Microperus minax, Smith & Beaver & Cognato, 2020

Smith, Sarah M., Beaver, Roger A. & Cognato, Anthony I., 2020, A monograph of the Xyleborini (Coleoptera, Curculionidae, Scolytinae) of the Indochinese Peninsula (except Malaysia) and China, ZooKeys 983, pp. 1-442 : 1

Microperus minax sp. nov. Fig. 68C, D, J

Type material.

Holotype, female, Vietnam: Ninh Binh, Cuc Phuong N.P., 20.33296, 105.61259, 7.iii.2018, 279 m, A.I. Cognato, S.M. Smith, VN 141, ex 6 cm diameter branch (MSUC). Paratypes, female, Vietnam: Ninh Binh, Cuc Phuong N.P., 20.34932, 105.59669, 431 m, 5.iii.2018, A.I. Cognato, S.M. Smith, VN 113b, ex Terminalia myriocarpa; large tree-fall trunk, 8 cm (NMNH, 1); Thua Thien-Hue, Bach Ma N.P., 16.19831, 107.85639, 1386 m, 17-18.ii.2017, VN69, A.I. Cognato, T.A. Hoang, ex 6 cm diameter branch (MSUC, 1).

Diagnosis.

1.95-2.0 mm long (mean = 1.98 mm; n = 2); 2.79-2.86 × as long as wide. This species is distinguished by the declivital interstriae densely covered with long erect hair-like setae; elytral disc medially convex, appearing humped; declivity long, gradual; all declivital interstriae uniformly granulate from base to apex; declivital face convex; posterolateral carina granulate; antennal club truncate, type 2 with one suture visible on posterior face near apex; and declivity smooth, shiny.

This species is nearly identical to M. intermedius (Eggers, 1923) which has not been reported from the study region. Microperus minax is distinguished by the larger size (1.6-1.8 mm in M. intermedius ) and the elytral disc longer, occupying 36-42% of total elytral length (30% in M. intermedius ).

Similar species.

Microperus diversicolor , M. kadoyamaensis .

Description

(female). 1.95-2.0 mm long (mean = 1.98 mm; n = 2); 2.79-2.86 × as long as wide. Body dark red-brown. Legs and antennae light brown. Head: epistoma entire, transverse, with a row of hair-like setae. Frons weakly convex to upper level of eyes, subshiny, punctate, punctures small, shallow, moderately dense, glabrous; a few punctures in lateral areas bearing a long, erect hair-like seta. Eyes shallowly emarginate just above antennal insertion, upper part smaller than lower part. Submentum narrowly triangular, slightly impressed. Antennal scape short and thick, shorter than club. Pedicel as wide as scape, shorter than funicle. Funicle 4-segmented, segment 1 shorter than pedicel. Club longer than wide, obliquely truncate, type 2; segment 1 corneous, transverse on anterior face, occupying basal 2/5, nearly covering posterior face; segment 2 narrow, corneous; segment 1 present on posterior face. Pronotum: 1.0 × as long as wide. Basic and parallel-sided, type 2 in dorsal view, sides parallel in basal 2/3, rounded anteriorly; anterior margin without serrations. In lateral view elongate with disc slightly longer than anterior slope, type 7, disc flat, summit at apical 2/5. Anterior slope with densely spaced, broad asperities, becoming lower and more strongly transverse towards summit. Disc shagreened, alutaceous, impunctate, glabrous, some moderately long hair-like setae at margins. Lateral margins obliquely costate. Base transverse, posterior angles acutely rounded, almost subquadrate. Elytra: 1.7 × as long as wide, 1.7 × as long as pronotum. Scutellum minute, convex, slightly raised above elytral surface. Elytral mycangium present as a dispersed median setal tuft of setae extending along elytral base to striae 3. Elytral base transverse, edge oblique, humeral angles rounded, parallel-sided in basal 9/10, then narrowly rounded to apex. Disc medially convex, appearing humped, shiny, striae not impressed, with small shallow punctures separated by 1-2 diameters of a puncture, setose, setae short, semi-erect, hair-like; interstriae flat, minutely punctate, setose, setae 2 × as long as strial setae, erect, hair-like. Declivity occupying over 1/2 of elytral length, long, gradually rounded, face convex, shiny; striae flat, setose, setae as described for disc, impunctate; interstriae 1-3 parallel, interstriae densely covered with long, erect hair-like setae; all interstriae densely and uniformly granulate from base to apex, densely setose, setae as described for disc. Posterolateral margin carinate, granulate to interstriae 7. Legs: procoxae contiguous; prosternal coxal piece tall, pointed. Protibiae slender, broadest at apical 1/3; posterior face smooth; apical 1/3 of outer margin with seven moderate socketed denticles, their length approximately as long as basal width. Meso- and metatibiae flattened; outer margin evenly rounded with 13 and 11 socketed denticles, respectively; basal two denticles longer than basal width, much larger than other denticles, remaining apical denticles very small, their length much shorter than basal width.

Etymology.

L. minax = threatening. In reference to the species habit of using live trees to host brood chambers. An invariable adjective.

Distribution.

Vietnam.

Host plants.

This species was collected from Terminalia myriocarpa ( Combretaceae ).

Remarks.

Microperus minax was collected from apparently healthy branches of living trees (SMS, AIC, personal observation) and may be an aggressive species.

Figures

Figure 68. Dorsal, lateral and declivital view of Microperus latesalebrinus holotype, 1.6 mm (A, B, I), M. minax holotype, 1.95 - 2.0 mm (C, D, J), M. nudibrevis, 1.5 - 1.6 mm (E, F, K), and M. nugax, 1.8 - 1.9 mm (G, H, L).