New Zealand Bat Fly
The New Zealand batfly, Mystacinobia zelandica, is a small, wingless insect which lives in a symbiotic relationship with the New Zealand Lesser Short-tailed Bat. It is a member of the true flies that belong to the order Diptera but is so unusual that it is placed in its own genus, Mystacinobia, and family, Mystacinobiidae - this monotypic family is endemic to New Zealand.
New Zealand batflies are 3 mm long, wingless in both sexes, blind, and have long, bristly, spider-like legs which end in specially adapted claws which are thought to help them "swim" through bat fur. Males are larger than females and look quite different; one Japanese expert when sent some of the first specimens collected for scientific study suggested that they were different species.
Mystacinobia was discovered in 1958 and the first specimen was catalogued for analysis by a zoologist named P.D. Dwyer in 1962 after it dropped out of the fur of a Short-tailed Bat he was looking after. In 1973 a 56 metre high kauri tree named Kopi (thought to be the third largest in the country after Tane Mahuta and Te Matua Ngahere) in the Omahuta Kauri Sanctuary in Northland containing a large colony of short tailed bats collapsed. When inspected the following day a dead bat with three batflies on it was found by a NZ forest service officer who sent the insects to Auckland to be studied. The opportunity to study live batflies and learn about their behaviour and ecology was lost when the bats deserted their felled roost before a team of scientists from DSIR was assembled to investigate it. Two years later on 14 March 1975 however, the kauri tree which the bats that had previously occupied Kopi had moved into was blown over as Cyclone Allison swept through Northland. This time entomologists were able to collect a large number of batflies for anatomical studies and to keep in captivity so that their behaviour could be properly studied
Almost everything about this fly is unusual. They are not dependent on the blood of the bats it lives with, instead it feeds on their faeces; guano. Like its host it lives in colonies and the females lay their eggs together to form a nursery of eggs and larvae. The adult females will groom the larvae in the nurseries as well as each other and their other colony mates. There also seems to be the beginning of a caste system as some of the males live past their normal reproductive age and act as colony guards. These elderly males produce a high frequency buzz that seems to keep the bats from flying too close to the fly colony.
Taxonomy and naming
Molecular analysis suggests that it evolved from a blowfly ancestor. the ancestors of the host species (Icarops, a miocene bat which lived 20MYA) also lived in Australia but it is not known whether the New Zealand batfly evolved there or in New Zealand as it could have been transported across the Tasman Sea with its host
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- Holloway, B. A. (1976). "A new bat-fly family from New Zealand (Diptera: Mystacinobiidae)". New Zealand journal Zoology (The Royal Society of New Zealand) 3: 279–301.
- Ballance A. Morris R.(2008).Rare Wildlife of New Zealand, page 39. Random House
- Gibbs G.(2008). Ghosts of Gondwana, page 16. Craig Potton publishing
- Meads M.(1990). Forgotten Fauna, page 92. DSIR publishing
- Hunt R. Morris. R. (2006) Batfly! New Zealand Geographic # 81
- Ross Piper (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.