Batley & Houston: Australian bee genus Trichocolletes 
33 
T. maximus T. brachytomus n.sp. T. pulcherrimus T. dives 
Figs 20-23. Basal area of hind tibia of Trichocolletes females: (20) T. maximus, (21) T. brachytomus n.sp., (22) T. pulcherrimus, and 
(23) T. dives. Setae were removed from the T. maximus and T. brachytomus n.sp. specimens, but shortened by wear in the other cases. 
trochanters and basal half of femora dark brown. Tl-4 with 
moderately wide, white bands distinctly ferruginous across 
anterior margins; wings darkened.— Surface of clypeus 
polished with very broad irregular depressions, dulled basally 
with pit-reticulation; labrum with longitudinal medial carina 
and weak, oblique rugae laterally.— Apico-lateral comers 
of clypeus, paraocular areas and frons densely covered with 
golden-brown, plumose hair. Scutum closely covered with 
densely-branched, pale orange-brown hair tipped with dark 
brown; prepygidial fimbria chocolate brown; hind tibial 
scopa pale orange. 
Remarks. This species is referred to as F265/M236 in 
Houston (2000). 
Distribution. Geraldton Sandplains, Western Australia (GS) 
(Fig. 110). 
Etymology. The specific name is from the Greek adjective 
for flat-faced, referring to the clypeus, particularly of the 
female. 
Trichocolletes pulcherrimus Michener 
Figs 9, 22, 26, 111 
Trichocolletes (Callocolletes) pulcherrimus Michener, 1965, p. 265. 
Specimens examined. Holotype $, Narrogin, Western Australia, 1 
Nov. 1935, WAM (65-727) and the following. Western Australia: 
Dumbleyung, 14 Nov. 1966, H. Udell, WAM (9007); 4$, 75 km E Hyden, 
24-27 Oct. 1985, T. F. Houston, on flowers of Gastrolobium spinosum, 
WAM (8997-9000); 2$, 61 km E Hyden, 14 Oct. 1979, T. F. Houston, on 
flowers of Burtonia hendersoni, WAM (9001-02); Regans Ford Moore 
River, 11 Nov. 1976, S. M. Postmus, on Jacksonia sp., WAM (9006); 
10 S Perenjori, 1 Nov. 1958, E. F. Riek, ANIC; 3$, 19 km ESE Southern 
Cross, 28 Oct. 1978, T. F. Houston, on flowers of Gompholobium viscidulum, 
WAM (9003-05). 
Diagnosis 
Length 16-18 mm; eyes not hairy; metasoma orange- 
brown with indistinct metasomal bands; flagellum banded 
dorsally in both sexes. Male hind tibia strongly expanded, 
without spurs; apical segment of flagellum truncate, slightly 
expanded on one side; fore trochanter with large spine. 
Female scape and more than half clypeus orange-brown. 
Remarks. Detailed descriptions can be found in Michener, 
1965. 
In 1965, Michener proposed division of the genus 
Trichocolletes into two subgenera, with this species as the 
sole member of the subgenus Callocolletes. At that time, 
the Colletidae family was regarded as a primitive lineage, 
but molecular evidence now indicates that it is one of the 
more derived (Danforth et al., 2006) and that separation 
of Trichocolletes from other Australian colletids occurred 
relatively early (Almeida and Danforth, 2009). However, 
the premise on which the subgenus was based remains 
unaltered. If the hind basitibial area of T. pulcherrimus 
females is intermediate in nature between those found in 
the remaining Trichocolletes species and those of other 
colletids, it might indicate that T. pulcherrimus occupies a 
basal position within the genus. 
The use of molecular evidence from fresh material to 
test this hypothesis was, unfortunately, not possible as 
attempts to recollect specimens were unsuccessful, but the 
increased number of species now available made possible 
reassessment of the morphological evidence. Although the 
male exhibits a number of striking modifications including 
the absence of hind tibial spurs, Michener (1965, 2007) 
chose to give greater weight to the hind basitibial area and 
details of wing venation. 
The basitibial area of females is difficult to observe 
because of a dense cover of stiff setae. When the setae are 
removed, the contiguous depressions at the base of each seta 
form a coarsely areolate surface (Fig. 22). Interpretation 
of the resulting structure can be difficult. Frequently 
specimens are found with the setae worn down to the tops 
of the depressions making the actual surface difficult to 
detect and producing an apparent rim to the basitibial area. 
A second difficulty is that even when setae are removed 
cleanly, the edge of the basitibial area may be coarsely 
serrated where it intersects the depressions (as shown for 
T. brachytomus n.sp. in Fig. 21). It is unclear whether or 
not this state should be classified as carinate. 
A better character to use may be the hind basitibial area 
of males. Comparison of the basitibial areas of males of 
eight species with those of conspecific females confirmed 
that the degree of elevation of the basal area from the 
surrounding surface of the tibia in males reflected that 
observed for the females after removal of the setae. Of the 
