Odonata (Insecta) at a wadi Pool near Nizwa, northern Oman

 

Elaine M. Cowan 1 & Peter J. Cowan 2

 

1 School of Education, University of Aberdeen, Scotland, UK

2 Department of Biological Sciences and Chemistry, University of Nizwa, Sultanate of Oman

1 desertlarksgirl@hotmail.com, 2desertmammal@yahoo.com (corresponding author)

 

doi: http://dx.doi.org/10.11609/JoTT.o4207.7538-46 | ZooBank: urn:lsid:zoobank.org:pub:D83BD6B0-0559-4A37-87F2-08F97BBAE89F

 

Editor: Jean-Pierre Boudot, French National Centre for Scientific Research, Paris, France. Date of publication: 26 July 2015 (online & print)

 

Manuscript details: Ms # o4207 | Received 05 January 2015 | Final received 25 June 2015 | Finally accepted 30 June 2015

 

Citation: Cowan, E.M. & P.J. Cowan (2015). Odonata (Insecta) at a wadi Pool near Nizwa, northern Oman. Journal of Threatened Taxa 7(9): 7538–7546; http://dx.doi.org/10.11609/JoTT.o4207.7538-46

 

Copyright: © Cowan & Cowan 2015. Creative Commons Attribution 4.0 International 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: None.

 

Competing interests: The authors declare no competing interests.

 

Acknowledgements: The JoTT review process significantly improved the manuscript.

 

 

 

Abstract: Fourteen damselfly and dragonfly species were recorded in 68 visits to a wadi pool in northern Oman, March 2012 to June 2014. All identifications were based on photographs. Apparently the pool has a core community of eight resident species. Paragomphus sinaiticus, globally Near Threatened, was regularly recorded.

Keywords: Anisoptera, Arabia, phenology, reproduction, species inventory, Zygoptera.

 

 

 

 

 

The damselflies and dragonflies, Odonata, of Oman are known largely through the collection of specimens and photographic records. In the latest checklist of the odonate fauna of Oman, Schneider & Dumont (1997) recorded 40 species, collating information from 1912 onwards. Two species have been added recently. Ischnura fountaineae Morton, 1905 was photographed in northern Oman (Reimer et al. 2009) and Tholymis tillarga (Fabricius, 1798) was reported from Dhofar (Ball 2014), over 1000km to the south. Oman is largely a desert country with a mainly arid climate. Rainfall in the north is in the winter though monsoon-induced summer rainfall sometimes occurs (e.g., Fisher et al. 1999).

The present paper describes odonates recorded over an extended period at a wadi (valley) pool in the southern foothills of the Jebel Akhdar mountain range, near Nizwa, northern Oman. In all, 68 visits of several hours each were made to the pool during 23 months between March 2012 and June 2014. Cowan & Cowan (2013) described the wadi pool and odonate species seen there from March 2012 to June 2013. Here we present monthly occurrence of odonates, including mating and egg laying, over the full period for the 14 species observed including four first seen after June 2013.

 

Study Area

The pool (2304.53’N & 57021.57’E, 680m, Fig. 1, Image 1) is in the southern foothills of the Jebel Akhdar range, the highest section of the Hajar mountains of northern Oman. It is a few kilometres from the Al Hoota cave, a tourist attraction, and about 22km northwest of the rapidly developing city of Nizwa. The pool is fed by seepage from a mountain spring and varies in size dramatically over time due to rainfall, or the lack of it, in the wadi’s catchment. The southern and eastern sides of this apparently permanent pool are a popular picnic site especially at weekends.

 

 

 

 

 

Methods

All our identifications at the pool (Table 1) were based on digital photos, allowing for later deliberation and confirmation. All photos were taken by E.M.C. using a handheld Sony Cybershot compact camera. The data includes the monthly occurrence of odonate species, presenting the number of visits in a month in which we photographed the species. No visit was made in June, July, November, December 2012 or July 2013. The occurrence of mating and egg laying by month except for the ‘no-visit’ months are also presented. Every datum is supported by a ‘voucher photo’ in E.M.C.’s personal collection. Identification was facilitated in many cases by reference to Dijkstra & Lewington (2006), the field guide to the odonates of Europe and western Turkey, Cyprus and northwestern Africa. Also useful were well-illustrated papers on the odonate fauna of the adjoining United Arab Emirates (Giles 1998; Feulner et al. 2007; Reimer et al. 2009), the Asia/Africa Dragonfly website (www.allodonata.com), Samways (2008), Subramanian (2009), and Smallshire & Swash (2014).

 

 

 

Results

Table 1 lists the 14 odonate species (Images 2 to 31) we recorded at the pool. Images 2 to 30 were taken at the pool during our study period and identification notes are given in their captions. Table 2 presents monthly occurrence whilst Table 3 notes the months when mating and laying were observed and photographed. A variety of different exuviae were observed around the pool. Large Anax-type exuviae were most frequently recorded but usually several other types of exuviae were present sometimes in large numbers on the poolside rock faces, boulders, grass and other vegetation in and around the pool.

Trithemis kirbyi was the only species recorded in all 23 months in which observations were made. On occasion this species was very numerous (in their hundreds) and generally it was the most numerous species at the pool. On very hot afternoons, T. kirbyi crowded into the shade in large groups. It was the sole species we located in August and September 2012 when the pool was deeply flooded after summer rains and water was fast flowing over the head dam wall.

 

 

 

 

 

Both zygopteran species were recorded mating and ovipositing. A popular mating site for Ischnura evansi was in the lower branches of a sidr tree Ziziphus spina- christi (L.) Desf. that overhangs the pool. Photographic data showed that one pair of I. evansi was in copula on the same branch for more than two hours (Image 3). Female Ischnura damselflies seen laying (they oviposit without a male in attendance and are notoriously difficult to identify to species) were presumed to be Ischnura evansi (Image 4) as no other Ischnura species was recorded at the pool (see Table 3). Pseudagrion decorum also mated regularly (Image 6) but chose a wider range of sites—the branches of the sidr, but also twigs or rocks in the pool. Oviposition (Image 7) took place in the way described by Feulner (2001) with the pair mating and then descending in tandem on a stem or into a weed patch with the female below the water surface. Oviposition by this Pseudagrion species was usually observed as lasting for 1–2 minutes rather than up to five minutes submerged as noted by Feulner (2001).

 

 

 

 

Reproductive behaviour was recorded for eight of the anisopteran species. Both Orthetrum chrysostigma and O. sabina were recorded in mating wheels (Images 15, 17) and then ovipositing on many occasions. Anax imperator was not seen mating but females were observed on many occasions ovipositing (Image 8, Table 3). Often two or three females were recorded but, on one occasion, seven females were seen ovipositing simultaneously in patches of floating weed or other vegetation in the pool. Sometimes, when several males were patrolling the pool, one pursued a female but she flew along pulling down her abdomen into a laying pose, indicating rejection of mating (Corbet 1999: 471–472). Crocothemis erythraea was observed mating on many occasions in winter/spring 2014. As a pair began to copulate in flight over the pool, there was a characteristic wing-clattering sound. They remained in copula for much less than a minute flying over the pool, sometimes settling momentarily on a stone, twig or the bank (Image 20). They quickly break apart with the male guarding the female during oviposition against other males which aggressively attempted to intrude.

 

 

 

Discussion

We recorded 14 odonate species, all included in the checklist of Oman’s Odonata by Schneider & Dumont (1997). All were globally assessed as Least Concern (IUCN 2013) except for Paragomphus sinaiticus which is globally Near Threatened (Boudot et al. 2013a).

Our phenological and reproductive behaviour data suggest that there is a core odonate community at the pool consisting of eight permanently resident species, each present on over 70% of our visits. This comprises two coenagrionid species (Ischnura evansi, Pseudagrion decorum) and Anax imperator, Orthetrum chrysostigma, O. sabina, Crocothemis erythraea, Trithemis annulata and T. kirbyi. Other species were recorded on less than 50% of visits and could represent nomadic (wanderer or migrant) individuals, although opportunistic egg-laying may occasionally occur. Paragomphus sinaiticus was recorded at the pool on 41% of visits and Trithemis arteriosa 37% of visits, though we did not record reproductive behaviour for either of these two species. Diplacodes lefebvrii was present on 23% of the visits and one pair was observed mating and laying in the pool in November 2013. Diplacodes lefebvrii’s first appearance was after a late summer storm as was that of Pantala flavescens, an obligate strong migrant (Boudot et al. 2013b). Two species, Paragomphus genei and Anax parthenope, were rare visitors to the pool.

 

References

 

Ball, L. (2014). An investigation of odonate communities within Wadi Sayq, Dhofar province, Oman (Insecta: Odonata). Checklist 10: 857–863; http://dx.doi.org/10.15560/10.4.857

Boudot, J.P., V. Clausnitzer, K.D.B. Dijkstra, F. Suhling, B. Samraoui & W. Schneider (2013a). Paragomphus sinaiticus. In: The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 4 May 2015.

Boudot, J.P., V. Clausnitzer, B. Samraoui, F. Suhling, K.D.B. Dijkstra & W. Schneider (2013b). Pantala flavescens. In: The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 4 May 2015.

Corbet P.S. (1999). Dragonflies: Behaviour and Ecology of Odonata. Harley Books, Colchester, UK, 829pp.

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Dijkstra, K.D.B. & R. Lewington (2006). Field Guide to the Dragonflies of Britain and Europe. British Wildlife Publishing, Milton on Stour, UK, 320pp.

Feulner, G.R. (2001).The damselfly Pseudagrion decorum breeding in the U.A.E. Tribulus 11(1): 24.

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IUCN (2013). The IUCN Red List of Threatened Species. Version 2014.3 <www.iucnredlist.org>. Downloaded on 4 May 2015.

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