Melissodes ablusus
Scientific Classification
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Binomial Name
Melissodes ablusus
Melissodes ablusus Cockerell is a rare species of Nearctic bee, currently having only 17 publicly documented occurrences, 13 of which are preserved specimens (GBIF Secretariat, 2023), and 4 of which are wild (DeBano et al., 2024; Wilson et al., 2025). Melissodes species are colloquially referred to as “long-horned bees.” Because of its rarity, M. ablusus has no common name, and therefore inherits the genus level common name. Like all Melissodes, male M. ablusus have long antennae, and the females have short antennae in comparison (see “Genus Melissodes” page for more information). This species resides in the subgenus M. (Callimelissodes) Laberge along with 14 other species and there are currently no records of a subspecies of M. ablusus (Laberge, 1961). The two sexes differ in both antennal length and scopal hair density, although when first described Cockerell didn’t include any male descriptions. All the male identifications and descriptions are based on structure and color; none of the males found were with females (Laberge, 1961).
Description and Identification
Melissodes ablusus are medium sized setacouse bees. Females range from 9 to 11 millimeters in length and 3.5 to 4 millimeters in width. Males are a bit smaller, only being about 10 millimeters in length and 3 millimeters in width with little variation. The female's first flagellar segment is on average 2.12 times the size of the second flagellar segment (standard deviation 0.042). The males are the opposite where the second flagellar segment is on average 4.57 times the size of the first flagellar segment. Female wing length is 2.73 millimeters on average (standard deviation 0.199 millimeters), and male wing length is 5.19 millimeters on average. Females have an average of 11.22 hamuli (standard deviation 0.223), while males have an average of 11 (Laberge, 1961).
Female
The integument shares the same color as M. lupinus (black), differing at the eyes which are a green to yellowish green, the wing membranes which are slightly clouded with a brownish black color, and the tibial spurs that can appear yellow to a reddish brown. The clypeus has small crowded punctures that are often round and separated by less than half the diameter of a puncture. However, at the base of the clypeus the punctures are slightly further apart. The surface of the clypeus is dulled by irregular shagreening and does not have a well-defined boss or median carina apically. The supraclypeal area is shiny and smooth with no shagreening. The flattened lateral areas of the vertex near the apices of both compound eyes are moderately shiny and have small round punctures mostly separated by less than half the diameter of a puncture with sparse shagreening. The last flagellar segment is distinctly longer than broad and is rounded distally. The eyes in the facial view are slightly less than three times as long as they are wide, and converge strongly toward the mandibles. The four maxillary palpal segments decrease in length from basal to apical in a ratio of about 6:5:5:1. The galeae is narrow and has an opaque surface that is dulled by dense coarse tessellation. The mesoscutum has a large posteromedian area that is impunctate. This area is about one third of the total mesoscutum surface, and the punctures that surround the impunctate area are small. Posteromedially, the surface is shiny, but tends to be dulled anteriorly and laterally by fine shagreening. Punctures of the scutellum are sparse medially, and often separated by more than one puncture diameter; the surface is dulled by fine shagreening. The metanotum is shiny and opaque medially and has abundant round punctures that are noticeably smaller than those of the mesoscutum. The punctures are mostly separated by half the diameter of a puncture or less and the surface of the non-medial metanotum is opaque and dulled by delicate and fine tessellation. The mesepisternum has a lateral surface with punctures that are smaller than that of the mesoscutum. The punctures of the mesepisternum’s lateral surface are crowded and separated by half a puncture diameter or less. The surface is moderately shiny to dull with shagreening. The propodeum’s dorsal surface is reticulorugose except medially and is posteriorly rugae. The ruga often assume the aspect of discrete large punctures. The propodeum’s posterior surface has distinct round punctures that are separated by one-half to one diameter of a puncture, except the impunctate upper median triangular area. The lateral surfaces of the propodeum are opaque, have crowded punctures, and are dulled by fine, delicate tessellation (Laberge, 1961).
The first metasomal tergum’s integument basal half is moderately shiny to shiny with very fine reticulotransverse shagreening, and crowded with shallow punctures. The second tergum’s interband zone has deep, round, regular punctures that are separated by one-half to half a puncture diameter. The apical area of the second tergum has abundant punctures that are deep and round, mostly separated by one-half to half a puncture diameter except for the narrow apical impunctate area. Integument of the second tergum is shiny with very fine reticulotransverse shagreening. Both tergum 3 and 4 are similar to tergum 2, although the apical area is obscured by distal pubescence. The pygidial plate is narrow, U-shaped, and its sides are subparallel in the apical half (Laberge, 1961).
M. ablusus can vary in setal coloration; the two extremes are as follows. The darkest specimen has an all-black head. The thorax is a dark brown except for sparse pale-ish brown to ochraceous hairs that surround the base of the wing. These sparse pale-ish brown to ochraceous hairs are also present dorsally on the metanotum and propodeum. The metasoma is completely dark brown except for the second tergum’s basal zone which is covered in ocheraceous pubescence. The basal zone of the second tergum has wide oblique fasciae of pale pubescence present laterally. The fasciae may almost meet medially and can reach the apical margin laterally. However, if this happens, the fasciae is dark brown toward the middle, and apicolaterally. The third tergum’s distal pale pubescent band is medially brown. The pale pubescence is separated from the apical margin of tergum three by dark brown pubescence and suberect hairs. The fourth tergum’s apical pubescent band is dark brown but can be a pale brown laterally. Terga five and six have no lateral pale hairs. The leg hairs are a dark brown, whereas the scopal hairs are a yellowish white. The palest specimen has a dark brown face mixed with pale ochraceous, except the clypeus; dark brown on vertex. The face is predominantly brown along the inner margins of the eyes surrounding the antennal fossa and adjacent supraclypeal area. The thoracic hairs tend to be ochraceous to pale ochraceous. However, the mesoscutum has a large dark brown patch of hair posteromedially that extends forward usually to a transverse line at the anterior margins of the tegulae. The scutellum’s median area has a large dark brown patch of hair. The first tergum has long pale ochraceous hairs both basally and laterally. The second tergum’s basal zone has long pale ochraceous pubescence. The second tergum’s interband zone has short and relatively simple suberect dark brown to dark ochraceous hairs. Distal, pale pubescent band of the second tergum is broad and arched; narrowly interrupted medially and reaches or almost reaches the apex of the tergum laterally. Tergum two’s apical area has short and simple appressed to suberect, brownish ochraceous hairs except for a narrow glabrous margin. The third tergum is similar to the second but the interband zone often has sparse, appressed, pale pubescence. The pale distal band of the third tergum is broader than that of the second tergum, narrowly interrupted medially, and extends to the apical margin laterally. The median third of tergum four has a narrow dark pubescent area along the apical margin. The fourth tergum’s broad, pale, pubescent band has scattered brown pubescence and is located basally from the narrow dark pubescent area. Terga 5 and 6 have dark brown hairs; tergum 5 has small lateral pale tufts. The sternal hairs are brown except at extreme apical and lateral margins of sterna 3, 4, and 5. The legs usually have pale ochraceous to white hairs. The distitarsi is usually brown, along with the coxae, trochanters, basitibial plates, and femora. The fore and middle tibiae and tarsi are dark brown except for the outer apical surfaces of the tibiae. The hind tibia and basitari’s inner surfaces are a dark brown, whereas the middle basitari’s inner surfaces are more of a dark reddish brown. The scopal hairs are white to ochraceous, and the rachis of each setae do not extend very far beyond the plumose part. Each hair of the scopa usually has 4 to 6 branches on each side, these only occur on the apical most half of the rachis, and sometimes less (i.e. further out on the rachis). Two to several scopal hairs that are on the posterior part of the tibia’s apex are almost sinuous and bent to shape of the surface of apical glabrous tibial area (Laberge, 1961).
Male
The integument shares the same color as M. lupinus (black), differing at the eyes which are gray; the flagellum which is yellow to red below (except for the first segment) and dark brown above; the clypeus and mandibular base which is cream colored (almost as pale as the labrum); the wings which have hyaline membranes and black to brown veins; terga 2-5 are opaque brown and occasionally translucent and yellowish apically; the disitarsi are rufescent; and the tibial spurs which are yellow to white. The eyes strongly converge toward the mandibles, and tend to be about 3/8 as wide as they are long. The minimum length of the first flagellar segment is less than 1/5 of the maximum length of the second segment. Flagellar segments 3 through 10 (and the base of 11) have ventrolateral shiny longitudinal depressions. The penultimate flagellar segment is twice as long as it is wide, and the ultimate segment is far less than three times as long as it is wide. The maxillary palpal segments decrease from basal to apical in a ratio of about 2.2:2.0:2.0:1.0. The apical margin of the broad flap on sternum 4 is not emarginate medially, and sterna 3 and 5 are distinctly convex apically. The remainder of the characteristics are the same as the female described above except as follows: the punctures on the clypeus are more widely spaced and slightly coarser; the mesepisternum’s lateral surface is shiny with very sparse shagreening; the first tergum’s basal 4/5 is dense and regular punctures; terga 2-4 are apically impunctate (Laberge, 1961).
The 7th sternum’s median plate is flat and lies in the normal ventral plane, not rotated sideways. The apicolateral angles of sternum 7 are rounded, the sternum briefly narrows into a short, broad neck, and has abundant short hairs ventrally. The membranous area between the inner edge of the lateral plate and the lower part of the median plate is almost completely obscured and appears as a thin line. The 8th sternum usually has one or two hairs apicomedially, and no apical hairs medially. The apicoventral tubercle of sternum 8 is unidentate, rounded apically, and slightly surpasses the apical margin medially. The gonostylus is less than two-thirds the length of the gonocoxite and is capitate. The ventral area of the gonostylus has short sparse hairs near the base, and no hairs laterally. The spatha is sinuate apically and about three times as wide as it is long. The penis valve’s dorsolateral lamella ends at the spatha and isn’t turned inward to form a tooth just in front of the spatha (Laberge, 1961).
While it’s likely there are wide variations of setal color in male M. ablusus, only one specimen has currently been described. The head and thorax are pale ochraceous; the dorsum of the thorax is yellowish; the scutellum has sparse brown hairs medially. The first tergum has long pale ochraceous hairs on the basal four-fifths. The second tergum has white to pale ochraceous hairs. The basal and distal pubescent bands are white, although the distal pubescent band is often narrowly interrupted medially. The interband zone has ochraceous suberect hairs, and the apical areas are glabrous. Tergum 3 is similar to the second terga, but the basal tomentum is brown, the distal pubescent band is not interrupted medially. Terga 4 and 5 are similar to tergum 3, but have simple, suberect apical hairs that are often brown at least medially. The fourth and fifth terga’s distal pale pubescent bands are not narrowly interrupted and reach the apical margin except medially. Terga 6 and 7 have dark brown hairs. The sternal hairs are pale ochraceous and usually darkened medially. The leg hairs are white to pale ochraceous, however, the inner surfaces of basitarsi and usually the distitarsi are often pale rufescent to yellow (Laberge, 1961).
Location and Habitat
M. ablusus have very few documented occurrences in general, let alone from the wild. From the publicly available records, and postulates of the subgenus M. (Callimelissodes), there can be an assumed range. M. (Callimelissodes) as a subgenus mostly resides in the western United States (four species reside east of the Mississippi). In 1961, Laberge showed that M. ablusus was more widespread across the mid-south of California, which matches up with the location of the subgenus. Laberge (1961) stated that he examined 3 female paratypes that were collected with the holotype (however Cockerell (1926) mentions 7 female paratypes collected with the holotype; those will be counted instead of the 3 Laberge mentioned), 6 females collected with the holotype, an additional female collected by E. C. Van Dyke, and one male collected by R. M. Bohart for a total of 15 occurrences. Only two locations were given; the female collected by E. C. Van Dyke was at Millbrae, California, and the male collected by R. M. Bohart was at Bolinas, California (Laberge, 1961). In 2024, a study about restoring pollinator habitat in Oregon overhauled the aforementioned range by showing sightings of M. ablusus outside of California (DeBano et al., 2024). Based on the study, M. ablusus was found in Zumwalt, Oregon (Fig. 1). In 2025 a survey of bees in Utah showed a presence of M. ablusus (Fig. 1) as well (Wilson et al., 2025). No further location has been given for Utah. There are currently 3 documented occurrences of M. ablusus with a date associated. With that information, a vague approximation of annual activity can be illustrated (Fig. 2). As of now, there are no current flower records for M. ablusus, but given its relation to M. metenuus, it is somewhat reasonable to assume that M. ablusus may be a generalist.
Fig. 1 Map showing an estimation for the known distribution for M. (Callimelissodes) ablusus. Each point represents 1 or more occurrences; occurrences that don't have coordinates are not included. The blue polygon represents the estimated distribution. Data compiled from GBIF, Wilson, J.S. et al. (2025), and DeBano, S.J. et al, (2024).
Fig. 2 A conceptually similar arrangement to that illustrated by Wilson & Carril, 2016 but was independently redrawn for this study with updated information. Green represents the most active time period; yellow represents a lesser active time period; orange represents an active time period for very few individuals.
Taxonomy and Phylogeny
M. ablusus was originally described in 1926 by Cockerell as a race of M. metenuus from Oregon. When first described as a race, M. ablusus was given no subgenus. In 1961 Laberge introduced the subgenus Callimelissodes which he notes was previously attributed to Eumelissodes, and included both M. metenuus, and M. ablusus in this subgenus. M. ablusus got re-assigned from race to species in 1961 because of the opaque, dulled, rough textured surface of the galeae in contrast to the shiny, relatively non-shagreened surface of M. metenuus. Another distinction made was in the maxillary palpi in which M. ablusus females have a segment ratio of 6:5:5:1 whereas M. metenuus females have a segment ratio of 2.3:2.3:2.0:1.0, and occasionally a fifth minute segment (Laberge, 1961).
Literature Cited
1. Melissodes ablusus Cockerell, 1926 in GBIF Secretariat (2023). GBIF Backbone
Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2025-09-10.
2. LaBerge, W.E. (1961) ‘A revision of the bees of the genus melissodes in north and Central America.
part III (hymenoptera, Apidae)’, The University of Kansas science bulletin, 42(5), pp. 283–663.
doi:10.5962/bhl.part.9821.
3. Wilson, J.S. et al. (2025) ‘A checklist of the Bees of Utah’, Diversity, 17(3), p. 212. doi:10.3390/d17030212.
4. DeBano, S.J., H. Schmalz, M.M. Rowland, J. Fields, P. Schreder and C. Duquette. 2024. Managing
and Restoring Pollinator Habitat in Interior Pacific Northwest Grasslands and Riparian Areas.
Available at: https://www.oregon.gov/oweb/data-reporting/HP/Pages/zumwalt-prairie.aspx
5. Melissodes metenua ablusa Cockerell, 1926, Pan-Pacific Ent., vol. 3, p. 85.
6. Wilson, J.S. and Messinger Carril, O.J. (2016) The bees in your backyard: A guide to North
America’s bees. Princeton, NJ: Princeton University Press.