The Morphology and Behavior of Dimorphic Males in Perdita Portalis
Behav Ecol Sociobiol (1991) 29:235-247 Behavioral Ecology and Sociobiology © Springer-Verlag 1991 The morphology and behavior of dimorphic males in Perdita portMis (Hymenoptera: Andrenidae) Bryan N. Danforth* Snow Entomological Museum, Department of Entomology, University of Kansas, Lawrence, KS 66045, USA Received September 3, 1990 / Accepted June 4, 1991 Summary. In Perdita portalis, a ground nesting, commu- found on flowers visited by foraging females (SH nal bee, males are clearly dimorphic. The two male morph). First discovered by Rozen (1970), the other, morphs are easily distinguished based on head size and derived, morph is strikingly modified, as judged by com- shape into (1) a flight-capable, small-headed (SH) morph parison with related bees, possessing an expanded head that resembles the males of other closely related species capsule, enlarged facial foveae, reduced compound eyes, and (2) a flightless, large-headed (LH) morph that pos- elongate pointed mandibles, a three-pronged clypeus, sesses numerous derived traits, such as reduced com- and reduced thoracic musculature, which renders it pound eyes, enlarged facial foveae and fully atrophied flightless and restricted to a life within the natal nest indirect flight muscles. The SH morph occurs exclusively (LH morph). Unlike most of the close relatives of Perdita on flowers while the LH morph is found only in nests portalis, which show continuous variation in head size, with females. While on flowers, SH males are aggressive, albeit with strong positive allometry, the males of P. fighting with conspecific males and heterospecific male portalis are truly dimorphic. and female bees, and they mate frequently with foraging Flightless, macrocephalic males are known from a females.
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