Agentine Hognose or Falsa Yarará (Lystrophis d. uruguayensis)

Species:

Synonyms:

Common name:

Subspecies:

Family:

Colubridae

DISTRIBUTION:

S-Paraguay, S-Brazil (Rio Grande do Sul), C-Argentina (Chaco, Corrientes, Misiones, Entre Rios, Buenos Aires, Rio Negro, La Pampa, Santa Fe, Córdoba, Santiago del Estero), Uruguay

HABITAT:

As with its North American cousins, South American Lystrophis prefer sandy soils with shortgrass growth. All members of Lystrophis are burrowers and spend much of their time beneath the surface in search of amphibians, lizards, their eggs, and larvae.

PREDATORS:

The main natural predators of Lystrophis dorbignyi are coatíe mundis, mustelids (weasels and ferrets), wild cats and raptors such as hawks, owls, and eagles, in addition to other snakes such as coral snakes and musuranas.

DEFINITION

Members of the Genus Lystrophis belong to the Subfamily Xenodontinae. As with other xenodontids, Yararas possess large, bladelike posterior maxillary teeth, a large adrenal gland, and several other characters similar to venemous opisthoglyphs. However, two of the genera, Lystrophis and Heterodon, have pointed, recurved, digging snouts not seen in Xenodon.

Overall, Lystrophis dorbignyi is a small, heavy bodied species with males reaching up to 560mm including 80mm tail. Females have measured up to 610mm. . The ground color is brown, brownish grey or tan. A series of 20 or more grayish brown, deep cinnamon, or chocolate brown dorsal blotches occur on the dorsum and alternate with rows of smaller, similarly colored spots and reddish brown spots on the sides. The head pattern consists of a dark band across the posterior azygous scales, the anterior edge of the frontals, and the supraoculars, as well as a broad dark band from the eye to the angle of the mouth. A middorsal and two lateral elongated nuchal blotches extend forward to the parietal scales. The venter usually consists of alternating black and red bands extending to the tail which it uses as part of its defense. The scales number 21 at midbody.

This snake is also frequently confused with Waglerophis merremi which is a rear fanged snake also found locally in regions where Lystrophis dorbignyi is known. Like Lystrophis dorbignyi, when confronted by predators, W. merremi adopts a similar stance to local vipers; it widens his body, flattening it, and straightens its neck, lifting it up off the ground, and spreads a false hood, giving it the appearance of having a triangular head. If the threat continues, the snake coils its body, with its head in the center, opens its mouth wide and shakes its tail while striking repeatedly. This behavior is extremely similar to American hognosed snakes.

BEHAVIOR

This inoffensive snake owes its common name to to its display of colors typical of highly venomous species like yaras, cruceras ((Bothrops alternatus (Yanosky & Chani 1988)) & coral snakes (Micrurus). These snakes are most active during the spring (November) breeding season and fall rains (February), either in search of a mate or food respectively.
South American hognosed snakes are entirely inoffensive and will not bite unless seriously provoked. When handled the snake may actually gape at the attacker, spread a small hood, and hiss loudly. Although rear fanged, the toxicity of its venom is unkown. Breeding season begins in September with parturition occurring from November to December whereupon the snake lays approximately 10 to 14 eggs, which hatch in January or February. . The eggs range in diameter of 14 to 27mm. Commonly preyed upon by raptors, small mammals and ophiophagus (snake eaters) snakes.

CHARACTERISTICS

As with other hognoses, if cornered, Lystrophis dorbignyi spreads it neck, creating a small hood, inflates its body and curls the end of its tail into a ring, showing the red and black banded ventral color. Lystrophis dorbignyi will also hiss loudly and emit a foul smelling odor.

FEEDING BEHAVIOR

Lystrophis dorbignyi feeds on small amphibians & reptiles including reptile eggs, and as neonates, occasionally insects.

REFERENCES

Bailey, Joseph R. 1962 Lystrophis Cope, 1885 (Reptilia): Proposed validation under the plenary powers. z.n.(s.) 1484 Bulletin of Zoological Nomenclature 19 3 164-169

DUMÉRIL, A.M.C., G. BIBRON & A.H.A. DUMÉRIL (1854)
Erpétologie générale ou Histoire Naturelle complète des Reptiles. Vol. 7 (partie 1). Paris, xvi + 780

S. de Lema, Th. (1994) Lista comentada dos répteis occorentes nor Rio Grande do Sul, Brasil. Comun. Mus. Cienc. Tecnol. PUCRS, Sér. Zool., Porto Alegre 7: 41-150

Yanosky, A.A., J.M. Chani. 1988. Possible Dual Mimicry of Bothrops and Micrurus by the Colubrid, Lystrophis dorbignyi. Journal of Herpetology. 22 (2):222-224.