NovitatesAMERICAN MUSEUM PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 3029, 36 pp., 67 figures, 3 tables November 27, 1991 Evolution of Cleptoparasitism in Anthophorid Bees as Revealed by Their Mode of Parasitism and First Instars (Hymenoptera: Apoidea) JEROME G. ROZEN, JR.1 CONTENTS Abstract .............................................. 2 Introduction .............................................. 2 Acknowledgments ............... ............................... 3 Historical Background ................ .............................. 4 Evolution of Cleptoparasitism in the Anthophoridae ............. ................... 6 Systematics of Cleptoparasitic First-Instar Anthophoridae ......... ................. 12 Methods .............................................. 12 Description of the Nomadinae Based on First Instars .......... .................. 13 Description of the Protepeolini Based on the First Instar ......... ................ 13 Description of the Melectini Based on First Instars ............ .................. 17 Xeromelecta (Melectomorpha) californica (Cresson) ........... ................. 17 Melecta separata callura (Cockerell) ......................................... 20 Melecta pacifica fulvida Cresson ............................................. 20 Thyreus lieftincki Rozen .............................................. 22 Zacosmia maculata (Cresson) ............................................. 22 Description of the Rhathymini Based on First Instars .......... .................. 24 Rhathymus bicolor Lepeletier ............................................. 25 Description of the Isepeolini Based on the First Instar .......... ................. 26 Isepeolus viperinus (Holmberg) ............................................. 27 lCurator, Department of Entomology, American Museum of Natural History. Copyright © American Museum of Natural History 1991 ISSN 0003-0082 / Price $3.80 2 AMERICAN MUSEUM NOVITATES NO. 3029 Description of the Ericrocidini Based on First Instars ........ .................... 29 Aglaomelissa duckei (Friese) ................................................ 30 Mesoplia rujipes (Perty) ................................................ 32 Ericrocis lata (Cresson) or pintada Snelling and Zavortink ...... ................ 33 References ................................................. 34 ABSTRACT The methods by which cleptoparasitic antho- will rest on discovering sister-group relationships phorid bees introduce their eggs into host nests with pollen-carrying anthophorids. and the anatomical and behavioral adaptations of Comparative descriptions of the six cleptoparas- their first instars to kill host immatures are de- itic groups are based on descriptions (or redes- scribed and analyzed. The information is derived criptions) and illustrations of the hospicidal first from the literature, from new field studies, and instars ofthe following species: Xeromelecta (Me- from first instars described here. The study iden- lectomorpha) californica (Cresson), Melecta se- tifies six distinct cleptoparasitic groups: the No- parata callura (Cockerell), Melecta pacificafulvida madinae, Protepeolini, Melectini, Rhathymini, Is- Cresson, Thyreus lieftincki Rozen, Zacosmia ma- epeolini, and Ericrocidini, and each is probably culata (Cresson), Rhathymus bicolor Lepeletier, monophyletic. The lack ofsimilar information re- Isepeolus viperinus (Holmberg), Aglaomelissa garding Coelioxoides and the Osirini (two groups duckei (Friese), Mesoplia rufipes (Perty), Ericrocis recently identified as being unrelated to the No- lata (Cresson) or pintada Snelling and Zavortink. madinae) leaves open the possibility that the An- Illustrations offirst instar Triepeolusgrandis Friese, thophoridae may contain eight cleptoparasitic Townsendiella pulchra Crawford, and Protepeolus groups. It is suggested that each group represents singularis Linsley and Michener are presented to a separate evolutionary development of clepto- exemplify their lineages. parasitism in the family, although some evidence Females of Aglaomelissa duckei and Mesoplia points to a common parasitic ancestor for the Is- rufipes are reported to introduce their eggs into epeolini and Ericrocidini. Proof of separate evo- host cells through small holes they make in the lutionary origin ofcleptoparasitism in each group closures. INTRODUCTION This paper investigates the evolutionary ism and first instars is derived from previ- relationships of the cleptoparasitic antho- ously published accounts and from new data phorids through an analysis of (1) the mode presented below under Systematics of Clep- of parasitism of cleptoparasitic taxa and (2) toparasitic First-Instar Anthophoridae. the anatomy of their first instars. Mode of Because the apomorphies used here are as- parasitism is the manner in which the clep- sociated only with cleptoparasitism, the toparasitic female introduces her egg into the question as to what pollen-gathering groups host cell, and how the host egg or larva is gave rise to the cleptoparasitic lineages is be- eliminated, allowing the cleptoparasitic off- yond the scope of this study. We as yet know spring to develop on the stored provisions. too little about first instars of nonparasitic The first instars of all known cleptoparasitic bees to recognize other kinds of first-instar anthophorids kill the hosts' young, and the synapomorphies that link cleptoparasites and anatomies ofthese hospicidal first instars re- food-gathering lineages. veal striking modifications to accomplish this Cleptoparasitism is the relationship in purpose. Hence the morphology ofthese first which the young ofone bee species feeds and instars is an integral part ofthe mode ofpar- develops on the food stored for the young of asitism. Knowledge about mode of parasit- another species. This is different from social 1991 ROZEN: CLEPTOPARASITISM IN ANTHOPHORID BEES 3 parasitism in which the parasite female lives not subsequent instars, shows the most pro- in the nest of the host species and her off- nounced anatomical modifications involved spring are cared for by the female or females with its hospicidal activities.2 Cleptoparas- of the host species. In the Anthophoridae, ites in other bee families have evolved a wid- social parasitism is found only in the Allo- er range ofmodes ofparasitism thanjust those dapini (see Michener, 1974: 227, for an over- found in the Anthophoridae. Depending upon view). the group, parasitism may be accomplished Eggs of cleptoparasitic anthophorids are (1) by the cleptoparasite female opening the introduced into host cells in one oftwo ways: host cell and killing and removing the host's either the cleptoparasitic female enters the young before she oviposits and reseals the cell open cell while the host is away foraging and (larvae nonhospicidal) (e.g., Sphecodes, Ho- hides her egg by inserting it into the cell wall plostelis), and (2) by the cleptoparasite egg (and/or cell lining), or the cleptoparasite being introduced into an open or closed cell makes a small opening in the closure (or wall) and one or more instars, but not the first of a cell that has already been sealed, inserts instar, being hospicidal (e.g., Coelioxys, Stel- an egg through the hole into the cell lumen, is). and then reseals the opening. Presumably both Unless stated otherwise, specimens de- mechanisms have evolved more than once scribed are in the collection of the American in the family. Museum of Natural History. The hospicidal first instars of the clepto- parasitic anthophorids exhibit behavioral and anatomical modifications that enable them ACKNOWLEDGMENTS to seek out, identify, and kill host eggs or Many ofthe cleptoparasitic first instars were larvae. The universal (but not necessarily ho- collected while I was in residence at biological mologous) feature of these hospicidal larvae field stations. I wish to thank the personnel is attenuate, tapering, sharp-pointed, usually of the following stations for their assistance elongate mandibles used to dispose the hosts' and hospitality: William Beebe Memorial young. Head capsules are modified and Laboratory, Trinidad, West Indies (New York strengthened in various ways in association Zoological Society); Cedar Point Biological with the increased mandibular musculature Station, Ogallala, Nebraska (University of and perhaps with sclerotization that shields Nebraska); and Southwestern Research Sta- the parasitic first instar from host larvae or tion, Portal, Arizona (American Museum of competing cleptoparasitic young. Larval mo- Natural History). bility is important for finding hosts, and in The completeness of this study was aided some lineages modifications of the abdomi- by the loan or donation of specimens from nal apex (such as the development of a py- the following specialists: Frederick D. Ben- gopod) are adaptations for crawling. Other nett, University of Florida, Gainesville; lineages lack obvious anatomical modifica- Charles D. Michener, University of Kansas, tions for crawling but still must crawl, per- Lawrence; Robbin W. Thorp, University of haps by body movement alone. Some larvae California, Davis; Philip F. Torchio, USDA have lateral body extensions, presumably en- Bee Biology and Systematics Laboratory, Lo- abling them to float on liquid provisions while gan, Utah. they seek and kill host young. There is a spec- trum of anatomical features involved with 2 Among the parasitic anthophorids, instars after the identifying host immatures (or immatures