A stocky, medium-sized (up to 2 m long) and poorly known elapid with notably small eyes, Micropechis ikaheka - the Small-eyed or Ikaheka snake - is the only recognised member of its genus*. It's unique to New Guinea and some of the surrounding islands [adjacent image from Warrell et al. (1996)].
'Ikaheka' means 'land eel' in the local dialect and refers to the fact that it is sometimes associated with streams and other damp habitats. Micropechis is secretive, nocturnal or crepuscular and hunts for reptiles, frogs and mammals in cluttered rainforest and wetland habitats. It is regarded as dangerous to humans and several fatalities are on record; most recorded bites involved local swelling, neurotoxicity, myalgia, systemic bleeding and the passing of dark urine (Warrell et al. 1996). The common name Small-eyed snake is also used for Australian small-eyed snake Rhinoplocephalus nigrescens. It has been asserted that the generic name must be pronounced 'microp-echis', and not 'micro-pechis' (Warrell et al. 1996) [image below from here].
* Though note that Loveridgelaps elapoides was regarded as a species of Micropechis until McDowell (1970) gave it its own genus.
Studies on the relationships of elapids initially included Micropechis among the 'palatine dragger' assemblage that also included Toxicocalamus, Aspidomorphus, Loveridgelaps, Salomonelaps and Ogmodon (McDowell 1970). In his molecular studies of elapids, Keogh (1998) found that Micropechis was most closely related to the highly distinctive whipsnake genus Demansia. More recently, Micropechis has been recovered as one of the most basal members of the hydrophiine elapid clade Oyxuraninae, as have most other members of McDowell's Melanesian 'palatine dragger' assemblage (Sanders et al. 2008). The fact that basal hydrophiines are mostly or entirely Melanesian animals of wet tropical habitats supports the view that Australia was colonised from the north by animals using mesic habitats.
Molecular clock estimates indicate that the entire hydrophiine radiation is very young, with one of the most basal divergences (between Laticauda sea kraits and all other hydrophiines) happening about 12 million years ago. The 100 or so oviparous and viviparous terrestrial hydrophiines and about 60 species of sea snake all emerged very rapidly between about 10 and 6 million years ago (Sanders et al. 2008). This is a very young, explosively successful radiation.
For previous Tet Zoo posts on elapids and other snakes see...
- Scolecophidians: seriously strange serpents
- Side-stabbing stiletto snakes
- Terrestrial elapids, take 2
- Why do some snakes have horns?
- Close encounters with the Father of Death
- Not two, not three, but FOUR anacondas
- The tiniest snakes
- Snake 195 mm long eats centipede 140 mm long. Centipede too big. Snake dies.
Refs - -
Keogh, J. S. 1998. Molecular phylogeny of elapid snakes and a consideration of their biogeographic history. Biological Journal of the Linnean Society 63, 177-203.
McDowell, S. B. 1970. On the status and relationships of the Solomon Island elapid snakes. Journal of Zoology 161, 145-190.
Sanders, K. L., Lee, M. S. Y., Foster, R. & Keogh, J. S. 2008. Molecular phylogeny and divergence dates for Australasian elapids and sea snakes (hydrophiinae): evidence from seven genes for rapid evolutionary radiations. Journal of Evolutionary Biology 21, 682-695.
Warrell, D. A., Hudson, B. J., Lalloo, D. G., Trevett, A. J., Whitehead, P., Bamler, P. R., Mamy Ranaivoson, Wiyono, A., Richie, T. L., Fryauff, D. J., O'Shea, M. T., Richards, A. M. & Theakston, R. D. G. 1996. The emerging syndrome of envenoming by the New Guinea small-eyed snake Micropechis ikaheka. Quarterly Journal of Medicine 89, 523-530.
Sea Snakes evolved a very potent neuro-toxin venom so that they could stun fishes rapidly and then easily manipulate them into their mouths without dropping them to the ocean floor.Sea snakes were once grouped with HYDROPHIIDAE,but are part of the family Elapidae.All except the Sea Krait are vivparous and give birth at sea. There are 15 genera and 70 species distributed in Papua New Guniea, Australia, and tropical Pacific and Indian Oceans.
The habits of Snakes can be seen in their eyes.small degenerate eyes suggest burrowers, vertical elliptical pupils are nocturnal species. large round eyes are active diurnal predators that chase down their prey
Sea snakes were covered a couple of times at Tet Zoo ver 1, but I have yet to update this stuff and recycle it here at ver 2...
Plus there's this very brief look at Aipysurus-group sea snakes.
On Chad Arments Blog Herper.com he noted an Albino small eyed Snake, reported in the Brisbane Times article of Nov 18 2009 The Australian species of course.
Perhaps its time to move on the Big eyed Snake Mimophis Mahfalensis of Madagascar.
The 100 or so oviparous and viviparous terrestrial hydrophiines and about 60 species of sea snake all emerged very rapidly between about 10 and 6 million years ago (Sanders et al. 2008). This is a very young, explosively successful radiation.
The evolutionary success of sea snakes (if success is measured by the number of living species) is particularly interesting in comparison to that of the other major clade of extant marine "reptiles", the sea turtles. Their evolutionary lineage is older and they are geographically more widespread (they are not restricted to the tropical Indo-Pacific like the sea snakes are) - and yet there's only a handful of sea turtle species. Is this just some Holocene anomaly? Have sea turtles ever been significantly more diverse and speciose at any time during the Cenozoic?
Darren wanted to check these papers but couldn't get hold of them in time for this (urgent?) post:
Scanlon, J.D. & Lee, M.S.Y. 2004. Phylogeny of Australasian venomous snakes (Colubroidea, Elapidae, Hydrophiinae) based on phenotypic and molecular evidence. Zool. Scr. 33: 335â366.
Scanlon, J.D., Lee, M.S.Y. & Archer, M. 2003. Mid-tertiary elapid snakes (Squamata, Colubroidea) from Riversleigh, northern Australia: early steps in a continent-wide adaptive
radiation. Geobios 36: 573â601.
Pdf's are on the page linked through my name. I tend to think that Sanders et al's dates are just a bit too young, but not by much; we've got a few Miocene fossils (~10-20 Ma) but none are referable to extant genera, which contrasts with what we see for colubroids (including elapids) in Europe and North America, or other groups (particularly pythons) in Australia. Turtles must be about two orders of magnitude slower at speciating.