Amphicnemis bebar Dow, Choong & Ng, 2010

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 : 275-276

Amphicnemis bebar Dow, Choong & Ng, 2010

( Figs 6, 7 )

Sumatran material examined. All from Kampar Peninsula, Pelalawan, Riau, Sumatra, Indonesia (arranged by location approximately from west to east), all sites in the range ca. 5–9 m a.s.l.: 1 ♂, 2 ♀♀ ( RER23 _COE180–182), PSF around Tasik Anggrek , Pelalawan Estate, 0.5027N, 102.1893E, 2 vi 2023, leg. R.A. Dow ; 1 ♂, 4 ♀♀ ( RER23 _ COE187–191), flooded PSF in Sungai Turip Riparian Buffer , 0.2921N, 102.6327E, 11 vi 2023, leg. R.A. Dow ; 6 ♂♂, 2 ♀♀ ( RER23 _COE16–22, 147), pools in PSF, Meranti Estate Block B Transect, 0.3363N, 102.6440E, 7 ii 2023, leg. R.A. Dow ; 3 ♂♂, 1 ♀ ( RER23 _COE183–186), same location, 8 vi 2023, leg. R.A. Dow ; 5 ♂♂, 2 ♀♀ ( RER20 _COE22–28), 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 ; 7 ♂♂, 4 ♀♀ ( RER20 _COE29–39), same location, 22 i 2020, leg. R.A. Dow ; 1 ♂, 1 ♀ ( RER20 _COE40–41), PSF (flooded by Sungai Serkap) between ranger post and Tasik Limau on Sungai Serkap , 0.3815N, 102.7154E, 26 i 2020, leg . R.A. Dow; 1 ♀ ( RER23 _COE290), flooded PSF beside Simpang Sianyir (tributary of Sungai Serkap) at 0.5137N, 102.5508, 1 x 2023, leg. R.A. Dow ; 1 ♂ ( RER23 _COE33), main trail in PSF from GHGFM tower, 0.3952N, 102.7646E, 13 ii 2023, leg. R.A. Dow ; 1 ♂ ( RER23 _COE34), shorter trail in PSF from GHGFM tower, 0.4006N, 102.7584E, 7 ii 2023, leg. RER staff ; 8 ♂♂, 5 ♀♀ ( RER23 _COE23–32, 45–46, 148), transect in PSF behind Sangar Pos (Sangar Ranger Post), Sungai Sangar, 0.3952N, 102.8421E, 9 ii 2023, leg. R.A. Dow ; 2 ♂♂ ( RER23 _COE192–193), same location, 17 vi 2023, leg. R.A. Dow.

Descriptive remarks. The Sumatran series agrees with the type series of A. bebar in details of, and variation in, colouration and markings. There is however rather extensive variation in the upper branch of the cercus seen laterally, with most individuals having the downturned apical part longer than in the holotype of A. bebar (see Fig. 18 in Dow et al. (2010) and Fig. 6 here), in some cases very much longer; this, together with differences in the female prothorax (see below) initially led the first author to believe that the Sumatran specimens were a separate species. However further investigation revealed a deficiency in the original description of A. bebar – there is actually variation in the cercus in the type series of A. bebar , with at least one paratype having the downturned apical part of the cercus longer than in the holotype ( Fig. 7 ) – the condition in the series from the Kampar Peninsula overlaps with that in the type series (similar variation occurs in the Singapore population of A. bebar ), so that they must be considered to belong to the same species. Nevertheless, the variation in the cerci of A. bebar is remarkable.

The posterior pronotal lobe of female A. bebar from the Kampar Peninsula is shallower than in the type series, sometimes not completely covering the mesostigmal area of the synthorax in lateral view, unlike the type series where this area is completely covered. There is variation in length in the central horn of the posterior pronotal lobe (as mentioned for the type series) and this horn is sometimes curved forward to some degree. The lateral pale spot on abdominal S9 is highly variable in size.

Measurements (mm). Males: abdomen plus anal appendages 33–36.5, Hw 18–19. Females: abdomen plus anal appendages and ovipositor 34–36.5, Hw 20.5–22.

Other Remarks. Amphicnemis bebar was found during all surveys conducted in the Kampar Peninsula and was found at more individual sites than either of the other two Amphicnemis species occurring in the peninsula. During the dry conditions of January 2020 the species was only found in PSF flooded by Sungai Serkap but during February/ March 2023 and June 2023 it was found at PSF sites that are not typically flooded when water levels in the rivers are high so that surface water is only present during parts of the year with high rainfall. In October 2023 (dry conditions) only a single female was found, in flooded forest around a tributary of Sungai Serkap. It appears likely that A. bebar occurs all year round at sites which are regularly flooded but only during rainy seasons at other sites within the PSF.

Figures

FIGURES 6–7. Variation in apical part of upper branch of cerci of Amphicnemis bebar males from the type series: (6) holotype; (7) paratype (PAH09_COE10).