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Dianthidium singulare (Cresson, 1879)


Scientific Name: Dianthidium singulare (Cresson, 1879)

Common Name: Singular Pebble Bee


Anthidium singulare Cresson, 1879: 207 [♀].

     Holotype ♀. USA, Nevada, by Morrison [ANSP no. 2400].

Dianthidium singulare var. perluteum Cockerell and Cockerell, 1904, in Cockerell, 1904: 23 [♀]. Synonymy by Grigarick and Stange (1968: 54).

     Syntypes ♀. USA, California, Wilson’s Peak and Strawberry Valley, by Dr. Davidson [AMNH].

Dianthidium singulare melanognathum Cockerell, 1925: 363 [♀]. Synonymy by Grigarick and Stange (1968: 54).

     Holotype ♀. USA, California, Fresno County, Huntington Lake, at 7000 ft., 7 July 1919, by E.P. Van Duzee [CAS no. 1745].


Taxonomic notes: Cockerell (1904: 23) was the first to recognize Anthidium singulare Cresson, 1879 as a Dianthidium Cockerell, 1900.

The ♂ of Dianthidium singulare perluteum Cockerell and Cockerell, 1904 was briefly described by Cockerell (1925: 363) and Michener (1935: 23); Timberlake (1943: 75) provided a bried description of the ♂ of D. singulare (Cresson, 1879).

Cockerell (1925: 363), Michener (1935: 23) and Timberlake (1943) recognized Dianthidium singulare perluteum Cockerell and Cockerell, 1904, as a valid subspecies, though in his revision, Timberlake (1943) did not include Dianthidium singulare melanognathum Cockerell, 1925 as a synonym or valid taxon. Michener (1951: 1145) recognized all three taxa as subspecies, but Grigarick and Stange (1968: 54) subsequently treated them as conspecific.

Timberlake (1943: 75) incorrectly attributed D. singulare perluteum to T.D.A. Cockerell only, who was listed as the sole author of the paper (Cockerell 1904: 23), though both he and Wilmatte Cockerell are included with the original description (see Cockerell 1925: 363; Michener 1935: 23; Grigarick and Stange 1968: 54).

Though Grigarick and Stange (1968: 54) indicate the holotype of Dianthidium singulare var. perluteum Cockerell and Cockerell, 1904 was collected at Wilson's Peak, Strawberry Valley, California, Cockerell (1904: 23) clearly indicated that these represented two separate specimens collected at two locations in California, thus represent two syntypes.

DNA Barcode Index Number (BIN): BOLD:ADG3397

Diagnosis: Both sexes of D. singulare can be distinguished from all other Dianthidium in Canada by the large body size (> 12mm) and terga 2-5 with inflated lateral portions. In addition, both sexes possess metacoxae with a very large, elongate pale spines on outer surfaces; both sexes of D. curvatum also have spines, though these are much smaller (i.e., spine about as long as its basal width). The females can be further distinguished from other species by the combination of mandible without a distinct preapical tooth (shared only with Dianthidium plenum and D. pudicum), and apical terga and sterna with apical margins broadly truncate.

Biology: Michener (1935: 24) indicated that the nest of D. singulare perluteum consists of a single 2 by 2.5 cm cell of pebbles cemented to the face of a large boulder, the pebbles used 1 to 4 mm in diameter, and described the cocoon. Grigarick and Stange (1968: 54) provided additional details.

Distribution in Canada: Sheffield and Heron 2019 [BC].


Cresson ET (1879) Descriptions of new North American Hymenoptera in the collection of the American Entomological Society. Transactions of the American Entomological Society 7: 201-214.

Sheffield CS, Heron JM (2019) The bees of British Columbia (Hymenoptera: Apoidea, Apiformes). Journal of the Entomological Society of British Columbia 115: 44-85.

Cockerell TDA (1925) Anthidiine bees in the collection of the California Academy of Sciences. Proceedings of the California Academy of Sciences, Fourth Series 14(15): 345-367.

Michener CD (1951) Family Megachilidae. In: Muesebeck CF, Krombein KV, Townes HK (Eds) Hymenoptera of America north of Mexico Synoptic Catalog. 2. United States Department of Agriculture Agricultural Monograph, Washington. Pp. 1136-1186.

Grigarick AA, Stange LA (1968) The pollen-collecting bees of the Anthidiini of California (Hymenoptera: Megachilidae). Bulletin of the California Insect Survey 9: 1-113.

Cockerell TDA (1904) The bees of southern California. II. Bulletin of the Southern California Academy of Sciences 3: 23-24.

Timberlake PH (1943) Racial differentiation in Nearctic species of Dianthidium (Hymenoptera, Apoidea). Journal of the New York Entomological Society 51(2): 71-110.

Michener CD (1935) A note on Dianthidium singulare perluteum T. & W. Ckll. The Pan-Pacific Entomologist 11(1): 23-24.

Sociality: Solitary
Nesting: Mason
Pollen Specialization: Broad Oligolecty
Wintering Stage: Adult

Crop Preference: Not Available
Non Crop Preference: Not Available

Distribution: British Columbia
Ecozone: Western Interior Basin

Distribution Map