Corthylus cristatus 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 : 6-9

Corthylus cristatus Atkinson , new species

Fig. 4 A, B ; Fig. 5 A–D

Diagnosis. This species, C. cristatulus , new species, and C. granulocristatus , new species, are quite similar in general appearance ( Fig. 4 ). They can be distinguished from each other by body size, size and density of punctures on the declivity, and by variations in the size of the elevated, serrate crest on the declivity. This crest is the sharply elevated third interstriae. This crest is strongly curved towards the median line in the middle of the declivity, strongly reducing the width of interstriae 1 and 2, but in “normal” position at the base and apex of the declivity. The posterolateral area of the declivity is strongly elevated (couplet 1, Wood 1982). The combination of the curved, serrate declivital crest, elevated posterolateral line on the declivity which is otherwise convex, and the deep confused punctures on the elytra are unique to this group among the known species of the genus. Corthylus cristatus is distinguished from the other two by the closely spaced, large confused punctures on the elytral disc, separated by their own diameter. The declivital crest on interstriae 3 is the most pronounced in height and curvature to the point that interstriae 2 are basically obsolete in the middle of the declivity.

Female. Length: 3.12 mm (2.97–3.33), maximum width: 1.23 mm (1.13–1.27); length of elytra: 1.23 mm (1.67–1.90); length to width: 2.5; elytral length/total length: 0.58; elytral length/width: 1.47. (n = 4, 3 males, 1 female). Color uniformly black.

Frons evenly concave from epistoma to vertex. Lower surface with widely spaced, low granules, each associated with a short seta. Setae becoming denser on sides and upper portion of frons, marginal setae only slightly longer than those in center, not forming incurved margins. Area just above epistoma impunctate. Antenna slightly asymmetrical, 1 st and 2 nd sutures indicated by external grooves, 1 st partly septate. Cirrus very short, longest setae less than 1/2 the width of the antennal club.

Anterior margin of pronotum broadly rounded, unarmed. Asperities on anterior slope not elevated, weakly developed, obsolete at summit. Pronotal disc shining, with deep punctures, separated by about 3× their diameters.

Striae and interstriae indistinct on elytral disc, all punctures similar in size and completely confused, those at base of elytral about twice as large as punctures on pronotal disc and separated by about twice their diameters. Declivity abruptly curved in profile. Elevated postero-lateral crest at elytral apex weakly developed, partly obscured by deep confused punctures. Striae and interstriae indistinct on declivity, but short, yellow setae present on odd-numbered interstriae. Interstriae 1 slightly costate, without or with very weakly developed granules. Interstriae 2 impressed, extremely narrow in declivital face. Interstriae 3 strongly elevated, with contiguous, pointed granules, giving a serrate impression, strongly curving towards declivital suture in middle, curving outwards again towards apex, serrate elevation not reaching bottom 1/3 of declivity. Much smaller granules irregularly spaced exterior to interstriae 3.

Male. Similar to female except for frons and antenna. Frons evenly convex, shining, with widely separated, deep punctures, vestiture absent. A weak transverse impression above epistoma. Antenna suboval, without longer, marginal setae.

Type material. Holotype female. Mexico: Veracruz, El Santuario , campus INECOL, 28-III-2016, bottle trap with ethanol, L.A. Ibarra and A. Gil V. ( CNIN) . Allotype male. Veracruz, El Santuario , campus INECOL, 9-V- 2016, bottle trap with ethanol, A. Gil V. ( CNIN) ; Paratypes. Veracruz, El Santuario , campus INECOL, 3-II-2016, bottle trap with ethanol, L.A. Ibarra and A. Gil V. ( IEXA, 1m, UTIC, 1m) ; Chiapas: Chiapas, Union Juarez ; 15.1597°N, 92.17°E; IV-2013, cloud forest with pines and coffee; Francisco Infante , UFFE:11049 ( UFFE, 2 f in ethanol) ; Guatemala: El Progreso, 29 km N. San Augustín, 21-IV- 1990, 650 m, J.E. Wappes ( TAMU, 1 m) .

Comments. The anterior portion of pronotum in the female holotype in Fig. 5 is abnormal, whether from damage to the specimen or abnormal development.

Etymology. The name is chosen for the prominent curved crest on the elytral declivity.

Figures

Figure 4. Species of Corthylus with acute spines on declivity or with interstriae 3 curved and serrate (2 of 2). A, B) C. cristatus new species, holotype. C, D) C. cristatulus new species, holotype. E, F) C. granulocristatus new species, holotype. G, H) C. poblanus new species, holotype. All photographs by the author.

Figure 5. Corthylus cristatus, new species, female holotype. A) Dorsal habitus. B) Lateral habitus. C) Frons and antenna. D) Declivity. Note: anterior portion of pronotum is abnormal, whether from damage to the specimen or abnormal development. All photographs by the author.