Habitus. Body length 7–8.5 mm [10 mm, including antennae]. Most specimens with 31 leg-bearing segments, one female (NHMUK015991298) with 33. Colour in ethanol white.

Head and antennae (Fig. 1C, F; Fig. 2). Antennae 0.5–0.6 mm long, 2.4 times longer than cephalic capsule fully extended (Fig. 2A) [Fig. 1C]. Articles II and V with specialised sensillum microtrichodeum (type a sensu Pereira et al. (2000)) localised medially on the dorsal side (Fig. 2B). Articles IX and XIII with specialised sensillum basiconicum (type c sensu Pereira et al. (2000)) localised at distal edge on dorsal side (Fig. 2B). Starting from article VI, the distal antennal articles become moderately enlarged resulting in a mildly clavate general appearance (Fig. 2B) [Fig. 1C]. In ethanol, most specimens show weak geniculation of the antenna at article VI (Fig. 2B). Article XIV 1.5 times longer than wide with two groups of sensilla basiconica laterally and an apical group of small undivided hyaline sensilla (Fig. 2D). Cephalic plate nearly pentagonal, weakly narrowed posteriorly, about as long as broad, with generally uniform reticulation on dorsal side. Chaetotaxy as in Fig. 2C.

Figure 1.  

Mesoschendyla javanica (Attems, 1907). A, B Overview of slide-mounted syntypes in the NHMW collection; C NHMW-MY4883, cephalic capsule and antennae (ventral view); D NHMW-MY4883, clypeus and labrum with mandibles in situ (ventral view); E NHMW-MY4883, maxillae (lateral view); F NHMW-MY10655, cephalic capsule and antennae (dorsal view); G NHMW-MY10655, forcipular segment and anterior part of body (ventral view); H NHMW-MY10655, forcipules (ventral view); I NHMW-MY10655, anterior metasternite showing pore field (indicated by black arrow) (ventral view); J NHMW-MY10655, posterior part of body (ventral view).

Figure 2.  

Mesoschendyla javanica. A NHMUK015991355, head and anterior end of trunk (dorsal view); B NHMUK015991354, left antenna with specialised sensilla indicated (dorsal view); C NHMUK015991355, cephalic capsule (dorsal view); D NHMUK015991403, antennal article XIV (ventral view). a = sensillum microtrichodeum, c = sensillum basiconicum, h = undivided hyaline sensilla.

Clypeus (Fig. 1D; Fig. 3A). Inconspicuous reticulation across entire surface. One pair of postantennal and one pair of medial sensilla. Clypeal area and prelabral setae absent.

Figure 3.  

Mesoschendyla javanica. A NHMUK015991403, clypeus and labrum (ventral view); B NHMUK015991403, right mandible (dorsal view).

Labrum (Fig. 1D; Fig. 3A). Gently curved, bearing 9–12 tubercles [9 tubercles, Fig. 1D]. Medial tubercles with sclerotised rim apically. Lateral tubercles minute, medially recurved and apically tapering.

Mandible (Fig. 1D; Fig. 3B). With one single pectinate lamella and one dentate lamella. Dentate lamella bearing seven subequal curved tooth-like projections [six visible, Fig. 1D]. Projections of dentate lamella forming single contiguous row, not partitioned into blocks.

Maxillae (Fig. 1E; Fig. 4B, C). First maxillae without telopodital or coxosternal lappets. First maxillae with triangular coxosternal projections, each bearing one seta and uni-articulate telopodites, with one seta each (Fig. 4B). Second maxillary coxosternite with rounded, concave anterior margin. Telopodite short, robust, ending in claw-shaped pretarsus with pectinate lateral edges bearing gracile hyaline projections (Fig. 4C) [Fig. 1E]. Chaetotaxy as in Fig. 4B.

Figure 4.  

Mesoschendyla javanica. A NHMUK015991403, forcipular segment, sensillum coeloconicum indicated by black arrow (ventral view); B NHMUK015991403, maxillae (ventral view); C NHMUK015991403, article 3 and pretarsus of left second maxillary telopodite (ventral view).

Forcipular segment (Fig. 1G, H; Fig. 4A). Forcipular coxosternite 1.7 times broader than long (Fig. 4A) [Fig. 1G]. Chitin lines absent. Anterior margin broadly concave, lacking denticles or other projections. Forcipular trochanteroprefemur 1.1 times longer than broad, without denticles, but bearing one minute sensillum coeloconicum on internal side. Tarsungulum with basal bulge, but lacking basal denticle. Inner concavity with three broad, rectangular serrations. Calyx of venom gland visible in base of tarsungulum, ovoid. Chaetotaxy as in Fig. 4A.

Trunk (Fig. 1I; Fig. 5A–D). Anterior metasternites 2–12 with pore field comprising 4–10 pores localised postero-medially (Fig. 5A–D) [Fig. 1I]. No bulges or changes in cuticular structure observed around pore fields. Shape of pore fields anteriorly a posteriorly curved line, becoming an interrupted ovoid on metasternites 4–10 and transitioning again to a posteriorly curved line on metasternites 11–12. Chaetotaxy illustrated in Fig. 5A–D, comprising two internal rows of three macrosetae, two external rows of three macrosetae and two anteriorly recurved rows of microsetae at anterior margin. Walking legs with uniform chaetotaxy (Fig. 5E). Claw-shaped pretarsus with two basal accessory spines on the ventral side.

Figure 5.  

Mesoschendyla javanica. A NHMUK015991403, metasternite 2 (ventral view); B NHMUK015991403, metasternite 5 (ventral view); C NHMUK015991403, metasternite 8 (ventral view); D NHMUK015991403, metasternite 12 (ventral view); E NHMUK015991354, leg 30 (lateral view).

Last leg-bearing segment (Fig. 1J; Figs 6, 7, 8). Ultimate pleuropretergite whole (Fig. 6A). Ultimate metatergite trapezoidal, with straight posterior edge, 1.5x broader than long. Ultimate metasternite trapezoidal, 1.6–1.7 times broader than long in male (Fig. 6B) and 2x broader than long in female (Fig. 7A). Coxopleura moderately enlarged, with glandular mass opening in a single coxal organ, usually entirely covered by metasternite. In adult males, distal end of coxopleuron covered by dense field of setae (Fig. 6B). Ultimate leg telopodite of mature males densely setose ventrally and sparsely setose dorsally, with strongly enlarged trochanter, prefemur, femur and tibia and moderately enlarged tarsus and metatarsus; coxopleuron and telopodite more sparsely setose in small males (Fig. 8A). Metatarsus ending in minute hair-like projection in male (Fig. 6C–D) (frequently broken as in Fig. 8B); large, claw-shaped pretarsus in female (Fig. 7A). Male gonopods weakly biarticulate (articulation frequently inconspicuous), with distinct internal notch, flanking conical penis (Fig. 6B). Female gonopods uni-articulate, short, gently rounded and bearing one pair of setae (Fig. 7A). Anal pores present in both sexes, but frequently covered by genital segments in males.

Figure 6.  

Mesoschendyla javanica. A NHMUK015991355, male ultimate leg-bearing segment (dorsal view); B NHMUK015991355, male ultimate leg-bearing segment (ventral view); C, D NHMUK015991354, ultimate leg metatarsus of male (lateral views).

Figure 7.  

Mesoschendyla javanica. A NHMUK015991354, female ultimate leg-bearing segment (ventral view); B NHMUK015991352, male ultimate leg-bearing segment, setae not illustrated (ventral view).

Figure 8.  

Mesoschendyla javanica. A NHMUK015991403, male ultimate leg-bearing segment (ventral view); B NHMUK015991403, ultimate leg metatarsus of male (ventral view).

Body length 7–8.5 mm. 31–33 leg-bearing segments. Antennae weakly clavate and geniculate starting from article VI. Clypeus with one pair of postantennal and one pair of medial setae. Labrum with 9–12 tubercles. First maxillae lacking telopodital or coxosternal lappets. Tarsungulum with three broad, rectangular serrations along its inner concavity. Trunk metasternites 2–12 with pore field transitioning from single posteriorly curved row of pores to open ellipsoid shape and back to single posteriorly curved row of pores. Female ultimate leg telopodite with large claw-shaped pretarsus. Ultimate leg telopodite strongly sexually dimorphic; inflated and lacking pretarsus in male.

West Java (Bogor Regency, Indonesia) and northern Borneo (Sarawak, Malaysia), Greater Sunda Islands (Fig. 9).

Figure 9.  

Geographical distribution of known records of Mesoschendyla javanica (Attems, 1907). Panel near top left corner showing enlarged overview of Gunung Mulu National Park, where all new specimens presented here have been collected. black star = type locality, black circle = location of Gunung Mulu National Park in northern Borneo, white circle = georeferenced location from which M. javanica has been sampled.

The majority of specimens in the present sample were obtained from 10 cm diameter soil cores at depth of 10–20 cm manually searched for arthropods (Collins 1980), with only one (NHMUK015991403) being hand collected.

Abundance of centipedes in the soil core samples examined by Collins (1980) did not show any clear trend across the altitudinal transect sampled, with the majority of specimens being found in altitudinal zones B (52), J (52), K (57) and L (41). However, as a percentage of total macrofauna sampled, centipedes were recorded as more dominant at the higher altitude zonation sites J (9%), K (11%) and L (28%), only comprising 1–4% at the remaining sites (Collins 1980). Most M. javanica specimens (53%) have been collected from soil cores of mixed dipterocarp forest sites at altitudes below 500 m. Specimens with clear altitude zonation site data revealed that of the total number of centipedes sampled at each site (Collins 1980), M. javanica specimens accounted for 1.9% at site B (130 m), 34.4% at site D (500 m), 3.1% at site F (1130 m), 7.1% at site G (1310 m), 2.7% at site H (1650 m), 4.6% at site I (1860 m), 13.5% at site J (1930 m), 8.7% at site K (2070 m) and 2.4% at site L (2376 m).

The species diagnosis above identifies characters shared by the Java and Sarawak material that are consistent with their conspecificity. These include body size, an overlapping number of leg-bearing segments (overwhelmingly 31), restriction of pore fields to sternites 2–11 or 12 and the shape of the pore fields, lack of lappets on the first maxilla and clavate antennae.

The syntype male preserving the ultimate legs shows them to have a slightly shorter metatarsus than most Borneo specimens (Fig. 1J), but proportions of the tarsus change markedly through ontogeny and some large specimens from Borneo (Fig. 7B) match the syntype with respect to proportions of the podomeres.

Mesoschendyla javanica exhibits a relatively large degree of sexual dimorphism for Schendylidae. Other genera with the ultimate leg pair of males likewise swollen include Escaryus Cook and Collins, 1890 (Cook and Collins 1890), Plesioschendyla Ribaut, 1923 (Ribaut 1923), Marsikomerus Attems, 1938 (Attems 1938) and Gosendyla Chamberlin, 1960 (Chamberlin 1960). Presence or absence of a pretarsal claw on the ultimate leg is usually fixed in schendylid genera and the sexual dimorphism of this trait within a species (present in females, absent in males of M. javanica) is exceptional. Remarkably, all juvenile specimens in the present sample appear to be male according to the morphology of the ultimate leg telopodite (Fig. 8A). As only seven of 49 examined specimens are female, it is possible that females in earlier developmental stages are absent from the present samples.