Mesandrothrips inquilinus Priesner

Mesandrothrips inquilinus Priesner View in CoL

( Figs 61 View FIGURES 57–69 , 94–101 View FIGURES 94–101 )

Haplothrips inquilinus Priesner, 1921: 4 View in CoL .

This species was originally described from Java, Indonesia, under the genus Haplothrips View in CoL , and known as an invader of galls of several phlaeothripine species. It has been recorded from India, Singapore, Indonesia, Thailand, Cambodia, Timor Leste ( Mound & Tree 2019) and China ( Dang et al. 2020), and newly recorded here from Vietnam and Taiwan. However, this species exhibits structural variation, such as the color of tibiae and intermediate antennal segments, the proportion of head, the width of maxillary stylets or bridge, the size of ocelli and fore tarsal apical tooth, and the length of major body setae. Moreover, it is very likely that it contains one or more different species, and will need to be re-examined. Pitkin (1976) synonymized with this species under the genus Xylaplothrips View in CoL three species described from India by Ananthakrishnan (1966) and Ananthakrishnan and Jagadish (1967), but without morphological as well as taxonomic consideration. However, this treatment is somewhat questionable. At least one synonymous species, Xylaplothrips longus Ananthakrishnan & Jagadish View in CoL , has the intermediate antennal segments entirely yellow and much slenderer than those of inquilinus View in CoL according to the original description, and we consider that there is a possibility that it is a distinct species.

Three species described in this paper, M. brevisetis sp. nov. from the Ryukyu Islands, Japan, M. eximius sp. nov. from Vietnam and M. ichikaianus sp. nov. from Honshu, Japan, may be closely related to this species. Among them, two species may be predators of other phlaeothripine species as is inquilinus : brevisetis was taken on Elaeocarpus sylvestris leaves together with Liothrips horutonoki , and eximius was taken from Quercus sp. leaves together with undetermined Liothrips species. However, ichikaianus was collected together with Xylaplothrips togashii from a common bamboo species, Phyllostachys heterocycle , and feeding habit is uncertain but may be predatory. They share some character states with inquilinus as follows: antennal segments III and IV with three (1+2) and four (2+2 +1) sense cones respectively; intermediate antennal segments largely yellowish; maxillary bridge relatively wide; fore tarsus with an apical tooth; mesopresternum reduced medially. These four species are very similar to Xylaplothrips fuliginosus , the type-species of the genus, and its relatives described from Europe in most features other than the sense cone formula.

A series of specimens listed below from Java and Bali, Indonesia, are approximately consistent with the original description in color and structure, and are identified here as this species. Most of them were collected on the leaves of Terminalia catappa ( Combretaceae ) together with Gigantothrips elegans , although it has been known as an invader of the leaf galls of other phlaeothripine species, and it seems to be a predator of G. elegans . One male from Vietnam and one female from Taiwan listed under the specimens examined may also represent this species, but have somewhat darker mid tibiae. Two females ( Figs 100 & 101 View FIGURES 94–101 ) listed below from Cameron Highland, Peninsular Malaysia, under the doubtful specimens are very similar to this species, but have several differences and likely to be a distinct species. More specimens are needed for a decision. These females have a somewhat longer head ( Fig. 100 View FIGURES 94–101 ), narrower maxillary bridge, smaller ocelli and larger fore tarsal apical tooth. In addition, their compound eyes are more or less coarsely facetted. Moreover, according to the original description ( Karny 1913) and Fig. 132 View FIGURES 130–137 in Dang et al. (2014, p. 61), these females are very similar to Glenothrips biuncinatus (Karny) , but without fore tibial inner sub-apical tooth.

Diagnosis. Distended body length: female 1.8–2.3mm, male 1.5–1.8. Body largely dark brown ( Fig. 61 View FIGURES 57–69 ); fore tibia yellowish, mid tibia shaded with brown at basal half, hind tibia largely brown, with base and apex yellowish; antennal segments I–II and VII–VIII brown, segments III–VI yellowish, shaded apically with brown, usually segment V a little paler than IV and VI. Head ( Fig. 94 View FIGURES 94–101 ) about 1.4 times as long as wide, weakly sculptured with transverse reticles or striae; postocular setae expanded. Ocelli well developed, in contact with eyes. Antennal segment VIII rather slender ( Fig. 99 View FIGURES 94–101 ), weakly constricted basally, narrowly joined to VII; segment III with three (1+2) and IV with four (2+2 +1) long and slender sense cones which are almost as long as width of these segments. Maxillary stylets scarcely reaching postocular setae, wider apart, almost V-shaped; maxillary bridge a little wider than 1/2 of head width. Four pairs of prothoracic setae well developed, expanded, but am reduced. Mesopresternum ( Fig. 96 View FIGURES 94–101 ) transverse, narrow at middle, often divided. Mesonotal lateral setae well developed, expanded. Metanotal median pair of setae rather close together and rather far from anterior margin. Fore tarsus ( Fig. 97 View FIGURES 94–101 ) with a minute apical tooth. Pelta ( Fig. 95 View FIGURES 94–101 ) trapezoid, distinctly reticulate. Tergites III–VIII S2 setae usually pointed or bluntly pointed. Tergite IX S1 and S2 setae pointed, S1 a little shorter than tube, S2 a little longer than tube; intermediate setae shorter than half of S1. Tube ( Fig. 98 View FIGURES 94–101 ) a little longer than half of head length in female; terminal setae about 1.2 times as long as tube. Males do not show extreme allometric growth.

Specimens examined. Indonesia, Java, 1 female, Yogyakarta, Campus of Gadjah Mada University , on Schefflera sp. leaves, 19.viii.2005, SO ; Indonesia, Bali, Buleleng, Pura Balatung, on Terminalia catappa leaves, 4 females and 4 males, 30.viii.2005, 12 females and 32 males, 17.viii.2006, SO . Vietnam, 1 male, Thua Thien Hue Prov. , Phu Loc District, Bach Ma National Park, ca 1150m alt., on bamboo, 14.viii.2007, SO . Taiwan, 1 female, Pintung Hsien, Kenting Nat. Park , on Ficus gall, 17.iii.1984, SO .

Doubtful specimens. Peninsular Malaysia, Cameron Highland, 1 female, foot of Gnung Brinchang, marginal leaf roll of unknown plant, 26.viii.1990, TN & SO; 1 female, nr. Brinchang, on leaves of? Sapium sebiferum ( Euphorbiaceae ), 27.viii.1990, TN & SO.