Agkistrodon Howardgloydi

''Agkistrodon howardgloydi'' is a species of venomous snake, a pit viper ( Crotalinae), that is endemic to Central America. It is most commonly called castellana,Conant, R. 1984. ''A new subspecies of the pit viper Agkistrodon bilineatus (Reptilia: Viperidae) from Central America.'' Proceedings of the Biological Society of Washington. 97: 135-141.Gloyd, H. K., and R. Conant. 1990. ''Snakes of the Agkistrodon Complex: A Monographic Review.'' Society for the Study of Amphibians and Reptiles, Contributions in Herpetology, Number 6. Ithaca, New York, USA. Savage, J. M. 2002. ''The Amphibians and Reptiles of Costa Rica, A Herpetofauna between Two Continents, between Two Seas.'' University of Chicago Press, Chicago, Illinois. xx, 934 pp. but it has also been called the southern cantil,Porras, L.W., L. D. Wilson, G. W. Schuett, R. S. Reiserer. 2013. ''A taxonomic reevaluation and conservation assessment of the common cantil, Agkistrodon bilineatus (Squamata: Viperidae): a race against time.'' Amphibian & Reptile Conservation 7(1): 48–73. Gloyd's moccasin, and a number of other colloquial names. It is a rare species with a relatively small geographic distribution in the tropical dry forest on the Pacific coast of Honduras, Nicaragua, and extreme northwest Costa Rica.Porras, L.W., L. D. Wilson, G. W. Schuett, R. S. Reiserer. 2013. ''A taxonomic reevaluation and conservation assessment of the common cantil, Agkistrodon bilineatus (Squamata: Viperidae): a race against time.'' Amphibian & Reptile Conservation 7(1): 48–73. ''Agkistrodon howardgloydi'' is a stout, medium-sized snake with a maximum length of 96 cm. It is a viviparous species, with female giving birth in the rainy season from May to August.Campbell, J. A., and W. W. Lamar. 2004. ''The Venomous Reptiles of the Western Hemisphere (Vol. I & II).'' Comstock Publishing Associates, Cornell University Press, Ithaca, New York, USA. No clinical reports on envenomation had been published (as of 1999), but laboratory texts and analysis indicate the venom is highly toxic and similar to its close relative ''Agkistrodon bilineatus'', and potentially lethal.Sloórzano, Alejandro.Marjorie Romero, José Maria Gutierrez, and Mahmood Sasa. 1999. ''Venom composition and diet of the cantil Agkistrodon bilineatus howardgloydi (Serpentes: Viperidae).'' Southwestern Naturalist, 44(4): 478-483.

Etymology

Roger Conant's original description states: "This subspecies is named for the late Howard K. Gloyd, my close friend, colleague, and expert on pit vipers, especially the rattlesnakes. Gloyd worked for decades on the genus '' Agkistrodon'' ('' sensu lato''), and he had predicted that a new race of '' A. bilineatus'' would eventually be described from lower Central America."Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiii + 296 pp. . (''Agkistrodon bilineatus howardgloydi'', pp. 102, 126).

The common name castellana is the feminine form of castellano, translating to Castilian, or Spaniard, but it is not entirely clear how this name came to be applied to ''A. howardgloydi''. It has been speculated that it is something of an analogy, with the snake and the conquistadores being equally feared, or the snake and the conquistadores both being alert and ready to strike in a confrontation.

Taxonomy and Phylogenetics

The molecular evidence indicates the genus '' Agkistrodon'' is a monophyletic group, with the copperheads, ('' A. contortrix'' and '' A. laticinctus'') the most basal (ancestral) lineage of the genus, the cottonmouths ('' A. piscivorus'') basal to the four cantil species, Taylor's cantil ('' A. taylori'') basal to the common cantil ('' A. bilineatus''), which is basal to the Yucatecan cantil ('' A. russeolus'') and the castellaana (''A. howardgloydi''). Both molecular and morphological evidence indicate that ''Agkistrodon howardgloydi'' and ''Agkistrodon russeolus'' are more closely related to each other ( sister taxa) than ''Agkistrodon bilineatus'' or ''Agkistrodon taylori''.Parkinson, C. L., K. R. Zamudio, and H. W. Greene. 2000. Phylogeography of the pitviper clade Agkistrodon: historical ecology, species status and conservation of cantils. Molecular Ecology 9: 411-420.

In 1984, while preparing a monograph on the genus ''Agkistrodon'', and after examining virtually all museum specimens of ''Agkistrodon'' from Central America known at that time, Roger Conant described ''Agkistrodon bilineatus howardgloydi'' as a subspecies of the common cantil (''Agkistrodon bilineatus''). In the following 30 years, subsequent accounts supported recognition of the subspecies. In a 2013 taxonomic reevaluation, all three subspecies of ''Agkistrodon bilineatus'' were elevated to full species (''Agkistrodon bilineatus'', ''Agkistrodon russeolus'', and ''Agkistrodon howardgloydi'') based on morphology, biogeography, and consideration of previous DNA-based studies.

Description

Of the ten specimens of ''A. howardgloydi'' available to Gloyd and Conant (1990) from Nicaragua and Costa Rica, the largest male was and the largest female in total length (including tail). According to Villa (1984), adults in Nicaragua almost never exceed in length. In both sexes, the tail length is 19% of the total body length.

Scalation includes 23 rows of keeled dorsal scales at midbody; 128-135 ventral scales; and 54-61 subcaudal scales, roughly half of which are paired, especially towards the tail tip.

The dorsal color pattern consists of light to medium reddish brown ground color overlaid with 10-14/13-17 broad brown or brownish crossbands in males/females. Large adult males tend to be melanistic. Juveniles are more lightly colored, even to the point of being bright red. The head is clearly marked on either side with two longitudinal light lines: the upper one is narrow and broken or even absent posterior to the supraocular scale; while the lower one is wider and split into two parts which may or may not meet at the suture of the third supralabial scale.

''Agkistrodon howardgloydi'' can be distinguish from other members of the genus '' Agkistrodon'' by the presence of a loreal scale (absent in cottonmouths '' A. piscivorus'' and '' A. conanti''), and two distinctive white or light stripes on each side of the face (absent in copperheads A. contortrix and '' A. laticinctus''). It can be distinguish from the other cantils by several moderately subtle markings on the head. Among the more obvious are the lower light stripes which are noticeably angled below the pit (at the seam of the second and third supralabials) appearing as a dip or small gap in the stripe (only rarely seen in '' A. russeolus'', otherwise lower light stripe more or less straight or gently curved, running evenly and unbroken from the snout to the back of the mouth in other cantils). The bottom side of the head, chin and throat area, is orange or orange-brown and distinctly lighter than the ventral scales which abruptly turn darker on the neck and body.

Distribution

''Agkistrodon howardgloydi'' is found on the Pacific coast of Nicaragua, ranging north into the Gulf of Fonseca area in extreme southwest Honduras, and south into the Guanacaste Province of extreme northwest Costa Rica. It occurs on a relatively narrow strip of lowlands less than 400 km. north to south. The elevational range is from near sea level to no more than 600 m. In Costa Rica it has been reported from 20 to 285 m., and sea level to 300 m. elevation.Sloórzano, Alejandro. 2004. ''Snakes of Costa Rica: Distribution, taxonomy, and natural history.'' Institioto Nacional de Biodiversidad. Santo Domingo de Heredia, Costa Rica. 791 pp. The type locality given is "0.8 km north Mirador el Cañon del Tigre, Parque Nacional Santa Rosa, Provincia Guanacaste, Costa Rica".

Diet

Fish, frogs, lizards, birds, eggs, and rodents were identified in the diet of ''A. howardgloydi'' in one Nicaraguan publication. A study conducted early in the rainy season of 1994 in Costa Rica found some age related variation in the diet: neonates (<38cm.) contained frogs ('' Hypopachus'') and lizards (''Marisora'', ''Holcosus''); juveniles (38-50 cm.) contained frogs ('' Leptodactylus''), lizards ('' Ctenosaura''), and mice (''Liomys''); adults (>50 cm.) contained lizards ('' Ctenosaura''), mice (''Liomys''), and rats ('' Sigmodon''), suggesting an ontogenetic shift in diet from ectotherm prey in juveniles, to endotherm prey in adults. .

Conservation

In a 2013 conservation assessment, ''A. howardgloydi'', was considered endangered (although this assessment had no political or legal standing), and using the Environmental Vulnerability Score (EVS) ow, 3–9; medium, 10–13; high, 14–20 ''Agkistrodon howardgloydi'' was rated 17, a species of high vulnerability. ''Agkistrodon howardgloydi'' is a rare species throughout most of its limited range. The lowland dry forests have been among the most severely impacted vegetation zones in Mesoamerica, with four centuries of clearing for farming and ranchland leaving very little of the original vegetation intact. Efforts to locate the species in the Gulf of Fonseca area in Honduras in the late 1990s were unsuccessful and it was concluded that population densities there were very low, or possibly even extirpated from the area. Only in a few remote, protected areas in Costa Rica was ''A. howardgloydi'' still reported to be observed with some regularly at the end of the 20th century.

Colloquialisms and folklore

The name cantil is applied to all ''Agkistrodon'' on the Pacific coast from Mexico to Costa Rica. Likewise, vibora castellana is another name used for both ''Agkistrodon bilineatus'' and ''A. howardgloydi'' on the Pacific coast of Guatemala to Costa Rica. In Nicaragua the names bil palka, dimuih palka, castellana de jáquima, charquera, and toboba have all been used for the species.

References

Further reading

* Conant R (1984). "A new subspecies of the pit viper ''Agkistrodon bilineatus'' (Reptilia: Viperidae) from Central America". ''Proc. Biol. Soc. Wash.'' 97: 135–141. (''Agkistrodon bilineatus howardgloydi'', new subspecies).
*Porras, Louis W.; Wilson, Larry David; Schuett, Gordon W.; Reiserer, Randall S. (2013).
A taxonomic reevaluation and conservation assessment of the common cantil, ''Agkistrodon bilineatus'' (Squamata: Viperidae): a race against time
. ''Amphibian & Reptile Conservation'' 7 (1): 48–73. (''Agkistrodon howardgloydi'', new status, p. 60). (in English with an abstract in Spanish).
*Villa JD (1984). "The venomous snakes of Nicaragua: a synopsis". ''Contributions in Biology and Geology, Milwaukee Public Museum'' 59: 1–41.

External links

*

howardgloydi
Reptiles described in 1984

{{Alethinophidia-stub