Gigaxytes parvoterga Srisonchai, Enghoff & Panha, Srisonchai, Enghoff & Panha, 2018

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 : 24-31

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Gigaxytes parvoterga Srisonchai, Enghoff & Panha

gen. et sp. nov.

Gigaxytes parvoterga Srisonchai, Enghoff & Panha gen. et sp. nov.

( Figs 14–18 View Fig View Fig View Fig View Fig View Fig , 24 View Fig )


Male femora 5, 6 and 7 with an apophysis. Similar in this respect to G. suratensis gen. et sp. nov., but differs from this by having paraterga shorter; collum usually with 3+3 cones/spines (intermediate row); metaterga 2–8 usually with 4+4 cones/spines (anterior row), 3+3 cones/spines (intermediate row) and 3+3 cones/spines (posterior row); metaterga 9–19 usually with 5+5 cones/spines (anterior row), 5+5 cones/spines (intermediate row) and 5+5 cones/spines (posterior row).


The specific epithet is a Latin noun in apposition, combining ‘ parvus ’ meaning small, and ‘ terga ’ referring to paraterga, and alludes to the shorter subspiniform paraterga compared to other species.

Material examined


THAILAND: ♂, Trang Province, Palian District, Tham Khao Ting , 7º09′30″ N, 99°48′10″ E, ca. 42 m a.s.l., 31 Aug. 2015, ASRU members leg. (CUMZ-pxDGT00175).



THAILAND: 5 ♂♂, 1 ♀, same data as for holotype (CUMZ-pxDGT00176-181).

Additional specimens

THAILAND: 1 juvenile, Trang Province, Palian District, Tham Khao Ting, 7º09′30″ N, 99°48′10″ E, ca. 42 m a.s.l., 31 Aug. 2015, ASRU members leg. ( CUMZ); 2 ♀♀, Songkhla Province, Rattaphum District, Tham Sri Khaesorn (Sri Khaesorn Cave), 7º00′47″ N, 100°09′43″ E, ca. 348 m a.s.l., 12 Jan. 2009, ASRU members leg. ( CUMZ).


SIZE. Length 35–37 mm (male), 36–40 mm (female); width of midbody metazona ca. 3.0 mm (male), 3.4 mm (female). Width of head <collum <2 = 3 <4 <5–16, thereafter body gradually tapering towards telson.

COLOUR ( Fig. 14 View Fig A–B). Specimens in life with body pinkish brown (recently moulted adult brownish pink); head and antennae (except distal part of antennomere 7 and antennomere 8 whitish); metaterga, prozona and surface below paraterga pinkish brown; a dark brown triangular zone on metaterga of each ring; collum, epiproct and legs brown; paraterga dark brown; sterna and a few basal podomeres pale brown; tip of paraterga white. Colour in alcohol: after 9 years changed to brown; head, antennae, collum, metaterga, paraterga, surface below paraterga, sterna, epiproct and legs brown or pale brown.

COLLUM ( Fig. 15A View Fig ). With three transverse rows of setiferous cones/spines, 5(6)+5(6) cones/spines in anterior row, 3(4/5)+3(4) cones/spines in intermediate row and 4(3)+4 cones/spines in posterior row (lateral cones/spines of anterior row located at base of collum paraterga; paraterga of collum elevated at ca. 20º–40º.

ANTENNAE ( Fig. 15D View Fig ). Moderately long and slender, reaching to body ring 5 or 6 (male) and 4 or 5 (female) when stretched dorsally.

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

METATERGA ( Fig. 15 View Fig A–C). With three transverse rows of setiferous cones/spines; metaterga 2–8 with 4(5)+4(5) cones/spines in anterior row, 3(4/5)+3(4/5) cones/spines in intermediate row and 3(4)+3(4/5) cones/spines in posterior row; 9–19 with 5(6)+5(6) cones/spines in anterior row, 5(4/6)+5(4/6) cones/ spines in intermediate row and 5(4/6/7)+5(4/6/7) 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 long ridge; on ring 4 a short ridge; thereafter missing.

PARATERGA ( Figs 15 View Fig A–C, F, 16A–B). Moderately long, directed caudolaterad on body rings 2–16, elevated at ca. 40º–50º (male) 30º–40º (female), directed increasingly caudad on body rings 17–19.

TELSON ( Fig. 16 View Fig C–G). Tip of epiproct subtruncate; apical tubercles inconspicuous. Hypoproct usually subsemicircular (some specimens subtrapeziform); caudal margin slightly round, with conspicuous setiferous tubercles.

STERNUM ( Fig. 16 View Fig H–J). On body ring 5 with a swollen lobe; posterior surface of lobe with a pore borne on a short cylindrical stalk.

LEGS ( Fig. 15 View Fig E–H). Male femora 5, 6 and 7 with an apophysis.

GONOPODS ( Figs 17–18 View Fig View Fig ). Coxa longer than prefemoral part, subequal in length to femorite. Cannula quite short and stout. Femorite long and slender, curved. Solenophore wide laterally: lamina lateralis broad: lamina medialis very wide, distally blunt, in situ directed ventrad.

Distribution and habitat

Known only from a small area in Trang and Songkhla Provinces. All specimens were collected in limestone habitats during the rainy season. Adults males and females were seen hiding under dead leaves while juveniles were found crawling on leaf litter. It is noteworthy that despite several intensive surveys during 2016–2017 in Trang and Songkhla as well as nearby areas, no further specimens of this species have yet been found. We consider G. parvoterga gen. et sp. nov. as an endemic species for Thailand. The new species has been found in syntopy with Desmoxytes delfae and Desmoxytes flabella Srisonchai, Enghoff & Panha, 2018 .


Specimens blended perfectly with the environment by hiding under brown/red leaves, it therefore was really difficult to find them. We could not find males at Tham Sri Khaesorn, only two females were collected, but the morphological characters of these perfectly agree with a female specimen from the type locality. Gigaxytes parvoterga gen. et sp. nov. exhibits some variation in shape of hypoproct: subtrapeziform in some specimens, subsemicircular in the others.


Cameroon University, Museum of Zoology