Scirtothrips araucariae, Mound, Laurence A. & Wells, Alice, 2015

Mound, Laurence A. & Wells, Alice, 2015, Endemics and adventives: Thysanoptera (Insecta) biodiversity of Norfolk, a tiny Pacific Island, Zootaxa 3964 (2), pp. 183-210 : 205-207

Scirtothrips araucariae sp. n.

This species ( Figs 43 – 48 ) is widespread across the island, but breeds only on the young terminal leaf tissues of Araucaria heterophylla . It is either endemic to the island or, like Neophyllaphis araucariae that occurs in low numbers on the same trees, possibly a natural immigrant from an Araucaria species on New Caledonia or eastern Australia. According to the key to Australian species of Scirtothrips ( Hoddle & Mound 2003) it is similar in many character states to S. australis , including the absence of microtrichia on abdominal tergites IX and X. However, in contrast to this new species, australis has one pair of pronotal posteromarginal setae about 50 microns long, and the postocular setal row lacks a minute seta between the two major setae.

Female macroptera: Body and legs pale brownish-yellow with no dark markings except antecostal ridge shaded on sternites IV–VII ( Fig. 46 ); antennal segment I as pale as head, II usually slightly darker, III–VIII light brown; fore wing and clavus weakly shaded, setae brown.

Antennae 8-segmented ( Fig. 44 ), forked sense cone on III–IV short, not reaching more than one-third the length of succeeding segment; external sense cone on VI stout. Ocellar triangle on head with transverse reticulate striae; ocellar setae III not longer than length of one posterior ocellus, arising between hind ocelli; postocular setae I and III slightly shorter than ocellae setae III, postocular setae II and IV minute, usually shorter than diameter of basal pore ( Fig. 43 ) [postocular seta I sometimes absent on one or both sides]. Pronotum closely striate, with irregular median transverse row of 6 discal setae; 4 pairs of posteromarginal setae, pair S2 less than twice as long as S1. Metanotum reticulate, median setae short and arising just posterior to anterior margin ( Fig. 47 ). Fore wing second vein with 3 setae; first vein with group of 3 setae sub-basally, then about 4 setae, and 3 (or 4) setae on distal half; clavus with 4 veinal and one discal setae; distal posteromarginal cilia straight, but some cilia wavy nearer middle of wing. Abdominal tergites II–III with median setae (S1) small and closer together than their length, but on IV–VII S1 setae increasingly long and further apart; lateral microtrichial fields with only 2 discal setae; VIII with marginal comb of microtrichia, but no discal microtrichia medially ( Fig. 48 ); IX–X with no discal microtrichia. Sternites with lateral microtrichial fields scarcely extending mesad of marginal setal pair S2 ( Fig. 46 ).

Measurements (holotype female in microns). Distended body length 900. Head, length 85; width across eyes 150; ocellar setae III 12. Pronotum, length 90, width 160; posteromarginal setae S1 10, S2 15. Metanotum median setae 15, submedian setae 25. Fore wing, length 600; veinal setae 10–20. Tergite median setal length, on III 10, distance between their bases 15; on VII 15, distance between their bases 25. Antennal segments III–VIII length 40, 30, 35, 40, 6, 12.

Male: Not known.

Larvae: Yellow, weakly shaded anterolaterally on head, also antennal segment II and apex of abdominal segment X. Body surface very finely granulate with no reticulate sculpture; major setae finely pointed, scarcely 10 microns long except 25 microns on tergite IX; mesothoracic spiracles well developed, remaining spiracles very small.

Specimens studied: Holotype female, Norfolk Island, Highland Lodge, from young terminal leaves of Araucaria heterophylla , 21.iii.2014 (LAM 5908).

Paratypes, all from Norfolk Island and same host plant: 6 females taken with holotype and larvae; Palm Glen Track, 7 females, 21.iii.2014; Ball Bay Reserve, 4 females, 24.iii.2014; Capt. Cook Reserve, 3 females, 24.iii.2014; Burnt Pine, 2 females, 26.ii.2014; Red Road, 1 female from shrubs growing beneath Araucaria , 27.xii.2012; Mt Bates, 5 females with larvae, 25.xi.2014.

Scirtothrips inermis Priesner : During December 2013 and May 2014 females were found in good numbers on the young leaves of peach and citrus trees at several localities across the island, including Two Chimneys Road and Highland Lodge. This thrips has been taken in low numbers on Lord Howe Island and also mainland Australia, and has been reported as possibly native to the Canary Islands. Although common and widespread, inermis does not seem to be considered a serious crop pest, in contrast to some members of this genus. Particularly curious is the apparent absence of any species of Scirtothrips on tree ferns on Norfolk Island, in contrast to the situation in eastern Australia and Lord Howe Island ( Mound & Hoddle 2003).

Tenothrips frici (Uzel) ( Fig. 36 ): This southern European species is widespread around the world. In south-eastern Australia it breeds in the yellow flowers of weedy Asteraceae that are often called “dandelions”. The species was not common on Norfolk Island, but a small population was found in Hieraceum flowers in December 2013 at Bullocks Hut Road, and in the same week two females were taken in a yellow pan-trap near the start of Palm Grove Track. However, in November 2014 adults were found on Hieraceum flowers at several sites across the island, including Anson Bay, Mission Road, and Prince Philip Drive.

Thrips australis (Bagnall) ( Fig. 40 ): The gum-tree flower thrips is abundant across most of Australia, breeding in the flowers of many species of Eucalyptus , and commonly existing as vast populations ( Mound & Masumoto 2005). On Norfolk Island it was found in large numbers in the flowers of trees in the National Park Eucalyptus plantation . One large sample was beaten from the leaves of Dodonaea at the top of Mt Pitt in March 2014. This sample comprised newly emerged adults of both sexes that presumably had come from trees flowering in the Eucalyptus plantation at the foot of Mt Pitt.

Thrips imaginis Bagnall: At the time of the surveys reported here this species had NOT been found on Norfolk Island, although as indicated above, adults were taken on Phillip Island in October 2014. This island is approximately 2km square and lies 6km south of Kingston Jetty on Norfolk Island. It was heavily denuded by rabbits and goats for at least 100 years, but the National Park authorities have an active programme of revegetation. Currently there is no explanation concerning how this abundant Australian thrips species has become established on Phillip Island but not on Norfolk Island itself.

Figures

FIGURES 43 – 48. Scirtothrips araucariae sp. n. (43) Head and pronotum; (44) Antennal segments II – VIII; (45) Tergites IV – VI; (46) Sternites V – VII; (47) Mesonotum and metanotum; (48) Tergites VII – IX.

FIGURES 33 – 42. Thripidae species. (33) Anaphothrips dubius; (34) Anaphothrips sudanensis; (35) Apterothrips apteris; (36) Tenothrips frici; (37) Chaetanaphothrips orchidii; (38) Aptinothrips rufus; (39) Thrips novocaledonensis; (40) Thrips australis; (41) Hercinothrips bicinctus; (42) Plesiothrips perplexus.