taxonID	type	description	language	source
3B05C4F631AD50F7B51A9B5596DE560E.taxon	description	Figs 5, 6, 7	en	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: 247-262, DOI: 10.3897/zookeys.1223.139649
3B05C4F631AD50F7B51A9B5596DE560E.taxon	diagnosis	Diagnosis. The species can be discriminated from the congeners by the presence of spiniform paraterga; metaterga densely covered with microgranulations; midbody metaterga with two rows of setiferous spines: 2 + 2 in anterior row and 2 + 2 near posterior margin, the anterior row hardly seen, the posterior row more distinct; male femora 6 each with a large tubercle ventrally; sternite 5 with a large, sparsely setose, bifid, trapeziform lamina between male coxae 4; epiproct with several evident setiferous knobs near tip; gonopod solenophore partly folded to sheathe distal part of solenomere; tip of solenophore consisting of seven overlapping laminae. The new species is similar to H. proximus in body size and shape, but the two species are distinguished by the number of metatergal posterior spines (2 + 2 vs 3 + 3), male femoral modifications (femur 6 vs femora 5 & 6), and gonopod conformation. The new species has a well-developed gonopod solenophore (sph); a broadly rounded lamina medialis, partly folded to sheathe distal part of solenomere; and gonopod tip consisting of seven overlapping laminae while H. proximus has a gonopod femorite that is subequal to the postfemoral region in length; both solenophore and solenomere long; and a serrated solenophore tip. Hylomus borealis sp. nov. is also similar to H. jeekeli (Golovatch & Enghoff, 1994) from northern Thailand in terms of general body and gonopod shape. However, the new species can be distinguished from it by the combination of these characters: smaller in size with 10.4 mm in males and 12.3 – 13.4 mm in females (vs 15 – 16 mm in males and 18 – 20 mm in females); metaterga with 2 + 2 spines in posterior rows (vs 3 + 3 spines); modification in only femur 6 (vs femora 6 and 7); tip of solenophore consisting of seven overlapping laminae and not serrate (vs serrated solenophore).	en	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: 247-262, DOI: 10.3897/zookeys.1223.139649
3B05C4F631AD50F7B51A9B5596DE560E.taxon	etymology	Etymology. An adjective epithet “ borealis ” refers to the northern-most province (Cao Bang) of Vietnam, the type locality.	en	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: 247-262, DOI: 10.3897/zookeys.1223.139649
3B05C4F631AD50F7B51A9B5596DE560E.taxon	description	Description. Holotype length 10.4 mm, width of mid pro- and metazona 0.6 mm and 1.8 mm (distance between two paratergal tips), respectively. Female length 12.3 – 13.4 mm, width of mid pro- and metazona 0.9 – 1.0 mm and 1.7 – 1.8 mm, respectively. Coloration: Generally dark to castaneous brown except paratergal bases, sterna, leg coxae and prefemora whitish-yellow. Head (Fig. 5 A, B): Clypeolabral region densely setose, vertex sparsely setose. Epicranial suture distinct, dividing frons into two equal parts; with setae along suture. Antenna slender, extremely long, reaching to body ring 5 if stretched along the body axis; antennomere 1 <7 <6 <2 <3 = 4 = 5 in length. Collum (Fig. 5 B): Subequal to head in width; surface dull, coarsely and densely microgranulate, with three rows of spines: 3 + 3 spines in anterior row, 1 + 1 spines in intermediate row, and 2 + 2 spines in posterior row; all spines equal in size. Paratergum well developed; directed dorsad; highly elevated above dorsal surface; with two conspicuous teeth on anterior side. Body rings: Rings 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 setiferous spines: 2 + 2 spines in anterior row and 2 + 2 spines near posterior margin (Figs 5 C, 6 B), the anterior row hardly visible, the posterior row more distinct (Fig. 6 B). 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 (Fig. 5): Very well developed; directed laterodorsad; antler-shaped with a large branch and 2 small teeth on anterior side and 1 smaller spine on posterior side. Ozopore located between the first tooth and main branch of paraterga, visible in dorsal view. Telson (Fig. 6 C): Epiproct with several evident setiferous knobs near tip; tip with four spinnerets; lateral tubercles well developed. Hypoproct sub-trapeziform, with two distolateral, completely separated, setiferous knobs. Legs: Extremely long, slender and thin, c. 1.5 – 1.6 times as long as midbody height. Prefemora not swollen. Male femora 6 each ventrally with a large, robust tubercle in middle. Sterna: with distinct cross-impression, no modification – except a large, sparsely setose, trapeziform lamina carrying two distal, separated lobes between male coxae 4 (Fig. 6 D). Gonopod (Fig. 7): Suberect. Coxite (co) cylindrical, much shorter than femorite, sparsely setose distodorsally. Prefemorite (pref) densely setose, shorter than femorite as well. Femorite (fe) slightly enlarged distad, without a demarcation with postfemoral region. Postfemoral region slightly twisted mesad. Solenophore (sph) well developed; lamina medialis (lm) broadly rounded, partly folded to sheathe distal part of solenomere, lamina lateralis (ll) well developed. Seminal groove running entirely on mesal side, then entering a flagelliform solenomere (sl) which is partly sheathed by solenophore. Tip of gonopod consisting of seven overlapping laminae (Fig. 7 G).	en	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: 247-262, DOI: 10.3897/zookeys.1223.139649
831524D8E34E5890B8622D92AB730445.taxon	description	Figs 1, 2, 3, 4	en	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: 247-262, DOI: 10.3897/zookeys.1223.139649
831524D8E34E5890B8622D92AB730445.taxon	diagnosis	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).	en	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: 247-262, DOI: 10.3897/zookeys.1223.139649
831524D8E34E5890B8622D92AB730445.taxon	etymology	Etymology. The name refers to “ piccolo ”, a main character of the Japanese manga “ Dragon balls ” by Toriyama Akira (Japan). Noun in apposition.	en	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: 247-262, DOI: 10.3897/zookeys.1223.139649
831524D8E34E5890B8622D92AB730445.taxon	description	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): 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): 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). 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, 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): Epiproct without conspicuous setiferous knobs near tip, but broadly truncated; tip with four spinnerets; lateral tubercles well developed (Fig. 3 A). Hypoproct subtrapeziform, with two distolateral, completely separated, setiferous knobs (Fig. 3 B). 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, 3 C). Sterna: With distinct cross-impressions, no modification – except a large, sparsely setose, bifid, trapeziform lamina between male coxae 4 (Figs 1 A, 3 D). Gonopod (Fig. 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.	en	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: 247-262, DOI: 10.3897/zookeys.1223.139649
