Heligmothrips brevidens (Hood)

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 : 318-319

Heligmothrips brevidens (Hood)

( Fig. 51 )

Liothrips brevidens Hood, 1918: 137

Teuchothrips spinosus Moulton, 1968: 102 .

Cryptothrips reticulaticeps Girault, 1927b: 1 syn.n.

Described from three females and four males taken by sweeping vegetation near Charters Towers in northern Queensland in 1912/13. The synonym, spinosus was described from one female taken near Newcastle in New South Wales and one male from Bribie Island, in southeastern Queensland. The single female from which Girault described reticulaticeps was collected in southeastern Queensland from mangrove at Banyo, Brisbane. This species was transferred to the genus Heligmothrips by Mound (1974: 40), but with no comment or details other than that the species was a member of the Phlaeothripinae not Idolothripinae. The maxillary stylets of the specimen do not cross over each other but are close together medially. However, a similar arrangement of the stylets has been seen in a few specimens of brevidens from Allocasuarina muelleriana on Kangaroo Island. The fore wing of the reticulaticeps holotype bears only three duplicated cilia, whereas in most specimens identified as brevidens there are between 9 and 15 duplicated cilia. Unfortunately, the reticulaticeps specimen is too contracted to observe the mesopresternum.

The maxillary stylets of H. brevidens cross over each other at the level of the postocular setae. They then recross at the posterior margin of the head, with the single posterolateral flexure usually involving no more than a single sharp turn close to the lateral margins of the mouth cone ( Fig. 51 ). There is considerable variation in body size among individuals, with females varying in body length within any single population from less than 2mm to more than 3mm. Males are equally variable in body length but are generally smaller. However, large males commonly have the pronotal anteroangular setae twice as long as the anteromarginals (much longer than in females), and the largest male studied has the anteromarginal setae scarcely larger than the pronotal discal setae. In females the pronotal setal pairs are smaller and remain almost co-equal in length regardless of body size.

The colour of the pronotal setae is usually light brown, but these setae are pale in a few specimens, and dark brown in a few others. The common form around Canberra is similar to the brevidens holotype, with the basal half of antennal segments IV–V largely yellow and the pronotal setae shaded. But in the series from Kangaroo Island the antennae are largely brown and the pronotal setae varying from weakly shaded to pale. The fore wing also varies among populations in the extent of brown shading, despite having been considered “pale” by Hood. Despite these variations, the specimens listed below are all considered likely to represent the same species, although the three specimens from Timor Leste are particularly unusual with slender, dark pronotal setae.

Specimens studied. Australian Capital Territory: Casuarina Sands , from C. cunninghamiana , 2 females, 1 male, 6.iv.1968 ; 3 females, 2 males, 23.x.1994 ; 4 females, 4 males, 10.xi.2002. New South Wales: near Taralga , 1 female, 1 male from C. cunninghamiana , 2.iv.1968 ; Warrumbungle N.P., 3 females from Casuarina , 13.iii.2008 . Victoria: near Mallacoota , 3 females 3 males from Allocasuarina paludosa , 29.xii.2004 . Tasmania: Lake Pedder , 1 male, 24.ii.2004 . South Australia: Kangaroo Island , 6 females 5 males from A. muelleriana , 1.xii.2021 ; Ngarkat Park , 1 female from dead wood, 4.x.2013 . Queensland: near Charters Towers , 3 males from Casuarina , 3.vii.1995 ; Hughenden , 66km north, 2 females, 1 male from Casuarina , 14.x.2015 ; Carnarvon Station , 1 female from Casuarina , 14.x.2014 , 1 female from Casuarina cunninghamiana , 11.x.2014; Brisbane, The Gap , 2 females from Casuarina , 30.xii.2006 ; Brisbane, Banyo , holotype female of reticulaticeps . Western Australia: Barrow Island , 3 females, 1 male, iv/ v.2005 . Timor Leste: Aileu , 2 females, 1 male from Casuarina , 22.viii.2018 .

Figures

FIGURES 51–59. Heligmothrips species heads and stylets. (51) brevidens; (52) erinaceus; (53) gracilior; (54) eiletus; (55) eiletus larva; (56) exallus; (57) macropus; (58) narrabri; (59) xantoskelus.