Leafcutter and Mason Bees: a Biological Catalogue of the Genus Megachile of the Neotropics Anthony Raw

FOREWORD

This inventory is a labour of Sisyphus. I have been compiling it for years. With 290 references and thousands of citations in the text it is a formidable task. Additional references are continually coming to light. Despite the unfinished state of the work, I have been persuaded that people will find it useful in its present state. In making it available I ask the reader to inform me of errors and omissions, which I shall be happy to include in the inevitable revisions.

A major part of this investigation was made possible with an award from the Royal Society of London, which allowed me to spend a sabbatical at the University of Oxford. Visits to the British Museum (Natural History) were made possible with grants from the British Council and the Conselho Nacional de Pesquisas [CNPq [Brazilian National Research Council]. CNPq also my financed visits to the Universidade Federal do Paraná in Curitiba, and the Museu Nacional and Instituto Osvaldo Cruz, both in Rio de Janeiro. The Smithsonian Institution provided a research grant to visit the National Collection in Washington and also the collections in the American Museum of Natural History, New York and the Academy of Natural Sciences in Philadelphia. I am sincerely grateful to these Institutions for their support.

I have received on loan more than 4,000 specimens of neotropical Megachile. The following entomologists have provided me with specimens which have been invaluable for this work. I thank Mr. M. C. Day and Mr. G. R. Else, British Museum (Natural History), London; Mr. C. O'Toole, University Museum, Oxford, England; Dr. R. M. McGinley, Smithsonian Institution; Dr. J. R. Rozen of the American Museum of Natural History, New York; Dr. R. B. Roberts, Rutgers University; Dr. C. D. Michener, University of Kansas; Dr. G. E. Bohart and Dr. Terry L. Griswold, Bee Biology and Systematics Laboratory, U.S.D.A., Logan, Utah, U.S.A.; the late Dr. G. C. Eickwort, University of Cornell; Dr. W. E. LaBerge, Illinois Natural History Survey; Dr. G. Alayon García, Cuba; Dr. D. Roubik, Smithsonian Tropical Research Institute, Panamá; Dr. Edgar Ormachea Acurio, Universidade Nacional San Antonio Abad del Cusco, Peru; F. Fernández, Universidad Nacional de Colombia, Bogotá; Sr. J.A. Rafael, Instituto Nacional de Pesquisas da Amazônia, Manaus and Dr. W. L. Overal, Museu Paraense Emilio Goeldi, Belém and Padre Jesus Santiago Moure of the Universidade Federal do Paraná, Curitiba. Dr. Claire Villemont of the Musée National de Histoire Naturelle, Paris kindly delivered by hand many of the types of Vachal. Mr. Christopher O'Toole of the Oxford University Museum and Dr. V. O. Becker of Brasilia have been of great assistance during this study.

INTRODUCTION

Members of the genus Megachile are among the best known bees (O’Toole & Raw 1991). Here I have followed Michener et al (1994) and treated the group as a single genus combining Megachile with Chalicodoma. They are called "leaf-cutter bees" because the females of most species cut leaves and petals to line their nests. Others are the "mason bees" because they construct their nests with resin, mud or leaves chewed into pulp. The neotropical species are from half to four times the length of a honeybee. The earliest known member of the genus is neotropical; from Miocene amber of the Dominican Republic (Engel 1999).

The aim of this inventory is to disentangle some of the confusion that has existed for many years over the identification of the species of Megachile from the Neotropics. I hope it will help in the identification of species, stimulating studies on their biology and enabling researchers to better assess the roles of the bees as pollinators. The inventory indicates the subgenera to which most of known species belong. For each species the valid name and changes of names are listed and information on the bee’s biology and its geographical distribution are given. The subgenera are given to which 395 neotropical species belong, including 9 Old World species introduced to the region during historical times. Dalla Torre (1896) listed 92 neotropical species that are now included in the genus Megachile. Three neotropical species were erroneously placed at some time in the genus Megachile. Their present statuses are indicated below. There are also three nomina nudae. Nomenclatural questions of subgenus or species groups and of subspecies have not been addressed.

It is impossible to place the species of Megachile in their correct subgenera with any certainty without examining the type specimens. Nonetheless, a number of authors have done so without stating the situation. In order to improve the authority of this work, to date I have examined 246 type specimens of neotropical Megachile. In all the cases where “Examined” is stated I have examined the holotype. In those cases where I have not done so, the basis of my decision is clearly stated.

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