The Bee Tribe Eucerini
An Explanation of Confusing Recent Changes in the Names of Long-horned Bees
NAMES OF LONG-HORNED BEE SPECIES
Some of the long-horned bees in this website's bee guide -- such as Tetraloniella, have been documented under two names. Why?
Before 2018, North American members of the bee tribe Eucerini, commonly known as long-horned bees, were divided into a glorious array of 14 genera (genuses). These are beautifully and succinctly described in Wilson & Carril’s comprehensive popular guide The Bees in Your Backyard.
As explained below, in 2018, a wholesale reclassification of these bee genera occurred.
Like many events promising progress, this taxonomic upheaval has created some confusion. The new system has been slow in producing converts. Prominent Internet databases visited by naturalists – among them Discover Life, Bug Guide and several useful university and museum keys -- use the pre-2018 system for naming long-horned bees. Equally notable, so do several excellent popular guide books on pollinators.
Thus, naturalists seeking information about long-horned bees may come up empty-handed, if equipped only with the new post-2018 long-horned bee names.
Accordingly, we have chosen to provide both new and old names in this website's wild be guide, in any instance where a long-used long-horned bee species name has been abandoned in the changeover.
Pre-2018 Classifications of Long-horned Bees
Prior to 2018, there were 14 accepted New World long-horned genera (genuses).
Within the United States, the 5 long-horned groups best known to the casual naturalist are Eucera (which usually appear early in the year); Melissodes (which usually appear in late summer and fall); Peponapis and Xenoglossa (small and large squash bees); and Svastra (large bees that are often sunflower specialists).
The remaining list of pre-2018 long-horned bee genera consists of 9 bee types, found exclusively in the New World (Agapanthinus, Cemolbus, Florilegus, Gaesischia, Martinapis, Melissoptila, Simanthdon, Synthrichalonia and Tetroniella). Many of these genera contain rarely-seen species, or bees found only in specialized geographical niches. A few of these genera contain only one or a mere handful of North American species.
Post-2018 Classifications of Long-horned Bees
In 2018, a group of entomologists named Dorchin, Lopez-Uribe, Praz, Griswold and Danforth published a study titled “Phylogeny, new generic-level classification, and historical biogeography of the Eucera complex (Hymenoptera: Apidae)”. Dorchin et al described the classification system for Eucerini as problematic, and they demanded a rehaul, based in part on a new analysis of DNA sequencing in various Eucerine groups.
Dorchin et al proposed, among other changes, that several long-horned genera (Peponapis, Xenoglossa, Cemolobus, and Syntrichalonia) should be demoted to subgenera and subsumed within the genus Eucera. In addition, bees formerly occupying the genus Tetraloniella were to be resituated in other genera and subgenera, and the illustrious name Tetraloniella abandoned entirely.
How the New Classification System Works
(1) Cemolobus, Peponapis, Syntrichalonia, Xenoglossa.
These four genera have been demoted to subgenera and placed within the genus Eucera. They now appear as follows:
Cemolobus => Eucera (Cemolobus)
Peponapis => Eucera (Peponapis)
Syntrichalonia => Eucera (Syntrichalonia)
Xenoglossa => Eucera (Xenoglossa)
Tetraloniella wilmattae - now called Eucera (Xenoglossodes) wilmattae
Eucera retains its genus name but is split into two subgenera:
All Old World Eucera species => Eucera (Eucera)
All New World Eucera species => Eucera (Synhalonia)
Bees formerly in the genus Tetraloniella have been moved to the genus Eucera and split into two different subgenera. The word “Tetraloniella” has been cast to the wind:
GROUP A: Tetraloniella => Eucera (Xenoglossodes)
GROUP B: Tetraloniella => Eucera (Tetralonia)
Reclassification guidelines for former Tetraloniella remain murky and unsettled. Group A contains such species as Tetraloniella albata and T. salviae, and probably includes T. eriocarpi, T. pectinapis, T. spissa and T. wilmatte.
Determining which former Tetraloniella belong in which subgenus group is not a straightforward process. According to a follow-up publication by Dorchin et al., Group A contains all Tetraloniella of the northwestern United States. Clarification of the reclassifications of various Tetraloniella is needed.
(4) All other long-horned bee genera:
These genus names of long-horned groups were not addressed by the work of Dorchin et al and remain unchanged under the new system: Agapanthinus, Florilegus, Gaesischia, Martinapis, Melissodes, Melissoptila, Savastra, Simanthdon.