Metachroma pallidum (Say 1824)

Metachroma pallidum (Say)

Colaspis pallida Say, 1823, p. 446.

Colaspis dubiosa Say, 1823, p. 447.

Metachroma dubiosum (Say).—Horn, 1892, pp. 212, 213.

DESCRIPTION.—Say’s description of Colaspis pallida is as follows:

Pale rufous, elytra pale testaceous, immaculate. Inhabits Missouri. Body very pale rufous; head obsoletely punctured, an indented abbreviated line or spot on vertex; thorax with puntures small, sometimes obsolete; elytra pale testaceous with striae of punctures which become obsolete before the tip. Beneath pale. L. 3/20 of an inch. Very similar to C. notata but is always destitute of spots on the elytra.

His description of Colaspis dubiosa is as follows:

Pale rufous, elytra testaceous with a black suture dilated at base. Inhabits Arkansa. This species seems to differ from the preceding only by having a black suture dilated at base, a black lateral edge on the anterior half, sometimes obsolete, and a black basal ventral segment; the thorax is sometimes obsoletely dotted with black, and in one specimen is a small black spot anterior to the middle of each elytron; 6-notata, 4-notata, pallida, and dubiosa may possibly prove to be the same species exhibiting remarkably distinct variations in the distribution of its colours. Found near the Rocky Mts. I think it possible that dubiosa may prove to be a variety of Cryptocephalus canellus Fabr.

In the LeConte collection the label on the first specimen of a series of beetles (apparently all the same species) is M. pallida dubiosa (Say), which would seem to indicate that LeConte regarded dubiosa as only a color form of M. pallidum. There are eleven specimens following the one bearing the label, which is an entirely pale yellow-brown beetle with a light green disc label. There are five specimens with green disc labels (indicating Kansas, Nebraska, etc.) five specimens with light blue labels (Lake Superior), and one specimen with a pink label (Middle States). In the second specimen the elytra have a piceous sutural darkening such as Say described in dubiosa. The third specimen, like the first, has the elytra entirely pale yellow-brown. The fourth specimen has a thorax with a dark spot on either side and the elytra with a dark sutural vitta. The remaining specimens have the sutural darkening varying in width and the prothorax varying from having dark spots to being entirely piceous. The sculpture is similar in all the specimens. The head is nearly impunctate, yellow-brown with dark brown jaws; there is no transverse sulcus dividing front from clypeus, but there is a small median frontal depression in some specimens; the interocular space is about half width of head. The thorax is moderately convex with rounded sides, very finely and sparsely punctate; the elytra have fine striate punctures fading at apex but well-marked on the sides. The body beneath, legs, and antennae are all pale. Femora not toothed, claws with long tooth. Length, 3.8–4.4 mm; width, 1.9–2.2 mm.

DISTRIBUTION.—Kansas: Sheridan County, at 2,500 feet, S. J. Hunter; Stafford County, D. B. Lindsay; Garden City, H. W. Menke; Decatur County, at 2,560 feet, S. J. Hunter; Hamilton County, F. H. Snow; Clark County, F. H. Snow. Arkansas. Nebraska: Superior. Dakota. Kentucky: Benton, R. H. Beamer; Tennessee: Burrville, B. Benish. Illinois: Valmeyer, M. W. Sanderson.

Metachroma pallidum is a species of leaf beetle. It is found in the United States.