SHARP-EATMAN
NATURE
PHOTOGRAPHY
TRIEPEOLUS RUGOSUS - TRAITS
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Nesting Behavior
Triepeolus
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male and female Triepeolus traits.
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TRAITS OF MALE TRIEPEOLUS RUGOSUS - 2025
TRAITS OF MALE TRIEPEOLUS RUGOSUS
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.
DISTINCTIVE TRAITS: (1) the integument of mesepisternum is rugose; and (2) the apical third of the wings (both forewings and hindwings) is dark, and the delineation between dark and light wing areas well demarcated.
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 nearly ninety degrees.
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 dark brown on the outer third, and the demarcation between light and dark areas is sharp. The lighter part of the wings is transparent light brown. 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 - As with the female, differences in the rugose mesepisternum, the one-third-dark wings and the tergal bands differentiate Triepeolus rugosus from T. donatus.
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.
Hind wing and forewing of male Triepeolus rugosus: showing dark outer third,
clearly demarcated from rest of wing.
The wrinkled mesepisternum of a male Triepeolus: examples from several bees
The following are various examples (from different males) of the rugose mesepisternum of the male Triepeolus rugosus.
TRAITS OF FEMALE TRIEPEOLUS RUGOSUS
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.
DISTINCTIVE TRAITS: (1) the integument of mesepisternum is rugose; and (2) the apical third of the wings (both forewings and hindwings) is dark, and the delineation between dark and light wing areas well demarcated.
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 some 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.
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: 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 nearly right angle.
FOREWING: The outer third of the forewing (as well as the hind wing) 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.
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. Its wings are not dark on the apical third. 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). Both are easily distinguished from this bee.
A female Triepeolus rugosus from Gainesville Mellssodes apicatus nest site
FEMALE #1. This is a close-up of the a Triepeolus rugosus 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 and its face somewhat elongate.
FEMALE #2. This is a female Triepeolus found at the nest site on April 27, 2025.
Face of female
Additional view of bee's face, with head tilted slightly forward.
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.
The wrinkled mesepisternum of a female Triepeolus rugossus from the nest site
This series shows examples of the wrinkled mesepisternum of three different female Triepeolus rugosus
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