Gigaxytes fusca Srisonchai, Enghoff & Panha 2018, gen. et sp. nov.
Creators: name: Srisonchai, Ruttapon
name: Enghoff, Henrik
name: Likhitrakarn, Natdanai
name: Panha, Somsak
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Polydesmida
Paradoxosomatidae
Gigaxytes
Gigaxytes fusca

description: Gigaxytes fusca Srisonchai, Enghoff & Panha gen. et sp. nov.
urn:lsid:zoobank.org:act: 9995F35F-6B9B-47E9-992A-1E2DEEE4BC36
(Figs 1, 2, 4–8, 24)
Diagnosis
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.
Etymology
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).
Paratypes
THAILAND: 7 ♂♂, 1 ♀, same data as for holotype (CUMZ-pxDGT00167-174); 1 ♂, 1 ♀, same data as for holotype (ZMUC 00040247).
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. (CUMZ). – 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. (CUMZ); 1 broken ♀, Prachuap Khiri Khan Province, Bang Saphan District, Wat Khao Tham Ma Rong, 11º12′05″ N, 99°29′52″ E, ca. 21 m a.s.l., 12 Oct. 2008, ASRU members leg. (CUMZ).
Description
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 A–C). 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 2A, C, 5A). 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. 5D). 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, G, 5 A–C). 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 2 A–B, D–E, G–H, 5A–C, F, 6A–B). 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–N, 6C–G). Tip of epiproct subtruncate; apical tubercles inconspicuous. Hypoproct subtrapeziform; caudal margin subtruncate, with conspicuous setiferous tubercles.
STERNUM (Figs 2K, 6 H–J). On body ring 5 with a swollen lobe; posterior surface of lobe with a pore borne on a long cylindrical stalk.
LEGS (Figs 2J, 6 E–G). Male femora 5 and 6 with an apophysis.
GONOPODS (Figs 7–8). 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.
Remarks
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, E). The mites can usually be found on specific sites especially on metaterga or paraterga, attaching to areas with a smooth surface.
Gigaxytes gigas (Golovatch & Enghoff, 1994) gen. et comb. nov.
(Figs 3, 9–13, 24)
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].
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. (CUMZ); 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. (CUMZ); 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. (CUMZ); 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. (CUMZ); 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. (CUMZ); 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. (CUMZ); 2 ♂♂, 1 ♂ – gonopods lost, 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. (CUMZ); 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. (CUMZ); 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. (CUMZ); 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. (ZMUC); 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. (CUMZ); 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); 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); 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); 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). – 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. (CUMZ); 1 ♂, 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. (CUMZ); 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. (CUMZ). – 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. (CUMZ); 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. (CUMZ); 1 ♂ – gonopods lost, Si Banphot District, Khao Pu-Khao Ya National Park, 11 Jan. 2009, ASRU members leg. (CUMZ); 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. (CUMZ); 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. (CUMZ); 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. (CUMZ); 2 ♂♂, 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. (CUMZ). – 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. (CUMZ); 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. (CUMZ); 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. (CUMZ); 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. (CUMZ); 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. (CUMZ); 5 ♂♂, 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. (CUMZ).
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. 9 A–E). 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). 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). 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. 10 A–C). 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 10 A–C, H, 11A–B). 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. 11 C–G). 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. 11 H–J). On body ring 5 with a swollen lobe; posterior surface of lobe with a pore, pore not borne on a stalk.
LEGS (Fig. 11 E–G). Male femora without modification (Male femora 5, 6 and 7 unmodified).
GONOPODS (Figs 3, 12–13). 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) 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.
description: Published as part of 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), pp. 1-43 in European Journal of Taxonomy 463 on pages 11-24, DOI: 10.5852/ejt.2018.463, http://zenodo.org/record/1467258