Leptogomphus pendleburyi Laidlaw, 1934

(Figs 1, 2, 3, 5, 13, 24, 32, 42, 47, 55, 67, 74, 84, 90, 96, 102, 108, 114, 122, 128, 135, 136)

Leptogomphus pendleburyi Laidlaw 1934: 555 –556, Fig. 1 (original description male, Kiau, Sabah);— Lieftinck 1954: 82;— Kimmins 1969: 297 (note on type);—van Tol 1990: 99, 101, 104, Figs 7, 9, 15, 28, 29, Table 1, 2 (key);—van Tol 1992: 177;— Hämäläinen 1994: 81;— Kalkman 2005: 14 (Kuala Belalong Field Studies Centre, Brunei);— Orr 2003: 40, 96; — Dow & Reels 2009: 14;— Dow & Ngiam 2014: 34 -35, Fig. 27 (both sexes, Ulu Balui, Sarawak).

Leptogomphus ? pendleburyi Dow et al. 2013a: 11, 14 (Mount Dulit).

Leptogomphus cf pendleburyi Steinhoff 2015: 8 (teneral female, GMNP).

Material studied. Type material. Holotype 1 ♂ (NHMUK 010595925), Kiau, Mount Kinabalu, Sabah, 6.034N, 116.517E (Kiau), ca 900m, 5 iv 1929, leg. H.M. Pendlebury, in BMNH.

Other material. Sarawak, Malaysia: 1 ♂ (SAR 13_14_GOM13, used for description and illustrations below), small steep stream near Sekawie Trail, Nanga Bloh Field Station, LEWS, Kapit Division, 1.65584N, 112.24797E, 26 viii 2013, leg. R.A. Dow, in collection Dow; 1 ♂ (teneral), tributary to Sungai Nyungan, same area, 1.65723N, 112.2432E, 14 iii 2016, leg. R.A. Dow, in collection Dow; 1 ♀ (SAR 16_GOM8), streams at Bukit Tanggan, ulu Mujok, LEWS, Sarikei Division, 1.6817N, 112.1519E (Sungai Sengkadan on way to Bukit Tanggan), 19 viii 2016, leg. R.W.J. Ngiam, in ZRC; 1 ♂, on old logging road, 800–900m, Sungai Kahei area, Ulu Balui, Kapit Division, 2.01295N, 114.67363E, 16 vi 2013, leg. R.A. Dow, in collection Dow; 1 ♀ (RMNH.INS.509949, semi-teneral), beside new logging road through virgin forest, same area, 2.05403N, 114.56557E, 8 ix 2013, leg. R.A. Dow, in RMNH; 1 ♂ (semi-teneral), stream on lower slopes Bukit Kana, Tatau district, Bintulu Division, 2.68208N, 112.90102E, 27 iii 2012, leg. B. Giman, in collection Dow; 1 ♂ (teneral), forest stream, foot of Gunung Kalulong, Upper Baram, Miri Division, 3.24821N, 114.68122E (Gunung Kalulong), 21 vii 2010, leg. R.A. Dow, in collection Dow; 1 ♀ (teneral, found sitting on exuvia), Deer Cave Stream upstream of waterfall, outside Garden of Eden, GMNP, Miri Division, 4.02785N, 114.83978E, 8 v 2014, leg. P.O.M. Steinhoff, in collection Steinhoff; 1 ♀ same location, 9 v 2104, leg. P.O.M. Steinhoff, in collection Steinhoff; 1 ♂, 1 ♀ (teneral) camp 2 stream systems, Gunung Mulu, same NP, Miri Division, 4.04752N, 114.86622E, 19 vi 2014, leg. P.O.M. Steinhoff, in collection Steinhoff.

Sabah, Malaysia: 1 ♂ (SAB 12_GOM3, RMNH.INS.507750, used for Fig. 96), Kimamabang waterfall stream, Inobong, Crocker Range NP, 5.9N, 116.117E, Inobong, 18 ix 2012, leg. R.A. Dow, in RMNH.

Brunei: 1 ♀, Kuala Belalong Field Studies Centre, Temburong district, 4.533N, 115.15E (Kuala Belalong Field Studies Centre), 20 xi 2004, leg. V.J. Kalkman et al., in RMNH.

Description of male (based on SAR13_14_GOM13). Head (Figs 5, 13). Median lobe labium dark brown, lateral lobes mostly pale but black at apices, hooks black. Labrum black with pale transverse basal mark, narrowly divided centrally and broken laterally (Fig. 13). Mandible bases mostly pale, genae mostly black. Clypeus black. Antefrons black, postfrons with pale transverse stripe (Fig. 13). Vertex and occiput black. Pair of transverse (somewhat diagonally orientated) tubercles behind lateral ocelli, rest of vertex smooth; ocelli dull orange. Occipital plate with low ridge to rear and central part raised to level of ridge, ridge with pair of widely spaced, very small horns.

Thorax. Prothorax mostly black and dark brown, anterior pronotal lobe with anterior carina pale except at lateral extremities, middle pronotal lobe with two large lateral marks and small posterior dorsal mark narrowly divided centrally. Pair of small mounds dorsally on middle pronotal lobe, bearing tiny tubercles. Synthorax black and dark brown with pale yellow-green markings as follows (Figs 55, 67): short mesothoracic collar, broadly divided at middorsal carina, joined to narrow dorsal thoracic stripes that taper toward wing bases, extending beyond level of apex of antealar crest, terminating just short of antealar carina. Small spot below dorsal thoracic stripe on mesepisternum, near antealar carina. Stripe running most of length of mesepimeron. Metepisternum with irregular stripe running from metakatepisternum, below spiracle, just separated from largely pale metakatepisternum and broadly separated from large spot at antealar carina (Fig. 67). A broad stripe centrally on metepimeron. Mesokatepisternum pale near leg. Venter pale with brown central area near abdomen. Legs robust and relatively short. Coxae pale and dark brown, remainder mostly black and very dark brown trochanters brown and black, interior surface of anterior femora with indistinct paler area. Wings: sectors of arculus separated at origin with 5 cross veins before first bifurcation of superior sector in Fw, 3 in Hw. Discoidal field with 2 rows of cells from origin, transitioning to 3 just before nodus in right wings, approximately at nodus in left. 12 (left) or 14 (right) Ax in Fw, 9 (left) or 10 (right) in Hw, 9 Px in all wings. Pt dark brown, covering ca 4 underlying cells.

Abdomen. Slender after base of S3, expanding moderately from base of S7, maximum width and height reached apical part of S8, then almost constant. Dorsum of S10 with pair of prominent ca conical protuberances basally (Fig. 108), bearing many small tubercles on posterior faces. Dark brown to black with pale markings as follows: S1 with lateral mark and dorsal mark. S2 pale lateral stripe running from base below and including most of auricle, except free margin of auricle, another pale lateral mark placed posteriorly, narrow yellowish middorsal stripe in apical ca two thirds. S3 with small basal lateral pale marking. S3–7 with very narrow middorsal line. S8– 10 entirely black. Cerci (Figs 102, 108) black, broad at base in lateral view (Fig. 108), tapering to sharp tip, along upper margin sloping down from base to ca two-thirds length, then up-turned to apex, along lower margin sloping down from base to ca mid length, where first gently, then more sharply, turned up to apex. In dorsal view (Fig. 102) relatively slender, outer margins running ca parallel from base, then turned in after midpoint, apex very slightly hooked out; inner margins curved in gently from base until near apices, where running parallel to one-another. There is a subapical ventrally directed spur on the cerci, barely or not visible in normal lateral or dorsal views; this is evident in ventral view but may be best seen in an oblique dorsal lateral view. Epiproct (Figs 102, 114) black, just shorter than cerci in lateral view (Fig. 108), deeply divided, margin between branches slightly concave, branches divergent (Fig. 114), tapering gently towards apices, which appear rounded in ventral view, apices outside those of cerci. In lateral view (Fig. 108) basal part of upper margin hidden by cercus, curved up to sharp point at apex, lower margin curved gently down then up to apex. Accessory genitalia as shown in Figures 90, 96, with anterior hamule moderate sized, directed postero-ventrally, irregularly tapering to rounded apex, ca three quarters height of posterior hamule. Posterior hamule broad, gradually tapering for much of length, hooked sharply forwards at apex. Vesicle subtriangular in lateral view.

Measurements (mm). Hw 23, abdomen excluding anal appendages 29.5, cerci ca 1.4.

Penis. The penis of a different specimen is shown (SAB12_GOM3) in Figure 95. Penultimate segment extended to rear of join with terminal segment, bifurcated in this part, apices turned ventrally. Terminal segment extended beyond penultimate segment, dorsal margin almost straight in lateral view in basal ca three-quarters, then shallow contracted before strongly expanding dorsally, apically with short cornua situated ventrally; a short ventrally directed flap placed just before the cornua.

Description of female (based on SAR16_GOM8, LEWS). As male except as noted. Head (Figs 24, 32, 42). Pale transverse basal mark on labrum only divided centrally (Fig. 47). Transverse tubercles behind lateral ocelli raised into short horns at their outer ends. Occipital plate with pair of long, slender occipital horns placed centrally, tips broken off on both. Pair of short, widely separated occipital spurs present.

Thorax. Narrow, faint antehumeral stripe running from the pale spot on the mesepisternum almost to mesokatepisternum, broadly interrupted centrally (Figs 74, 84). Legs (right anterior leg detached below coxa, left anterior with lower part tibia and tarsus broken off, trapped in mouthparts) with larger pale patch anterior femurs. Wings: sectors of arculus separated at origin with 5 (right) or 6 (left) cross veins before first bifurcation of superior sector in Fw, 3 (right) or 4 (left) in Hw. Discoidal field transitioning to 3 cell rows very slightly before nodus in both wings. 15 Ax in Fw, 10 Hw, 10 Px in all wings. Pt dark brown, covering ca 3.5 to 4 underlying cells.

Abdomen. Only very slightly expanded from base S7, lacking tubercles on S10. S2 with continuous lateral stripe over entire length, dorsal stripe also occupying whole length. Lateral mark base of S3 ca one third segment length, small basal lateral marks on S4–5. Middorsal line on S3-S7 less narrow, irregular. Cerci conical with sharp point, a little longer than S10. Vulvar scale (Fig. 122) shorter than S9, divided at ca half length, arms divergent, forming a “v” shape with a squared tip interiorly, outer edge almost straight to apex, inner edges straight until near apex, then curved out to apex.

Measurements (mm). Hw 26, abdomen excluding anal appendages 30.5.

Variation. Males. The basal part of the labium is sometimes paler than in the male described. The transverse mark on the labrum is not always divided centrally or broken laterally, this is the case in the holotype. The small horns on the occipital plate are only otherwise present on the teneral male from Sungai Nyungan and, on one side only, the teneral male from Gunung Kalulong; they are absent in the holotype. The male from Inobong has a partial, thin antehumeral marking in the anterior part of the mesepisternum. The male from Sungai Nyungan has a partial middorsal line on S8. The tip of the left cercus is broken off in the holotype, and the branches of the epiproct are more broadly divided at base, forming an open “u” shape rather than a “v”. The ventral subapical spur on the cercus is always present but varies somewhat in shape and size. There is considerable variation in size, the holotype is the largest specimen available, with an abdomen length (excluding anal appendages) of ca 37mm; both hindwings are broken so they cannot be measured. The male used for description here is the smallest available specimen.

Measurements (mm). Hw 25.5–27.5, abdomen excluding anal appendages 33–37, 12–18 Ax in Fw, 9–13 in Hw, 8–14 Px in Fw, 9–13 Px in Hw.

Females. There is similar variation in the markings of the head and thorax to that in the male; the incomplete faint antehumeral stripe is only present in two of the other females examined. The stripe on the metepisternum is almost complete on the female from Kuala Belalong. The outer ends of the tubercles behind the lateral ocelli are not raised into short horns on any other specimen available. One or both of the occipital horns is broken in all specimens except that from Kuala Belalong, in one specimen the left horn is broken at base but there are two, crowded close together, on the right.

Measurements (mm). Hw 26–28, abdomen excluding anal appendages 30–32, 15–20 Ax in Fw, 9–12 in Hw, 10–14 Px in Fw, 9–12 Px in Hw.

Remarks. The female of L. pendleburyi had not been described until now. It is associated with the male here by similarity of markings and in the ITS marker; COI was not successfully extracted from the female specimen sampled for DNA.

Leptogomphus pendleburyi is known from streams in mixed dipterocarp forest in Brunei, Sabah and Sarawak (Fig. 128); its occurrence in Kalimantan is likely.