Xylosandrus crassiusculus (Motschulsky, 1866)

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

Xylosandrus crassiusculus (Motschulsky, 1866) Fig. 93G, H, L

Phloeotrogus crassiusculus Motschulsky, 1866: 403.

Xylosandrus crassiusculus (Motschulsky): Wood 1977: 68.

Xyleborus semiopacus Eichhoff, 1878b: 334. Synonymy: Wood 1969: 119.

Xyleborus semigranosus Blandford, 1896b: 211. Synonymy: Schedl 1959: 496.

Dryocoetes bengalensis Stebbing, 1908: 12. Synonymy: Beeson 1915: 297.

Xyleborus mascarenus Hagedorn, 1908: 379. Synonymy: Eggers 1923: 130.

Xyleborus ebriosus Niisima, 1909: 154. Synonymy: Choo 1983: 98.

Xyleborus okoumeensis Schedl, 1935b: 271. Synonymy: Schedl 1959: 496.

Xyleborus declivigranulatus Schedl, 1936d: 30. Synonymy: Schedl 1959: 496.

Type material.

Holotype Xyleborus semigranosus (NHMUK).

New records.

China: Chongqing, Peng Shui, 10.v.2015, Tian-Shang, ex Castanea molissima (RABC, 1); as previous except: Nan Chang, Jiangxi Agric. Univ. orchard, v.2015, Su, T-L., ex Choerospondias axillaris (RABC, 1); as previous except: Pengshui, 11.viii.2016, Tian-Shang (RABC, 3). Jiangsu, Nanjing, Laoshan National Park, Bacai Road, 32.09156; 118.583701, 15.viii.2017, Cognato, Li, Gao, ex Populus (MSUC, 2). Shanghai, Dongchuan, vii-viii.2017, Gao, ex trap w/ querciverol (MSUC, 4). India: Arunachal Pradesh, Etalin vicinity, 28°36'56"N, 95°53'21"E, 700 m, 12-25.v.2012, L. Dembický (ZFMK, 3). Vietnam: Cao Bang, 22°34.532'N, 105°52.480'E, 1087 m, 11.iv.2014, VN6, Cognato, Smith, Pham, ex 2 cm diameter branches, pithy, soft wood (MSUC, 1). Dong Nai, Cat Tien N.P., 11.43771, 107.42253, 142 m, 21.ii.2017, VN86, A.I. Cognato, T.A. Hoang, ex 5 cm diameter branch (MSUC, 3). Ha Tay, Ba Vi N.P. (lake lodge), 196 m, 3-4.vii.2008, J.B. Heppner (FSCA, 1). Kon Tum, Ngoc Linh, 2 km S., 15°5'18"N, 107°55'42"E, 1070 m, 7-12.ix.1998, B. Hubley, D.C. Currie, VIET1H95-99 046, ex malaise trap (SEMC, 1). NE region, Lang Son, Mau Son Nat. Park, 13-14.vi.2016, at lights, 21°51.001'N, 106°55.074'E, G.S. Powell (MSUC, 1). Thua Thien-Hue, Bach Ma N.P., 16.22897, 107.85349, 415 m, 15.ii.2017, VN57, A.I. Cognato, T.A. Hoang, ex 5 cm diameter branch; twig (MSUC, 9). Tuyen Quang, Doi Can Tuyen Quang, 21.72740, 105.22742, 15.iv.2015, R.J. Rabaglia, ex funnel trap (RJRC, 2). Yen Bai, Mau A’, 21.88226, 104.68040, 15.iv.2015, R.J. Rabaglia, ex funnel trap (RJRC, 1); as previous except: Tan Huong, 21.82410, 104.89651 (RJRC, 1).

Diagnosis.

2.3-2.9 mm long (mean = 2.58 mm; n = 5); 2.17-2.42 × as long as wide. This species is distinguished by the moderate to large size; elytral disc gradually curving toward declivity, elytra rounded; posterolateral margins of elytra carinate to interstriae 7; declivital face with six striae; interstriae and striae granulate, confused, appearing dull, with erect hair-like setae longer than the width of two interstriae; pronotum as long as wide, pronotum from dorsal view rounded (type 1) and lateral view basic (type 0), summit at midpoint, basal 1/2 smooth, shiny, sparsely minutely punctate; and dense mycangial tuft on the pronotal base.

Similar species.

None.

Distribution.

In temperate and tropical regions around the world. Within the study region recorded from Bhutan, Cambodia, China (Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Hong Kong, Hubei, Hunan, Jiangsu*, Jiangxi, Shaanxi, Shandong, Shanghai*, Sichuan, Xizang, Yunnan, Zhejiang), India (Andaman Is, Arunachal Pradesh*, Assam, Himachal Pradesh, Karnataka, Meghalaya, Sikkim, Tamil Nadu, Uttarakhand, West Bengal), Laos, Myanmar, Nepal, Taiwan, Thailand, Vietnam. Also present in South & North Korea. Imported to and established in Europe, North, Central and South America ( Kirkendall and Ødegaard 2007; Pennacchio et al. 2003; Flechtmann and Atkinson 2016; Landi et al. 2016; Gallego et al. 2017; Gomez et al. 2018a).

Host plants.

Strongly polyphagous ( Dole and Cognato 2010).

Remarks.

The basic biology has been described by Browne (1961a), Schedl (1963a) (both as Xyleborus semiopacus ), and Ranger et al. (2016) amongst others. Flight activity, and the attraction of flying adults to ethanol has been studied in the southern USA by Reding et al. (2011, 2013), attack densities and adult emergence on various hosts by Mayfield et al. (2013), and attraction to volatiles from the symbiotic ambrosia fungus by Hulcr et al. (2011). This is a species of economic importance because, like X. compactus , it can attack and breed in healthy shoots and twigs. This can result in the introduction of pathogenic fungi ( Sreedharan et al. 1991; Davis and Dute 1997). It seems to be an infrequent pest in the Oriental and Afrotropical regions, although attacks on transplants have been recorded (e.g., Browne 1968a). It is of greater importance in USA, where its ecology and management in plant nurseries is discussed by Ranger et al. (2016).

Figures

Figure 93. Dorsal, lateral and declivital view of Xylosandrus borealis, 2.0 - 2.2 mm (A, B, I), X. brevis, 2.75 - 2.9 mm (C, D, J), X. compactus, 1.5 - 1.9 mm (E, F, K), and X. crassiusculus, 2.3 - 2.9 mm (G, H, L).