Hylomus piccolo, Nguyen & Vu & Nguyen, 2025

Nguyen, Anh D., Vu, Tam T. T. & Nguyen, Thu-Anh T., 2025, Mountainous millipedes in Vietnam. III. Two new dragon millipedes from limestone mountains in northern Vietnam (Polydesmida, Paradoxosomatidae, Hylomus), with an identification key to Vietnamese Hylomus species, ZooKeys 1223, pp. 247-262 : 247-262

publication ID	https://doi.org/ 10.3897/zookeys.1223.139649
publication LSID	lsid:zoobank.org:pub:586F1538-6192-4A99-A3D5-8B37DAECEE58
DOI	https://doi.org/10.5281/zenodo.14624241
persistent identifier	https://treatment.plazi.org/id/831524D8-E34E-5890-B862-2D92AB730445
treatment provided by	ZooKeys by Pensoft
scientific name	Hylomus piccolo
status	sp. nov.

Treatment

Hylomus piccolo sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Material examined.

Holotype. Vietnam • 1 male; Cao Bang Province, Pia Oac-Pia Den National Park ; 22.5943 ° N, 105.8846 ° E; 1200 m a. s. l.; 9 May 2021; Anh D. Nguyen leg.; bushes; IEBR-Myr 904 H GoogleMaps . Paratypes. Vietnam • 10 males, 5 females; same data as for holotype; EBR-Myr 904 P GoogleMaps • 1 male, 1 female; same data as for holotype; IEBR-Myr 901 GoogleMaps .

Diagnosis.

The species can be discriminated from the congeners by the presence of long spiniform paraterga, midbody metaterga with only two rows of 1 + 1 small setiferous spines in the middle and 2 + 2 longer setiferous spines near posterior margin; male femora 6 with a large tubercle ventrally; sternite 5 with a large, sparsely setose, bifid, trapeziform lamina between male coxae 4; epiproct without conspicuous setiferous knobs near tip; gonopod lamina lateralis broadly rounded, partly folded to sheathe distal part of solenomere; gonopod lamina medialis with a small rounded lobe at middle.

The new species is similar to Hylomus namek Nguyen et al., 2019 but differs from this species by the following characters: the ventral side of male femora 6 with a big, robust tubercle in the middle (vs. femora 6 and 7 with large tubercles); longer spiniform paraterga; and gonopod lamina medialis with a small rounded lobe in the middle (vs. without processes).

Etymology.

The name refers to “ piccolo ”, a main character of the Japanese manga “ Dragon balls ” by Toriyama Akira ( Japan). Noun in apposition.

Description.

Length c. 11.6–12.8 mm (male), 13.9–15.2 mm (female); width of midbody pro- and metazona (distance between two paratergal tips) 0.6–0.8 mm (male), 1.12–1.25 mm (female) and 3.1–3.3 mm (male), 3.4–3.6 mm (female), respectively. Holotype length c. 11.8 mm, width of midbody pro- and metazona 0.74 mm and 3.2 mm, respectively.

Coloration: Generally darkish-red to darkish-brown except paraterga, sterna, legs whitish-yellow; distal part of main branch pinkish.

Head (Fig. 1 A – C View Figure 1 ): Clypeolabral region densely setose, vertex sparsely setose. Epicranial suture distinct, dividing frons into two equal parts; with setae along the suture. Antenna slender, extremely long, reaching back to body ring 7 if stretched along the body axis; antennomere 1 <7 <6 <2 <3 = 4 = 5 in length.

Collum (Fig. 1 C View Figure 1 ): Slightly narrower than head; surface dull, coarsely microgranulate; with two rows of spines: 3 + 3 spines in anterior row and 2 + 2 spines in posterior row. Paraterga of collum well developed, spiniform; directed dorsad; highly elevated above dorsal surface; with two conspicuous teeth on anterior side.

Body rings: Ring 3 <4 <2 = 5–16 in width, thereafter gradually tapering towards telson. Prozona finely shagreened; metazona and pleura with microgranulations. Transverse sulcus present, but inconspicuous on metaterga 5–18. Axial line missing. Metaterga with two rows of 1 + 1 smaller setiferous spines in middle and 2 + 2 longer setiferous spines near posterior margin (Fig. 2 B View Figure 2 ). Suture between pro- and metazona broad, very shallow. Pleurosternal carinae present as a complete keel on body rings 2–3, then missing on subsequent body rings.

Paraterga (Figs 1 View Figure 1 , 2 View Figure 2 ): Very well developed; directed dorsad; long and spiniform with a large branch and 2–3 tiny teeth on anterior side (2 on poreless body rings and 3 on pore-bearing rings) and with 1 larger spine on posterior side. Paratergum on ring 19 directed caudad. Ozopore located between the second tooth and main branch of paraterga, visible in dorsal view.

Telson (Fig. 3 A, B View Figure 3 ): Epiproct without conspicuous setiferous knobs near tip, but broadly truncated; tip with four spinnerets; lateral tubercles well developed (Fig. 3 A View Figure 3 ). Hypoproct subtrapeziform, with two distolateral, completely separated, setiferous knobs (Fig. 3 B View Figure 3 ).

Legs: Extremely long, slender and thin, c. 1.8–2.0 times as long as midbody height. Prefemora not swollen. Male femora 6 each ventrally with a large, robust tubercle in middle (Figs 1 A View Figure 1 , 3 C View Figure 3 ).

Sterna: With distinct cross-impressions, no modification – except a large, sparsely setose, bifid, trapeziform lamina between male coxae 4 (Figs 1 A View Figure 1 , 3 D View Figure 3 ).

Gonopod (Fig. 4 View Figure 4 ): Suberect. Coxite (co) cylindrical, larger than femorite, sparsely setose distodorsally. Prefemorite (pref) densely setose, equal to femorite as well. Femorite (fe) slightly enlarged distad (from ventral view); without a demarcation with postfemoral region. Postfemoral region inconspicuous. Solenophore (sph) well developed; lamina lateralis (ll) broadly rounded, partly folded to sheathe distal part of solenomere; lamina medialis (lm) with a small rounded lobe at about midway. Seminal groove running entirely on mesal side, then entering a flagelliform solenomere (sl), solenomere partly sheathed by solenophore. Tip of solenophore rounded.

DNA barcoding.

(Appendix 1) A fragment of the COI gene is accessioned at NCBI GenBank with the following accession number PQ 676351. The new species exhibits a COI gene similarity of 86.22 % and 86.57 % (OR 765910 and MG 669370 View Materials , respectively) identity with Hylomus cervarius ( Attems, 1953) .