Beni anaconda

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Beni anaconda
Beni anaconda (Eunectes beniensis) on the banks of the Río Beni, Bolivia

Beni anaconda ( Eunectes beniensis ) on the banks of the Río Beni , Bolivia

Systematics
Subordination : Snakes (serpentes)
Superfamily : Boa-like (Booidea)
Family : Boas (Boidae)
Subfamily : Boa snakes (Boinae)
Genre : Anacondas ( Eunectes )
Type : Beni anaconda
Scientific name
Eunectes beniensis
Dirksen , 2002

The Beni anaconda ( Eunectes beniensis ) is a species of snake from the family of boas (Boidae), where it is in the subfamily of the constrictor snakes found (Boinae). This anaconda , which is over three meters long , was only described in 2002. So far it has been found in tropical South America in the Bolivian departments of Beni and Pando . Nothing is known about the biology of this snake.

description

Physique and length

The species is very strongly built, the body is approximately round in cross section. The head is relatively small and only slightly separated from the neck. The eyes and nostrils are located high on the head in adaptation to the aquatic way of life. So far, apparently only 6 individuals could be measured. The largest male had a total length of 217.5 cm and the only female a length of 320.0 cm. Dirksen (2002) suspects that the species can reach at least overall lengths of 3.5 to 4 m and that, like the other anaconda species, it shows a clear sexual dimorphism in terms of body size and prominence of the anal spurs . The tail length can amount to at least 15.6% of the total length, at least in males.

Scaling

The species has slightly more scales on the head than the yellow anaconda and De Schauensees anaconda . The snout shield ( rostral ) is twice as wide as it is high. Each nostril of nose 3 shields ( nasals surrounded). The nasal shield towards the middle of the head touches the other. To the middle of the top of the head, the middle nasal shields are joined by a large pair of frontonasalia . Behind it follows a forehead shield ( prefrontal ), variable in shape and size, and a forehead shield ( frontal ). The rest of the top of the head shows large signs, which are quite irregular in number and shape. On the head side, from the nose to the eyes, there is a large, irregular, pentagonal rein shield ( Loreale ). The eyes themselves are framed by a large over-eye shield ( supraoculars ), a large fore-eye shield (pre- oculars ), 2 small under-eye shields ( subocularia ) and 2 to 3 rear-eye shields ( postocularia ). The 14 to 15 shields of the upper lip ( supralabials ) are square and about the same size. In contrast, the 17 to 19 lower lip shields ( infralabialia ) in the snout area are higher than they are wide and become smaller and smaller towards the head end. The number of abdominal shields ( ventralia ) varies between 219 and 230, the number of dorsal rows of scales in the middle of the body between 48 and 51. From the cloaca to the tip of the tail there are 54 to 59 tail underside shields ( subcaudalia ).

coloring

The upper side of the body of the Beni anaconda is brown to olive-brown, the underside is light brown in color. The species has five black head stripes. One runs from the muzzle over the middle of the top of the head to the nape of the neck and fuses with the black bars of the neck. Two more stripes each originate behind both eyes and run parallel and directed slightly back and down towards the head end. Compared to other anacondas, there are only about 98 black transverse bars on the upper side of the body to the tip of the tail, which are usually arranged regularly at a distance of about three rows of scales one behind the other. The number of flank spots is also the least pronounced in this species. The black flank spots, however, are characteristically large and round or form rings with a primary color in the center. Facultatively smaller, irregularly angular black spots lie towards the abdomen. The underside of the abdomen and the tail often show longitudinal rows of black dots.

distribution and habitat

The exact extent of the distribution area is still unexplored. So far, the species has been detected in the Bolivian Beni Department between Trinidad and Rurrenabaque and south-east from Trinidad to Ascención de Guarayos . This area includes unforested, seasonally flooded grasslands with isolated, year-round small bodies of water. Another occurrence is known further north of the northern tip of Bolivia in the Pando department , in close proximity to Brazil at the confluence of the Río Abuná and the Rio Guaporé . Details of the preferred habitat are not yet available. Even if the Beni anaconda their habitat with the sympatric occurring Great Anaconda shares, is still unknown.

Way of life

The behavior as well as the food spectrum of this snake is unexplored. So far it is only known that in the event of danger, she can wrap her head in front body loops and form a protective ball all around with the rest of the body, as is also known from the other anacondas. There is also no information on the reproduction of the Beni anaconda. Dirksen (2002) suspects, at least taking into account the climate data, that the species mates between September and October in Bolivia and that it is born about seven months later in April to May.

Systematics

The genus name Eunectes was coined by Wagler in 1830, who separated the anacondas from the genus Boa . Eunectes is Greek and means "good swimmer". The Beni anaconda ( Eunectes beniensis ) was first described by Lutz Dirksen in 2002 using animals from the Bolivian departments of Beni and Pando. The species name " beniensis " was chosen according to the main occurrence known so far. E. beniensis is closely related to the other two smaller anacondas: the yellow anaconda (E. notaeus) and De Schauensees anaconda (E. deschauenseei), but overall differs more from the other two species than they do from each other. Among the anacondas, E. beniensis , E. deschauenseei and E. notaeus represent a separate phylogenetic line compared to the large anaconda ( E. murinus ).

swell

literature

  • L. Dirksen: Anacondas: monographic revision of the genus Eunectes Wagler, 1830 (Serpentes, Boidae) . Natur und Tier Verlag, Münster 2002, ISBN 3-931587-43-6 (also dissertation University of Bonn 2001)

supporting documents

  1. ↑ a b c d e f 6. Synopsis of the genus Eunectes, 6.4.4 Eunectes beniensis sp. nov., 6.4.4.1 Diagnose , Dirksen 2002, p. 169.
  2. ↑ a b 6. Synopsis of the genus Eunectes, 6.4.4 Eunectes beniensis sp. nov., 6.4.4.4 Morphometry , Dirksen 2002, p. 171.
  3. ↑ 6. Synopsis of the genus Eunectes, 6.4.4 Eunectes beniensis sp. nov., 6.4.4.7 Gender dimorphism , Dirksen 2002, p. 172.
  4. ↑ 6. Synopsis of the genus Eunectes, 6.4.4 Eunectes beniensis sp. nov., 6.4.4.5 Pholidose , Dirksen 2002, pp. 172-173.
  5. ↑ a b 6. Synopsis of the genus Eunectes, 6.4.4 Eunectes beniensis sp. nov., 6.4.4.3 Coloring and drawing , Dirksen 2002, p. 171.
  6. ↑ 4. Results, 4.1.5 Distribution: Eunectes sp. , Dirksen 2002, p. 46.
  7. ↑ a b 5. Discussion, 5.1.5 Distribution: Eunectes sp. , Dirksen 2002, p. 85.
  8. ↑ 6. Synopsis of the genus Eunectes, 6.4.4 Eunectes beniensis sp. nov., 6.4.4.9 Reproduction & 6.4.4.10 Food & 6.4.4.11 Behavior , Dirksen 2002, pp. 173–174.
  9. ↑ 6. Synopsis of the genus Eunectes, 6.4.1 Eunectes deschaeunseei DUNN & CONANT, 1936, 6.4.1.2 Etymology and common names , Dirksen 2002, pp. 104-105.
  10. ↑ 6. Synopsis of the genus Eunectes, 6.4.4 Eunectes beniensis sp. nov., 6.4.4.2 Etymology and common names , Dirksen 2002, p. 171.
  11. ↑ 6. Synopsis of the genus Eunectes, 6.2 Zur Systematik , Dirksen 2002, pp. 101-103.

Web links

Commons : Beni-Anakonda  - collection of images, videos and audio files