Acicula moussoni O. Boettger, 1879

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 : 457-461

Acicula moussoni O. Boettger, 1879

( Figs. 5B–F , 6 , 10 )

Acicula moussoni Boettger, 1879: 41 , pl. 1 fig. 7. Type locality: “am Kazbek” [may be erroneous, see under "Selection of a neotype "].

Acicula moussoni — Boettger 1880a: 148.; Boeters et al. 1989: 72, fig. 55 (partim; Fig. 72 is A. telum n. sp.); Kantor & Sysoev 2005: 41; Sysoev & Schileyko 2009: 11, 249, fig. 2A; Egorov & Greíe 2003: 15, map 7; Neiber et al. 2021: 27, fig. 5.

Acicula limbata — Boeters et al. 1989: 56, Fig. 56 (partim, treats the Czech Miocene species conspecific with A. moussoni ); Egorov & Greíe 2003: 17, fig. 9, map 6; Kantor & Sysoev 2005: 41; Sysoev & Schileyko 2009: 11, text-fig. 1; Pokryszko et al. 2011: appendix 3; Mumladze et al. 2017: appendix S5.

Acicula (Acme) moussoni — Boettger 1880b: 159.

Acme moussoni — Clessin 1881: 134; Boettger 1883: 191; Kobelt 1894 in 1894-96: 12, pl. 183 fig. 1153; Rosen 1905: 54; Rosen 1911: 132; Kalitina 1954: 11; Kalitina 1958: 172; Lezhawa 1966: 9; Javelidze 1972: 18, fig. 7; Lezhawa 1973: 22.

Pupula moussoni — Hesse 1920: 88.

Acicula (Acicula) moussoni — Zilch 1976 b: 127, pl. 12 fig. 14; Kijashko 2000: 21.

Material examined. GEORGIA: Ud. S. S. R.: Kaukasus, "Radscha" ( Racha mountains ), leg. H. Leder, 1889 ( SMF 23858 /2, photos of a shell were received from Frank Walther) ; Georgian Military Road, 2300 m a.s.l., Cross ( Jvari ) pass, Narzani fountain (approximate GPS coordinates: 42°31.900′N, 44°28.340′E), leg. L. Németh, 6–7 July 1988, 4 broken shells ( LN 10191 ) ; 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, 4 broken shells, (coll. JG) ; 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) ; 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, 1 specimen in ethanol, neotype (hereby designated), H: 2.48 mm, D: 0.95 mm ( ISU TM-T004 -N) ; Abkhazia, Iupshara gorge (approximate GPS coordinates 43°26.470′N, 40°32.085′E), leg. L. Németh, 14 June 1988 ( LN 10782 ) ; Imereti reg., Sairme gorge, 1818 m a.s.l., 41°51.960′N, 42°46.840′E, (locality code: sp7s2), leg. L. Mumladze, 11 October 2013, 2 subadult shells + 1 juvenile shell ( ISU) ; 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) ; Kakheti reg., Lagodekhi Protected Areas , subalpine forest edge, 2347 m a.s.l., 41°52.445′N, 46°22.726′E, (locality code: lp10s1), leg. L. Mumladze, 3 June 2013, 1 shell ( ISU) ; Abkhazia, valley of the Bzipi and Iupshara, road leading to Lake Ritsa , double tunnel (approximate GPS coordinates: 43°23.092′N, 40°27.922′E), leg. L. Németh, 14 June 1988 ( LN 10801 ) ; Imereti reg., Sairme gorge, subalpine forest edge, 2210 m a.s.l., 41°50.812′N, 42°48.447′E (locality code: sp9s3), leg. L. Mumladze, 11 October 2013, 1 corroded shell ( ISU) ; 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 adult specimen in ethanol + 1 adult + 2 juvenile dry shells (coll. JG) ; Mtskheta-Tianeti reg., Upper Iori River valley , 1470 m a.s.l., 42°18.632′N, 45°7.372′E, (locality code: Iori 1), leg. L. Mumladze, 1 August 2010, 2 shells ( ISU) ; Kakheti reg., Lagodekhi Protected Areas , 1815 m a.s.l., 41°51.505′N, 46°20.477′E (locality code: lp7s3), leg. L. Mumladze, 3 June 2013, 2 shells ( ISU) ; Kakheti reg., Lagodekhi Protected Areas , 1215 m a.s.l., 41°50.950′N, 46°19.475′E, (locality code: lp4s2), leg. L. Mumladze, 3 June, 2013, 5 shells (3 completely adults) ( ISU) ; Kakheti reg., Lagodekhi Protected Areas , 803 m a.s.l., 41°51.476′N, 46°18.628′E (locality code: lp2s3), leg. L. Mumladze, 3 June 2013, 4 shells ( ISU) ; Guria reg., Ozurgeti , anthropogenic site, 57 m a.s.l., 41°56.096′N, 41°59.258′E (locality code: E25D5P1), leg. L. Mumladze, 9 September 2018, 1 shell in ethanol ( ISU) ; Kakheti reg., Lagodekhi Protected Areas , 1297 m a.s.l., 41°50.938′N, 46°19.883′E (locality code: lm007), leg. L. Mumladze, 20 August 2010, 2 subadult, corroded shells + 4 juveniles ( ISU) . RUSSIA, 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 ( LN 10651 ) ; Russia, 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 ( LN 10680 ) ; Orjonikidze (= Vladikavkas), beginning of Georgian Military Road , leg. L. Németh, 26 July 1988 ( LN 7767 ) .

Number of grooves on last whorl. 4–14, average: 8.25 (SD=+/-2.6) (n = 36).

Measurements (in mm). H: 1.75–3.06, average: 2.44, (SD=+/-0.36); D: 0.66–1.26, average: 0.94 (SD=+/- 0.14); D/H: 0.34–0.43, average: 0.39 (SD=+/-0.02) (n = 33).

Differential diagnosis. See under A. parcelineata and A. telum n. sp.

Intraspecific variability. The populations of this species show some variability in terms of shell size and groove density. A few shells (e.g. Figs. 5B , 6F ) possess a thin neck bulge, and in some cases (e.g. Fig. 6B ) it is difficult to decide whether a neck bulge is present or the visible slender swelling is a result of a groove situated close to the peristome. Furthermore, some shells of a single population may exhibit a thin neck bulge, while others do not. Furthermore, it seems that while in smaller A. moussoni shells the individual grooves on the last whorl (above the aperture) are of comparable depth and are more or less regularly arranged (e.g. Figs. 5F , 6E, F ), in larger shells some of the grooves are weaker than others and the spaces between them are more variable (e.g. Figs. 6B–D ).

Distribution. Acicula moussoni is known from the entire range of the Caucasus Mountains ( Fig. 7 ).

Remarks. This species was called A. limbata by Boeters et al. (1989) and since. We examined shells of the real Acicula limbata from the Early Miocene of the Czech Republic (NHMW 2013/0572/0004, Most Basin, Bohemia, Burdigalian; see Harzhauser et al. 2014) and concluded that besides the slightly thicker peristome and the more rounded aperture (i.e. the parietal region is more curved than in the Caucasian shells), the fossil shells do not differ from the Caucasian extant species. There are several examples (e.g. Domokos et al. 2018, but even in Aciculidae , see Gittenberger 1990) when Miocene and extant distributions of the same species are different, but in those cases the fossil and current distributions are not very disjunct with an enormous geographic gap between them. In the present case, due to the huge geographic distance between Czechia and the Caucasus Mountains and the gap of records between the two areas, it is highly unlikely that a Central European Early Miocene species would be identical with an extant species restricted to the Caucasus Region. Moreover, finding only a few morphological differences is not surprising in such a character-poor group. Therefore, we use the name Acicula moussoni for the Caucasian extant species and restrict the name A. limbata for the Miocene fossil in Czechia.

A sample in the Senckenberg Museum ( SMF 23858 ) was labelled as " Acicula (Acicula) zilchi n. sp., holotype + paratype, det. Subai, 1978". It is probable that Péter Subai intended to describe it as a new species, but never did so.

Selection of a neotype. Boettger (1879) described A. moussoni based on two subadult specimens from "Kasbek" (Mt. Kazbek). Later, he stated that his material from Mt. Kazbek was mixed with material from the Surami mountain range. Thus, the occurrence of several species at Mt. Kazbek has to be confirmed ( Boettger 1880a). Unfortunately, specimens from Mt. Kazbek or from “Suram” were not found by Frank Walther in the SMF, where Boettger's collection is housed ( Dance 1986). We note that Boettger determined the material for Leder, who later sold the shells to collectors, however, Boettger usually kept material for himself (Frank Walther, pers. comm.). The designations of lectotypes from “Manglis” by Zilch (1976) and “Martkopi” by Boeters et al. (1989) are invalid because these were certainly not part of the type series. Besides the differing locality data, the measurements of the specimens, especially that of the lectotype designated by Zilch (1976), do not fit the shell size mentioned in the original description. Boeters et al. (1989: 74) considered the lectotype designated by them a syntype because “Martkopi” might be attributed to the Kazbek massif. However, Martqopi is separated from Mt. Kazbek by the main chain of the Greater Caucasus. The two alleged syntypes are probably the vouchers of Boettger (1880a) who mentioned two newly collected specimens from “Martkopi” in the year after the description of A. moussoni .

The question is which of the currently recognized Caucasian species was originally described as A. moussoni : was it the bullet-shaped species ( A. telum n. sp.) or one of the 'normal' species ( A. moussoni or A. parcelineata in the sense of this paper)? The description of Boettger (1879) is not sufficient to decide which of the two species he was referring to. The following arguments were considered: (1) The lithograph in the original description ( Boettger, 1879: 41, pl. 1 fig. 7) is more similar to the bullet-shaped species in shell shape, but the aperture shape is more similar to that of the 'normal' species. (2) The shell on the lithograph has relatively widely-spaced grooves on the penultimate whorl, which is more similar to the 'normal' species (especially A. parcelineata ), whereas A. telum n. sp. usually has more densely arranged grooves. (3) Clessin, who was more skilled with Acicula and had a large collection, compared A. moussoni with “native” (i.e. German) A. lineata . At that time, A. lineata and A. fusca were not separated, and it was not known before Steusloff (1939) that A. fusca was native to Germany. Boettger (1879) cited Clessin that the upper whorls of A. moussoni are more pointed and more conical and the whorls increase less rapidly. These characters fit much better to the 'normal' species than to the bullet-shaped new species. (4) Later, Boettger (1880a) cited specimens that from the measurements (H: 2 7 / 8 mm) belonged surely not to the bullet-shaped species (which is 1.89–2.41 mm in shell height), but Boettger noted no difference to A. moussoni (H: 2 mm according to the original description). Clessin had probably seen one or both type species of A. moussoni and nevertheless assigned a specimen of 3 mm to it ( Clessin 1881). (5) Zoogeographical considerations: Currently it seems that the bullet-shaped species is restricted to the northern part of the Caucasus, with the southern-most locality being the Tskhenistskali valley. In contrast, all historical material of A. moussoni were collected much more in the south (Mt. Kazbek, Surami, Martkopi), from where no A. telum n. sp. but only the 'normal' species were found.

This study revealed moreover that Boeters et al. (1989) united two Caucasian species (i.e., A. moussoni and A. telum n. sp. in this paper's sense) under the name Acicula moussoni . Namely, figure 55 of Boeters et al. (1989) shows a shell of A. moussoni , whereas fig. 72 shows an undescribed species here described as A. telum n. sp. Furthermore, there is an additional Caucasian species (herein called Acicula parcelineata ), which cannot be easily distinguished from A. moussoni . Consequently, there is an exceptional need for correction of the nomenclatural problem of Caucasian Acicula by designating a neotype for A. moussoni . The neotype designated herein has a spindle shaped shell and a prosocline aperture, which distinguishes it from all A. telum n. sp. specimens. The darker colour of the neotype, the spindle-shape instead of cylindrical shell, and more numerous grooves distinguishes it from A. parcelineata shells.

The neotype was collected ca. 160 km southeast from the type locality (Mt. Kazbek) and ca. 95 km from the Surami range (which may be the real locality at which the syntypes of A. moussoni were collected, see Boettger 1880a). However, these geographic distances are rather small compared to the extent of the distribution of A. moussoni (up to ca. 560 km across its distribution range). The reason why no shells collected closer to the type locality of the Surami range were selected as neotype is that all those shells were ca. 3 mm, whereas the original description mentions 2 mm only.

Figures

FIGURE 5. Shells of Acicula species. A: Acicula limbata Reuss, 1861 (NHMW 2013/0572/0004). B–F: Acicula moussoni O. Boettger, 1879. B: SMF 23858a (labelled as “Acicula (Acicula) zilchi n. sp.”); C: SMF 23858b (labelled as “Acicula (Acicula) zilchi n. sp.”); D: LP2S3, specimen1; E: “Lectotype” of Acicula moussoni O. Boettger, 1879 (invalidly designated, SMF 4202a); F: F1940, specimen1 (ISU TM-T004-N, neotype, hereby designated). Photos: B. Páll-Gergely (A, C, D, F) and F. Walther (C, E).

FIGURE 6. Acicula moussoni O. Boettger, 1879. A: Iori1, specimen1; B: LP4S2, specimen1; C: LP7S3, specimen1; D: LN 7767, specimen1; E: LN 10651, specimen1; F: LN 10680, specimen1. All photos: B. Páll-Gergely.

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 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).