Extracted from: Grigarick A.A., & Stange L.A., (1968). The Pollen Collecting Bees of the Anthidiini of California (Hymenoptera: Megachilidae) Bulletin of the California Insect Survey Volume 9.
Heteranthidium timberlakei Schwarz, 1928. Jour. New York
Ent Soo, 36:409-412, $, 9. Holotype d\ Riverside,
California (UCR). Heteranthidium subtimberlakei Schwarz, 1928. Jour. New
York Ent Soc., 36:414-415. Holotype 9, Nevada Co.,
Heteranthidium zebratum timberlakei Schwarz. Michener, 1951, U.S.D.A. Agric. Mono. No. 2, p. 1138.
Heteranthidium zebratum subtimberlakei Schwarz. Michener 1951, U.S.D.A. Agric. Mono. No. 2, p. 1138.
Heteranthidium zebratum zebratum, Stephen and Torchio (not Cresson), 1961 Pan-Pac. Ent, 37(l):41-43.
Geographic range.—California, western Nevada, Oregon.
California records.—EL DORADO Co.: Bass Lake, 2 $, VI-10-37 (B. White, CAS). Kyburz, 1 9, IX-1-63 (UCD). Meyers, 2 mi. S, 1 6\ V1I-24-55 (E. Schlinger, UCD).
FRESNO CO.: Pinehurst, 2 mi. E, 9 $, VI-24-60, on Cirsium (R. Snelling, SS). Tollhouse, 1.5 mi. NW, 1 9, VI-20-63, on Clarkia cylindrica (J. Chemsak, CIS). INYO Co.: Panamint Mt, Wild Rose Cn., 1 $, 1 9, VI-19-37, on Chaenactis Douglasii (C. Michener, UCR). Los ANGELES Co.: Big Dalton Dam, 1 9, VI-25-50 (J. MacSwain, CIS). MADERA CO.: Bass Lake, 1 <$, VI-7-38 (N. Hardman, CIS). Nipinnawasee, 1 $, V-24-36 (E. Ross, CAS). MARIPOSA CO.: Mariposa Co., 1 9, VI-13^38 (N. Hardman, CIS). Bagby, 4.2 mi. N, 1 6\ VI-19-63, (J. Chemsak, CIS); 2 9, on Clarkia biloba (R. Thorp, CIS). MONO CO.: Mammoth, 1 9, VII-8-38 (R. 8B G. Bohart, CIS). NAPA CO.: Rutherford, 14 mi. E, V-23-65, 5 6\ on Cirsium; 3 9, on Clarkia gracilis, V-26-65, 1 $, 5 9, on Clarkia gracilis, 7 6\ 5 9, (R. Thorp, RT). NEVADA CO.: Nevada Co., 1 9 (Hort Com., UCR). RIVERSIDE CO.: The Gavilan, 1 $, V-31-37, 1 9, VI-9-56, on Helianthus graci-lentus (P. Timberlake, UCR). Herkey Creek, San Jacinto Mts., 1 9, VI-10-40, sweeping (CIS). Keen Camp, 8 mi. W. San Jacinto Mts., 1 $, V—16-39, on Cirsium (E. Linsley, CIS). Pifion Flat, San Jacinto Mts., 1 $, V-21-39, on Encelia (E. Linsley, CIS); 1 6\ VI-21-41 (E. Van Dyke, CAS). Riverside, 1 9, IV-28-28, on Chaenactis glabriuscula; 1 $, IV-30-28, 2 S, V-3 8s 5-28, on Encelia farinosa, 1 3» V-25-32, on Coreopsis lanceolata (P. Timberlake, UCR); 2 9, VI-19-33 (C. Dammers, UCR). San Jacinto River, 2 6\ V-30-40, on Compositae (LACM). Santa Rosa Mt, 8,000, 1 9, VI-20--40 (E. Van Dyke, CAS). SAN BENITO CO.: Idria, 14 6\ 4 9, VI-14 to 15-55 (D. Burdick, C MacNeill, M. Wasbauer, CIS); 2 $, 1 9, VI-15-55, on Cirsium (D. Burdick, CIS). Pinnacles, 16\ V-2S-A1 (CIS); 3 6\ V-28 to 29-60 (D. Rentz, SS). SAN BERNARDINO CO.: Cajon Pass,
3 8, 1 9, VI-24-41 (E. Van Dyke, CAS). Phelan, 1 8, VI-27-52 (Beamer, Liang, LaBerge, SS); 2 mi. W, 1 8, VI-7-58 (J. Hall, UCD). SAN DIEGO CO.: Coronado, 1 8, V-5-40 (F. Blaisdell, CAS). ML Laguna, 1 8, VII-5-63 (J. Powell, CIS). Warner Springs, 1 8, VI-10-56 (E. Schlinger, UCD). SAN LUIS OBISPO CO.: Santa Margarita, 5 mi. NE, 1 5, VI-15-63, on Clarkia cylinqdrica (R. Thorp, CIS). SANTA BARBARA CO.: Figueroa Mtn., 1 8,1 9, IV-7-39 (C. Norland, LACM). Sunset Valley, 2 8, VII-4-38 (B. White, CAS). SANTA CLARA CO.: San Antonio Valley, 2 8, VI-13-50 (W. Barr, UI). TRINITY CO.: Carrville, 10 mi. N, 1 9, VII-15-55 (J. Jessen, UCD). Coffee Creek Ranger Station, 10 mi. N, 1 9, VII-14-55 (J. Wells, UCD). TULARE CO.: Kings Canyon National Park, 5,000 feet, 1 8, VI-21-60 (G. Fuller-ton, SS). YOLO CO.: Rumsey, 4 mi. NE, 1 8, VI-3-60 (R. Schuster, UCD). Winters, 1 8, VI-10-50 (J. Gillaspy, CIS).
Heteranthidium timberlakei is closely related to H. autumnale and H. zebratum. H. zebratum is widely distributed east of the Rocky Mountains, and several workers have considered timberlakei a subspecies of zebratum. Snelling reelevated timberlakei to the species level and discussed this group in 1966. The males of timberlakei are most readily separated from those of zebratum by having the apical margin of tergum VII uniformly convex (fig. 123) except for the extension of the median carina, whereas tergum VII of zebratum is prominently trilobed. The emargination of sternum V of the male of timberlakei (fig. 127) contains a posteriorly directed projection, but this emargination is simple in autumnale (fig. 128) and zebratum. A carina is present on the antero-dorsal edge of the pronotal lobe of all three species but it is produced into a lamellate margin on autumnale.
The males of timberlakei have cream facial markings and the remainder of the maculations of the male and all of those of the female are yellow on black. Considerable variation has been observed in the extent of maculations of timberlakei with the trend toward reduction with an increase in latitude. The species H. subtimberlakei falls about midway within the range of this variation, and there appears to be little value in retaining this name. Specimens of timberlakei are generally considerably larger than larreae and bequaerti, although this is also subject to variation.
H. timberlakei is infrequently collected in long series and only 76 males and 35 females have been examined. It is widespread in the foothills of major mountain ranges of California and has also been observed from western Nevada and southern Oregon.