Corthylus microcorthyloides Atkinson, 2020

Atkinson, Thomas H., 2020, New species, new records and synonymy of Mexican Corthylus Erichson, 1834 (Coleoptera: Curculionidae: Scolytinae), Insecta Mundi 2020 (792), pp. 1-25 : 22

Corthylus microcorthyloides Atkinson , new species

Fig. 15

Diagnosis. This unusual species at first glance appears to be a species of Microcorthylus , especially because of its slender profile and the sulcate elytral declivity and small acute granules on interstriae 3. It differs from known species of that genus because the base of the pronotum has a fine raised lateral line. In most, possibly all species of Microcorthylus , the apices of the elytra are curved upwards and in direct posterior view the lower margin of the declivity is “v” shaped. In this species the apices are not upturned and the lower margin of the declivity forms a continuous curve. It could arguably be placed in that genus after revision of the character states that distinguish it from Corthylus . I have compared it to known species of Microcorthylus but it matches none of them. It would key to couplet 34 in Wood’s 1982 key to Corthylus , 53 in the 2007 key. In general appearance it most closely resembles C. convexifrons Wood.

Female. Length: 1.6 mm, maximum width: 0.9 mm; length of elytra: 0.75 mm; length to width: 2.1; elytral length/ total length: 0.56; elytral length/width: 1.20. (n = 1). Color yellowish brown, slightly darker on declivity.

Frons shining, flattened between eyes, weakly concave above epistoma to upper level of eyes; impunctate, without setae. A very faint longitudinal carina at upper level of eyes. Facets of compound eyes coarse, large in proportion to body size. Antennal club roughly oval, slightly asymmetrical. Short, erect, abundant setae distributed along entire perimeter of club, but not developed into a cirrus. Two straight sutures marked externally by shallow grooves, apparently not septate.

Anterior margin of pronotum unarmed. Anterior slope with rows of flattened asperities to summit. Disc smooth, shining, impunctate.

Elytra with discal striae and interstriae indistinct and confused at base, more distinct posteriorly with shallow punctures. Declivity abrupt in lateral profile, apex of elytra curved downwards. Interstriae 1 raised in a low costa; interstriae 2 impressed, impunctate. Interstriae 3 raised above level of 1 and 2, with 3 pointed denticles, each associated with a fine seta. Sparse, short setae also present on other posterolateral interstriae. Apical margin with a low, raised ridge, diverging from costal margin to about interstriae 7.

Male. Unknown.

Type material. Holotype: Mexico: Jalisco, Mascota, El Atajo, G.A. Quíroz R. and B.E. Díaz M., 2–31-X-2004, pitfall trap ( NTP trap) ( CNIN).

Etymology. The specific name refers to the overall appearance which resembles a species of Microcorthylus .

Figures

Figure 15. Corthylus microcorthyloides, new species, female holotype. A) Dorsal habitus. B) Lateral habitus. C) Frons and antenna. D) Declivity. All photographs by the author.