Two new localities of
Sri Lankan Relict Ant Aneuretus simoniEmery, 1893 (Formicidae: Aneuretinae)
with the very first record in the intermediate zone
D.A.G.N.B. Karunarathna 1 & W.A.I.P. Karunaratne 2
1,2 Department of Zoology,
Faculty of Science, University of Peradeniya, Peradeniya 20400, Sri Lanka
1 nuwan_bk@yahoo.com, 2 inokap@pdn.ac.lk (corresponding
author)
doi: http://dx.doi.org/10.11609/JoTT.o3334.4604-7 | ZooBank:urn:lsid:zoobank.org:pub:5FFAB328-7102-46FA-9F31-E1CF2AB9A848
Editor: Brian Fisher, California
Academy of Sciences, USA. Date
of publication: 26 July 2013 (online & print)
Manuscript details: Ms #
o3334 | Received 04 September 2012 | Final received 07 June 2013 | Finally
accepted 22 June 2013
Citation: Karunarathna,
D.A.G.N.B. & W.A.I.P. Karunaratne (2013). Two new localities of Sri Lankan Relict Ant Aneuretus simoni Emery, 1893 (Formicidae:Aneuretinae) with the very first record in the
intermediate zone. Journal of Threatened Taxa 5(11): 4604–4607; http://dx.doi.org/10.11609/JoTT.o3334.4604-7
Copyright: © Karunarathna& Karunaratne 2013. Creative
Commons Attribution 3.0 Unported License. JoTT allows unrestricted use of this article in any medium,
reproduction and distribution by providing adequate credit to the authors and
the source of publication.
Funding: This study was self-funded by
authors.
Competing Interest: None.
Acknowledgements: Authors
thank Forest Department of Sri Lanka (permit no. R&E/RES/NFSRC/11) and
Department of Wildlife Conservation (permit no. WL/3/2/1/7) for permitting
access and specimens collection from the Knuckles Forest Reserve; to Divisional
Secretary, Panwila for granting permission to work inMoraella forest (permit no. PV/A/5/3/01/II). We are
grateful to Prof. J.P. Edirisinghe for accommodating
us with their field visits. We thank Mr. M.P. Ranaweerafor guiding us in Moraella forest, and Mr. N. Wijayathilaka for photographing specimens. Dr. A.S.T.B. Wijetunga is acknowledged for his clarification on the
vegetation types of the selected habitats. Field assistance given by P.G.N.J. Bandara, G.W.B. Ellepola, G.C.P. Diyes and Y. Edirisinghe is
highly acknowledged.
For figure, image -- click here
Aneuretus is the only living genus of
the tribe Aneuretini (Formicidae:Aneuretinae), with all other genera (Aneuretellus, Protaneuretus,Paraneuretus and Mianeuretus)being extinct (Bolton 1994). The only extant Aneuretusspecies is A. simoni (Sri Lankan Relict Ant)
(Image 1), an endemic to Sri Lanka (Wilson et al. 1956; Jayasuriya& Traniello 1985) that is classified as
Critically Endangered by the IUCN, mainly due to its limited distribution
(Social Insects Specialist group 1996). Earlier, the phylogenetic position of A. simoniwas thought to be intermediate between primitive and advanced subfamilies of
ants (Wilson et al. 1956), but recent studies have shown that it is the nearest
living relative of subfamily Dolichoderinae (Brady et
al. 2006; Ward et al. 2010). Thus A.simoni has played a major role in understanding
the evolution of Dolichoderinae (Ward et al. 2010).
Aneuretus simoni was first described (Emery
1893) based on a collection made in 1892 from Kandy. However, until 1955 it was known only
from a few specimens in museum collections worldwide. In 1955, adult and larval morphology of A.simoni together with its distribution and ecology
were studied by a group of scientists who visited Sri Lanka (Wilson et al.1956). According to Wilson et al.
(1956), A. simoni was distributed in five
localities, namely Ratnapura, Gilimale,
Adam’s Peak, Peradeniya and Kandy in the wet zone of
Sri Lanka (Fig. 1). Later, in 1979,Jayasuriya & Traniello(1985) conducted a survey in Sri Lanka to study the distribution, abundance and
foraging behavior of A. simoni. After surveying several localities,
including locations from which this ant was previously recorded, A. simoni was collected only from GilimaleForest Reserve (a lowland rain forest; average elevation 152m) in the Ratnapura District.
Recent investigations have
resulted in the discovery of A. simoni from Pompekelle, a secondary forest in the RatnapuraDistrict (Chaminda & Dias 2001; Dias 2004) and
again from Gilimale in 2004 (Dias 2008). This species was also recorded from Sinharaja Forest Reserve (a lowland rain forest extending
into Ratnapura, Kalutaraand Matara districts), in 2005 by Pereraet al. (2006) and during the period from 2005–2007 by Gunawardeneet al. (2008). In 2009 A. simoni was discovered from ‘Kirikanda’,
a lowland rain forest habitat in the KalutaraDistrict located very close to the Sinharaja boundary
(Dias et al. 2011) (Fig. 1).
Up until this current study A.simoni was recorded only from forests of the
island’s wet zone, where mean annual rainfall is >2,500mm. Hence the persistence of lowland rain
forest conditions (higher rainfall and low elevations) of the wet zone of Sri
Lanka has permitted the continued survival of this species. However, during an ongoing study of ants
in the central part of Sri Lanka, this rare ant was discovered from two new
localities, extending its range within the wet zone and into the intermediate
zone of the island.
Materials and Methods: Field work was conducted from October
2011 to March 2012 to investigate the species composition of litter ant fauna
in the Knuckles Mountain Range, which spans mainly the intermediate zone of Sri
Lanka (Bambaradeniya & Ekanayake2003). Two sites were surveyed for
ants, the lowland rainforest in Moraella, in the wet
zone and the semi-evergreen forest of Rambukoluwa in
the intermediate zone (Fig. 1). Moraella forest (7021’50.67”N
& 80044’5.91”E) is a recently discovered fragmented wet lowland
rain forest at 500–700 m elevation in the valley of Kukul Oya (oya=stream) in the
southwestern foothills of Knuckles Range. Of the 204 plant species discovered in Moraellaforest, 89 are endemic to Sri Lanka while 39 are nationally threatened (Medawatte et al. 2011). The vegetation is mainly comprised of
trees of the family Dipterocarpaceae such as Dipterocarpus zeylanicus,Shorea dyeriand Vateria copallifera(Medawatte et al. 2011). The forest is situated in the Panwila Division in Kandy District within an area receiving
a mean annual rainfall of 2500–3000 mm (National Atlas 1988).
The second field site was
located in a well established forest in Rambukoluwa(7032’54.56”N & 80047’28.79”E)
below 700m elevation in the Matale District. The major natural vegetation type in the
lower elevation of the Knuckles Mountain Range is semi-evergreen forests that harbour many large
trees that shed their leaves during the long dry and windy season from July to
August. The forest consists of
three strata: canopy (20–25 m), sub-canopy (15–10 m) and scanty ground
herbaceous vegetation (Bambaradeniya & Ekanayake 2003). Mean annual rainfall of the area is >2000mm (National Atlas 2007).
Three 100m transects were
laid out in each forest type and the ants were collected in twelve 1x1 m
quadrats along each transect using
two established methods: Winkler extraction and hand collection. In six quadrats ants were hand collected
for three hours by two people, while in the other six ants were extracted using
the Mini-Winkler method (Bestelmeyer et al.
2000). Additionally, ants were
collected randomly outside the transect using
forceps. Collected ants were
preserved in 70% alcohol and voucher specimens were deposited in Invertebrate
Systematics and Diversity Facility at Department of Zoology, University of Peradeniya.
Results and Discussion: A total of 155 Aneuretus simoni workers were
collected from four quadrats along one transect (average elevation 592m) in theMoraella forest (relative abundance 1%) and from
three quadrats along two transects (average elevation 549m) in the semi
evergreen forest (relative abundance 2.6%). Relative abundance of A. simoni along the transect laid
in the Moraella forest and in the two transects laid
in the semi evergreen forest were 6%, 3.8% and 2.5% respectively. From all the transects,
hand collection yielded only 13 A. simoniworkers, and the rest of the individuals (92%) were collected using Winkler
extraction method.
Random collections made in
semi-evergreen forest revealed that A. simoni is
an inhabitant of forest edges. Despite its rarity, this is unsurprising as Wilson et al. (1956) have
reported this ant as being abundantly present at forest edges, even at edges of
clearings. This collection in
semi-evergreen forest supports the fact that A. simoni is adapted to forest clearings and it does not require deep rain forest
conditions for survival (Wilson et al. 1956). However, rainfall seems to be an
important factor for the distribution of this species. Mean annual rainfall of the two new
localities is >2,000mm supporting the previous findings that the rainfall
range of 2,000–5,000 mm favours distribution ofA. simoni (Jayasuriya& Traniello 1985). The fact that A. simonihas been recorded from Udawattakele Sanctuary in
Kandy, a noticeably drier forest than forests in Ratnapuraarea (Wilson et al. 1956), and its discovery from semi-evergreen forests, which
experience a long dry spell and desiccating winds during July–August, may
suggest that A. simoni has some adaptations to
drier conditions as well, and hence can be expected from drier habitats. Studies carried out in Kahalla-Pallekele forest, Dambullaand Anuradhapura sanctuary in the dry zone of Sri Lanka, however, have not
recorded this species so far (Dias & Peiris 2008;
Dias & Kosgamage 2008). Jayasuriya& Traniello (1985) further stated that elevations
above 450m, which is the case in two new localities
(592m and 549m), are correlated with the distribution of A. simoni. However, this ant has been recorded from
much lower elevations such as 112m in Kirikandaforest (Dias et al. 2011).
The discovery of A. simoni from semi-evergreen forests at Rambukoluwa area extends its distribution to Matale District and is the first record of this species
from the intermediate zone of the country. In addition, this study emphasizes the importance of Knuckles Mountain
Range as an area with important biodiversity. Although A. simoni had been reported from Kandy District in the early days (Emery 1893; Wilson
et al. 1956) its presence was not re-confirmed in later studies (Jayasuriya & Traniello 1985)
until the present study in Moraella forest in the
Kandy District. Findings of the
present study highlight the importance of recording the current distribution ofA. simoni within the country to re-evaluate
the conservation status of this world’s sole representative ant species of the
subfamily Aneuretinae.
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