Propolyxenus argentifer ( Verhoeff, 1921 ) Short & Vahtera & Wesener & Golovatch, 2020

Short, Megan, Vahtera, Varpu, Wesener, Thomas & Golovatch, Sergei I., 2020, The millipede family Polyxenidae (Diplopoda, Polyxenida) in the faunas of the Crimean Peninsula and Caucasus, with notes on other European Polyxenidae, Zootaxa 4772 (2), pp. 306-332 : 313-320

Propolyxenus argentifer ( Verhoeff, 1921) new combination

Figs 2–4 ; Map Fig. 1

Polyxenus sokolowi (sic!, nomen nudum) — Sokolow, 1918: 1 (R).

Polyxenus argentifer Verhoeff, 1921: 47 (D).

Polyxenus ponticus (?) (sic!)— Brolemann, 1921: 160.

Polyxenus Sokolowi Lignau, 1924: 193 , 197 (D), syn. n.

Polyxenus sokolowi— Kobakhidze, 1965: 390 (L, R); Lokšina and Golovatch, 1979: 381 (L, R); Talikadze, 1984: 143 (L, R).

Polyxenus trivittatus Verhoeff, 1941a: 262 (D, R), syn. n.

Polyxenus trivittatus — Verhoeff, 1941b: 297 (D, R); 1943: 241 (L, R).

Polyxenus argentifer— Lohmander, 1936: 166, 178 (L); Lang, 1959: 1789 (L); Kobakhidze, 1965: 390 (L, R); Lokšina and Golovatch, 1979: 381 (L, R); Talikadze, 1984: 143 (L, R); Kokhia and Golovatch, 2018: 38 (L, R).

? Polyxenus sp.— Enghoff and Moravvej, 2005: 62 (L, R).

Propolyxenus trivittatus— Condé and Nguyen Duy, 1971: 1257 (L).

Propolyxenus aegeus / trivittatus (sic!)— Korobushkin et al., 2016: 20 (R).

Propolyxenus trivittatus (sic!)— Enghoff, 2006: 177 (L, R); Chumachenko, 2016: 408 (R).

Non Polyxenus ponticus— Nguyen Duy-Jacquemin and Geoffroy, 2003: 100 (D, L) (erroneously synonymized with P. argentifer Verhoeff, 1921 ).

Propolyxenus trivittatus— Short and Vahtera, 2017: 7 (L).

Remarks: Propolyxenus trivittatus Verhoeff, 1941 and Polyxenus Sokolowi Lignau, 1924 are here considered synonyms of Propolyxenus argentifer ( Verhoeff, 1921) .

Material examined: Numerous males, females and juveniles of various stadia + slides.

Lectotype (by present designation): adult male, whole mount on slide in Canada balsam, Azerbaijan, Lankaran, at the Caspian Sea , N38º45’, E48º51’, pre-1921, det. Verhoeff ( ZSM /Myr-20031629) . Paralectotypes (by present designation): determined by Verhoeff from the same location and time as lectotype and mounted in Canada bal-sam—male on two slides: anterior to 6 th tergite in 6 parts ( ZSM /Myr-20031622:); posterior in 7 parts ( ZSM /Myr- 20031623); 1 ex. in many parts ( ZSM /Myr-20031625); Croatia, Abbazia (Opatija), N45º20’, E14º18’, pre-1921, leg. Verhoeff, mounted on slides in Canada balsam: 1 ex. in 3 parts ( ZSM /Myr-20031624), 1 ex. sub-adult damaged ( ZSM /Myr-20031628), 1 ex. damaged ( ZSM /Myr-20031627); Romania, Herkulesbad , N44º52’, E22º24’, pre-1921, leg. Verhoeff, mounted on slides in Canada balsam: 1 ex. adult ( ZSM /Myr-20031621), 1 female adult ( ZSM /Myr- 20031626), poor condition. Topotypical material: 2 adult males ( VNR 018339-1 , VNR 018339-2 ) , 3 adult females ( VNR 018339-3 , VNR 018339-4 , VNR 018339-5 ) , slide mounts; 31 mixed stadia in EtOH ( VNR 018341-1 ) : Azerbaijan, Talysh Mts, Lerik Rayon, Hyrcan Nature Reserve, Piran , northwestern town exit, pasture with single trees, under logs, stones, leaves, N38°44’2”, E48°38’38”, 26.III.2015, leg. H. Reip, D. Antić and F. Walther, deposited in SMNG .

Other material: unless indicated, specimens listed are stored in 80% ethanol and form part of the collection from ZMUM. Only locality data from the Caucasus is given. Crimea, 13 ex.; damaged, Sokolinoe, Mt Sotira, part of Boiko Mtn Range, edge of Pyrus forest, 1100 m a.s.l., N44°30’, E34°0’, 3. V.2015, leg. O.L. Makarova. Azerbaijan, 1 ex.; Zakatali Nature Reserve, Zeltik, Belakan-chai River valley, 800 m a.s.l., N41°35’19”, E46°43’26”, 24. V.1981, leg. S. Golovatch and J. Martens; 10+ ex.; Nakhichevan Autonomous Republic, Ordubad District, 4 km S of Bilav, old sparse Salix and Paliurus forest along river, in litter and logs, 1200 m a.s.l., N39°12’40”, E45° 24’38”, 23.IV.1983, leg. S. Golovatch; 7 ex.; Mountainous Karabakh, Dashalty by Shusha, Quercus and Carpinus forest, litter, logs, under stones, 1100–1300 m a.s.l., N39°43’34”, E46°50’27”, 1. V.1983, leg. S. Golovatch; 3 ex.; Mountainous Karabakh, Askeran District, ca. 6 km WNW of Dashbulag, near Badara, Quercus , Carpinus etc. forest, 850–900 m a.s.l., N39°55’40”, E46°39’16”, 2. V.1983, leg. S. Golovatch; 5 ex.; Nabran, ca. 30 km N of Khachmas, Quercus and Carpinus forest, under bark, 0 m, N41°45’, E48°41’, 21–22.IV.1987, leg. S. Golovatch and K. Eskov; 5 ex.; Khachmas District, Nabran, under bark, 0 m, N41°45’, E48°41’, 21–22.IV.1987, leg. S. Golovatch; 28 ex.; 5 km N of Kutkashen, Fagus and Carpinus forest, litter and rotten wood, 1150–1200 m a.s.l., N41°01’, E47°53’, 2. V.1987, leg. S. Golovatch and K. Eskov; 33 ex.; Chilisa ca. 7 km N of Kelbadjar, Quercus , Carpinus , Acer etc. forest, under bark, 1450–1500 m a.s.l., N40°06’, E46°02’, 31. V.1987, leg. S. Golovatch and K. Eskov; 3 ex.; Lesser Istisu halfway between Kelbadjar and Istisu, Quercus and Acer scrub on slope, litter, N40°00’, E45°59’, 31. V.1987, 1550 m a.s.l., S. Golovatch and K. Eskov; 6 ex.; Nadirkhanly ca. 12 km NE of Kelbadjar, Fraxinus and Juglans stand, litter, 1200 m a.s.l., N40º08’, E46º09’, 1. VI.1987, leg. S. Golovatch and K. Eskov; 6 ex.; Drmbon (Heyvali), 30 km WSW of Mardakert, Quercus , Carpinus , Acer etc. forest, litter, 800–850 m a.s.l., N40°09’, E46°36’, 1– 2. VI.1987, S. Golovatch and K. Eskov; 4 ex. on 2 slides ( VNR 018340-1, VNR 018340-2); Goygol Rayon, N40°26’, E46°21’, 29.III.2015, leg. H. Reip, D. Antić and F. Walther ( SMNG). Armenia, 30 ex.; Ararat District, Khosrov Nature Reserve, Juniperus with Quercus and Crataegus , along river, litter and under stones, 1450–1550 m a.s.l., N40°2’4”, E44°55’6”, 19–20.IV.1983, leg. S. Golovatch; 3 ex.; same locality, forest on slope, 1200–1900 m a.s.l., N40°2’59”, E44°52’6”, 12. V.1984, leg. V. Januschev; 4 ex.; Legvaz (Lehvaz) village ca. 4 km NNW Meghri, Juglans and Quercus shrub with Paliurus and Rosa , litter and under stones, 1000 m a.s.l., N38°56’24”, E46°13’40”, 24–25.IV.1983, S. Golovatch; 1 ex.; Kafan, under bark of log, N39°12’10”, E46°24’37”, 27.IV.1983, S. Golovatch; 2 ex.; Kafan District, Shikahoh Nature Reserve, Nerkin And (Nerkin Hand), old Platanus stand along river, litter, in rotten log, under stones, N39°3’8”, E46°24’46”, 30.IV.1983, leg. S. Golovatch; 2 ex.; Meghri District, SSE of Lichk, Meghri River valley, Quercus wood, litter, under stones, in rotten wood, 1530 m a.s.l., N39°1’17,” E46°13’7”, 25.IV.1983, leg. S. Golovatch; 2 ex.; Dilizhan (Dilijan) Nature Reserve, Agartsyn, Fagus forest, litter, in logs, under stones, 1250–1300 m a.s.l., N40°47’10”, E44°54’54”, 17.IV.1983, leg. S. Golovatch; 11 ex.; Meghri District, 6 km N of Shvanidzor, sparse Quercus forest, litter, under stones and bark, 1200–1300 m a.s.l., N38°59’35”, E46°21’47”, 24.IV.1983, leg. S. Golovatch; 4 ex.; Idjevan (Ijevan) District, Tsaghkavan, Quercus , Acer , Carpinus etc. forest, litter and tree hole, 850–900 m a.s.l., N40°56’, E45°19’, 25. V.1987, leg. S. Golovatch and K. Eskov; 6 ex.; Gandakar, S of Idjevan, Quercus and Cordylus scrub, litter, 1000 m a.s.l., N40°50’, E45°09’, 28. V.1987, leg. S. Golovatch and K. Eskov. Georgia, 1 ex.; Thibani (Tibaani) near Tsnori, Alnus and Crataegus shrub, litter, N41°34’30”, E46°0’3”, 7. V.1983, leg, S. Golovatch; 12 ex.; Vashlovan(i) Nature Reserve, Juniperus and Pistacia sparse forest, 500–800 m a.s.l., N41°11’25”, E46°28’24”, 7–9. V.1983, leg. S. Golovatch; 2 ex.; Borzhomi (Borjomi) District, 8 km SE of Akhaldaba, Nedzura River valley, Picea , Carpinus and Fagus forest, litter, logs, 1000 m a.s.l., N41°52’49”, E43°31’23”, 12. V.1983, leg. S. Golovatch; 9 ex.; 15 km W of Adigeni, Abies , Picea , Fagus , Acer etc. forest, 1500– 1700 m a.s.l., N41°41’15”, E42°34’9”, 14–15. V.1983, leg. S. Golovatch; 1 ex.; Adzharia, Zelenyi Mys, Batumi Botanical Garden, 20–150 m a.s.l., N41°38’4”, E41°40’16”, 30.V–7. VI.1981, leg. S. Golovatch and J. Martens; 14 ex.; N of Kvareli, Fagus , Carpinus , Quercus etc, forest, litter and under bark, 700–750 m a.s.l., N41°58’ E45°48’, 4. V.1987, S. Golovatch and K. Eskov; 9 ex.; Babaneuri Nature Reserve, ca. 16 km NNW Akhmeta, nr Babaneuri, Carpinus , Quercus, Zelkova forest, dry litter, 500 m a.s.l., N42°5’, E45°22’, 4–5. V.1987, S. Golovatch and K. Eskov; 12 ex.; Batsaro Nature Reserve, ca. 20 km N of Akhmeta, Fagus , Castanea etc. forest litter, 800–850 m a.s.l., N41°45’, E48°41’, 5–6. V. 1987, leg. S. Golovatch and K. Eskov; 6 ex.; Magalakhari Pass, between Akhmeta and Tianeti, Fagus and Carpinus forest, litter and under bark, 1200 m a.s.l., N42º05’, E45º01’, 6. V.1987, leg. S. Golovatch and K. Eskov; 34 ex.; Mariamjvari Nature Reserve, NE of Sagarejo, Fagus , Carpinus , Acer , Pinus etc. forest, litter and under bark and stones, 1150–1250 m a.s.l., N41°45’, E45°23’, 13–14. V.1987, leg. S. Golovatch and K. Eskov; 5 ex.; Tbilisi, Tskhneti, Fagus , Carpinus , Acer etc. forest, litter, 1150–1300 m a.s.l., N41°51’, E44°48’, 16–18. V.1987, leg. S. Golovatch and K. Eskov; 4 ex.; Bolnisi District, Safarlo SSW of Patara Dmanisi, Quercus , Fagus , Acer etc. forest, litter, 1000–1050 m a.s.l., N41°51’, E43°23’, 21. V 1987, leg. S. Golovatch and K. Eskov. Russia, 1 ex. (missing); Krasnodar Province, Sochi, Krasnaya Polyana, alpine belt, moss, 1900 m a.s.l., N43°40’28”, E40°12’5”, 6. VII.1956, leg. M.S. Ghilarov; 1 ex.; same locality, Castanea wood, 500 m a.s.l., N43°40’28”, E40°12’5”, 30. VI.1956, leg. K. V. Arnoldi; 2 ex.; same locality, alpine belt, moss, 1900 m a.s.l., N43°40’28”, E40°12’5”, 4. VII.1956, leg. M.S. Ghilarov and K. V. Arnoldi; 1 ex.; same locality alpine belt, moss, 1900 m a.s.l., N43°40’28”, E40°12’5”, 4.VIII.1956, leg. M.S. Ghilarov; 1 ex.; same locality, Castanea wood, moss, 500 m on Cytisus , N43°40’28”, E40°12’5”, 16. V.1955, leg. K. V. Arnoldi; 1 ex.; Krasnodar Province, Canyon Djankhot (Dzhankhot), S of Gelenjik (Gelendzhik), Pinus , N44°28’13”, E38°9’54”, 5. VI.1956, leg. M.S. Ghilarov; 1 ex.; 8 km E of Gelenjik (Gelendzhik), forest, N44°33’43”, E38°10’, 49”, 25. V. 1956, leg. M.S. Ghilarov; 3 ex.; 4 km S of Gelenjik, Markotkh Mtn Range, 620 m a.s.l., N44°36’50”, E38°3’51”, 1. V.2016, leg. K. and O. Makarov; 4 ex.; W. outskirts of Gelenjik, lower course of Yashamba River, 20 m a.s.l., N44°35’30”, E37°59’3”, 2. V. 2016, leg. K. and O. Makarov. 1 ex.; Goryachy Klyuch, Pshaf Mtn Ridge, near Mt ‘Belaya latka’, Quercus forest, litter, N44°38’26”, E39°1’46”, 18. VI.1956, leg. M.S. Ghilarov; 2 ex.; same locality, near Mt ‘Belaya latka’, Quercus forest, N44°38’26”, E39°1’46”, 17. VI.1951, leg. M.S. Ghilarov; 2 ex. (1 slide); same locality, forest in canyon, north face, N44°38’24”, E39°7’57”, 8.IV.1952, leg. K. V. Arnoldi; 1 ex.; Goryachy Klyuch, pine litter, N44°38’24”, E39°7’57”, 7.IV.1952, leg. K. V. Arnoldi; 1 ex.; Goryachy Klyuch, Mt Besedka, N slope, N44°38’24”, E39°7’57”, 3.IV.1952, leg. K. V. Arnoldi; 1 ex.; Kuban, 8 km S of Azovka, forest litter, N45°3’50”, E38°53’2”, 12.X. 1950, leg. K. V. Arnoldi; 2 ex.; Kuban, Lvovskaya village, Aushed River, N44°59’39”, E38°37’50”, 11. VI.1956, leg. M.S. Ghilarov; 4 ex. (1 slide); same locality, N44°59’39”, E38°37’50”, 12. VI.1956, leg. M.S. Ghilarov; 1 ex.; Krasnodar Province, Ubinskaya village, Quercus forest NW face, N44°44’7”, E38°32’33”, 9. VI. 1956, leg. M.S. Ghilarov; 30 ex.; Utrish Nature Reserve, secondary growth on abandoned heliport, some shrubs with dominant Paliurus , N44°44’23”, E37°24’55”, 25. VI. 2013, leg. I. Tuf; 1 ex.; Stavropol Province, E of Novopavlovsk, Quercus , Salix , Alnus etc. forest along stream, N43°57’24 ’, E43°42’58”, 28. V.1982, leg. S. Golovatch; 7 ex.; Stavropol Province, Georgievsk, Safonovsky Forest, Podkumok River floodplain, under bark, N44°10’, E43°30’, 10. VII. 2013, leg. R. V. Zuev; 3 ex.; Stavropol, Botanical Gardens, Pinus plantations, under bark, N45°02’, E41° 54’, 26.III. 2014, leg. R. V. Zuev; 2 ex.; Stavropol Province, near Kislovodsk, Borgustansky Mt Ridge, Pinus plantation, under bark, N43°57’, E42°23’, 20. VII. 2013, leg. R. V. Zuev; 5 ex.; environs of Stavropol, Besputskaya Polyana, forest clearing, under logs and stones, N45°03’, E41°51’, 2.III.2014, leg. R. V. Zuev; 2 ex.; Stavropol Province, Shpakovsky District, near Grushovyi, 11 km SW of Stavropol, Volchyi Vorota, steppe, 586 m a.s.l., N45°0’49”, E41°48’24”, 23.III.2014, leg. R. V. Zuev; 1 ex.; Republic of Adygea, Lagonaki Plateau, near sightseeing platform at Kamennoe Moor, in mosses on boulders and trees (sifted), N44°3’42”, E40°1’16”, 3. VII.2014, leg. M. Potapov; 1 ex.; same locality, Pinus and Betula forest on stones, in lichens on pine-trees (sifted), N44°3’42”, E40°1’16”, 3. VII.2014, leg. M. Potapov; 2 ex.; Republic of Adygea, road between Maikop and Lagonaki, Khajokh Gorge, outskirts of Kamennomostskiy, on wet rocks, N44°17’46”, E40°11’01”, 5. VI.2013, leg. M. Potapov; 1 ex.; W of Maikop, Fagus and Quercus forest, litter, 300 m a.s.l., N44°36’, E39°33’, 8. VII.1986, leg. S. Golovatch (all ZMUM). Iran, 1 ex. ( VNR 018342-1); Mazandaran, Chalus, Kalardasht, slope S of Kord Mahalleh, stony slope with grass and some low shrubs, 1,210 m a.s.l., N36º30’55”, E51º09’31”, 21.IV.2017, leg. H. Reip, K. Voigtländer and D. Antić ( SMNG); 7 ex. ( VNR 018343-2); Gilan, Rezvanshahr, Gisum forest 4.5 km NW of Parehsar (along Rasht–Astara Rd) S of Kish Khaleh, lowland broadleaf forest ( Parrotia , Carpinus , Quercus , few Tilia ) Rubus understorey, under bark, 10 m a.s.l., N37º38’29”, E49º01’49”, 17.IV.2017, leg. H. Reip, K. Voigtländer and D. Antić ( SMNG); 13 ex. + bits ( VNR 018344-1); same location, 17.IV.2017, leg. D. Antić, H. Reip & K. Voigtländer ( SMNG); 1 ex. ( VNR 018345-1); Tehran, Firuzkuh, 1 km SW of Gaduk Pass, semi-desert, 2,170 m a.s.l., N35º49’49”, E52º55’9”, 23.IV.2017, leg. H. Reip, K. Voigtländer and D. Antić ( SMNG).

Rediagnosis: Six ommatidia each side of the head with adjacent trichobothria arranged at points of isosceles triangle with angles all acute. Internal trichobothrium smaller and immediately adjacent to lateral edge of the row of posterior vertex trichomes; pair of medial trichomes on vertex, posterior to posterior vertex rows. Tergites with trichomes arranged in rosettes laterally, with three or more transverse rows along posterior edge, anterior tergal trichomes barbate and directed anteriorly, while posterior rows of tergal trichomes larger, directed posteriorly and scale-shaped, covering the dorsal surface in live animals and reflecting light to give a silvery appearance (Golovatch pers. comm., 2017; Verhoeff 1921). Medial fan of more than 45 barbate trichomes dorsal to a caudal bundle comprising two distinct halves. Number of sensilla on 6 th antennal article typically three.

Redescription: Measurements. Body length without caudal bundle, lectotype (slide mounted) 3.3 mm; paralectotypes (all slide mounted) 3–3.4 mm (n=3); topotypical material, slide mounted: female, 3.5 mm, width 1.2 mm (n=3), male, 3.4 mm, width 1.0 mm (n=2); topotypical material in ethanol: female adults length, 3.4 mm, width 1.1 mm, caudal bundle 1.1 mm (n= 9), male adults 3.1 mm, width 1.0 mm, caudal bundle 0.9 mm (n=9); female subadult length 2.6, width 1.0 mm (n=2), immatures: stadium 6, length 2.2 width 0.8 mm (n=2); stadium 4, length 1.5 mm, width 0.6 mm (n=1), stadium 3, length 1.3 mm, width 0.5 mm (n=1), stadium 2 length 0.9 mm, width 0.5 mm (n=2).

Head ( Fig. 3 ): six ommatidia on each side, of which one antero-ventral. Vertex with one pair of posterior tufts of 25+27 (lectotype) and 28–30 (adult females n= 4), 23–25 (adult males n=2) trichomes each side in topotypes, consisting of two uneven rows ( Fig. 3A ); the distance between each tuft is about half their length. Small gap only to anterior vertex trichome insertions. Pair of trichomes medial on vertex, posterior to posterior vertex trichome rows, vertex trichomes barbate. Three trichobothria on each side arranged in an isosceles triangle, with the most internal (immediately adjacent to lateral end posterior rows of vertex trichomes) smaller than the two others ( Fig. 3A ). Each with slightly thicker cylindrical funicle. Surface of labrum ( Fig. 4C ) with numerous small short cuspidate papillae; anterior two to three rows with larger papillae; 4–5 lamellate plates either side of median cleft on anterior margin ( Fig. 4C ), clypeo-labrum with 9–11 setae along posterior margin ( Fig. 4C ); lateral palp of gnathochilarium with 13–18 long sensilla, medial palp with 13–17 sensilla ( Fig. 3G , 4H ), sensilla of lateral palp all tall cylindrical, medial palp with 5–8 of same sized sensilla as lateral palp, remaining sensilla smaller and biarticulate, lateral palp varies in size from 2.5–3.5 times length of the medial palp. Antennae: proportions of antennal articles as in Fig. 3H . Details of sensilla based on topotypes. Antennal article VI with three basiconic sensilla: anterior thin and two posterior thick, one setiform sensillum between anterior and posterior ones, and one posterior coeloconic sensillum ( Figs 3K , 4G ); antennal article VII with two thick basiconic sensilla to posterior of four thin basiconic sensilla arranged in an arc curving distally (occasionally three or five in other material), one setifom sensillum between the two posterior basiconic sensilla and one posterior coeloconic sensillum ( Figs 3I, J , 4G ).

Trunk: collum with almost symmetrical arrangement of trichomes with lateral dense patches of barbate trichomes arranged in 3–4 diagonal rows with scattered trichomes internally towards the mid-line. Barbate trichomes forming a single continuous row anteriorly with an uneven double row of scale-like trichomes posteriorly ( Figs 3B , 4A ). Scattered trichomes medial to lateral patches either side. Lateral protuberances of collum with 4–7 barbate trichomes (lectotype 5(L)+6(R), topotypes 4–6). Remaining tergites (except for tergite 10) with 3–5 uneven rows of trichomes along the posterior edge of the tergite with rosettes of trichomes laterally. Rosettes with 3–5 diagonal rows of trichomes. Tergites 2–9 with 3–5 transverse rows of trichomes along the posterior edge with the most anterior being very short barbate trichomes facing anteriorly, with slightly longer ones in the next row, sometimes alternating with the anterior row to give the appearance of just one uneven row. The trichomes of the posterior rows are mostly in two uneven rows, directed caudally, and scale-like in appearance, wider than the barbate trichomes and longer than trichomes of the more anterior rows. The scale-like trichomes overlap each other and cover most of the subsequent tergite. ( Figs 3 C–E, 4B, D). Tergite 10 with 1–3 uneven rows of trichomes only, with most posterior row with smaller insertions, medially a single row, 2–4 diagonal rows of trichomes forming a flattened cluster laterally either side ( Fig. 3E , 4J ). The trichomes of the pleural processes are longer and arranged in a dense bunch of 40–70+ trichomes. Legs ( Figs 3L , 4E ): naming of leg segments is after Manton (1956). Legs 1 and 2 without trochanter, leg 1 also lacks tarsus 1. Trochanter, post-femur and tarsus 1 lack setae. Coxae I with one seta and coxae II with three setae; all other coxae without seta. Prefemora and femora with one seta; these large biarticulate setae having an elongate cylindrical funicle furnished with a long filiform process at apex, single tiny elongate seta on distal edge of each tibia ( Fig. 4E ). Tarsus II spine ( Fig. 4E ) longer than telotarsus: length of spine to claw ratio about 1.4:1. Telotarsus ( Fig. 4I ) bears an anterior process with a spinous projection longer than claw, a single large latero–posterior process associated with the claw, and a posterior lamellar process longer than the claw.

Telson: Medial cluster of 70+ medial (ornamental) trichomes with insertion points forming a ventrally pointing triangular shape, dorsal to the caudal trichomes ( Fig. 3F , 4J ). Ornamental trichomes darkly pigmented, both short and long barbate, forming a fan-like shape typical of the subfamily Polyxeninae ( Condé and Nguyen Duy-Jacquemin 2008) . Longest barbate trichomes equal to length of longest barbate trichomes of the caudal bundle. The caudal bundle of both hooked trichomes and long barbate trichomes, typical of the subfamily Polyxeninae with the caudal bundle in 2 halves with a wide gap medially. ( Figs 3F , 4J ). Hooked trichomes with three or four hooks arranged apically with a xiphoid process present and distally facing barbs along the stem of the trichome. ( Figs 3M , 4F ).

Sex differences: Males were found to be smaller than females. The smaller size of males was also reflected in smaller numbers of post vertex and tergal trichomes, and a smaller, narrower caudal bundle. Males tended to be in lesser numbers also and often found at the subadult stadium (VII). Other characters such as antennal sensilla did not vary between the sexes. Males had coxal glands on leg pairs 8 and 9.

Remarks: Verhoeff described the species Polyxenus argentifer from specimens collected over a wide area spanning Abbazia, Croatia; Herkulesbad, Romania; and Lankaran, Azerbaijan. It is therefore possible that the syntype series could represent different cryptic species. A lectotype was chosen from Lankaran, Azerbaijan as we had fresh material from the same location, as well as material that could be used for molecular genetic study. The remaining specimens in the syntype series have been designated as paralectotypes.

This study confirms the widespread distribution of P. argentifer throughout southern Russia, through the Caucasian region and Iran. It is therefore possible that the distribution of this species includes Turkey, which is the type locality of Propolyxenus trivittatus that Verhoeff described 20 years later (Verhoeff 1941). In determining if it was the same or a different species to P. argentifer , he would have compared rather poor, thick slides with freshly collected material. The differences he described between the two included the length of the dorso-medial fan of ‘ornamental’ trichomes, the length of anterior vertex trichomes as measured by how much of the antennae they covered. These two characters lack reliability due to damage and loss of trichomes after collection and the variable positioning of antennae in slide mounts making the relative length of anterior vertex trichomes quite subjective. Verhoeff also said that the arrangement of trichomes on the collum differed between P. argentifer and P. trivittatus , however on re-examination, the types of P. argentifer have the same arrangement that he described for P. trivittatus . Verhoeff’s description of P. trivitattus is very brief and superficial. Condé and Nguyen Duy-Jacquemin (1970) identified P. trivittatus from Israel, and reported that, due to the condition and thickness of the slides of four syntypes mounted in Canada balsam, a re-examination was unable to provide further diagnostic characters. Further collections from Greece have been tentatively identified as P. trivittatus by Strasser (1967) and Nguyen Duy-Jacquemin (pers. comm., 2008). It appears that at no stage were the specimens from Israel and Greece compared with the types of Polyxenus argentifer . In the absence of any morphological differentiation, we synonymise Propolyxenus trivittatus and Polyxenus argentifer as Propolyxenus argentifer ( Verhoeff 1921) .

After considering all available information on Polyxenus sokolowi , we now consider it to be a junior synonym of Propolyxenus argentifer . The Polyxenus sokolowi types are presumed to have been destroyed in World War II so the description by Lignau (1924) must be relied on. The collection of the St. Petersburg Museum, Russia still contains an empty vial labeled “ Polyxenus sokolowi Lignau ”. The characters described by Lignau (1924) for P. sokolowi match those of P. argentifer with one exception, the number of ommatidia. Lignau described just five ommatidia on each side, whilst P. argentifer has six. However, Polyxenus / Propolyxenus species with just five ommatidia all still retain the separately placed antero-ventral ommatidium ( Ishii 1983, 1990; Short and Huynh 2010). Lignau’s drawing of the eye plate (1924, Fig. 12) showed the identical pattern of ommatidia for a polyxenid with six ommatidia, but without the antero-ventral 6 th ommatidium. A likely explanation is that the often difficult to view antero-ventral 6 th ommatidium was overlooked. Although no collections have been made at the site of collection of P. sokolowi , numerous Propolyxenus argentifer have been found in similar locations on the edge of the Black Sea to the north and south.

It appears to have been an oversight that Polyxenus argentifer Verhoeff, 1921 was never reassigned to the genus Propolyxenus despite having three or more rows of tergal trichomes and other characters in common with species in the genus Propolyxenus . More specimens of P. argentifer need to be collected for examination for morphological differences, and more genetic analysis should be carried out on specimens collected over the very large range of the species. The large genetic distances observed between P. argentifer sensu stricto from the Caucasus and the more European populations of the species may be an indication of the existence of cryptic species.

Figures

FIGURE 1. Map to show localities of all specimens identified in this study. Map created using SimpleMappr, http://www.simplemappr.net, (Shorthouse 2010). Legend: Stars = Propolyxenus argentifer (Verhoeff, 1921) comb. n.; purple star = Verhoeff types; red star = identified in this study; orange = formerly identified as P. trivittatus (Verhoeff, 1921); green inverted triangle = Polyxenus lagurus (Linnaeus, 1758); green circle = Polyxenus lankaranensis sp. n.; white circle = Polyxenus sp.; yellow star = Propolyxenus aegeus Silvestri, 1948.

FIGURE 2. Propolyxenus argentifer (Verhoeff, 1921). comb. n., sub-adult male, Krasnodar Province, Russia; A. dorsal view, B. ventral view. Whole mount in 80% ethanol. Scale bar = 1 mm.

FIGURE 3. A–M, except J: Propolyxenus argentifer (Verhoeff, 1921) comb. n. Topotype, adult male. A. Head; B. Collum; Tergites showing pattern of trichome insertions: C. Tergite 2, D. Tergite 4; E. Tergite 10; F. Pattern of insertions of dorso-medial fan of trichomes on telson; G. right gnathochilarium; H. Left antenna showing proportions of articles; I. Article VII sensilla; K. Article VI sensilla; L. leg 8; M. Hooked caudal trichome. J. P. argentifer adult male, Russia, Utrish Nature Reserve, Article VII sensilla. Scale bars: A–E = 200 µm; F, G, M = 50 µm; I, J, K = 10 µm; H, L = 100 µm.

FIGURE 4. Scanning electron microscope (SEM) images of Propolyxenus argentifer (Verhoeff, 1921) comb. n. adult female: A. Dorsal view of head; B. Trichomes on tergite 2. C. labrum; D. Scale-like trichomes on tergites 8, 9 and 10; E. Portion of 8th leg showing setae: biarticular setae on prefemur (a) and femur (b) small setiform seta on tibia (c), spine on tarsus 2 (d); F. Hooked caudal trichome; G. Distal section of right antenna showing sensilla on articles 6, 7 and 8: thick basiconic sensilla (T), thin basiconic sensilla (t), conical sensilla (c), setiform sensilla (s); H. Lateral palp of gnathochilarium; I. Telotarsus showing claw (c) with posterior process (p), anterior spinous process (s). and lamella (l); J. telson showing pattern of insertions of ornamental trichomes. Scale bars: A, D, J = 200 µm; B, C, E = 50 µm; E, F, G, H = 20 µm; I = 10 µm.