Gigaxytes gigas ( Golovatch & Enghoff, 1994 )

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: 16-24

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-FF86-C427-60AC-FD701E1CFC73

treatment provided by

Plazi

scientific name

Gigaxytes gigas ( Golovatch & Enghoff, 1994 )
status

gen. et comb. nov.

Gigaxytes gigas ( Golovatch & Enghoff, 1994)  gen. et comb. nov.

( Figs 3 View Figure , 9–13View Fig. 9View Fig. 10View Fig. 11View Fig. 12View Fig. 13, 24 View Figure )

Desmoxytes gigas Golovatch & Enghoff, 1994: 56  , figs 49–52.

Desmoxytes gigas  – Enghoff 2005: 96. — Nguyen & Sierwald 2013: 1241.

Diagnosis

Collum usually with 5+5 cones/spines in anterior row, 3+3 cones/spines in intermediate row and 4+4 cones/spines in posterior row. Similar in this respect to G. parvoterga  sp. nov. Differs from this species by having paraterga longer; the degree of elevation of paraterga higher; male femora 5, 6 and 7 unmodified.

Material examined

Holotype THAILAND: ♀, Krabi Province, road between Krabi and Phuket, 10 km South of Krabi , 8º09′ N, 98°50′ E, lowland rainforest, <200 m, 13 Oct. 1991, M. Anderson, O. Martin & N. Scharff leg. ( ZMUC000101460) [the exact location is 10 km North of Krabi].GoogleMaps 

Additional specimens

THAILAND – Krabi Province: 1 broken ♂ – gonopods lost, Ao Luek District , Than Bok Khorani, 8º23′28″ N, 98°44′07″ E, 15 Jan. 2014, ca. 46 m a.s.l., ASRU members leg. ( CUMZAbout CUMZ)GoogleMaps  ; 2 ♀♀, Ao Luek District , Than Bok Khorani, 8º23′28″ N, 98°44′07″ E, ca. 46 m a.s.l., 23 Aug. 2014, P. Pimvichai, P. Prasankok and N. Nantarat leg. ( CUMZAbout CUMZ)GoogleMaps  ; 1 juvenile, Ao Luek District , Than Bok Khorani, 8º23′28″ N, 98°44′07″ E, ca. 46 m a.s.l., 30 Aug. 2015, P. Pimvichai, P. Prasankok and N. Nantarat leg. ( CUMZAbout CUMZ)GoogleMaps  ; 1 ♀, Ao Luek District, Than Bok Khorani, 8º23′28″ N, 98°44′07″ E, ca. 46 m a.s.l., 12 Mar. 2017, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 ♂ – gonopods lost, Muaeng Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8º07′38″ N, 98°55′26″ E, ca. 87 m a.s.l., 25 Oct. 2007, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 broken ♀, Muaeng Krabi District , Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8º07′38″ N, 98°55′26″ E, ca 87 m a.s.l., 15 Jan. 2009, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  2 ♂♂, 1 ♂ – gonopods lostGoogleMaps  , 2 ♀♀, Muaeng Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8º07′38″ N, 98°55′26″ E, ca 87 m a.s.l., 18 May 2010, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 ♂, 2 ♀♀, Muaeng Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8º07′38″ N, 98°55′26″ E, ca. 87 m a.s.l., 15 Jan. 2013, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  9 ♂♂, 3 ♀♀, Muaeng Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8º07′38″ N, 98°55′26″ E, ca. 87 m a.s.l., 24 Aug. 2014, leg. ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 ♂, 1 ♀, Muaeng Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8º07′38″ N, 98°55′26″ E, ca. 87 m a.s.l., 24 Aug. 2014, ASRU members leg. ( ZMUCAbout ZMUC);GoogleMaps  6 ♂♂, 5 ♀♀, Muaeng Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8º07′38″ N, 98°55′26″ E, ca. 87 m a.s.l., 30 Aug. 2015, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  3 ♂♂, 3 ♀♀, Muaeng Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8º07′38″ N, 98°55′26″ E, ca. 87 m a.s.l., 9 Jul. 2017, ASRU members leg. (CUMZ);GoogleMaps  1 ♂, Muaeng Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8º07′38″ N, 98°55′26″ E, ca. 87 m a.s.l., 25 Jul. 2017, ASRU members leg. (CUMZ);GoogleMaps  1 ♂, Muaeng Krabi District , near Ban Na Mee , Tham Na Mee (Na Mee Cave), 8º08′12″ N, 98°48′23″ E, ca. 70 m a.s.l., 30 Aug. 2015, ASRU members leg. (CUMZ);GoogleMaps  2 ♂♂, Plai Phraya District , Wat Khao Hua Sing, 8º30′47″ N, 98°45′34″ E, ca. 155 m a.s.l., 12 Mar. 2017, ASRU members leg. (CUMZ).GoogleMaps  Nakhon Si Thammarat Province: 1 ♀, Thung Song District, Weruwan Bureau of Monks (Tham Rad), 8º02′48″ N, 99°43′43″ E, ca. 83 m a.s.l., 11 Jan. 2009, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 ♂GoogleMaps  , 2 ♀♀, Thung Song District , Talod Cave Park (Talod Cave), 8º09′32″ N, 99°40′42″ E, ca. 74 m a.s.l., 5 Jan. 2017, ASRU members leg. ( CUMZAbout CUMZ)GoogleMaps  ; 1 ♀, Nopphitam District , Krung Ching Waterfall, 8º43′27″ N, 99°40′04″ E, ca. 173 m a.s.l., 17 Jan. 2013, ASRU members leg. ( CUMZAbout CUMZ).GoogleMaps  Phatthalung Province: 1 ♂ – gonopods lost, Khuan Khanun District, Tham Wang Thong, 7º40′57″ N, 100°00′58″ E, ca. 44 m a.s.l., 11 Jan. 2009, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  2 broken ♀♀, Khuan Khanun District, Tham Wang Thong, 7º40′57″ N, 100°00′58″ E, ca. 44 m a.s.l., 6 Jul. 2017, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 ♂ – gonopods lost, Si Banphot District , Khao Pu-Khao Ya National Park, 11 Jan. 2009, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 ♂, Srinagarindra District , Wat Tham Sumano (Sumano Cave Temple), 7º35′08″ N, 99°52′08″ E, ca. 75 m a.s.l., 23 Oct. 2010, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  6 ♂♂, Srinagarindra District , Wat Tham Sumano (Sumano Cave Temple), 7º35′08″ N, 99°52′08″ E, ca. 75 m a.s.l., 16 Jan. 2013, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 ♂, Srinagarindra District , Wat Tham Sumano (Sumano Cave Temple), 7º35′08″ N, 99°52′08″ E, ca. 75 m a.s.l., 16 Jan. 2013, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  2 ♂♂GoogleMaps  , 1 ♀, Kong Ra District , Khao Phaya Hong, 7º27′46″ N, 99°57′50″ E, ca. 55 m a.s.l., 6 Jul. 2017, ASRU members leg. ( CUMZAbout CUMZ).GoogleMaps  Trang Province: 1 ♀, Hui Yot District, Khao Phra Yot, Bua Nguen-Bua Thong Pagoda, 7º48′10″ N, 99°37′05″ E, ca. 66 m a.s.l., 14 Jan. 2009, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  4 ♂♂, Hui Yot District , Wat Khao Huai Hang, 7º47′37″ N, 99°38′40″ E, ca. 83 m a.s.l., 24 Aug. 2014, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 broken ♂ – gonopods lost, 1 ♀, Na Yong District , Khao Chang Hai Cave, 7º35′23″ N, 99°40′08″ E, ca. 35 m a.s.l., 15 Jan. 2009, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 ♂, 2 ♀♀, Na Yong District , Khao Chang Hai Cave, 7º35′23″ N, 99°40′08″ E, ca. 35 m a.s.l., 25 Aug. 2014, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  1 ♂, 2 juveniles, Na Yong District , Khao Chang Hai Cave, 7º35′23″ N, 99°40′08″ E, ca. 35 m a.s.l., 9 Jul. 2017, ASRU members leg. ( CUMZAbout CUMZ);GoogleMaps  5 ♂♂GoogleMaps  , 3 ♀♀, Ratsada District , Wat Tham Phra Phut, 7º57′42″ N, 99°44′42″ E, ca. 103 m a.s.l., 5 Jul. 2017, ASRU members leg. ( CUMZAbout CUMZ).GoogleMaps 

Redescription (first description of male)

SIZE. Length 30–40 mm (male), 34–40 mm (female); width of midbody metazona ca. 3.0 mm (male), 3.5 mm (female). Width of head <collum <2 ≤ 3 ≤ 4 <5–16, thereafter body gradually tapering towards telson.

COLOUR ( Fig. 9A–E View Figure ). Specimens in life with body brownish pink/pinkish brown; head and antennae brown/dark brown (except distal part of antennomere 7 and antennomere 8 whitish); prozona, metaterga and surface below paraterga brownish pink/pinkish brown; paraterga dark brown/black; collum, epiproct and leg brown; tip of paraterga, sterna and a few basal podomeres pale brown. Colour in alcohol: after 5–16 years changed to pale brown; head, antennae, collum, metaterga, paraterga, surface below paraterga, sterna, epiproct and legs pale brown.

COLLUM ( Fig. 10A View Figure ). With three transverse rows of setiferous cones/spines, 5(6)+5(6) cones/spines in anterior row, 3(4/5)+3(4/5) cones/spines intermediate row and 4(3)+4(3) cones/spines in posterior row (lateral cones/spines of anterior row located at base of collum paraterga); paraterga of collum elevated at ca. 30º–40º.

ANTENNAE ( Fig. 10D View Figure ). Very long and slender, reaching to body ring 7 or 6 (male) and 5 or 4 (female) when stretched dorsally.

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

METATERGA ( Fig. 10A–C View Figure ). With three transverse rows of setiferous cones/spines; metaterga 2–8 with 4(5)+4(5) cones/spines in anterior row, 4(3/5)+4(3/5) cones/spines in intermediate row and 4(3)+4(3) cones/spines in posterior row; metaterga 9–19 with 5(4/6)+5(4/6) cones/spines in anterior row, 5(4)+5(4) cones/spines in intermediate row and 5(4/6)+5(4/6) cones/spines in posterior row.

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 10A–C, H View Figure , 11A–B View Figure ). Moderately long, directed caudolaterad on body rings 2–17, elevated at ca. 50º–70º (male) 40º–60º (female), directed increasingly caudad on body rings 18 and 19.

TELSON ( Fig. 11C–G View Figure ). Tip of epiproct usually subtruncate (in some specimens slightly emarginate); apical tubercles inconspicuous. Hypoproct usually subtrapeziform (in some specimens subrectangular); caudal margin subtruncate, with conspicuous setiferous tubercles (in specimens from Khao Phaya Hong inconspicuous).

STERNUM ( Fig. 11H–J View Figure ). On body ring 5 with a swollen lobe; posterior surface of lobe with a pore, pore not borne on a stalk.

LEGS ( Fig. 11E–G View Figure ). Male femora without modification (Male femora 5, 6 and 7 unmodified).

GONOPODS ( Figs 3 View Figure , 12–13View Fig. 12View Fig. 13). Coxa subequal in length to femorite or longer than femorite. Cannula quite short and stout. Femorite long and slender, curved. Solenophore wide laterally: lamina lateralis broad: lamina medialis wide, distally blunt, in situ directed mesoventrad.

Distribution and habitat

Gigaxytes gigas  gen. et comb. nov. is presently known only from Krabi, Nakhon Si Thammarat, Phatthalung and Trang Provinces. Specimens were collected from limestone habitats and were mostly seen hiding under dead leaves, sometimes crawling on leaf litter. It has been found in syntopy with two species of other dragon millipedes at several locations across its distribution: Desmoxytes cervina  and Desmoxytes delfae ( Jeekel, 1964)  . Notably, G. gigas  gen. et comb. nov. was usually seen living and crawling on the ground whereas D. cervina  and D. delfae  were collected from rocks and tree branches.

Based on extensive fieldwork focused on this genus in southern Thailand, G. gigas  gen. et comb. nov. is one of the most common and widely distributed dragon millipedes in many provinces. It is sometimes encountered close to the areas that have been developed as tourist attractions such as caves, as well as a temple or bureau of monks. However, it is still found in natural habitats and has a rather limited distribution in southern Thailand; we here regard this species as endemic for the Thai fauna.

Note on material

Desmoxytes  gigas Golovatch & Enghoff, 1994  was described on the basis of a single adult female (in ZMUC) collected from Krabi Province. We have collected additional specimens in many areas, males as well as females. After examination of all material, it is clear that morphological characters of adult females collected from Krabi, Nakhon Si Thammarat, Phatthalung and Trang Provinces match perfectly with the female holotype.

Remarks

The living colouration of adults is generally pinkish brown that blends perfectly with brown/pinkish brown leaves or litter on the ground; juveniles are brown.

Two main populations, eastern and western, can be distinguished on the basis of morphological differences in combination with distribution. The two populations differ in characters of paranota and gonopod femorite: specimens of the western population have obviously longer paraterga and the femorite more slender than those of the eastern one. Intrapopulational variation also exists: epiproct with conspicuous apical setiferous tubercles in some specimens, inconspicuous in others; hypoproct subtrapeziform in some specimens, subrectangular in others.

Some specimens of G. gigas  gen. et comb. nov. were infested with parasitic mite larvae, probably belonging to the genus Leptus Latreille, 1896. Several mites appeared on metaterga in anteriormost rings and could easily be discerned ( Fig. 9B, C View Figure ) by their remarkable orange colour. Mite larve assigned to the genus Leptus were reported from a few dragon millipede species (genera Desmoxytes  and Nagaxytes  ) by Srisonchai et al. (2018a, b). We suspect that all? Leptus larvae from dragon millipedes might belong to the same species. However, an exact identification of the mite species has not been undertaken, and in any case, the relationship between the millipede and Leptus still requires further studies.

As mentioned in the diagnosis, the new species is noticeably different from other Gigaxytes  species due to its unmodified male femora 5–7.

CUMZ

Chulalongkorn University Museum of Natural History

ZMUC

Zoological Museum, University of Copenhagen

Kingdom

Animalia

Phylum

Arthropoda

Class

Diplopoda

Order

Diplopoda

Family

Paradoxosomatidae

Genus

Gigaxytes

Loc

Gigaxytes gigas ( Golovatch & Enghoff, 1994 )

Srisonchai, Ruttapon, Enghoff, Henrik, Likhitrakarn, Natdanai & Panha, Somsak 2018

2018
Loc

Desmoxytes gigas Golovatch & Enghoff, 1994 : 56

Golovatch & Enghoff, 1994 : 56

Loc

Desmoxytes gigas

Enghoff 2005 : 96 Nguyen & Sierwald 2013 : 1241