Yaobinthrips yangtzei

Xie, Yong-Hui & Zhang, Hongrui, 2016, First description of the male of Yaobinthrips yangtzei (Thysanoptera: Thripidae), Zootaxa 4066 (1), pp. 83-84 : 83-84

First description of the male of Yaobinthrips yangtzei ( Thysanoptera : Thripidae )

YAJIN L I 1,2,YONG-HUI XIE3 & HONGRUI ZHANG1,2

1 Ministry of Education Key Laboratory of Agriculture Biodiversity and Pest Management, Kunming, 650201 2 Plant Protection College, Yunnan Agricultural University, Kunming, 650201 Corresponding Author E-mail: [e-mail] 3Kunming Tobacco Company, Kunming, 650051, P.R. China

The monobasic Thripinae genus Yaobinthrips has been known only from females, and the objective here is to provide a description of the male. A member of the Frankliniella genus-group, the type species, yangtzei Zhang et al. (2010) was described from specimens taken in Sichuan Province of Southwestern China from the flowers of Dalbergia yunnanensis [ Fabaceae ]. In April, 2015 a sample of both sexes of this thrips species was taken from the white flowers of the same plant species, but in Yunnan Province. This plant is actually widespread in southwestern China in Yunnan, Sichuan, Guizhou Provinces and Guangxi Zhuang Autonomous Region. Provinces, growing at an elevation ranging from 1400 to 2200 meters, and flowering from April to May ( Li et al. 2007).

Description. Male macroptera. Body smaller and more slender than female; colour similar to female. Body dark brown; all tarsi yellow, also fore tibia except at base; antennal segments III–IV and basal half of V yellow; fore wing including clavus brown, with apex pale, and sub-basal area posterior to vein also pale ( Fig. 1 ). Antennae 8-segmented, segment I without dorso-apical setae, III–IV with sensoria forked, VIII longer than VII ( Fig. 2 ). Head wider than long, sculpture distinctly striate behind eyes; postocular setae I just behind ocellar setae III ( Fig. 4 ). Pronotum with no sculpture except for three transverse lines near posterior, discal setae minute, three pairs of posteromaginal setae; inner posteroangular setae longer than outer pair. Metanotum reticulate, CPS present, median setae situated at anterior margin. Fore wing first vein with distal four setae wider apart than their length. Fore femora very slightly swollen, inner margin very slightly depressed medially; fore tibiae with only one short, broadly rounded bulbous modified seta ( Fig. 8 ). Abdominal sternites III–VII each with a large transverse pore plate ( Fig. 6 ); tergite IX with two pairs of stout thorn-like setae developed in two rows between the pair of CPS, anterior pair longer than second pair; pleurotergites IX & X each with one pair of stout thorn-like setae ( Fig. 11 ).

Measurements (male in microns). Body length 1086. Head, length 79; width 134; distance between compound eyes 62. Fore wing length 609. Antenna length 217; segments I–VIII length 22, 29, 29, 31, 22, 39, 10, 16.

Material studied. CHINA, Yunnan Province, Wuding County, Jiyi Valley (26°05'53"N, 102°15'37"E), 19 females, 15 males from white flowers of Dalbergia yunnanensis at 1540 m, 23.iv.2015 (Zhang Hong-rui, Li Ya-jin), in collection of Yunnan Agricultural University, Kunming.

Remarks. Both sexes exhibit confusing variation in structure. In males, the two pairs of stout setae medially on tergite IX are much smaller in one available male ( Fig. 13 ), and in another the number is reduced to three arranged in a triangle ( Fig. 12 ). In one male the pore plate on sternite IV is divided into two ( Fig. 7 ), in contrast to the normal condition in the other males, and one male lacks a bulbous seta on both fore tibiae whereas in another male such a seta is present only on one of the fore tibiae. Females in this species are unusual in having a pair of small circular pore plates on sternite VI, but these are not developed in one available female. Moreover, the number of pronotal posteromarginal setae varies from three to four, the number of marginal setae on the fore wing clavus from five to six, and the number of bulbous setae on the fore tibiae from one to four although it is usually two( Figs. 8–10 ). Similarly confusing is variation in the precise position of postocular setae pair I and ocellar setae pair III ( Figs. 4, 5 ).

Amongst the single series of specimens listed above, two individuals exhibited a curious coincidence of antennal abnormality, such that segment III is unusually small with only seven segments developed, in contrast to the normal condition ( Figs. 2, 3 ). This abnormality was noted in the left antenna of one female, and in the right antenna of one male. Field populations of thrips species are usually bisexual, with females often predominant. In some cosmopolitan species, the sex ratio differs in different regions, possibly dependent on temperature with fewer males occurring where it is warmer ( Lewis 1973). In this connection, the original specimens of yangtzei were all females and were collected in Sichuan Province at 1881m, where the temperature was 20–35ºC. In contrast, the specimens reported here from Yunnan Province, with a sex ratio of 1.3:1, were collected at 1540 m, where the temperature was 10–25ºC.

Figures

FIGURES 1 – 13 Yaobinthrips yangtzei (1) Male. (2) Antenna 8 - segmented. (3) Antenna 7 - segmented. (4) Normal ocellar setae. (5) Abnormal ocellar setae. (6) Male sternites III – VII. (7) Male sternite IV abnormal. (8) Male fore tibia. (9 – 10) Female fore tibiae. (11 – 13) Male tergites IX – X.