Desmoxytes takensis Srisonchai, Enghoff & Panha, 2016

Srisonchai, Ruttapon, Enghoff, Henrik, Likhitrakarn, Natdanai & Panha, Somsak, 2018, A revision of dragon millipedes I: genus Desmoxytes Chamberlin, 1923, with the description of eight new species (Diplopoda, Polydesmida, Paradoxosomatidae), ZooKeys 761, pp. 1-177 : 1

Desmoxytes takensis Srisonchai, Enghoff & Panha, 2016 Figs 82, 83

Desmoxytes takensis Srisonchai, Enghoff & Panha, 2016: 103.

Material examined. Holotype.

Male (CUMZ), THAILAND, Tak Province, Phobphra District, Nangkruen Waterfall, on litters and under decaying bark, 16°24'36.0"N, 98°41'21.0"E, ca. 383 m a.s.l., 15 January 2015, leg. R. Srisonchai, T. Seesamut, and P. Jirapatrasilp.

Paratypes.

12 males, 10 females, 1 juvenile (CUMZ), 2 males, 1 female (ZMUC), same data as holotype. 2 males, 1 female (CUMZ), same locality as holotype, 18 January 2011, leg. C. Sutcharit, R. Chanabun, N. Likhitrakarn and T. Krutchuen.

Further specimens,

all from THAILAND, Kamphaeng Phet Province: 2 males missing gonopods, 1 female, 2 males (CUMZ), Khlong Lan District, Khlong Lan Waterfall, 16°07'40"N, 99°17'11"E, ca. 189 m a.s.l., 31 May 2009, leg. S. Panha and ASRU members.

Tak Province, Tha Song Yang District: 1 male, 8 females, 2 broken males, 1 male missing gonopods, 1 male missing right gonopod (CUMZ), Km 89 on road no. 105 from Mae Sot to Mae Hong Son, limestone mountain, 18 July 2008, leg. S. Panha and ASRU members. 13 juveniles (CUMZ), Km 131 on road no. 105 from Mae Sot to Mae Hong Son, limestone moutain, 30 June 2015, leg. C. Sutcharit, R. Srisonchai and ASRU members.

Tak Province, Mae Sot District: 3 males (CUMZ), Chao Por Phawo Shrine, 16°46'19"N, 98°41'11"E, ca. 668 m a.s.l., 17 July 2010, leg. S. Panha and ASRU members. 4 males, 14 females, 1 broken male and missing gonopods, 6 broken males, (12 males, all remaining rings 1-8), many broken and mixed specimens (CUMZ), Chao Por Phawo Shrine, 16°46'19"N, 98°41'11"E, ca. 668 m a.s.l., 17 July 2010, leg. S. Panha and ASRU members. 1 male missing gonopods, 1 male, 1 broken male (CUMZ), Chao Por Phawo Shrine, 16°46'19"N, 98°41'11"E, ca. 668 m a.s.l., 26 September 2010, leg. S. Panha and ASRU members. 10 males, 8 females (CUMZ), Chao Por Phawo Shrine, 16°46'19"N, 98°41'11"E, ca. 668 m a.s.l., 29 June 2015, leg. C. Sutcharit and ASRU members. 15 mixed specimens (CUMZ), Chao Por Phawo Shrine, 16°46'19"N, 98°41'11"E, ca. 668 m a.s.l., 19 October 2015, leg. C. Sutcharit and R. Srisonchai. 3 females (CUMZ), Chao Por Phawo Shrine, 16°46'19"N, 98°41'11"E, ca. 668 m a.s.l., 27 July 2016, leg. P. Pimvichai, P. Prasankok, and N. Nantarat. 54 males, 16 females (CUMZ), 2 males, 1 female (ZMUC), 1 male (NHMW), 1 male (NHMUK), Chao Por Phawo Shrine, 16°46'19"N, 98°41'11"E, ca. 668 m a.s.l., 29 August 2016, leg. S. Panha and ASRU members. 15 specimens (CUMZ), Wat Tham Inthanin, 16°45'59"N, 98°40'21"E, ca. 671 m a.s.l., 19 October 2015, leg. C. Sutcharit and R. Srisonchai. 13 males, 11 females (CUMZ), Wat Pho Thi Khun (Wat Huai Toey), 16°45'42"N, 98°38'49"E, ca. 432 m a.s.l., 29 August 2016, leg. C. Sutcharit and R. Srisonchai.

Tak Province, Umphang District: 15 males, 13 females, 1 male missing right gonopod, 1 male missing left gonopod, 4 males missing gonopods (CUMZ), Tham Takhobi (Takhobi Cave), 16°03'15"N, 98°49'14"E, ca. 511 m a.s.l., 5 July 2009, leg. S. Panha and ASRU members. 7 males, 11 females (CUMZ), Tham Takhobi (Takhobi Cave), 16°03'15"N, 98°49'14"E, ca. 511 m a.s.l., 5 July 2009, leg. S. Panha and ASRU members. 2 males, 5 females, 1 male missing right gonopod, 8 males missing gonopods, 2 broken males, many broken and mixed specimens (CUMZ), Doi Hua Mod, 15°57'30"N, 98°51'13"E, ca. 893 m a.s.l., 5 July 2009, leg. S. Panha and ASRU members. 6 males, 7 females (CUMZ) Doi Hua Mod, 15°57'30"N, 98°51'13"E, ca. 893 m a.s.l., 1 July 2015, leg. S. Panha and ASRU members. 1 male, 1 female (CUMZ), Mae Klong Kee Bureau of Monks, 16°13'46"N, 98°55'12"E, ca. 586 m a.s.l., 5 July 2009, leg. C. Sutcharit, R. Srisonchai, and ASRU members. 1 male, 1 female (CUMZ), Ban Ta Per Pru - Wa Krue Kro, 16°10'49"N, 98°52'48"E, ca. 523 m a.s.l., 30 June 2015, leg. C. Sutcharit, R. Srisonchai, and ASRU members. 29 males, 47 females, 5 broken males, 4 broken females; 1 male missing gonopods, 1 broken male and missing gonopods, 1 male remaining rings 7-20, 1 female remaining rings 1-10 (CUMZ), Km 162 on road no.1090 from Mae Sot to Umphang (near Chao Por Phawo Shrine Umphang), 16°02'23"N, 98°50'60"E, ca. 483 m a.s.l., 6 July 2009, leg. S. Panha and ASRU members. 3 males, 7 females, 1 juvenile (CUMZ), Ban Ta Per Pru - Wa Krue Kro Village, 16°10'49"N, 98°52'48"E, ca. 523 m a.s.l., 30 June 2015, leg. C. Sutcharit and ASRU members. 3 males, 1 female, 4 juveniles (CUMZ), Ban Kra Per Pru, 16°12'15"N, 98°52'04"E, ca. 628 m a.s.l., 2 July 2015, leg. C. Sutcharit and ASRU members.

Type locality.

THAILAND, Tak Province, Phobphra District, Nangkruen Waterfall.

Diagnosis.

Differs from all other Desmoxytes species by the combination of the following characters; lamina lateralis (ll) subtriangular; ventral lobe (vll) of lamina lateralis thumb-like, large and long; broad lobe (blm) of lamina medialis indistinctly demarcated from distal lobe (dlm) of lamina medialis by very shallow or slightly deep indentation.

Redescription (updated from Srisonchai et al. 2016).

SIZE: Population A (see Remarks): Length 24-26 mm (male), 25-27 mm (female); width of midbody metazona ca. 1.9 mm (male), 2.2 mm (female). Width of head = collum = body ring 2 = 3 = 4 <5 <6-16, thereafter body gradually tapering toward telson. Population B (see Remarks): Length 29-31 mm (male), 32-35 mm (female); width of midbody metazona ca. 1.9 mm (male), 2.3 mm (female). Width of head <collum> body ring 2> 3> 4 <5-16, thereafter body gradually tapering toward telson.

COLOUR (Fig. 82 A–D): Population A (see below): In life with body bright red; paraterga, metaterga and surface below paraterga red; head, antennae (distal part of antennomere 7 and antennomere 8 whitish), a few basal podomeres, sterna and epiproct brownish red. Population B (see below): In life with body bright pink; paraterga, metaterga and surface below paraterga bright pink; head brown; antenna blackish brown (except distal part of antennomere 7 and antennomere 8 whitish); legs brownish pink to brown; a few basal podomeres pale brown to whitish; sterna and epiproct brownish pink. Colour in alcohol: after one year changed to pale brown or almost whitish in some specimens.

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

COLLUM: With 3 transverse rows of setiferous tubercles, 4+4 anterior, 1+1 intermediate and 2+2 posterior tubercles (lateral tubercles of posterior row located almost halfway to intermediate row); paraterga of collum low, elevated at ca. 10°-15°, directed caudolaterad, with one distinct notch on lateral margin.

TEGUMENT: Slightly shining; collum and metaterga coarsely microgranulate; prozona finely shagreened; surface below paraterga finely microgranulate; paraterga, sterna and epiproct smooth.

METATERGA: With 2 transverse rows of setae, setiferous tubercles and setiferous spines; metaterga 2-8 with 2+2 anterior and 2+2 posterior spines; metaterga 9-17 with 2+2 anterior and 3+3 posterior spines; metatergum 18 with 2+2 anterior spines and 3+3 posterior tubercles; metatergum 19 with 2+2 anterior and 3+3 posterior setae or tubercles.

PARATERGA: Directed caudolaterad on body rings 2-17, elevated at ca. 45° (male) 40° (female); directed increasingly caudad on body rings 18 and 19; anterior margin with 2 distinct notches, on lateral margin of body rings 9, 10, 12, 13, 15-18 with tiny denticle near the tip.

TELSON: Epiproct: tip subtruncate; lateral setiferous tubercles conspicuous, short; apical tubercles inconspicuous. Hypoproct subsemicircular (population B subtrapeziform); caudal margin round, with inconspicuous setiferous tubercles.

STERNA: Cross-impressions shallow. Sternal lobe between male coxae 4 swollen, subtrapeziform when seen in caudal view; base enlarged, slightly attenuated near tip; tip round (in population B subtruncate).

LEGS: Very long and slender. Male femora 5 and 6 strongly humped ventrally in middle part.

GONOPODS (Fig. 83): Coxa (cx) longer than prefemur. Cannula (ca) slender. Prefemur (pfe) ca. 2/3 as long as femur. Femur (fe) long and slender. Mesal sulcus (ms) and lateral sulcus (ls) very deep and wide. Postfemur (pof) conspicuous, ventrally wide. Solenophore (sph) well-developed: lamina lateralis (ll) swollen, like a triangular lobe when seen in lateral view; ventral lobe (vll) thumb-like, large (in population B thumb-like, longer and more slender than in population A), directed ventrad: lamina medialis (lm) well-developed; process (plm) long, directed mesad, tip usually sharp (in some specimens almost blunt); distal lobe (dlm) well-developed, distally with one broad and thin lamella (in population B distally with two lamellae; mesal lamella very small, crest-like; lateral lamella broad and thin, in situ terminating close to tip of solenomere); broad lobe (blm) thick, indistinctly demarcated from distal lobe (dlm) by a usually wide and shallow indentation (in some specimens demarcated from distal lobe (dlm) by a deep indentation). Solenomere (sl) quite long.

Distribution and habitat.

Known only from Tak and Kamphaeng Phet Provinces. This species is restricted to limestone habitats and was seen crawling on litter and decaying bark (Fig. 82F). Srisonchai et al. (2016) reported that D. takensis was found on humid plastic garbage, a sign that the type locality is clearly under human influence. There is a long, broad concrete natural trail into the waterfall, and lots of garbage littered the type locality. However, the species has also been found in other natural habitats.

During our intensive surveys in western Thailand, we found this species in many places. However, it has a narrow range and occurs in only two provinces. Thus, D. takensis should be regarded to be endemic to the Thai fauna.

Remarks.

Based on morphology, we divided our material specimens into two main populations: Population A includes specimens from Nangkruen Waterfall (type locality), Tham Takhobi, Doi Hua Mod, Mae Klong Kee Bureau of Monks, Ban Ta Per Pru - Wa Krue Kro, Km 162 on road no.1090 near Chao Por Phawo Shrine Umphang and Ban Kra Per Pru. Population B includes specimens from Khlong Lan Waterfall, Km 89 on road no. 105 from Mae Sot to Mae Hong Son, Km 131 on road no. 105 from Mae Sot to Mae Hong Son, Chao Por Phawo Shrine (Mae Sot), Wat Tham Inthanin and Wat Pho Thi Khun.

The two populations differ in some characters as follows:

- Colour: The remarkable body colour of the two populations apparently differs: bright red in population A, vivid pink in population B (some old females strongly pinkish to reddish).

- Size: Population B individuals seem to be bigger than population A ones in both width and length (see size description).

- Hypoproct: The shape of the hypoproct in population A is subsemicircular whereas it is subtrapeziform in population B.

- Gonopods: The ventral lobe (vll) of lamina lateralis of population B specimens is large, thumb-like, longer, and more slender than that of population A ones. The distal lobe (dlm) of lamina medialis in population A specimens consists of one lamella while population B specimens have two lamellae distally.

Although the two populations vary in some morphological characters, they show an overall gonopodal resemblance. According to the differences in morphology of the two populations, this might an example of ongoing speciation in allopatry, supported by the confinement of the two populations to two large isolated limestone regions located in the northern (Population B) and southern (Population A) parts of the distribution area.

We collected some juveniles during the field trip and kept them with litter until they moulted. Interestingly, the juveniles made a moulting chamber which was apparently produced by fecal material and silk; it is probable that the building process is the same as in the families Polydesmidae , Pyrgodesmidae and in order Callipodida ( Adis et al. 2000, Youngsteadt 2009, Reboleira and Enghoff 2016). This is the first observation of moulting in dragon millipedes; however, we did not keep an eye on them in detail. After moulting and emerging from the chamber, the specimens were in an early adult stage showing a pale whitish colouration. Nearly 2 weeks later, they became vivid pink (Fig. 82D, E).

Coexisting species.

None known.

Corrections to Srisonchai et al. (2016)

Srisonchai et al. (2016: 99-103) wrote in the description of this species that the paraterga (including paraterga of collum) are directed dorsolaterad at ca. 30°. They are in fact directed caudolaterad and are elevated at ca. as 45°.