Vertigo (Vertigo) nitidula ( Mousson, 1876 )

Walther, Frank, Kijashko, Pavel V. & Hausdorf, Bernhard, 2014, Redescription of Ve r t i g o (Vertigo) nitidula (Mousson, 1876) (Gastropoda: Vertiginidae) from the Caucasus region, Zootaxa 3872 (1), pp. 75-82 : 75-80

Vertigo (Vertigo) nitidula ( Mousson, 1876)

Pupa ( Vertigo ) pygmaea var. nitidula Mousson, 1876: 143 .

Pupa (Vertigo) sieversi Boettger, 1879: 390 , 407, pl. 10 fig. 6; Boettger 1883: 184. Pupa (Vertigo) sieversi var. punctum Boettger, 1879: 407 , pl. 10 fig. 7; Boettger 1880: 141. Pupa (Vertigo) sieversi var. punctulum [sic]: Boettger 1879: 407. Pupa (Vertigo) substriata var. mitis Boettger, 1880: 140 , pl. 4 fig. 7. Pupa (Vertigo) sieversi var. subalpestris Boettger, 1880: 141 . Vertigo (Alaea) sieversi var. punctum: Boettger 1886a: 309 .

Vertigo sieversi var. punctum: Boettger 1886b: 151 .

Vertigo sieversi var. subalpestris: Boettger 1889: 25 ; Pilsbry 1919: 196. Pupa sieversi : Rosen 1907: 205.

Pupa (Alaea) sieversi: Rosen 1911: 121 .

Vertigo substriata var. mitis: Pilsbry 1919: 173 , pl. 17 fig. 4.

Vertigo sieversi: Pilsbry 1919: 195 , pl. 17 fig. 11–12; Sysoev & Schileyko 2005: 241; Pokryszko et al. 2011: Appendix S2, S3; Sysoev & Schileyko 2009: 51, fig. 20M; Mumladze 2000: 14, 16.

Vertigo sieversi var. punctulum [sic]: Pilsbry 1919: 196, pl. 17 fig. 13.

Vertigo (Vertigo) substriata var. mitis: Likharev & Rammelmeier 1952: 135 .

Vertigo (Vertigo) substriata var. sieversi: Likharev & Rammelmeier 1952: 135 .

Vertigo substriata: Lezhawa 1962: 328 [misidentified]; Lezhawa 1966: 9 [misidentified]; Aliev & Aliev 1972: 34 [misidentified]; Javelidze 1972: 29, fig. 21 [misidentified]; Lezhawa 1973: 24 [misidentified]; Lezhawa 2000: 86 [misidentified]; Sysoev & Schileyko 2005: 241 [partly misidentified]; Sysoev & Schileyko 2009: 51, fig. 20N [partly misidentified].

Vertigo substriata sieversi: Akramowski 1968: 26 ; Akramowski 1971: 6; Asadov et al. 1975: 101; Akramowski 1976: 136, text-fig. 56, 57B, pl. 5 fig. 48.

Vertigo (Vertigo) substriata: Schileyko 1984: 201 , fig. 118-119 [partly misidentified]; Kijashko 2000: 11, 12, 14, 21 [misidentified].

Vertigo (Vertigo) sieversi: Schileyko 1984: 204 , fig. 123; Egorov 2008: 35, pl. 5 fig. 32; Kijashko 2000: 9, 12, 14, 18, 21.

Shell ( Fig. 1 A– O). Shell elongate-ovate or rarely ovate with a rounded apex; perforate; upper whorls irregularly rib-striated; the striation becomes weaker on the body whorl; corneous or greenish-brown; subtranslucent; 4.5 – 5 moderately convex whorls; body whorl slightly ascending towards the aperture, with a shallow impression behind the weak cervical crest above the lower palatal fold; aperture rounded triangular; insertions of peristome connected by a weak callus; peristome slightly expanded, not reflected, only slightly thickened; palatal margin straight with only a shallow indentation; occasionally with a white callus at the inside corresponding to the cervical crest; parietal lamella higher than angular lamella, which is sometimes completely missing; columellar lamella strong; lower palatal fold stronger than upper palatal fold; basal fold more or less strong, missing in some specimens or even whole populations.

Measurements ( Fig. 2 ). 57 specimens from 13 populations (n=1 – 18 per population): shell height: 1.50–2.20 mm, mean 1.85 + 0.18 mm; shell diameter: 0.90–1.15 mm, mean 1.03 + 0.06 mm.

Species delimitation. V. nitidula is similar to V. substriata ( Jeffreys, 1833) ( Fig. 1 P–V), but differs from this species in the finer radial sculpture on the upper whorls, which are ribbed in V. substriata , and the only moderately convex whorls. Moreover, most specimens of V. nitidula are more elongated than specimens of V. substriata .

The shell variability within V. nitidula is high. The varieties Pupa sieversi var. punctum Boettger, 1879 ( Fig. 1 C) and Pupa sieversi var. subalpestris Boettger, 1880 ( Fig. 1 D) were based on differences in shell shape and the development of the angular lamella. However, these as well as other variations of shell characters are not characteristic for specific geographic regions. Shell size and shape vary continuously ( Fig. 2 ). Different shell shapes and the presence or absence of angular lamella and basal fold are found in various combinations and different forms can co-occur within a single population (see Fig. 1 H–J and K – O). Thus, we cannot split this complex into smaller entities and place the named varieties in the synonymy of V. nitidula .

Boettger (1880) described a short Vert igo form from Abastumani and Kazbek as P. substriata var. mitis . He stated that it differs from P. sieversi (= V. nitidula ) in the more strongly sculptured, less turrited shell. However, a re-examination of the syntypes ( Fig. 1 E) has shown that the upper whorls of this form are not ribbed as in V. substriata , but coincide in sculpture with those of V. nitidula . The three available syntypes of P. substriata var. mitis from Abastumani differ from the three specimens from the same locality determined as P. sieversi by Boettger (1880) in the smaller shell height and the reduction of the angular lamella, but not in shell sculpture. Thus, we place P. substriata var. mitis Boettger, 1880 in the synonymy of V. nitidula .

Schileyko (1984) considered the lack of the basal fold as the decisive diagnostic feature for distinguishing V. nitidula from V. substriata . However, the basal fold is present in the syntypes of V. nitidula ( Fig. 1 A) as well as in the syntypes of P. sieversi ( Fig. 1 B). As already noted by Boettger (1880), a basal fold may be missing in some populations of V. nitidula . The same is true for V. substriata . Thus, this character cannot be used to distinguish these species.

Vertigo substriata has been reported repeatedly from the Caucasus region. However, most vouchers determined as V. substriata turned out to belong to V. nitidula . Obviously, they were misidentified as V. substriata because of the unclear delimitation of V. nitidula and V. substriata . Only three samples from the Chegem valley in Russia (ZIN 96/2, Fig. 1 S), from Kobi in Georgia, 42°33'N 44°30'E, (ZIN 95/30, Fig. 1 T – V) and from Arakani in Dagestan, 42°37'N 47°00'E (ZMMU Lc-7656/1), all on the northern slope of the Greater Caucasus, belong to Vertigo substriata . Near Kobi V. nitidula and V. substriata occur in sympatry, but do not show transitions (compare Fig. 1 F – G versus 1T – V). This confirms the classification of V. nitidula as a separate species.

We re-examined samples of V. substriata from the Ural ( Fig. 1 Q; voucher to Horsák et al. 2010), Altai mountains ( Fig. 1 R; voucher to Pokryszko & Horsák 2007) and the Crimean Nature Reserve (IZK; partly vouchers to Balashov & Baidashnikov 2012) and confirmed their specific identity with Central and Western European specimens ( Fig. 1 P). Consequently, V. nitidula can be ranked as a Caucasian endemic, while V. substriata ranges from Western Europe to the Ural and the north side of the Great Caucasus with isolated occurrences in the Altai.

Nomenclature. Mousson (1876) was the first who described this species as Pupa ( Vertigo ) pygmaea var. nitidula based on material collected in Tabatsquri by G. Sievers. However, his description does not well characterize the species. It does not even well fit the syntypes ( Fig. 1 A; the size of this syntype is 1.9 mm x 1.0 mm; the other syntype is damaged). Nevertheless, there is no doubt about the authenticity of the syntypes, because there is only one sample of Pupa pygmaea var. nitidula in Mousson’s collection. There are no specimens of other Vertigo species from Tabatsquri in Mousson’s or in any other examined collection. The authenticity of the types gets further support from the fact that Boettger (1879) got conspecific specimens from the same locality from the same collector. The discrepancies between the type specimens and the description might be explained by Mousson’s insufficient optical equipment or his impaired vision as a result of his age. Disagreements between Mousson’s descriptions and his vouchers were also found in several other microsnails.

Although Boettger (1879) supposed that the Vertigo species from the type locality of Pupa pygmaea var. nitidula that he also got from G. Sievers is identical with the taxon described by Mousson (1876), he renamed it Pupa (Vert igo) sieversi . This name was used for the species by most of the later authors. Pilsbry (1919) noted that he was not sure whether the name nitidula should be rejected. He mentioned Tornatella nitidula Lamarck, 1816 , which is today included in Pupa Röding, 1798. However, Pupa pygmaea var. nitidula Mousson, 1876 is not homonymous with Pupa nitidula ( Lamarck, 1816) , because it has been established in the homonymous genus Pupa Draparnaud, 1801 and homonymy between identical species-group names in combination with homonymous generic names established for different nominal genera is to be disregarded (Art. 57.8.1. ICZN).

Pupa pygmaea var. nitidula Mousson, 1876 has been considered a synonym of V. substriata ( Jeffreys, 1833) by Schileyko (1984), Sysoev & Schileyko (2005), Egorov (2008) and Sysoev & Schileyko (2009). However, a reexamination of the syntypes of Pupa pygmaea var. nitidula Mousson, 1876 from Tabatsquri ( Fig. 1 A) confirmed the supposition of Boettger (1879) that this taxon is synonymous with his Pupa sieversi .

Although Pupa pygmaea var. nitidula Mousson, 1876 has not been used as a valid name after its original description, it is not a nomen oblitum in the sense of Art. 23.9 ICNZ because Pupa sieversi Boettger, 1879 has not been used as the presumed valid name of that taxon in 25 works in the past 50 years. Actually, a survey of more than 360 works containing data about Caucasian land snails resulted in only 11 works from the past 50 years citing V. sieversi as presumed valid name. Although we cannot exclude that there are a few additional papers, in which this name has been used as presumed valid name, it is very unlikely that the actual number of uses exceeds 24. Thus, the valid name of the species is Vertigo (Vertigo) nitidula ( Mousson, 1876) .

Boettger (1879) introduced two different spellings for a variety of Pupa sieversi : punctum and punctulum. By using the spelling Pupa (Vertigo) sieversi var. punctum as valid, Boettger (1880) determined that this is the correct spelling (Art. 24.2.4 ICZN). Pupa (Vertigo) sieversi var. punctulum is therefore an incorrect and, thus, unavailable spelling. The selection of punctulum as the correct spelling by Pilsbry (1919) is not valid as a result of the implementation of Art. 24.2.4 ICZN in the present edition of the Code.

Type material. Georgia, Mtskheta-Mtianeti region: Kazbek (syntypes of P. sieversi var. subalpestris SMF 2121/2, 2122/1; syntypes of P. substriata var. mitis SMF 2023/3); Samtskhe-Javakheti region: Borjomi: Kura debris (syntype P. of sieversi var. punctum SMF 4595/1); Abastumani, 41°45'N 42°50'E (syntypes of P. substriata var. mitis SMF 2282/1, 2289/2); Tabatsquri, 41°40'N 43°37'E (syntypes of P. pygmaea var. nitidula ZMZ 514689/ 2; syntypes of P. sieversi SMF 2029/1, 2030/10); Kvemo Kartli region: Manglisi, 41°42'N 44°23'E (syntypes of P. sieversi var. punctum SMF 2125/1, 245965/3).

Additional material. Russia, Krasnodar kray: debris of Psekups river ( Rosen 1907); Lagonaki plateau, rocks behind Hotel Azish-Tau near Pereval Azishsky, 44°05'04"N 40°00'49"E, 1770 m a.s.l. ( ZMH 100110 /2).—Adygea: Lagonaki plateau, source of the Kurdzips River, 44°05'N 39°59'E ( ZIN 37/1); Lagonaki plateau, source of the Kurdzips River, 44°03'N 39°59'E ( ZIN 36/15); Lagonaki plateau, source of the Kurdzips River, 44°03'N 40°01'E ( ZIN 35/6, 41/9); Lagonaki plateau, 44°03'N 39°59'E, 1800 m a.s.l. ( ZIN 23/1); Lagonaki plateau, Murzikal, near the Triangulation station, 44°02'N 39°59'E, 2180 m a.s.l. ( ZIN 34/9); Oshten Fisht mountains ( SMF 2123/3, voucher to Boettger 1889); Oshten Fisht mountains, glacial moraine between Oshten and Pshekha-su mountains, 43°59'N 39°53'E ( ZIN 40/4); Oshten Fisht mountains, high-mountain valley between Fisht and Pshekha-su mountains, 43°58'N 39°54'E ( ZIN 39/1); Oshten Fisht mountains, SE slope of the Armyansky mountain range, 43°58'N 39°57'E ( ZIN 38/1); Guzeripl 10 km towards Abago Pasture, 43°57'N 40°12'E ( ZIN 18/22); Abago Pasture, birch forest, near lodge " 14 km ", 43°56'N 40°13'E ( ZIN 19/48).—Karachayevo-Cherkesiya: Nizhnyaya Teberda, 43°38'N 41°53'E ( ZMH 80615/7); Arkhyz, near the mouth of Baritov river, 43°34'30”N 41°16'30”E ( ZMMU Lc-27359/2); 21 km SW of Arkhyz, 1 km SW of the confluence of Psysh and Aman-auz rivers, 43°27'N 41°10'E ( ZMMU Lc-27356/5, vouchers to Sysoev & Schileyko 2009, as V. substriata ; ZMMU Lc-27378/3); Dombay valley in direction to Alibek glacier, 43°18'N 41°35'E ( ZMH 80617/3); Teberda, 43°27'N 41°45'E ( SMF 2132/3, voucher to Boettger 1883; SMF 54027/2, 54028/3; ZIN 1/1, voucher to Boettger 1883; ZIN 2/2, 3/1, 4/1; ZMZ 514740/2); Teberda valley, Madniskhevi, 43°27'N 42°05'E (SCZENASRA/6).—Kabardino-Balkariya: Zhankhoteko, 43°33'N 42°12'E ( ZIN 29/1); Shashbavat gorge below Tyrnyauz, 43°25'N 42°57'E ( ZMH 80616/1); Bukhaidze, 43°19'N 42°45'E ( ZIN 30/1); Itkol, forest in gorge at Mount Cheget, 43°15'N 42°34'E ( ZMH 80613/2); lower Adylsu valley, 43°14'N 42°39'E ( ZMH 80612/13); Chegem gorge 5 km S of Verkhniy Chegem village, 43°13'N 43°04'30''E ( Sysoev & Schileyko 2009).—North Ossetia: Nizhniy Nar, 42°59'N 43°47'E ( ZIN 31/1); Dzinaga, 42°54'N 43°42'E ( ZMMU Lc-27357/5); Chmi, 42°51'N 44°38'E ( ZIN 22/20).—Ingushetia: Armkhi, 42°48'N 44°43'E ( ZIN 28/2).—Chechnya: Lake Kezenoyam ( ZIN 32/2, 33/1).

Georgia, Abkhazia: Sukhumi Military Road, near Mount Pal, Bogatskiye Skali, 43°02'N 41°22'E ( ZIN 7/ 2).—Imereti region: Nakerala pass, 42°22'56''N 43°01'06''E ( NHMW /1, voucher to Pokryszko et al. 2011).—Shida Kartli region: Tqemlovana, 41°51'30''N 43°43'00''E ( Lezhawa 1973, as V. substriata ).—Mtskheta-Mtianeti region: Kazbek (ZMZ 514683/2); valley of Andaki river 2.2 km upstream of its confluence with the Argun river, 42°39'08''N 45°11'28''E (FW 36/5); Stepantsminda (= Kazbegi), 42°39'N 44°39'E ( ZIN 26/5); gorge of Argun river between Shatili and Georgitsminda, 42°38'15''N 45°08'34''E (FW 37/1); Sioni, 42°36'N 44°35'E ( ZIN 25/23); Kobi, 42°33'N 44°30'E ( ZIN 27/25); Kumlistsikhe, 42°27'N 44°29'E ( ZIN 21/8).—Tbilisi: Tbilisi, 41°42'N 44°50'E ( SMF 54026/1).—Kakheti region: Dzhvarboseli, 42°25'N 45°30'E (IUC 388/n, voucher to Lezhawa 1962, 1973, as V. substriata ); Verkhne Omalo: banks of Tushetski Alazani river, 42°22'N 45°38'E ( Lezhawa 1962, as V. substriata ); Akhmeta, 42°02'N 45°12'E ( Lezhawa 1973, as V. substriata ); Qvareli, 41°57'N 45°49'E ( Lezhawa 1973, as V. substriata ); Lagodekhi, 41°54'N 46°20'E ( ZIN 8/1).—Samtskhe-Javakheti region: Borjomi, Banikhevi valley, 41°52'N 43°23'E ( ZIN 5/1); Abastumani, 41°45'N 42°50'E ( SMF 2127/3, voucher to Boettger 1886a); Sapara Monastery, 41°36'N 43°02'E ( ZIN 20/1); Vardzia 2 km towards Tmogvi, 41°22'56"N 43°17'51"E, 1240 m a.s.l. ( ZMH 100687 /3); canyon of Kura river near Vardzia, 41°22'N 43°15'E ( ZIN 6/1).—Kvemo Kartli region: Martqopi, 41°47'N 45°01'E ( Boettger 1880); Manglisi, 41°42'N 44°23'E ( SMF 2124/51; IZPAN); Tsqneti, 41°42'N 44°42'E ( Lezhawa 1966, 1973, as V. substriata ); Betania monastery, 41°41'30''N 44°36'40''E ( Lezhawa 1966, as V. substriata ); Rekha, 41°41'N 43°51'E ( Lezhawa 1966, 1973, as V. substriata ); Kojori 41°40'N 44°42'E (IUC 403/2, voucher to Lezhawa 1966, as V. substriata ); Akhalsopeli, 41°39'00''N 44°20'30''E (IUC 394/4, voucher to Lezhawa 1966, 1973, as V. substriata ); Kiketi, 41°39'N 44°39'E ( Lezhawa 1966, 1973, as V. substriata ).

Armenia, Shirak Province: Ashotsk (= Gukasyan), Akhuryan gorge, 41°02'15''N 43°51'30''E (SCZENASRA/ 11); Amasia, 40°57'N 43°47'E ( Akramowski 1976).—Tavush Province: Ijevan, 40°53'N 45°09'E (SCZENASRA/ 2); Ijevan, Tissovaya Forest (SCZENASRA/1); Gandzakar: middle part of S slope of Mount Budur, 40°50'30''N 45°10'30''E ( ZMMU Lc-27381/2); Dilijan, left bank of Agstafa river ( ZMMU Lc-7654/11, 7655/26); Dilijan, Shamakhyan, 40°45'45''N 45°50'10''E (SCZENASRA/1); Dilijan, Papanino, 40°44'30''N 45°50'45''E (SCZENASRA/2).—Kotayk Province: Tsaghkadzor, Mount Teghenis, 40°32'N 44°39'E ( ZMH 80614/22); Tsaghkadzor, 40°32'N 44°43'E ( Akramowski 1968).—Gegharkunik Province: Tsapatagh (= Babadzhan), 40°24'30''N 45°28'30''E (SCZENASRA/1).—Ararat Province: Khosrov Forest, 40°02'N 44°55'E (SCZENASRA/ 1).—Syunik Province: Tatev, 39°23'00”N 46°14'30”E ( ZMMU Lc-22197/1, 27358/10); Kajaran, 39°09'N 46°09'E (SCZENASRA/2).

Azerbaijan: Zaqatala State Reserve, Mount Ağkiman, 41°49'N 46°31'E ( ZIN 17/1); Zaqatala State Reserve, Mount Vergetel, near ledge, 41°44'N 46°26'E ( ZIN 16/27); Qusar, 41°26'N 48°26'E ( SMF 2128, voucher to Boettger 1886b); Şəki, Kiş river, 41°16'N 47°12'E ( ZIN 24/4); western branch of Kürəkçay river near fish-factory, 40°26'N 46°19'E ( ZIN 11/5); road to Lake Göygöl 1 km before the lake, 40°25'30”N 46°20'00”E ( ZIN 14/17); road to Lake Göygöl, 2 – 3 km before fish-factory, 40°25'N 46°19'E ( ZIN 15/115); north shore of Lake Göygöl, 40°25'N 46°20'E ( ZIN 13/3); mountain range between Toğanalı and Lake Göygöl, 40°24'N 46°19'E ( ZIN 9/1); Mount Kəpəz, 40°21'N 46°21'E ( ZIN 10/2); mountain Sağsağan Qayası, 39°58'N 46°36'E ( ZIN 12/1); Lerik, 38°46'N 48°25'E ( SMF 2126/2, voucher to Boettger 1886a); Lǝnkǝran, 38°45'N 48°51'E ( Boettger 1886a).

Habitat. The species lives mainly in deciduous or mixed mountain forests, but occurs also in fissures of rocks in the subalpine zone above the timberline as well as under Rhododendron shrubs.

Distribution ( Fig. 3 ). Vertigo nitidula is widely distributed in the Caucasian region, occurring on both sides of the Great Caucasus as well as in the Lesser Caucasus and the Talysh Mountains. The occurrences in the Lesser Caucasus and in the Talysh Mountains in southern Azerbaijan indicate that the range of V. nitidula probably extends into Turkey and Iran.

Figures

FIGURE 1. Vertigo spp., shells. A – O. Vertigo (Vertigo) nitidula (Mousson). A. Georgia: Tabatsquri (syntype of P. pygmaea var. nitidula ZMZ 514689). B. Georgia, Tabatsquri (syntype of P. sieversi SMF 2129). C. Georgia, Manglisi (syntype of P. sieversi var. punctum SMF 2125). D. Georgia, Kazbek (syntype of P. sieversi var. subalpestris SMF 2122). E. Georgia, Abastumani (syntype of P. substriata var. mitis SMF 2282). F – G. Georgia, Kobi (ZIN 27). H – J. Russia, lower Adylsu valley (ZMH 80612). K – O. Armenia, Tsaghkadzor, Mount Teghenis (ZMH 80614). P – V. Vertigo (Vertigo) substriata (Jeffreys). P. Germany, Nübel (ZMH 60278); Q. Russia, Zilairskoe plateau, Novoaleksandrovka (ZMH 96098). R. Russia, Altai Republic, 2 km W of Zaisanskaya Elan (ZMH 96096). S. Russia, Chegem valley (ZIN 96). T – V. Georgia, Kobi (ZIN 95). Scale bar = 0.5 mm.

FIGURE 2. Variation in shell size and shape of Vertigo (Vertigo) nitidula (Mousson).

FIGURE 3. Distribution of Vertigo (Vertigo) nitidula (Mousson) (dots) and Vertigo (Vertigo) substriata (Jeffreys) (stars) in the Caucasus region (0.5 ° grid).