Tetracanthagyna plagiata
Giant hawker | |
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Artist's rendition of a female Tetracanthagyna plagiata | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Odonata |
Infraorder: | Anisoptera |
Family: | Aeshnidae |
Genus: | Tetracanthagyna |
Species: | T. plagiata
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Binomial name | |
Tetracanthagyna plagiata Waterhouse, 1877
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Synonyms | |
Gynacantha plagiata Waterhouse, 1877 |
The giant hawker (Tetracanthagyna plagiata) or the gigantic riverhawker, is a species of dragonfly in the family Aeshnidae. It is found throughout Sundaland, having been recorded on Thailand, Peninsular Malaysia, Singapore, Sumatra, and Borneo. It is the type species for the genus Tetracanthagyna.
It is the heaviest of all living Odonata, and additionally are the second largest of all living Odonates by wingspan, second only to Megaloprepus caerulatus (Pseudostigmatidae). T. plagiata is additionally the largest living dragonfly, with a maximum wingspan of 163 millimeters, exceeding the wingspan of runner-up Petalura ingentissima at 162 millimeters.
Taxonomy
Tetracanthagyna plagiata was initially described by
Description
The giant hawker is a large black-bodied dragonfly with large wings. The thorax is black in color,[8] with the side of the synthorax marked with two pale yellowish bands, differentiating it from the reddish brown bands of the related Tetracanthagyna brunnea.[9] The abdomen is reddish-brown in color and cylindrical in shape, with a length of 100 millimetres (3.9 in),[10] and narrowing in size to the tip of the abdomen.[8] Tetracanthagyna plagiata has a variable distal transverse banding pattern on the forewings and hindwings, with males and some females sporting dark costal streaks.[9]: 75 Only a few specimens of T. plagiata lack the dark bands.[11] According to Leonard Tan of the blog Singapore Odonata, males lack the transverse brown patches near the wing tips that females have. Apart from differences in wing patterns, males and females of the giant hawker are very similar in appearance.[12]
The giant hawker is
Largest dragonfly
The giant hawker is the heaviest of all living Odonates, the largest living dragonfly (infraorder Anisoptera),[14][15][16] and the second largest living Odonate overall, behind the damselfly Megaloprepus caerulatus.[11][17] Tetracanthagyna plagiata has been known to reach upwards of 163 millimeters in wingspan,[14][10] with a body length of 100 millimeters.[10] This puts T. plagiata as being the largest living Anisopteran, surpassing Petalura ingentissima at 162 millimeters. There is some uncertainty regarding T. plagiata's weight, with Paulson (2019) stating that there is no weight records available for T. plagiata.[18] However most researchers are generally in agreement that females of T. plagiata are the heaviest living Odonate.[19][11][17] Corbet (1999) stated that a male specimen of Tetracanthagyna plagiata had a hindwing span of 144 millimetres (5.7 in).[13] The wingspan of T. plagiata specimens held at the Lee Kong Chian Natural History Museum (formerly the Raffles Museum of Biodiversity Research) were between 134 millimeters and 144 millimeters,[20] with another account putting T. plagiata at a wingspan of 160 millimeters,[15] putting T. plagiata additionally as the largest Anisopteran in Southeast Asia.[21]
Regarding the size of T. plagiata, studies by Dorrington (2012) have shown that the practice of aerial predation inhibits further size development of extant Anisopterans. Specimens of both the giant hawker and Petalura ingentissima were measured for their hindwing lengths for the aforementioned study. Specimens stored at the Natural History Museum, London had a hindwing length of 84-86 millimeters.[22]
Life history
Females lay their eggs within rotting logs and other soft substrates covered by moss[19] by streams through inserting their ovipositor into the rotten log. Before doing so, the female would scrape at the surface for a minute to prepare the surface while arching its abdomen. One female was spotted by the MacRitchie Reservoir displaying the aforementioned behavior. Watanabe (2003) recorded a female T. plagiata depositing its eggs into decaying wood, 150 centimeters above the water's surface.[11]
The larvae of Tetracanthagyna plagiata were previously unknown to science, unlike the larvae of related species. Studies of the related Tetracanthagyna waterhousei in Hong Kong recorded larval predation of fish and its
Orr et al., in the first ever larval description for a T. plagiata nymph, described the larva as a large elongate aeshnid larva.[17]: 155 The outline of the larva was primarily angular, and it had a "distinctive, pronounced" sculpturing on its head.[17]: 155 The banded coloration on its legs was the only deviation from its dark appearance. The larva's legs were short and robust, which were adapted for performing grasping.[17]: 155 The larval mask (a hinged lower mandible also known as a "hinged labium") had a robust prementum with distal expansion, and the short, thin labial palps had serrated inner margins along its terminal hook.[17]: 155, 157 Male exuviae were 57.5 millimetres (2.26 in) long, and those of the female were 62 millimetres (2.4 in) long.[17]: 160 Compared to the larvae of related species Tetracanthagyna waterhousei and Tetracanthagyna degorsi, T. plagiata's larvae had a more angular head.[17]: 159
Adult dragonflies forage during the dawn and dusk and are
Distribution
The giant hawker is found throughout the Oriental region of Southeast Asia, throughout the biogeographical region of Sundaland.[9]: 75 It is found in the countries of Thailand,[1] Malaysia, Singapore, Brunei, and Indonesia.[1][23]
Frank Fortescue Laidlaw (1901) described T. plagiata as being recorded on the islands of Sumatra and Borneo.[5]: 79 René Martin (1909) described T. plagiata as being found in Borneo, Sumatra, and Malacca. M. A. Lieftinck (1954) stated that T. plagiata was also found in Singapore,[24][11] where it is the only member of the genus Tetracanthagyna on the island.[17]: 154 It has also been recorded in the state of Johor on Peninsular Malaysia.[7]
Habitat
Male larvae were found in slow-moving streams within
Threats and conservation
Tetracanthagyna plagiata was assessed in 2010 by the
In a survey of Odonates conducted at nature reserves within Singapore, D.H. Murphy listed the species as "rare" within the Nee Soon Swamp Forest of Singapore.[25] Y. Norma-Rashid corroborates upon this account, listing the species as "rare" on a checklist of Singaporean dragonflies.[20] Murphy additionally stated that his report was an "old record". He proceeded to describe the giant hawker as "totally confined" within Nee Soon Swamp Forest.[25] Leong et al. subsequently reported that the giant hawker has been seen multiple times outside of the Nee Soon Swamp Forest, being found within the broader context of the Central Catchment Nature Reserve within Singapore.[11] In a 2016 revision of Murphy's previous work and an update of the national conservation status for various Odonata, T. plagiata was listed as "Restricted & Uncommon", receiving the designation of "Vulnerable".[26][27]
See also
- Meganeura monyi, prehistoric griffinflies
- Megaloprepus caerulatus, the largest Odonate by wingspan at 191 millimeters
- Petalura ingentissima, the second largest Anisopteran at a wingspan of 162 millimeters, longest in terms of body length at 125 millimeters
- Mecistogaster lucretia, the longest Odonate by body length at 150 millimeters
- Chlorogomphus papilio, the Odonate with the largest wing area with a maximum breadth of 35 millimeters
References
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- ^ "Tetracanthagyna plagiata". www.mindat.org. Archived from the original on 16 November 2021. Retrieved 16 November 2021.
- ^ ISBN 978-3-11-014934-0. Archivedfrom the original on 18 April 2022. Retrieved 16 November 2021.
- ^ a b c "Considerations on the Genus Tetracanthagyna". Transactions of the Royal Entomological Society of London. Royal Entomological Society of London. 1899. pp. 439–444. Archived from the original on 18 April 2022. Retrieved 3 January 2022.
- ^ a b Laidlaw, Frank Fortescue (1902). "Dragonflies of the "Skeat Expedition."". Journal of Zoology: Proceedings of the Zoological Society of London. London: Zoological Society of London. Archived from the original on 18 April 2022. Retrieved 3 January 2022.
- ^ a b Fraser, F.C. (1936). The Fauna of British India, Including Ceylon and Burma, Odonata Volume III (PDF). Taylor and Francis. pp. 115–119. Archived (PDF) from the original on 2022-01-08. Retrieved 2022-04-18.
- ^ a b "Tetracanthagyna plagiata". Malaysia Biodiversity Information System (MyBIS). Archived from the original on 16 November 2021. Retrieved 16 November 2021.
- ^ a b Tan, Leonard (26 July 2014). "Tetracanthagyna plagiata (Waterhouse, 1877)". PICTURE OF SINGAPORE ODONATA. Archived from the original on 16 November 2021. Retrieved 10 January 2022.
- ^ ISBN 983-812-103-7. Archivedfrom the original on 18 April 2022. Retrieved 16 November 2021.
- ^ from the original on 18 April 2022. Retrieved 16 November 2021.
- ^ a b c d e f g h Leong, T.M.; Tay, S.L. (2009). "ENCOUNTERS WITH TETRACANTHAGYNA PLAGIATA (WATERHOUSE) IN SINGAPORE, WITH AN OBSERVATION OF OVIPOSITION (ODONATA: ANISOPTERA: AESHNIDAE)" (PDF). Nature in Singapore. 2. National University of Singapore: 115–119. Archived (PDF) from the original on 16 November 2021. Retrieved 16 November 2021.
- ^ "Tetracanthagyna plagiata (Waterhouse, 1877) – ♂". Picture of Singapore Odonata. 20 March 2015. Archived from the original on 16 November 2021. Retrieved 16 November 2021.
- ^ ISBN 978-90-04-47438-3. Archivedfrom the original on 18 April 2022. Retrieved 5 January 2022.
- ^ a b "World's 'largest' dragonfly caught at varsity". The Star. 28 January 2003. Archived from the original on 18 November 2021. Retrieved 18 November 2021.
- ^ a b c Fah, Cheong Loong; Bun, Tang Hung; Jiang, Robin Ngiam Wen (January 2010). Ode to Odonata (PDF). Nature Watch. pp. 8–16. Archived (PDF) from the original on 16 November 2021. Retrieved 16 November 2021.
- ^ "A Celebration Of Dragonflies - The Malta Independent". The Malta Independent. Archived from the original on 2021-11-16. Retrieved 16 November 2021.
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- ^ a b Glime, Janice M. (2017). "CHAPTER 12-3 TERRESTRIAL INSECTS: HEMIMETABOLA – ODONATA". Bryophyte Ecology Volume 2: Bryological Interaction. 12 (Chapter 12 - Terrestrial Insects). Archived from the original on 7 November 2021. Retrieved 16 November 2021.
- ^ ISBN 978-981-08-1745-9. Archivedfrom the original on 2022-04-18. Retrieved 2021-11-16.
- ^ "Factsheet : Bukit Timah Nature Reserve" (PDF). National Parks Board. National Archives of Singapore. Archived (PDF) from the original on 16 November 2021. Retrieved 16 November 2021.
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- ^ "List of Insects Species that are Native in Indonesia". ASEAN Centre for Biodiversity. Archived from the original on 18 April 2022. Retrieved 16 November 2021.
- ^ "Dragonfly - List of damselfly and dragonfly species present in Singapore". National Parks Board. Ministry of National Development. Archived from the original on 16 November 2021. Retrieved 16 November 2021.
- ^ a b Murphy, D.H. (1997). "Odonata Biodiversity in the Nature Reserves of Singapore" (PDF). Proceedings of the Nature Reserves Survey Seminar. Gardens' Bulletin Singapore. 49. Department of Biological Sciences National University of Singapore: 333–352. Archived (PDF) from the original on 27 October 2021. Retrieved 16 November 2021.
- ^ Ngiam, Robin Wen Jiang; Cheong, Loong Fah (8 September 2016). "The dragonflies of Singapore: An updated checklist and revision of the national conservation statuses" (PDF). Nature in Singapore. 9. National University of Singapore: 149–163. Archived (PDF) from the original on 16 November 2021. Retrieved 16 November 2021.
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