Hoplothrips Amyot & Serville, 1843

Mound, Laurence A., Wang, Jun & Tree, Desley J., 2020, The genus Hoplothrips in Australia (Thysanoptera, Phlaeothripinae), with eleven new species, Zootaxa 4718 (3), pp. 301-323 : 302-303

Hoplothrips Amyot & Serville

Hoplothrips Amyot & Serville, 1843: 640 . Type species Thrips corticis De Geer 1773 .

Most species of Hoplothrips collected in Australia have been taken from dead branches, although oudeus , woodsi sp. n. and wrightae sp. n. are known only from leaf litter samples. The species from Australia discussed here exhibit a number of unusual structural features.

Antennae: all species have eight antennal segments, but one species has unusually prominent ring-like ridges near the base segment III ( Fig. 45 ). However, this condition is found amongst several distantly related Phlaeothripidae ( Mound & Tree 2013, 2014; Eow et al. 2014). Segment IV of macropterae of semicaecus , and of both macropterae and micropterae in bellingeni sp. n., bears ventrally many small sense cones (sensilla basiconica), although micropterae of semicaecus have segment IV with a reduced number of these structures ( Figs 42–44 ).

Prosternal basantra: this pair of sclerites is absent in most species of Hoplothrips ( Figs 23, 25 ) and related genera, but they are present in three species considered here ( Figs 24, 30 ).

Fore tarsal tooth: this is present in males of all species considered here, but is absent in females of bellingeni sp. n., tarsus sp. n. and fungosus .

Metanotal setae: the median pair of setae is usually small and acute, but in one species these setae are capitate ( Fig. 53 ), and in another species the metanotum bears several pairs of minor setae ( Fig. 50 ).

Fore wing duplicated cilia: macropterae of most species in this genus have these cilia, but they are absent in four species considered here ( fungosus , connexus , reedi sp. n. and tarsus sp. n.).

Tergites II–VII sigmoid wing-retaining setae: macropterae usually have two pairs of such setae on tergites II–VII, but these setae are absent on all tergites in reedi sp. n.; they are absent on tergite VII in giganteus sp. n.; and only one pair is sigmoid on each tergite in oakeyi sp. n., lihongae sp. n., fungosus and connexus .

Male sternite VIII pore plate: although present in most species ( Figs 57–64 ), this is absent in bellingeni sp. n., lowdeni sp. n., giganteus sp. n. and fungosus .

As a result of the extensive structural diversity, the generic diagnosis given below involves many exceptions. Considered worldwide, one series of species in the genus has been referred to as the H. fungi complex ( Mound 2017), and this comprises at least seven species ( corticis , dubius, fungi , japonicus , karnyi , orientalis and ulmi). This is essentially an Holarctic group, but at least four species from Australia share many character states with the members of the H. fungi complex ( lihongae , oakeyi , poultoni , wrightae ) and two others are also rather similar ( giganteus , lamingtoni ). In three species discussed below the head is similar to that of members of the fungi -complex, with elongate maxillary stylets that are close together medially ( melanurus , oudeus , semicaecus ), but each of these is distinguished by a singular autapomorphy. Similarly, despite being generally similar to H. fungi , two species ( reedi , tarsus) have the remarkable condition of the notopleural sutures being incomplete anteriorly ( Fig. 17 ). Finally, three species ( bellingeni , convexus, nelsoni ) have the maxillary stylets wider apart than is typical of Hoplothrips ( Figs 1–8 ). Two of these are thus similar to some members of Psalidothrips , although bellingeni has antennae very similar in structure to semicaecus , a species with a typical Hoplothrips -like head. It thus seems likely that there has been considerable structural homoplasy in the evolutionary radiation of these fungus-feeding thrips.

In addition to the many specimens listed as having been studied for this account, a further 25 Australian specimens have been examined but not identified. Each of these specimens could easily be assessed as representing a further undescribed species. The structural diversity within this genus is thus even greater and more complex than reported here, but will require far more extensive field work for a satisfactory analysis.

Diagnosis: Large to medium sized thrips, macropterous, micropterous or apterous. Body surface usually with linear or weakly polygonal sculpture. Head variable, longer or shorter than wide, with reticulate sculpture basally; postocular setae well developed, pointed or capitate, varying between species from much longer to shorter than eye length; maxillary stylets long, at least retracted to postocular setae, usually close together medially but sometimes sub-parallel medially. Antennae 8-segmented, III with 3 or 2 sense cones, IV with 2–4 (usually 4). Pronotum usually with 5 pairs of major setae, pointed or capitate, but am and ml sometimes not developed; notopleural sutures complete, or rarely incomplete anterolaterally. Prosternal basantra usually absent, rarely present; mesopresternum variable, from boat-shaped to three or two plates, or even absent; mesoeusternal anterior margin usually entire but sometimes strongly eroded; metathoracic sternopleural sutures present. Mesonotum usually weakly reticulate, metanotum sometimes reticulate medially; fore tarsal tooth usually present in both sexes, but often absent in female; fore wings usually not constricted medially, duplicated cilia usually present. Pelta usually reticulate, shape variable, campaniform sensilla present; tergites II–VII each with two pairs (rarely one pair) of wing-retaining setae, but these are short and straight in wingless individuals; tube shorter than head, anal setae length variable; male sternite VIII usually with pore plate; males often with areas of specialized reticulation anterolaterally on several sternites.

Figures

FIGURES 31–45. Hoplothrips species antennae. (31) bellingeni; (32) corticis (III–V); (33) giganteus; (34) lihongae; (35) lowdeni; (36) nelsoni; (37) oakeyi; (38) wrightae; (39) orientalis (III–V); (40) poultoni; (41) reedi; (42) semicaecus female macroptera; (43) semicaecus female microptera; (44) semicaecus male microptera; (45) woodsi.

FIGURES 21–30. Hoplothrips species. Head 21–22 (21) wrightae female; (22) wrightae male. Prosternum 23–30 (23) bellingeni; (24) fungosus; (25) lihongae; (26) lowdeni male; (27) tarsus; (28) wrightae; (29) reedi; (30) woodsi (B–basantra; F–ferna; M–mesoeusternum anterior margin).

FIGURES 53–66. Hoplothrips species. Metanotum & pelta 53–54 (53) oudeus; (54) woodsi. (55) tarsus pelta. (56) lamingtoni tergite II. Male sternite VIII pore plate 57–64 (57) corticis; (58) lihongae; (59) wrightae; (60) oakeyi; (61) reedi; (62) melanurus (VII–VIII); (63) poultoni; (64) woodsi. Male sternites 65–66 (65) giganteus (VII); (66) melanurus (V–VI).

FIGURES 46–52. Hoplothrips species—metanotum & pelta. (46) bellingeni; (47) corticis; (48) giganteus; (49) lamingtoni; (50) melanurus; (51) oakeyi; (52) orientalis.

FIGURES 10–20. Hoplothrips species—head and pronotum. (10) lowdeni male; (11) lowdeni female; (12) nelsoni male; (13) nelsoni female; (14) oakeyi female; (15) oakeyi male; (16) reedi male; (17) reedi pronotum; (18) melanurus pronotum; (19) tarsus; (20) semicaecus female macroptera.

FIGURES 1–9. Hoplothrips species—head and pronotum. (1) bellingeni female; (2) bellingeni male; (3) corticis; (4) fungosus female aptera; (5) fungosus female macroptera; (6) fungosus male aptera; (7) giganteus; (8) lamingtoni; (9) lihongae.