Desmoxytes terae (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 terae (Jeekel, 1964) Figs 88, 89, 90, 91, 92

Pratinus terae Jeekel, 1964: 69; 1968: 51.

Pteroxytes terae - Jeekel 1980a: 655.

Desmoxytes terae - Golovatch and Enghoff 1994: 59. Enghoff 2005: 97. Nguyen and Sierwald 2013: 1243.

Material examined.

Holotype. Male (NBC), MALAYSIA, Perlis, Kaki Bukit, near Kampong Wang Tangga, 19 December 1958, leg. W.S.S van der Feen-van Benthem Jutting.

Paratypes. 1 female, 1 female fragment (NBC), same data as holotype.

Further specimens, all from THAILAND, Satun Province:

1 male (ZMUC), Thale Ban National Park, in logs, litter, under stones, 6°42'N, 100°10'E, 8 November 1990, leg. M. Andersen and A. R. Rasmussen. 1 female (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., 31 August 2015, leg. S. Sutcharit, A. Pholyotha, T. Seesamut, and R. Srisonchai. 2 males, 6 females (CUMZ), 1 female (ZMUC), 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.

Diagnosis.

Differs from all other Desmoxytes species by the combination of the following characters; body black or brownish black contrasting with yellowish white paraterga with a triangular dorsal, dark spot; sternal lobe between male coxae 4 short and stout, broad at base, trapeziform or semicircular; male femora 5 and 6 without modification; lamina lateralis (ll) with big and long lobe-like structure projecting ventroanteriad.

Type locality.

MALAYSIA, Perlis, Kaki Bukit, near Kampong Wang Tangga.

The redescription hereunder is modified from Jeekel (1964); we ‘harmonised’ descriptions of all morphological characters and added some morphological characteristics from additional specimens.

Redescription.

SIZE: Length 28-32 mm (male), 28-34 mm (female); width of midbody metazona ca. 2.4 mm (male), 3.1 mm (female). Width of head <collum ≤ body ring 2 ≤ 3 = 4 <5-17, thereafter body gradually tapering toward telson.

COLOUR (Fig. 88A, B): In life with body black or brownish black; paraterga yellowish white (dorsal side with triangular dark brown spot); metaterga, surface below paraterga and prozona black or brownish black; head black; antenna brownish black (except distal part of antennomere 7 and antennomere 8 whitish); legs brown; sterna brown to yellowish brown; a few basal podomeres and epiproct pale brown. Colour in alcohol: after 49 years changed to whitish brown, 2-5 years changed to pale blackish brown.

ANTENNAE (Fig. 89D): Long and slender, reaching to body ring 6 (male), and 5 (female) when stretched dorsally.

COLLUM (Fig. 89A): With 3 transverse rows of setae and tubercles, 3+3 anterior setae, 1+1 intermediate tubercles and 2+2 posterior tubercles (tubercles small, without setae), lateral tubercles of posterior row located more anteriorly, almost halfway to intermediate row; paraterga of collum with two distinct setiferous notches on lateral margin, directed caudolaterad, almost horizontal.

TEGUMENT: Quite dull, sometimes shining; collum coarsely microgranulate; prozona, metaterga and surface below paraterga finely microgranulate; paraterga smooth (dorsal side finely microgranulate); sterna and epiproct smooth.

METATERGA (Fig. 89 A–C): With 2 transverse rows of tubercles; metaterga 2-19 with 2+2 anterior and 2+2 posterior tubercles.

PARATERGA (Fig. 89E, F): Directed caudolaterad on body rings 2-17, elevated ca. 5°-10° above the horizontal plane in both sexes; 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 very small and tiny denticle near the tip.

TELSON (Fig. 90 C–G): Epiproct: tip usually subtruncate (in some specimens slightly emarginate); lateral setiferous tubercles usually conspicuous (in some specimens inconspicuous), quite short; apical tubercles inconspicuous. Hypoproct trapeziform; caudal margin usually subtruncate (in some specimens slightly round), with big and conspicuous setiferous tubercles.

STERNA (Fig. 91): Cross-impressions quite deep. Sternal lobe between male coxae 4 swollen, short and stout, broad at base, usually trapeziform (in some specimens semicircular), tip usually truncate (in some specimens round).

LEGS (Fig. 90 H–J): Long and slender. Male femora 5 and 6 without modification.

GONOPODS (Fig. 92): Coxa (cx) longer than prefemur. Cannula (ca) slender. Prefemur (pfe) ca. 2/3 as long as femur, quite short and stout. Femur (fe) long and slender. Mesal sulcus (ms) and lateral sulcus (ls) deep. Postfemur (pof) conspicuous, ventrally wide. Solenophore (sph) well-developed: lamina lateralis (ll) swollen, with a big and long lobe-like structure projecting ventroanteriad: lamina medialis (lm) well-developed, longer than lamina lateralis; process (plm) short; distal lobe (dlm) quite broad, distally with two lamellae (mesal lamella shorter than lateral one); broad lobe (blm) long and thick, obviously demarcated from distal lobe (dlm) by a slightly deep and wide indentation. Solenomere (sl) very long.

Distribution and habitat.

This species is known only from the Malaysia–Thailand borderland (Kaki Bukit and Thale Ban National Park). We noticed that it prefers to live on humid mosses, logs or litter in limestone habitats (Fig. 88C). The localities are all on limestone mountains. The species is probably distributed in a narrow range in limestone areas near the Thai–Malay border. D. terae has so far been recorded from three localities (near Kaki Bukit, Thale Ban National Park, and Tham Tone Din) which are located only 10-15 km apart. Despite several attempts by us, D. terae was not found in other areas. Hence, this species should be regarded as endemic to the Malaysia and Thailand faunas.

Remarks.

In the recent field surveys we noticed that the colour of living specimens is black or brownish black with contrasting white paraterga as reported earlier by Jeekel (1964) and Golovatch and Enghoff (1994). This species blends so perfectly with its environment that it is difficult to collect specimens without a flashlight.

In the original description, Jeekel (1964) stated about the collum: "near the anterior margin a transverse row of six hairs, which may be present partly rubbed off, the lateral pair placed on the low tubercles". This means collum with one row of 3+3 anterior setae/tubercles. Moreover, Jeekel also described paraterga without a tiny denticle near the tip. After we examined all specimens, it is clear that:

- Collum with 3 rows of 3+3 anterior setae, 1+1 intermediate tubercles and 2+2 posterior tubercles (tubercles without setae, quite small but conspicuous).

- Paraterga of body rings 9, 10, 12, 13, 15-18 with tiny denticle near ther tip, albeit all quite small.

The sternal lobe between male coxae 4 shows some variation within populations; the lobe of some specimens is trapeziform whereas in others it is semicircular. We also found some variability on the telson: tip of epiproct subtruncate in some individuals, in others slightly emarginate; lateral setiferous tubercles conspicuous in some specimens, inconspicuous in others; caudal margin of hypoproct truncate in some individuals, slightly round in others.

Coexisting species.

This species and D. delfae are sympatric at Tam Ton Din.