Weevils - Entomological Society of Canada

This genus contains four species in North America (Hamilton 1985;
O'Brien and Wibmer 1982). Two of them, M. bicolor (Fabricius) and
M. wickhctmi (Cockerell), have been consistently confused in the North
American literature, being regarded either as synonyms or as separate
species by various authors. Hamilton (1985) revised the genus,
characterized each species, and designated a number of subspecies.
Subspecies are not used in the following treatment because I do not
agree with Hamilton's (1985) interpretation. In my view, subspecies are
geographically defined segregates of a population. Only one subspecies
can exist in a breeding condition in any one area. In Hamilton's analysis,
several subspecies of both M. bicolor and M. wickhami coexist in one
area.
Description. Body moderate in size (up to 8.2 mm); integument
varying from completely black to red on dorsal surfaces and black on
head and ventrally. Pubescence inconspicuous, the setae abundant, fine,
erect, hair-like. Head conical, narrowed toward rostrum, widest at base;
surface dull or shining, moderately densely punctured. Rostrum
straight, slightly widened at apex. Antennae (Fig. 156) inserted midway
between eye and apex of rostrum. Pronotum as wide as or slightly wider
than long, narrower than elytral bases, weakly constricted anteriorly;
disc moderately punctured. Elytra stout, robust, wider than pronotum;
striae moderately to weakly impressed in distinct to indistinct rows,
with round impressed punctures; interstriae varying from smooth to
densely and minutely rugose. Pygidium visible, vertical, convex. Tarsi
with claws deeply cleft; inner teeth connate. Procoxae in males with
round to oval and densely setose pits on apex.
Type species. Curculio bicolor Fabricius, by subsequent
designation.
Key to species ol Merhynchites in Canada
1. Eyes, in dorsal view, strongly convex, forming almost 907o angle
with rostrum at anterior margin of eye (Fig. 9, l-60). Rostrum of
both sexes more or less straight, more so in females (Figs. 158, 159).
Elytra with striae moderately impressed; interstriae smooth.
Ontario to British Columbia . bicolor (Fabricius) (p. 157)
Eyes, in dorsal view, very weakly convex, forming 45Vo angle with
rostrum at anterior margin of eye (Fig. 165). Rostrum of female
slightly, evenly arcuate; rostrum of male obviously arcuate beyond
antennal insertions (Figs. 163, 164). Elytra with striae weakly
impressed, indistinct; interstriae minutely rugose. Alberta, British
11-l1i' *:::T::i T:::i*:: :' :?:k*#y ?t ".r..,.ri i rp i a o r
156