1998 Madagascar Expedition

Background
Michael E. Irwin is Professor, Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana. He studies predaceous flies belonging to the stiletto fly family (Diptera: Asiloidea: Therevidae). His laboratory is engaged in a long term study to elucidate their phylogeny, biogeography, and biology. The project is supported by a National Science Foundation, Partnership for Enhancing Expertise in Taxonomy (PEET) grant and by funds generously provided by the Schlinger Foundation.

Evert I. Schlinger is Professor Emeritus, Department of Entomological Sciences, University of California, Berkeley. He studies spider parasitoids of the fly family Acroceridae (Diptera). His laboratory, located in Santa Ynez, California, is currently associated with the Department of Biology, University of California, Santa Barbara. He is engaged in a long term study to elucidate the phylogeny, biogeography, and biology of acrocerids.

Both therevids and acrocerids are found throughout the world. Therevids have their centers of radiation in warm, dry climates, while acrocerids are more closely associated with temperate to tropical climates. Larvae of therevids are voracious predators of other insect larvae living in sandy substrates and litter zones. Acrocerid larvae are specific parasitoids on many groups of spiders. Adult acrocerids are specific pollinators of plant species. The evolution of these groups has been greatly influenced by the breakup of the continents, especially Gondwanaland. Both scientists are aware of the importance of Madagascar in resolving the evolution and biogeography of their respective groups. Because therevids are secretive as adults and fossorial as immatures, they are rarely collected. Likewise, acrocerids are extremely rare and fast flying, and thus rarely collected. For these reasons, the therevid and acrocerid flies of Madagascar remain largely undiscovered but potentially very important for elucidating the phylogeny of the groups.

One of the most important components of their respective projects is to collect therevids and acrocerids in critical, undersampled areas of the world. Over the past 35 years, they headed major collecting expeditons to gather both groups in the following major land masses: Western North America incuding Mexico, Central America, Chile, Argentina, Australia, New Zealand, Japan, New Caledonia, and Southern Africa. Madagascar is a land mass that is potentially rich in species and ancient higher taxa, but very little is known from there. The short trip to Madagascar in April 1998 added a new dimension to the exploration phase of the research.

We were part of the California Academy of Sciences Expedition to Ranomafana National Park. However, our collections were more extensive, covering a number of localities both inside and outside of the park. Collecting techiniques included hand netting and using Malaise traps to capture adults and sieving leaf litter and sand to collect therevid larvae, and rearing spiders to obtain adult acrocerids.

Therevidae: Prior to our expedition, Fred Keiser, Switzerland, collected a number of therevids in Madagascar; furthermore, two major Diptera expeditions occurred during the mid 20th Century, both headed by Dr. Brian Stuckenberg of the Natal Museum, Pietermaritzburg, South Africa. One of these was in December of 1955, the other in February of 1957. In two noteworthy publications, Dr. Leif Lyneborg (Lyneborg 1976, 1989) reviewed the known species and described a number of additional species in Madagascar, almost exclusively from material obtained through the sources noted above. All presently recognized species in Madagascar are known from no where else in the world. There are currently three genera recorded in Madagascar: the endemic genus Stenopomyia Lyneborg with 13 described species, the widespread Afrotropical and Oriental genus Irwiniella Lyneborg with three described Madagascar species, and the Afrotropical genus Rueppellia with two species described from Madagascar. These taxa are listed in Appendix I.

Acroceridae: Before our expedition to Madagascar there were only 9 species in 3 genera of Acroceridae known from Madagascar, all in a single subfamily, Philopotinae. For those nine species only "12" specimens were known, and there had never been any spider host specimens recorded from Madagascar. These taxa are listed in Appendix II.

Results
Therevidae: Three specimens of Stenopomyia were collected in Malaise traps within the Ranomafana National Park, all females. They represent two distinct species, S. fumipennis Lyneborg and an apparently undescribed species. Two females and one male of Irwiniella velutina (Krober) were collected along the coastal beach system to the east of Ranomafana. And a few specimens of two species within the genus Rueppellia, R. keiseri Lyneborg, represented by 1 male and two females, and R. multisetosa Lyneborg, represented by 3 males and 2 females, were collected from a dune system near Ifati along the southwestern coast of Madagascar.

Acroceridae: Following our expedition last April, and through our collecting, rearing the flies from their spider hosts (as carried out by our colleagues in the California Academy of Sciences), studying the specimens present in the Scientific Institute collection in Tananarive and the Natural History Museum in Ranamofana National Park, and the several undescribed species and genera in the collection of Professor Schlinger, we now find that we have 9 new species and 2 new autochthonous genera that need to be described. Further, one of these genera, Ogcodes, represents the first record of the subfamily Acrocerinae, and 3 of the new species are of this genus. Further, 4 of the 6 genera and all 18 specimens are most likely autochthonous taxa. While we have doubled the number of specimens present in Madagascar, we have also doubled the number of species known, i.e. 25 specimens represented by 18 separate species!

The rearing of these flies by Dr. Griswold and Darrel Ubick, et. al. in the Ranamofana Scientific Laboratory gave us the following primary records of spider parasitoids in Madagascar:
1.) Ogcodes n.sp.(female), reared from an immature clubinoid or miturgid spider.
2.) Thylllis n.sp (male), reared from Ambohina sublima, a Phyxelidid spider, det. by C.E. Griswold.
3.) Another specimen from the same host spider, died in the pupal stage, and is presumed to be the same Thyllis n.sp. above.
The list of acrocerid flies now known from Madagascar are listed in Appendix II.

Other material: The several malaise traps that we set up in Ranomafana and elsewhere captured insects other than Therevidae and Acroceridae. All of that material, several thousand specimens, was brought back to the University of Illinois, packaged, and sent to the California Academy of Sciences for curation and deposition within the general guidelines set down for this project. This material was shipped to CAS as six small boxes of pinned material, eight boxes of layered material, and three half-liter neoprine containers with whirl-paks containing alcohol material. One malaise trap was left at the cook house at Ranomafana. Material from it was to be removed to whirl-paks weekly. We wired some funds to MICET to purchase additional alcohol for this purpose. As of this writing, the material has not yet been sent to Illinois for sorting and distribution. When it does, the Therevidae and Acroceridae will be removed for study by us, and the bulk of the material will be sent to the Calfiornia Academy of Sciences to be handled in the maner suggested above. We also left a few small malaise traps with Dr. Steve Goodman of the Field Museum of Natural History, Chicago, so that he could collect flies during his survey work in Madagascar. Material from those traps, when we receive it, will be sorted, the Therevidae and Acroceridae removed for study, and the remainder sent to the Field Museum for curation.

References

• BRUNETTI, E. 1926. New and little known Cyrtidae. Ann. Mag. Nat. Hist. 18: 561-606.
  
• LYNEBORG, L. 1976. A revision of the Therevine stiletto-flies (Diptera: Therevidae) of the Ethiopian Region. Bull. British Mus. (Nat. Hist.). Entomology 33 (3): 191-346.
  
• LYNEBORG, L. 1980. Therevidae, pp. 314-320, in R.W. Crosskey, ed., A Catalogue of the Diptera of the Afrotropical Region. Pub. Brit. Mus. Nat. Hist. 1437 pp. , London.
  
• LYNEBORG, L. 1989. The first records of Phycini from Madagascar (Diptera: Therevidae: Phycinae). Ann. Natal Mus. 30: 159-163.
  
• PAULIAN, R. 1961. La Zoogeographie de Madagascar et de les Voisines. Fauna de Madagascar. XIII, 486p. 122 fig.
  
• SCHLINGER, E. I. 1960a. A revision of the genus Ogcodes Latreille with particular reference to species of the western hemisphere (Diptera: Acroceridae). Proc.U.S. Nat. Mus. Vol. 111, No. 3(3429): 227-336, figs. 1-112.
  
• SCHLINGER, E. I. 1960b. A review of the South African Acroceridae (Diptera). Ann. Natal. Mus. 14(3): 459-504.
  
• SCHLINGER, E. I. 1961. A revision of the Acroceridae of Madagascar. Mem. L'Inst. Scient. Madagascar, Series E, 12: 257-267, figs. 1-8.
  
• SCHLINGER, E. I. 1980. Acroceridae, pp. 377-380, in R.W. Crosskey, ed., A Catalogue of the Diptera of the Afrotropical Region. Pub. Brit. Mus. Nat. Hist. 1437 pp. , London.
  
• SÉGUY, E. 1962. Note sur trois Thyllis de Madagascar. Bull. Mus. Nat. Hist., Paris, (2) 33 (1961): 589-593.

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