Tuesday, 13 December 2011

Vanuatu Caddisflies

A recently published paper by Kjell Johanson revises the caddisfly fauna of Vanuatu, descibing 12 new species and providing a key to the species currently known from the archipelago. It is an important contribution to the knowledge of the caddisfly fauna of the region, as most of the previous work done on the fauna of the region is several decades old.

A couple of things stood out to me in this paper. The first is that Orthotricha has not been recorded from any other oceanic Pacific islands. These are small (2-3 mm wing length) creatures, and it is likely that they just haven't been collected elsewhere in the Pacific. The second was their discovery that a female of Triplectides australis had a large number of larvae inside her abdomen. While I was hitherto unaware that ovoviviparity occurred in caddisflies, it turns out that this has been known since 1890, the first instance of it being confirmed by Prof. Wood-Mason in the following manner:
I threw the insect alive into a liqueur-glass of whiskey that happened to be ready at hand.

Adult caddisflies tend to be overlooked by the general public, usually being confused as small, fairly dull-looking moths. Their larvae are aquatic where they form an important part of the macro-invertebrate fauna of streams, and can be useful as indicators of water quality and stream health. Unfortunately, very little biological information is recorded in the paper, and larvae are not considered. In part this is due to Malaise and light traps providing the bulk of the material that was considered in the revision. Discovering and describing larvae and their habitats is a natural application of the taxonomic effort of this paper.

References

Johanson KA, Wells A, Malm T, Espeland M. 2011. The Trichoptera of Vanuatu. Deutsche Entomologische Zeitschrift 58(2): 279-320.

Wood-Mason J. 1890. On a viviparous caddis fly. Annals and Magazine of Natural History 6th series, 6: 139-141.

3 comments:

ZL "Kai" Burington said...

Wow, great post. I had no idea that /any/ caddisflies were ovoviviparous. KA Johanson, Hans Malicky and others are a definite force in Southeast Asia and the South Pacific, in terms of describing new species. At the same time it feels like one of those old grab and run taxonomic jobs, where these teams are island hopping, snatching as many species as possible, and then moving on to the next. This is much the old style, where theres no real attempt to investigate the species beyond their primary descriptions. It may just be efficiency, or it could be mihi itch. Either way, I don't find it to be the right way of doing things. With such a small number of species, there should be a real ease in terms of matching larvae with adults.

Unknown said...
This comment has been removed by the author.
Unknown said...

Females of the New Zealand leptocerid, Triplectides cephalotes are also live-bearers. I have a photo of first instar larvae visible through the female abdominal wall, but I don't think I can add it to this post.