Amphicnemis remiger Laidlaw, 1912

Dow, Rory A., 2019, Amphicnemis rigiketit sp. nov. from Sarawak, with notes on Amphicnemis remiger Laidlaw, 1912 (Odonata: Zygoptera: Coenagrionidae), Zootaxa 4701 (4), pp. 371-382 : 376-381

Amphicnemis remiger Laidlaw, 1912

Figs (2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 31)

Material examined. Holotype. ♂, Kuala Madalam , Limbang Division, Sarawak, Malaysia, 11 v 1911, leg. J.C. Moulton, in the Natural History Museum, London . Other material. All in authors collection. Brunei: 1 ♂, peat swamp forest, Kuala Belai Road , Belait District, 2 iii 2013, leg. RAD ; 4 ♂♂, same location, 4 iii 2013, leg. RAD ; 1 ♀, low pH swamp forest accessed from Lumut Pipeline Road East , Belait District, 8 iii 2013, leg. RAD ; 1 ♂, 1 ♀ (BRU13_COE103, in tandem with the male), same location, 13 iii 2013, leg. RAD ; 9 ♂♂, peat swamp for- est on Labi Road , Belait District, 11 iii 2013, leg. RAD ; 3 ♂♂, 1 ♀, remnant peat swamp forest near Seria , Belait District, 22 v 2013, leg. RAD ; 3 ♂♂, peat swamp forest near highway, Rassau area , Belait District, 31 v 2013, leg. RAD. Malaysia, Sabah : 1 ♀, Klias Forest reserve , 26 v 2014, leg. unknown ; 1 ♂, 1 ♀, Klias Forest Reserve , 31 v 2014, leg. unknown ; 1 ♂, Kampung Hiridian Forest Reserve , 28 v 2018, leg. unknown. Malaysia: Sarawak : 1 ♂, 2 ♀♀, Headhunters Trail, Gunung Mulu National Park, Limbang Division , 11 ii 2006, leg. J. Simun ; 2 ♂♂, Men- tawei Boundary Trail, Mentawei, Gunung Mulu National Park , Limbang Division , 13 ii 2006, leg. J. Simun ; 1 ♀ (SAR11_12_COE63), dry peat swamp forest near Sungai Dabai, Marudi, Miri Division , 5 ix 2011, leg. RAD ; 1 ♂ (SAR11_12_COE332), peat swamp forest on Brunei Trail , Marudi area, 6 ix 2018, leg. RAD ; 1 ♂, old rubber on peat, near Marudi, Miri Division , 8 ix 2011, leg. RAD .

Descriptive notes on male (based on SAR11_12_COE332).

Head ( Figs 2, 4 ). Labium entirely pale. Labrum black, narrowly pale centrally at free margin. Mandible bases black with cream outline except adjacent to genae. Genae pale, this extended narrowly beside compound eye to beyond level of antennae bases. Horizontal surface of clypeus shining black, vertical surface pale with intrusions of black from above ( Fig. 2 ). Vertical face of frons shining black becoming dark metallic green above, but largely occupied by irregular, pale transverse stripe very narrowly divided centrally, just joined to pale colour on genae. Rest of frons, vertex, occiput and underside of head bronzy metallic green. Ocelli whitish. Antenna bases with broad pale stripe on anterior face, this just extending to base of scape, scape black, pale at top, base of pedicel pale, this extended on anterior and posterior faces as stripe running almost to top, remainder brown, flagella missing.

Thorax. Prothorax ( Figs 10, 12 ) with pronotum almost entirely dark metallic green apart from pair of small pale marks at rear anterior pronotal lobe, propleuron mostly cream. Posterior pronotal lobe short, collar-like centrally but with rear lateral extremities sharply angulated, directed more to rear than to sides ( Fig. 12 ). Synthorax ( Fig. 18 ): mesepisternum, mesepimeron, most of mesokatepisternum and metepisternum to top of spiracle, and extending to metepleural suture adjacent to antealar carina, metallic green, remainder of synthorax whitish except dark mark near antealar carina on metepimeron. Legs (right anterior leg absent below trochanter) cream with flexor surface femurs white, poorly defined, incomplete narrow dark stripes on extensor surface femurs, dark brown to black spines, small dark mark lowest part femur and immediately adjacent part flexor surface tibia, black rings between tarsal segments, tips of pale brown claws black. Wings: 12 Px in Fw, 10 (left) or 11 (right) in Hw. Arculus slightly distal to Ax2. R 4 arising just distal to subnodus in all wings, IR 3 joined to it by a short stalk. Pterostigma almost trapezoidal with costal side shorter than anal side, dark brownish grey with whitish border (poorly defined on proximal side), covering ca one underlying cell.

Abdomen. S1 cream with apical transverse dark mark extended laterally apically. S2 metallic green above, cream below. S3–6 largely very dark brown above, cream lower laterally, this becoming darker on successive segments. S7 similar but almost entirely dark brown laterally in apical ca one-third. S8 bronzy black above, dark brown below. S9 entirely bronzy black, S10 white except dorsally where mostly brown. Anal appendages ( Figs 24, 26, 28 ) white. Cerci in lateral view with upper branch narrow at base, directed gently upwards from base, then straight before expanding along lower margin after half-length so that apical part is rounded ventrally and at apex ( Fig. 24 ). Lower branch of cercus tapering from base before expanding slightly subapically where directed gently upwards to narrow but rounded tip, a small dorsal black subapical tooth just visible in this view ( Fig. 24 ). In dorsal view ( Fig. 26 ) upper branch with a small subbasal subtriangular tooth after which contracted along inner margin before expanding again just after half length, the inner margin with an excised appearance between the subbasal tooth and the subapical expansion.A strong ridge runs to the apex along the outer margin, giving the expanded part the appearance of a heel-like shelf below it. In ventral view lower branch of cercus tapering gently from base, turning gently inwards at ca two-thirds length, a small, poorly defined subapical tooth on inner margin after which running straight or slightly outwards to rounded but marrow tip ( Fig. 28 ). Paraprocts short, pale with short finger like projection directed to rear in dorsal part (lateral view).

Measurements (mm). Abdomen without anal appendages 34, cercus ca 1, Hw 20.

Description of female (based on BRU13_COE103).

As male except as noted.

Head ( Figs 6, 8 ). More extensive pale area on labrum, pale stripe vertical face of frons broadly divided.

Thorax. Prothorax ( Figs 14, 16 ) almost entirely blue, anterior carina of anterior pronotal lobe black. Posterior pronotal lobe collar-like centrally in dorsal view ( Fig. 14 ), laterally contracted before slightly folded upwards and then extended downwards to rear as a subtriangular projection, free margin running downwards back to base ( Fig. 16 ). Postepimeral strip expanded to rear just below posterior pronotal lobe (this indicated with a white line in Fig. 16 ). Synthorax ( Fig. 20 ) bluish with yellowish cast dorsally (not apparent in life). Legs as male but marking on extensor surface femurs better defined as narrow black line. Wings with 12 Px in Fw, 11 Px in Hw, white border of pterostigma well defined on all sides.

Abdomen ( Fig. 22 ). Dark marks on dorsum not metallic until apical part S7. S8 yellowish basally laterally, otherwise brown laterally, bronzy black dorsally. S9 brown laterally, bronzy black dorsally with irregular bluish white lateral apical mark. S10 and anal appendages almost entirely bluish white. Ovipositor largely cream, not quite reaching level of tips of cerci apart from styles, which are brown.

Measurements (mm). Abdomen without anal appendages or ovipositor 36, Hw 22.5.

Notes on variation. As in A. rigiketit the main variation in markings in both sexes is in those of the anterior part of the head. R 4 occasionally arises at, rather than distal to, the subnodus in one or more wings. A very few males have the central part of the posterior pronotal lobe produced into a very short horn-like structure. Two males (not among those mentioned in the previous sentence) have the rear lateral extremities of the posterior pronotal lobe only slightly angulated. The subbasal spine on the upper branch of the male cercus is sometimes just visible in a typical lateral view, rarely is it clearly visible in such a view.

Measurements (mm). Males: 11–14 Px in Fw, 10–12 in Hw, abdomen without anal appendages 30–35, Hw 18–21. Females: 11–14 Px in Fw, 10–12 in Hw, abdomen without anal appendages or ovipositor 33–35.5, Hw 21–21.5.

Remarks. The holotype of A. remiger is from somewhere in the vicinity of the mouth of the Madalam River (Kuala Madalam), a tributary of the Limbang River, in Sarawak’s Limbang Division ( Laidlaw 1912), collected on the Sarawak Museum’s 1911 expedition to Mount Batu Lawi ( Moulton 1912). Later Laidlaw (1913: 72) mistakenly gave the type locality as Batu Lawi, possibly believing that Kuala Madalam is actually in the vicinity of the mountain (actually it is more than 70 km distant from it). I have compared recently collected specimens of A. remiger directly against the holotype (in the Natural History Museum, London) to confirm their identity. The holotype is a slightly immature individual, so a fresh mature male specimen was used for the description above.

The type locality is at low altitude and it is likely that the holotype was collected in swamp forest of some type. Most subsequent records, where the habitat is recorded, are also from swamp forest, often peat swamp forest, or streams in swamp or alluvial forest; my own specimens are from such habitats. Orr (2001: 183) states “common in swampy areas” for Brunei.

There is a rather puzzling record of this species in Laidlaw (1920: 336) where as well as again incorrectly giving the type locality as Batu Lawi, he lists two males, stated to be “imperfect”, from “Murud”, collected on the 20 th of December 1914. Murud presumably refers to Gunung Murud, the highest mountain in Sarawak. Collectors from the Sarawak Museum went to Gunung Murud, in late 1914 ( Moulton 1915), but it is not clear if they were still there in December and these specimens may have been collected somewhere on their route back. If these specimens were actually collected in the highlands it seems doubtful that they were actually A. remiger and might actually be the unnamed Amphicnemis species recorded in Dow et al. (2015) from Usun Apau and the Tama Abu Range (the range to which Gunung Murud belongs).

Laidlaw’s description of the male anal appendages of A. remiger is somewhat misleading. He states, referring to the upper branch of the cercus as the upper pair of anal appendages, “The shaft a little bowed with a small tooth at its middle” ( Laidlaw 1912: 96). However, the illustration of the anal appendages of the holotype ( Laidlaw 1912: Fig. 4 ) correctly shows the tooth in a subbasal position, as in all specimens that I have examined (including that illustrated here), although the tooth is only rarely visible in lateral view.

Amphicnemis remiger appears to have a rather restricted distribution in Brunei, immediately adjacent parts of Sarawak and extending to the south-west of Sabah ( Fig. 31 ). In Sarawak it has not been found west of the Baram River.

Figures

FIGURE 31. Distributions of Amphicnemis rigiketit sp. nov. (red circle) and Amphicnemis remiger (yellow square). Note that the problematic record of A. remiger from “Murud” (see the Remarks under A. remiger) is excluded from the distribution of that species.

FIGURES 1–4. Amphicnemis rigiketit sp. nov., head of holotype male: (1), dorsal-frontal view; (3) dorsal view. Head of male Amphicnemis remiger (SAR11_12_COE332); (2) dorsal-frontal view; (4) dorsal view.

FIGURES 9–12. Amphicnemis rigiketit sp. nov., prothorax of holotype male: (9), dorsal view; (11) lateral view. Prothorax of male Amphicnemis remiger (SAR11_12_COE332); (10) dorsal view; (12) lateral view.

FIGURES 17–20. Lateral view of synthorax of Amphicnemis spp. (17) Amphicnemis rigiketit sp. holotype male: (19) Amphicnemis rigiketit sp. nov., female described; (18) male Amphicnemis remiger (SAR11_12_COE332); (20) female Amphicnemis remiger (BRU13_COE103).

FIGURES 23–28. Amphicnemis rigiketit sp. nov., anal appendages of of holotype male: (23), dorsal view; (25) lateral view; (27) ventral view. Anal appendages of male Amphicnemis remiger (SAR11_12_COE332); (24) dorsal view; (26) lateral view; (28) ventral view. All scale bars 5mm.

FIGURES 5–8. Amphicnemis rigiketit sp. nov., head of female described: (5), dorsal-frontal view; (7) dorsal view. Head of female Amphicnemis remiger (BRU13_COE103); (6) dorsal-frontal view; (8) dorsal view.

FIGURES 13–16. Amphicnemis rigiketit sp. nov., prothorax of female described: (13), dorsal view; (15) lateral view. Prothorax of female Amphicnemis remiger (BRU13_COE103); (14) dorsal view; (16) lateral view. The expanded part of the postepimeral strip is indicated with a white line in Figs 15 and 16.

FIGURES 21–22. Lateral view of pattern of terminal abdominal segments of female Amphicnemis spp.: (21), Amphicnemis rigiketit sp. nov., female described; (22) Amphicnemis remiger (BRU13_COE103).