Gigaxytes fusca Srisonchai, Enghoff & Panha

Srisonchai, Ruttapon, Enghoff, Henrik, Likhitrakarn, Natdanai & Panha, Somsak, 2018, A revision of dragon millipedes III: the new genus Gigaxytes gen. nov., with the description of three new species (Diplopoda, Polydesmida, Paradoxosomatidae), European Journal of Taxonomy 463, pp. 1-43: 11-16

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Gigaxytes fusca Srisonchai, Enghoff & Panha

gen. et sp. nov.

Gigaxytes fusca Srisonchai, Enghoff & Panha  gen. et sp. nov. DEEE 4BC36

( Figs 1View Fig. 1, 2View Fig. 2, 4–8View Fig. 4View Fig. 5View Fig. 6View Fig. 7View Fig. 8, 24View Fig. 24)


Collum usually with 5+5 cones/spines in anterior row, 4+4 cones/spines in intermediate row and 4+4 cones/spines in posterior row. Metaterga 2–8 usually with 4+4 cones/spines in anterior row, 4+4 cones/ spines in intermediate row and 4+4 cones/spines in posterior row. Male femora 5 and 6 with an apophysis. Similar in these repects to G. suratensis  gen. et sp. nov., but differs from this species by having brown body colouration; paraterga longer; male femora 7 unmodified; solenophore narrow laterally; lamina medialis apically sharp.


The specific epithet is a Latin adjective meaning brown and refers to the brown body colour of living specimens.

Material examined

Holotype THAILAND: ♂, Chumphon Province, Pathio District, Phitsadarn Cave ( Tham Phitsadarn ), 10º45′36″ N, 99°13′46″ E, ca. 103 m a.s.l., 29 Aug. 2015, ASRU members leg. ( CUMZ-pxDGT00166).GoogleMaps 

Paratypes THAILAND: 7 ♂♂, 1 ♀, same data as for holotype ( CUMZ-pxDGT00167-174);  1 ♂, 1 ♀, same data as for holotype ( ZMUC 00040247View Materials)  .

Additional specimens

MYANMAR: 9 ♂♂, 5 ♀♀, 1 juveniles, Tanintharyi Region, Lenya National Park, approximately 10 km from Nam Yen Village, Phayarhtan Cave ( Buddha Cave ), 11º13′50″ N, 99°10′35″ E, ca. 85 m a.s.l., 6 Jun. 2015, Fauna & Flora International staffs, C. Sutcharit, R. Chanabun and R. Srisonchai leg. ( CUMZAbout CUMZ).GoogleMaps  THAILAND: 1 broken ♂ – right gonopod lost, Chumphon Province, Pathio District, Phitsadarn Cave ( Tham Phitsadarn ), 10º45′36″ N, 99°13′46″ E, ca. 103 m a.s.l., 2 Oct. 2006, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 broken ♀, Prachuap Khiri Khan Province, Bang Saphan District, Wat Khao Tham Ma Rong , 11º12′05″ NAbout N, 99°29′52″ EAbout E, ca. 21 m a.s.l., 12 Oct. 2008, ASRU members leg. ( CUMZAbout CUMZ)GoogleMaps  .


SIZE. Length 35–38 mm (male), 35–40 mm (female); width of midbody metazona ca. 2.8 mm (male), 3.7 mm (female). Width of head <collum <2 <3 ≤ 4 <5–17, thereafter body gradually tapering towards telson.

COLOUR ( Fig. 4 AAbout A – CAbout CView Fig. 4). Specimens in life with body brown; head, collum, antennae, metaterga, prozona, surface below paraterga (upper part), paraterga, epiproct and legs brown; surface below paraterga (lower part), base of paraterga, sterna and a few basal podomeres pale brown. Colour in alcohol: after 10 years changed to pale brown; head, collum, metaterga, paraterga, surface below paraterga, sterna, epiproct pale brown or whitish brown.

COLLUM ( Figs 2 AAbout A, CView Fig. 2, 5AView Fig. 5). With three transverse rows of setiferous cones/spines, 5(6)+5 cones/spines in anterior row, 4(3/5)+4(3) cones/spines in intermediate row and 4(5)+4(3) cones/spines in posterior row (lateral cones/spines of anterior row located at base of collum paraterga; lateral cones/spines of posterior row displaced anteriad almost halfway to intermediate row); paraterga of collum elevated at ca. 40º –50º.

ANTENNAE ( Fig. 5DView Fig. 5). Very long and slender, reaching to body ring 6 or 7 (male) and 5 or 6 (female) when stretched dorsally.

TEGUMENT. Stricture between prozona and metazona wide, quite shallow.

METATERGA ( Figs 2A, D, GView Fig. 2, 5A –CView Fig. 5). With three transverse rows of setiferous cones/spines; metaterga 2–8 with 4(3/5)+4(3/5) cones/spines in anterior row, 4(3/5)+4(3/5) cones/spines in intermediate row and 4(3/5)+4(3/5) cones/spines in posterior row; metaterga 9–19 with 6(5)+6(5) cones/spines in anterior row, 6(5/7/8)+6(5/7) cones/spines in intermediate row and 6(5/7)+6(5/7) cones/spines in posterior row; lateral cones/spines of posterior row larger and longer than others in some specimens.

PLEUROSTERNAL CARINAE. On body ring 2 long, crest-like; on ring 3 a short ridge; thereafter missing.

PARATERGA ( Figs 2A –B, D –E, G –HView Fig. 2, 5A –C, FView Fig. 5, 6A –BView Fig. 6). Extremely long; directed caudolaterad on body rings 2–16, elevated at ca. 50º –70º (male) 50º –60º (female), directed increasingly caudad on body rings 17–19.

TELSON ( Figs 2F, L –NView Fig. 2, 6C –GView Fig. 6). Tip of epiproct subtruncate; apical tubercles inconspicuous. Hypoproct subtrapeziform; caudal margin subtruncate, with conspicuous setiferous tubercles.

STERNUM ( Figs 2KView Fig. 2, 6H –JView Fig. 6). On body ring 5 with a swollen lobe; posterior surface of lobe with a pore borne on a long cylindrical stalk.

LEGS ( Figs 2JView Fig. 2, 6E –GView Fig. 6). Male femora 5 and 6 with an apophysis.

GONOPODS ( Figs 7–8View Fig. 7View Fig. 8). Coxa subequal in length to femorite. Cannula quite long and slender. Femorite quite long, a bit stout, curved. Solenophore narrow laterally: lamina lateralis narrow: lamina medialis quite long and narrow, distally sharp, tip in situ directed ventrad.

Distribution and habitat

Known only from Thailand (Chumphon and Prachuap Khiri Khan Provinces) and Myanmar (Lenya National Park). All specimens were encountered hiding under dead leaves in limestone habitats and some were found in syntopy with Desmoxytes planata ( Pocock, 1895)  at Phitsadarn Cave and Wat Khao Tham Ma Rong, or with D. cervina ( Pocock, 1895)  at Phayarhtan Cave. The new species appears to have a limited distribution near the Kra Isthmus (narrowest part of the Malay Peninsula), a few locations have been recorded in Thailand and Myanmar. We regard this species to be endemic in this area. The type locality is a tourist attraction place, being a cave belonging to a bureau of monks. Some parts of a habitat where lot of specimens were collected in front of the cave are currently being destroyed, this has raised a concern about habitat loss for G. fusca  gen. et sp. nov.


Brown live specimens blended perfectly with the brown leaf litter on the ground, making them difficult to find. Specimens from Myanmar showed the same morphological characters as found in Thai material – no intrapopulational and interpopulational variations were found. On some specimens we found small white phoretic deutonymphs (the ‘hypopus’ stage) of mites of the family Histiostomatidae  ( Astigmata  ) ( Fig. 4D, EView Fig. 4). The mites can usually be found on specific sites especially on metaterga or paraterga, attaching to areas with a smooth surface.


Chulalongkorn University Museum of Natural History


Nanjing University


Royal Botanic Garden Edinburgh


Harvard University - Arnold Arboretum


University of Copenhagen