Cyclorhipidion distinguendum (Eggers, 1930)

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

Cyclorhipidion distinguendum (Eggers, 1930) Fig. 41E, F, K

Xyleborus distinguendus Eggers, 1930: 205.

Cyclorhipidion distinguendum (Eggers): Maiti and Saha 2004: 105.

Xyleborus fukiensis Eggers, 1941b: 225. syn. nov.

Xyleborus ganshoensis Murayama, 1952: 16. syn. nov.

Type material.

Neotype Xyleborus distinguendus (FRI). Holotype Xyleborus fukiensis (ZMFK). Holotype Xyleborus ganshoensis (NMNH).

New records.

China: Beijing, 15.iv.1980, Peiyu Yu (NMNH, 1). Fujian, Chong’an, Guidun, 1500 m, 7.v.1978, ex Cyclobalanopsis glauca [= Quercus glauca ] (NMNH, 2). Hong Kong, Tai Po Kau, vi.2017, J. Skelton, ex Castanopsis (MSUC, 2). Jiangxi, Long Nan, 12.vii.2016, Lv-Jia, Lai, S-C., ex Cyclobalanopsis glauca (RABC, 1). Yunnan, Xishuangbanna, Sanchahe Nat. Res., 22°09.784'N, 100°52.256'E, 2186 m, 29.v.2008, A.I. Cognato (MSUC, 4); S Yunnan, Xishuangbanna, 23 km NW Jinghong, vic. Na Ban village (NNNR), 22°10'N, 100°39'E, 700-1000 m, v-vii.2009, L. Meng (NKME, 1). Japan: Tsukuba, 27.viii.1980, S.L. Wood, ex Abies firma (NMNH, 1). Taiwan: Fushan, iii.2015, J. Hulcr, ex Pasania [= Lithocarpus ] (UFFE, 1). Taichung, Heping Dist., 29.iv.2014, C.-S. Lin (MSUC, 1). Tai Pei Co., Noi Dong logging road, 850 m, 19.ii.2004, Chun Lin Li, ex flight intercept trap (MFNB, 1). Vietnam: Cao Bang, 22°34.5'N, 105°52.4'E, ~ 1080 m, VN 20, Cognato, Smith, Pham, ex branches (MSUC, 4). Lao Cai, Hoang Lien N.P., 22.35, 103.77, 1500 m, 17.v.2019, VN161, S.M. Smith, A.I. Cognato, ex branch; 5 cm (MSUC, 1). Thua Thien-Hue, Bach Ma N.P., 16.19718, 107.86002, 1409 m, 14.ii.2017, VN50, A.I. Cognato, T.A. Hoang, ex Fagaceae , 4 cm branch and twigs (MSUC, 2).

Diagnosis.

2.5-3.11 mm long (mean = 2.78 mm; n = 15); 2.6-3.0 × as long as wide. This species is distinguished by the short, steep declivity that is approximately 25% of total elytral length, armed with large tubercles on interstriae 1 and 3, interstriae 2 always unarmed; posterolateral margins rounded; and declivital interstriae 1 setae in three confused rows and interstriae 2 setae in two confused rows (Table 1 ). This species is highly morphologically variable. See remarks below.

Similar species.

This species is a part of a challenging species group consisting of C. bodoanum , C. inarmatum , C. pelliculosum , C. tenuigraphum and C. xeniolum (Table 1 ).

Distribution.

China (Beijing*, Fujian, Hong Kong*, Jiangxi*, Yunnan*), India (Uttarakhand), Japan, Nepal, South Korea, Taiwan, Thailand, Vietnam*. Recently established in the United States ( Hoebeke et al. 2018) and France ( Dodelin 2018) as C. fukiense .

Host plants.

Recorded from Castanea , Lithocarpus , and Quercus ( Fagaceae ), and probably with a close association with Fagaceae ( Beaver et al. 2014).

Remarks.

Images of the X. distinguendus holotype were examined and compared to the X. fukiensis and X. ganshoensis holotypes and were found to be conspecific. Both X. fukiensis and X. ganshoensis are here placed in synonymy.

The declivity of C. distinguendum is highly morphologically variable in regard to numerous key features that are routinely used to diagnose other xyleborine species and each elytron of an individual often has a different arrangement of tubercles. When trying to identify C. distinguendum note that the characters listed above in the diagnosis are the only way to reliably identify the species. Characters such as surface luster, the number, size, and position of interstrial tubercles, declivital puncture size, interstrial convexity and strial impression are all highly variable. Variation in all these characters can be found in individuals from one locality and even from a single host (Smith, pers. obs.). Individuals exhibiting such variation were monophyletic in a molecular phylogeny using COI and CAD ( Cognato et al. 2020b). Examples of variation in the declivity include: A. The declivital surface shiny, opalescent or shagreened; B. Strial and interstrial puncture size range from equal widths to those of the striae 2 × as large as those of interstriae; C. Interstriae 2 flat to depressed (typically depressed); D. Interstriae 1 and 3 flat to convex (typically convex); E. Interstriae 1 tuberculate with 1-3 tubercles and granules varying in both number and position; F. Interstriae 3 with 2-5 tubercles and often granules, all of which vary in position. G. Surface slightly to deeply impressed between striae 1 and 2.

Figures

Figure 41. Dorsal, lateral and declivital view of Cyclorhipidion circumcisum, 3.3 - 3.5 mm (A, B, I), C. denticauda holotype, 2.95 - 3.1 mm (C, D, J), C. distinguendum, 2.5 - 3.1 mm (E, F, K), and C. fouqueti lectotype, 1.8 mm (G, H, L).