Desmoxytes euros Srisonchai, Enghoff & Panha

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 euros Srisonchai, Enghoff & Panha sp. n. Figs 37, 38, 39, 40, 41, 42

Holotype.

Male (CUMZ), THAILAND, Chanthaburi Province, Kaeng Hang Maeo District, Khao Wong Kot Cave, 12°53'53"N, 101°49'00"E, ca. 53 m a.s.l., 4 August 2016, leg. S. Panha, P. Tongkerd ans ASRU members.

Paratypes.

13 males, 5 females (CUMZ), same data as holotype. 3 males, 4 females (CUMZ), 2 males, 1 female (ZMUC), 1 male (NHMW), THALAND, Rayong Province, Khao Chamao District, Wat Tham Suwan Phupha, 12°59'16"N, 101°39'32"E, ca. 64 m a.s.l., 8 August 2017, leg. P. Tongkerd and ASRU members.

Further specimens,

not paratypes, all from THAILAND, Chantaburi Province: 1 male, 1 female (CUMZ), Kaeng Hang Maeo District, Khao Wong Kot Cave, 12°53'53"N, 101°49'00"E, ca. 53 m a.s.l., 15 September 2009, leg. S. Panha and ASRU members. 1 male, 1 female (CUMZ), Kaeng Hang Maeo District, Khao Wong Kot Cave, 12°53'53"N, 101°49'00"E, ca. 53 m a.s.l., 1 October 2009, leg. S. Panha and ASRU members. 2 males, 1 female (CUMZ), Kaeng Hang Maeo District, near Khao Wong Kot Cave, 12°53'53"N, 101°49'00"E, ca. 53 m a.s.l., 15 October 2010, leg. S. Panha and ASRU members. 1 male, 2 females (CUMZ), Kaeng Hang Maeo District, near Khao Wong Kot Cave, 12°53'53"N, 101°49'00"E, ca. 53 m a.s.l., 24 October 2010, leg. S. Panha and ASRU members. 4 males, 4 females, 2 juveniles (CUMZ), Kaeng Hang Maeo District, Khao Wong Kot Cave, 12°53'53"N, 101°49'00"E, ca. 53 m a.s.l., 17 October 2015, leg. C. Sutcharit and R. Srisonchai. 1 female (CUMZ), Kaeng Hang Maeo District, Khao Wong Kot Cave, 12°53'53"N, 101°49'00"E, ca. 53 m a.s.l., 8 August 2017, leg. S. Panha, P. Tongkerd ans ASRU members. 5 males, 3 females (CUMZ), Kaeng Hang Maeo District, Khao Sip Ha Chan National Park, 13°10'33"N, 102°00'09"E, ca. 118 m a.s.l., 7 October 2010, leg. S. Panha and ASRU members. 2 males, 1 female (CUMZ), Khlung District, Makok Waterfall, 12°35'14"N, 102°15'21"E, ca. 58 m a.s.l., 3 September 2007, leg. ASRU members. 1 male, 1 female (CUMZ), Khlung District, Makok Waterfall, 12°35'14"N, 102°15'21"E, ca. 59 m a.s.l., 3 September 2007, leg. ASRU members. 3 males, 3 females, 4 females (CUMZ), Khlung District, Makok Waterfall, 12°35'14"N, 102°15'21"E, ca. 58 m a.s.l., 10 August 2014, leg. ASRU members. 5 males, 3 females (CUMZ), Mueang Chantaburi District, Phlio Waterfall, 12°31'44"N 102°10'57"E, ca. 104 m a.s.l., 19 October 2015, leg. S. Panha and ASRU members. 2 males, 2 females (CUMZ), Tha Mai District, Wat Khao Su Kim (Khao Su Kim Temple), 12°45'47"N, 102°01'56"E, ca. 148 m a.s.l., 29 September 2009, leg. S. Panha and ASRU members. 3 males, 5 females (CUMZ), Tha Mai District, Wat Khao Su Kim (Khao Su Kim Temple), 12°45'47"N, 102°01'56"E, ca. 148 m a.s.l., 14 October 2010, leg. S. Panha and ASRU members. 2 males, 2 females (CUMZ), Tha Mai District, Wat Khao Su Kim (Khao Su Kim Temple), 12°45'47"N, 102°01'56"E, ca. 148 m a.s.l., 6 August 2011, leg. S. Panha and ASRU members. 2 males, 1 female, 1 juvenile (CUMZ), Tha Mai District, Wat Khao Su Kim (Khao Su Kim Temple), 12°45'47"N, 102°01'56"E, ca. 148 m a.s.l., 8 August 2017, leg. S. Panha, P. Tongkerd and ASRU members.

Chonburi Province: 2 males, 3 females (CUMZ), Bo Thong District, Wat Tham Khao Cha-ang Oune, 13°12'35"N, 101°39'09"E, ca. 151 m a.s.l., 15 September 2009, leg. ASRU members. 2 males, 3 females (CUMZ), Bo Thong District, Wat Tham Khao Cha-ang Oune, 13°12'35"N, 101°39'09"E, ca. 151 m a.s.l., 15 October 2010, leg. ASRU members. 2 males (CUMZ), Bo Thong District, Wat Tham Khao Cha-ang Oune, 13°12'35"N, 101°39'09"E, ca. 151 m a.s.l., 24 September 2012, leg. S. Panha and ASRU members. 2 males, 2 females (CUMZ), Bo Thong District, Wat Tham Khao Cha-ang Oune, 13°12'35"N, 101°39'09"E, ca. 151 m a.s.l., 6 July 2016, leg. A. Pholyotha and ASRU members. 1 male, 1 female (CUMZ), Bo Thong District, Wat Tham Khao Cha-ang Oune, 13°12'35"N, 101°39'09"E, ca. 151 m a.s.l., 25 October, leg. ASRU members.

Rayong Province: 1 male, 1 female (CUMZ), Khao Chamao District, Wat Tham Watana Monkhol, 13°05'45"N, 101°36'28"E, ca. 76 m a.s.l., Unknown date, leg. S. Panha and ASRU members. 3 males (CUMZ), Khao Chamao District, Wat Tham Khao Loy (Wat Ma Duae), 13°03'26"N, 101°36'28"E, ca. 71 m a.s.l., 5 September 2008, leg. S. Panha and ASRU members. 1 male, 1 female (CUMZ), Khao Chamao District, Wat Tham Khao Loy (Wat Ma Duae), 13°03'26"N, 101°36'28"E, ca. 71 m a.s.l., 23 October 2010, leg. S. Panha and ASRU members. 1 male, 3 females (CUMZ), Khao Chamao District, Wat Tham Khao Loy (Wat Ma Duae), 13°03'26"N, 101°36'28"E, ca. 71 m a.s.l., 9 November 2013, leg. S. Panha and ASRU members. 1 male, 1 female (CUMZ), Khao Chamao District, Tham Khao Pratun Monastery, 13°07'26"N, 101°35'52"E, ca. 107 m a.s.l., 24 October 2010, leg. S. Panha and ASRU members. 1 male, 1 female (CUMZ), Khao Chamao District, Khlong Pra Kang Waterfall, 12°55'59"N, 101°42'58"E, ca. 69 m a.s.l., 15 September 2009, leg. S. Panha and ASRU members. 1 male, 1 female (CUMZ), Khao Chamao District, Tham Khao Boath Bureau of Monks, 13°02'13"N, 101°38'08"E, ca. 102 m a.s.l., 23 October 2010, leg. S. Panha and ASRU members. 2 males, 2 females (CUMZ), Khao Chamao District, Wat Nong Tha Khian, 12°57'49"N, 101°40'24"E, ca. 64 m a.s.l., 5 September 2008, leg. C. Sutcharit and ASRU members. 1 male, 1 female (CUMZ), Khao Chamao District, Wat Tham Khao Chamao, 23 October 2008, leg. C. Sutcharit and ASRU members.

Sa Kaeo Province: 1 male, 1 female (CUMZ), Khlong Hat District, Phet Pho Thong Cave, 13°24'50"N, 102°19'33"E, ca. 240 m a.s.l., 28 October 2010, leg. C. Sutcharit and ASRU members. 1 male, 1 female (CUMZ), Khao Chakan District, near Wat Tham Khao Chakan, 13°39'40"N, 102°05'11"E, ca. 75 m a.s.l., 28 August 2014, leg. S. Panha and ASRU members. 2 males, 1 female (CUMZ), Khlong Hat District, Phet Pho Thong Cave, 13°24'50"N, 102°19'33"E, ca. 240 m a.s.l., 28 August 2014, leg. S. Panha and ASRU members. 1 male, 3 females (CUMZ), Khao Chakan District, near Wat Tham Khao Chakan, 13°39'40"N, 102°05'11"E, ca. 75 m a.s.l., 3 September 2015, leg. S. Panha and ASRU members.

Diagnosis.

Body black or brownish black; collum with 3 transverse rows of setae and setiferous tubercles (4+4 anterior setae, 1+1 intermediate setae and 2+2 posterior tubercles); metaterga 2-16 with two rows of 2+2 (anterior) setiferous cones and 2+2 (posterior) setiferous spines; ventral ridge (vrl) of lamina lateralis conspicuous; process (plm) of lamina medialis long, directed almost mesad; distal lobe (dlm) distally with two distinct lamellae. Similar in these respects to D. planata , but differs from that species by having paraterga yellow to orange and hypoproct subtriangular with conspicuous setiferous tubercles.

Etymology.

“Euros” (noun in apposition) is the name of the ancient Greek god of the east wind; the name refers to the occurrence of this species in the eastern part of Thailand.

Description.

SIZE: Length 25-27 mm (male), 28-29 mm (female); width of midbody metazona ca. 1.6 mm (male), 2 mm (female). Width of head <collum = body ring 2 <3 = 4 <5-16, thereafter body gradually tapering towards telson.

COLOUR (Fig. 37 A–D): In life with body dark or brownish black; paraterga yellow to orange; head, antenna, metaterga and surface below paraterga dark brown (except distal part of antennomere 7 and antennomere 8 whitish); epiproct, sterna and a few basal podomeres brown to whitish; legs otherwise brown.

ANTENNAE (Fig. 38D): Moderately long and slender, reaching to body ring 6 (male) and 5 (female) when stretched dorsally.

COLLUM (Fig. 38A): With 3 transverse rows of setae and setiferous tubercles, 4+4 anterior setae, 1+1 intermediate setae and 2+2 posterior tubercles (lateral seta in anterior row located almost at base of paraterga in some specimens); paraterga of collum low, elevated at ca. 15°-20°, directed caudolaterad, with one inconspicuous notch on lateral margin.

TEGUMENT: Quite dull, slightly shining; collum and metaterga microgranulate; prozona finely shagreened; surface below paraterga finely microgranulate; sterna and epiproct smooth.

METATERGA (Fig. 38 A–C): With 2 transverse rows of setiferous tubercles, cones and spines; metaterga 2-8 with 2+2 anterior cones and 2+2 posterior spines; metaterga 9-16 with 2+2 anterior cones and 2+2 posterior spines; metaterga 17-18 with 2+2 anterior and 2+2 posterior cones; metatergum 19 with 2+2 anterior and 2+2 posterior tubercles.

PARATERGA (Fig. 38E, F): 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 (Fig. 39 C–G): Epiproct: tip emarginate; lateral setiferous tubercles and apical tubercles conspicuous. Hypoproct subtriangular; caudal margin subtriangular, with conspicuous setiferous tubercles.

STERNA (Fig. 40): Cross-impressions shallow. Sternal lobe between male coxae 4 swollen, base stout, slightly attenuated near tip, knob-like when seen in lateral view, tip subtruncate.

LEGS (Fig. 39 H–J): Long and slender. Male femora 5 and 6 moderately humped ventrally in middle portion.

GONOPODS (Figs 41, 42): Coxa (cx) longer than prefemur. Cannula (ca) long and slender. Prefemur (pfe) ca. 2/3 as long as femur. Femur (fe) long and slender. Mesal sulcus (ms) and lateral sulcus (ls) conspicuous, very deep. Postfemur (pof) conspicuous, ventrally narrow and short. Solenophore (sph) well-developed: lamina lateralis (ll) well-developed, inner surface subsided, anterolaterally with an inconspicuous furrow; with conspicuous ventral ridge (vrl): lamina medialis (lm) well-developed; process (plm) long, tip blunt, directed mesad; distal lobe (dlm) distally with two distinct lamellae (equal in size); broad lobe (blm) dorsally thick at the edge, with a wide and conspicuous indentation between broad lobe (blm) and distal lobe (dlm). Solenomere (sl) very long.

Distribution and habitat.

Known only from east Thailand (Chantaburi, Chonburi, Sa Kaeo and Rayong Provinces). Interestingly, this species exists in both limestone areas and granitic mountains. It was seen crawling on rocks during the rainy season and occurs only in natural habitat inside primary forest. On the basis of current data, the distribution area is quite narrow, and the species seems to be restricted to the eastern part of Thailand. We thus regard D. euros sp. n. to be an endemic for the Thai fauna.

Remarks.

The observation of all living specimens reveals variation on colour of paraterga within a population; yellow in some specimens, yellowish orange to orange in others.

Desmoxytes euros sp. n. strongly resembles D. planata in several morphological characters (except for the characters mentioned in the diagnosis); notably the gonopod characters are identical. However, our initial study on DNA barcoding gene (COI) revealed that D. planata and the new species are separated enough to support the suggestion that D. planata and the new species are indeed different species (paper in preparation).

Because of the similarity in gonopod morphology, it is difficult to discriminate old material of D. planata and D. euros sp. n. However, they can be distinguished by colour of paraterga (yellow or yellow orange in D. euros sp. n., pink in D. planata ), and by characters of hypoproct (subtriangular in D. euros sp. n., subtrapeziform in D. planata ).

We kept several adults in an acrylic box with litter at room temperature. Two weeks later, we found a nest with eggs and a cluster of stadium 1 juveniles at ca. 2 cm depth in the soil and leaf litter (Fig. 37E, F).

Coexisting species.

None known.