Desmoxytes delfae (Jeekel, 1964)

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 delfae (Jeekel, 1964) Figs 29, 30, 31, 32, 33, 34, 35

Pratinus delfae Jeekel, 1964: 66; 1968: 51.

Desmoxytes delfae Jeekel, 1980a: 654. Golovatch and Enghoff 1994: 61. Enghoff 2005: 96. Decker 2010: 28. Nguyen and Sierwald 2013: 1241.

Desmoxytes rubra Golovatch & Enghoff, 1994: 54, syn. n. Enghoff 2005: 96. Decker 2010: 30. Nguyen and Sierwald 2013: 1242.

Material examined.

Holotype. Male (NHMUK), THAILAND, Bukit Besar, on leaves in clearing, late evening, 3 September 1901.

Paratypes.

1 male, 1 female (NHMUK), 1 male (NBC), THAILAND, Bukit Besar, Nawnchila, crawling on low foliage in clearing, 2500 feet a.s.l., 29 September 1901.

Holotype ( D. rubra ): Male (ZMUC), THAILAND, Satun Province, Thale Ban National Park, lowland rainforest, on vegetation and under bark, 6°42'N, 100°10'E, ca. 400 m a.s.l., 20 October 1991, leg. M. Andersen, O. Martin, N. Scharff.

Paratypes ( D. rubra ): 6 males, 5 females (ZMUC), same data as holotype.

Further specimens,

all from THAILAND, Krabi Province: 1 female (CUMZ), Mueang Krabi District, Huai To Waterfall, 8°14'27"N, 98°54'51"E, ca. 110 m a.s.l., 16 January 2006, leg. S. Panha and ASRU members. 1 male missing right gonopod (CUMZ), Mueang Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8°07'39"N, 98°55'27"E, ca. 85 m a.s.l., 7 October 2009, leg. S. Panha and ASRU members. 1 male (CUMZ), Mueang Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8°07'39"N, 98°55'27"E, ca. 85 m a.s.l., 28 April 2014, leg. C. Sutcharit, R. Srisonchai and ASRU members. 5 males, 2 females (CUMZ), Mueang Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8°07'39"N, 98°55'27"E, ca. 85 m a.s.l., 9 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members. 1 male, 1 female (CUMZ), Mueang Krabi District, Wat Tham Sue (Tiger Cave), valley behind Tiger Cave, 8°07'39"N, 98°55'27"E, ca. 85 m a.s.l., 25 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members.

Nakhon Si Thammarat Province: 2 broken males (CUMZ), Nopphitam District, Krung Ching Waterfall, 8°43'27"N, 99°40'07"E, ca. 171 m a.s.l., 28 October 2006, leg. S. Panha and ASRU members. 1 female (CUMZ), Thung Song District, Talod Cave Park (Talod Cave), 8°09'32"N, 99°40'42"E, ca. 73 m a.s.l., 5 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members. 2 males, 1 female (CUMZ), Thung Song District, Weruwan Bureau of Monks (Tham Rad), 8°02'48"N, 99°43'43"E, ca. 82 m a.s.l., 5 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members.

Phatthalung Province: 2 males,1 female (CUMZ), Khao Chaison District, Khao Chaison Hot Spring, 7°26'59"N, 100°07'48"E, ca. 37 m a.s.l., 12 January 2009, leg. S. Panha and ASRU members. 1 broken male missing gonopods, 2 females (CUMZ), Khao Chaison District, Khao Chaison Hot Spring, 7°26'59"N, 100°07'48"E, ca. 37 m a.s.l., 13 January 2009, leg. C. Sutcharit and ASRU members. 1 female (CUMZ), Khuan Khanun District, Tham Wang Thong, 7°40'57"N, 100°00'58"E, ca. 45 m a.s.l., 12 January 2009, leg. C. Sutcharit and ASRU members. 3 males, 1 female (CUMZ), Khuan Khanun District, Tham Wang Thong, 7°40'57"N, 100°00'58"E, ca. 45 m a.s.l., 6 July 2017, leg. C. Sutcharit and ASRU members. 3 males, 3 females (CUMZ), Kong Ra District, Khao Phaya Hong, 7°27'46"N, 99°57'50"E, ca. 55 m a.s.l., 6 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members.

Satun Province: 1 male (ZMUC), Thale Ban National Park, lowland rainforest, 6°42'37"N, 100°10'09"E, ca. 93 m a.s.l., 15-18 October 2003, leg. ATOL expedition (ZMUC staff). 7 males, 2 females (CUMZ), Thung Wa District, Tham Khan Ti Phol, 7°05'11"N, 99°47'53"E, ca. 82 m a.s.l., 8 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members. 26 males, 4 females (CUMZ), 2 males, 1 female (ZMUC), 1 male (ZMUM), 1 male (NHMW),1 male (NHMUK), Thung Wa District, Tham Khan Ti Phol, 7°05'11"N, 99°47'53"E, ca. 82 m a.s.l., 7 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members. 2 males, 2 females (CUMZ), Khuan Don District, Thale Ban National Park, Tham Tone Din (Tone Din Cave), 6°43'35"N, 100°09'45"E, ca. 154 m a.s.l., 7 July 2017, leg. S. Sutcharit, R. Srisonchai and ASRU members. 1 female (CUMZ), La-ngu District, limestone mountain near Ao Noon (Mu Ko Petra National Park), 6°50'17"N, 99°45'41"E, ca. 37 m a.s.l., 31 August 2015, leg. C. Sutcharit, R. Srisonchai and ASRU members. 2 males (CUMZ), La-ngu District, limestone mountain near La-ngu Subdistrict, 6°53'41"N, 99°46'49"E, ca. 18 m a.s.l., 17 July 2017, leg. P. Danaisawadi.

Songkhla Province: 1 male missing gonopods (CUMZ), Hat Yai District, Ton Nga Chang Waterfall, 6°56'53"N, 100°14'03"E, ca. 157 m a.s.l., 12 January 2009, leg. S. Panha and ASRU members. Many broken and mixed specimens (CUMZ), Hat Yai District, Ton Nga Chang Waterfall, 6°56'53"N, 100°14'03"E, ca. 157 m a.s.l., 13 December 2011, leg. S. Panha and ASRU members. 4 males, 4 females (CUMZ), Sa Dao District, Khao Wong Pra Chan Bureau of Monks, 6°42'38"N, 100°16'34"E, ca. 100 m a.s.l., 7-8 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members. 2 females (CUMZ), Sa Dao District, Tham Nang Phaya Lued Kao Bureau of Monks, 6°44'26"N, 100°15'27"E, ca. 124 m a.s.l., 7 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members.

Surat Thani Province: 2 males, 1 female (CUMZ), Wiang Sa District, Khiri Rat Pattana Bureau of Monks (Wat Khao Poon), 8°31'38"N, 99°22'59"E, ca. 49 m a.s.l., 4 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members. 2 males, 1 female (CUMZ), Tham Phannara District, Wat Tham Kanlaya Namit, 8°30'49"N, 99°22'53"E, ca. 62 m a.s.l., 4 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members.

Trang Province: 3 males, 3 females, 2 juveniles (CUMZ), Palian District, Tham Khao Ting, 7°09'31"N, 99°48'10"E, ca. 42 m a.s.l., 31 August 2015, leg. C. Sutcharit, R. Srisonchai and ASRU members. 9 males, 2 females (CUMZ), Palian District, Tham Khao Ting, 7°09'31"N, 99°48'10"E, ca. 42 m a.s.l., 8 July 2017, leg. C. Sutcharit, R. Srisonchai and ASRU members.

Yala Province: 1 male (ZMUC), Bang Lang National Park, lowland rainforest, 6°4'N, 101°11'E, ca. 400 m a.s.l., 20 October 1991, leg. M. Andersen, O. Martin, N. Scharff.

Diagnosis.

Differs from congeners in the combination of the following characters; sternal lobe between male coxae 4 thick and stout, round/ subtrapeziform/ subrectangular; lamina lateralis (ll) swollen, round crest-like, laterally with a distinct and wide furrow, mesally with deep subsided surface; process (plm) of lamina medialis short, distally curving dorsad, tip blunt.

Type locality.

Thailand, Bukit Besar [Thale Ban National Park, Khuan Don District, Satun Province].

The redescription hereunder is modified from Jeekel (1964), and Golovatch and Enghoff (1994). We ‘harmonised’ descriptions of all morphological characters and added some morphological characteristics from additional collected specimens.

Redescription.

SIZE: Length 21-24 mm (male), 23-27 mm (female); width of midbody metazona ca. 1.8 mm (male), 2.3 mm (female). Width of head ≥ collum <body ring 2 <3 <4 <5-16, thereafter body gradually tapering towards telson.

COLOUR (Figs 29, 30 A–C): In life body bright orange or brownish orange (newly moulted adults pale pink); head, paraterga, surface below paraterga and epiproct yellowish orange; metaterga bright orange; antenna brownish orange or blackish orange (except antennomere 7 blackish, distal part of antennomere 7 and antennomere 8 whitish); legs brownish orange or brownish black; a few basal podomeres whitish yellow; sterna whitish yellow or orange; prozona and metazona (metaterga) with wide black stripe, conspicuous on rings 4-19. Colour in alcohol: after 116 years changed to white, after 26 years changed to brownish white.

ANTENNAE (Fig. 31D): Moderately long and slender, reaching to body ring 6 (male) and 4-5 (female) when stretched dorsally.

COLLUM (Fig. 31A): With 1 transverse anterior row of 3+3 setae; paraterga of collum low, almost horizontal, directed almost caudad, with two setiferous notches on lateral margin.

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

METATERGA (Fig. 31 A–C): With 2 transverse rows of small tubercles; metaterga 2-19 with 2+2 anterior and 2+2 posterior tubercles.

PARATERGA (Fig. 31E, F): Directed caudolaterad on body rings 2-17, elevated ca. 10°-20° above the horizontal plane (ca. 20° in male, ca. 10° in 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. 32 C–G): Epiproct: tip truncate; lateral setiferous tubercles usually conspicuous (in some specimens inconspicuous); apical tubercles inconspicuous. Hypoproct subtriangular; caudal margin round and narrow, with inconspicuous setiferous tubercles.

STERNA (Fig. 33): Cross-impressions shallow. Sternal lobe between male coxae 4 round/ subtrapeziform/ subrectangular (varies within population); erect, stout, thick, and broad when seen in ventral view; tip subtruncate/ round/ emarginate (varies within population).

LEGS (Fig. 32 H–J): Long and slender. Male femora 5 and 6 strongly humped ventrally in middle portion.

GONOPODS (Figs 34, 35): Coxa (cx) longer than prefemur. Cannula (ca) long and slender. Prefemur (pfe) ca. 2/3 as long as femur. Femur (fe) quite long. Mesal sulcus (ms) and lateral sulcus (ls) conspicuous, deep and wide. Postfemur (pof) conspicuous, ventrally narrow, and short. Solenophore (sph) well-developed: lamina lateralis (ll) swollen, round crest-like, laterally with a distinct furrow, mesally with deep subsided surface; ventral ridge (vrl) conspicuous: lamina medialis (lm) well-developed; process (plm) short, distally curving dorsad, tip blunt; distal lobe (dlm) distally with two lamellae, mesal lamella thin and smaller than lateral one; broad lobe (blm) somewhat thick, distinctly separated from distal lobe (dlm) by a deep and wide indentation. Solenomere (sl) long.

Distribution and habitat.

Desmoxytes delfae is known from several provinces in southern Thailand. All new specimens were collected by us from limestone habitats (the recorded locations in previous papers are also limestone); most specimens were seen crawling on leaf litter and climbing on branches of trees (Fig. 30D).

The type locality, Bukit Besar, may be part of what is now Thale Ban National Park in Khuan Don District, Satun Province, and refers to the big mountain which is probably Khao Chin (ca. 2500 ft. or 756 m). Specimens collected by us from Thale Ban National Park may thus be topotypes. The other paratype locality (Bukit Besar, Nawnchila) has not been exactly located, but it is probably near Thale Ban National Park ( Thailand–Malaysia border), possibly close to the type locality.

We assume that D. delfae is distributed mainly in Thailand and possibly south to Malaysia near the Thailand–Malaysia border.

This species was reported as endemic for Thailand ( Decker 2010), and we would agree that it should be regarded as endemic for the southern part of Thailand due to its narrow distribution. However, two males of D. delfae were reported from Khaosok National Park in west of Surat Thani Province by Decker (2010); it is probable that the specimens from this location belong to another species because all the specimens of D. delfae which we have seen are from an area in south Thailand (Krabi, east of Surat Thaini, Nakhon Si Thammarat, Phatthalung, Satun, Songkhla, and Yala Provinces). Furthermore, Decker (2010) also identified one male, which was collected from Nakhon Si Thammarat Province (Lan Saka District, Khao Luang National Park, near Karom Waterfall) as D. rubra . Re-examination of those specimens in MHNG is necessary to evaluate the distribution of this species.

Remarks.

The remarkable and vivid bright orange colouration is clearly aposematic.

Golovatch and Enghoff (1994) distinguished D. rubra from D. delfae based on D. rubra having 1+1 anterior and 2+2 posterior metatergal tubercles, the mid-dorsal (axial) line traceable, the sternal lobe between male coxae 4 roundly subtriangular and lamina medialis (lm) more strongly produced mesally than dorsally. After examination of all type material and new specimens of both D. delfae and " D. rubra " collected by us, we found that:

- There is a variation in the size of tubercles on metaterga (metaterga with two rows of 2+2 anterior and 2+2 posterior tubercles, lateral tubercles of anterior row in some specimens (tiny and very inconspicuous).

- All specimens are without mid-dorsal line.

- The sternal lobe between male coxae 4 is highly variable in shape, even within populations, as round/ subtrapeziform/ subrectangular; we found this variation in both D. delfae and " D. rubra " specimens. Its tip also varies as subtruncate/ round/ emarginate.

- SEM images clearly show that specimens of these two nominal species have identical gonopods, especially in details of lamina lateralis and lamina medialis.

Due to this variation, we have synonymised D. rubra under D. delfae .

Jeekel (1964) described this species as lacking a tiny denticle near the tip of paraterga on the lateral margin of rings 9, 10, 12, 13, 15-18, and collum as having 2 rows of 3+3 conspicuous setae (anterior row) and 1?+1? inconspicuous tubercles (posterior row). All specimens studied by us have a tiny denticle near the tip (conspicuous in some specimens, inconspicuous in others), and we regard this character as variable within populations.

For D. rubra , Golovatch and Enghoff (1994) described the colour of alcohol-preserved specimens as bright pinkish, that of living specimens as bright red, collum with 3 rows of setae (anterior conspicuous, intermediate and posterior inconspicuous), mid-dorsal line traceable. Based on the re-examination of type material of D. rubra and examination of newly collected specimens we have found that D. rubra (= D. delfae ) exhibits:

- Specimens in life with bright orange colouration, newly moulted adult stage pinkish or pinkish orange, late adult stage reddish orange or dark orange. As Golovatch and Enghoff (1994) reported that living specimens have a bright red colour, it is possible that the type specimens of D. rubra were collected at late adult stage (red = reddish orange?).

- Collum with one row of setae (3+3 anterior setae), intermediate and posterior rows absent. Therefore, we here report collum with only one row of setae (3+3 anterior setae).

- All specimens without mid-dorsal line.

- Sternal lobe between male coxae 4 varies within population, round/ subtrapeziform/ subrectangular.

As we mentioned above, this species shows high variability in morphology, e.g., colour, rows of setae on collum, size of metatergal tubercles, occurrence of a tiny denticle near tip of paraterga, shape of sternal lobe between male coxae 4. All variations are typically present within a population. Although there are deviations in several morphological characters, interestingly, gonopod characters of all specimens are quite stable, looking exactly the same in details.

Coexisting species.

Desmoxytes cervina in several places, D. terae at Tham Tone Din, D. flabella sp. n. at Tham Khao Ting and Tham Khan Ti Phol.