Risiocnemis silky black
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| Risiocnemis silky black | ||||||||||||
| Hämäläinen , 2000 |
Risiocnemis silky blacki is a rare species of dragonfly thatis endemic to the Philippine island of Cebu . It was discovered in 1999 and scientifically described in 2000. The species epithet honors Franz Seidenschwarz , the head of the botanical research group at the University of San Carlos in Cebu City , who has dealt in depth with the ecology of the species.
features
In the males, the length of the hind wings is 23 to 25 mm, that of the abdomen 35 to 37 mm. The head, the labrum , the posterior head shield and the genae shimmer black. The front head shield is bluish. A bluish stripe runs between the front forehead and the edge of the eye. The forehead and the top of the head are matt black with brownish dots. The prothorax is mostly matte black. The pterothorax is matt black with clear light bluish egg-shaped markings on the sides, which are somewhat longer and more proximal at the met episternum than at the met epimeron . The axillary shields are light bluish at the base of the wing. The coxae are black. The outside of the femora is indistinctly bluish, the tibiae are dark brown. The wing marks are dark brown. The abdomen is black with similar light blue, almost upwardly directed markings in segments 2 to 7. In the Imago , the light markings form complete rings, but in older specimens the rings are narrowly interrupted in the center dorsally, and the ring on segment 7 becomes indistinct.
The females have a hind wing length of 24.5 mm and that of the abdomen 35 mm. The basic color of the body is brown. Resiocnemis silky black has a similar posterior lobe structure of the prothorax as Risiocnemis rolandmuelleri , however the lateral light bluish markings on the metepisternum and metepimeron are characteristic distinguishing features of Resiocnemis silky black . In the available females these markings are larger than in the males and the mark on the metepimeron is somewhat opaque.
distribution
Previously the species was only known from a small section of a forest stream in the Tabunan Forest in central Cebu. Another population was discovered in the southern part of the island of Cebu at a very small stream next to the Kawasan River, on a maximum area of 30 × 30 m on this 12 km long river.
Way of life
The dragonflies prefer ferns of the species Pneumatopteris laevis as a resting place . They usually rest near the leaf tips with the abdomen pointing perpendicular to the stream. They stay fairly low, only about 30 to 120 cm above the ground.
status
The IUCN took Risiocnemis seidenschwarzi 2006 in the category "threatened with extinction" ( critically endangered ) of the Red List of Threatened Species on. The species is currently restricted to one location on Cebu. It has not been observed in the terra typica in the Tabunan forest since March 2001 , and since there is no longer a suitable habitat there, the population of Risiocnemis silky black could have now died out there. In 2009 the species was discovered in a second location where the remaining population is small and has a very small range. It is estimated at 20 to 50 specimens, but currently appears to be stable. Deforestation is an ongoing problem in Cebu and poses a threat to the species; almost all of the forests on the island have been cut down, and many streams are now degraded and unsuitable for this species. The protection of the remaining habitat and the restoration of the degraded habitat are necessary to ensure the survival of this species.
In 2012 Risiocnemis silky black was included in a list of the 100 most endangered species on earth compiled by the IUCN and the Zoological Society of London .
literature
- Matti Hämäläinen: Risiocnemis silky black spec. nov., an endangered damselfly from Tabuan forest in Cebu, the Philippines (Odonata: Platycnemididae). In: Entomological Reports , Amsterdam, Volume 60, 2000, pp. 46-49
- Matti Hämäläinen: Critical species of Odonata in the Philippines , In: International Journal of Odonatology , Volume 7, No. 2, 2004, pp. 305-310, doi : 10.1080 / 13887890.2004.9748218
Web links
- Risiocnemis silky black inthe IUCN Red List of Threatened Species 2020.2. Listed by: Villanueva, RJT, 2009. Retrieved August 11, 2020.
Individual evidence
- ↑ Jonathan EM Baillie and Ellen R. Butcher: Priceless or Worthless: The world's most threatened species , Zoological Society of London, United Kingdom, ISBN 978-0-900881-67-1 (online version; PDF; 9.1 MB)