Dragonflies of Hong Kong
Although known for its skyscrapers, Hong Kong is also home for a rich variety of dragonflies. Since the first local record was made in 1854, a total number of 128 dragonfly species, including two endemic species and more than 10 species new to science, have been recorded from Hong Kong (9 species are considered as vagrant and 6 species are considered as historical record).
Studies of dragonflies in Hong Kong started in 1850s and Euphaea decorata Hagen was the first dragonfly recorded here by Baron de Selys Longchamps in 1854 (Selys 1854).
Various studies were then carried out, and Asahina (1965) made the first comprehensive documentation of Hong Kong's dragonflies with details of 55 species provided in his document. New species were continuously added to the records of dragonflies in Hong Kong by the concerted efforts of various researchers (Asahina & Dudgeon 1987, Hämälänen 1991, Wilson 1993). Finally Wilson (1997) updated and compiled the records of local dragonflies, and provided an annotated checklist of 107 Hong Kong dragonfly species. The Dragonfly Working Group of Agriculture, Fisheries and Conservation Department (AFCD) has carried out intensive and territory-wide surveys on dragonflies since 2002 and raised the total number of dragonfly species recorded in Hong Kong from 107 to 128. The geographical information and current status of Hong Kong dragonflies, as well as their representation in protected areas in Hong Kong were also updated (Tam et al. 2011). The dragonfly species recorded now include six families of sub-order Anisoptera (dragonflies) and eight families and 1 group of incertae sedis of sub-order Zygoptera (damselflies).
All members of the order Odonata are known as dragonflies. The Odonata order is divided into three suborders including the Anisoptera (containing more or less robust dragonflies), the Zygoptera (known as damselflies) and the Anisozygoptera. The latter suborder contains just four relict species of Epiophlebia from China, Japan and the Himalayas, which have affinities with both the Anisoptera and the Zygoptera.
The majority of damselflies are much smaller and more delicately built than the Anisopteran dragonflies. However there are exceptions in the Hong Kong fauna such as Philoganga vetusta, which is a huge and robustly built damselfly of similar dimensions to a medium sized aeshnid dragonfly. Structurally, damselflies have a number of differences and are characterised by widely separated eyes, and wings narrow at base with hind wing of similar shape to the forewing and usually held closed together at rest. Lestid, Philogangid and Rhipidolestes (within the family of incertae sedis) damselflies are exceptions with most species spreading their wings open at rest. Zygopteran males have two pairs of both superior and inferior anal appendages whereas Anisopterans have just a single male inferior appendage. All female damselflies have well developed ovipositors. The larvae possess three, or occasionally two, caudal gills unlike Anisopterans which rely on internal rectal gills.
Anisoptera in Hong Kong have eyes which are not separated, except for Cordulegastridae and Gomphidae in which the eyes are separated by a space less than the eyes' own diameter. The wings are usually held horizontally or depressed when at rest and the hind wing is always broader than the forewing near the base. The male has just one inferior anal appendage. The larvae have internal tracheal gills.
In 1997, Wilson (1997) listed eight endemic dragonfly species. However, the status of the endemic species has been reviewed recently and now only two dragonfly species are regarded as endemic to Hong Kong. They are Fukienogomphus choifongae and Leptogomphus hongkongensis.
The local status of the dragonflies of Hong Kong was reviewed in 2015, and the dragonflies are classified into 6 classes, i.e. rare, uncommon, common, abundant, vagrant and historical. As of September 2019, there are 6 rare and 22 uncommon species in Hong Kong. Habitats of these rare and uncommon dragonfly species are very diverse, including sandy and rocky streams, freshwater ponds, seasonal marshes, reservoirs, freshwater and brackish water marshes and waterfalls.
Apart from endemic and rare species, some other dragonfly species of Hong Kong are considered to be of special interest. These are Nannophya pygmaea and Agriocnemis pygmaea, which are the smallest dragonfly and the smallest damselfly in the world respectively.
Current protection status of the rare and uncommon dragonfly species of Hong Kong listed by Wilson et al. (2004) has been reviewed and the dragonflies are found to be well represented, either exclusively or partially, inside existing protected areas (Country Parks, Special Areas, Sites of Special Scientific Interest (SSSI) and Restricted Areas). Excluding those historical and vagrant records, all rare and uncommon species were well represented within the protected areas. Populations of most of the locally rare and uncommon dragonflies are thus considered to be safeguarded under the existing protection measures against development threats.
Various public education programmes have been carried out to increase the awareness of dragonfly conservation in Hong Kong. Latest edition of the bilingual Field Guide - The Dragonflies of Hong Kong was published in 2011 to help members of the public familiarize with the diversity of Hong Kong dragonflies – and to help them understand more about the importance of dragonflies to the wetland ecosystem. In addition, a website (Hong Kong Live Eco-map) introducing the dragonflies of Hong Kong was established and launched in 2005.
Lau Shui Heung Reservoir
Lau Shui Heung Reservoir is located in Pat Sin Leng Country Park, which lies in the northeastern New Territories. It is a small reservoir, lushly surrounded by tall trees. Take a walk there and you will enter a world of serenity, leaving behind the hustle and bustle of the city. The pleasant Lau Shui Heung Country Trail takes you to different wetlands, including waterside woodlands, rocky streams and freshwater marsh. There you can have a glimpse of the fascinating world of local dragonflies when these beautiful insects are on the wing in spring and summer. The dragonflies you may see in Lau Shui Heung Reservoir are Copera marginipes, Mnais mneme, Heliocypha perforata perforata, Prodasineura autumnalis, Pseudagrion rubriceps rubriceps, Ictinogomphus pertinax, Orthetrum chrysis, Pseudothemis zonata, Tramea virginia and Trithemis aurora.
Located in Aberdeen Country Park, Aberdeen valley is one of the largest depressions on Hong Kong Island. Its hillsides are covered with rugged rocks and thick woods. Among the dense and shady trees are numerous streams that flow into the Upper and Lower Aberdeen Reservoirs, nestled in the valley. Situated near the town, this lovely area is quickly reached from the city. Walking along the well-wooded path that starts from the entrance of the Country Park, the route runs along Aberdeen Reservoir Road and Lady Clement's Ride and then goes back to the Upper Aberdeen Reservoir. Here you will pass calm pools, small and large brooks, water that seeps from the cracks of rocks, and the waterfall pouring down from the steep peak of Mount Cameron into the Upper Aberdeen Reservoir. In these diverse stream habitats, all dragonfly species thrive - and so the valley is one of the best places in Hong Kong for dragonfly watching between spring and summer. Dragonflies you may see in Aberdeen Valley include Agriomorpha fusca, Calicnemia sinensis, Coeliccia cyanomelas, Copera marginipes, Euphaea decorata, Prodasineura autumnalis, Protosticta taipokauensis, Pseudagrion rubriceps rubriceps, Anax guttatus, Anax parthenope julius, Ictinogomphus pertinax, Orthetrum glaucum, Orthetrum pruinosum neglectum. Orthetrum triangulare triangulare, Pantala flavescens, Pseudothemis zonata, Tramea virginia, Trithemis aurora, Trithemis festiva, Zygonyx iris insignis.
Dragonfly Pond of the Lions Nature Education Centre
Located at an eco-tourism attraction in Sai Kung, the dragonfly pond at the Lions Nature Education Centre is the first Hong Kong water habitat made specifically for dragonflies. The pond has been designed to encourage the development of a diverse community of aquatic plants, with many emergent reeds, irises, sedges and lilies and a variety of submerged pondweeds. With time, as the plants mature, the pond is expected to support about a quarter of the dragonfly species found in Hong Kong. A visit to this pond will be a good start for beginner dragonfly watchers. The dragonflies you may see there are Anax guttatus, Anax parthenope julius, Neurothemis fulvia, Orthetrum chrysis, Orthetrum glaucum, Orthetrum luzonicum, Orthetrum pruinosum neglectum, Orthetrum sabina sabina, Pantala flavescens, Pseudothemis zonata, Tramea virginia, Trithemis aurora and Trithemis festiva.
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