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Reprinted with permission from: Daly, H. V. 1973. Bees of the genus Ceratina in America North of Mexico (Hymenoptera: Apoidea). University of California Publications in Entomology 74: 1-114. The Regents of the University of California. Published by the University of California Press.
Ceratina pacifica H. S. Smith, 1907
Female.—Measurements and ratios: wing, 6.25 mm; hamuli, 7; eye, 130:150:153:158; clypeus, 71 × 138:46:107; interocellar, 31:54:46:71, Ø 17.8; frontal carina, 69; malar area 0 × 56; interalveolar, 38:36:51:59, Ø 17.8; antenna, 71:18:18:10:10:13, Ø 15.3; subpleural signum, 20 × 3.8 (California, Los Angeles Co., Crystal Lake in San Gabriel Mtns., C. subpunctigena paratype; C.I.S.).
Structure: Head rounded in cephalic view; eyes subparallel; narrowly rounded above, sub- truncate at malar area; frontal carina simple, sulciform beneath median ocellus; supraclypeal, interalveolar, and alveolocellar areas gently convex; vertex and supraorbital areas limited by preoccipital carina; median portion of hypostomal carina when viewed laterally of uniform height and right-angled at anterior termination, when viewed ventrally angle between median and lateral portions about 110° - Basitibial plate acute, its elevated apex at basal 0.22 of tibial length. Metasoma widest at segment 4; gradulus of tergum 4 terminating laterally beyond and below spiracle; tergum 5 with median central protuberance, producing subapical notch in profile; graduli of sterna 2—3 transverse, straight.
Sculpture and vestiture: Head shiny between punctures, largely impunctate on mandible base, clypeal disc, lower supraclypeal area, lower paraocular area, subantennal area, alveolocellar area and laterally in narrow band which extends posteriorly around eye; elsewhere with fine punctures more than a puncture width apart and largely simple setae; punctures closer in interalveolar gad alveolorbital areas, laterally on supraorbital area, and postgena; setae longer in interalveolar area, vertex, postgena, labral disc, and apically on mandible. Sides of pronotum moderately punctured less than a puncture width apart and often contiguous, impunctate area before pronotal pit; scutal disc shiny, virtually impunctate except along lines, fine punctures marginally and as close as a puncture width apart laterally and on axilla; scutellar disc sparsely and finely punctured, punctures closer and less than a puncture width apart laterally and posteriorly; metanotum finely punctured throughout less than a puncture width apart; mesopleuron with coarse punctures less than a puncture width apart laterally, becoming more widely spaced posteroventrally, setae narrowly plumose, becoming longer posteroventrally; hypoepimeral area impunctate in lower third; metapleuron finely punctured about a puncture width apart, impunctate before metapleural pit; propodeal triangle of about 20 longitudinal carinulae, with some anastomosis and becoming indistinct laterally; the angle impunctate, minutely coriaceous; sides finely punctured, becoming much closer and much smaller laterad, with long erect narrowly plumose setae. Metasomal tergum 1 finely punctured on dorsal surface, several puncture widths apart, virtually impunctate on anterior surface; terga 2—5 with scattered fine punctures on pregradular area near gradulus; postgradular punctures fine and several puncture widths apart centrally, coarser and closer laterad, each bearing a short appressed simple seta, ground shiny, but subapically papillate especially on tergum 5, tergum 6 finely and closely punctured less than a puncture width apart, ground papillated basally and rugulose apically; setae short, simple, except on central protuberance which bears long plumose setae. Sterna finely punctured, about a puncture width apart, setae simple, coarse, suberect, dense at abdominal apex; setae of wax glands appressed.
Color: Body metallic blackish blue (ISCC-NBS 188) with minor yellowish reflections on mesoscutum; metallic colors lacking on labrum, mandibles, mesoscutal disc, and wax glands. Ivory marks: amygdaliform on clypeus, but reduced to 0.3 length of clypeus; spots at bases of all tibiae, being largest on metatibia; pronotal lobes. Antennae fuscous, lighter beneath; legs proximally fuscous, femora and tibiae faintly metallic, tarsi apically testaceous; tegula and wing membrane testaceous, venation darker. Body setae pale flavescent.
Male.—Measurements and ratios: wing, 4.7 mm; hamuli, 6; eye, 108:110:100:95; clypeus, 50 × 90:30:80; interocellar, 22:35:25:50, Ø 16.0; frontal carina, 60; malar area, 0 × 40; interalveolar, 20:22:40:42, Ø 18; antenna, 35:15:15:10:10:15, Ø 15; subpleural signum, 15 × 4.0. (Idyllwild, San Jacinto Mts., California; California Insect Survey)
Structure: Head rounded in cephalic view; eyes convergent below, narrowly rounded above, broadly rounded at malar area; frontal carina simple, distinct between alveolae, sulciform beneath median ocellus; vertex and supraorbital area limited posteriorly by preoccipital ridge with low carina; median portion of hypostomal carina when viewed laterally of low uniform height, terminating anteriorly without a tooth, when viewed ventrally lateral portion arcuate. Ventral profile of metatrochanter rounded, apical anteroventral facet obscure, polished and with fine punctures; width of metafemur at tooth 0.4 length, tooth with obtuse 130° angle, basal facet directed ventrad, distinct, polished slightly concave surface, ventral edge with medium, sparse, narrowly plumose setae (resembles fig. 10a). Metasoma widest at segment 4; gradulus of tergum 4 terminating laterally beyond and below spiracle at a distance of 2.0 spiracle lengths; tergum 6 without median subapical protuberance (resembles fig. 11o); dorsal view of apical plate width 2.0 times length; sternum 6 with one median tooth (resembles fig. 13h). Genitalia presumed to be similar to fig. 29c.
Sculpture and vestiture: Head shiny between punctures, largely impunctate on clypeal disc, lowest parocular area, subantennal area, most of convex portion of alveolocellar area and in narrow band behind eye; sparse punctures on mandible base with minute and fine punctures; gena with medium punctures about a puncture width apart; elsewhere with fine to medium punctures about a puncture width apart and with largely simple setae; punctures closer in interalveolar area, sparser in ocellorbital area; sparse setae longer in interalveolar and postgenal areas, vertex, labral disc, and posteriorly on mandible. Sides of pronotum finely punctured, less than a puncture width apart, impunctate area above pronotal pit extending to beneath dorsolateral angle; scutal disc shiny, moderately punctate along lines, fine punctures marginally and contiguous laterally and on axilla; scutellar disc moderately punctate, fine punctures becoming less than a puncture width apart laterally and posteriorly; metanotum finely and almost contiguously punctured throughout; mesopleuron with coarse punctures less than a puncture width apart laterally, becoming more widely spaced posteroventrally, long plumose setae; hypoepimeral area impunctate in lower third; metapleuron finely punctured, usually about a puncture width apart; small impunctate area before metapleural pit; propodeal triangle reticulate rugulose, 2—3 longitudinal carinulae distinct medially; angle of propodeum impunctate, minutely coriaceous; sides finely punctured, becoming contiguous and smaller laterad, with erect, plumose setae. Metasomal tergum 1 finely punctured on dorsal surface several puncture widths apart, virtually impunctate on anterior surface; terga 2—6 with moderately dense fine punctures on postgradular area near gradulus, postgradular punctures line and uniformly slightly more than a puncture width apart, each with a short appressed simple seta; ground shiny, but minutely roughened on terga 5—6; tergum 7 finely punctured slightly more than a puncture width apart with shiny ground, apical plate above with long, spreading plumose hairs extending beyond plate. Sterna 1—5 medium punctured, about a puncture width apart; setae fine, suberect, narrowly plumose, longer subapically on each sternum.
Color: Read and thorn metallic very dark greenish blue (ISCO-NES 175); abdomen more bluish but cuticle beneath metallic reflections dark fusco-rufous; metallic colors lacking on mandibles which are dark fusco-rufous. Ivory marks: irregular hat-shaped on clypeus, extending 0.6 length and full width; small irregular spot on labral disc; spots at bases of all tibiae, being largest on metatibia; pronotal lobes. Antennae blackish, lighter beneath; legs proximally dark fusco-rufous, femora and tibiae faintly metallic, tarsi apically dark testaceous; wing membrane testaceous, venation and tegula dark testaceous. Body setae pale flavescent.
Male compared with illustrations of other specimens: metafemur and metatrochanter (fig. l0a), sternum 6 and apical plate (fig. 13k); genitalia not dissected, but illustrated from another specimen (fig. 29c).
Ceratina pacifica is a widespread, medium-sized bee in the western United States (fig. 24). It is easily recognized as one of two species in North America in which the females possess a hair tuft on a central protuberance of the sixth metasomal tergum. Throughout the Great Basin this character will separate U. pacifica from the other common medium-sized bee, C. neomexicana. In cismontane California, C. punctigena also has a similar hair tuft, but it is distinguished by a genal spine. The males may be differentiated from C. neomexicana by the shiny, ventral facet on the metafemur in contrast to the dull, sparsely punctured, poorly defined facet in C. neomexicana. In cismontane California, the closely related C. punctigena has the femoral facet flat, shiny and oriented more anteriorly.
Variability in size is sufficiently great as to render meaningless a single sample statistic for the species and considerably larger numbers from throughout the range will be required for an adequate analysis. Specimens from cismontane California were distinguished by Michener as C. sub punctigena and from Utah as U. utahensis. These segregates are considered here as members of a single, highly polytypic species. The females from cismontane California are visibly larger in size (female wing lengths range 4.5—6.3 mm) and have a reduced clypeal mark or none. Collections are mainly from Chaparral, Mixed conifer, and California oakwoods (fig. 5a) - In transmontane California (Lone Pine, Westgard Pass, Antelope Springs), the females average much smaller (4.7—5.6 mm) and have a broad, well-defined clypeal mark. The clypeal mark is also frequently present in specimens from British Columbia, Colorado, Nevada, and Oregon and the sizes are variable, but intermediate between the two distinctive California segregates. In Idaho and Utah, the sizes are again large, ranging in female wing lengths 4.4—6.3 mm and the clypeal maculation i5 frequently reduced or entirely absent. Outside of cismontane California, the bees are most frequently collected in Sagebrush steppe, Juniper-pinyon woodland, Great Basin sagebrush, and Mountain mahogany-oak scrub vegetation types.
In cismontane California, the placement of the eggs on the pollen loaves, nest size, and nest substrates are similar to C. punctigena, but rarely encountered at the same site with that species (figs. 31g, 3lm).
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