Bombus caliginosus ( Frison, 1927 )

Bombus caliginosus ( Frison, 1927) View in CoL , nomen protectum

Bombus flavifrons Smith, 1866 View in CoL , in Lord, 1866: 343 (appendix) [ ♀]. Preoccupied, not Bombus flavifrons Cresson, 1863 View in CoL . Neotype: ♀ (designated here; Fig. 1 View Figure 1 ). Canada, British Columbia, Vancouver Island, Victoria [Island] , Butchart Gardens , 30 May 1973, by S. Gittelman [American Museum of Natural History, no. AMNH_BEE 00120464 ] .

Bombus columbicus Dalla Torre, 1890: 139. Replacement name for Bombus flavifrons Smith, 1866. Nomen oblitum. View in CoL

Bremus caliginosus Frison, 1927: 376 [ ♂]. Syn. nov. Holotype: ♂. USA, California, Arcata, 16 September 1920, by C. D. Duncan [Illinois Natural History Survey, no. 179514]. View in CoL

Bremus caliginosus var. tardus Frison, 1927: 380 [ ♂]. Synonymy of Bremus caliginosus Frison, 1927 by Stephen (1957: 100). Holotype: ♂. USA, California, Carmel, 20 July 1921, by L. S. Slevin [California Academy of Sciences no. 2438]. View in CoL

Remark.

The original description of Bombus flavifrons Smith was of a female with a body length of 8 ½ lines (ca 18 mm), consistent with the neotype selected here (Fig. 1 View Figure 1 ).

Diagnosis.

Females of B. caliginosus have a longer malar space (length: width = 0.90, Fig. 2 a View Figure 2 ) than those of B. vosnesenskii (length: width = 0.71, Fig. 2 b View Figure 2 ) and in many specimens sternum 4 of the former has a weak apical (posterior) band of pale hairs, at least laterally ( Thorp et al. 1983; Williams et al. 2014) (Fig. 1 d View Figure 1 ), though as cautioned by Williams et al. (2014) this is also true for some specimens of B. vosnesenskii . Williams et al. (2014) also noted that tergum 4 of B. caliginosus often has some dark hairs basally, especially medially, while in B. vosnesenskii the black hairs are lacking, or few. Stephen (1957) noted that the relative lengths of flagellomeres 1 and 3 also differed, flagellomere 1 longer than 3 (3: 2) in B. caliginosus , but the lengths are subequal in B. vosnesenskii . Williams et al. (2014) made note of the size differences of punctures on the apical margin of the clypeus, being small in B. caliginosus , but large in B. vosnesenskii .

Males of the two species can be also distinguished by the relative lengths of flagellomeres 1 and 3, the lengths being subequal in B. caliginosus , but flagellomere 1 shorter than 3 in B. vosnesenskii ( Stephen 1957; Thorp et al. 1983). The males also differ in the shape of the apical recurved portion of the penis-valve head, narrowing apically in B. vosnesenskii , but remaining subparallel in B. caliginosus ( Stephen 1957; Williams et al. 2014). Thorp et al. (1983) also provided illustrations noting differences in the shapes of sterna 7 and 8, the latter gradually narrowing apically (i. e., triangular) in B. caliginosus (their fig. 63), while widely truncate apically in B. vosnesenskii , with the lateral margins subparallel to base of process (their fig. 72).