Pelias tuniyevi Ananjeva, Gabaev, Iremashvili, Lotiev, Petrova, 2021

Ananjeva, N. B., Gabaev, V. N., Iremashvili, G. N., Lotiev, K. Yu. & Petrova, T. V., 2021, The taxonomic status of the vipers of the Pelias (kaznakovi) complex in the middle-flow of the Kura River basin in the East Transcaucasia, Proceedings of the Zoological Institute of the Russian Academy of Sciences 325 (1), pp. 3-33 : 16-31

Pelias tuniyevi Ananjeva, Gabaev, Iremashvili, Lotiev, Petrova sp. nov.

Holotype. SNP No 937, adult male, SO, Znaur District, vicinity of Kharisdzhin V. (=Tormaneuli V.), 42.2504°N, 43.8398°E, 1010 m above sea level, 14.05.2014, collector G. Khasity ( Fig. 7 ).

Paratypes. Twelve specimens: SNP 1054 (1 adult female and 1 juvenile male, 7 born in terrarium), Ge , Shida-Kartlis Territory , Khashuri District , Tashiskari V., 41.5704°N, 43.3010°E, 720 m asl, 09.2015, Coll. Z. Khachidze; 936 (adult male), SO, Kharisdzhin V., 23.04.2014, Coll. G. Khasity; 915 (adult male), SO, Tskhinval District, vicinity

Notes: Statistically significant differences are highlighted in bold.

of Atsriskhevi V., 42.2970°N, 44.2238°E, 1325 m asl, 23.09.2012, Coll. E.E. Komarov ; 1182 (adult female) (the same as holotype); 1140 (adult female), Ge , Tashiskari V., 22.10.2017, Coll. G.N. Iremashvili ; 1086 (adult female), vicinity of Atsriskhevi V., 18.08.2016 , Coll. V. V . Tikhonov ; 951 (adult female), Kharisdzhin V., 14.05.2014, Coll. G. Khasity ; 1935 (adult female), SO, Tskhinval District , vicinity of Uanat V. (= Vanati V.) , 42.2867°N, 44.0535°E, 1013 m asl, 03.09.2018, Coll. Ch.B. Bukulov; 1095 (juvenile

Notes: Statistically significant differences are highlighted in bold.

female), vicinity of Atsriskhevi V., 07.09.2016, Coll. V. V. Tikhonov; 1079 (juvenile female), vicinity of Atsriskhevi V., 18.08.2016, Coll. V. V. Tikhonov; 930 (juvenile female), SO, Dzau District , Gufta V. (=Didi Gupta V. – Patara Gupta V.): 42.3592°N, 43.8892°E, 1060 m asl, 05.08.2019, Coll. V.N. Gabaev ( Fig. 8A–F ) .

Diagnosis. Small-sized snake, males differ from all representatives of Pelias kaznakovi s.l. by minimal values of total length, length of pileus, width of head, numbers of ventral and subcaudal shields, and shields around eyes; females have minimal body length, length of pileus, width of head, number of shields around eyes and loreals, number of zigzag wings. The vipers of both sexes from the left-bank basin of the middle flow of the Kura River differ from all other compared vipers by small sizes and the minimum number of shields around the eyes. The dorsal surface of the males is beige-gray, yellowish-gray, rarely brownish-reddish, or yellow; the dorsal surface of the females is pinkish-gray, light brown, gray-yellow or melanistic. The majority of females has a weakly undulated zigzag pattern ranging in color from light- to dark-brown; the zigzag pattern of males is black or brown-black, with sharp wings and occasional interruptions. The throat in both sexes is light-colored, the belly is usually gray-spotted against a dark background; the lower part of the tail in both sexes is pinkish with varying numbers of dots in males and without dots in females.

Description of the holotype. Adult male having the following morphological characters: total length (T.l.)– 382 mm, length of tail (L. cd) – 52 mm; 3 preventrals; 128 ventrals; 35 subcaudals. The rostral and the preanals that lie on either side of the rostral come to the upper surface of the head, so that the rostral acts simultaneously as an apical shield, and the prenasals act as canthals; there are therefore 7 canthal shields. Length of pileus (Pil.) – 12.0 mm. Rostral index – 72.27. Crown shields (C.s.) – 14. The upper preocular shield is separated from the nasal (In.) by the upper loreal and posterior canthal shields on either side of the head. 21 rows of dorsal scales around the neck and at the midbody, and 19 at posterior part of the body, 21 sublabials in sum, 10 supralabials on the right and 9 on the left side 11/11 shields around eyes; 160 wings of zigzag, 6 loreals on either side. Length of the head – 20.8 mm, width – 11.9 mm, height – 8.6 mm. Frontal and parietal shields are not divided. Between the frontal and large upper oculars: 1 shield on the right and 2 on the left side. Supralabials are white, the 5 anterior ones on either side are thickly pigmented by small red-brown nettles, posteriors – without pigmentation, or contrasted two-color black-and-white. The holotype specimen is beige-grey from above, zigzag almost uninterrupted dark brown-black. The zigzag is connected to the dark W-shaped pattern of the head. The front part of the head is entirely black with gray edging of the upper oculars. On either side of the body is a row of large patches of the same color as the zigzag. Coloring of the throat is light; the belly is grey-spotted on a dark background, the lower part of the tail is dark spotted on a pinky background, the tip of the tail is light pink.

Description of the paratypes. The paratypes correspond to the description of the holotype with insignificant variations in size and meristic characters ( Table 17). It should be noted that the female (No. 1086) from Atsriskhevi has a combination of pholidosis in the front of the head, with 7 canthals, similar to that of the holotype. Five paratypes have 2 apicals, four – 1 broad apical and two – 1 narrow apical. The majority of paratypes have 21 scales around the middle of body; two specimens have 19 and 22 scales, respectively. Upper preocular shield is separated from the nasal by the upper loreal in all paratypes.

Color patterns are very diverse. The main background of adults and young males is beige-gray, yellowish-gray, rarely brownish-reddish, or yellow; females – pinkish-gray, light brown, gray-yellow, and some specimens are melanistic. The zigzag in most females is wider than in the males, almost continuous, undulate, colored light brown, pink-brown, or dark brown, sometimes with dark brown wings; in the males the zigzag, regardless of width, has sharp wings, is black, or brown-black in color and sometimes disjunct. In young and semi-adult individuals, the zigzag is not different from the zigzag of adult animals, and the color is less bright. The color pattern of the pileus is more pronounced in males. On the sides of the body of the juveniles is a number of large spots of the same color as the zigzag that become even larger with age. Coloration of the throat is light in all specimens. The belly is grey-spotted on a dark background in most specimens, while the specimen from Uanat (1935) has a dark-spotted belly on a light background and in the specimen from Atsriskhevi (No. 1086) the belly is black. The lower part of the tail in both sexes is pinkish with varying degrees of dots in males and without dots in females. The coloration of the supralabials varies from almost white to black with different specks or stripes, which can be located both at the top of the shields and in the form of dark stripes at the seams.

Etymology. The species is named after Boris Tuniyev, who made a significant contribution to the study of the Caucasian herpetofauna and the taxonomy of the shield-head viper snakes.

Geographical distribution and biotopes. All known finds are located in the left-bank basin of the middle flow of the Kura River from the Borzhom Gorge (east slope of Meskheti Ridge) in Ge to middle-mountain districts of SO (east foothills of Likhsky Ridge and south spurs of Central Caucasus). Known localities in Ge: vicinity of Tashiskari V. and Baniskhevi Gorge below Borzhomi; known localities in SO: Gufta V., vicinity of Kusret V. (=Kusreti V.), vicinity of Kotstykau V. (=Kverneti V.), vicinity of Uanat V. (=Vanati V.), vicinity of Otreu V. (=Otrevi V.), South-Ossetian Reserve – vicinity of ruins of Atsriskhevi V., vicinity of Artseu V. (=Artsevi V.), vicinity of Grom V. (=Gromi V.), vicinity of Kharisdzhin V. (=Tormaneuli V.), vicinity of Dodot V. (=Zemo-Dodoti V. – Kvemo-Dodoti V.), vicinity of Kalet V. (=Kaleti V.), vicinity of Ksuis V. (=Ksuisi V.), vicinity of Tbet V. (=Tbeti V.) ( Fig. 9 ).

It inhabits mid-altitude broad-leaved forests, Carpinus orientalis shibliak and post-forest glades in the range of elevations from 700-850 m in the Borzhom Gorge of Ge, 800 m (Kalet V.) in SO to more than 1300 m asl (near the ruins of Atsriskhevi V., South Ossetian Reserve) ( Fig. 10 ).

Morphological, ecological and biogeographic notes

Geographically, the new species is isolated from the Adzharo-Lazistan population of P. kaznakovi by the medium-high Meskheti (Adzharo-Imeretinsky) Ridge (highest point – Mt. Mepitskaro, 2850 m) and its continuation, a rather low Likhsky (Suramsky) Ridge (Mt. Lokhoni, 1926 m).

There is every reason to assume that the ancestral form had a common geographic range in the southwestern Transcaucasia, which disintegrated into two populations in the Pleistocene and further fragment- ed in the basin of the Kura River in the Holocene, after the expansion of the xerophylous biota upward along the valley of the Kura River. Evidence for the Holocene expansion of xerophilous representatives of herpetofauna can still be seen today, for instance, in a recent find of Dolichophis schmidii (Nikolsky 1909) in SO ( Tuniyev et al. 2017b). The valley of the Kura River, as a route of spreading of xerophylous herpetofauna, was considered by M.A. Bakradze (1977) based on the records of Testudo graeca L., 1758, Lacerta media (Lantz et Cyren, 1920) , Paralaudakia caucasia (Eichwald 1831) , Eirenis modestus Martin, 1838 , Hemorrhois ravergieri (Menetries 1832) , Telescopus fallax iberus Eichwald, 1831 in the Borzhom Gorge and upward. This conclusion is also supported by paleontological finds in Dmanisi and paleoclimatic reconstructions ( Blain et al. 2014), indicating the presence in the early Pleistocene of semi-desert and steppe landscapes changing into Mediterranean light forest.

Despite the Holocene expansion of the xerophilous biota, many Colchian representatives of flora and fauna have survived in the Borzhom Gorge. Including the find of M.A. Bakradze (1969) “ P. kaznakovi ” made it possible to distinguish a special Borzhom refugium of the Colchian biota ( Tuniyev 1990; 1997).

It is necessary to note the maximum size and a very bright color of P. kaznakovi from the Adzharo-Lazistan population ( Fig. 11 ), compared to the KT – Ab population and, in fact, P. tuniyevi sp. nov. For a rather long time, characters of vipers such as less developed polymorphism and the absence of melanists in the southwestern Tanscaucasia, based on differences in allozyms ( Nilson et al. 1995), were considered as characteristic for the northwestern cluster of the species range. We have also noted them for P. tuniyevi sp. nov. in SO too. In this regard, it is interesting to indicate the record of a melanistic female in the Kinthrish Reserve (941), which changes the prevailing concept and characterizes a single set of possible morphs in vipers in the canalization of evolutionary processes.

Differences are also noted in the structure of the hemipenis. P. tuniyevi sp. nov. has longitudinal rows of 2–3 large, identical sized and hook-shaped spikes replaced by a small number of small spikes in the distal part of the hemipenis ( Fig. 12A ). P. kaznakovi has longitudinal rows of 2–3 slightly curved large spikes, the longest of which occupy a proximal position, replaced in the distal part by a large number of small spikes, located in numerous rows and turned towards the furrow of the hemipenis ( Fig. 12B ). The hemipenis of P. dinniki is characterized by longitudinal rows of 2–3 large straight spikes, the largest of which are located in the medial part, and few small spikes ( Fig. 12C ).

In the Borzhom Gorge P. tuniyevi sp. nov. is sympatric, and in Tashiskari V. is syntopic with Vipera transcaucasiana Boulenger 1913 , what is a larger and more competitive viper. Not so numerous as the latter, P. tuniyevi sp. nov. is found in small forest glades, overgrown shrubs and on the edge of the gorge with stony outcrops in the Carpinus orientalis shiblyak and in the Querceto-Carpinetum forest with a single Picea orientalis ( Fig. 10A ). The species is absent at talus slopes and large-block areas of the gorge where it is completely replaced by V. transcaucasiana .

A different situation is observed in the southern macro-slope of the Central Caucasus in the contact zone with the Inner Cartlian Plain. Given the modern find of G.N. Iremashvili Pelias shemakhensis kakhetiensis Tuniyev, Iremashvili, Petrova et Kravchenko, 2018 in Gorijvari V. ( Fig. 13 ), there is vicariation of three species of shield-head vipers in various high-altitude ecological belts. P. shemakhensis kakhetiensis is found in the steppe biotopes of foothills along the valley of the Kura River. P. tuniyevi sp. nov. lives in the broad-leaved forest belt up to the lower boundary of the dark coniferous forests at the bottom of mid-altitude mountains, whereas the eastern form of P. dinniki is common in the subalpine mountain meadow belt.

It should be noted that the southern slope of the Great Caucasus in this area is very short and steep, almost without advanced ridges. Thus, ideal conditions were created for unhindered contacts in the condition of multiple movements of high-altitude belts in the Pleistocene and Holocene. P. tuniyevi sp. nov. could have repeatedly come into contact with two other species and formed hybrids. Apparently, the observed sharp zigzag wings and gray tones in some males of P. tuniyevi sp. nov. are the result of gene introgression as a consequence of the past hybridization, at least with eastern P. dinniki . This is also indicated by the fact that P. tuniyevi sp. nov. and eastern P. dinniki belong to the same cluster, while retaining some external characters bringing P. tuniyevi sp. nov. closer to P. kaznakovi , and is further supported by the results of the cluster analysis and for females also of the CDA analysis. As opposed to the observed morphological similarity of P. tuniyevi sp. nov. with P. kaznakovi and clear differences in ecology from P. dinniki , genetic distances ( Table 16) were significant between P. kaznakovi and P. tuniyevi

Note: * – holotype.

sp. nov. (4.7%), but minimal between eastern P. dinniki and P. tuniyevi sp. nov. (0.9%).

Currently, biotopes of P. tuniyevi sp. nov. are characterized by more xero-mesophilic traits and moderately warm mezo-climate than typical mesophilic biotopes of North-Colchian (KT – Ab) and, especially, Adzharo-Lazistanian P. kaznakovi , living in the humid subtropical climate.

The conflict between morphological and genetic analysis is known for many groups of reptiles and continues to be the subject of debate ( Pavlinov 2014; Tuniyev et al. 2014; Ananjeva 2019; Speybroeck et al. 2020). The categorical conclusions of a number of authors ( Gvozdik et al. 2012; Zinenko et al. 2015) based solely on the results of the genetic analysis are, in our opinion, a priori assumptions, especially in the case of well-developed geographical and hypsometric isolation, with objective differences in external morphology (size, coloration and color pattern, pholidosis). These features are unique for each species (subspecies) and associated with ecological characteristics of biotopes, geographic distribution and the history of speciation, with the accumulation of original features in each region of formation. It should be taken into account an essential role of hybrid speciation, which have probably occurred in vipers throughout the Caucasus ( Joger and Zinenko 2021). We confirm the need to implement integrative taxonomic approaches for the recognition of evidence-based taxonomic units in Eurasian vipers and further research to clarify taxonomic arrangements ( Freitas et al. 2020), which is important for the study and conservation of this important model group of the Caucasian Ecoregion.

Figures

Fig. 7. Holotype of Pelias tuniyevi sp. nov. (SNP No 937) (photo B.S. Tuniyev)

Fig. 8. Paratypes of Pelias tuniyevi sp. nov.: A – Uanat V. (1935) (photo B.S. Tuniyev); B – Atsriskhevi V. (1086) (photo V.V. Tikhonov); C – Kharisdzhin V. (1182) (photo B.S. Tuniyev); D – Kharisdzhin V. (951) (photo B.S. Tuniyev); E – Tashiskari V. (1140); F – Tashiskari V. (1054)

Fig. 9. Known localities of P. tuniyevi sp. nov: Ge: 1. Baniskhevi Gorge; 2. Vicinity of Tashiskari V.; SO: 3. Vicinity of Kalet V.; 4. Vicinity of Kharisdzhin V. (terra typica); 5. Vicinity of Dodot V.; 6. Vicinity of Kusret V.; 7. Vicinity of Gufta V.; 8. Vicinity of Ksuis V.; 9. Vicinity of Atsriskhevi V.; 10. Vicinity of Uanat V.; 11. Vicinity of Artseu V.; 12. Vicinity of Grom V.; 13. Vicinity of Tbet V.; 14. Vicinity of Otreu V.

Fig. 10. Habitats of P. tuniyevi sp. nov.: A – Carpinus orientalis shibliak with forest glades in vicinity of Tashiskhari V. (photo B.S.Tuniyev); B – Derivates of broad-leaf forests and post-forest glades in vicinity of Kharisdzhin V.(terra typica) (photo B.S. Tuniyev).

Fig. 11. Color patterns of P. kaznakovi from Adzharo-Lazistan population: A, B – vicinity of Arkhavi, Turkey (photo B. Heras); C – Mt. Mtirala, Adzharia (photo B.S. Tuniyev), Ge; D – Vicinity of Batumi, Adzharia, Ge (photo B. Heras); E, F – Kintrish Reserve, Adzharia, Ge (F – photo B.S. Tuniyev).

Fig. 12. Morphology of hemipenis (photo B.S. Tuniyev): A – P. tuniyevi sp. nov. (vicinity of Kharisdzhin Vil., SO, holotype), B– P. kaznakovi (Mt. Soutlyantepe, Sochi, Russia), C – P. dinniki (beginning of Malaya Laba River, Caucasian Reserve, Russia, topotype).

Fig. 13. Pelias shemakhensis kakhetiensis from vicinity of Goridjvari V., Ge