Acicula parcelineata ( Clessin, 1911 )

Páll-Gergely, Barna, Mumladze, Levan, Grego, Jozef & Giokas, Sinos, 2023, The genus Acicula W. Hartmann, 1821 in the Caucasus (Gastropoda: Caenogastropoda: Aciculidae), Zootaxa 5239 (4), pp. 451-476 : 461-463

Acicula parcelineata ( Clessin, 1911)

( Figs. 8 , 10 )

Acme parcelineata Clessin, 1911: 165 .

Acicula bakanense Steklov, 1966: 122 , pl. 1, fig. 11.

Acicula parcelineata — Boeters et al. 1989: 78, figs 77, 78.

Diagnosis. A small (H: 2–2.4 mm), mostly conical Acicula species with few and irregularly arranged longitudinal grooves and without neck bulge.

Number of grooves on last whorl. 3–11, average: 5.56 (SD=+/-1.6) (n = 34).

Measurements (in mm). H: 1.62–2.68, average: 2.04 (SD=+/-0.32); D: 0.64–0.91, average: 0.76 (SD=+/- 0.09); D/H: 0.32–0.41, average: 0.38 (SD=+/-0.02) (n = 34).

Material examined. GEORGIA, Samegrelo Reg., Mukhuri vicinity, road to Lugela, small karst spring well just at left side of road from Mukhuri to Lugela , behind Shurubumu springs, 42°38.985′N 42°12.300′E (locality code: 2021/28x), leg. J. Grego & M. Szekeres, 17 October , 2021, 1 figured shell (H: 2.39 mm, D: 0.88 mm) (coll. JG); Imereti, Nakhriduri 5 spring cave of Turchu Gamosadivari river at the end of the canyon (locality code: 2018/17), 42°29.216′N, 42°31.341′E, leg. J. Grego & L. Mumladze, 3 May , 2018, 1 shell (H: 2.03 mm, D: 0.76 mm) (coll. JG); Imereti reg., Tkibuli , Tkibuli-Nikortsminda road left side, spring with travertine waterfall (locality code: 2018/19), 42°22.976′N 43°0.730′E, leg. J. Grego & L. Mumladze, 4–8 May 2018, 6 shells (H: 2.23–2.34 mm, D: 0.85–0.87 mm) (coll. JG); Imereti reg., Tskhradjvari pass, limestone rocks and karst forest (locality code: C2458), 42°23.405′N, 42°58.421′E, leg. J. Grego, 4 May 2018, 2 shells (coll. JG); Imereti reg., Sairme gorge, 1925 m a.s.l., 41°51.386′N, 42°47.406′E (locality code: sp8s3), leg. L. Mumladze, 11 October 2013, 1 shell ( ISU); Imereti reg., Kinchkhaperdi vicinity, Okatse , spring at left bank of Satsiskvilo river canyon, leakage among larger stones, 42°31.102′N, 42°33.437′E (locality code: F1940), leg. J. Grego & M. Szekeres, 15 October , 2021, 2 dry shells (coll. JG); Samegrelo reg., Tekhuri River valley , 465 m a.s.l., 42°36.035′N, 42°20.797′E (locality code: leb3), leg. L. Mumladze, 21 August 2015, 2 subadult shells ( ISU); Samegrelo reg., Chkvaleri vicinity, Kvatsalara, small cave spring just left side of the road, to Intsira waterfall, 42°43.275′N, 42°5.498′E (locality ode: F1968), leg. J. Grego & M. Szekeres, 19 October, 2021, 1 broken shell (coll. JG); Georgia, Imereti reg., Satsiskvilo vicinity, Turchismta, concrete wall and natural outlets among limestone beds at right side of path from Satsiskvilo to Okatse Spring (locality code: 2021/26), 42°29.821′N, 42°32.827′E, leg. J. Grego & M. Szekeres, 15 October, 2021, 1 broken shell (coll. JG) . RUSSIA, Western Caucasus, vicinity of Sochi, valley of the Khosta river , at Rassvet village , flotsam of Khosta , 43°32.856′N, 39°52.892′E, leg. L. Németh, 20 June 1988, 68 j/b shells + 22 adult shells ( LN 10680 ); Abkhazia, Novij Afon (Akhali Athoni), above the tunnel near the railway station, 43°5.518′N, 40°48.938′E, leg. L. Németh, 16 June 1988, 1 broken shell ( LN 10524 ); Western Caucasus , valley of River Mzimta towards Krasnaya Polyana, 26/33. km, in the "gorge" (approximate GPS coordinates: 43°31.267′N, 39°59.903′E), leg. L. Németh, 18 June 1988, 3 shells ( LN 10563 ); Western Caucasus , valley of River Dagomysi , ca. 10 km, vicinity of “Nor Luis village” (=Altmets), approximate GPS coordinates: 43°43.333′N, 39°40.500′E, river debris, leg. L. Németh, 19 June 1988, 7 shell fragments ( LN 10720 ); Western Caucasus , vicinity of Sochi, valley of the Khosta river , at Rassvet village , flotsam of Khosta, 43°32.856′N, 39°52.892′E, leg. L. Németh, 20 June 1988, 12 juvenile /broken + 8 adult shells (ex LN 10681) .

Differential diagnosis. Acicula moussoni was found syntopically with A. parcelineata at six sites (LN10561- LN10680-LN10681, sp8s3, F1968, 2021/26, F1940, 2021/28x, see Appendix Figures 1–3 ) without intermediate forms, which indicates that in spite of the close similarity, they are distinct species. The shell differences are the following: A. moussoni is generally darker and larger (although the size ranges largely overlap, see Appendix Fig. 3 ), which is the most important trait that helps distinguish the two species in the case of mixed samples. Furthermore, A. parcelineata is rather conical or cylindrical, i.e., the sides of the shell are straight; the whorls grow regularly. In contrast, A. moussoni is rather ovoid-spindle-shaped. The whorls are flatter (less bulging) in A. parcelineata than in A. moussoni . Lastly, A. parcelineata has generally fewer grooves above the aperture, and they are arranged less regularly than those of A. moussoni (i.e., between two grooves, where a third one would be expected if it was regularly arranged, the intermediate one is absent).

Distribution. Acicula parcelineata is known from the northern half of the Greater Caucasus Mountains, and one locality is known in the Lesser Caucasus Mountains ( Fig. 7 ).

Remarks. This species was originally described from 'Dzingelau' (Dzięgielów in southern Poland), and was subsequently reported from Czech Republic, Romania, Slovakia and the Carpathian part of Ukraine ( Jackiewicz 1974; Boeters et al. 1989; Horsák et al. 2013). Boeters et al. (1989) also reported it from flotsam of the river Rioni at Poti, Georgia, and mentioned that Jackiewicz (1974) reported it from North Ossetia in the Caucasus. Jackiewicz (1974), in fact, referred to a paper by Kalitina and Botcharova (1971), in which they collected molluscs from the mountain part of North Ossetia (= Republic of North-Ossetia-Alaniya). Those authors cited three localities where the land snails were collected (the Ardon and Kurtaty gorges, and the Military-Georgian [= Voenno-Gruzinskaya] Road near Lars settlement). Unfortunately, it is not specified where A. parcelineata was collected. Furthermore, Acicula bakanense Steklov, 1966 , which was treated as a synonym of A. parcelineata by Boeters et al. (1989) and Egorov & Greíe (2003), was described from the Mio-Pliocene at Upper Bakanskaya (Krasnodar, North Caucasus). Based on this information, Boeters et al. (1989) speculated that A. parcelineata may have a wide distribution in the Caucasus Mountains. The data presented herein partly proves this claim. Namely, A. parcelineata was only found in the northern half of the Caucasus Mountains, but the multiple newly reported sites show that this species is widespread and not rare in the area where it occurs.

Figures

FIGURE 1. A: An Acicula shell positioned with the axis of the shell on the y-axis and the aperture in the same plane as the objective, showing the location of the 18 landmarks used. B: counting of grooves on the last whorl. Images not to scale. Photos: B. Páll-Gergely.

FIGURE 2. Means ± 95% Confidence Intervals of (A) Log centroid size, and (B) of the number of grooves, for the studied Acicula species, based on landmark data.

FIGURE 3. (A) Principal Components Analysis and (B) Canonical Variates Analysis for the studied Acicula species, and the ordinations of specimens, with 90% confidence ellipses, based on landmark data.

FIGURE 7. Distribution of Acicula species in the Caucasus Mts. The symbols marked with numbers (1: Surami range, 2: Manglisi, 3: Martkopi, 4: North Ossetia) do not represent georeferenced localities for Acicula moussoni O. Boettger, 1879 and Acicula parcelineata (Clessin, 1911).

FIGURE 8. Acicula parcelineata (Clessin, 1911). A: 2018/19, specimen1; B: 2018/19, specimen2; C: 2018/17, specimen 1; D: ex LN 10681, specimen2; E: 2021/28x; F and G: shells collected near Tatariv village, Ukraine, photos from Skvortsova & Balashov (2019); H: ex LN 10680, specimen1; I: ex LN 10680, specimen2. All photos: B. Páll-Gergely.

FIGURE 10. Synoptic view of Caucasian Acicula. Upper left shell: Acicula limbata Reuss, 1861; other shells in the upper two rows: Acicula moussoni O. Boettger, 1879, third row: Acicula telum Páll-Gergely, n. sp., fourth row: Acicula parcelineata (Clessin, 1911).