Polyxenus lagurus (Linnaeus, 1758)

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 : 320-322

Polyxenus lagurus (Linnaeus, 1758)

Fig. 5 , Map Fig. 1 .

Polyxenus lagurus — Attems, 1904: 46 (R); Verhoeff, 1943: 241 (L, R); Golovatch, 1990: 362 (L, R), 2008: 108 (L, R); Chornyi

and Golovatch, 1993: 33 (R, D); Golovatch et al., 2017: 110 (L, R); Kokhia and Golovatch, 2018: 38 (L, R). Polyxenus Lagurus (sic!)— Lignau, 1905: 198 (L). Polyxenus lagurus var. caucasicus Lignau, 1924: 191 , 197 (D), syn. n. Polyxenus lagurus, var. caucasica (sic!, nomen nudum) — Sokolow, 1918: 1 (R). Polyxenus lagurus caucasicus— Lohmander, 1936: 166, 178 (L) (referred to as a subspecies); Kobakhidze, 1965: 390 (L, R);

Lokšina and Golovatch, 1979: 381 (L, R); Talikadze, 1984: 143 (L, R). Polyxenus lagurus lagurus— Lokšina and Golovatch, 1979: 381 (L, R);

Material examined: Crimea, 1 adult male, Bakhchisaray District, Mangup Plateau , under stones, ~ 500 m a.s.l., N44°35’38”, E33°47’42”, 8. V .2017, leg. K. and O. Makarov ( ZMUM) .

Russia, 1 imm. stadium IV (6 pl), Krasnodar Province, Anapa District, nr. Bolshoy Utrish, Abrau Peninsula , under stones, N44°45’34”, E37°23’23”, 26.III.2001, leg. I. Semenyuk ( ZMUM) . 3 imm. (stadia I, V and VI), Krasnodar Province, on road 2 km N of Dagomys, Quercus forest, litter, Berlese extraction, N43°40’11”, E39°37’18”, 2.VI.2013, leg. M. Potapov ( ZMUM) .

Rediagnosis: Similar to Propolyxenus argentifer in most characters but distinguished by the arrangement and shape of tergal trichomes which are arranged in two evenly spaced transverse rows of barbate trichomes with small rosettes laterally ( Fig. 5E ). Dorso-medial fan of barbate trichomes numbering fewer than 38 in total, in two distinct halves with medial gap. Number of thin basiconic sensilla on 6 th antennal article in adults always greater than three ( Fig. 5B ).

Remarks: Polyxenus lagurus has previously been identified from the Crimea ( Attems 1904) and from Gagra, Abkhazia (Issev 1911a), so it is not surprising to have identified it from the Crimean and Caucasian regions in this study. However, it is surprising that so few specimens were found. Polyxenus lagurus is the most widespread species of the Polyxenida having been identified throughout Europe including Great Britain, and Scandinavia and east to Israel ( Kime & Enghoff 2011). It has also spread to North America ( Condé 1996) and even to Australia ( Short and Vahtera 2017). There are both bisexual and parthenogenetic populations ( Enghoff 1978). The Crimean population is bisexual with the single specimen collected being male.

Lignau (1924) suggested that the specimens found at Gagra, Abkhazia were distinct from those from Europe and indicated this with the name P. lagurus var. caucasicus . Differences in size and shapes of trichomes are given as the argument for distinctness from European P. lagurus , based on comparison with figures in Humbert (1893) and Reincke (1910). However, because no magnification values or scale bar were available for the author’s figures, it is hard to ascertain the validity of the argument about size differences. The characters described for P. lagurus var. caucasicus differ little to those from the P. lagurus from Crimea in this study, so there seems insufficient evidence for maintaining a variety or subspecies status for the specimens described by Lignau. The one difference in Lignau’s description was that the medial posterior tergal trichomes had rows of 18–20 serrations along their length in contrast to 11–13 in P. lagurus from Crimea and elsewhere ( Brolemann 1935). COI sequencing (together with measurements on a photograph) of a Polyxenus specimen from Crimea suggests the presence of a second smaller Polyxenus species in Crimea.

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 5. Scanning electron micrographs of Polyxenus lagurus (Linnaeus, 1758), stadium VI (immature), Krasnodar Province, Russia, A. Dorsal view; B. Distal section of left antennal showing pattern of sensilla on article VI and VII; C. Left side of head showing ommatidia and trichobothria; D. Collum; E. Portion of 4th tergite showing pattern of trichome insertions. Scale bars: A = 500 µm; B. = 20 µm; C, D and E = 100 µm.