absent, separated from lunella or upper palatal plica, respectively; terminal lobe of clausilium plate mostly weak.
W. Romania (from Şurean and Vâlcan Mountains to Banat and Danube valley), adjacent northernmost Serbia.
B. rugicollis: r. bella (Rossmässler 1842), r. carissima (Rossmässler 1839), r. grossui H. Nordsieck 1973, r. oleata (Rossmässler 1842), r. rugicollis.
B. pagana.
Remarks: According to my examinations B. rugicollis and B.  pagana differ in the male copulatory organs. B. pagana has a shorter parepiphallus and a longer penis which is proximally more slender. Because of their syntopies and the genital differences both are treated as different species (in contrast to Nordsieck 1973, 2007).
Both species have nearly the same range.
Clausilia hasta Küster 1854 and C. ochracea Küster 1854 are probably synonyms of B. r. rugicollis. C. banatica L. Pfeiffer 1848 (made available by Küster 1853) is a large B. r. carissima. C. oleata  (= C. splendens Charpentier 1852) and C. carissima var. bella are separated from B. r. carissima as subspecies of its own (in contrast to Nordsieck 1973, see below). C. obvoluta Küster 1855 is an unknown taxon looking like B. r. bella.
C. pagana mendax A. Schmidt 1868 is a synonym of B. pagana.
B. r. rugicollis (shell densely ribbed: R₁ (n = 7) 11.3-16.5) and B. pagana (shell coarsely ribbed: R₁ (n = 7) 5.3-7.1) (Figs. 2-3) occur sympatrically, in some localities (e. g., Băile Herculane, Mehadia) in close neighbourhood or even syntopically without transitions (emphasized also by Grossu 1981: 233), but are connected by forms with intermediary rib densities, from the same region or another one (Fig. 4), e. g. B. r. grossui (R₁ (n = 6) 6.9-8.2) in an adjacent region of Wallachia and Transylvania.
Two subspecies of B. rugicollis are characterized by their small yellowish-brown shell with nearly smooth lower whorls, B. r. carissima and B. r. oleata. As far as known, B. r. carissima, which exhibits a prominent dorsal keel, is restricted to Mount Domogled near Băile Herculane. B . r. oleata differs by its less prominent dorsal keel; it is known from  the Cerna and Mehadica valleys. Both subspecies occur within the range of B. r. rugicollis, as far as known, without transitions (except C. banatica, a form of B. r. carissima which in shell size is transitional to B. r. rugicollis).
Another small subspecies of B. rugicollis, B. r. bella, differs from both other small subspecies by its ribbed lower whorls. The type form of unknown locality lacks a distinct terminal lobe of clausilium plate, like the other small subspecies. At the southern boundary of the species range, in the Serbian part of the Danube valley (Veliki Djerdap), I collected a small B. rugicollis form similar to B. r. bella. It differs from it, however, by the more pronounced terminal lobe of clausilium plate.
B. pagana occurs also in northernmost Serbia (surroundings of Golubac).
Both Serbian forms of B. rugicollis and B. pagana were unknown to Pavlović (1912). His C. pagana  is S. vetusta conjuncta (see under S. vetusta); as  C. rugicollis from Serbia he mentioned only S. stolii.

B. bulgariensis (L. Pfeiffer 1848)
B. osmanica (Westerlund 1884)
(Figs. 5-7)

Like B. rugicollis, but basalis and anterior upper palatal plica in part connected with lunella or upper palatal plica, respectively; terminal lobe of clausilium plate ± distinct.
Bulgaria (Loveč, region of Veliko Târnovo, Târgovište), S. Bulgaria (Dobrostan).
B. bulgariensis: b. bulgariensis, b. intricata (Mousson 1859).
B. osmanica: o. osmanica (Westerlund 1884), o. pseudofraudigera H. Nordsieck 1973.
Remarks: According to my examinations B. bulgariensis and B. osmanica differ in the male copulatory organs. B. osmanica has a shorter vagina, a more slender pseudoepiphallus and a longer and more slender penis. Both differ from the B. rugicollis – B. pagana species pair by a longer parepiphallus. Because of their syntopies and the genital differences both are treated as different species (in contrast to Nordsieck 1973, 2007).
B. osmanica occurs only in the region of Veliko Târnovo, while B. bulgariensis has a larger range (occurring also in W. and S. Bulgaria).
The species formerly named B. intricata has to bear the oldest name B. bulgariensis, because this name was given by L. Pfeiffer as a synonym made available by A. Schmidt 1868. Clausilia bulgarica Küster 1855 is a synonym of B. b. bulgariensis.
The larger C. rugicollis var. sensu Rossmässler 1842 belongs to B. osmanica.
B. b. bulgariensis (shell coarsely ribbed: R₁ (n = 10) 5.0-9.9) and B. o. osmanica (shell densely ribbed: R₁ (n = 4) 12.2-21.0) (Figs. 5-6) occur sympatrically, in some localities (e. g., Samovodene near Veliko Târnovo) even syntopically without transitions, while in the same region populations with intermediary rib densities (e. g., osmanica from Manastir Sveti Nikola) have been found. Another subspecies with intermediary rib density (R₁ 9.0), B. b. intricata (Fig. 7), occurs in Loveč, N. W. Bulgaria. It differs from the nominotypical subspecies by its longer vagina.
B. o. pseudofraudigera from Drjanovo near Veliko Târnovo is intermediate between B. o. osmanica and B. varnensis; it has possibly originated by interspecies hybridization. In contrast to Nordsieck (1973: 199) it is treated as subspecies of B. osmanica, because in Drjanovo also B. varnensis occurs. B. o. pseudofraudigera replaces there B. o. osmanica (but is less densely ribbed: R₁ 11.2) and occurs syntopically with B. b. bulgariensis.

Figs. 2-7. Bulgarica species pairs.
Frontal and body whorl dorsal. Shell height = H (mm).
2-4. B. rugicollis – B. pagana.
2. B. pagana, RO, Banat, Băile Herculane (left bank of Cerna river), ex SMF 132815; H 14.35.
3. B. r. rugicollis, RO, Banat, Băile Herculane (right bank of Cerna river), ex SMF 132742; H 17.8.
4. B. r. rugicollis x B. r. grossui, RO, S. W. Transylvania, Ponor Ohaba near Pui, ex SMF 320693; H 14.55.
5-7. B. bulgariensis – B. osmanica.
5. B. b. bulgariensis, BG, N. E. Bulgaria, Samovodene near Veliko Târnovo, ex SMF 312914; H 11.3.
6. B. o. osmanica, BG, N. E. Bulgaria, Samovodene near Veliko Târnovo, ex SMF 312915; H 14.4.
7. B. b. intricata, BG, N. W. Bulgaria, Loveč 2 km towards Trojan, ex SMF 312907; H 14.55.

B. varnensis (L. Pfeiffer 1848)

Cervical elevation in part dorsal keel; outer peristome occasionally with indistinct folds; inferior lamella in part with folds in front; basalis connected with lunella; anterior upper palatal plica present to absent, connected with or separated from upper palatal plica; terminal lobe of clausilium plate distinct to absent, mostly weak.
Bulgaria from Godeč and Iskâr valley to Varna, Ruse, S. Bulgaria (Plovdiv), S. E. Romania (Wallachia near Bucureşti, Dobrogea).
v. gabrovnicana Irikov 2006, v. varnensis.
Remarks: Clausilia socialis L. Pfeiffer 1848 is a synonym of B. v. varnensis. Laciniaria cana var. razelmiensis Grossu 1955, L. fraudigera var. montandoni Grossu 1955 and L. dobrogensis Loosjes & Negrea 1968 are forms of B. v. varnensis from Wallachia or Dobrogea, respectively. L. invisa Sajó is a form of  B. v. varnensis from Šipka pass, Bulgaria.
B. v. trimontsiana Irikov 2006 (: 7-8) from Plovdiv is also a form of B. v. varnensis; according to the author it differs by stronger and more strongly sculptured keels of body whorl and the lack of an anterior upper palatal plica, characters which are also found in other forms of the nominotypical subspecies.
In contrast, B. v. gabrovnicana from Gabrovnica valley near Kazanlâk is more different; it is more coarsely ribbed (R₁ 5.2), with more distinct terminal lobe of clausilium plate. It is connected with B. v. varnensis by the form from Šipka, which is more coarsely ribbed (R₁ 6.7) than the other forms of the nominotypical subspecies (R₁ (n = 8) 7.9-10.4).

B. hiltrudae H. Nordsieck 1974

Like B. varnensis, but in part violet brown; lower whorls only rib-striated; dorsal keel; ± with interlamellar folds.
W. Bulgaria (Mezdra).
Remark: B. hiltrudae has probably originated from an isolate of B. varnensis.

 B. fraudigera (Rossmässler 1839)

Like B. varnensis, but dorsal keel; anterior upper palatal plica always present, connected with upper palatal plica.
Bulgaria (valley of Čepelare river).
Remarks: Clausilia rugicollis var. rhodopensis A. J. Wagner in Wohlberedt 1911 is a synonym of B. fraudigera.
B. fraudigera is similar to B. varnensis; both species have the same ribbing. It occurs allopatrically to that species. In Plovdiv, however, both are found in close neighbourhood (see under B. varnensis)..
In genital characters the species is more similar to B. osmanica (free oviduct and pedunculus with bursa long, vagina proximally thicker) than to B. varnensis.

B. urbanskii H. Nordsieck 1973

Like B. varnensis, but shell smaller, on average more coarsely ribbed (R₁ (n = 5) 5.9-7.8); terminal lobe of clausilium plate indistinct.
E. Bulgaria (Sliven, Tvârdica).
u. paganella H. Nordsieck 1974, u. urbanskii.
Remarks: B. urbanskii is similar to B. varnensis, but differs from that species to the same extent as B. fraudigera and B. fritillaria. Its range is inserted in that of B. varnensis (Nordsieck 1974: 158); it is coarsely ribbed like the neighbouring B. v. gabrovnicana and the Šipka form of B. v. varnensis (see under B. varnensis).
In genital characters (vagina and parepiphallus shorter, invagination of penis indistinct) it is more similar to B. fritillaria than to B. varnensis.

B. fritillaria (Frivaldsky 1835)

Like B. varnensis, but shell more ventricose with thick apical part; cervical elevation less prominent; anterior upper palatal plica short to absent; terminal lobe of clausilium plate ± weakened.
Bulgaria (Sliven, Veliko Târnovo, Varna), S. Bulgaria (Petrič, Belovo, Bačkovo).
Remarks: Clausilia cana var. curta A. J. Wagner in Wohlberedt 1911 is a synonym of B. fritillaria.
B. fritillaria is not much different from B. varnensis and B. fraudigera, respectively, but distributed within a greater part of the range of these species, often in close neighbourhood without transitions. It has other ecological preferences than the other B. species (moist habitats) (Urbánski 1969: 241, 1978: 248).
In genital characters it is similar to B. urbanskii (see under that species).

B. hemmenorum H. Nordsieck 2015

Like B. varnensis, but shell more ventricose; anterior upper palatal plica absent (but upper palatal plica in part elongated in front); clausilium plate without terminal lobe.
Greek Macedonia near Kastoria.
Remarks: Until now, B. hemmenorum has thought to be a relative of B. thessalonica (Nordsieck 2015), but the examination of the genitalia revealed it as B. (Bulgarica) species (penis with invagination). The genital characters are similar to those of B. varnensis, but pedunculus with bursa and penis are longer. Its occurrence is far from the range of B. varnensis and the related species from Bulgaria.

 ?B. pindica H. Nordsieck 1974

In comparison with B. hemmenorum more slender, more coarsely ribbed; basalis and anterior upper palatal plica absent.
Thessaly near Kalambaka.
Remark: B. pindica, formerly assumed to be a relative of S. vetusta (Nordsieck 1974), is possibly related to B. hemmenorum and thus a B. (Bulgarica) species. The genital characters, however, are unknown.

B. (Denticularia) Lindholm 1924

Remarks: The material of Bulimus denticulatus Olivier in the Férussac collection (Muséum National d’Histoire naturelle Paris) is mixed from two forms, one from Gemleck = Gemlik, N. W. Anatolia, and one from Scio = Chios Island. Tillier & Mordan (1983: 158) indicated Chios Island as type locality and figured questionable syntypes from the mixed material  (pl. 5, fig. 12, pl. 6, fig. 10), because they were unable to separate the specimens from the two localities. Both forms exhibit a basalis and were therefore classified by me (Nordsieck 2001: 21, 2007) with the species formerly named Bulgarica. thessalonica. The species formerly named B. denticulata got the name of the oldest synonym,  B. erberi. The current revision (Nordsieck 2019), however, has shown that in spite of the presence of the basalis the form from Chios belongs to a subspecies close to B. erberi,  in contrast to the form from Gemlik, which belongs to B. thessalonica. Because Olivier (1801: pl. 17, fig. 9) figured a specimen from Chios Island, that form  is the type form of Bulimus denticulatus, with the result that both species get back their former names, B. denticulata sensu Schütt 2005 and Nordsieck 2007 = B. thessalonica and B. erberi sensu Schütt 2005 and Nordsieck 2007 = B. denticulata.

B. thessalonica (Rossmässler 1839)

Peristome mostly with folds; inferior lamella in part more arch-like than s-like ascending, with folds in front; basalis present (in B. t. mystica reduced), mostly connected with lunella; anterior upper palatal plica mostly present, connected with or separated from upper palatal plica; clausilium plate without terminal lobe.
E. Greece, North Macedonia, S. Bulgaria, Turkish Thrace and N. W. Anatolia within the borderline S. Euboea, Parnassos and Giona Mountains, Efritania, Pindos Mountains, Veles, Blagoevgrad, Plovdiv, Burgas, Bosporus, Bursa, Islands of Thasos and Samothraki, introduced in Italy (Ravenna).
t. boettgeri H. Nordsieck 1993, t. martinae (H. Nordsieck 2019), t. mystica (Westerlund 1893), t. thessalonica.
Remarks: An examination of  35 samples of B. thessalonica from the whole distributional range had the following result:
Clausilia thessalonica Rossmässler 1839 (with var. thasia O. Boettger 1907) from North Macedonia, N. Greece and S. Bulgaria does not much differ in shell characters from C. semidenticulata L. Pfeiffer 1850 (= C. spreta Charpentier 1852 [made available by Küster 1861] = C. thessalonica var. bosporica Mousson 1863) from Turkish Thrace and adjacent N. W. Anatolia. The latter includes the form from Gemlik, N. W. Anatolia, collected by Olivier (Nordsieck 2007: pl. 17, fig. 4). Therefore, both former subspecies (Nordsieck 1973, 2007) are united in the subspecies B. t. thessalonica. C. t. var. euboica O. Boettger 1880 (Fig. 1) is treated as a synonym of B. t. thessalonica.
B. t. var. crassilabris O. Boettger 1880 [non Rossmässler] = B. t. boettgeri (including t. var. tenuilabris Westerlund 1884 [non Rossmässler]), which is characterized by its much thickened peristome with long folds, occurs in Greece in the southernmost part of the species range (Thessaly, Phocis, Efritania).
B. t. mystica from Samothraki Island, formerly regarded as independent species (Nordsieck 1973), is included in B. thessalonica as subspecies. It differs by the absence of peristome folds and the lack of basalis.
B. t. martinae from Lesvos Island (Nordsieck 2019) differs from the nominotypical subspecies by the more slender shell, the coarser ribbing and the reduced outer peristome folds. It is transitional to B. denticulata (see also under that species).
The end genitalia of B. thessalonica introduced in Ravenna, Italy, differ from those from North Macedonia and S. Bulgaria (one sample examined each) by a longer free oviduct and  a shorter vagina. This difference is confirmed by the figures of two forms from S. Bulgaria, given by Urbański (1969: figs. 5-6). According to Schileyko (2000: fig. 945B) the end genitalia of B. denticulata from Selçuk, coastal Anatolia, exhibit also a longer free oviduct and a shorter vagina. The question arises, if B. thessalonica from the Turkish part of its range (semidenticulata) has these characters, too, because the form from Ravenna could have been introduced from there.

B. denticulata (Olivier 1801)

Like B. thessalonica, but shell more slender; anterior upper palatal plica in general absent. In B. d. erberi also basalis absent.
Coastal Anatolia from Izmir to Milas, Aegean Islands (N. Cyclades, Sporades from Chios to Nisiros).
d. denticulata, d. erberi (Frauenfeld 1867).
Remarks: Clausilia mordella Westerlund 1901 is founded on an aberrant shell of B. d. denticulata from Chios. C. denticulata var. spratti O. Boettger 1883 [non L. Pfeiffer] = d. sprattiana K. L. Pfeiffer 1955 and d. var. nicaria O. Boettger 1889 are forms of B. d. erberi from the Sporades.
B. d. denticulata is distributed in W. coastal Anatolia and Chios Island; it is characterized by the presence of a basalis, which is a plesiomorphic character within the species. d. erberi, which lacks the basalis, occurs on the remaining Aegean Islands. In W. coastal Anatolia (Dilek) a transitional form with more or less reduced basalis has been found.
The type form of B. d. erberi from the Cyclades is on average more coarsely ribbed; some samples (e. g., from Tinos Island) exhibit a rudimentary basalis. In the forms from the Sporades a basalis rudiment could not be traced. For the variability of these forms see Pieper (1970).
As can be seen, between B. thessalonica and B. denticulata no sharp dividing line can be drawn.

 B. iniucunda (Brandt 1962)

Dorsal keel; outer peristome with folds; inferior lamella more or less spirally ascending, with folds in front; basalis and anterior upper palatal plica present, connected with lunella or upper palatal plica, respectively; terminal lobe of clausilium plate distinct to indistinct.
E. Greek Macedonia and Thrace from Pangeo and Falakron Mountaina to Rhodopes of Komotini region.
i. iniucunda, i. erossi (H. Nordsieck 2019).
Remarks: In genital characters (vagina, male copulatory organs) B. iniucunda is most similar to B. thessalonica, but parepiphallus and penis are shorter. Therefore, it is classified with B. (Denticularia).
Until now (Nordsieck 2007, 2019), the species was regarded as belonging to B. (Bulgarica), because its clausium plate has a more or less developed terminal lobe. This, however, may be a plesiomorphic character.
B. i. erossi is much different from the nominotypical subspecies; among others, it lacks the anteperistome folds (Nordsieck 2019). This subspecies has been found in Greek Thrace in the easternmost part of the species range.

References

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