Panay monitor lizard
| Panay monitor lizard | ||||||||||||
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Drawing of the Panay monitor |
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| Scientific name | ||||||||||||
| Varanus mabitang | ||||||||||||
| Gaulke & Curio , 2001 |
The Panay Monitor ( Varanus mabitang ), also called by the local name Mabitang known, a large lizard from the kind of lizards ( Varanus ). The species is endemic to the island of Panay, which belongs to the Philippines, and was not scientifically described until 2001; Accordingly, the species is currently sparsely researched. This black monitor lizard feeds differently from most other members of the genus on fruits. The species is considered endangered, the IUCN Red List classifies the Panay monitor as endangered (threatened). Inventory estimates are not available.
features
The female holotype had a head-trunk length of 52.7 centimeters and a tail length of 74.1 centimeters, a total length of 126.8 centimeters, although the tip of the tail and thus a few centimeters were missing. He weighed 1,850 grams. In measurements of 25 specimens, the head-torso length averaged 54.2 centimeters, the tail length 82 centimeters, which results in an average total length of 136 centimeters. The largest measured specimen was 175 centimeters long. The weight of the specimens varied between one and eight kilograms, on average 3.6 kilograms. According to local residents, the Panay monitor can grow very large, and lengths of more than two meters have also been mentioned.
The extremely dark monitor lizard has a black back and a dark gray to black color on the throat, neck, tail and extremities. Parts of the neck, back, and extremities show tiny, yellow scales. The snout is slightly arched, the rest of the head is very elongated. The ventral scales of the Panay monitor lizard are strongly keeled. Characteristic features of the species are bulges in the temporal region and long, strongly curved claws for climbing. The eyes are reddish brown, the tongue is pink. While the scales of the head are enlarged, the remaining scales of the Panay monitor lizard are very small, so the distance from the throat fold to the base of the hind legs includes 124 scales. The upper scales of the tail, which is triangular in cross section, have clearly delimited, double and longitudinal keels. Young animals show the same dark coloring as older specimens.
Occurrence
So far the Panay monitor lizard is only known from the northwestern Panay peninsula and the western mountains of Panay . It lives mainly in primary or (albeit rarely) secondary rainforests in flat and hilly regions at altitudes of up to 1000 meters above sea level . The species seems to be most common at altitudes between 200 and 500 meters above sea level.
According to surveys of locals, a “large, black monitor lizard” could also exist on Mindoro , thus perhaps also the Panay monitor lizard. Possible locations are the Siburan Forest on West Mindoro and a small forest on East Mindoro. In contrast to Panay, where it is called "Mabitang", there is no local name there. However, this could be a mistake, because in this area, Varanus salvator nuchalis, a subspecies of the water monitor and possibly a black morph of it, lives . The occurrence can only be considered certain if a specimen is caught there.
Way of life
The Panay monitor is strictly arboreal (tree-dwelling), it only occasionally comes to the ground, mostly to eat fallen fruit or to sunbathe. It can climb very well and also climbs wing fruit plants with tall trunks and hard bark. Short distances are covered by jumping from tree to tree. He uses tree holes as a hiding place and also sleeps on branches. According to reports from hunters, it is more active in sunny weather, nothing is known about changing seasonal and daily activity. Studies have shown that individual individuals do not use the same trees at the same time, but change them often: A single monitor lizard used 70 different trees within two years.
The frugivorous (fruit-eating) Panay monitor probably absorbs the smell of ripe fruit with its Jacobsonian organ and also lives on these fruit trees. The monitor lizard eats the fruits of at least 20 different trees, preferably screw trees , palms of the Arecaceae family and fig trees of the Moraceae family. Like the Grays monitor lizard ( V. olivaceus ), the Panay monitor lizard also has a well-developed appendix to adapt to the vegetarian diet, the teeth are blunt. He is therefore highly specialized. Occasionally it also eats various arthropods .
Little is known about the reproduction of the Panay monitor lizard; local hunters counted six to twelve eggs per female. The female holotype caught in May and thus in the rainy season contained ovarian follicles five to seven millimeters in size. Apparently, the tree hollows are not only used as a resting place: the shell remains of the hatched clutch of a large reptile were discovered in a tree hollow. The probability that this clutch came from a Panay monitor lizard is very high.
When a Panay dragon is startled on the ground, it climbs the next tree. If it is pursued up the tree, it does not try to jump from the tree like the bandage monitor , but climbs as high as possible. Typically, when cornered there, he threatens with a distended throat, whipping tail movements and hissing, but he rarely attacks. If the animals were restrained with the hands, they did not try to defend themselves and did not show any threatening gestures typical of the war. Lizards caught by humans had their heads, tails and extremities drooping, which also confirmed the statements of a hunter that they often play dead in defense.
So far, the ticks Amblyomma helvolum and Aponomma fimbriatum have been identified as ectoparasites on the Panay dragon . On average, a monitor lizard had 18.4 ticks each, but the infestation ranged from zero to 62 ticks. Most ticks were found on the roots of the legs, in the throat region and around the cloaca. The droppings from the Panay monitor lizard contained roundworms (Nematoda).
Panay monitors observed in the wild did not have any scratches in the middle of the body, which, for example, are often a result of the commentary fights in bandage monitors . So there are probably no such fights with Panay dragons.
Systematics
On the basis of an examination of the hemiclitoris of the female holotype, Varanus mabitang was placed together with Varanus olivaceus in the subgenus Philippinosaurus . The ossified parts of the hemipenes and the hemiclitores, the hemibacula of the two species, are very similar. Such structures usually have no apparent purpose and are therefore little affected by changes in the course of evolution. Therefore, researchers use them to determine relationships. Philippinosaurus probably split off from other monitor lizards early on.
Panay dragons and humans
The Panay monitor lizard was discovered on Panay in 2000 as part of a project to protect hornbills , the first description was in 2001. Immediately after the discovery, the Philippine Endemic Species Conservation Project (PESCP) asked itself how rare the monitor lizard is. The fact that this large species had remained undiscovered for a long time on a densely populated island, which herpetologists have often visited, suggested that the species is very rare. The Frankfurt Zoological Society (ZGF) and the PESCP are now investing a great deal of energy in researching this species, as protective measures can only be carried out if data on distribution, population, biology and habitat requirements are available. One project investigates the distribution of Varanus mabitang on Panay and the neighboring islands, a second project aims to research the biology of this lizard in the known distribution area. The projects are supported by the BIOPAT association , the FZS and the German Society for Herpetology and Terrarium Science (DGHT).
The number of sightings, scratches and excrement finds shows that Panay dragons are more common on northwest and west Panay than initially assumed. Nevertheless, there is probably a threat as the relatively small area in the rainforest is increasingly being destroyed. The PESCP has meanwhile been able to achieve the designation of the rainforest of northwestern Panay as a nature reserve; the protection provisions are enforced by rangers, but also by the police and the military. However, it is questionable whether the small area can preserve the Panay monitor lizard, and because of the great distance to the occurrence in West Panay, only a limited exchange of population is possible. The protection of the forests in West Panay could probably ensure the preservation of the species much better than the current individual conservation area. In most areas, the number of monitor lizards has now declined critically, and the first person to describe it believes that the Panay monitor lizard could become extinct within a few years if comprehensive protective measures are not introduced soon.
swell
literature
- Maren Gaulke: Varanus mabitang . In: Eric Pianka & Dennis King (Eds.): Varanoid lizards of the world . Indiana University Press, published 2004, ISBN 0-253-34366-6 , pp. 208-211.
- M. Gaulke et al .: On the distribution and biology of Varanus mabitang . 2005, Silliman Journal Vol. 46 No. 1, pp. 89-117.
- M. Gaulke: Field studies on the Mabitang (Varanus mabitang), a severely threatened large monitor species from the Philippines island of Panay . 2005, Elaphe 13 (1), pp. 51-56.
Individual evidence
- ↑ Varanus mabitang in the Red List of Threatened Species of the IUCN 2008. Posted by: Gaulke, M., Diesmos, A., Demegillo, A. & Gonzalez, JC, 2007. Retrieved on December 19 of 2010.
- ↑ a b c d e Maren Gaulke: Overview on the Present Knowledge on Varanus mabitang Gaulke and Curio, 2001, Including New Morphological and Meristic Data . Biawak, 4 (2), 2010; Pp. 50-58
- ↑ M. Gaulke et al. (2005): On the distribution and biology of Varanus mabitang . Silliman Journal Vol. 46 No. 1: 89-117
- ^ A b M. Gaulke & A. Demegillo (2001): Well hidden in the trees: The Panay-Waran . Communications from the Frankfurt Zoological Society 4: 4–6
- ↑ U. Struck, A. Altenbach, M. Gaulke & F. Glaw (2002): Tracing the diet of the monitor lizard Varanus mabitang by stable isotope analyzes ( 15 N, 13 C) . Science 89: 470-473
- ↑ M. Gaulke, E. Curio, A. Demegillo & N. Paulino (2002): Varanus mabitang, a rare monitor lizard from Panay Island and a new conservation target . Silliman Journal 43: 24-41
- ↑ T. Ziegler, M. Gaulke, W. Böhme: Genital Morphology and Systematics of Varanus mabitang Gaulke & Curio, 2001. In: Current Herpetology. 24 (1) 2005, pp. 13-17.
