The Odonata
of Binyo Penyilam, a unique tropical wetland area in Bintulu Division, Sarawak,
Malaysia
Rory A. Dow 1& Joanes Unggang 2
1 National Museum of Natural
History, P.O. Box 9517, 2300 RA Leiden, The Netherlands
2 Conservation Department,
Sarawak Planted Forests Department, Bintulu, Sarawak, Malaysia
Email: 1 rory.dow230@yahoo.co.uk (corresponding
author), 2 junis_sp@yahoo.com
Date of publication (online): 26 December 2010
Date of publication (print): 26 December 2010
ISSN 0974-7907 (online) | 0974-7893 (print)
Editor: Albert Orr
Manuscript details:
Ms
# o2478
Received
05 June 2010
Final
received 01 September 2010
Finally
accepted 10 October 2010
Citation: Dow, R.A. & J. Unggang (2010). The Odonata of Binyo Penyilam,
a unique tropical wetland area in Bintulu Division, Sarawak, Malaysia. Journal of Threatened Taxa 2(13): 1349-1358.
Copyright: © Rory A. Dow & Joanes Unggang 2010. Creative
Commons Attribution 3.0 Unported License. JoTT allows unrestricted use
of this article in any medium for non-profit purposes, reproduction and
distribution by providing adequate credit to the authors and the source of
publication.
Author Details: Rory A. Dow is a research associate at RMNH Naturalis, Leiden, where he is
employed in various digitisation projects. His research interests are in the
faunistics and taxonomy of Asian Odonata. He has extensive experience of
working in Southeast Asia, especially in Malaysian Borneo. Joanes
Unggang is head of the Conservation Department of Grand Perfect
Sendirian Berhad in the Sarawak Planted Forest Project. His background is in
botany and he has extensive experience of working in conservation in Sarawak.
Author Contribution: RAD identification of, and information on, the Odonata collected,
history of Odonata records from Bintulu division, photography. JU general information on BPCA and the SPFP area, information on
the habitats and flora of the BPCA, maps, photography.
Acknowledgements: The
first author would like to thank the Sarawak Forest Department and Sarawak
Forestry Corporation Sendirian Berhad for granting permission to collect
Odonata in Sarawak in 2006 and 2008. The management of Sarawak Planted Forest
Sendirian Berhad should be thanked for funding the field works in the project
areas. Graham Reels is thanked for allowing us to use one of his photographs.
We would also like to thank Mr. Rob Stuebing, formerly Conservation Officer of
Grand Perfect Sendirian Berhad, for originally inviting the first author to
sample at Binyo Penyilam, and all the staff (past and present) of the Sarawak
Planted Forest Project Conservation Department, and the people of Rumah Joseph
Ak Lapjit, who have assisted with fieldwork at Binyo Penyilam or with
organisation. Graham Reels and
Chee Yen Choong are thanked for their helpful reviews of the manuscript.
Abstract: Binyo Penyilam is a unique wetland conservation area within the
Sarawak Planted Forest Project zone in Sarawak’s Bintulu Division. A variety of forest and open habitats
are present in the area; these are characterised. An annotated list of 61 species of Odonata from 11 families
collected in the area to-date is presented. At least seven of these species had not been found in
Sarawak prior to their discovery at Binyo Penyilam, of these four – Pseudagrion coomansi, Merogomphus femoralis, Brachygonia puella and Chalybeothemis fluviatilis – have still not been found
elsewhere in the state; no other location is known for the genus Merogomphus in Borneo. Although under-sampling makes assessments
of the conservation status of south-east Asian Odonata
difficult, at least 16 of the species found at Binyo Penyilam can be considered
to be of potential conservation concern, at least within Sarawak.
Keywords: Bintulu, Binyo Penyilam, Borneo, conservation, Malaysia,
Odonata, Planted Forest Project, Sarawak.
Bahasa Malaysia Abstract: Binyo Penyilam adalah kawasan
konservasi tanah lembap yang unik di dalam zon Sarawak Planted Forest Project
di Daerah Bintulu, Sarawak. Pelbagai jenis hutan dan habitat terbuka yang
telah dikenalpasti terdapat di kawasan tersebut. Sehingga
ke hari ini 61 spesis Odonata dari 11 famili yang telah dikumpul di kawasan ini
telah disenaraikan di sini. Sekurang kurangnya tujuh daripada spesies
ini tidak pernah direkodkan di Sarawak sebelum penemuan nya di Binyo Penyilam,
daripada senarai itu empat spesies – Pseudagrion coomansi, Merogomphus femoralis, Brachygonia puella dan Chalybeothemis fluviatilis – masih belum dijumpai di
mana mana tempat di Sarawak; tidak ada lokasi lain pula yang diketahui untuk
genus Merogomphus di Borneo. Walaupun kekurangan penggumpulan sampel spesimen menyukarkan penilaian
untuk status konservasi Odonata di Asia Tenggara, sekurang kurangnya 16 spesies
yang terdapat di Binyo Penyilam itu boleh dianggap sebagai berpotensi untuk
diberi perhatian dari segi Konservasi sekurang kurangnya di dalam Sarawak.
For images & tables -- click here
Introduction
Historically there has been very
little collecting of Odonata (dragonflies and damselflies) in Sarawak’s Bintulu
Division. A few records had been
published prior to 2007 (Laidlaw 1915; Laidlaw 1920; Hincks 1930), with a total
of just 14 species recorded from the entire division. A number of publications dealing with Odonata and including
records from locations in Bintulu Division have appeared from 2007 onwards (Dow
et al. 2007; Dow 2008; Dow & Hämäläinen 2008; Dow & Reels 2010). A large part of Bintulu Division is now
included in the Sarawak Planted Forest Project (SPFP), formerly known as the
Planted Forest Zone. Here we
present records of Odonata from the Binyo Penyilam Conservation Area (BPCA), a
wetland area within the SPFP.
The SPFP (Image 1) lies within a gently
rolling landscape, situated northwest of a series of high, parallel ridges that
separate it from the Rejang River basin. It covers 490,000ha, of which 150,000ha have been identified as being
suitable for the establishment of forest plantations. 220,000ha are being retained as natural forest and managed
as reserves of various types. The
balance of 120,000ha is Native Customary Rights land. In the long term at least half of the entire area will
remain as natural forest, with two thirds of this protected.
A variety of vegetation types can
be found within the area, including lowland mixed dipterocarp forest, peat
swamps, limestone associations and kerangas forest, as well as Acacia mangium plantation. The SPFP Conservation Department has
been conducting plant inventories together with international and local
partners in Bintulu division, which had been poorly known floristically.
The BPCA (Image 1) is situated in
the eastern central SPFP, and consists of kerangas forest, peat dome forest and
peat swamp “lakes”, and has a total area of 15,300ha. It is a mosaic of partially disturbed and original swamp
forest that has developed over a deep inland basin. Details of vertebrate groups found in the BPCA can be found
in Stuebing et al. (2007). The
vegetation of the BPCA is mainly influenced by the permanently and
semi-permanently flooded nature of the area. The poor drainage of the area has led to the formation of an
unusual type of peat dome forest, creating unique padang communities of stunted
trees and grasses and black water lakes. Within the permanently flooded area there are peat dome forests of Alan
(Shorea
albida) and Ramin (Gonystylus bancanus and G. maingayi). Some small clumps of higher ground surrounded by the swamps
and small lakes are mostly dominated by dipterocarps and gymnosperm species.
About 150 species of ferns and
fern-allies and flowering plants have been collected and identified in the BPCA
to-date (Demies et al. 2006). Trees and shrubs are well represented by 67 species, orchids with 25
species, ferns and fern-allies with 15 species. Four palm species and two species from the Cyperaceae, a
grass family, have been found. The
Araceae (aroids) is represented by five species, and at least five climber
species have been found. Elements of the deep peat swamp flora (i.e. species that only grow
on peat domes) are represented by two species of Gonystylus, one from the Bombaxaceae, one aroid
and two Pandanusspecies. Padang
communities are dominated by grasses such as Cyperaceae, and carnivorous plants
such as Nepenthes. Nepenthes species are rich in the marsh areas and around the lakes, seven
species have been recorded (Unggang 2007), of which N. bicalcarata and N. albomarginata are Bornean endemics. Another
unusual plant of the BPCA is a fern, Trichomanes singaporeanum, that until recently had only been found growing on mountain
ridges.
Sampling of Odonata has been
conducted in most of the habitat types stated above except the lake areas, but
only a small part of Binyo Penyilam has been sampled to-date. Sixty-one species
of Odonata have been found in the area so far. This total is certain to rise with further sampling, but
already includes a relatively high proportion of species that can be considered
as rare and/or poorly known, and several first records for Sarawak and, in some
cases, Borneo.
Material
and Methods
To-date only sampling of adult
Odonata has taken place within Binyo Penyilam. Collecting has been conducted using hand-held nets, and has
taken place on foot, or when this was not possible, from boats. Collecting was
carried out on 8-11 March in 2006, and on 26-29 January and 5-10 October in2008. At each location sampled the aim
was to collect at least one specimen of each species present. In cases where species are difficult to
distinguish in the field, or of particular interest, an effort was made to take
longer series of specimens. However, many adult odonates are difficult to capture, hence not every
species encountered was successfully collected. Conversely, little effort was made to capture more than a
single voucher specimen for common and widely distributed species that are
easily identified in the field. Most of the material collected is currently held in the collection of
the first author, with duplicates to be placed in the Sarawak Forest Research
Centre.
Collecting was carried out at
the locations listed below:
(1) The Sg. Penyilam. This stream, a tributary of the Sg.
Binyo, naturally has the characteristic clear dark water of peat swamps,
indicating very little sediment input. It ran clear when sampled in 2006, but was turbid during sampling in
2008. The downstream part of the
stream flows through a generally wide and regularly flooded area with extensive
stands of Pandanus andersonii, with some much narrower areas (Image 3), with the more open
areas often lined with Donax sp.
(Image 4); the upstream part to the furthest point sampled flows through
disturbed low pH swamp forest (Image 5). Sampling has been conducted between the locations marked as “Field
Station” and “Upstream” in Image 2.
(2) Swamp forest (Image 6) around
the Sg. Penyilam and small hillocks arising from the swamp. Sampling was carried out at a number of
individual sites along the Sg. Penyilam.
(3) Open flooded areas at the
landward margins of the large Pandanus andersonii areas in the lower part of the Sg. Penyilam.
(4) Open meadows, black water
marshes and lagoons (Images 7-8), marked as “Location 4” in Image 2.
(5) A tributary to the Sg. Binyo,
upstream and on the opposite shore to the Sg. Penyilam, in disturbed forest,
marked as “Location 5” in Image 2.
(6) The Sg. Binyo, a turbid river.
(7) At the SPFP Conservation
Department field station, “Field Station” in Image 2.
(8) Rumah Joseph, an Iban longhouse
on the Sg. Binyo, close to the mouth of Sg. Penyilam.
Collecting was carried out by the
first author and the following members of the SPFP Conservation staff: in March
2006 by Azizan Juhin and Stephen Stone, in January 2008 by Roslina Ragai, and
in October 2008 by Jimmy Teo and Tony Chaong.
Results
The following is a list of all
species collected at Binyo Penyilam to-date. For each species a list of material, brief notes and a list
of locations where they were collected are given. The family level taxonomy
used here follows that in Orr (2003).
Zygoptera
Chlorocyphidae
(i) Libellago aurantiaca Selys, 1859 – Moderately
common on the upstream Sg. Penyilam. Location 1: 2 males, 11.iii.2006; 1 male, 28.i.2008.
(ii) Libellago hyalina Selys, 1859 – A common
species, especially on streams in swamp forest; it is often extremely abundant
on the Sg. Penyilam. Locations 1, 2, 5: 3 males, 3 females, 8-10.iii.2006; 4 males,
26-29.i.2008; 4 males, 5-9.x.2008.
(iii) Libellago orriDow & Hämäläinen, 2008 – A recently described species (Dow & Hämäläinen
2008), so far only known from Bintulu division, where all the known sites are
within the PFZ. This species is
allied to L. hyalina, and although the males are easily separable by colouration, the
females of the two species are almost identical. Abundant on
parts of the Sg. Penyilam. Only material not included in the type series is listed here. Location 1: 10 males, 26-29.i.2008; 2
males, 5-8.x.2008.
Euphaeidae
(i) Dysphaea dimidiata (Selys, 1853) – Usually a
species of larger streams and rivers, not common at Binyo Penyilam. Location 1: 1 male, 9.iii.2006.
Calopterygidae
(i) Vestalis amabilis Lieftinck, 1965 – In March
2006 when the Sg. Penyilam still ran clear this species was common on the
upstream part, but on subsequent visits it was much scarcer; it is unclear
whether this is the result of the increased turbidity or of natural population
fluctuations, or of some other factor not apparent to the authors. In Sarawak this species is most often
encountered on streams in swamp forest or kerangas areas. Locations
1, 2: 11 males, 1 female, 8-11.iii.2006; 4 males, 27-28.i.2008; 1 male,
6.x.2008.
Megapodagrionidae
(i) Podolestes orientalis Selys, 1862 – A common
species in swampy lowland forest. Location 2: 1 male,
8.iii.2006; 2 males, 29.i.2008; 1 male, 8.x.2008.
Protoneuridae
(i) Elattoneura aurantiaca (Selys, 1886) – In Sarawak
this species appears to be confined to streams in swamp forest (usually peat
swamp); it has been abundant on the Sg. Penyilam during all sampling periods
to-date (Image 9). Locations 1, 2,
5: 20 males, 3 females, 8-11.iii.2006; 16 males, 5 females, 26-29.i.2008; 4
males, 2 females, 5-9.x.2008.
(ii) Elattoneura longispina Lieftinck, 1937 - This species,
remarkable for the structure of its anal appendages, has not been recorded from
Sarawak previously. It is
otherwise known from north-west and south-east
Kalimantan and Belitung (formerly Billiton) island (Lieftinck 1954). It occurs very locally in swamp forest
at Binyo Penyilam, and has also been found at another location in Bintulu
Division. It has yet to be found
elsewhere in East Malaysia. Locations 2, 10: 1 male, 8.iii.2006; 6 males, 2 females,
27-29.i.2008.
(iii) Prodasineura verticalis (Selys, 1860) – A common
stream and river species, but only occurring at low densities at Binyo
Penyilam. It favours streams with
an open canopy. Locations 1, 6: 1 male, 26.i.2008; 3 males, 6-9.x.2008.
Coenagrionidae
(i) Aciagrion borneense Ris, 1911 – A moderately
common, and easily overlooked species, typically found on shallow grassy pools
in open habitats. Location 4: 1 male, 1 female, 10.iii.2006; 1 female, 7.x.2008.
(ii) Agriocnemis femina (Brauer, 1868) – A very
common species in open lentic habitats, but to-date only one female has been
collected at Binyo Penyilam. Location 1: 1 female, 29.i.2008.
(iii) Amphicnemis annae Lieftinck, 1940 – A
moderately uncommon species of peat swamp and other low pH swamp forest. Location 2: 5 males, 1 female,
8-9.iii.2006; 1 male, 1 female, 8.x.2008.
(iv) Amphicnemis sp. cf. dactylostyla Lieftinck, 1953 – This
problematic form is commoner at Binyo Penyilam than the last species, and
appears to be distributed across Sarawak from the west to Loagan Bunut National
Park in the north-east. It is
clearly closely allied to dactylostyla, but determination of its true status will have to await a
revision of the genus in Borneo. It is also closely related to A. martini Ris, 1911, but appears to be distinct from that species, which in
Sarawak has only been found recently in Gunung Mulu National Park. All records
of A.
martini in
Sarawak from
west of Gunung Mulu National Park appear to actually refer to this
form/species. It is usually, but
not always, found in peatswamp forest; like the last species it is very local
in its occurrence at Binyo Penyilam. Location 2: 5 males, 3 females, 9-10.iii.2006; 4 males, 11 females,
27-28.iii.2008.
(v) Amphicnemis sp. cf. gracilis Krüger, 1898 – An even more
problematic form than the last; it has similarities with A. gracilis, A. billitonis Lieftinck, 1940 and A. wallacii Selys, 1863. Although in the structure of its terminal appendages the male is most
similar to A. gracilis, it
is possible that it and forms found further east in Sarawak are all merely
local variants of A. wallacii. Abundant
in swamp at Binyo Penyilam and known from other locations in Bintulu Division. Location 2: 3 males, 2 females,
8-10.iii.2006; 14 males, 13 females, 27-28.i.2008; 2 males, 3 females,
8.x.2008.
(vi) Archibasis incisura Lieftinck, 1949 – This is
not generally a common species in Sarawak, but appears to be quite abundant on
the Sg. Penyilam, and may favour low pH forest streams. Locations 1, 5: 2
males, 1 female, 9.iii.2006; 6 males, 2 females, 26-29.i.2008; 7 males,
5-9.x.2008.
(vii) Archibasis melanocyana (Selys, 1877) – In the
authors experience this is not a common species in Sarawak, although it is
common in Brunei (Orr 2001), but it is sometimes abundant on the Sg. Penyilam.
Locations 1, 3, 4 (two females were taken at a pool at this location): 20
males, 4 females, 9-11.iii.2006; 5 males, 26-29.i.2008.
(viii) Archibasis tenella Lieftinck, 1949 – This
species is normally commoner than the preceding two in Sarawak, and occurs on a
larger range of stream types; however at Binyo Penyilam only a single teneral
(freshly emerged) specimen has been collected. Location 1: 1 male, 10.iii.2006.
(ix) Archibasis viola Lieftinck, 1948 – The
commonest member of the genus in Sarawak. Locations 1, 2, 5: 3 males, 1 female,
8-11.iii.2006; 2 males, 27-28.i.2008; 3 males, 1 female, 6-9.x.2008.
(x) Ceriagrion cerinorubellum (Brauer, 1865) – A very
common species, especially in open and disturbed habitats. Locations
1, 4: 2 males, 9-10.iii.2006; 1 male, 29.i.2008.
(xi) Mortonagrion falcatum Lieftinck, 1934 – A single female was collected at the edge
of a blackwater pool in the open marshland area. M. falcatum has a wide distribution in
Sundaland, but had not been recorded in Sarawak prior to 2006, when it was also
collected in Gunung Mulu National Park (Dow & Reels 2008). However it has been recorded in Brunei
(Orr 2001) and is easily overlooked on account of its small size, so is likely
to be under-recorded in Sarawak. Location 4: 1 female, 10.iii.2006.
(xii) Mortonagrion new sp. – This small, dark
species was first discovered in peatswamp forest on the UNIMAS campus at Kota
Samarahan in 2005; it has subsequently been found at a number of low pH forest
locations in Sarawak, and is locally common at Binyo Penyilam. A description is
in preparation by the first author. Location 2: 1 male, 1 female, 8-10.iii.2006; 9 males, 7 females,
27-28.i.2008; 6 males, 1 female, 8.x.2008.
(xiii) Pseudagrion coomansi Lieftinck, 1937 – apart from
one old and questionable record of a female (Lieftinck 1954) this is the first
record of this species from East Malaysia. It is moderately common in the open marshland at Binyo
Penyilam, where it is found flying over black water pools. Location 4: 4 males,
1 female, 10.iii.2006; 3 males, 7.x.2008.
Platycnemididae
(i) Copera vittata (Selys, 1863) – This is a
widespread species in tropical and subtropical Asia, with a confusing variety
of named subspecies, and still more unnamed forms. The typical form in Borneo
has red legs, but a form with yellowish legs exists in western Sarawak, a form
with black legs exists in Brunei (Orr 2001, 2003) and a form with yellow and
black legs is found in Bintulu Division. The determination of the true status
of these forms awaits a thorough revision of the genus. Locations
2, 5: 1 female, 11.iii.2006; 1 male, 9.x.2008.
Anisoptera
Gomphidae
(i) Ictinogomphus acutus (Laidlaw, 1914) – This
species appears to be a specialist found in low pH habitats. It is classified as Near Threatened in
the IUCN Red List (IUCN 2010). It is
usually common on the Sg. Penyilam, but the first author has found it at only
one other location in Sarawak: Loagan Bunut (Dow & Reels 2006) (Image
10). Locations
1, 3, 6: 7 males, 9-11.iii.2006; 6 males, 3 females, 26-29.i.2008; 3 males, 2
females, 5-9.x.2008.
(ii) Ictinogomphus decoratus
melaenops(Selys, 1858) – The commonest member of the Gomphidae in Sarawak, found
on open lentic and slowly flowing waters. Location 1: 1 male, 29.i.2008.
(iii) Macrogomphus
parallelogramma albardae (Selys, 1878) – This species has not previously been
recorded from Sarawak, it appeared to be moderately common on the Sg. Penyilam
in March 2006, but has not been found there subsequently. One male was captured while foraging at
the streams edge at dusk; records of crepuscular (dusk and evening) flight in
this family are scarce; but the first author has subsequently observed similar
behaviour from this species at Bukit Sarang (also in Bintulu Division). Wilson (2008) recorded crepuscular
activity in Orientogomphus minor (Laidlaw, 1931) in Thailand, so perhaps dusk and evening flight
in the Gomphidae is more common than has been supposed. Location 1: 3 males, 1 female,
8-11.iii.2006.
(iv) Macrogomphus quadratus (Selys, 1878) – A
distinctively marked species, the commonest of its genus in Sarawak, found on a
variety of forest streams. Location
1: 3 males, 9-11.iii.2006; 4 males, 28-29.i.2008.
(v) Merogomphus femoralis Laidlaw, 1931 – This is the first record of a Merogomphus species from Borneo; the Sg.
Penyilam remains the only site known on the island for the genus. M. femoralis was previously only known from the
holotype, taken in west Malaysia, but a photographic record probably of this
species was recently made in Singapore (Cheong et al. 2009). Location 1: 3 males, 1 female,
9-11.iii.2006; 2 males, 6.x.2008.
(vi) Microgomphus sp. – A single teneral
female was collected on the Sg. Penyilam. The only species of the genus so far recorded from Borneo is M. chelifer (Selys, 1858), but as the adults
of Microgomphus species are very elusive, there
could well be additional species present on the island. As the specimen is in poor condition,
it is not possible to come to any firm conclusion regarding its status.
Location 1: 1 female, 11.iii.2006.
Aeshnidae
(i) Gynacantha basiguttata Selys, 1882 – Likely to be
quite common in Sarawak, but not many records have been made in the state
to-date. The single specimen
collected at Binyo Penyilam was foraging during rain in the late
afternoon. Location 7: 1 male, 7.x.2008.
(ii) Gynacantha dohrniKrüger, 1899 – This is the most frequently collected Gynacantha species in Sarawak, often coming
to lights at buildings near to lowland forest. Locations 2,
7, 8: 1 male, 1 female, 10-11.iii.2006; 5 males, 1 female, 5-8.x.2008.
(iii) Gynacantha species – A female collected
at Rumah Joseph in 2008 is not G. basigutatta or G. dohrni, but it has not been possible to identify it to species. Location
8: 1 female, 26.i.2008.
Corduliidae
(i) Hemicordulia tenera Lieftinck, 1930 – A fast
flying species, in Sarawak seemingly confined to swampy forest areas and very
local in occurrence. Sometimes quite common on the Sg.
Penyilam where males patrol sections of the stream. Location 1: 2 males,
9-10.iii.2006; 3 males, 5-8.x.2009.
(ii) Macromia arachnomima Lieftinck, 1953 – The
exuviae of the distinctive long legged larvae of this species were found in
large numbers on the Sg. Penyilam in January 2008. All records from Sarawak are
of larvae or exuviae, with the first record of the species in the state being
made at Gunung Mulu National Park earlier in January 2008 (Dow & Reels 2009).
Location 1.
(iii) Macromia cincta Rambur, 1842 – The commonestMacromia species in Sarawak, abundant on
the Sg. Penyilam. Location 1: 6 males, 9-11.iii.2006; 2 males, 26-29.i.2008; 7
males, 1 female, 5-8.x.2008.
Libellulidae
(i) Brachygonia oculata (Brauer, 1878) – A common
species of swamp habitats. Locations 1, 2: 2 males,
8.iii.2006; 2 males, 26-28.i.2008; 1 male, 2 females, 5-9.x.2008.
(ii) Brachygonia puella Lieftinck, 1937 – This is
the first record of this small species from Sarawak; it is otherwise only known
from Belitung and south Kalimantan (e.g. Lieftinck 1954). It is common in parts
of the open marsh land at Binyo Penyilam. Image 11.
Locations 1, 2, 4: 10 males, 7 females, 10.iii.2006; 3 males, 3 females,
27-29.i.2008; 4 males, 1 female, 7-8.x.2008.
(iii) Chalybeothemis fluviatilis Lieftinck, 1933 – Apparently
an extremely local and specialised species, confined to low pH habitats. First
recorded from Sarawak at Binyo Penyilam (Dow et al. 2007), and still not
recorded elsewhere in the state. It is moderately common at ponds in the open marsh land at Binyo Penyilam and sometimes occurs on the
open parts of the Sg. Penyilam. Locations 1, 4: 1 male,
26.i.2008; 6 males, 5-8.x.2008.
(iv) Cratilla metallica (Brauer, 1878) – A common
species on pools in lowland forest, but at Binyo Penyilam just two females have
been collected, perched high over the Sg. Penyilam, an unusual location for the
species. Location 1: 2 females, 9-11.iii.2006.
(v) Nannophya pygmaea Rambur, 1842 – A common
species of marshlands and shallow ponds, sometimes also found on streams.
Locations 1, 4: 7 males, 2 females, 8-10.iii.2006; 1 male, 1 female,
28-29.i.2008; 3 males, 6-7.x.2008.
(vi) Nannophyopsis chalcosoma Lieftinck, 1935 – A very
poorly known species, not recorded in Sarawak since 1953 (Lieftinck 1953),
until it was rediscovered at Binyo Penyilam in January 2008, where it was found
in one section of flooded forest bordering the Sg. Penyilam. Several males and
one female were observed, although it was only possible to collect one male.
Males appeared to prefer low perches, and were extremely inconspicuous.
Location 2: 1 male, 29.i.2008.
(vii) Nesoxenia lineata (Selys, 1879) – A widespread
species, but local in occurrence, found in swampy forest habitats and seldom
common. Locations 1, 3: 2 males, 2 females, 29.i.2008; 1
male, 9.x.2008.
(viii) Neurothemis fluctuans (Fabricius, 1793) – An
extremely common species in Sarawak, especially in open disturbed habitats. Locations 3, 4: 1 male, 10.iii.2006; 2 males, 29.i.2008; 1 male,
7.x.2008.
(ix) Onychothemis culminicola Förster, 1904 – A riverine
species first recorded in Sarawak in 2006 (e.g. Dow & Reels 2008); an
earlier record of O. c. celebensis Ris, 1912 (Laidlaw 1920) actually referred to O. coccinea Lieftinck, 1953 (Lieftinck 1954). Probably rather common in Sarawak, but wary and fast flying, hence
under-recorded in the state. Location 1: 1 female, 6.x.2008.
(x) Orchithemis pruinans (Selys, 1878) – A very local
species in Sarawak, but quite common at Binyo Penyilam. Locations
1, 2: 1 female, 8.iii.2006; 3 males, 3 females, 5.x.2008.
(xi) Orchithemis pulcherrima Brauer, 1878 – A very common
species in swamps and marshes, abundant at Binyo Penyilam. Locations 1, 2, 4,
5, 7: 3 males, 8 females, 8-11.iii.2006; 3 males, 3 females, 26-28.i.2008; 4
males, 2 females, 5-9.x.2008.
(xii) Orchithemis xanthosoma Laidlaw, 1911 – A species
that is regarded as rare, but appears to be moderately common at Binyo
Penyilam. The first author has found this species at a number of locations
across Sarawak since 2006, always in association with low pH swamp forest.
Image 12. Locations 1, 2: 5 males, 1 female, 8-10.iii.2006; 2 males, 4 females,
27-28.i.2008; 1 male, 6.x.2008.
(xiii) Orthetrum chrysis (Selys, 1891) – A common
species found in a variety of lotic and lentic habitats. Locations
1, 4, 8: 1 male, 1 female, 9-11.iii.2006; 1 male, 7.x.2008.
(xiv) Orthetrum sabina (Drury, 1773) – A very
common species, usually found in disturbed habitats. Location
1, 3, 4: 2 males, 10.iii.2006; 1 male, 29.i.2008; 1 male, 6.x.2008.
(xv) Orthetrum testaceum (Burmeister, 1839) – Another
very common species usually found in disturbed habitats. Location 1: 1 male,
11.iii.2006.
(xvi) Pornothemis serrata Krüger, 1902 – A specialist
swamp forest species. Males are sometimes found guarding small pools, and at
Binyo Penyilam also occasionally on the Sg. Penyilam. Locations
1, 2: 2 males, 28.i.2008; 1 male, 2 females, 5-6.x.2008.
(xvii) Raphismia inermis Ris, 1910 – Seemingly a very
rare species. A single male was captured at camp lights at Binyo Penyilam one
evening in March 2006 and another in shade near one of the ponds in an open
marsh area in October 2008. The author is aware of no other recent record from
Sarawak, and only one historical record (Laidlaw 1920). Locations
2, 4: 1 male, 8.iii.2006; 1 male, 8.x.2008.
(xviii) Rhodothemis rufa (Rambur, 1842) – A common
species in open habitats. Location 1: 1 female, 9.iii.2006.
(xix) Rhyothemis aterrima Selys, 1891 – A local
species, but common at Binyo Penyilam. Locations 1, 4: 3
males, 26-27.i.2008; 3 males, 5-7.x.2008.
(xx) Rhyothemis obsolescens Kirby, 1889 – Common at
Binyo Penyilam. Locations 1, 2, 3, 4, 5: 7 males, 3 females,
8-11.iii.2006; 4 males, 2 females, 25-29.i.2008; 7 males, 7-9.x.2008.
(xxi) Rhyothemis pygmaea (Brauer, 1867) – The least
common and most local of the Rhyothemis species occurring in Sarawak. Locations 1, 2,
4: 1 male, 10.iii.2006; 1 female, 27.i.2008; 1 female, 8.x.2008.
(xxii) Tramea phaeoneura Lieftinck, 1953 – A local
species of open standing water habitats; probably under-recorded due to its
similarity with the widespread and common Tramea transmarine euryale Selys, 1878. Location 4: 2 males, 10.iii.2006;
2 males, 7.x.2008.
(xxiii) Tyriobapta laidlawi Ris, 1919 – A local species,
most often found in low pH swamp forest. Location 2: 2 males,
8-11.iii.2006; 3 males, 3 females, 27.i.2008; 3 males, 8.x.2008.
(xxiv) Tyriobapta torrida Kirby, 1889 – Generally the
commonest Tyriobapta species in lowland forest in Sarawak, but less common in swamp
forest. Locations 2, 5: 2 males, 6-8.iii.2006; 1 male,
9.x.2008.
(xxv) Urothemis signata insignata (Selys, 1872) – A common,
widespread species, abundant on the more open parts of the Sg. Penyilam.
Locations 1, 3, 4: 3 males, 1 female, 9-10.iii.2006; 4 males, 1 female,
26-29.i.2008; 1 male, 5.x.2008.
(xxvi) Zyxomma petiolatum Rambur, 1842 – A common
crepuscular species. Location 8: 1 male, 1 female, 26.i.2008.
Discussion
As a large area consisting mainly
of low pH swamp forest (albeit disturbed) mixed with naturally open habitats,
Binyo Penyilam is an exceptionally interesting area for Odonata in
Sarawak. A number of the habitats
at Binyo Penyilam are unusual and may not be represented in totally protected
areas in Sarawak. Low pH swamp
forest is relatively poorly represented in Sarawak’s currently gazetted
protected areas (compared, for instance, to hill-side mixed dipterocarp
forest), but provides a habitat for a number of specialist species. Natural
open habitats are scarce in Sarawak, and the open marsh areas at Binyo Penyilam
appear to offer suitable habitat for some species not found elsewhere in the
state.
At least seven species (Libellago orri, Elattoneura longispina, Pseudagrion coomansi, Macrogomphus parallelogramma albardae, Merogomphus femoralis, Brachygona puella and Chalybeothemis fluviatilis) not definitely recorded in Sarawak prior to 2006 have been found
at Binyo Penyilam, a high number for a single area; four of these species have
still not been found elsewhere in the state (P. coomansi, M. femoralis, B. puella and C. fluviatilis). The Sg. Penyilam
remains the only known site for a Merogomphus species on Borneo. Two other species collected in this area have not been recorded anywhere
else in Sarawak for decades, these are the apparently very rare Nannophyopsis chalcosoma and Raphismia inermis.
Because of under-sampling it is
generally difficult to assess the conservation status of Odonata in south-east Asia. However 16 of the species found at Binyo Penyilam can be considered to
be of potential conservation concern, at least within Sarawak. These species are listed in Table 1,
together with a brief justification for their inclusion.
A number of the species listed in
Table 1 (Mortonagrion falcatum, Ictinogomphus acutus, Hemicordulia tenera, Chalybeothemis fluviatilis, Nannophyopsis chalcosoma, Rhyothemis pygmaea, Tramea phaeoneura) have also been recorded in Brunei, but all are very localised
there and in many cases their habitats are at risk (Orr 2001; pers. comm.).
Odonate diversity in lowland swamp
and marshland habitats in Borneo is not as high as in mixed dipterocarp forest
(Orr 2006). That said, diversity
at Binyo Penyilam is relatively high, with 61 species from 11 families of
Odonata recorded. Most of the
collecting effort to-date has been concentrated on the Sg. Penyilam, or in the
open marshland; relatively little time has been spent within the swamp forest
areas, it is likely that more collecting here would result in a significant
increase in the number of species recorded in the area. The lakes present in the area, not
sampled for Odonata yet, are also likely to yield additional species.
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