Ambrosiophilus osumiensis (Murayama, 1934)

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

Ambrosiophilus osumiensis (Murayama, 1934) Fig. 14G, H, L

Xyleborus osumiensis Murayama, 1934: 292.

Ambrosiophilus osumiensis (Murayama): Smith et al. 2018b: 393.

Xyleborus metanepotulus Eggers, 1939b: 119. Synonymy: Smith et al. 2018b: 393.

Xyleborus nodulosus Eggers, 1941b: 233. syn. nov.

Xyleborus pernodulus Schedl, 1957: 85. Unnecessary replacement name. Synonymy: Browne 1961c: 50.

Xyleborus hunanensis Browne, 1983b: 33. Synonymy: Beaver 2011: 283.

Ambrosiophilus peregrinus Smith & Cognato, 2015: 216. Synonymy: Smith et al. 2017: 552.

Type material.

Holotype Xyleborus hunanensis (IZAS). Holotype Xyleborus metanepotulus (TARI). Holotype Xyleborus nodulosus (ZMFK). Holotype Xyleborus osumiensis (NMNH). Holotype Ambrosiophilus peregrinus (NMNH), paratypes (MSUC, 5).

New records.

China: Anhui, Chuxian, 32.25N, 118.28E, 1.v.1965, Pistacia chinensis (NMNH, 4). Chongqing, Nan Shan, 20.viii.2015, Wang, J-G., Lv-Jia, Tian-Shang (RABC, 4); as previous except: Simian mtn, 7.v.2016, Tian-Shang, Lv-Jia (RABC, 2); as previous except: Youyang, 5.vi.2016, Tian-Shang (RABC, 1). Guangxi, Malu, 27.iii.2018, Y. Li, ex Cinnamomum cassia (UFFE, 1); as previous except: Shangsi, 25.iii.2018, ex Broussonetia papyrifera (UFFE, 1); as previous except: unknown host (UFFE, 1); as previous except: Shiwandashan, 25.iii.2018, Y. Li, ex Quercus griffithii (UFFE, 1); as previous except: Shangsi, 26.iii.2018, Y. Li, ex Quercus griffithii (UFFE, 1). Jiangxi, Ganzhou, Lv-Jia, ex Ligustrum lucidum (RABC, 1). Sichuan, Emei mtn, 18.viii.2016, Tian-Shang (RABC, 1). Yunnan, Xishuangbanna, Sanchahe Nat. Res., 22°09.784'N, 100°52.256'E, 2186 m, 29-30.v.2008, A.I. Cognato (MSUC, 1). Vietnam: Cao Bang, 22°34.118'N, 105°52.537'E, 1048 m, 12-17.iv.2014, VN9, Cognato, Smith, Pham, FIT (MSUC, 1). Ninh Binh, Cuc Phuong N.P., 7.iii.2018, 20.34932, 105.59669, 431 m, A.I. Cognato, S.M. Smith, VN 130, ex standing dead laurel (MSUC, 2). Thua Thien-Hue, Bach Ma N.P., 16.18902, 107.8498, 1193 m, 15.ii.2017, VN54, A.I. Cognato, T.A. Hoang, ex 1-4 cm diameter branch (MSUC, 1).

Diagnosis.

2.3-3.2 mm long (mean = 2.6 mm; n = 7); 2.3-2.67 × as long as wide. This species is distinguished by declivital interstriae 1 unarmed, 2 armed by 3-5 pointed tubercles along its length, major declivital tubercles on interstriae 2; weakly to moderately sulcate to striae 1, interstriae 2 convex, bearing 3-5 pointed tubercles and several small granules (near apical and basal margins) along its length; pronotum from dorsal view basic or subquadrate (type 2 or 3); and pronotum from lateral view basic (type 0).

Similar species.

Ambrosiophilus papilliferus , A. subnepotulus , A. wantaneeae .

Distribution.

China (Anhui, Chongqing*, Fujian, Guangxi*, Guizhou, Hunan, Jiangxi*, Sichuan*, Yunnan), Japan, Taiwan, Vietnam. Imported and established in USA ( Smith and Cognato 2015; Schiefer 2018).

Host plants.

This species is likely polyphagous and has been recorded from numerous host families including Pistacia ( Anacardiaceae ), Ilex ( Aquifoliaceae ), Quercus ( Fagaceae ), Cinnamomum ( Lauraceae ), Broussonetia (Moraceace), and Ligustrum ( Oleaceae ).

Remarks.

The morphology of A. osumiensis is highly variable in regard to numerous characteristics that are routinely used to diagnose other xyleborine species. Such variation includes: the antennal club type either 3 or 4; pronotum basic (type 2) or subquadrate (type 3) from dorsal view; declivity shiny or shagreened; pronotal disc shiny or shagreened; number and size of tubercles on declivital interstriae 2; and a large size range with individuals differing by up to 0.9 mm in length. This variation led to A. osumiensis being described several times. Types of each species are distinct and diagnosable. Examination of the specimens listed above in 'new records’ as well as the holotypes showed that these species formed a continuous spectrum of variation. During our fieldwork we were able to collect and sequence specimens that fell within the concept of X. metanepotulus (Vietnam), X. hunanensis (China), X. nodulosus (China) and A. peregrinus (Georgia, USA) and an additional larger morphospecies from multiple localities in Vietnam. COI sequences showed that all populations differed by no more than 7.4% supporting the hypothesis of one morphologically variable species. Typical intraspecific variation in xyleborines is below 10% ( Cognato et al. 2020b). Xyleborus hunanensis , X. metanepotulus , X. nodulosus and A. peregrinus are thus all conspecific and considered synonyms of the oldest name, A. osumiensis .

The identification of A. nodulosus from East Malaysia by Browne (1980b) and Ohno (1990) appears to be incorrect. We have therefore omitted East Malaysia from the distribution, and also omitted the associated host records. The host records reported in Smith et al. (2017) are therefore incorrect.

Figures

Figure 14. Dorsal, lateral and declivital view of Ambrosiophilus indicus holotype, 2.4 mm (A, B, I), A. lannaensis holotype holotype, 1.95 - 2.05 mm (C, D, J), A. latisulcatus, 3.9 - 4.2 mm (E, F, K), and A. osumiensis, 2.3 - 3.2 mm (G, H, L).