One would have imagined that the taxonomy, though not the phylogeny, of snakes, which loom large in human imagination and lurk in the myths of continental tribes, is a tale with a short end. Students of fresh resolve, armed with tools and techniques offering greater resolution of discrepancies between and within populations, however, have teased out morphological signs and molecular signals that support the splitting of once singular taxa. The wide-ranging, euryhaline bockadams, it seems, must now be regarded as a complex of five serpents: Cerberus rynchops of India and the Bay of Bengal; Cerberus schneiderii, which hunts in Sundaland's coasts; C. microlepis, endemic to a freshwater lake in Luzon; the Micronesian C. dunsoni; and C. australis from the Australopapuan region.
A similar fate has befallen the snakes commonly known as Wagler's or temple pit vipers, which occur throughout much of Southeast Asia from Southern Thailand and South Vietnam to Sumatra, Borneo, Sulawesi and the Philippines, though curiously not in Java. In the Malay Peninsula, Tropidolaemus wagleri was known as ular kapak, for its broad, heart-shaped head recalls the biting flank of a hatchet. The natives of Sumatra call it puchuk, referring perhaps to the shoot-like crown and light green shades of juveniles and adult males, which also have red and white streaks across their eyes. Females, which can reach a metre in length, are dark worms with green speckles and yellow crossbars. Clinging to low branches with the aid of a prehensile tail, the snakes await arboreal prey such as lizards, birds, rats and tree frogs, detecting warm-blooded victims with thermoreceptive pits between eye and nostril and sealing their fate with a haemotoxic strike. In humans, the bite results in painful swelling, and this relative mildness compared to the fangs of kraits and cobras may have contributed to the viper's uneasy truce with some inhabitants of the region, who are said to drape the sluggish animals on trees near their dwellings for luck. Echoing these reports, the gardeners of a colonial bungalow near the summit of Penang Hill readily collect specimens they find around the premises and employ the reptiles as subtle accompaniments to the meals of unruffled guests.
A sizeable colony of these vipers can also be found in the grounds of a Chinese temple in Bayan Lepas, near the southeastern coast of Penang. Located some distance from the streets of Georgetown, Ban Kah Lan overlooks a highway between the airport and the city, and faces a trunk road lined by food hawkers and trinket stalls. But a century ago, the temple must have sat amid foothills and forested vales abounding with island life, some of which invaded fresh structures for shelter and food. A fellow shrine on the slopes of Ayer Itam houses a thin cloud of bats, while the Ser Miao offers dubious sanctuary to the survivors of a now industrialised zone, who spend their days on fruit trees in a walled grove, awaiting perhaps their turn before the altar where incense, or perhaps the incessant tributes of the faithful, lulls their senses and leaves them none the wiser than their untrammeled kin.
A minor mystery of zoogeography lurks in the vipers' cold glares and disguised gapes. The genus, which differs from other Asian crotalines by the absence of a nasal pore, the highly keeled scales covering the upper surface of the head and snout, and the distinctive colours of young animals, exists as far west as India, where two juveniles of T. huttoni were first, and last, recorded in 1949. At least two species once thought to be 'green' and 'red' forms of T. wagleri, the strikingly marked T. laticinctus and plainer T. subannulatus, share the island of Sulawesi. The latter is a label of convenience, for it denotes a complex found in the isles east of Bangka and much of the Philippines, where the species exists in sympatry on Mindanao with T. philippensis. An individual in mid-moult, with white spots on green and a white and red postocular stripe, encountered by a guide near Tangkoko Nature Reserve during a search for smaller beasts, was probably from a male from this group, and despite the handicap, exuded no less menace from his coils and half-blinded crown.
Cophias, Trimeresurus, Coluber, Trimeserus, Lachesis, Trigonocephalus – nomenclatural confusion has plagued Wagler's pit viper since its posthumous description in 1827. In Singapore, the steady retreat of mature forests and their replacement by clean, green parks have hounded the snakes to unkempt refuges where they suffer little persecution and endure only the enmity of long-tailed primates. A few brave the fringes of jungle trails, the better perhaps to intercept small creatures disorientated by busy clearings, and probably remain undetected for days until they snare a meal or try their luck on a fresh perch. Broken canopies and ring roads prevent the snakes from invading urban gardens, and wanderers to the edge of existence have no recourse but to work their way back to wooded hills or wind up the victims of blind progress. Such was the choice confronting a young female bearing the patterns, but not the full darkness, of adulthood, spotted on a branch right above a sidewalk, who saw no reason to leave her post until she was persuaded by a gentle stick that lifted her from public view and into the seclusion of a dense slope, where she scaled a log and stared down, alert and aggrieved, the heavy-handed affront to her mildness and mute majesty.
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