Polydesmidae, Leach, 1815

Golovatch, Sergei, Evsyukov, Aleksandr & Reip, Hans, 2016, The millipede family Polydesmidae in the Caucasus (Diplopoda: Polydesmida), Zootaxa 4085 (1), pp. 1-51 : 47-48

Key to Polydesmidae species presently known to occur in the Caucasus

1. Adults with 20 segments, including telson. Collum often as broad as or broader than head. Gonopod telopodite often elongate and subgeniculate distally.................................................................... Polydesmus, 2

- Adults with 19 segments, including telson. Head broader than collum. Gonopod telopodite stout and never subgeniculate distally................................................................................... Brachydesmus , 5

2. Live coloration usually light brown to brown ( Figs 3A, 5A). Paraterga not upturned, subhorizontal to slightly declivous, dorsum slightly, but clearly convex in the middle ( Figs 3A, 3H – 3J, 5A). Collum clearly narrower than head ( Figs 3A, 3H, 5A)...................................................................................................... 3

- Coloration largely red to pinkish. Paraterga very broad, held high, about level to a flat mid-dorsal region, a few first postcollum paraterga slightly, but clearly upturned ( Figs 2E, 3B)........................................................ 4

3. Male prefemora strongly bulging laterad ( Fig. 5B). Gonopod telopodite stout ( Fig. 5C)......... Polydesmus mediterraneus

- Male prefemora only slightly bulging laterad. Gonopod telopodite strongly elongate, subgeniculate distally ( Fig. 4C, 4D)............................................................................................ P. muralewiczi

4. Length ca 10 – 13 mm (male, female), width of midbody metazonae 1.25 – 1.7 (male) or 1.4 – 2.1 mm (female), metazonite to prozonite width ratio <2.0 ( Fig. 2). Collum about as broad as head ( Fig. 2A, 2B, 2F)......................... P. lignaui

- Length ca 13 – 19 mm (male, female), width of midbody metazonae 1.9 – 3.3 (male) or 2.4 – 3.5 mm (female), metazonite to prozonite width ratio> 2.0 ( Fig. 1). Collum clearly broader than head ( Fig. 1).............................. P. abchasius

5. Paraterga poorly-developed, their fore margins and anterolateral corners largely broadly and regularly rounded, not angular ( Fig. 10C). Metatergal sculpture strongly obliterate ( Fig. 10A – 10D). Gonopod exomere ( ex) with a conspicuous densely pilose strip ( Fig. 10E – 10G)................................................................ Brachydesmus furcatus

- Paraterga variously developed, but their fore margins and anterolateral corners mostly clearly angulate (e.g. Figs 6, 9A, 12, 13B, 13E, 15B, 16B, 16E). Metatergal sculpture often more strongly developed. Gonopod exomere without a pilose strip, but endomere often with densely pilose patches................................................................ 6

6. Tergal setae sharp ( Fig. 9A). Gonopod ( Fig. 9B) unipartite, slender, only slightly falcate, ventrally with several teeth or spines............................................................................................. B. superus

- Tergal setae mostly bacilliform or subclavate, only rarely sharpened. Gonopod telopodite bipartite, with a distinct exomere and a smaller, but evident endomere.

7. Adults < 8 mm long and ≤ 1.0 mm wide. Gonopod exomere with only a single apical tooth ( Figs 28C – 28D, 29C – 29G). Colchis, Black Sea coast area............................................................................ 8

- Adults ≥ 9 mm long and ≥ 1.0 mm wide.................................................................... 9

8. Length 6 – 7.5 mm, width of midbody metazonae 0.8 – 1.0 mm, metazonite to prozonite width ratio ca 1.5 – 1.6 ( Fig. 29A). Male legs slightly, but clearly incrassate ( Fig. 29B). Gonopod exomere longer ( Figs 29C – 29G). Ajaria, Georgia.. B. simplex sp. n.

- Length 5 – 6 mm, width of midbody metazonae 0.65 – 0.7 mm, metazonite to prozonite width ratio ca 1.3 ( Fig. 28A). Male legs slender ( Fig. 28B). Gonopod exomere shorter ( Figs 28C – 28D). Abkhazia and Sochi , Krasnodar Prov., Russia................................................................................................... B. kvavadzei sp. n.

9. Gonopod endomere ( en) partially densely pilose and clearly bifid; exomere ( ex) with 1 – 2 apical teeth e and i (the latter often subapical), often also with another subapical lobule or denticle l ( Figs 13G – 13H, 14C – 14E, 16G – 16H, 18D – 18E, 19D – 19E, 21D – 21F, 22 – 25, 27B, 27D). Extremely widespread (Map 2) and variable in all other characters, morphism outlined in Table 1...................................................................................... B. kalischewskyi

- Gonopods subfalcate, endomere ( en) simple, more or less finger-shaped ( Figs 7, 8E – 8F)........................... 10

10. Tergal setae mostly subclavate ( Fig. 6C – 6H). Gonopod exomere ( ex) more elaborate ( Fig. 7). Much of both Caucasus Major and Caucasus Minor, but not Hyrcania (Map 3)..................................................... B. assimilis

- Tergal setae sharp ( Fig. 9A). Gonopod exomere ( ex) simple ( Fig. 8F). Hyrcania (Map 3)................... B. pigmentatus