Triepeolus

Robertson, 1901

Longhorn-cuckoo bees

Species Guides

23

Triepeolus is a of cleptoparasitic (cuckoo) bees in the Apidae, tribe Epeolini. With at least 140 described , it is the second-largest genus of cleptoparasitic apid bees worldwide. Species in this genus are kleptoparasites that lay their in the nests of other bees, primarily long-horned bees in the tribe Eucerini, particularly genera Melissodes and Svastra. The genus has a New World distribution, with its greatest diversity in North and South America, though at least one species occurs in the Palearctic region.

Triepeolus utahensis by (c) Kylie Etter, alguns direitos reservados (CC BY), carregado por Kylie Etter. Used under a CC-BY license.Triepeolus utahensis by (c) Kylie Etter, alguns direitos reservados (CC BY), carregado por Kylie Etter. Used under a CC-BY license.Triepeolus denverensis by (c) Elliott Gordon, alguns direitos reservados (CC BY), carregado por Elliott Gordon. Used under a CC-BY license.

Pronunciation

How to pronounce Triepeolus: /triːɛpˈiːələs/

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Identification

Triepeolus can be distinguished from related cleptoparasitic by morphological features of the pseudopygidial area in females. In the simplex species group, females possess a trapezoidal or triangular pseudopygidial area with bright, reflective setae and a concave margin. Males typically have long , a trait reflected in the 'longhorn-cuckoo bees.' Identification to species level requires detailed examination of external morphological characters and often benefits from barcode data.

Images

Distribution

New World distribution, with greatest diversity in North and South America. The simplex group is entirely New World. At least one species (T. cecilyae) has been recorded from Chile, representing the first record for that country. A single species has been recorded from Europe (Palearctic region).

Host Associations

  • Melissodes - kleptoparasitePrimary in tribe Eucerini
  • Svastra - kleptoparasitePrimary in tribe Eucerini; specific association with S. sabinensis documented for T. penicilliferus
  • Xenoglossa pruinosa - kleptoparasiteDocumented for T. remigatus; host- interactions characterized by and avoidance
  • Caupolicana yarrowi - kleptoparasiteDocumented for T. grandis
  • Tetraloniella - kleptoparasite for Palearctic Triepeolus

Life Cycle

Cleptoparasitic. Females enter nests and lay in provisioned by the host . The Triepeolus larva consumes the host's pollen and nectar provisions, often killing the host larva in the process.

Behavior

do not gather pollen or construct nests. Females exhibit parasitic involving rapid visits to nests, preferentially entering while the host is foraging—potentially a strategy to avoid detection. Interactions between T. remigatus and its host X. pruinosa are characterized by minimal aggression and primarily tolerant or avoidant behaviors from both parties. Males have been observed resting on flowers.

Ecological Role

As , Triepeolus function as regulators of their species. They contribute to bee dynamics and may influence host nesting and distribution.

Human Relevance

Males and females may be observed visiting flowers for nectar, making them visible to observers. One was featured in a native mural at the UC Davis Bee Haven as an example of cleptoparasitic bee .

Similar Taxa

  • EpeolusSister in tribe Epeolini; both are cleptoparasitic bees with similar . Distinguished by morphological characters and associations (Epeolus primarily parasitizes Colletes).
  • SphecodesAnother cleptoparasitic , but in Halictidae (sweat bees) rather than Apidae; similar cuckoo bee lifestyle but different family and associations.
  • NomadaLarge of cleptoparasitic bees in Nomadinae, tribe Nomadini; similar cleptoparasitic habit but different tribe and typically different associations (often Andrenidae).

More Details

Subgeneric classification

A 2024 phylogenomic study revised the subgeneric classification of Triepeolus, proposing three new subgenera: Placopyge, Pseudodoeringiella, and Rightmyera. The study also removed Argyroselenis, Pyrrhomelecta, and Trophocleptria from synonymy with Epeolus and recognized them as valid subgenera of Epeolus.

Species diversity

With at least 140 described , Triepeolus is the largest in its tribe (Epeolini) and the second-largest genus of cleptoparasitic apid bees globally. The simplex species group alone contains 18 valid species, seven of which were newly described from North America in 2024.

Evolutionary history

Phylogenomic analysis indicates that Triepeolus and its sister Epeolus originated between the early Oligocene and early Miocene, most likely within the Holarctic region. The Bering Land Bridge served as the route by which epeoline bees reached the Old World.

Sources and further reading