Snakes long-lost

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Alternate title suggested by Mike Pingleton: Not all who slither are lost

Clarión Nightsnake (Hypsiglena unaocularis)
Photograph from Mulcahy et al. 2014

Just over one year ago, a team of scientists from the Smithsonian and the Red de Interacciones Multitróficas rediscovered a species of nightsnake (genus Hypsiglena) on remote Clarión Island in the eastern Pacific Ocean, over 400 miles southwest of Cabo San Lucas. Called the Clarión Nightsnake (Hypsiglena unaocularus), it was originally discovered by the renowned American naturalist William Beebe in 1936, during a nocturnal sea turtle nesting survey. Because Clarión Island is only accessible via military escort, biologists have not visited the island frequently since Beebe's time, and in 1955 herpetologist Bayard Brattstrom suggested that perhaps Beebe's locality information had been an error, since only a single specimen existed and several other Clarión Island expeditions had not turned up another. However, the type specimen collected by Beebe, resting in the herpetology collection of New York's American Museum of Natural History, was sufficiently distinct from any other Hypsiglena specimen that it prompted herp phylogeographer Dan Mulcahy to reexamine Beebe's book and field notes, which contained a pretty clear description of the circumstances under which Beebe found the snake:

“We walked on, flashing the light all around. Not far from the water on the black lava 

I saw a small dark brown snake. It seemed to be unlike the one I had found in daylight, 

having lines of black spots on the body, so I picked it up and cached it in my shirt.” 

(p. 282 of Zaca Venture)

Location of Clarión Is.
From Mulcahy et al. 2014
Click to enlarge

As their name implies, Nightsnakes mostly come out at night (although I found one in southern Utah at about 9:30 in the morning a few weeks ago), and even then they are normally only active under certain conditions - in particular, they prefer to be active when there is not much moonlight, such as on cloudy nights or when the moon is new. Even if one is specifically searching for Nightsnakes, they can be difficult to find. Combined with their generally secretive nature, this could explain the failure of several Clarión Island expeditions to find the Clarión Nightsnake - until Mulcahy's expedition in May of 2013, which found 11 individuals in 15 days. Using phylogenetics, they determined that the Clarión Nightsnake is most closely related to the Santa Catalina Nightsnake (H. catalinae), which is found on Santa Catalina Island in the Gulf of California (which is not the same as the well-known Santa Catalina Island off of the US state of California). Nightsnakes are found all around the shoreline of the Gulf of California, and they are obviously exceptional over-water dispersers, because they occur on many of the islands in that region as well.

This remarkable story of rediscovery is a testament to the kind of attention to detail that it takes to be a good natural historian, but it's not the only species of snake that has been rediscovered many years after its initial description. Here are a few others:

Angel’s Stream Snake (Paratapinophis praemaxillaris)
Photograph from Murphy et al. 2008

Angel’s Stream Snake (Paratapinophis praemaxillaris) was described from two newborn specimens from northern Laos in 1929. At that time it was placed into a new genus because of an unusual process on its nose, but a few years later it was moved into the cosmopolitan genus Opisthotropis. Two more specimens were collected in the 1980s, but it wasn't until 2008, when five adult specimens were collected from a pool at the base of a waterfall on the Nan River in northern Thailand, that it became clear that the nose structure was actually an egg tooth, a structure normally lost a few days after hatching. At that time, Paratapinophis was placed back into its own genus because of several other formerly-overlooked unique features, including sexually dimorphic color, pattern, and scale ornamentation. Like most other natricines, this species eats fishes.

Chersodromus rubriventris
Photograph from Ramírez-Bautista et al. 2013

Chersodromus rubriventris, the Redbelly Earth Runner, was discovered in a cloud forest in San Luis Potosí, Mexico, just after the end of World War II and described a few years later by American herpetologist and spy Edward H. Taylor, who also used his biology as a cover for work in the Philippines, Russia, and Sri Lanka during both world wars. Two other specimens, one from the late 1960s and the other from the early 1980s, were known, but in 2013, a team of herpetologists from the Universidad Autónoma del Estado de Hidalgo found three individuals in a cloud forest in nearby Hidalgo, doubling the number of specimens and photographing the snake alive for the first time. Stomach contents included beetle larvae and ants, both of which are unusual prey for a dipsadid snake.

Atractus wagleri
Photograph from Passos & Arredondo 2009

The genus Atractus, a group of burrowing snakes found from Panama to Argentina, is the most diverse alethinophidian snake genus, with over 130 species, most of which are only known from a few specimens. Recently Paulo Passos of the Brazilian National Museum matched up several previously mis- or unidentified Atractus specimens in South American museums with their species, constituting rediscoveries of sorts. For example, Wagler's Ground Snake (Atractus wagleri) was described in 1945 from a single specimen from western Colombia, and that specimen was lost in a fire in 1948. In 2009 Passos located three additional specimens of this poorly known snake in museums in Colombia. Another species, the Modest Ground Snake (Atractus modestus), was described in 1894 by the great Belgian zoologist George Boulenger, from a single specimen from western Ecuador. In 2007 Passos located more specimens in Ecuadorian museums, expanding the range of the species across most of the country. Although species of Atractus are seemingly quite rare, occurring at high elevations and having secretive fossorial habitats, a large number of Atractus specimens remain misidentified or unidentified in herpetological collections, so our knowledge of these snakes stands to improve dramatically as these are examined and described.

Argus Snail Sucker (Sibon argus)

The Lichen-coloured or Argus Snail Sucker (Sibon argus) is an extremely slender arboreal dipsadine snake with eye-like ("ocellate") spots. It was originally described from a single specimen from southeastern Costa Rica in 1876, by renowned paleontologist Edward Drinker Cope (who feuded with O.C. Marsh in the "Bone Wars" over who could discover more dinosaurs, the subject of an upcoming film starring Steve Carrell as Cope). The validity of the species was uncertain because of the subsequent description of other gracile snakes with ocellated patterns from the same region. In his classic revision of Neotropical snail- and slug-eating snakes, James Peters suggested that Cope's specimen might be aberrant, or perhaps that it represented one half of a species with strong sexual dimorphism (which is rare in snakes), because the only known S. argus specimen  was a male, and another species, Sibon longifrenis, was known at the time from just two specimens, both females. Males and females of the same species had been described as separate species before. Ultimately, Peters decided that the two species were probably different, and he was proven right in 1992, when tropical herpetologist Jay Savage was preparing his opus on Costa Rican herpetofauna. Savage discovered both male and female specimens that best matched Cope's 1876 S. argus in the collections of the University of Kansas and the Universidad de Costa Rica. The snakes had been collected in evergreen forests in Panama and Costa Rica, near the type locality of S. argus. With Roy McDiarmid, Savage redescribed the species, which has become much more well-known since. A recent study by Julie Ray and colleagues documented a more diverse diet for this species than previously expected, including other gooey prey such as oligochaete worms and frog eggs. Unfortunately for Sibon argus, both of these prey types are in decline in the neotropics, the worms due to overcollection of their bromeliad homes for horticulture, and the amphibians due to the devastating effects of the amphibian chytrid fungus Batrachochytrium dendrobatidis.

Brygophis coulangesi
Photograph from Andreone & Raxworthy 1998

Other examples of rediscovered snakes abound. The Uluguru Worm Snake (Letheobia uluguruensis) was described from four specimens collected in 1926 from the Uluguru Mountains of eastern Tanzania, a mountain range with dozens of endemic species, and was not seen again until 2004, when four were dug up by local people employed by a group of herpetologists from the London Natural History Museum and the University of Glasgow to search for caecilians. Another blindsnake, Typhlops tasymicris, was rediscovered on Union Island, St. Vincent and the Grenadines, in 2010. An entire genus of blindsnake, Xenotyphlops, was rediscovered in Madagascar, in 2007, 102 years after it's description. A rare sea snake, Hydrophis parviceps, was originally collected by the Danish research vessel Dana and described in 1935 and was seen again only once in 1960 until three turned up in fisheries bycatch off of Vietnam in 2001. Another species of rare sea snake, H. bituberculatus, was rediscovered off Sri Lanka in the late 1980s, over 100 years after the first one was collected (although the fishermen who collected the specimen were so secretive that they refused to divulge the location). One of the rarest snakes in Madagascar, a slow-moving reddish-orange species called Brygophis coulangesi, was first collected in 1968, when one fell from a tree and vomited up a chameleon, with a second specimen found on a cloudy, rainy night during a rain forest survey in 1998, over 300 miles to the north of the first. A second specimen of another Malagasy lamprophiid, Alluaudina mocquardi, was discovered in a pitch-black cave in northern Madagascar in 1982, 50 years after the first was found in a different cave nearby. I don't think any more have been found since, so this one should be getting ready to be rediscovered again soon (edit: City University of New York snake biologist Frank Burbrink informed me that on his recent trip to Madagascar they turned up an Alluaudina mocquardi in tsingy rock at Ankarana - see photo here)!

March 2010 Herp. Review cover
featuring Crotalus lannomi

A high-profile rediscovery graced the cover of the March 2010 issue of the journal Herpetological Review, which featured a photograph of a long-sought-after species of rattlesnake, the Autlán Long-tailed Rattlesnake (Crotalus lannomi). Discovered in the summer of 1966 by Joseph Lannom, C. lannomi became sort of a “holy grail” of rattlesnakes in the decades that followed, as numerous herpetologists ventured into the mountains of western Jalisco in search of it. They were stymied by heavy fog and dangerous flooding, roads with treacherous curves and highway robberies, and drug-related violence. In 2008, five specimens of C. lannomi were found in the foothills of Colima, roughly 50 km from the type locality in Jalisco, in some of Mexico's most pristine forest habitat.

Although most of this was new to me, I've actually written about a different rediscovered viper before, the Spider-tailed Adder (Pseoducerastes urarachnoides) of Iran, which was discovered in 1968 and was at first thought to have either a tumor, a congenital defect, or a growth caused by a parasite, or maybe a spider clinging to its tail (turns out its tail is modified into a lure to attract spider-eating birds). Also, in one of my first articles, I wrote about the South Florida Rainbow Snake (Farancia erytrogramma seminola), described by Wilfred T. Neill in 1964 from Fisheating Creek in Glades County near Lake Okeechobee, Florida, and presumed extinct, never seen again since. To the best of my knowledge this subspecies has yet to be rediscovered, despite a $500 reward from the Center for Snake Conservation and Center for Biological Diversity. (Edit: a diligent reader reminded me that I also wrote about another snake that hasn't been seen since 1975 in one of my earliest articles, the Round Island Burrowing Boa, Bolyeria multocarinata).

Undoubtedly there are numerous snake species left to be discovered and rediscovered, and in many cases almost nobody's out there looking. The Reptile Database has predicted that the total number of described reptile species will surpass 10,000 in 2014, and that non-avian reptiles will perhaps eclipse birds in diversity soon after that. With snakes currently at 3,466, representing just over one third of reptiles, maybe you will be the next to rediscover a snake thought lost!

ACKNOWLEDGMENTS

Thanks to Dan Mulcahy and Don Filipiak for the use of their photographs.

REFERENCES

Andreone, F. and C. Raxworthy. 1998. The colubrid snake Brygophis coulangesi (Domergue 1988) rediscovered in north-eastern Madagascar. Tropical Zoology 11:249-257 <link>

Beebe, CW. 1938. Zaca Venture. Harcourt, Brace and Co. Inc., New York <link>

Cope, E. D. 1875. On the batrachia and reptilia of Costa Rica : With notes on the herpetology and ichthyology of Nicaragua and Peru. Journal of the Academy of Natural Sciences Philadelphia 2:93-157 <link>

Gower, D. J., S. P. Loader, and M. Wilkinson. 2004. Assessing the conservation status of soil‐dwelling vertebrates: Insights from the rediscovery of Typhlops uluguruensis (Reptilia: Serpentes: Typhlopidae). Systematics and Biodiversity 2:79-82 <link>

Lanza, B. 1990. Rediscovery of the Malagasy colubrid snake Alluaudina mocquardi Angel 1939. Tropical Zoology 3:219-223 <link>

Mulcahy, D. G., J. E. Martínez-Gómez, G. Aguirre-León, J. A. Cervantes-Pasqualli, and G. R. Zug. 2014. Rediscovery of an endemic vertebrate from the remote Islas Revillagigedo in the eastern Pacific Ocean: The Clarión Nightsnake lost and found. PLoS ONE 9:e97682 <link>

Mulcahy, D. G. and J. R. Macey. 2009. Vicariance and dispersal form a ring distribution in nightsnakes around the Gulf of California. Molecular Phylogenetics and Evolution 53:537-546 <link>

Murphy, J. C., T. Chan-Ard, S. Mekchai, M. Cota, and H. K. Voris. 2008. The rediscovery of Angel’s Stream Snake, Paratapinophis praemaxillaris Angel, 1929 (Reptilia: Serpentes: Natricidae). The Natural History Journal of Chulalongkorn University 8:169-183 <link>

Passos, P. and J. C. Arredondo. 2009. Rediscovery and redescription of the Andean earth-snake Atractus wagleri (Reptilia: Serpentes: Colubridae). Zootaxa 1969:59-68 <link>

Passos, P., D. F. Cisneros-Heredia, and D. Salazar-V. 2007. Rediscovery and redescription of the rare Andean snake Atractus modestus. The Herpetological Journal 17:1-6 <link>

Peters, J. A. 1960. The snakes of the subfamily Dipsadinae. Miscellaneous Publications of the Museum of Zoology, University of Michigan 114:1-228 <link>

Ramírez-Bautista, A., C. Berriozabal-Islas, R. Cruz-Elizalde, U. Hernández-Salinas, and L. Badillo-Saldaña. 2013. Rediscovery of the snake Chersodromus rubriventris (Squamata: Colubridae) in cloud forest of the Sierra Madre Oriental, México. Western North American Naturalist 73:392-398 <link>

Rasmussen, A. R. 1992. Rediscovery and redescription of Hydrophis bituberculatus Peters, 1872 (Serpentes: Hydrophidae). Herpetologica 48:85-97 <link>

Rasmussen, A. R., J. Elmberg, K. L. Sanders, and P. Gravlund. 2012. Rediscovery of the rare sea snake Hydrophis parviceps Smith 1935: identification and conservation status. Copeia 2012:276-282 <link>

Ray, J. M., C. E. Montgomery, H. K. Mahon, A. H. Savitzky, and K. R. Lips. 2012. Goo-eaters: Diets of the Neotropical snakes Dipsas and Sibon in central Panama. Copeia 2:197-202 <link>

Reyes-Velasco, J., C. I. Grünwald, J. M. Jones, and G. N. Weatherman. 2010. Rediscovery of the rare Autlán Long-tailed Rattlesnake, Crotalus lannomi. Herpetological Review 41:19-25 <link>

Rodríguez, M. J. R., E. J. Bentz, D. P. Scantlebury, R. R. John, D. P. Quinn, J. S. Parmerlee Jr, R. W. Henderson, and R. Powell. 2011. Rediscovery of the Grenada Bank endemic Typhlops tasymicris (Squamata: Typhlopidae). Journal of Herpetology 45:167-168 <link>

Savage, J. M. and R. W. McDiarmid. 1992. Rediscovery of the Central American colubrid snake, Sibon argus, with comments on related species from the region. Copeia 1992:421-432 <link>

Taylor, E. H. 1949. A preliminary account of the herpetology of the state of San Luis Potosí, Mexico. University of Kansas Science Bulletin 33:169-215 <link>

Wallach, V., V. Mercurio, and F. Andreone. 2007. Rediscovery of the enigmatic blind snake genus Xenotyphlops in northern Madagascar, with description of a new species (Serpentes: Typhlopidae). Zootaxa 1402:59-68 <link>

Weaver, R. E. 2010. Activity Patterns of the Desert Nightsnake (Hypsiglena chlorophaea). The Southwestern Naturalist 55:172-178 <link>

Life is Short, but Snakes are Long by Andrew M. Durso is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

Round Island splitjaw snakes

To view this article in Spanish, click here!

Para ver este artículo en español, haga clic aquí!

Adult female Casarea dussumieri

Not to be confused with the unfortunate Round Island burrowing boa (Bolyeria multocarinata), last seen in 1975, the Round Island keel-scaled boa is still with us, although just barely. In 1996, less than 250 adult individuals remained alive, although recent captive breeding efforts have raised that to about 1000. Together, Casarea and Bolyeria made up the strange and intriguing family Bolyeriidae. Although they're sometimes called 'boas', they are distinct from the Boidae, or true boas, in not having any vestiges of a pelvic girdle. In fact, they are more closely related to the advanced snakes (Caenophidia) than to the true boas, although their phylogenetic relationship to other snakes is not quite certain. Some have advocated calling them 'splitjaw snakes' instead of boas. Due to their remote range (and the extirpations they suffered), few herpetologists have been lucky enough to see a living specimen, especially a wild one. I hope to cover what is known about these two species in this short article.

Mauritius and surrounding islets

Round Island is a herpetologically interesting volcanic islet, 151 ha (just over half a square mile) in size, located approximately 22.5 km NNE of Mauritius, in the Indian Ocean east of Madagascar. Round Island and Mauritius are part of the Mascarene archipelago, which formed between 35 and 2 million years ago as a result of the Réunion hotspot. Before the 16th century, no humans inhabited the islands, which were covered in unique tropical moist broadleaf forest. All of the Mascarene flora and fauna arrived by oversea dispersal, possibly using prehistoric islands of the Mascarene plateau, now submerged by the sea, as 'stepping stones'. Round Island is also home to an endemic skink (Leiolopisma telfairii) and an endemic day gecko (Phelsuma guentheri). Both snakes used to be found on Mauritius and other nearby islets, from which they were first extirpated. Microhabitats include fallen palm fronds and the burrows of nesting pelagic birds such as shearwaters. Captive breeding efforts are hindered by the fact that these two endangered lizards constitute the sole natural prey of Casarea, so they must be enticed to eat mice in captivity, which is more easily said than done. A few parasites of the taxon have been described, mostly by Peter Daszak of the EcoHealth Alliance.

What certainly hasn't helped clarify their taxonomy is that relatively few specimens and tissue samples are available for study. Twenty-eight genes have been sequenced for Casarea, but (unsurprisingly) none for Bolyeria, which is represented in museums by only seven specimens. Scientists are understandably reluctant to collect fresh Casarea specimens for study (DNA is far easier to sequence from fresh tissue), and the number of snakes in captivity is relatively few. Only in 2005 did we learn, posthumously, that Bolyeria probably laid eggs, rather than give live birth like many boas.

Casarea dussumieri in captivity

The skull of Casarea, which was described using high-resolution X-ray computed tomography by Masiano & Reippel (2007), is unique in having the maxilla subdivided into two movably jointed parts. That's right - the maxilla - the upper jaw. Snakes are renowned for the highly kinetic skulls, but no other snakes (or vertebrates, for that matter) have a kinetic maxilla. This jaw and its associated musculature are the basis for classifying Casarea and Bolyeria in a family of their own. Other lizard-eating snakes have analogous adaptations for grasping their hard-bodied prey, but no group takes this adaptation to such extremes as the bolyeriids. But think - on an island with no mammals and few birds, with little else but lizards to eat, selection is stronger than anywhere else for adaptations to saurophagy.

High-resolution X-ray computed tomography image of Casarea skull

Juvenile Casarea

Round Island keel-scaled boas reach 1 to 1.5 meters in length. Color changes ontogenetically (with age). According to observations made in captivity, Casarea are primarily nocturnal. Donald McAlpine, a researcher at the Jersey Wildlife Preservation Trust, where captive C. dussumeri are bred and studied, published a paper in 1983 showing data that captive specimens changed color every day, from light at night to dark during the day, reminiscent of another island-living boa, the Hog Island race of Boa constrictor from Cayos Cochinos in Honduras. Physiological color change in snakes has also been documented in the southeast Asian snake Enhydris gyii. Whether the purpose is cryptic, thermoregulatory, or something else entirely, we can only speculate. McAlpine ended his paper with the statement: "Hopefully this interesting phenomenon will be examined before Casarea becomes extinct." McAlpine's paper has been cited only twice, and as far as I can tell no research on this topic has been done since. An expedition to look for Bolyeria in 2001 was unsuccessful.

Painting of Bolyeria - no photos of living animals are known

Update 11/2/2013: I have just learned of an effort by the Mauritius Reptile Recovery Programme to reintroduce Casarea dussumieri to Gunner's Quoin, a nearby island where invasive rats and rabbits have been extirpated and to which the boa’s key prey item, the Telfair’s skink, was reintroduced from Round Island in 2007. In October of 2012, six months after this article was published, 60 C. dussumieri were released on Gunner's Quoin after 150 years of absence. If I learn the results of efforts to monitor this new population, I will post them here.

Update 3/2/2018: Thirteen new juveniles and one adult recapture were found on Gunner's Quoin in November 2015, and 28 snakes (17 of which were not recaptures) were found on Round Island in the same year. Today, conservation biologist Aurelie Hector at the Mauritian Wildlife Foundation & EDGE of Existence/Zoological Society of London/Fondation Segré is surveying the growing Round Island population of Casarea dussumieri monthly and educating children about the snakes. She observed possible predation attempt on a tropicbird egg, adding to our knowledge of the ecology of these snakes. She has also documented growth of some of the individuals released on Gunner's Quoin in 2012, as well as thriving Telfair's Skink populations, on which the snakes feed (sometimes successfully, sometimes not). Data analysis is on-going, e.g. new update here.

ACKNOWLEDGMENTS

Thanks to photographers Richard Gibson, Gregory Guida, Mike Pingleton, Drymarchon32, and Jim.

REFERENCES

Bauer A, Günther R, 2004. On a newly identified specimen of the extinct bolyeriid snake Bolyeria multocarinata. Herpetozoa 17:179-181.

Cundall D, Irish FJ, 1989. The function of the intramaxillary joint in the Round Island boa, Casarea dussumieri. Journal of Zoology 217:569-598.

Frazzetta T, 1971. Notes upon the jaw musculature of the Bolyerine snake, Casarea dussumieri. Journal of  Herpetology 5:61-63.

Hallermann J, Glaw F, 2005. Evidence for oviparity in the extinct bolyeriid snake Bolyeria multocarinata (Boie, 1827). Herpetozoa 19:82-85.

Korsós Z, Trócsányi B, 2002. Herpetofauna of Round Island, Mauritius. Biota 3:77-84.

Korsós Z, Trócsányi B, 2006. The enigmatic Round Island burrowing boa (Bolyeria multocarinata): survival in the wild remains unconfirmed. African Herp News 40:2-7.

Maisano JA, Rieppel O, 2007. The skull of the Round Island boa, Casarea dussumieri Schlegel, based on high-resolution X-ray computed tomography. Journal of Morphology 268:371-384.

McAlpine DF, 1983. Correlated physiological color change and activity patterns in an Indian Ocean Boa (Casarea dussumeri). Journal of Herpetology 17:198-201.

Life is Short, but Snakes are Long by Andrew M. Durso is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.