Adrothrips intermedius (Bianchi)

Mound, Laurence A., Tree, Desley J. & Wells, Alice, 2022, Convoluted maxillary stylets among Australian Thysanoptera Phlaeothripinae associated mainly with Casuarinaceae trees, Zootaxa 5190 (3), pp. 301-332 : 307-308

Adrothrips intermedius (Bianchi)

( Figs 4 , 14 , 23 , 35 )

Scopaeothrips intermedius Bianchi, 1945: 254

This species was described originally from New Caledonia, from one female and three males taken on the indigenous tree Casuarina collina . The holotype and one male were studied subsequently, and Mound (1970) recognised and illustrated the remarkable condition of the elongate and multiply coiled maxillary stylets ( Fig. 14 ). As indicated below, it is a widespread species in Australia that varies in size; specimens in the northern tropical area are distinctly paler, and specimens in the far West darker with longer antennae. However, there are no consistent structural differences among the samples listed here, and they share the following character states :

Macropterae. Body largely yellow and varying in extent of brown markings; head with light brown area posteromedially, pronotum with pair of dark areas; mesonotum dark laterally; metanotum variably brown with paler area anteromedially ( Fig. 23 ); metaepimera dark; tergites II–VII with pair of dark areas extending across anterior margin; tube varying from dark to almost yellow; legs with light brown shadings medially on femora and tibiae; antennal segments I–III paler than IV–VIII; fore wings clear, all major setae translucent. Head about as long as wide, genae convex; postocular setae acute to weakly capitate; vertex reticulate with markings internal to each reticle. Maxillary stylets retracted to posterior margin of eyes, crossing over each other medially then again posterior to occipital ridge, each in a coil posterolaterally before entering mouth cone. Both of the coils comprise several rings ( Fig. 14 ), and the number varies between localities; in most populations 4–5 but with up to 6 in Western Australia and only 2–3 in some specimens from Carnarvon Gorge, Queensland. Antennal segment III 1.4–1.8 as long as wide with no sense cone, IV with 2 sense cones, apex of V weakly asymmetric with one short stout sense cone and one small thin sense cone on inner apical margin ( Fig. 4 ). Pronotum extensively but weakly reticulate medially, reticles with inner markings, setae weakly capitate. Metanotum reticulate, reticles with internal markings, bearing 20–24 small setae ( Fig. 23 ). Fore tarsus with tooth, large males with tooth larger than small males. Prosternal ferna transverse; mesopresternum variable with pair of lateral triangles sometimes extending medially; mesoeusternum anterior margin transverse but convex medially in large male; metathoracic sternopleural sutures long and slender. Pelta broadly bell-shaped; tergites extensively reticulate, reticles with internal markings, II–VII each with two pairs of wing-retaining setae but posterior pair much stronger than anterior pair on each tergite; tergite IX setae capitate, shorter than basal width of tube; tube broader near base than in apical third ( Fig. 35 ). Sternites II–VII of larger males with transverse band of irregular specialised reticulation.

Specimens studied. Specimens identified as A. intermedius have been studied from many areas across Australia. In the Australian Capital Territory it lives on C. cunninghamiana . New South Wales in areas near the coast (Batemans Bay, Sydney, Gosford, Pottsville) it lives on C. glauca . South Australia, around Whyalla, it lives on C. glauca . Victoria, at Mildura populations have been found on C. pauper but also on Allocasuarina luehmanni . Queensland in the southeast (Dalby, Moonie) the species lives on C. cristata , but at Noosaville it has been taken from C. equisetifolia . Western Australia, at various sites near the West coast (Murchison River crossing southeast of Kalbarri; Northampton 60km east; Gingin north of Perth; East Freemantle) this species has been found on C. obesa . The specimens from these western localities have antennal segment III more elongate than any specimens from eastern localities (1.8 times as long as wide, in contrast to 1.4–1.6 times). They also usually have the metanotum more extensively brown.

Micropterae, of both sexes, have been studied. Samples from Carnarvon Station and Charters Towers (Queensland), as well as from Bourke (New South Wales), included a few micropterae of both sexes. At various sites across Australia, males have been found with the frons produced medially between the eyes into a small papilla, and this in some males is enlarged and prolonged ventrally. As with the presence of specialised reticulate areas on the sternites of males, this structure on the frons is associated with, but not closely correlated with, body size .

Figures

FIGURES 2–10. Adrothrips species antennae. (2) aureus; (3) cotteri; (4) intermedius; (5) latrarei; (6) lihongae; (7) madiae; (8) vernoni; (9) westoni; (10) mitchelli.

FIGURES 11–19. Adrothrips heads. (11) acanthus; (12) aureus; (13) cotteri; (14) intermedius; (15) lihongae; (16) latrarei; (17) madiae; (18) systenus; (19) westoni male.

FIGURES 20–27. Adrothrips heads, metanotum & pelta. (20) vernoni holotype; (21) mitchelli holotype; (22) aureus; (23) intermedius; (24) latrarei; (25) madiae; (26) vernoni; (27) systenus.

FIGURES 28–39. Adrothrips prosternites and abdomen. (28) cotteri; (29) latrarei; (30) lihongae; (31) vernoni; (32) akanthus; (33) aureus; (34) cotteri; (35) intermedius; (36) mitchelli; (37) systenus; (38) vernoni; (39) westoni.