Tryphactothripini of India (Thysanoptera, Thripidae, Panchaetothripinae), with identification keys and a new record of Opimothrips

Abstract An identification key is provided to the four genera of Panchaetothripinae from India that are members of the Tribe Tryphactothripini, together with a key to identify all the known six Indian species of Astrothrips. Furthermore, the genus Opimothrips is newly reported from India.


Introduction
The Thripidae subfamily Panchaetothripinae currently comprises approximately 145 species in 42 genera (ThripsWiki 2019). These species breed on the leaves of a wide range of plants in tropical countries, and include the widespread pest, the Greenhouse Thrips, Heliothrips haemorrhoidalis (Bouché) (Xie et al. 2019). Within this subfamily is a tribe, Tryphactothripini, that comprises species in which the second abdominal tergite is sharply constricted anteriorly and bears complex sculpture anterolaterally. This sculpture is in the form of closely spaced, small ridges that often give the optical impression of Notes. This genus was based originally on a single species that had been described from a single female collected in New Guinea, but four generic synonyms are listed in ThripsWiki (2019).
It is an Old World genus that is restricted to tropical countries, with two species from Africa and 10 distributed between Pakistan and New Guinea (ThripsWiki 2019). These are leaf-feeding thrips, with the occasional adult found in flowers, and although adults have been taken from a wide variety of plants, suggesting the possibility of polyphagy, larvae remain unknown for most of the described species. The many published host-plant associations (Table 1) involve more than 30 plant families, with little indication of any specificity. These records are based on the collection of one or more adults from any given plant, and thus may involve a flying adult simply resting on a plant surface without feeding. Possibly these records are more of a measure of the dispersive behavior of adults, rather than an indication of the plants on which they might breed. Moreover, most of the species are known from few specimens. This combination of small sample size and lack of biological information leads to a lack of confidence in the relatively trivial structural differences that have been used to distinguish some of the species. The species of Astrothrips from India were reviewed by Bhatti (1967), with many clear illustrations in the form of line drawings, and Ananthakrishnan and Sen (1980) provided a further key to the species from India but without illustrations.

Species
No. of antennal segments No metascutum with prominent triangle. Tarsi 1-segmented. Fore wing slender, both longitudinal veins with prominent setae; costal setae shorter than costal cilia; posteromarginal cilia wavy. Tergite II of abdomen with anterior margin strongly constricted, and anterolaterally with a group of prominent strongly recurved microtrichia; tergites III-VII with transverse reticulation on anterior half; VIII with no posteromarginal comb; X divided longitudinally. Male smaller, sternites with or without slender, deeply curved, pore plates. Antennal segmentation. The 8-segmented condition of antennae is considered plesiotypic for the family Thripidae ). However, among some Panchaetothripinae genera, including Astrothrips, there are species with the distal segments fused in different combinations, such as segments VI+VII or VII+VIII, or sometimes VI-VIII or even V-VIII forming a terminal group. As a result of this fusion the number of apparent segments is reduced to seven, six, or even five. It is important to recognise that reduction in the number of segments is not necessarily a shared apomorphy, because the 7-segmented condition could arise by fusion of either VII+VIII or by VI+VII ).
Species recognition. Species level taxonomy in this genus is based on some relatively trivial character states, each of which may have been observed on very few specimens. Stannard and Mitri (1962) described aureolus from only two females and distinguished this new species from globiceps and parvilimbus. The three diagnostic characters selected by the authors (shape of antennal segment III, colour of costal setae, body colour) are now considered to be variable among more recently collected specimens. Some other character states used by authors to distinguish species in this genus have been found to be more variable with the discovery of more specimens. Bhatti (1967) described stannardi as having the major sense cone on antennal segment VI surpassing the apex of the antenna, but this has been found to be untrue on various specimens of the species collected from South India and Thailand. Wilson (1975) in his key to species treated stannardi in the group with five or six antennal segments, but in the main text under that species, he states that there are seven segments; this confusion is repeated by Ananthakrishnan and Sen (1980). Subsequent identifications that are based solely on such original descriptions may not be reliable. The male of aureolus has been unknown, but a male identified as this species from Timor Leste (in ANIC) has U-shaped pore plates on sternites IV-VII as in stannardi. Similar problems are involved in host-plant associations. For example, Bhatti (1967) described lantana from two females, but Wilson (1975) mentions weekly collections from Lantana camara near the type locality without finding this thrips. In contrast, Kudô (1995) identified three females from Nepal as lantana that were taken from a species of Quercus and an unidentified tree.

Notes. The genus was erected with the type species prakashi, collected on herbage and
Lantana leaves from Jabalpur, Madhya Pradesh (Bhatti 1967). Later, this species was collected in Sri Lanka and China (Kudô 1979;Xie et al. 2019). Diagnosis. Antennae 8-segmented, III and IV with forked sense cones. Head without conspicuous raised structure, postocular seta 4 strongly developed, ocellar hump small; maxillary palps bi-segmented. Pronotum with weakly raised sculpture. Mesoscutum not notched anteriorly; metascutum with prominent reticulate triangle. Tarsi 1-segmented. Fore wing with slender pointed setae; costal setae longer than fringe cilia; posteromarginal setae wavy. Abdominal tergite I with a postmarginal flange; II anterior margin constricted, with narrow plate like cuticular processes laterally; III-VII with transverse reticulations on anterior half, posterior half smooth; X asymmetrical, divided longitudinally. Males smaller; sternites IV-VII each with transversely elongated anteriorly concave pore plates.
Notes. The reports of O. tubulatus from Thailand and China are from grass, and hence Xie et al. (2019) reported the species as being associated with grasses. However, the present specimens have been collected from an unidentified weed.

Opimothrips tubulatus Nonaka & Okajima, 1992
Female macroptera. Body yellowish brown (Fig. 1), fore legs yellow, tarsi yellow, tibiae brown, yellow in apical half and basally, femora brown in basal half, rest yellow; antennal segments I-III golden yellow, IV-V yellow with shaded brown distally, VI-VIII dark brown; fore wing uniformly shaded with apex pale, clavus brown; first vein with 11 setae, not uniformly arranged; second vein with 6 setae. Antennae 8-segmented; sutures complete and distinct between all segments; III-IV with thin, Yshaped sense cones, the arms unusually thin and curving around the segment, narrow apex on IV shorter, wider, more abruptly constricted than III; outer sense cone on VI extending to midpoint of VIII (Fig. 3). Head wider than long; ocellar hump weakly developed, ocelli visible; major setae rudimentary; eyes not bulged, covering lateral side almost completely; genae much reduced, without protruding transparent fringe (Fig. 2). Pronotum reticulate, raised sculpture on lateral margins; median area with transverse reticulations (Fig. 2). Mesonotum anterior margin shallowly notched, not reaching beyond anterior one third; 2 pairs of small setae, the inner pair anterior to the outer pair (Fig. 4). Metanotal median triangle weakly indicated; polygonally reticulate, extending beyond posterior margin, median setae anterior to campaniform sensilla (Fig. 4). Fore wing base humped, costal setae shorter than fringe; first vein with 7 basal setae, 2 at middle and 2 distally, thin and pointed; second vein with 6 setae, curved except last three; clavus with 4 veinal setae but no discal seta; posteromarginal cilia wavy (Fig. 6). Fore tibia with a spine at apex; hind tibia with a row of 11 conspicuous spines on inner side and two stout ones at apex; hind tarsi with a spine at median on inner side and two short, stout ones at apex. Abdominal tergite I reticulations extending beyond margin; median area of II with weak reticulations, laterally with wartlike tubercles; thick sublateral antecostal line on III-VII, laterally forming a posterior directed notch; VIII with complete posteromarginal comb of minute teeth; IX with campaniform sensilla; X asymmetric, median split complete, terminal setae almost half as long as the segment (Fig. 5). Sternites II-VII with 2 pairs of marginal setae on broad craspedum; antecostal lines on III-VII with median concave invagination. Ovipositor long, well developed, exceeding abdominal apex.

Notes.
Various workers on Thysanoptera [Bagnall (1919); Margabandhu (1931, 1940); Shumsher (1947); Patel and Patel (1953); Ananthakrishnan (1954); Wilson (1975)] reported T. rutherfordi from India. However, Bhatti (1967 and1990) clarified the report of Ramakrishna and Margabandhu (1931) as Astrothrips tumiceps and of Patel and Patel (1953) from Pune as a species of Astrothrips. The records by Shumsher (1947) and Ananthakrishnan (1954) have never been validated, but Wilson (1975) collected three females from a forest tree in Tamil Nadu and compared these with the female holotype of T. rutherfordi in London. This is the only authenticated report of rutherfordi from India, and is only the second reliable report since the original description of the species from Ceylon. Diagnosis. Antennae with six segments, terminal segments fused into an elongate unit. Head with raised sculpture covering cheeks and vertex; maxillary palps bi-segmented. Pronotum with raised sculpture anteriorly and on anterolateral angles. Mesoscutum slightly notched. Tarsi 1-segmented. Fore wing with anterior vein fused to costa at fork of veins; costal setae shorter than costal cilia; posteromarginal cilia wavy. Abdominal tergite II sharply constricted, laterally with double based rod like processes; III-VII with paired clusters of round sculptured areolae, striated across anterior third, bearing pair of sigmoidal setae laterally; VIII with no posteromarginal comb; X asymmetric, divided longitudinally.