Amphicnemis reri, Dow & Gesriantuti & Lupiyaningdyah, 2025

Dow, Rory A., Gesriantuti, N. & Lupiyaningdyah, P., 2025, A new species of Amphicnemis Selys, 1863 from Sumatra, Indonesia and first records of two other species of Amphicnemis for the island (Odonata: Zygoptera: Coenagrionidae), Zootaxa 5659 (2), pp. 273-282 : 277-280

Amphicnemis reri sp. nov.

( Figs 2, 3 , 9 , 11 )

Holotype. 1 ♂ ( RER23_COE36 , MZB.Odon.31432 ), pools in PSF, Meranti Estate Block B Transect, Kampar Peninsula , Pelalawan, Riau, Sumatra, Indonesia, 0.3363N, 102.6440E, ca. 5–9 m a.s.l. 7 ii 2023, leg. R.A. Dow, deposited in BRIN.

Paratypes. All from Kampar Peninsula , Pelalawan, Riau, Sumatra, Indonesia, all sites in the range ca. 5–9 m a.s.l.: 2 ♂♂ ( RER23_COE37-38 ) , 1 ♀ ( RER23 _ COE39 ), pools in PSF, Meranti Estate Block B Transect , 0.3363N, 102.6440E, 7 ii 2023, leg. R.A. Dow ; 1 ♀ ( RER23 _ COE194 ), same location, 8 vi 2023, leg. R.A. Dow ; 1 ♂ ( RER20_COE68 ), PSF (flooded by Sungai Serkap ) behind fishermen’s huts downstream from ranger post, Sungai Serkap, 0.3613N, 102.7122E, 18 i 2020, leg. R.A. Dow ; 6 ♂♂ ( RER23 _ COE47-52 ), PSF (flooded) around Simpang Sianyir, tributary of Sungai Serkap , 0.5035N, 102.5773E, 16 ii 2023, leg. R.A. Dow ; 1 ♂ ( RER23 _ COE41 ) , 1 ♀ ( RER23 _ COE40 ), shorter trail in PSF from GHGFM tower, 0.4006N, 102.7584E, 8 ii 2023, leg. R.A. Dow ; 1 ♂ ( RER23 _ COE149 ), same location, 13 ii 2023, leg. R.A. Dow ; 1 ♀ ( RER23 _ COE195 ), same location, 13 vi 2023, leg. R.A. Dow ; 3 ♂♂ ( RER23_COE42-44 ), transect in PSF behind Sangar Pos (Sangar ranger post), Sungai Sangar, 0.3952N, 102.8421E, 9 ii 2023, leg. R.A. Dow .

Etymology. The species epithet, reri , is a noun in the genitive case, formed from the acronym of Restorasi Ekosistem Riau (RER), who manage the area in which the species was discovered.

Description of holotype. Head. Labium entirely pale. Labrum black, cream in lower ca. one quarter except at lateral extremes. Mandible base cream on right, on left with large central brownish mark. Genae cream, this extending beside compound eyes onto the underside of the head for a short distance and narrowly upwards towards the antennae bases. Horizontal surface of clypeus shining black, vertical surface black with small pale lateral marks and narrow central transverse stripe adjacent to labrum. Vertical face of frons shining black with complete, broad cream transverse stripe adjacent to clypeus. Rest of frons, vertex, occiput and underside of head very dark, metallic greenish black. Ocelli whitish. Antenna bases with broad yellowish stripe on anterior face, scape black, yellow at top, pedicel brown, dull yellow stripe running most of length of anterior and posterior faces, flagella brown.

Thorax. Prothorax mostly dark metallic greenish black, indistinct pale areas laterally on rear part of anterior pronotal lobe, lower parts of propleuron cream with boundary between two colours irregular. Posterior pronotal lobe ( Fig. 2 ) short, with rear lateral extremities produced as outward, downward and rearward directed, subtriangular projections, rounded at apices; centrally produced at rear into long horn, directed upwards and rearwards, this horn longer than the anterior and middle lobes of the pronotum combined, of almost even width after base. Synthorax: mesepisternum, most of mesepimeron, most of mesokatepisternum, small area of metepisternum adjacent to antealar carina (this continued slightly onto the metepimeron) and upper part of rest of metepisternum dark metallic green, remainder of synthorax cream. Legs (left anterior and middle legs absent below trochanter) cream except flexor surfaces of femur white, dark brown to black spines, small dark mark lowest part femur and immediately adjacent part of flexor surface of tibia, poorly defined dark rings between tarsal segments, tips of claws black; also narrow dark stripe on extensor surface of femur separated from trochanter, thin and faint at top, becoming broader and better defined lower down, continuing to joint with tibia. Remaining anterior tibia also with dark area on upper extensor surface. Metaposternum with clump of moderately long, fine setae conspicuous in lateral view. Wings: 12 (left) or 13 (right) Px in Fw, 11 in Hw. Arculus slightly distal to Ax2. R 4 arising distal to subnodus in all wings, IR 3 joined to it by a short stalk. Pt almost trapezoidal with costal side shorter than anal side, covering ca. one underlying cell (slightly less in right FW); dark brown with well-defined whitish border, this widest on costal side, narrowest and faintest on subcostal side.

Abdomen. S1 cream laterally, dark and slightly metallic above, this dark colour extending diagonally rearwards laterally; band of setae, slightly shorter on average than those on metaposternum, on tergite on either side of sternite. S2 metallic dark above, cream below and in narrow basal annulus interrupted dorsally, entirely dark behind posterior carina. S3–6 largely dark brown above, cream lower laterally (e.g. immediately above sternite), with pale basal annulus interrupted dorsally (becoming fainter on successive segments) and dark laterally apically. S7 similar but almost entirely brown laterally, basal annulus poorly defined. S8 dark bronzy brown above, paler lower laterally. Tergite of S9 almost entirely dark bronzy brown, sternite mostly pale, genital valves slightly pointed apically, apices just reaching apex of sternite. S10 pale laterally with most of dorsum brown.

Anal appendages ( Figs 9 , 11 ) whitish. Cerci in lateral view ( Fig. 9 ) with upper branch narrow at base, directed gently upwards along lower margin, narrowing slightly to ca. two-thirds length where abruptly expanded on lower margin and turned down, somewhat hatchet like, expanded apical part subrectangular, gently rounded at end with slight ventral notch. Lower branch tapering from base, directed gently and very slightly down, slightly expanding along upper margin at apex with black dorsal interior tooth just before apex. In dorsal view ( Fig. 11 is a sketch of this view) upper branch of cercus with well-defined, rearward and inward directed, sharply pointed interior projection before half-length, not visible in lateral view; expanded apical part appearing as broad rounded heal on inner margin, separated from a thumb-like apex by a broad notch. In ventral view lower branch tapering slightly from base, apex abrupt, almost square. Paraprocts short, pale with short, blunt projection directed to rear in dorsal part (lateral view).

Penile organ. Examined in detail in the holotype and paratype RER23_COE149, of typical form for members of the Amphicnemis wallacii Selys, 1863 -group ( Figs 4–5 show lateral views of the penile organ of two members of the wallacii -group from Borneo: A. annae Lieftinck, 1940 and A. wallacii respectively) with a broad terminal segment without lateral arms but with a robust central flagellum arising from the dorsal surface of the segment, directed back along the shaft, extending well beyond the rest of the terminal segment. The central flagellum is somewhat longer in A. reri and broad towards its apex, otherwise very similar to those shown in Figs 4–5 .

Measurements (mm). Abdomen with anal appendages ca. 36, cercus ca. 1, Hw 20.

Female (based on RER23_COE40; supposition). Overall similar to male except in its non-metallic colouration and as noted below. Head. Lower ca. one-third of labrum pale. Large dark patches on mandible bases. A pair of faint pale marks on occipital ridge behind lateral ocelli.

Thorax. Prothorax mostly dull bluish, anterior carina of anterior pronotal lobe black; posterior pronotal lobe ( Fig. 3 ) relatively shallow (not covering the mesostigmal area) with rear lateral extremities slightly broader than in male; horn directed straight up after base, shorter than in male, ca. as long as middle lobe of pronotum. Postepimeral strip slightly, smoothly expanded centrally to rear of propleuron. Synthorax bluish, dorsum with a strong yellow cast, however this is an artefact of preservation, in life a slight greenish cast. Remainder bluish, this extending onto parts of anterior and middle coxae, venter cream. Legs with upper part of dark stripe on extensor surface of femur broader and better defined than in holotype male. Wings with 12 Px in Fw, 11 (left) or 12 (right) Px in Hw. Pt greyish brown, pale border narrower than in male and as narrow and faint on basal side as well as on subcostal side.

Abdomen. S8 more extensively pale laterally. S9 blackish with poorly defined pale lateral mark in apical half. S10 mostly whitish, brown ventrally. Cerci whitish, little shorter than S10, an epiproct between them, just visible even in lateral view. Ovipositor largely pale, not extending further than tips of cerci except for brown and pale styles.

Measurements (mm). Abdomen with anal appendages and ovipositor 35.5, Hw 21.5.

Variation in paratypes.

Males. There is considerable variation in the extent and shape of dark colour on the mandible bases, more extensive pale colour on the labrum and vertical face of the clypeus than in the holotype in some individuals and the pale colour on the genae is frequently more obviously extended narrowly upwards beside the compound eyes. The lateral projections of the posterior pronotal lobe are narrower and more finger-like in some paratypes and the central horn is sometimes curved forward in its upper part so that the apex is directed almost vertically. The extent of dark colouration on the metepisternum is variable. The border of the Pt is fainter and narrower in some individuals, in others it is more well defined and of almost even width on all sides. In less mature individuals the pale colour on thorax, legs and abdomen is strongly yellow, and the Pt is paler.

Females. One female paratype is semi-immature with a reddish thorax and legs, also some reddish colour on abdominal S1 and S2 laterally. In general there is similar variation in the markings of the head to that seen in the male. The Pt has a broader pale margin than in the female described in two paratypes. The abdominal S9 pale mark in apical half varies in size from the female described, as does the dark area on S10 lower laterally.

Measurements (mm). Males: 11–13 Px in Fw, 10–13 (13 in one wing of one individual only, 11 or 12 most common) in Hw, abdomen with anal appendages 34–36.5, Hw 19–19.5. Females: 12–13 Px in Fw, 11 in Hw, abdomen with anal appendages and ovipositor 35–36.5, Hw 20–21.5.

Diagnosis. The male of A. reri is easily separated from all known species of Amphicnemis except A. annae , A. madelenae Laidlaw, 1913 , A. pandanicola Lieftinck, 1953 and A. triplex Dow, 2014 (all of which are known only from Borneo) by the long horn of the posterior pronotal lobe, clearly longer than the length of the dorsum of the middle pronotal lobe. Of the species with a very long posterior pronotal lobe horn in the male, A. madelenae and A. pandanicola belong to a different species-group and can easily be separated from A. reri by the completely yellow Hw pterostigma in these species (brown with whitish border in A. reri ). Amphicnemis triplex has very different anal appendages, in particular the triple lobed apex of the lower branch of the cercus clearly differentiates it from A. reri . Amphicnemis annae has the most similar anal appendages to A. reri but (compare Figs 8 and 10 with Figs 9 and 11 ) differs in the form of the upper branch of the cercus – that of A. annae seen laterally expands almost evenly to apex, not appearing at all hatchet like, and has a prominent inward and upward directed interior projection, clearly visible in lateral view, the interior projection on the cercus of A. reri is directed inward but not upward and is not visible in lateral view. The male of A. reri can easily be distinguished from those of all other Amphicnemis species known to occur in Sumatra (and Peninsular Malaysia) by the long posterior pronotal lobe horn ( Fig. 2 ) alone.

The (supposed) female of A. reri is similar to those of both A. gracilis and A. bebar but differs in details of the posterior pronotal lobe – shallower than that of A. bebar (even taking the variation in that species noted above) and the slightly downward directed and produced corners of the free margin, different from the corners of the free margin in A. gracilis . The reader should compare Fig. 3 here with Fig. 3 ( A. bebar ) and Fig. 5 ( A. gracilis ) in Dow et al. (2010). Separation of female Amphicnemis is generally difficult and we doubt that any combination of characters completely and clearly separates the female of A. reri from that of all other species within the A. wallacii -group.

Remarks. Although none were taken in tandem, the female is associated with the male by reasonable supposition based on, admittedly small, differences from A. bebar females.

All specimens of A. reri were collected in PSF, either in seasonally wet formations or in areas around the Serkap River which are flooded whenever the Serkap rises above its banks.

Figures

FIGURES 1–3. Posterior pronotal lobe of Amphicnemis spp. in lateral view. (1) Amphicnemis annae male (SAR07_8_COE52, PSF in Simunjan area, Samarahan Division, Sarawak); (2) Amphicnemis reri sp. nov., holotype male; (3) Amphicnemis reri sp. nov., female described (RER23_COE40).

FIGURES 8–9. Anal appendages of males of Amphicnemis species, lateral views: (8) Amphicnemis annae (SAR05_COE182, PSF on Universiti Malaysia Sarawak campus, Samarahan Division, Sarawak); (9) sketch of Amphicnemis reri holotype.

FIGURES 10–11.Anal appendages of males of Amphicnemis species, dorsal views: (10) Amphicnemis annae (SAR05_COE182, PSF on Universiti Malaysia Sarawak campus, Samarahan Division, Sarawak); (11) sketch of Amphicnemis reri holotype.

FIGURES 4–5. Lateral view of penile organ of (4) Amphicnemis annae (SAR07_8_COE52, PSF in Simunjan area, Samarahan Division); (5) Amphicnemis wallacii (SAR11_12_COE421, PSF on Universiti Malaysia Sarawak campus, Samarahan Division, Sarawak).