- Badisis ambulans
name = "Badisis ambulans"
status = NE
image_width = 240px
ordo = Diptera
genus = "Badisis"
genus_authority = McAlpine, 1990
species = "B. ambulans"
binomial = "Badisis ambulans"
binomial_authority = McAlpine, 1990
range_map_width = 240px
range_map_caption = Global range of
Albany Pitcher Plant, maximum range of "Badisis ambulans" (see text)
"Badisis" is a
stilt-legged fly genuswith only one known species, "Badisis ambulans". This is a wingless, haltere-less flywith an ant-like appearance. It is only found in the Southwest Australian bioregionof Western Australia. Dependent on the rare Albany Pitcher Plant("Cephalotus follicularis") for its development, this fly is also a rare species.McAlpine (1998)]
Despite its many
apomorphic features, the details of its morphology suggest a close relationship to the diverse genus " Metopochetus", which is also in the tribe Metopochetini. The fossilstilt-legged fly ""Electrobata" tertiaria" from Baltic amberof the Paleogenealso shows some similarities; it may be a very basal member of the Metopochetini, close to the divergence between these and the Eurybatini.
Apart from its lack of wings and
halteres, "B. ambulans" has a less unusual habitusthan other members of the Micropezidae. Its body is stockier, with a petiolate abdomen (like in ants and other Apocrita), its middle and hind legs are less elongated, and its forelegs are less shortened than in its relatives. At a casual glance, it is easier to confuse with an ant than with other micropezid flies. The two sexes are almost identical; they can be told apart essentially just by microscopicstudy of the tip of the abdomen. The larva is adapted to its strange habitat, the pitchers of the Albany Pitcher Plant. In third- instarlarvae (and likely in others too), the slits of the posterior spiracleare entirely closed. Head
compound eyes are as large like in " Metopochetus", an unusual feature among wingless Diptera, many of which lack them altogether. The third antennal segment of "Badisis" is elongate-oval. There are usually three bristles ( setae) on each side of the "forehead". Rare among stilt-legged flies but also found in "Metopochetus", there is a knob below the postvertical bristles. The prelabrumis large but not markedly projected forward at the lower margin. Thorax
The scutellum is distinctly visible but rather small. Like in most other
Eurybatinae, there is no groove connecting the mesoscutal transversesutures across the centerline of the mesothorax. The metathoraxhas a dorsal scleriteshaped like a saddle.
The petiole is formed by the first two segments of the abdomen, the first of which has a slight bulge on the
tergite. In the male the postabdomenis highly characteristic, the sterniteof the 5th postabdominal segment is shallow divided into 2 lobes, each of which bears two or three stout bristles at the tip; the entire structure is very similar to that of " "Electrobata" tertiaria". The 6th sternite is triradiate like in "Metopochetus", but like in Eurybatininot compressed laterally and with a trough-like channel in the middle. The subepandrialsclerite of male "Badisis" has a very small prominence with a minute setula at its tip. The aedeaguswith its moderately long two-segmented distiphallusresembles that of "Metopochetus" subgenus"Crus". On the other hand, the ejaculatory scleriteof "Badisis" is unlike that of any known "Metopochetus", with a rod-like apodemeexpanded at the tip like a mushroom-head. Females show the conventional postabdominal structure of stilt-legged flies.
The coxa of the forelegs has a tooth-like lobe on the lower forward end. Such a feature is apparently only found in "Badisis" and "Metopochetus". The tibiae of mid- and hindlegs bear fine hairs (setulae) and numerous but scattered thicker bristles.
Ecology and status
Coextinction"Males are far more often seen than females; the latter were only described 8 years after the former. As far as is known, "B. ambulans" inhabits sclerophyll forest, where the males are occasionally encountered on flowers of the Myrtaceae shrub" Astartea fascicularis". If they feel threatened, they will try to escape by hopping and letting themselves drop down to the ground where they can hide.
The larvae have to date only been found in the pitchers of the
Albany Pitcher Plant("Cephalotus follicularis"). This carnivorous planthas a limited range in southwestern Western Australia, effectively restricting the fly's range also. Most significantly, the plant is found in the Warren, Jarrah Forestand Esperance Plainsbiogeographic regions.
conservation statusof "B. ambulans" has not been evaluated yet. The Albany Pitcher Plant is classified as a Vulnerable speciesby the IUCN. Its numbers are declining, mainly due to habitat destruction and collecting for horticulture(though there is by now a good supply of culture-grown plants, which are also far easier to maintain than those collected from the wild). The Albany Pitcher Plant prefers somewhat moister habitatthan the fairly aridlocations where adult "B. ambulans" have been collected. Thus, either that the adult flies are more mobile than their winglessness suggests, able to walk for prolonged distances, and consequently more resilient to local extinctions of the Albany Pitcher Plant. On the other hand, the flies might be restricted to the dry spectrum of the plant's habitat, making them more localized and consequently even more threatened than the plant is. [Conran "et al." (2000), McAlpine (1998)]
*|year=2000|id=39635|title=Cephalotus follicularis|downloaded=11 May 2006
* (1998): Review of the Australian stilt flies (Diptera: Micropezidae) with a phylogenetic analysis of the family. "Invertebrate Taxonomy" 12(1): 55-134. DOI|10.1071/IT96018 (HTML abstract)
* (1990): A new apterous micropezid fly (Diptera: Schizophora) from Western Australia. "Systematic Entomology" 15:81-86.
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