Checklist of the suborder Terebrantia (Thysanoptera): generic diversity and species composition in Xishuangbanna, Yunnan Province, China

Abstract Background Thysanoptera is amongst the most predominant orders of insects in different ecological zones with worldwide distribution. Due to their small size, there is a large gap in their distribution and host range data. To the best of our knowledge, there is no investigation on the thrips distribution and their host range in Xishuangbanna. Currently, a total of 566 species in 155 genera are listed in China, of which 313 species represent Terebrantia. New information In this study, a list of 116 species representing 55 genera within the families Aeolothripidae and Thripidae is provided. Two of these, Dichromomothripsnakahari Moud, 1976 (subfamily Thripinae) and Phibalothripsrugosus Kudo, 1979 (subfamily Panchaetothripinae) are recorded for the first time in China. Thrips species with their host ranges, habits and habitats are provided. Our study aims to contribute to the global biodiversity distribution data-gap of Thysanoptera for conservation purposes, as well as pest species targetting Integrated Pest Management tactics.


Introduction
Thysanoptera (commonly known as thrips) is a group of small insects with body length ranging from 0.5 to 5.0 mm (except for a few tropical species, which may reach 14 mm). They are characterised by piercing-sucking with the distinction of only one completed left mandible (Hunter and Ullman 1992). Thrips exhibit high potential of sexual or parthenogenetic reproduction with rapid growth (Ramakrishna andMargabandhu 1931, Ananthakrishnan 1969) and dwell in a great diversity of habitats. More than 50% are mycophagous with the remaining phytophagous and predators. Besides, a few species have been recorded to annoy or bite people and cause non-severe skin irritation (Borror 1998).
The world updated checklist of Thysanoptera is totalling about 6,337 extant species representing 786 genera (ThripsWiki 2020). In China, the basic taxonomic work on Thysanoptera comprises two checklists Tong 1993, Mirab-balou et al. 2011), of which about 100 species representing 40 genera were individually studied from Xishuangbanna. However, there is no checklist of Thysanoptera diversity and species composition have been conducted in Xishuangbanna which is the home of a unique evergreen Tropical Rainforest and Botanical Garden and the most biodiversity-rich place in Yunnan Province, harbouring much of the biodiversity of China (Liu et al. 2015). This study aims to investigate the diversity of suborder Terebrantia (Thysanoptera) and its hosts which are important for developing of sustainable biodiversity, conservation and Integrated Pest Management (IPM).

Permanent slides preparation
Adult thrips were mounted according to the standard slides preparation techniques ) and identified following the standard identification keys provided by Mound and Marullo (1996), Masumoto and Okajima (2006) and . Morphological characters were observed under a compound microscope Olympus BX 41. Photos of species were taken with a CCD Zeiss Microscope. Species distribution used thrips distribution information available (ThripsWiki 2020) and the Zoological Catalogue of Smithers et al. (1997).
Permanent slides were labelled with the site, host plant, date of sampling and collector's name (left side); specimen ID, genus, species, sex and identified author's name (right side). All slides were grouped by genus-species in boxes labelled with YAU5082020 (representing institutional code), Tt ((T) representing Thysanoptera and (t) Terebrantia in collection code), No. of slide ID Material is deposited in the Insect Taxonomy laboratory, Plant Protection College at Yunnan Agricultural University, Kunming, China. Some information on individual species was collected from previously-studied references.
Feeds on: leaves and collected from grasses. Feeds on: leaves and collected from Pueraria lobata and Ficus tree.
Distribution: Described from Japan. Recorded from China (Li et al. 2021). Male of Astrothrips asiaticus (Bhatti, 1967  Female of Copidothrips octarticulatus (Schmutz, 1913). Diagnosis: Female macropterous; body bicoloured ( Fig. 10), head and thorax dark brown and constricted behind eye, abdomen yellow; legs and antennal segments III-V yellow; fore wing slender, uniformly pale or a little darker at base, with no long setae; antennae 6-segmented, V-VII form single unit; sensoria on III and IV slender, each with one simple sensorium. Male similar to female, but smaller, without pore plate at Female of Phibalothrips rugosus Kudo, 1979. sternites III-VII. The distinctive feature of this genus is an elongated head that is strongly irregular, circular reticulated and constricted behind the eyes. Diagnosis: Female macropterous, body brown to paler (Fig. 14); head wider than long, weakly reticulated with broad reticulate posterior collar; ocellar setae I present, II longer than III; three pairs of well-developed postocular setae; maxillary palps 2-segmented; antennae 8-segmented, segment I without paired dorso-apical setae; III with sense cone forked, IV with one forked and one simple sense cones. Pronotal with or without Figure 13.
Feeds on: leaves and collected from Moraceae.

Subfamily Dendrothripinae
Dendrothrips minowai Priesner, 1935 Diagnosis: Female fully winged, body bicoloured (Fig. 15); head brown laterally and at anterior, white medially; antennal segments I-IV brown, V-IX paler, VI with sense cone on basal half; pronotum shaded on lateral margins, with two longitudinal brown markings laterally; abdominal tergites paler; fore wing brown and all legs paler.

Material
Feeds on: flowers, collected from Erythrina variegata L., Psidium guava and mango.
Distribution: Described from Japan and widely distributed. Diagnosis: The female fully-winged; body mainly paler with brown markings (Fig. 19), head wider than long, constricted just behind compound eyes paler with shaded cheeks; antennal segments I and III yellowish-white, II and VI to VIII brown, IV yellowish-white with distal half brown, segment V yellowish-white with distal third brown; pronotum yellowish-white with two submarginal longitudinal brown bands; fore wings with alternate four white areas and three brown bands; abdominal terga II to VII sculptured. Male generally similar to female, but slightly smaller, sternites III-VIII with scattered small pore plates. Diagnosis: Female macropterous; body and legs yellow (Fig. 20), head and pronotum with dark lateral margin, antennal segments I-II brown, III-V yellow with the apex brown, VI-VII brown, VIII pale brown; fore wing brown with apex pale, clavus brown; abdominal tergites with transverse striae laterally, tergites II-VII with three setae arranged in a straight line. Male generally similar in structure and colour similar to female, sternites without pore plates.   Diagnosis: Trichromothrips trifasciatus differs from other species of the same genus by fore wing base not shaded along the anterior margin, basal half of antennal segments III-V yellow and abdominal tergites with some light brown patches (Fig. 21).

Megalurothrips typicus
Feeds on: leaves and collected from potato leaves.  Female of Trichromothrips trifasciatus Priesner, 1936. for others (fungi, rocks and mosses). Fabaceae, Poaceae and Asteraceae showed a high population, whereas Bryophytes (mosses) and Pteridophyta (ferns) showed the low population dynamics of thrips species.

Thysanoptera (suborder Terebrantia): species composition and distribution
A total of 116 species in 55 genera within the families Aeolothripidae and Thripidae were recorded. Thripidae is represented with 115 species, whereas Aelothripidae is represented with a single species. The genus Thrips is represented with 11 species and Trichromothrips with 10 species, both being the most commonly encountered taxa. Dichromomothrips nakahari Mound, 1976 (subfamily Thripinae) and Phibalothrips rugosus Kudo, 1979 (subfamily Panchaetothripinae) are newly recorded in China. A distribution map (Fig. 22) of Terebrantian (Thysanoptera) in Xishuangbanna is provided with supplementary material for details (Suppl. material 1).

Discussion
In this study, we found that Xishuangbanna shows the high thrips species composition with asymmetric geographical distribution as demonstrated in the world distribution of Thysanoptera (Mound and Marullo 1998) and (Mound 1983). Recorded species are representing 40.3% of the 313 species of the Terebrantian (Thysanoptera) in China. In addition, this place is the home of some rare genera and species, such as Araliacothrips Li, Li & Zhang, Filicopsothrips pulcher Li, Yuan & Zhang, Amomothrips Bhatti and different predatory species of the family Aeolothripidae. Dichromomothrips nakahari Mound, 1976 (subfamily Thripinae), described from Indonesia (Mound 1976) and Phibalothrips rugosus Kudo, 1979 (subfamily Panchaetothripinae), described from Kuala Lumpur, Malaysia (ThripsWiki 2020), are newly-recorded species in Chinese fauna. Our results suggest that Xishuangbanna is the richest area in Thysanoptera species composition to be taken into consideration for biodiversity conservation. However, some species from the references were lacking sufficient information for the records and deposition to be the common challenge in the taxonomic study (Kuznetsova and Ivanova 2020) and suggest that detailed inventories on the specimens records and modernised open, readily accessible online or digitised data are required for sustainable taxonomic studies, as suggested by Specht et al. (2018). Besides, further investigations are suggested to explore the species diversity and variation within Thysanoptera ecosystem services provided in this area for sustainable biodiversity conservation.