Reprinted from: Snelling, R. 1970. STUDIES ON NORTH AMERICAN BEES OF THE GENUS
HYLAEUS. 5. THE SUBGENERA HYLAEUS. S. STR. AND
PARAPROSOPIS (HYMENOPTERA: COLLETIDAE) Contributions in Science, No. 180.
The status of this form. described from a single male from Georgia. is
enigmatical. It is known only from the unique type, which I have not examined.
Metz (1911) considered it a synonym of H. cressoni, but Mitchell
(1960) has elevated it to species level and briefly redescribed the type. Unfortunately,
Mitchell's description contributes nothing new to permit the
recognition of H. labiatifrons. In all features it seems to agree quite closely
with males of H. cressoni cressoni, and seems to differ from that species only
in the entirely yellow tibiae.
This difference seems to me to be of little value. Another Nearctic
Hylaeus, H. illinoisensis (Robertson). is supposedly recognizable on the same
basis. In that species. at least, males with entirely yellow tibiae are exceptional.
Even those which have the tibiae wholly yellow show, under intense light, a
slightly darker basal two-thirds which corresponds to the black basal area of
most specimens. I suspect that the same is true in the case of H. labiatifrons,
which I regard as a probable synonym of H. cressoni cressoni. The solution
must wait until the type, especially ventrites eight and nine, can be examined
and compared with those of the related species.
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