Traits of the species Brachymelecta californica​

 

Brachymelecta californica have black heads and bodies.  The abdomens of both males and females bear a distinctive pattern of pale bands that are interrupted in the middle. The pattern is formed by short dark hairs alternating with pale somewhat longer hairs.  

 

According to Onuferko et al., a trait of the thorax distinguishes this species from all other Brachymelecta:  short parallel bands, formed by dark hairs alternating with paler hairs, run lengthwise down the scutum (first upper thorax segment). 

 

Pale hairs also cover most of the mesepisternum (sides of the thorax).  The bees’ heads and faces are partly covered with pale and dark hairs.  

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​​The bees’ tegulae (plates where the wings attach) are brick-red.  Brachymelecta californica have glassy forewings that darken abruptly on the outer upper edges.  The forewings have short marginal cells and two or (more typically) three submarginal cells.  

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The upper legs of Brachymelecta californica are mostly black.  The lower legs are dark reddish brown and partly covered with short white hairs.  As is true of female cuckoo bees generally, female Brachymelecta californica lack pollen-collecting hairs on their legs, because they depend on host species to collect pollen for them.  Males tend to be larger than females.​​

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​Bee hosts of Brachymelecta californica

 

California mourning bees have been found in the nests of a variety of digger bee host species.  These include  Anthophora abrupta, A. bomboides, A. edwardsii, A. linsleyi, A. occidentalis and A. urbana urbana.  None of these digger bee species are common to the Lower Rio Grande Valley. 

 

Nonetheless, because Brachymelecta californica shows flexibility in its host choices, it might be capable of entering the nests of other Anthophora as well.  In the Valley, the dominant digger bee species are Anthophora capistrata (the masked sage digger bee) and Anthophora californica (the California digger bee).  Further research may disclose these as likely host species in the Valley.

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History of the Species Brachymelecta californica

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If you are into obscure humor, one of the funnier titles of bee entomological history reads:  

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       BRACHYMELECTA... PREVIOUSLY THE RAREST
       NORTH AMERICAN BEE GENUS, WAS
       DESCRIBED FROM AN ABERRANT SPECIMEN...

 

In June 2021, entomologists Thomas Onuferko, Lawrence Packer and Julio Genero published a research paper  bearing this tabloid title. The paper corrected a goof made by the great entomologist G. Gorton Linsley in 1939, a goof later embraced by renown bee authority Charles D. Michener in his 992-page masterpiece, The Bees of the World.

 

In 1939, Linsley had erected two new bee genera, Brachymelecta and Xeromelecta.  The latter contained a newly defined species, Xeromelecta californica.  The genus Brachymelecta contained a single male specimen, which Linsley believed did not meet the criteria for Xeromelecta.  The forewings of this specimen had two, rather than three submarginal cells, a trait that led Michener to affirm in 2007 that the bee specimen merited separate genus and species status. 

In 2021, Onuferko, Packer and Genero demonstrated through a careful, detailed analysis and visual comparison that Linsley’s seemingly unique bee was not what it seemed.  They described its assigned species as “known from just a single specimen, collected on an unknown date by ‘Morrison’ (according to the original description) and with ‘Nev.’ the only information given on the collection label, understood to mean Nevada…”.  

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Onuferko et al. sifted through a trove of Xeromelecta californica specimens in the entomology collection of Philadelphia’s Drexel University.  They discovered a continuum of bees with variations in the length of the crossvein separating the second and third submarginal cell. The forewings of some of the bees had two cells; others had three; and some even showed a combination where one forewing had two cells while the other had three. 

 

Onuferko and his co-authors consequently placed Linsley’s seemingly unique bee in the same category with those he had named Xeromelecta californica.  Under the arcane nomenclature rules of entomology, the genus name Brachymelecta took precedence over Xeromelecta, the latter genus name was shelved, and all bees from the earlier two genera were reclassified under the genus name Brachymelecta.