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Reptilia, Viperidae, Crotalinae, Porthidium
nasutum: distribution extension and remarks on
its range and records.
Diego F. Cisneros-Heredia1
Mario Yánez-Muñoz2
1College of Biological and Environmental
Sciences, Universidad San Francisco de Quito,
Casilla Postal 17-12-841, Quito, Ecuador. e-mail:
2División de Herpetología, Museo Ecuatoriano de
Ciencias Naturales, Calle Rumipamba y Ave. de
Los Shyris. Quito, Ecuador.
Porthidum nasutum inhabits the humid lowlands of
Middle America and adjacent northwestern South
America from Mexico (Chiapas) southward to
Ecuador (Manabí) (Porras et al. 1981, Schätti and
Kramer 1993, Campbell and Lamar 2004,
Cisneros-Heredia 2004). In Ecuador, it has been
reported in the provinces of Esmeraldas, Imbabura,
Pichincha, and Manabí, where it inhabits the
lowland rainforest, tropical moist forest, and lower
montane wet forest of the Chocó region (Porras et
al. 1981, Campbell and Lamar, 2004, Pérez-Santos
and Moreno 1991, Schätti and Kramer 1993).
Herein we report a southern extension in the
distribution range of Porthidium nasutum.
Localities and their geographic coordinates and
elevations were determined from researchers’ field
notes, and museum records, and revised according
with a physical map of the Republic of Ecuador
(IGM 2000).
A specimen of Porthidium nasutum deposited at
the Museo Ecuatoriano de Ciencias Naturales
(DHMECN 068) was collected at the Cerro San
Sebastían, Machalilla National Park (ca. 01º36’ S,
80º42’ W, 750 m a.s.l.), province of Manabí, on
September 1991 (Figure 1). It represents the
southernmost record of the species, extending its
range ca. 105 km S from the closest known locality
(11 km W of Bahía de Caráquez, Cisneros-Heredia
2004) (Figure 1). Cerro San Sebastian is a small
hill covered by foothill evergreen and low montane
cloud forest. This population of P. nasutum
appears fairly isolated from other populations of
the species by surrounding dry forest.
The specimen reported by Cisneros-Heredia (2004)
was the first report of the species from the
province of Manabí and it is the same animal
pictured by Campbell & Lamar (2004: Fig. 736).
However the information accompanying Figure
736 erroneously cited the specimen number as
“FHGO-live 698” and the locality as “Kilometer 5,
Bahía-Santo Domingo de los Colorados road,
Manabí, Ecuador, elevation 56 m”.
Another specimen, deposited at the Fundación
Herpetológica G. Orcés (FHGO 1256), collected at
the Jordán River, near Golondrinas (ca. 00°21’ N,
79°02’ W, 280 m a.s.l.) on 06 July 1995,
represents the second known locality of the species
from the province of Imbabura. The species was
otherwise known in the province just from
Paramba (Schätti & Kramer 1993, Cisneros-
Heredia 2004) (Figure 1).
Figure 1. Localities mentioned in the text on the
distribution of Porthidium nasutum in Ecuador.
Provinces are encoded on letters and localities on
numbers. E = Esmeraldas, M = Manabí, G =
Guayas, P = Pichincha, R = Los Ríos, C =
Cotopaxi. 1 = Paramba, 2 = Río Jordán, 3 = Santo
Domingo Area, 4 = 11 km W of Bahía de
Caráquez, 5 = Cerro San Sebastián.
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The distribution of Porthidium nasutum as
currently understood reaches its southernmost limit
along the northern region of the province of
Manabí and in the Santo Domingo de Los
Colorados area in the province of Pichincha
(Porras et al. 1981, Cisneros-Heredia 2004, this
paper). Its distribution seems to be related with the
extension of the Unseasonal Evergreen Forests of
western Ecuador (Porras et al. 1981, D.F.
Cisneros-Heredia pers. obs., see Anderson & Jarrín
2002 for definition of Unseasonal Evergreen
Forests), as both localities in Manabí (Bahía de
Caráquez and Cerro San Sebastián) are at the
contact zone of Unseasonal Evergreen Forests and
Seasonally Dry Forests lower 300 m.a.s.l.
Although in Central America P. nasutum invades
xeric habitats, the species does not seem to invade
dry areas in Ecuador, where Porthidium arcosae
occurs (Campbell & Lamar 2004, D.F. Cisneros-
Heredia pers. obs.).
Towards the slopes of the Cordillera de Los Andes,
the Unseasonal Evergreen Forests extends down to
the provinces of Guayas and Cotopaxi. Because no
barriers are known to restrict the dispersion of
Porthidium nasutum into southern Unseasonal
Evergreen Forests near the slopes of the Andes, it
is very probable that the species will be recorded in
the near future in Guayas and Cotopaxi provinces.
We are grateful to Hernán Román for collecting
the MECN specimen herein reported, to Jean-Mark
Touzet and Ana Ma. Velasco for access to FHGO
material, to Marco Altamirano, director of MECN,
for support and encouragement, and to María Elena
and Laura Heredia for financial and moral support.
Museo Ecuatoriano de Ciencias Naturales and
Universidad San Francisco de Quito provided
institutional support and laboratory space.
Literature Cited
Anderson, R. P. and P. Jarrín. 2002. A New
Species of Spiny Pocket Mouse
(Heteromyidae: Heteromys) Endemic to
Western Ecuador. American Museum
Novitates 3382: 1-26.
Campbell, J. A. and W. W. Lamar. 2004. The
Venomous Reptiles of the Western
Hemisphere. Ithaca, Comstock Publ. Assoc.,
Cornell Univ. Press. 870 pp.
Cisneros-Heredia, D. F. 2004. Porthidium
nasutum. Geographic Distribution.
Herpetological Review 35(3): 293.
IGM. 2000. Republica del Ecuador, Mapa Físico,
1:1’000.000. Instituto Geogr’afico Militar,
Pérez-Santos, C. and A. G. Moreno. 1991.
Serpientes de Ecuador. Mus. Reg. Sci. Nat.
Monogr. 11:1-538.
Porras, L., J. R. McCranie and L. D. Wilson. 1981.
The Systematics and Distribution of the
Hognose Viper Bothrops nasuta Bocourt
(Serpentes: Viperidae). Tulane Studies in
zoology and Botany 22: 85-107.
Schätti, B and E. Kramer. 1993. Ecuadorianische
Grubenottern der Gattungen Bothriechis,
Bothrops und Porthidium (Serpentes:
Viperidae). Revue Suisse de Zoologie 100(2):
Received May 2005
Accepted October 2005
Published online October 2005
After a snakebite accident, species identification is of vital importance. However, the existence of intraspecific differences in the body coloration patterns of venomous snakes can generate confusion and delay a convenient and effective treatment. This is the situation for Porthidium lansbergii lansbergii from Colombia, for which two distinctive color morphs occur, and the relationship of these morphs with venom toxicity is unknown. Therefore, venom samples from specimens of these two morphs were collected from the Colombian Caribbean region, and their protein profiles compared. Likewise, their venom functional activities were evaluated in vitro and in vivo in BALB/C mice. Additionally, using sequences of the mitochondrial cytochrome b (Cyt-b) gene, the relationship between these Colombian P. lansbergii lansbergii morphotypes was investigated, and their phylogenetic positions were determined for the first time using Bayesian inference. Despite the noticeable coloration divergence between the individuals analyzed, similar protein profiles of their venoms were observed. Additionally, neither their lethality nor biochemical activities were notably different. In general, both venoms were highly proteolytic, lacked a coagulant effect in vitro, and extended the clotting time due to the action of venom components, such as disintegrins and proteases, that induce defibrination. These results agreed with the result of our phylogenetic analysis, suggesting that the two chromatic morphs do not represent isolated populations. The phylogenetic analyses also supported the currently recognized P. lansbergii lansbergii subspecies as a monophyletic complex. In conclusion, the results of this investigation suggest similar clinical manifestations regardless of body coloration after a P. lansbergii lansbergii envenomation, and pools can therefore be used for antivenom development, medical treatments, and further research efforts.
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