Polydesmus vietnamicus Nguyen, 2009

Nguyen, Anh D., Vu, Tam T. T. & Eguchi, Katsuyuki, 2024, The millipede family Polydesmidae Leach, 1816 (Diplopoda, Polydesmida) from Vietnam, with a description of a new cavernicolous species, ZooKeys 1190, pp. 259-280 : 259

Polydesmus vietnamicus Nguyen, 2009

Figs 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8

Materials examined.

Vietnam - Vinh Phuc Province • 1 ♂, 1 ♀ ; Vinh Phuc Province, Tam Dao National Park , near town; 1,000 m a.s.l.; 1 March 2005; Anh D. Nguyen leg.; natural secondary forest • 1 ♂ ; Vinh Phuc Province, Tam Dao National Park, on the way to Thac Bac waterfall; 1,000 m a.s.l.; 22 March 2005; Anh D. Nguyen leg.; bamboo forest, near stream • 1 ♂, 3 ♀ s, 1 juvenile; Vinh Phuc Province, Tam Dao National Park , around the town; 900-1,000 m a.s.l.; 15-18 October 2010; Anh D. Nguyen leg.; mixed forest; IEBR-Myr 967 • 3 ♀♀ ; Tam Dao National Park, on way to Tam Dao 2; 1,100 m a.s.l.; 25 February 2017; Anh D. Nguyen leg.; natural forest; IEBR-Myr 604 - Ha Giang Province • 2 ♂♂, 1 ♀ ; Bac Me Natural Reserve, Lac Nong commune, Ban Khen ; 22°45'30.8"N, 105°14'04.5"E; 11 December 2019; Anh D. Nguyen leg.; regenerated forest; IEBR-Myr 808 .

Diagnosis.

A typical polydesmid with 20 body rings and three transverse rows of bosses with setae on metaterga. Gonopodal solenomere rather well developed, conspicuously shaped. Endomere elongate and strongly falcate, directed caudally, starting laterally and basally of recurvature point of seminal groove, set off from femorite by a sulcus, with a pair of strong teeth at about midway (mt). Seminal groove largely mesal, crossing the femorite diagonally, terminal lateral loop relatively short and turning around a distofemoral process (ap). Solenomere (sl) short, but evident and bifid.

The species differs from the morphologically particularly similar Polydesmus liber Golovatch, 1991 in being larger (33.0-38.4 mm vs 21.0-23.0 mm in length) and in the gonopod endomere (with a pair of teeth at about its midlength vs with two pairs of moderate teeth at 1/3 and 2/3 of its length).

It is particularly noteworthy that all East and Southeast Asian species undoubtedly belonging to Polydesmus , however few, share the symplesiomorphy of densely setose gonopod coxites, which contrasts with very poorly setose ones observed in the much more numerous western Palaearctic counterparts ( Golovatch 1991).

DNA barcode.

The COI fragment (660 bp) was uploaded to GenBank with accession numbers PP118038 and PP118039. Polydesmus vietnamicus has a close COI identity to Pseudopolydesmus pinetorum (Bollman, 1888) (MT739870) and Pseudopolydesmus serratus (Say, 1821) (MT739862), with 89.8% (query coverage 83%) and 88.71% (query coverage 83%), respectively.

Remarks.

This species was previously known from only its type locality, Tam Dao National Park ( Nguyen 2009). Currently, its distribution is extended northward to Ha Giang Province. There are no significant morphological variations between the type specimens and those samples collected in Ha Giang.

Figures

Figure 1. Records of polydesmid species in Vietnam and of all known Pacidesmus species.

Figure 2. Polydesmus vietnamicus Nguyen, 2009 from Ha Giang Province (IEBR-Myr 808) A-C ♂. Anterior part of body A dorsal view B lateral view C ventral view D ♀, anterior part of body, ventral view. Scale bars: 1 mm.

Figure 3. Polydesmus vietnamicus Nguyen, 2009 from Ha Giang Province (IEBR-Myr 808) ♂ A midbody segment 8 - 11, dorsal view B posterior part of body, dorsal view C posterior part of body, lateral view D posterior part of body, ventral view. Scale bars: 1 mm.

Figure 4. Polydesmus vietnamicus Nguyen, 2009 from Ha Giang Province (IEBR-Myr 808) ♂ and ♀ under the UV light A ♂, anterior part of body, dorsal view B ♂, anterior part of body, ventral view C ♀, anterior part of body, ventral view D ♂, midbody segment 8 - 10, dorsal view. Scale bars: 1 mm.

Figure 5. Polydesmus vietnamicus Nguyen, 2009 from Ha Giang Province (IEBR-Myr 808) ♂, under the UV light A posterior part of body, dorsal view B posterior part of body, ventral view C telson, dorsal view D telson, ventral view. Scale bars: 1 mm.

Figure 6. Polydesmus vietnamicus Nguyen, 2009 from Ha Giang Province (IEBR-Myr 808) ♂, segment 7 with gonopods under the normal (A, B) and UV (C, D) light A, C posterior views B, D anterior views. Scale bars: 1 mm.

Figure 7. Polydesmus vietnamicus Nguyen, 2009 from Ha Giang Province (IEBR-Myr 808) ♂, right gonopod under the UV light A ventral view B lateral view C dorsal view D mesal view. Scale bars: 1 mm.

Figure 8. Polydesmus vietnamicus Nguyen, 2009 from Ha Giang Province (IEBR-Myr 808) ♂, right gonopod A mesal view B lateral view. Abbreviations: co = coxite; pref = prefemorite; ca = cannula; en = endomere; sl = solenomere; mt = midway teeth; ap = additional process. Scale bars: 0.5 mm.