Delima – a genus with high diversity

Hartmut Nordsieck (X. 2021, supplemented III.2022)

I. Introduction

Delima Hartmann 1842 is a genus of the Delimini (Alopiinae, Clausiliidae), which exhibits a remarkably high diversity. It includes 17 species with more than 60 subspecies. The genus is distributed in the Dinaric countries from easternmost N. Italy (Venezia Giulia) to central Albania, inland to high Croatia, W. Bosnia, Herzegovina, inland Montenegro and N. Albania. For the geological and ecological conditions of the region see Nordsieck (1969b).
A shell-based system of the genus has been proposed by Nordsieck (1969b). In this paper already interspecies hybridization, which is frequent in some groups of the genus, has been discussed (see website article on hybridization). Types and nomenclature of Delima species are treated in Zilch et al. (2002), in which also figures of the species taxa are given.
The high intraspecific variability and the tendency to develop local forms have caused the proposal of many species and a plethora of names for their varieties by conchologists of the 19^th century. Since the first description of Delima species in 1829 (J. A. Wagner) until 1862 more than 50 species have been described, mainly by Rossmässler, L. Pfeiffer, Küster and Charpentier. In the epoch-making revision of A. Schmidt (1868) the species number has been restricted to 30. By further descriptions until 1901 the species number increased again to more than 80, mainly by the works of Küster, O. Boettger and Westerlund.  In contrast, A. J. Wagner (1924, 1925), who was the first to define the (sub) genus Delima by genital morphology and distribution, limited the species number to 18.
In the time space from 1829 to 1925 more than 170 names for species taxa (vars. major and minor not considered) have been published, many of them with insufficient diagnoses and without or with wrong locality data. Therefore, in the sixties of the past century, when I worked out the revision of the genus (see above), it was no easy task to identify and assign these taxa names to the species taxa regarded as valid (about 100 cited in Zilch et al. 2002). The system proposed in this paper (modified as given in part II) has been largely confirmed by genital examination of nearly all species and many subspecies in the last years (see part III). DNA analyses have made possible insights into the phylogeny of the genus (see website article on DNA studies).
Because of its main distribution in coastal regions of the Adriatic Sea, its species are highly endangered by human activities (urbanization of the coast for tourism, especially in Croatia also renovation of old walls and ruins) and the climate change, especially by heat, drought and fire. According to my experience, in the last two decades the population densities of many species have dramatically decreased.

II. Shell diagnoses and distribution

Note: The former subdivision in two subgenera (D. (Delima), D. (Semirugata)) is rejected (see part III). Also in DNA analyses these subgenera are not recognizable. For the subgenus division of Delima proposed in this article see website article on DNA studies (Project 3).

D. (Delima)

= laevissima group

See species diagnosis. In contrast to the other groups without sutural papillae and lamella inserta.

 laevissima (Rossmässler 1833)

Peristome attached; lunellar dorsolaterally to laterally situated; basalis present to absent, if present, separated from lunella, sulcalis weak to absent, mostly separated from lunella.
Dalmatia with adjacent Montenegro.
l. laevissima
l. pachygastris (Rossmässler 1835)

D. (Albanica) O. Boettger 1878

 = montenegrina group

See species diagnosis. In contrast to the other groups upper palatal plica tending to be elongated in front.

 montenegrina (L. Pfeiffer 1848)

Peristome attached; lunellar dorsally to dorsolaterally situated; upper palatal plica in part elongated in front; upper palatal plica and sulcalis in part separated from lunella, basalis present to absent, if present, separated from or connected with lunella.
Montenegro, western N. and central Albania.
m. montenegrina
m. muralis (Küster 1860)
Including m. cusmichii (Walderdorff 1865), transitional to m. montenegrina.
m. spuzensis H. Nordsieck 1969
m. pseudobinodata ( O. Boettger 1907)
The formerly used name D. m. nodulosa (Moellendorff 1899) is preoccupied [non Monterosato]. The name D. m. pseudobinodata  was chosen by me acting as first reviser (Zilch et al. 2002).
m. tarensis H. Nordsieck 2015
m. semilabiata (Walderdorff 1864)

D. (Dalmatica) O. Boettger 1877

blanda group

Lunellar dorsally to laterally situated; basalis, if present, connected with lunella, sulcalis present, connected with lunella.

Notes: For shells and copulatory organs of the main species see Figs. 1-8.
For interspecies hybridization within the group see Nordsieck (1969b: 274-275, 2007: 99-101) and website article on hybridization.

Figs. 1-4. Shells of Delima blanda group species from Dalmatia.
Frontal and body whorl dorsal. Shell height = H (mm).
1. D. blanda conspurcata, HR, Dalmatia, Split, SMF 94753; H 15.6.
2. D. latilabris tenebrosa, HR, Dalmatia, Sinj, SMF 231465; H 16.7.
3. D. p. pachystoma, HR, Dalmatia, Vrlika, lectotype, SMF 176296; H 18.6.
4. D. albocincta rufa, HR, Dalmatia, Drniš, SMF 191484; H 19.8.

Figs. 5-8. Copulatory organs of Delima blanda group species from Dalmatia (schematized, penial papilla visible).
5. D. blanda conspurcata, HR, Dalmatia, Šibenik.
6. D. latilabris tenebrosa, HR, Dalmatia, Sinj.
7. D. p. pachystoma, HR, Dalmatia, Vrlika.
8. D. albocincta rufa, HR, Dalmatia, Drniš.
Abbreviations: at = atrium, dep = distal part of epiphallus, fod = free oviduct, p = penis, pap = penial papilla, pb = pedunculus (of bursa copulatrix), pep = proximal part of epiphallus, rp = penial retractor, v = vagina, vd = vas deferens.

blanda (Rossmässler 1836)

Yellowish brown; cervical sculpture distinct; peristome mostly attached, not thickened; lunellar dorsally to dorsolaterally situated; basalis present to absent; palatal callus, if present, not protruding inwards.
Part of coastal Croatia, N. and central Dalmatia.
b. blanda
Subspecies intermediate between b. conspurcata and D. latilabris.
b. conspurcata (Rossmässler 1836)
In Drniš transitions to D. pachystoma.
Including b. pustulata (O. Boettger 1879) [non A. Schmidt] (with distinct sutural papillae), transitional to D. a. sororia.
b. fulcrata (Rossmässler 1836)
Including b. tichobates (L. Pfeiffer 1868) (small, slender, with short basalis).
b. schmidti H. Nordsieck 1969
Subspecies transitional to D. pachystoma.

pellucida (L. Pfeiffer 1848)

Yellowish brown; ± distinctly rib-striated; peristome detached; lunellar dorsally situated; lunella above and sulcalis tending to reduction, the latter ± separated from lunella; basalis present.
Central Dalmatia: Kozjak with part of Kaštela and S. E. Zagora (Lečevića, Brštanovo).

latilabris (J. A. Wagner 1829)

Yellowish to reddish brown; cervical sculpture weak; peristome attached, in part thickened; lunellar ± dorsolaterally situated; basalis in general absent; palatal callus, if present, not protruding inwards.
Part of coastal Croatia, N. and central Dalmatia, W. Bosnia, N. W. Herzegovina.
l. latilabris
In Gračac transitions to D. b. consentanea.
l. opaca (Charpentier 1852)
l. michahellis (Küster 1850)
l. helenae (Küster 1876)
This former species (Nordsieck 1969b, 2007)  is downgraded to a subspecies of D. latilabris (see part III).
l. tenebrosa (Küster 1862)
Including l. pachychila (Westerlund 1878) (with thickened peristome).
l. angusticollis (Küster 1876)
Subspecies transitional to D. pachystoma.
l. boettgeri H. Nordsieck 1969
l. duarensis H. Nordsieck 1969
Subspecies transitional to D. b. conspurcata.

pachystoma (L. Pfeiffer 1848)

Yellowish to reddish brown; cervical sculpture distinct to weak; peristome mostly detached and ± thickened; lunellar dorsolaterally to laterally situated; basalis in general absent; palatal callus, if present, protruding inwards to an anterior upper palatal plica.
Central Dalmatia.
p. pachystoma
In Vrlika transitions to D. b. conspurcata.
p. satricensis H. Nordsieck 1969
Subspecies transitional to D. latilabris.
p. sucinacia ( O. Boettger 1879)
In Drniš transitions to D. b. conspurcata.
p. nevestensis H. Nordsieck 1969
p. decattaniae (A. Villa & G. Villa 1871)
This subspecies has some shell characters (colour, sutural thread, cervical sculpture) in common with D. albocincta. This concurs with a genital character (short vagina) shared with D. a. albocincta.
p. vicariella H. Nordsieck 1969
Subspecies transitional to D. b. conspurcata.

albocincta (L. Pfeiffer 1841)

Reddish brown with white sutural thread; cervical sculpture weak; peristome attached or detached, not thickened; lunellar dorsolaterally to laterally situated; basalis present to absent; palatal callus, if present, protruding inwards to an anterior upper palatal plica.
N. and central Dalmatia.
a. albocincta
The nominotypical subspecies is much different from the two following subspecies, also in a genital character (short vagina).
a. rufa (Küster 1876)
In Drniš transitions to D. pachystoma.
a. sororia ( A. Schmidt 1868)
Subspecies transitional to D. b. conspurcata.

binotata group

Lunellar dorsally to dorsolaterally situated; basalis, if present, separated from lunella, sulcalis present, connected with lunella.

Note: As genital examination and DNA analyses have shown, the group is not related to the laevissima and montenegrina groups (contrast to Nordsieck 1969b).

 binotata (Rossmässler 1836)
Peristome attached or detached; lunellar dorsally situated, in part more dorsolaterally; upper palatal plica and sulcalis always connected with lunella; basalis mostly present.
Part of coastal Croatia, Dalmatia, part of W. Bosnia, Herzegovina, W. Montenegro.
b. binotata
b. consentanea (A. Schmidt 1868)
b. hercegovinae (Moellendorff 1873)
b. schlotteri Brancsik 1890
b. grahovensis H. Nordsieck 2015
b. satura (Rossmässler 1836)
b. saturella H. Nordsieck 1969
b. gastrolepta (Rossmässler 1836)

pfeifferi (Küster 1850)

In comparison with D. binotata violet-brown, with white sutural thread; cervical impression more distinct; peristome detached; inferior lamella moderately high; lunellar dorsally situated; basalis absent, in part indistinct.
Central Dalmatia: Promina (Tepljuh, Kaldrma), Vrlika.

semirugata group

Lunellar dorsally situated (in part more dorsolaterally); basalis mostly absent (if present, connected with lunella); sulcalis present, mostly separated from lunella, to absent. In contrast to other Delima groups tending to develop a cervical bulge.

Note: The former subgenus D. (Semirugata) is regarded as synonym of D. (Dalmatica) (see above).

bilabiata (J. A. Wagner 1829)

More distinctly rib-striated; peristome mostly attached, in part thickened; sulcalis in general present, mostly separated from lunella.
Part of coastal Croatia, Dalmatia and adjacent Albania.
b. bilabiata
b. tenella (Küster 1861)
b. crassilabris (Rossmässler 1836)
Including weak islet forms b. busincola A. J. Wagner 1925 and b. planchettensis A. J. Wagner 1925.
b. fasceolata (Charpentier 1852)
b. pharensis (Westerlund 1884)
b. alschingeri (Charpentier 1852)
b. biasolettiana (Charpentier 1852)

semirugata (Rossmässler 1836)

More distinctly rib-striated; peristome mostly detached, not thickened; sulcalis weak to absent, if present separated from lunella.
Part of coastal Croatia, N. and central Dalmatia with adjacent Bosnia, Herzegovina.
s. semirugata
In Hvar Island transitions to D. b. fasceolata.
Including weak islet form s. lesinae A. J. Wagner 1925.
Including s. prunilia (A. Schmidt 1868) (large, dark-coloured).
s. vibex (Rossmässler 1839)
Including unnamed form (more densely ribbed) from Knin region.
s. obesa ( L. Pfeiffer 1861)
The name westerlundi Westerlund 1881 is a synonym of D. s. vibex, not of D. s. obesa (as given in Zilch et al. 2002: 212).
s. blaui (Moellendorff 1873)

hiltrudis H. Nordsieck 1969

Less distinctly rib-striated, sutural papillae distinct; peristome attached; sulcalis present, in general connected with lunella.
Central Dalmatia: Šolta Island, northwestern part of Brač Island.

giselae A. J. Wagner 1914

Sculpture and sutural papillae distinct; peristome detached; sulcalis present, ± connected with lunella.
W. Bosnia: Dinara (Kolmut).

vidovichii (L. Pfeiffer 1846)

Less distinctly rib-striated; peristome attached, mostly not thickened; sulcalis present to absent, if present separated from lunella.
Central Dalmatia and adjacent N. Dalmatia and Bosnia.
v. vidovichii
v. robusta (Küster 1847)
v. callifera (Küster 1853)
v. leucostoma (Küster 1850)

D. (Dugiana) Štamol & Slapnik 2002

edmibrani Štamol & Slapnik 2002

Reddish brown with white sutural thread; weakly rib-striated; spiral lamella and principalis forming a siphon in front; inferior lamella spirally ascending; lunellar dorsolaterally situated; upper palatal plica in part elongated in front; basalis present, mostly connected with lunella, sulcalis connected with lunella; anterior upper palatal plica present, separated from upper palatal plica; clausilium plate distally with upbent palatal edge.
Dalmatia: southwestern tip of Dugi Otok Island.

Note: For further data see Štamol & Slapnik (2002).

By DNA analysis (DNA studies, Project 3) it was shown that D. amoena clusters with a group of Siciliaria (Stigmatica), not with Delima (Dalmatica). Therefore, the amoena group (Substricta O. Boettger 1877) is treated here as probably not belonging to Delima.

amoena group

Lunellar dorsally situated (in part more dorsolaterally); basalis, if present, connected with lunella; sulcalis present, like upper palatal plica in part separated from lunella.

 amoena (L. Pfeiffer 1848)

Rib-striated; lunellar ± complete: upper palatal plica and sulcalis in part separated from lunella; parallel lamella indistinct to absent.
Central and S. Dalmatia (only islands).
a. amoena
a. smokvicensis ( J. Wagner 1915)
a. substricta (Charpentier 1852)

subcylindrica (Rossmässler 1836)

Nearly smooth; lunellar ± reduced to three separated parts: upper palatal plica, lunella with basalis, sulcalis; parallel lamella in part present.
Central and S. Dalmatia: coastland from Omiš to Konavli, eastern tip of Hvar Island, Pelješac Peninsula, eastern part of Korčula Island with scoglios, Islands of Olipa, Jakljan, Šipan, Lopud and probably Koločep.

III. Genital characters

The genitalia of the Delima species are insufficiently known. A. J. Wagner (1913: pl. 572; 1925: pls. 1-4) figured the genitalia of five species (D. laevissima, D. montenegrina, D. binotata, D. latilabris, D. bilabiata), but no information on differences between them was given. In Nordsieck (1969a: fig. 8) only the male copulatory organs of D. albocincta in comparison with other Alopiinae species are figured, and one differentiating character of the genitalia was used for the subgenus diagnoses. The genitalia of D. edmibrani were described and figured by Štamol & Slapnik (2002: figs. 8-9).
Therefore, I examined the genitalia of nearly all (16) species (and 33 subspecies) of the genus (including the amoena group, see II), in order to test the shell-based system formerly proposed.
The genital system of Delima (terms see Nordsieck 2007: Appendix 2) is similar to that of other genera of the Delimini. The allospermiduct is well-visible already along the spermoviduct. The diverticulum of bursa copulatrix is longer than bursa + proximal pedunculus (1.4-2.5). The distal pedunculus is longer than or as long as the vagina (0.7-3.6 (-5.2)), i. e., the vagina is more or less shortened. The vaginal retractor is inserting on the distal pedunculus; the pedunculus beyond retractor insertion is thicker. The penis is longer than or as long as the vagina (0.6-3.5 (-4.3)). It is not subdivided into proximal and distal part as in other genera of Delimini. The penial papilla is mostly shorter than half the penis (in D. vidovichii it is absent); the papilla base is distinct (see Nordsieck 1969a). The epiphallus is longer than or as long as the penis (0.8-1.8), without thickening at its distal end; the proximal part is longer than the distal one (1.2-3.3).

Table: Length ratios of end genitalia of selected Delima species.
Abbreviations used: bb+ppb = bursa + proximal part of pedunculus, dpb = distal part of pedunculus, db = diverticulum, dep = distal part of epiphallus, ep = epiphallus, p = penis, pap = penial papilla, pep = proximal part of epiphallus, v = vagina.
Terms proximal and distal defined as seen from the gonad.
In the table  the collection numbers of preparations are given. They are made from samples of collection Nordsieck (N).

12 D. b. binotata, HR, Senj (N 3985);
15 D. m. montenegrina, MNE, Njeguši near Cetinje (N 3804);
164 D. blanda conspurcata, HR, Solin near Split (N 1372);
172 D. vidovichii robusta, HR, Klis near Split (fortress) (N 1388);
174 D. blanda conspurcata, HR, Šibenik (N 1359);
188 D. semirugata vibex, HR, Pirovac near Šibenik (N 3930);
664 D. a. amoena, HR, Polače on Mljet (N 12504);
672 D. laevissima pachygastris, HR, Slano (N 12465);
674 D. vidovichii robusta, HR, Klis near Split (waterfall) (N 11698).

The results of all examinations are as follows:
The length ratios of the end genitalia of the Delima species are not much different.
Except of the laevissima group the subgroups of the genus based on shell morphology cannot be defined by genital characters. In nearly all subgroups there are species more or less diverging from the other species within the group.

D. (Delima)

= laevissima group:

D. laevissima differs from the other species of the genus by the strong sphincter at distal end of pedunculus (at insertion point of a long vaginal retractor) and the much oblique penial papilla base. This concurs with its shell peculiarities.

D. (Albanica)

= montenegrina group:

Compared with the other Delima species, D. montenegrina has a relatively long diverticulum.

D. (Dalmatica):

blanda group:

Within this group in the D. pachystoma–albocincta subgroup the penial papilla base is more distinct and the proximal part of epiphallus in relation to the distal part longer than in D. blanda (except of D. b. schmidti) (Figs. 5-8). In the latter character D. latilabris has an intermediary position. This is in accordance with the shell differences of these species (Figs. 1-4).
In comparison with the other subspecies, D. b. schmidti has a longer diverticulum and a longer proximal part of epiphallus like D. pachystoma. This agrees with its judgement as subspecies transitional between both species.
D. pellucida is most similar to D. blanda, with another penis shape.
D. l. latilabris and D. l. helenae have a relatively long vagina. The latter fits the species D. latilabris, so that its ranking as subspecies of this species (in contrast to Nordsieck 1969b) is supported.
D. a. albocincta differs from D. a. rufa and D. pachystoma by the shorter vagina. This applies also to D. p. decattaniae, a subspecies intermediate between D. pachystoma and D. albocincta.
D. a. sororia is more similar to D. albocincta than to D. blanda, though from shell characters it is judged as subspecies transitional to D. b. conspurcata.

binotata group:

D. pfeifferi differs from the closely related D. binotata by the longer vagina.

semirugata group:

The species of this group have a relatively long vagina (but there are also subspecies with shortened vagina). A longer vagina has also been found in D. amoena and D. pfeifferi as well as in D. (Dugiana). Its length is thus not suited to separate the semirugata group as subgenus D. (Semirugata), as formerly proposed (Nordsieck 1969a).
D. hiltrudis has a shorter diverticulum and a shorter proximal part of epiphallus than the other species of the group.
D. vidovichii differs from the other species of the group and the whole genus by the absence of the penial papilla.

D. (Dugiana):

D. edmibrani differs from the other species of the genus by the long vagina and the short distal part of epiphallus. This concurs with its remarkable shell differences.

amoena group (probably not belonging to Delima, see II):

D. subcylindrica differs from D. amoena by the shorter vagina and the somewhat longer penial papilla (length in relation to penis mean 0.6, amoena 0.5).

References

Nordsieck, H. (1969a): Zur Anatomie und Systematik der Clausilien, VI. Genitalsystem und Systematik der Clausiliidae, besonders der Unterfamilie Alopiinae. – Archiv für Molluskenkunde, 99 (5/6): 247-265.

Nordsieck, H. (1969b): Zur Anatomie und Systematik der Clausilien, VII. Dinarische Clausiliidae, I: Das Genus Delima. – Archiv für Molluskenkunde, 99 (5/6): 267-284.

Nordsieck, H. (2007): Worldwide Door Snails (Clausiliidae), recent and fossil. – 214 pp., 20 pls. Hackenheim (ConchBooks).

Schmidt, A. (1868): System der europäischen Clausilien und ihrer nächsten Verwandten. – 175 pp., 1 tab. Kassel (Fischer).

Štamol, V. & Slapnik, R. (2002): Delima (Dugiana) edmibrani n. subgen. and n. sp. from Croatia (Gastropoda: Pulmonata: Clausiliidae). – Archiv für  Molluskenkunde, 130 (1/2): 239-248.

Wagner, A. J. (1913-1915): Familie Clausiliidae. – In: Rossmässler, Iconographie der Land- und Süßwassermollusken, (2) 21: 1/2 (1913): 1-20, pls. 571-580; 3/4 (1914): 21-44, pls. 581-590; 5/6 (1915): 45-65, pls. 591-600. Wiesbaden (Kreidel).

Wagner, A. J. (1924): Systematisches Verzeichnis der mir heute bkannten Arten und Formen der Clausiliiden. III. – Annales Zoologici Musei Polonici Historiae Naturalis, 3 (3/4): 99-126.

Wagner, A. J. (1925): Studien über die Systematik, Stammesgeschichte und geographische Verbreitung des Genus Delima (Hartmann) A. J. Wagner. – Annales Zoologici Musei Polonici Historiae Naturalis, 4 (1): 1-73, 16 pls.

Zilch, A., Nordsieck, H. & Neubert, E. (2002): Die Typen und Typoide des Natur-Museums Senckenberg, 83: Mollusca: Clausiliidae (7): Alopiinae (5): Delimini (1) . – Archiv für  Molluskenkunde, 130 (1/2): 201-237, 10 pls.