Thursday, 13 September 2007

The Thursday gastropod: Rhynchotrochus macgillivrayi

Yes, it's another camaenid but we've got plenty to spare. And I'm sure you'll agree this is a rather splendid one*. Rhynchotrochus macgillivrayi (Forbes 1851) is a tree snail from the Wet Tropics of Far North Queensland. It is the only known representative of the genus in Australia. All other species — and there are many — occur in New Guinea and neighbouring islands.


Dunk Island


Naturalist John MacGillivray collected specimens from trees in the Frankland Islands, North Queensland, during the voyage of the HMS Rattlesnake. Edward Forbes named the species in his honour.
Of all Australian Helices, this is perhaps the most curious. Its outline and aspect are singularly like those of a Trochus of the Ziziphinus group. The colour is also very singular, being a yellowish flesh hue deepening on the base to a rich brownish-yellow, and speckled irregularly with minute black dots which are areolated with white, the white ring being largest on the side towards the mouth ... The outer lip of the aperture seems as if it had been dented in two places.

The dent is known as the papuinid notch (after the camaenid subfamily Papuininae to which the genus belongs).


Distribution of R.macgillivrayi


William Clench and Ruth Turner (1966) produced a monograph of Rhynchotrochus but not much has been done on the group since then. It's hardly surprising.
The genus Rhynchotrochus is the most complicated among the elements in the Papuininae ... Our present understanding of the species and forms composing the genus are certainly no more than tentative and will be subject to considerable modification when more material is at hand for study. The most serious handicaps at present are the lack of localized specimens, alcoholic material, and the complete inadequacy of many of the original descriptions.

More than forty years later, the situation has hardly changed.

_____

* If slightly over-exposed. Sorry about that, chief.


References
Clench, WJ & Turner, RD. (1966). Monograph of the genus Rhynchotrochus (Papuininae: Camaenidae). Journal of the Malacological Society of Australia 1(9): 59–95.

Forbes, E. (1851) On the Mollusca collected by Mr. MacGillivray during the voyage of the Rattlesnake in MacGillivray, J. Narrative Of The Voyage Of H.M.S. Rattlesnake, Commanded By The Late Captain Owen Stanley, R.N., F.R.S. Etc. During The Years 1846-1850. Vol. 2. London: T & W Boone.

2 comments:

sarala said...

Love the 1851 reference. We believe science is changing so fast but some observations are as valid now as 150 plus years ago.
That is quite a snail.

Snail said...

It's a little cutie. I'm putting it on my list of things to work on when I head back to the Deep North.