1) Arthropod genus 2) Genus psithyrus 
Cuckoo bumblebees are members of the subgenus Psithyrus in the bumblebee genus Bombus. Until recently, the 29 species of Psithyrus were considered to constitute a separate genus. They are a specialized lineage which has lost the ability to collect pollen and to rear their brood. They have lost the worker caste and produce only sexuals, male and fe...
(from the article `bumblebee`) ...to Australia and New Zealand to aid in the pollination of various flowering plants. Most authorities recognize two genera: Bombus (see ...
[n] - a large bee that resembles the bumblebee but lacks pollen-collecting apparatus and a worker caste
genus Psithyrus noun a large bee that resembles the bumblebee but lacks pollen-collecting apparatus and a worker caste