APOCEPHALUS

Systematics of ant-decapitating flies, genus Apocephalus

(Insecta: Diptera: Phoridae) 



Principle Investigator: Dr. Brian V. Brown  

Natural History Museum of Los Angeles County (LACM)

ABSTRACT.

This is a five-year project funded by NSF grant DEB-9407190. Its goals are to revise the following five groups of ant- decapitating flies within the genus Apocephalus:

1) subgenus Mesophora, parasites of cantharoid beetles, wasps and bees.

2) A. attophilus-group, parasites of fungus-gardening ants.

3) A. miricauda-group, parasites of ponerine ants.

4) A. mucronatus-group, parasites of carpenter ants (Camponotus).

5) A. pergandei-group, parasites of carpenter ants (Camponotus).

There are 110 described species of this parasitic genus, most of which are known from small collections from Atlantic coastal Brazil: therefore a considerable amount of new collecting is necessary. Mass sampling using Malaise traps will be augmented with on-site hand collecting and rearing to establish host- parasite relationships and to collect immature stages of the flies. Hypotheses of relationships within the genus will be reconstructed using structural characters and the methods of phylogenetic systematics. These hypotheses, in the form of cladograms, will allow the reconstruction of host preference, biogeography and behavior of these flies. An unusually large number of specimens will be processed during this study, but automated data storage (using DELTA), interim taxonomy procedures and the assistance of a full-time artist/ technician will allow fulfillment of all research goals. The genus Apocephalus is expected to total about 400 species, necessitating the description of about 300 new species, or 30 new species per year over the estimated 9 years needed to revise the entire genus. This productivity is higher than that of most entomological systematists, but is attainable given the collecting network already established and the requested technical help. This revision will be a major contribution to the study of New World biodiversity, providing information not only on a large group of little-known flies, but also on the range of interactions with their hosts.

PROGRESS

Artist/Technician. I have hired Mr. Jesse Cantley MFA to fill this position. For an example of one of his drawings, click here.

Project 1. Revision of Mesophora. I had already partially revised this group in 1993, and a great deal of background information existed for its further study. I constructed a preliminary reconstructed phylogeny of relationships, based on synapomorphic character states, but this initial analysis was hampered by a lack of material of one sex or another. Since this revision, I have gathered a large amount of new material, including several new species, as well as the previously unknown males and females for various species. Furthermore, it was evident that the majority of species probably are parasites of fireflies, and that associating hosts with parasites and rearing larvae would be relatively easy.

In March of 1995, Jesse Cantley and I travelled to Costa Rica to collect these flies. For a general account of this trip, see the article in Phorid Newsletter #3. Furthermore, I travelled to Costa Rica in August of 1995, and reared an additional new species from stingless bees at Las Alturas field station. See Brown, in press-c, below.

The major results of this work are summarized in Brown, 1996a. The abstract of this paper is as follows:

Twelve new species of Apocephalus, subgenus Mesophora are described and named; an additional 6 unassociated males and females are described but not named. The twelve new species are A. apivorus, atavus, emphysemus, lemniscus, lizanoi, megalops, niveus from Costa Rica, and A. crassus, echinatus, pilatus, prolixus and secundus from the Dominican Republic. A.leptotarsus Brown is synonymized with A. antennatus Malloch new synonymy. The previously unknown male of A. absentis Brown is described, as are the previously unrecognized females of A. adustus and A. curtus. A new key to species of the Neotropical Region is given. The relatively most primitive species, A. apivorus and adustus are parasitoids of stingless bees, whereas A. tritarsus is a parasitoid of lampyrid beetles, like most other Mesophora. The host shift within the subgenus Mesophora from ants to lampyrid beetles appears to have been via parasitism of stingless bees.

Parasitism of stingless bees was a newly discovered phenomenon in this genus, and warranted separate discussion in a paper in the journal Biotropica (see Publications, below).

Project 2. Revision of the Apocephalus attophilus-group, parasitoids of fungus gardening ants. This research is complete, and the results will be published shortly, probably in late 1997. I identified 58 species, of which 44 were undescribed.

Fieldwork for year 2 consisted of a month-long trip to Ecuador to collect specimens and study host-parasitoid interactions. We joined LACM Field Associate Peter Hibbs, who had been in Ecuador since January, and whose trip was supported largely by a special grant from the LACM Taylor Fund. Peter operated Malaise traps at several sites from January- July, vastly increasing the number of specimens available for study. Additionally, he arranged collecting and export permits, and served as a guide and field assistant for me at no additional cost to NSF.

During our visit we studied phorids at three sites: Maquipucuna Biological Reserve, Bilsa Biological Station and Yasuni Scientific Research Station. A full account of this highly successful trip was given in the Phorid Newsletter (Fall 1996).

Project 3. Revision of the A. miricauda-group. Work on this project is proceeding, but the group is much larger than previously imagined. Most of these flies are parasitoids of injured ponerine ants, but we have discovered hosts of some species in other ant subfamilies. An important aid to this research was the award of an NSF Research Experience for Undergraduates grant from NSF, which was partially matched by the LACM. I hired two students, Mr. Giar-Ann Kung and Ms. Jill Paldi, to assist in lab and field research and to conduct independent research on their own projects. Field work for year three consisted of a short but highly successful trip to Costa Rica, in conjunction with the 1997 Association for Tropical Biology meeting, where I presented a paper about this work. Also, I participated in the Arthropods of La Selva workshop on Malaise trap samples, an NSF-funded project that continues to provide important material for my work. After the meetings, Jill Paldi and I conducted research at the Cacao and Pitilla Biological Stations, both in Guanacaste Province, northern Costa Rica. We found a number of new host- parasitoid associations, and made observations on the life history of several A. miricauda-group species.

Processing of phorid flies continues by the preparator. We have cataloged a total of 28,567 phorid flies in the database, of which 9,791 are Apocephalus. The LACM collection of Apocephalus, with a cataloged total of 8,740 specimens, is by far the largest in the world. It continues to grow in size and completeness due in large part to NSF funding.

Publications citing support of this grant:

Brown, B.V. 1996a. Preliminary analysis of a host shift: revision of the Neotropical species of Apocephalus, subgenus Mesophora (Diptera: Phoridae). Natural History Museum of Los Angeles County Contributions in Science. 462: 1-36.

Brown, B.V. 1996b. First record of the genus Plectanocnema Schmitz in North America (Diptera: Phoridae). Proceedings of the Entomological Society of Washington. 98: 608-609.

Brown, B.V. 1996c. A further species of Apocephalus, subgenus Mesophora (Diptera: Phoridae) parasitic on stingless bees (Hymenoptera: Apidae: Meliponinae). Studia dipterologica. 3: 231-235.

Brown, B.V. 1997. Systematics and fossilized host-parasitoid relationships of Calamiscus Borgmeier (Diptera: Phoridae). Journal of Natural History. 31: 1253-1259.

Brown, B.V. in press. Parasitic phorid flies: a previously unrecognized cost to aggregation behavior of male stingless bees. Biotropica.

Brown, B.V. in press. Revision of the Apocephalus attophilus-group of ant-decapitating flies (Diptera: Phoridae). Contributions in Science.

Brown, B.V. submitted. Phoridae. in Nadkarni, N.M. & Wheelwright, N.T. (editors). The Natural History and Ecology of Monteverde, Costa Rica: Background to Conservation. Oxford University Press.

Brown, B.V. submitted. The undescribed male of Beckerina sinefurca Borgmeier and the recognition of Neotropical Beckerina (Diptera: Phoridae). Entomological Problems.

Brown, B.V. submitted. New species and records of Gymnophora Macquart (Diptera: Phoridae) from southeast Asia. Contributions in Science.

Brown, B.V. and D.H. Feener, Jr. in press. Parasitic phorid flies (Diptera: Phoridae) associated with army ants (Hymenoptera: Formicidae: Ecitoninae, Dorylinae) and their conservation biology. Biotropica.

Feener, D.H., Jr. & B.V. Brown. 1997. Diptera as parasitoids. Annual Review of Entomology. 42: 73-97.