Xyleborinus subgranulatus (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

Xyleborinus subgranulatus (Eggers, 1930) Fig. 86C, D, J

Xyleborus subgranulatus Eggers, 1930: 202.

Xyleborinus subgranulatus (Eggers): Wood and Bright 1992: 817.

Type material.

Holotype (FRI), paratype (NMNH).

New records.

China: Yunnan, Gaoligong Mts., 25.22N, 98.49E, 1500-2500 m, 17-24.v.1995, V. Kubáň (NKME, 1); S Yunnan, Xishuangbanna, 29 km NW Jinghong, vic. Da Nuo You NNNR, 22°12.41'N, 100°38.29'E, 790 m, fallow GF, 23.v.2008, A. Weigel (RABC, 1); as previous except: 37 km NW Jinghong, vic. Guo Men Shan, 22°14.48'N, 100°36.22'E, 1080 m, forest, EKL, 16.iii.2009, L. Meng (NKME, 1). Laos: NE, Houa Phan, Phou Pane mt., 20°13'09-19"N, 103°59'54"-104°00'03"E, 1480-1510 m, 22.iv-14.v.2008, V. Kubáň (MNHP, 1). Taiwan: Yilan co., Fushan, v.2009, ex sticky trap (RABC, 1). Vietnam: Cao Bang, 22°34.118'N, 105°52.537'E, 1048 m, 12.iv.2014, VN13, Cognato, Smith, Pham, ex large felled Pinus sp. (MSUC, 1). Vinh Phuc, Tam Dao, 6-9.v.1990, P. Pachlolátko (RABC, 1). Tuyen Quang, 3 km SE Pac Ban village, Na Hang Nature Reserve, 22.20; 105.25, 380 m, at light, 22-26.ii.1997, G. Csorba (HNHM, 1).

Diagnosis.

1.6-1.8 mm long (mean = 1.7 mm; n = 5); 3.0-3.4 × as long as wide. This species is distinguished by the declivital face with interstriae 2 armed by granules at declivital summit, unarmed on declivital face; declivital interstriae 1 and 3 denticles subacutely pointed; denticles on ventrolateral areas of the elytra small, less acute; declivital interstriae 2 slightly impressed; discal interstriae 1 and 2 granulate, granules extending from declivital summit to mid-point of disc; and minute size.

Similar species.

Xyleborinus attenuatus , X. saxesenii , X. subspinosus , X. thaiphami .

Distribution.

China* (Yunnan), India (Assam, West Bengal), Laos*, Taiwan*, Thailand, Vietnam*,

Host plants.

Recorded from four genera in four different families ( Maiti and Saha 2004) as well as Pinus ( Pinaceae ) and is presumably polyphagous.

Remarks.

This species is strikingly similar to, and has been recovered as, sister to Xyleborinus saxesenii using COI data ( Cognato et al. 2020b) but the elytral morphology is inconsistent within single specimens. Given its close relationship with X. saxesenii the species is expected to have denticles along declivital interstriae 1 and 3. However this is not always the case and the species can also have declivital interstriae 1 and 2 unarmed with denticles along interstriae 3. Both tubercle patterns have been found on each elytron of single individuals, including the paratype examined and individuals from a series collected in [West] Bengal.

Figures

Figure 86. Dorsal, lateral and declivital view of Xyleborinus spinipennis, 2.3 - 2.75 mm (A, B, I), X. subgranulatus, 1.6 - 1.8 mm (C, D, J), X. subspinosus holotype, 2.3 mm (E, F, K), and X. thaiphami holotype, 2.8 - 2.9 mm (G, H, L).