Memoirs on the coleoptera

CERAMBYCID/E 365
and there are enough special features, generally asexual in other
parts of the genus, such as the form of the prothorax,
to show
that the female type described really represents a species distinct
from any of the others; they all seem to be rather rare and seldom
taken in series. The general characters of the group are a mixture
of those of the undulatus and nauticus groups, with some, such
as thoracic form and elytral ornamentation, that are essentially
peculiar.
The females of the insignis group resemble Clytus, as represented
by planifrons for example, much more closely in form and ornamentation
than they do any of the other types of the genus Xylo-
trechus; the males differ greatly from the females in being very
pale red-brown in color, with more suffused vestiture and indis-
tinct or partially obsolete fasciee, which are so well developed in
the female. So, although the species of this group are truly Xylo-
trechus, as shown by the peculiar sexual modifications of the head,
consisting of two large, very finely sculptured triangular opaque
patches on the vertex of the male, which are completely obsolete
on the more coarsely sculptured vertex of the female, and, as shown
by the frontal carinae, they nevertheless constitute a remarkably dis-
tinct and aberrant group of the genus in the sexual diversity referred
to above, which is analogous to that even more developed in the
genus Calloides. The species of this group in my collection may
be defined as follows:
Elytra with the curved transverse fascia before the middle in the female
equal and entire, mounting more narrowly along the suture to a
point some distance behind the scutellum, sometimes altogether
wanting and always greatly reduced in the male 2
Elytra as in the preceding, except that the fascia before the middle in
the female ends just outside of the median line, the continuation
2
indicated by a small elongate spot near the margin
Elytral
4
fasciae in the female white in color and all rather narrow;
frontal carinse fused into a tumid oblong punctate glabrous spot;
annuli of dense hairs at the apices of all the abdominal segments
narrow and white; body black in color throughout, the legs and
antennae testaceous. Length (9) 14.5 mm.; width 4.7 mm.
Colorado obliteratus Lee.
Elytral fasciae in the female bright sulphur-yellow in color and much
3
broader.
Form more elongate than in the preceding, larger
3
in size, the female
black, with the elytra blackish-brown, the legs and antennae rufous;
frontal carinse only feebly marked, the intermediate surface flat,