SHARP-EATMAN
NATURE
PHOTOGRAPHY
ID GUIDE TO WILD BEES
OF THE NATIONAL BUTTERFLY CENTER
Mission, Texas
EUCERA LONG-HORNED BEES
Tetraloniella / Eucera / Xenoglossa
LONG-HORNED BEES
Genus Eucera or Xenoglossa
Formerly Genus Tetraloniella
Before 2018, the bees featured on this page were classified for decades as Tetraloniella, a genus coined by the American entomologist William Harris Ashmead in 1899.
In 2001, the entomologist Walter Laberge undertook a comprehensive study of Tetraloniella. For this work, titled "Revision of the bees of the genus Tetraloniella in the New World,” LaBerge examined 6,504 specimens of Tetraloniella, boiling them down to 35 distinct species, which he described in painstaking detail. Among them were Tetraloniella eriocarpi, Tetraloniela wilmattae and Tetraloniella panenalbata.
LaBerge's description of the genus Tetraloniella is still helpful today -- it accurately characterizes all of the long-horned bees featured below.
Laberge characteried Tetraloniella as follows: They are small to moderate-sized bees that superficially resemble long-horned bees of the genus Melissodes. The abdomens of Tetraloniella are often banded by pale hairs. Females usually have dense, and sometimes feathery, pollen-collecting (scopal) hairs on their hind legs. Males have long antennae, and yellow or pale markings on the mandibles. The male's clypeus and labrum (the mouthparts situated above and between the mandibles) are also pale or yellow. Some males have toothlike projections on either side of the sixth segment (T6) of their abdomens.
Renaming of the genus Tetraloniella
In 2018, entomologists Dorchin et al. described the classification system for Eucerini as sprawling and messy, and they recommended a rehaul. Dorchin et al. proposed, among other changes, that bees occupying the genus Tetraloniella be resituated in the genus Eucera. New World Tetraloniella like those shown on this guide page were reclassified as Eucera (Xenoglossodes).
Since that time, more seismic upheavals in the longhorned bee universe have followed. Scientific nomenclature for longhorn bee genera is currently in a state of flux. A 2023 publication by Freitas et al. proposes the reclassification of some Eucera (Xenoglossodes) in the resurrected genus Xenoglossa.
Recommended reading:
Dorchin A, López-Uribe MM, Praz CJ, Griswold TL, Danforth BN. 2018. Phylogeny, new generic-level classification, and historical biogeography of the Eucera complex (Hymenoptera: Apidae). Molecular Phylogenetics and Evolution 119:81–92.
Freitas FV, Branstetter MG, Franceschini-Santos VH, Dorchin A, Wright KW, López-Uribe MM, Griswold TL, Silveira FA, Almeida EAB. 2023. UCE phylogenomics, biogeography, and classification of long-horned bees (Hymenoptera: Apidae: Eucerinae), with insights on using specimens with extremely degraded DNA. Insect Systematics and Diversity 7(4), 3: 1-21.
A male Eucera fasciatella
TRAITS OF TETALONIELLA
LaBerge described Tetraloniella as moderate-sized bees that often have abdomens girded by bands of pale hairs.
Female tetraloniella usually have dense, and sometimes feathery, pollen-collecting (scopal) hairs on their hind legs.
Male tetraloniella have long antennae. On males, the clypeus and labrum (the face-parts above and between the mandibles) are yellow or pale.
A female Eucera paenalbata
TAXONOMY OF EUCERA
Order: Hymenoptera
Family: Apidae
Subfamily: Eucerinae
Tribe: Eucerini
Genus: Eucera
Subgenus: Xenoglossodes
Species shown below:
Eucera (Xenoglossodes) eriocarpi Tetraloniella eriocarpi -
Eucera (Xenoglossodes) fasciatella Tetraloniella fasciatella
Eucera (Xenoglossodes) paenalbata Tetraloniella paenalbata -
Eucera (Xenoglossodes) wilmattae Tetraloniella wilmattae -
Eucera (Former Tetraloniella) Species of the Lower Rio Grande Valley
Wilmatte's Long-horned Bee
Eucera (Xenoglossodes) wilmattae
Family: Apidae
Size: 10 mm - 2/5"
Associated plants at NBC:
Skeleton-leaf goldeneye
(Viguiera stenoloba)
Blanketflower
(Gaillardia pulchella)
Hoary blackfoot
(Melampodium cinereum)
Texas palafox
(Palafoxia texana)
Mexican hat
(Ratibida columnifera)
Tiny Tim
(Thymophylla tenuiloba)
Cowpen daisy
(Verbesina encelioides)
Plant Family: Asteraceae)
When and where seen:
NBC (Hidalgo Co.)
November 2018; April-May 2019, November 2023
Dos Venadas Ranch
Rio Grande City (Starr Co.)
April 26, 2023
A female Wilmatte's long-horned bee: this is a golden bee with relatively short antennae and black eyes.
The female bee's face and thorax are covered with pale golden-brown hairs.
Dorsal view of female bee
This is a male Wilmatte's long-horned bee. The bee has a furry appearance, opaque black eyes and long antennae. Its hair is generally paler than that of the female bee.
The male Wilmatte's long-horned bee has pale-yellow jaws and a pale-yellow labrum. The bee's clypeus is bright yellow.
Pale hairs cover much of the bee's head and thorax.
A male Wilmatte's long-horned bee (Eucera wilmatte)
A female Wilmatte's long-horned bee
This species was named after Wilmatte Porter Cockerell, who first recorded it in 1917, in an article titled "Collecting Bees in Southern Texas." Cockerell discovered a single female specimen in Port Isabel, Texas, about 80 miles from Mission, where the National Butterfly Center is located. Cockerell noted that the bee was feeding on a "yellow composite" (an aster-family flower).
More than 100 years later, Wilmatte's long-horned bees still visit yellow composites at the National Butterfly Center.
Wilmatte's long-horned bees are enchanting insects. Males have bright yellow faces and exceptionally long antennae, which they curl inward at the tips like the ends of a moustache. Female bees' heads and bodies are are clothed in golden hair; males are covered in ivory hairs.
Both males and females have opaque black eyes that look like apple seeds. This trait is visible to the naked eye, and helps the casual naturalist distinguish this species easily from Melissodes long-horned bees of the Lower Rio Grande Valley, which have brightly-colored (usually green or blue) eyes.
Wilmatte's long-horned bees fly from April through November in the Valley. They are found in Cameron, Hidalgo and Starr Counties. This species' documented population is centered in South Texas. It ranges into Mexico, as least as far south Nuevo Leon, and has been sighted as far west as new Mexico. In the Valley, this species visits aster-family flowers nearly exclusively.
Fasciatella long-horned bee
Eucera (Xenoglossodes) fasciatella
Family: Apidae
Size: 10.5 mm (male)
Associated plant:
Shrubby blue salvia
(Salivia ballotiflora)
Plant family:Laminacaea
When and where seen:
May 30, 2021
Falcon State Park
Roma (Starr County)
A male Eucera fasciatella
A male Eucera fasciatella: males of this species have exceptionally long antennae.
Frontal view of male bee
The male bee has a wide face with a large ivory area, shaped like a crown topped by two knobs. The pale area covers the clypeus and extends more than halfway to the antennae.
The clypeus’s lower edge is rimmed with brown. The mandibles each have an ivory spot near the base, and are reddish toward the tips.
A male Eucera fasciatella
The shape and color of the ivory facial markings of the male Eucera fasciatella distinguish it from all other male longhorn bees of the Lower Rio Grande Valley.
In 1970, upon discovering this species, LaBerge placed the fasciatella long-horned bee in a new genus, which he named Pectinapis. Some females of this genus had comb-like hairs above the clypeus; all had hairy facial depressions above the clypeus . LaBerge speculated that female Pectinapis used their novel facial apparatus to rake pollen from flowers. He noted that some anthophorine (digger) bees had similar facial hairs, which they used to gather pollen. (The most common Valley species with such clypeal hairs is Anthophora capistrata, which collects pollen principally from salvia.)
Michener later reclassified Pectinapis fasciatella in Bees of the World: he felt that the bee's unusual facial characteristics did not merit the conjuring of a new genus. He cast this species into the same genus as Wilmatte’s long-horned bees, rechristening it Tetraloniella (Pectinapis) fasciatella.
CITE THIS PAGE: Sharp, Paula and Ross Eatman. "Eucera." Wild Bees of the National Butterfly Center of Mission, Texas. 15 Jan. 2019, http://www.wildbeestexas.com. Accessed [day/month/year guide accessed].
Goldenweed long-horned bee
Eucera (Xenoglossodes) eriocarpi
Family: Apidae
Size: 7-9 mm (male and female)
Associated plants:
Texas palafoxia
(Palafoxia texana)
Arkansas dozedaisy
(Aphanostephus skirrhobasis)
Plant family: Asteraceae
When and where seen:
April 26, 2023
Dos Venadas Ranch
Rio Grande City, TX (Starr Co.)
Male Eucera eriocarpi
A male Eucera eriocarpi
Frontal view
Close-up of face: the clypeus of the male Eucera eriocarpi is ivory or pale yellow with a gold band on the bottom rim.
The mandibles are pale-yellow or ivory at the base. They are red in the middle and black at the tip.
Male Eucera eriocarpi are covered primarily with ivory hairs; on some individuals of the species, the hairs may be pale-rust or golden. The male bee has very long antennae, which appear red to the naked eye; underneath they are yellow or orange. The male's clypeus and labrum are yellow.
The male Eucera eriocarpi can be confused easily in the field with Eucera wilmattae, shown directly above. On the latter, the last 3 1/2 flagellar segments of the antennae are dark; the male Eucera eriocarpi lacks this trait.
Female Eucera eriocarpi and E. wilmatte can be separated by the following traits. (1) On the female Eucera erocarpi, the pale hair bands on the abdomen run together; on E. wilmatte, the tergal bands are more distinct and separated. (2) On the female E. eriocarpi, the labrum is all pale; on the female E. wlmattae, the labrum is partly or entirely black.
Eucera eriocarpi ranges throughout Mexico and much of Texas and the southwestern United States. It is found as far west as Nevada and as far north as Kansas.
Woolly-white long-horned bee
Eucera (Xenoglossodes) paenalbata
Family: Apidae
Size: 10.5 mm (female)
Eucera paenalbata is a small bee with a robust build; white and pale-orange thorax hairs; golden-pink tegulae; and pale-blue eyes.
Dorsal view of female bee and the pale-rust hairs on its thorax
Close-up of the female's vertex & thorax
Frontal view of female bee
Eucera paenalbata is a small and pretty long-horned bee, with pale-blue eyes; white and light-orange thorax hairs; golden-pink tegulae; and an abdomen clothed in pale hairs. This species’ scientific name (paen- or “almost”) is a nod to Eucera albata, a similar white-and pinkish-gold bee first described by Cresson in 1872.
LaBerge first described the woolly-white long-horned bee in 2001, christening it Tetraloniella paenalbata. Like Eucera wilmattae shown above, Eucera paenalbata exhibits the characteristics of the former genus Tetraloniella: the female bee’s hind-leg scopal hairs are dense and plumose. The male Eucera paenalbata has a pale clypeus and labrum, and its mandibles are pale at the base.
This species ranges from Colorado and Kansas through Texas and Tamaulipas, and as far south as Mazatlán. LaBerge recorded Eucera paenalbata feeding on purple dalea (Dalea lasiathera), a pea-family plant. The female bee found here was foraging on the composite flowers Mexican hat and cowpen daisy.
A female woolly-white long-horned bee (Eucera paenalbata)
A female woolly-white long-horned bee
Associated flora:
Mexican hat
Rabatida columniferra
Cowpen daisy
Verbesina enceloides
Family: Asteraceae
When seen:
June 21 2021
Campos Viejos Ranch,
Rio Grande City (Starr Co.)