Reprinted with permission of the American Entomological Society from:
Ribble, D. W. 1974. A revision of the bees of the genus Andrena of the Western Hemisphere. Subgenus Scaphandrena. Transactions of the American Entomological Society 100: 101-189.
Please report text errors to: leah at discoverlife dot org.
Andrena capricornis hybridizes with A. scurra and A. arabis. Sec the discussion under scurra above and the next section of this paper which deals with these hybrids. Further details on the hybridization can be found in Ribble (1973). The tables and discussion in Ribble as well as the keys above can be used to separate capricornis from arabis and scurra. See Ribble also for range maps.
The descriptions below were based mainly on a female from 20 miles south of Gila Bend, Arizona and a male from Tucson.
FEMALE. — MEASUREMENTS AND RATIOS. — Length, 9.5 mm; width, 2.7 mm; wing length, 7.0 mm; FL/FW, 1.01; FOVL/FOVW, 4.89.
INTEGUMENTAL COLOR. — As in scurra except hind tibia and tarsus entirely dark.
STRUCTURE. — Antennal scape about as long as first four and one-half flagellar segments; flagellar segment 1 distinctly longer than segments 2 plus 3; otherwise as in scurra. Eyes each about four times as long as broad, inner margins nearly parallel. Mandible, stipes and galea as in scurra. Labial palpus as in scurra but ratio about 1.0:0.5:0.3:0.7. Maxillary palpus surpassing galea by last two segments, segmental ratio as 0.7:1.0:0.8:0.7:0.5:0.6. Labral process relatively large, subtrapezoidal, emarginate on side and at apex, elevated; labrum below process as in scurra. Clypeus unevenly rounded from side to side, protruding anteriorly, very shiny, center with large scattered punctures, impunctate areas, small flattened areas, shagreening very weak or absent. Supraclypeal area and face above antenna! fossae as in scurra. Facial fovea narrow, separated from lateral ocellus by about one ocellar diameter, otherwise as in scurra. Vertex above lateral ocellus about as high as slightly less than one ocellar diameter, otherwise as in scurra. Genal area as in scurra.
Pronotum. mesoscutum, scutellum, propodeum and mesepisternum as in scurra. Wings with pterostigma small, narrow, only slightly broader than from inner margin prestigma to wing margin; vein 1st m-cu meets second submarginal cell just before middle of cell; second submarginal cell medium-sized, distinctly narrowed anteriorly. Tarsal claws untoothed; hind tibia moderately widened.
Metasomal tergum 1 without apicolateral elevations, terga 2-4 with weak elevations, terga 1-4 very shiny, with small, distinct, close punctures, separated by one puncture width, shagreening absent except basally. Pygidial plate and sterna as in scurra.
VESTITURE. — Dead white, abundant. Thoracic dorsum with hairs short, erect, plumose, hiding about 75% of surface anteriorly; tibial scopal hairs long towards apex of tibia; hairs otherwise as in scurra.
MALE. — MEASUREMENTS AND RATIOS. — Length, 8.5 mm; width, 2.8 mm; wing length, 6.1 mm; FL/FW, 1.03; FS1/FS2, 2.12.
INTEGUMENTAL COLOR. — Black to dark brown with same exceptions as in female but clypeus except apex bright white, parocular area with bright white maculation reaching level of antennal fossa.
STRUCTURE. — Antenna as in scurra except: scape length about equal to first three flagellar segments; flagellar segment 1 distinctly shorter than segment 2 plus 3; segment 2 broader than long, slightly swollen. Eyes each about three times as long as broad, inner margins as in female. Mandible, stipes and galea as in scurra. Labial palpus as in female but ratio about 1.0:0.8:0.5:1.0. Maxillary palpus as in female but ratio about 0.7:1.0:1.0:0.7:0.7:1,0. Labral process moderate in size, trapezoidal, deeply notched at apex, elevated, labrum apical to process as in scurra. Clypeus evenly rounded from side to side, unshagreened. Supraclypeal area and face above antennal fossae as in scurra. Vertex above lateral ocellus about as high as one and one-third ocellar diameters, otherwise as in scurra. Genal area as in scurra.
Pronotum, mesoscutum, propodeum and mesepisternum as in scurra. Wing venation as in female. Tarsal claws as in scurra.
Terga 1-5 as in female terga 1-4 but punctures further apart, separated by about two puncture widths. Pygidial plate absent. Sterna 2-5 as in scurra but surface shinier, shagreening weak to absent. Sternum 6 as in scurra.
Terminalia as in figures 19-23; note the following: gonocoxite with dorsal lobes of moderate length, narrowly rounded, apex rather broad; penis valve with small rounded dorsal lamellae, apex short, in ventral view slightly rounded, somewhat truncate, much expanded at apex; sternum 7 with large apical notch; sternum 8 with apex slightly broader than neck region.
VESTITURE. — Generally as in female but hairs longer, notice long hairs on thoracic dorsum, moderately long hairs on tergum 1, hairs on terga 2-4 short but longer and more decumbent than in scurra; apical fasciae weakly developed on terga 2-4, broadly interrupted on center of terga 2 and 3; pollen-collecting hairs absent.
Andrena scurra X arabis X capricornis hybrids
Reprinted with permission of the American Entomological Society from:
Ribble, D. W. 1974. A revision of the bees of the genus Andrena of the Western Hemisphere. Subgenus Scaphandrena. Transactions of the American Entomological Society 100: 101-189.
Please report text errors to: leah at discoverlife dot org.
The names listed above are junior synonyms (A. arabis, capricornis and scurra are all older names) and have hybrid holotypes. The hybrids treated in this section are those specimens which are distinctly intermediate between two or all three of the parental species (arabis, capricornis and scurra). The hybrids are often very variable at a single locality or between nearby localities. It would be very difficult to use Latin names for such populations. See Ribble (1973) for further details about this hybridization in Scaphandrena and for range maps.
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