SHARP-EATMAN
NATURE
PHOTOGRAPHY
TRIEPEOLUS - TRAITS
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Melissodes
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Nesting Behavior
Triepeolus
This page contains information & photographs pertaining to
male and female Triepeolus traits.
To view photographs of Melissodes & Triepeolus nesting behavior, click on the image above center.
To view photographs of Melissodes apicatus, click on the image above left.
TRAITS OF FEMALE TRIEPEOLUS
Female Triepeolus found at the nest site in 2024 and 2025 site have the following traits:
SIZE: The female bees examined (12 in all) ranged between 11 and 12.5 mm.
GENERAL: The bee's head, legs and body, including the pronotal lobes and tegulae, are almost entirely black. The mandibles are reddish brown medially, and the basitarsi and tarsi are dark brown. (On the antennae of two of the specimens examined, F1 is also partly reddish-brown). The appressed hairs on the bee's head and body are white/grayish-white.
FACE/CLYPEUS: The clypeus is somewhat elongate and somewhat convex (not flat). On most specimens, the clypeus has a very weak midline. Dense white hairs cover the face above and below the antennae and along the inner edges of the compound eyes. The hind margin of the gena is carinate.
On the bees shown here, the apical rim of the clypeus is relatively short -- about 1 to 1.5 ocellar diameters beyond the lower edge of the compound eye. Nevertheless, I might note that this character may not be the best way to separate species. Because the clypeus is convex rather than flat, the angle of view affects how long the clypeus appears.
SCUTUM: The paramedian bands running longitudinally on the scutum are short and narrow but distinct and connect with the band of hairs lining the anterior edge of the scutum.
SCUTELLUM: The scutellum is roughly pitted and curved apically. The axillar spines are well-separated from the lateral edges of the scutellum, somewhat curved and moderately long.
MESEPISTERNUM: Because of the limitations of my macro lens, I was not able to judge the nature of the punctuation or setae on the mesepisternum of the 2025 Triepeolus. Nonetheless, Rightmyer highlights these traits of the mesepisterum in distinguishing Triepeolus rugosus females from similar species: (1) the mesepisternum of T. rugosus is "irregularly, deeply punctate" and the integument of the mesepisternum between punctures "rugose, tuberculate" (Rightmyer 2008).
ABDOMEN DORSAL: On T1, the apical and basal hairbands are nearly parallel. (The basal band bells outward & forward somewhat in the middle). The dark medial region of T1 is wider than the tergum's lateral hair bands. The basal hair band of T1 is entire; its apical band is interrupted. T2, T3, and T4 are not interrupted.
ABDOMEN LATERAL: On T2, the lateral swaths of pale hairs along the tergum's sides join the apical tergal band at a weakly acute angle.
FOREWING: The forewings are brown; the outer third is dark brown, and the veins are also dark brown. There are three submarginal cells.
COMPARISONS TO SIMILAR SPECIES.
Triepeolus rugosus is most similar to Triepeolus rugosus are T. atripes, T. donatus and T. georgicus. None of these, however, are spring species, and none are known to visit pickerelweed. In addition, these species differ from Triepeolus rugosus as noted below.
Triepeolus atripes can be distinguished from T. rugosus by these traits: the clypeus of T. atripes is flat and relatively short, and it has a robust midline. The paramedian bands do not reach the anterior margin of the scutum. T. atripes also lacks long, erect, simple setae on the mesepisternum (RIghtmyer 2008).
Triepeolus georgicus does not have an elongate clypeus and lacks simple, erect setae on the mesepisternum (Rightmyer 2008).
Triepeolus donatus is similar to T. rugosus in having an elongate face and erect simple setae on the mesepisternum. Triepeolus rugosus, however, is generally smaller and has "an irregularly punctate mesepisternum, with the integument between the punctures distinctly raised and somewhat tuberculate" (Rightmyer 2008).
Mitchell (1963) also noted that Triepeolus donatus females have dark hairs on the mesoscutum. This trait is not shared by the bees found at the Gainesville nest site.
Mitchell
TERGAL BANDS: I'd add that the tergal bands differ on the typical female Triepeolus donatus and the Triepeolus from the 2024-2025 Gainesville nest site. As noted, on the latter, the tergal hair bands on T2 and T3 are entire.
Rightmyer (2008) does not include this character in her description of Triepeolus donatus, but her revision includes figures of a female and a male Triepeolus donatus with interrupted tergal bands on T2 and T3; and with a narrowly interrupted basal band on T1 (p. 146, fig. 61, and p. 170, fig. 252).
A final subjective observation: I have seen
many specimens of Triepeolus donatus over the years. In the field, Triepeolus donatus has a generally darker appearance than the Triepeolus I am seeing here in Gainesville. Triepeolus donatus is also usually found on thistles, and in association with Melissodes desponsa. There were no thistles blooming near the nest site in April and May.
FLIGHT SEASON
Other Florida species known to emerge in the spring are unlikely choices: T. lunatus, T. pectoralis, T. remigatus, and T. rufithorax,
OTHER TRIEPEOLUS FOUND ON PONTEDERIA
AND AT THE NEST SITE IN SPRING 2025
Only a handful of Triepeolus have been linked to Pontederia. These include Triepeolus lunatus (Ascher & Pickering 2018), T. remigatus (Mitchell 1962), and T. rugosus (Rightmyer 2008).
I have visited various pickerelweed stands in and around Alachua County in April & May, 2025. At one of these, about 20 miles from the nest site, I found a Triepeolus feeding on pickerelweed in a marsh visited that day by many Melissodes communis. The bee was too worn to identify to species, but I was able to rule out these species: T. lunatus (lacked correct pattern of appressed hairs on T1), T. remigatus (lacked distinctive pattern of appressed hairs on scutum).
I'm not certain whether the bee was the same species as that found at the nest site, howeve. Its clypeus appeared more elongate.
I found one Triepeolus female resembling T. rugosus on May 19, flying low over the nest area, after 90% of the nests had disappeared. I preserved the specimen: On this specimen, the mesepisternum between punctures appeared more rugose than was typical of the other bees. I was able to observe this trait because the hair on the mesepisternum had been worn off.
Female Triepeolus, probably T. rugosus
FEMALE #1. This is a close-up of the a Triepeolus female found entering a Melissodes apicatus nest.
Front view of the bee
The bee's clypeus has a weak midline and is partly covered with white hairs.
The bee's clypeus is somewhat protuberant.
FEMALE #2. This is a female Triepeolus found at the nest site on April 27, 2025.
The female's clypeus has a vague midline, and is relatively short.
Additional view of bee's face, with head tilted slightly forward. One character used to separate T. georgicus from T. donatus is the length of the clypeus. This character is problematic, because the angle of view can make the protruding clypeus appear longer or shorter.
Dorsal view of thorax: the paramedian bands are narrow but distinct and reach the hairs on the front edge of the scutum.
FEMALE #3. This female Triepeolus was found at the nest site on on May 2, 2025.
Additional view of bee
Lateral view of head and thorax
Frontal view of bee
Pattern of appressed hairs on typical female Triepeolus from nest site
On all females found in 2024-2025, the pale tergal bands on T2 and T3 were entire (not interrupted). Here are three examples.
TRAITS OF MALE TRIEPEOLUS - 2025
TRAITS OF MALE TRIEPEOLUS
Two male Triepeolus rugosus are shown here.
SIZE: There is considerable size variation among the male Triepeolus population at the site -- although the 12 bees of various sizes I examined were otherwise similar. The first bee shown here measures 12.5 mm; the second measures 11 mm. Some specimens examined were as small as 10 mm.
GENERAL: The integument of the bee's head, body and legs, including the pronotal lobes and tegulae, is generally black. The hairs on the bee's head and body are white/grayish-white.
FACE/CLYPEUS: The clypeus is convex in profile. The clypeus and labrum are black. The mandibles are predominantly black, sometimes with a reddish tint medially.
The clypeus has a dense covering of silvery tomentum. This made it difficult to assess some traits -- e.g., to determine whether the clypeus has an impunctate midline, or to assess the qualities of the punctures on the labrum. On more worn specimens, these traits are more apparent.
THORAX: The pronotal lobes and tegulae are black. The appressed hairs on the scutum are grayish white. The paramedian bands on the scutum are narrow and short but clearly defined, and they reach to the front of the scutum. On less worn specimens, there are white, longish (not appressed hairs) on either side of the paramedian bands.
ABDOMEN DORSAL: The basal and apical bands of T1 are nearly parallel; the basal band of T1 is entire and the apical band narrowly interrupted in the middle. On T1, the dark medial region is a rounded roughly triangular shape (rather than quadrangular). The width of the dark medial region is wider than the pale band on either side.
ABDOMEN LATERAL: The angle at which T2 joins the pale swaths of hair on either side is weakly acute.
PYGIDIAL PLATE: the pygidial plate has a subapical ridge.
TERGAL BANDS: As on females above, the tergal hair bands on T2 and T3 are entire (not interrupted) on all of the male Gainesville Triepeolus I have examined from the nest site.
STERNUM: There are appressed white hairs on S2-S4. The hairs on S2 and S3 are all white. There are some brown hairs on S4.
FOREWINGS: The forewings are brown, and dark brown on the outer third. the veins are dark brown. There are three submarginal cells.
SIMILAR SPECIES: I concluded that the males could not be Triepeolus atripes, because on the Gainesville bees, the paramedian bands touch the anterior margin of the scutum, and the clypeus is not flattened and does not have a robust midline.
As for Triepeolus donatus - Rightmyer lacked a male Triepeolus rugosus to compare to this species. She speculated that attributes of the mesepisternum that aided in distinguishing female Triepeolus rugosus might be absent in the male T. rugosus.
Nonetheless, I might note again that attributes of the terga might be helpful here.
Rightmyer (2008, p. 146, fig. 61) shows a photograph of a male T. donatus with interrupted apical tergal bands on T2 and T3 (and an interrupted basal band on T1). These traits are not shown by the bees shown here.
Triepeolus georgicus lacks an elongate clypeus. In describing the male Triepeolus floridanus (=T. georgicus), Mitchell (1963) described its wings "subhyaline," and did not mention that the outer one third of the forewing was dark.
A male Triepeolus, probably T. rugosus
CLOSE-UPS OF TWO TRIEPOLUS MALES
MALE #1. This is a male Triepeolus measuring 12.5 mm, found at the nest site on April 12, 2025.
Alternate view of bee
Profile view of clypeus
3/4 view of clypeus
MALE #2: This is a second male Triepeolus (probably T. georgicus), measuring 11 mm, also found at the nest site on April 12, 2025.
Profile of clypeus
The clypeus is not especially long or short -- it extends somewhat past the bottom edge of the compound eye.
The apparent length of the clypeus is affected by the angle of view.
Pattern of appressed hairs on typical male Triepeolus from nest site
On all males found in 2024-2025, the pale tergal bands on T2 and T3 were entire (not interrupted). Here are three examples.
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