Leptogomphus williamsoni Laidlaw 1912
Creators: name: Dow, Rory A.
name: Stokvis, Frank
name: Ngiam, Robin W. J.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Gomphidae
Leptogomphus
Leptogomphus williamsoni

description: Leptogomphus williamsoni Laidlaw, 1912
(Figs 1, 2, 3, 9, 17, 26, 34, 44, 50, 59, 63, 76, 86, 93, 99, 105, 111, 117, 125, 129, 132, 137)
Leptogomphus williamsoni Laidlaw 1912: 94 –95, Figs 1, 2 (original description male, Madihit, Sarawak);— Lieftinck 1948: 247 –249, Plate 8, Fig. 10 (description of ♀, Kutai);— Lieftinck 1954: 83;— Kimmins 1969: 299 (note on type);— Tsuda & Kitagawa 1989: 38 (♂, Poring);—van Tol 1990: 98, 99, 101, 102, Figs 17, 26, 27, Table 1, 2 (key);—van Tol 1992: 236;— Orr 2003: 40;— Dow & Ngiam 2012: 14 (both sexes, Hose Mountains, Sarawak);— Ngiam & Dow 2013: 307, 309–311, Figs 1b, 3b, 4 (♀, larva, Hose Mountains, Sarawak);— Dow & Ngiam 2014: 35, Fig. 28 (both sexes, Ulu Baleh and Ulu Balui, Sarawak);— Dow et al. 2015a: 27 (locations in Kapit Division, Sarawak).
Material studied. Type material. Holotype 1 ♂ (NHMUK 010595516), Madihit, Sarawak, Borneo, 3.8707N, 115.3866E (Batu Lawi, Madihit on route taken by Moulton to Batu Lawi), ca 600m, 4 vi 1911, leg. J.C. Moulton, in BMNH.
Other Material. Sarawak, Malaysia: 1 ♀, small tributary to Sungai Engkari, Nanga Segerak, LEWS, ulu Engkari, Sri Aman Division, 1.41376N, 112.00449E (Ulu Engkari), 15 vii 2016, leg. G.T. Reels, in collection Dow; 1 ♀ (teneral), tributary to Sungai Segerak, same area, 1.41186N, 112.00518E, 17 vii 2016, leg. G.T. Reels, in collection Dow; 1 ♂ (SAR 16_GOM1, used in Fig. 99), seepage by small stream next to field station, Nanga Bloh, ulu Katibas, LEWS, Kapit Division, 1.64617N, 112.27592E, 12 iii 2016, leg. R.A. Dow, in collection Dow; 1 ♂ (teneral), Sungai Nyungan, same area, 1.65723N, 112.2432E, 14 iii 2016, leg. E. Jangoh, in collection Dow; 1 ♂ (teneral), Sungai Menyarin, same area, 1.65518N, 112.21832E, 15 iii 2016, leg. R.A. Dow, in collection Dow; 1 ♂ (RMNH.INS.501379), tributary to Sungai Ulu Yong, Kapit town area, Kapit Division, 1.94N, 112.828E (Sungai Ulu Yong), 21 x 2009, leg. R.A. Dow, in RMNH; 1 ♀, small stream in disturbed forest, Nanga Gaat area, Kapit Division, 1.74723N, 113.3487E (Nanga Gaat area), 5 ix 2015, leg. M. Budi, in collection Dow; 1 ♀ (teneral), stream in virgin forest, Sungai Kahei area, Ulu Balui, 2.046N, 114.572E, 15 vi 2013, leg. M. Budi, in collection Dow; 1 ♀ (teneral), same area, 2.038N, 114.602E, 10 ix 2013, leg. L. Southwell, in collection Dow; 1 ♂ (semiteneral), stream 800-900m in disturbed forest, same area, 2.012N, 114.672E, 16 vi 2013, leg. L. Southwell; 1 ♂ (teneral), streams 660-840m, Gunung Kajang area, Hose Mountains, Kapit Division, 2.29768N, 113.69733E (Gunung Kajang area), 9 iv 2011, leg. R.A. Dow; 1 ♀ (RMNH.INS.503842), stream at ca 740m, same area, 2.29768N, 113.69733E (Gunung Kajang area), 13 iv 2011, leg. M. Kibi, in RMNH; 1 ♂ (teneral), Sungai Sagan Besai, foot of Hose mountains, Kapit Division, 2.06478N, 113.67565E (general coordinates for area), 25 ix 2011, leg. M. Budi, in collection Dow; 1 ♂ (RMNH.INS.504046; teneral), streams ca 860-940m, Stone Park, Batu Laga Plateau, 2.38279N, 114.06441E (Stone Park area), 29 ix 2011, leg. L. Southwell, in RMNH; 1 ♂ (SAR 11_12_GOM56, used for description and illustrations), Bukit Naong, Tatau district, Bintulu Division, 2.68512N, 112.86433E, 22 iii 2012, leg. N. Megom, in collection Dow; 1 ♂ (RMNH.INS.506248; teneral), stream in block A1M, Tatau district, Sarawak Planted Forest Project, Bintulu Division, 2.6959N, 112.88629E, 24 iii 2012, leg. R.A. Dow, in RMNH; 2 ♂♂ (one teneral), same location, 25 iii 2012, leg. R.A. Dow, in collection Dow; 1 ♂ (RMNH.INS.506250, teneral), same data, in RMNH; 1 ♀, small high gradient stream, Tubau, Sarawak Planted Forest Project, Bintulu Division, 3.14335N, 113.65E (Tubau area), 17 viii 2009, leg. R.A. Dow, in collection Dow; 1 ♂, small stream, same area, 3.14335N, 113.65E (Tubau area), 31 viii 2009, leg. R.A. Dow, in collection Dow; 1 ♀, stream in Lio Mato water catchment area, Lio Mato, Upper Baram, Miri Division, 3.16N, 115.234E, 13 x 2009, leg. R.A. Dow, in collection Dow; 1 ♂ (semi-teneral), by logging road from Sungai Sii to Sungai Alah, Sungai Sii, upper Baram, Miri Division, 3.0151N, 114.9097E (Sungai Alah), 17 vii 2014, leg. R.A. Dow, in collection Dow; 1 ♀ (SAR 13_14_GOM51; used in illustrations), tributary to Sungai Sii downstream from camp, same area, 2.99147N, 114.90256E (Sungai Sii), 17 vii 2014, leg. R.W.J. Ngiam, to be deposited in ZRC; 1 ♀, stream on Gunung Kalulong, Upper Baram, Miri Division, 3.19038N, 114.6968E, 700-800m, 17 vii 2010, leg. R.A. Dow, in collection Dow; 1 ♂ (semi-teneral), 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 coll. Steinhoff; 1 ♀ (teneral) same location, 9 v 2014, leg. P.O.M. Steinhoff, in coll. Steinhoff; 1 ♀, parallel tributary of Deer Cave Stream, upstream of Garden of Eden Waterfall, same NP, 4.02656N, 114.84297E, 8 v 2014, leg. P.O.M. Steinhoff, in coll. Steinhoff; 1 ♀, same location, 22 v 2014, leg. P.O.M. Steinhoff, in coll. Steinhoff; 1 ♀, stream systems at “camp 2”, lower slopes Gunung Mulu, same NP, 4.04752N, 114.86622E, 31 v 2014, leg. P.O.M. Steinhoff, in coll. Steinhoff; 1 ♂, same location, 19 vi 2014, leg. P.O.M. Steinhoff, in coll. Steinhoff; 1 ♀, second order tributary to Sungai Lansat, same NP, 4.006N, 114.82E (Long (mouth of) Lansat), 23 vii 2014, leg. P.O.M. Steinhoff, in coll. Steinhoff.
Kalimantan Timur, Indonesia: 1 ♀, Dagaunan, Sangkulirang, 0.977N, 117.9803E (Sangkulirang), vi 1937, leg. M.E. Walsh, in RMNH; 1 ♀ (semi-teneral), Tabang, Bengen River, East Kalimantan, 0.5667N, 116.0333E (approximate coordinates for Tabang), 125m, 30 ix 1956, leg. A.M.R. Wegner, in RMNH.
Kalimantan Selatan, Indonesia: 1 ♀, Sungai Kuinam, Gunung Pisang primary forest, 5 km SSE of Belangian village, Aranio District, Banjarbaru, - 3.5059N, 115.0923E, 250m, 11 xi 1996, leg. M. Bedjanič, in collection Dow.
Description of male (based on SAR11_12_GOM56). Head (Figs 9, 17). Median lobe labium dark brown, pale basally except laterally; lateral lobes pale, hooks dark brown and black. Labrum black with pale transverse basal mark. Mandible bases pale, genae pale adjacent to mandible bases, otherwise black. Clypeus mostly black with rather indistinct brown markings at anterior corners of postclypeus, very faint mark centre anteclypeus. Ante- and postfrons not very sharply divided, postfrons almost entirely pale bluish (Fig. 17). Pair of prominent ca transverse tubercles behind lateral ocelli; ocelli orange. Vertex and occiput black with large pale mark on vertex behind and extending onto rear parts tubercles.
Thorax. Prothorax mostly dark brown, pale transverse stripe anteriorly on anterior pronotal lobe. Pair of lateral posterior pale marks, central posterior mark (divided centrally), pair small pale marks, widely separated dorsalanteriorly on middle pronotal lobe. Propleuron mottled dark brown and pale. Tiny central pale mark on posterior pronotal lobe. Synthorax dark brown with pale yellow-green markings as follows (Figs 59, 63): broad mesothoracic collar, just divided at middorsal carina, separated from short narrow dorsal thoracic stripes that extend just past apex of antealar crest. Broad antehumeral stripes. Most of rest of synthorax laterally pale, except a broad brown stripe around mesopleural suture, small brown area on metepisternum above spiracle, ca diagonal brown mark centrally on metepisternum and another brown mark adjacent to antealar carina, Metepimeron brown below metakatepisternum, this extended along lower margin to antealar carina. Mesokatepisternum dark brown above, pale below contiguous with antehumeral stripes, metakatepisternum mostly pale. Metapoststernum pale with brown lateral marks in anterior ca two-thirds. Legs robust and relatively short. Coxae mottled pale, grey and brown, trochanters black and pale. Rest of legs black except inner surface of anterior femora with pale stripe.
Wings: sectors of arculus separated at origin with 6 (right) or 5 (left) cross veins up to and at first bifurcation of superior sector in Fw, 4 (right) or 3 (left) in Hw. Discoidal field with 2 rows of cells from origin, transitioning to just three rows well before level of nodus in both wings. 14 Ax in Fw, 9 in Hw, 11 (left) or 12 (right) Px in Fw, 11 in Hw. Pt pale brown, covering ca 3-4 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. Very dark brown to black with pale markings as follows: S1 mostly pale laterally, obscure pale marks dorsally. S2 central lateral pale mark running from base, including auricle, narrowly divided from posterior yellow mark that extends anteriorly along lower margin tergite, narrow yellowish middorsal stripe not quite reaching apex of segment, wider apically. S3 with basal lateral pale marking, S4–7 with small lateral markings at base. S3–7 with narrow, irregular middorsal line, on S7 slight expanded apically. S8 pale brown behind posterior carina. S10 distinctive yellow-green subcircular mark centrally on dorsum. Cerci (Figs 105, 111) black and dark brown, broad at base in lateral view (Fig. 111), tapering to sharp upturned tip, small basal dorsal mound visible, upper margin sloping steeply down from this to after mid-length, then gently curved to apex, along lower margin sloping down from base to ca half length, then abruptly up and in to apex, very prominent corner at upturn, first half of upturned section of lower margin bearing small teeth. In dorsal view (Fig. 105) outer margin running straight from base or slightly outward, then inward to tips at ca half length; prominent corner on lower margin clearly visible. Black, brown at base laterally, this more extensive dorsally. Epiproct (Figs 105, 117) black and dark brown, pale central basal area ventrally, just shorter than cerci, deeply divided in an almost semicircular shape, outer margins gently divergent to near apices, apices rounded. In lateral view (Fig. 111) directed down from base then up before mid-length, apices just under tips of cerci, turned almost to rear; basal part of upper margin obscured by cerci. Accessory genitalia as shown in Figures 93, 99 (Fig. 99 shows a different specimen), with anterior hamule moderate sized, tapering toward sharp apex, slightly hooked to rear at apex. Posterior hamule large, ca twice length of anterior hamule, directed postero-ventrally, anterior margin converging on posterior margin for much of length, then whole curving gently forward so directed down, tapering to sharp tip, directed slightly outward. Penis vesicle prominent, ca half height of posterior hamule.
Measurements (mm). Hw 25.5, abdomen excluding anal appendages 29.5, cerci ca 1.5.
Penis. Examined in SAR16_GOM1 (Fig. 99), very similar to that of L. schieli. Penultimate segment extended to rear of join with terminal segment, bifurcated in this part, apices slender, curved down, shorter than in L. schieli. Terminal segment extended well beyond penultimate segment, approximately dumbbell shaped in lateral view, then shallowly contracted before strongly expanding dorsally, apically with short rearward directed, curled, cornua; short, rearward directed flap just below cornua.
Variation in examined males. There are frequently well-defined yellow markings on the clypeus, particularly in teneral and semi-teneral individuals; this is the case in the holotype where there are lower lateral marks and an upper central mark on the post clypeus. There is no yellow mark on the posterior pronotal lobe in any other individual, and the smaller, dorsal-anterior marks on the middle pronotal lobe are frequently absent, but sometimes joined to the larger lateral ones. The dorsal marking on the head is frequently smaller, and sometimes divided into two. The dorsal thoracic stripes are sometimes shorter than in Figure 59. There are frequently more extensive brown markings on the metepisternum. Most mature individuals have a dark central area on the metapoststernum near the abdomen. The coxae are entirely yellowish in the holotype. There are often pale stripes on the upper inner surface of the anterior femur, and less often pale marks in various positions on the middle and posterior femur in mature individuals; in teneral individuals the legs are extensively pale. In some mature individuals Pt is darker than in the male described. The yellow middorsal mark on S7 is often not at all expanded apically and in the holotype and one semi-teneral from GMNP there is a narrow yellow middorsal mark on S8 as well. Small, lateral apical markings are occasionally present, especially in teneral and semi-teneral individuals, on any of S7, S8 or S10 (and are presumably possible on S9). In the holotype there is a fairly large lateral marking on S8, approximately in the form of an elongate triangle based at the apex of the segment, but there is no basal mark on S7. The dorsal pale mark on S10 is sometimes smaller, in one individual it is divided and in the non-teneral male from Nanga Bloh it is completely absent. In the holotype the cerci and epiproct have substantial paler brown areas. The shape of the area between the arms of the epiproct varies from that in the male described here to a broad “v” shape (this is the condition seen in the holotype).
Measurements (mm). Hw 24–26, abdomen excluding anal appendages 29–31, 13–15 Ax in Fw, 9–11 in Hw, 10–13 Px in Fw, 8–11 Px in Hw.
Descriptive notes on the female. Lieftinck (1948) gave a detailed description of a female from eastern Kalimantan (the female from Dagaunan listed above), including illustrations of the dorsum of the head, the markings of the thorax and the vulvar scale. The other females that we have examined agree well with Lieftinck’s description in most respects; females from south-west Sarawak are discussed separately below. There is variation of course, with individuals differing in some details of markings (similar to the variation seen in males), wing venation and in measurements. There are two main areas of difference from the female described by Lieftinck: the markings of the abdomen and the structures on the occipital plate.
Lieftinck (1948: 249) described the markings of the abdomen of his female as follows: “Segm. 1 largely yellowish laterally, 2 without visible light side-markings (apparently discoloured); 3–7 each with a fairly large, oval, basal lateral yellow spot. 4 and 5 moreover with a longitudinal streak of the same colour placed on each side of segment a little distal to the middle, and 2–7 with a continuous middorsal line, widest on 2. Terminal segments black.” In all specimens examined by us, S1 is yellow dorsally as well as laterally, S2 has a lateral yellow stripe running the length of the segment and including the small, rounded auricle. S3 has a stripe running from base for most of the segment, narrowly divided before its midpoint. S4–7 have the basal lateral spot; the “longitudinal streak” is present on S4–6 and usually on S7, but diminishes in size on successive segments, so that it is typically a small spot on S6 and S7. The dorsal markings agree with Lieftinck’s description.
In the female described and illustrated in Lieftinck (1948), and that shown in Figures 26, 34, 44, 50 here, both occipital horns and occipital spurs are present. The occipital spurs are short, robust and widely separated; they are present in all females we have examined, although they show some variation in length. The occipital horns, long and sharp in those figured and in Lieftinck’s illustration, are entirely absent in five of the 17 females we have examined, and only present on one side in another four. Close examination gives no indication that the horns have been broken in these cases; they are evidently undeveloped. In other individuals one or both horns are clearly broken, but there is also some variation in length. In the female from Tubau the basal half of the horns is swollen and brown. Between the occipital horns there are a pair of gentle swellings on the occipital ridge, visible in Lieftinck’s (1948) illustration, but not mentioned in his description. These are typically present but variably developed, and most conspicuous in females that lack the horns. There is a shallow pit or depression outside of the tubercles behind the lateral ocelli.
In addition, there is some variation in the dorsal thoracic markings (Figs 76, 86), for instance in the semiteneral female from Tabang the dorsal thoracic stripes are almost completely joined to the mesothoracic collar.
Measurements (mm). Hw 25–28.5, abdomen excluding anal appendages 27–33, 13–17 Ax in Fw, 9–12 in Hw, 10–12 Px in Fw, 9–12 Px in Hw.
Remarks. The fact that either two, one or no occipital horns are present on the occipital plate of females demonstrates that in this species the occipital horns are variable and non-diagnostic. The occipital spurs, however, are always present.
Laidlaw (1912) states that the abdomen plus anal appendages of the holotype measure 34 mm, but the first author measured it as 31 mm excluding anal appendages.
Leptogomphus williamsoni exhibits considerable variation in its COI marker, with the five sequences available only agreeing in 90.6% of sites. With ITS, sequences from the same five specimens agree at 90.8% of sites, but this relatively low agreement is almost entirely due to the fact that most of the section of 28S included is excluded in one sample due to poor quality, and a smaller part of 16S in the same sample. When the comparison only includes the parts of 16S and 28S present in all sequences analysed, the sequences are identical at more than 99% of sites; this agreement is evident in Figure 2 where the sequences appear almost identical. Given the variation seen in COI in this species, we do not consider that the difference seen in this marker with L. sp. cf williamsoni (see below), for which no ITS sequence was obtained, to provide conclusive evidence that the two are separate species, although this is likely.
Leptogomphus williamsoni is known from Sarawak, Sabah and east and south-east Kalimantan (Fig. 129). It is likely to occur in parts of Brunei and to be more widely distributed in Kalimantan than we currently know. Records from Sarawak west of the Lupar River may belong to a separate species and are discussed as L. species sp. cf wiliamsoni below. This species occurs at streams in mixed dipterocarp forest in hilly and mountainous terrain.
description: Published as part of Dow, Rory A., Stokvis, Frank & Ngiam, Robin W. J., 2017, Revision of the Genus Leptogomphus Selys in Borneo, including gene trees and a two marker molecular phylogeny (Odonata: Anisoptera: Gomphidae), pp. 201-257 in Zootaxa 4358 (2) on pages 230-236, DOI: 10.11646/zootaxa.4358.2.1, http://zenodo.org/record/1067996