Gigantomorpha mesilauensis Ng & Srisonchai & Golovatch & Sutcharit & Panha & Latim & Likhitrakarn 2025, sp. nov.
Creators: name: Ng, Ting Hui
name: Srisonchai, Ruttapon
name: Golovatch, Sergei I.
name: Sutcharit, Chirasak
name: Panha, Somsak
name: Latim, Martinah
name: Likhitrakarn, Natdanai
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Polydesmida
Paradoxosomatidae
Gigantomorpha
Gigantomorpha mesilauensis

description: Gigantomorpha mesilauensis Ng & Likhitrakarn sp. nov.
urn:lsid:zoobank.org:act: 6000B413-08B8-4250-97D8-F6D9E50E1C62
Figs 5–7
Diagnosis
This new species closely resembles G. sayapensis sp. nov., especially in that both species have the gonopod tip small bifid without distinct branching. However, it is distinguished by the less strongly bordered paraterga (Fig. 5A, C, F) (vs strongly bordered; Fig. 8B, D, F), the sternal cones present only between male coxae 4 (vs between both male coxae 4 and 5), and the gonopodal lamina lateralis (ll) and lamina medialis (lm) subequal in length, long, and slender, slightly narrowed apically (Figs 6A, C, E, 7A–B) (vs lamina medialis (lm) larger and expanded apically, Figs 3A–D, 4A–B).
Etymology
To emphasise the type locality, adjective in feminine gender.
Material examined
Holotype
MALAYSIA • ♂; Borneo, Sabah, Ranau, Mesilau Nature Resort, Nepenthes Trail; 6°02′45.4″ N, 116°35′49.1″ E; 1926 m a.s.l., 26 Sep. 2023; T.H. Ng, F. Anthony, E.S.H. Quah, J. Dulipat, F.J. Chong, A. Joseph and C.L. Soo leg.; BOR/MYR 90.
Paratypes
MALAYSIA • 1 ♂; same data as for holotype; SP 14837 • 1 ♂; same data as for holotype; BOR/MYR 85 • 1 ♂; Borneo, Sabah, Ranau, Mesilau Nature Resort, Tambang Gate; 6°02′41.7″ N, 116°35′45.0″ E; 1922 m a.s.l.; 27 Sep. 2023; T.H. Ng, F. Anthony and F.J. Chong leg.; BOR/MYR 111 • 1 ♀; same data as for preceding; SP 14838 • 1 ♀; same data as for preceding; BOR/MYR 108 • 1 ♂; Borneo, Sabah, Ranau, Kinabalu Park, Mount Tambuyokon; 6°12′24.5″ N, 116°40′13.9″ E; 2012 m a.s.l.; 11 May 2023; T.H. Ng, F. Anthony and T.S. Liew leg.; SP 14839 • 1 ♀; Borneo, Sabah, Ranau, Kinabalu Park, Mount Tambuyokon; 6°12′22.5″ N, 116°40′06.7″ E; 2052 m a.s.l.; 11 May 2023; T.H. Ng, F. Anthony and T.S. Liew leg.; BOR/MYR 78 • 1 ♀; Borneo, Sabah, Ranau, Kinabalu Park, Mount Tambuyokon; 6°12′45.5″ N, 116°40′51.7″ E; 1398 m a.s.l.; 11 May 2023; T.H. Ng, F. Anthony and T.S. Liew leg.; SP 14840.
Description
Length 35.4–41.3 mm (♂) or 33.5–39.5 mm (♀), width of midbody pro- and metazonae 2.4–2.8 and 3.6–4.2 mm (♂) or 2.3–3.3 and 3.9–4.4 mm (♀), respectively. Holotype 37.4 mm long, and 2.7 and 4.1 mm wide on midbody pro- and metaterga, respectively.
Colouration of alcohol material after one year of preservation dark brown or castaneous brown with a pattern of contrasting yellowish brown paraterga and epiproct (Fig. 5A–G); antennae brown to light brown (Fig. 5B); venter and legs light brown to light yellowish (Fig. 5B, E–I).
Clypeolabral region and vertex sparsely setose, epicranial suture distinct.Antennae rather short (Fig. 5B), reaching body ring 3 (♂, ♀) when stretched dorsally. In length, antennomere 3 =2> 5>4 =6>> 1=7. Interantennal isthmus ca 0.6 times diameter of antennal socket (Fig. 8B). In width, head <collum <ring 3<2<4<5<6<7–16 (Fig. 5A), thereafter body gently and gradually tapering. Collum with three transverse rows of strong setae: 3+3 anterior, 2+2 intermediate, and 4+4 posterior; caudal corner very broadly rounded, paraterga declined ventrad, not produced past rear tergal margin (Fig. 5A–B).
Tegument rather smooth and shining, prozona delicately shagreened, metaterga smooth and leathery, posterior halves faintly rugulose, surface below paraterga microgranulate (Fig. 5A–F).
Postcollum metaterga each with two transverse rows of setae: an anterior transverse row with 2+2, often abraded setae traceable at least as insertion points, and a posterior row with 4(5)+4(5) setae borne on low, oblong, rounded tubercles or minute knobs with insertion points of mostly abraded setae. Tergal setae rather short, strong, slender, about 1/4 metatergal length. Axial line traceable both on pro- and metazona. Paraterga very strongly developed (Fig. 5A–G), especially well so in males, subhorizontal to mostly slightly upturned, lying above dorsum or slightly above dorsum, thin in lateral view, like blunt blades, a little thicker only on pore-bearing rings, on postcollum rings extending increasingly beyond dorsum, especially so in rings 17–19; anterior edge broadly rounded and narrowly bordered, fused to callus; caudal corner almost completely to fully pointed, always extending past rear tergal margin, bent posteriad on rings 17–19; posterior edge oblique (Fig. 5A, C, F). Calluses on poreless paraterga delimited by a sulcus only dorsally, but on pore-bearing rings paraterga both dorsally and ventrally. Paraterga 2 broad, lateral edge with three small acute denticles, one at midway, the other two each at posterior 1/3 (Fig. 5A). Paraterga 3 and 4 each with two similar evident incisions, one at midway, the other in posterior 1/3 (Fig. 5A). Following poreless rings with two evident incisions, one at midway, the other in posterior 1/3, caudal incision in pore-bearing rings smaller or gradually reduced in posterior rings (Fig. 5D, F). Ozopores evident, lateral, each lying in an ovoid groove at about 1/3 metatergal length in front of posterior edge of metaterga (Fig. 5C–E).
Transverse sulcus usually distinct (Fig. 5A, C, F), complete and visible on metaterga 5–18, rather deep and narrow, reaching the bases of paraterga, linear, ribbed at bottom. Stricture between pro- and metazona rather wide, deep, ribbed at bottom down to base of paraterga (Fig. 5A, C, F). Pleurosternal carinae complete crests only on rings 2 and 3 (Fig. 8B), each with an evident sharp denticle caudally, thereafter increasingly reduced until ring 8 (♂) or 7 (♀).
Epiproct (Fig. 5E–G) conical, flattened dorsoventrally, subtruncate, with two evident apical papillae directed caudally, both pointed at tip; pre-apical papillae evident, lying close to tip. Hypoproct subtrapeziform (Fig. 5G), small setigerous knobs at caudal edge well-separated and evident.
Sterna separsely setose, without modifications; cross-impressions shallow; two large and long, fully separated, sparsely setose, sternal cones between male coxae 4 (Fig. 5H–I). A paramedian pair of small tubercles in front of gonopod aperture. Legs long and slender, midbody ones ca 1.3–1.5 (♂) or 1.1–1.3 (♀) times as long as body height; prefemora without modifications; tarsal brushes present until legs of ring 17.
Gonopods (Figs 6–7) simple; coxa long and thick, subcylindrical, a little curved caudad, sparsely setose distoventrally (Figs 6A–B, 7A–B). Prefemoral part short, densely setose as usual, about 1/4 as long as femoral part + postfemoral part (Fig. 7A–B). Femoral part long and slender, slightly expanded distad, curved, postfemoral part demarcated by an oblique lateral sulcus (Figs 6A–B, D, F, 7A–B); seminal groove running entirely mesally along fermorite, solenomere (sl) flagelliform, fully sheathed by solenophore (sph). Both lamina lateralis (ll) and lamina medialis (lm) well developed, subequal in length, long and slender (Figs 6A, C, E, 7B). Lamina medialis (lm) with tip clearly bifid (Fig. 7A).
Remarks
This species was collected on rocks and vegetation, under rotten branches or logs, in lower montane forest habitats in the Mesilau and Mount Tambuyokon areas in the eastern part of the Kinabalu Park complex (Fig. 1C).
description: Published as part of Ng, Ting Hui, Srisonchai, Ruttapon, Golovatch, Sergei I., Sutcharit, Chirasak, Panha, Somsak, Latim, Martinah & Likhitrakarn, Natdanai, 2025, A taxonomic study of millipede genera, Orangutana Golovatch, 1996 and Gigantomorpha Jeekel, 1963 (Diplopoda, Polydesmida, Paradoxosomatidae), with description of four new species from Sabah, Borneo, East Malaysia, pp. 221-248 in European Journal of Taxonomy 987 on pages 229-233, DOI: 10.5852/ejt.2025.987.2871, http://zenodo.org/record/15275702