Gigaxytes parvoterga 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: 24-31

publication ID

https://doi.org/10.5852/ejt.2018.463

publication LSID

lsid:zoobank.org:pub:urn:lsid:zoobank.org:pub:0A1234C2-BE04-4EFE-9EB7-8F91E8485327

persistent identifier

http://treatment.plazi.org/id/038C7E3D-FF9E-C42E-60B9-FBAF1FF9FD1D

treatment provided by

Plazi

scientific name

Gigaxytes parvoterga Srisonchai, Enghoff & Panha
status

gen. et sp. nov.

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

urn:lsid:zoobank.org:act:6D14B1A7-3F10-4502-93FE-52 CAD 606C93D

( Figs 14–18View Fig. 14View Fig. 15View Fig. 16View Fig. 17View Fig. 18, 24 View Figure )

Diagnosis

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).

Etymology

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

Holotype 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).GoogleMaps 

Paratypes 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. ( CUMZAbout 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. ( CUMZAbout CUMZ). 

Description

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. 14A–B View Figure ). 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 Figure ). 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 Figure ). 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. 15A–C View Figure ). 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 15A–C, F View Figure , 16A–B View Figure ). 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. 16C–G View Figure ). Tip of epiproct subtruncate; apical tubercles inconspicuous. Hypoproct usually subsemicircular (some specimens subtrapeziform); caudal margin slightly round, with conspicuous setiferous tubercles.

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

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

GONOPODS ( Figs 17–18View Fig. 17View Fig. 18). 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  .

Remarks

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.

CUMZ

Chulalongkorn University Museum of Natural History