Tenothrips merae, 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 : 207-209

Thrips merae sp. n.

This species ( Figs 49 – 55 ) is a member of a species-group within Thrips genus that is otherwise known only from New Zealand ( Mound & Masumoto 2005). Members of this species-group have three pairs of posteromarginal setae on the second abdominal sternite, whereas species of this genus from the rest of the world have only two pairs. This new species is closely similar to Thrips obscuratus , the New Zealand flower thrips that is abundant throughout that country, and is similarly variable in size and colour. However, T. merae differs particularly in having the metanotum much less closely striate. Moreover, even when compared with specimens of obscuratus of equal wing length, merae females have a shorter third antennal segment, fewer pronotal discal setae, and shorter microtrichia medially to the comb on tergite VIII. The males have sternal pore plates that are never more than four times as wide as long, and all available specimens have only seven antennal segments. In contrast, males of obscuratus have pore plates that are six or more times as wide as long, and both sexes commonly have eight antennal segments. Populations of this new species have been found only in association with the Norfolk Island critically endangered endemic plant, Myoporum obscurum , of which there are small numbers growing in the National Park as well as a few cultivated specimens in other parts of the island. In New Zealand, T. obscuratus is highly polyphagous, and breeds in the flowers of a very wide range of native and introduced plants.

Female macroptera: Body, legs and antennae brown, tarsi paler (teneral individuals light brown), fore wings brown but slightly paler at base. Head transversely striate, ocellar triangle almost without sculpture; ocellar setae pair III as long as an ocellus, arising just outside the triangle; postocular setae pairs I, III and V as long as ocellar setae ( Fig. 49 ). Antennae 7-segmented. Pronotum ( Fig. 49 ) usually transversely striate/reticulate, with less than 10 discal setae; posterior margin with 3 (or 4) pairs of marginal setae. Fore tarsus simple, without a terminal claw. Fore wing ( Fig. 55 ) with two complete rows of setae; clavus with 5 marginal and one long discal setae, terminal and subterminal marginal setae subequal. Mesonotum transversely reticulate, anterior campaniform sensilla present. Metanotum ( Fig. 51 ) transversely striate at anterior, with irregular striations on posterior half, median setae long and arising behind anterior margin; campaniform sensilla present. Tergite II with 3 lateral marginal setae; II– IV with lines of sculpture extending just mesad of median setae and campaniform sensilla; V–VIII with paired ctenidia laterally; VIII with posteromarginal comb of small, irregular microtrichia ( Fig. 52 ); X with short median split. Sternites II–VII each with 3 pairs of marginal setae, II with no discal setae, III–VI with about 10, VII with about 7 discal setae ( Fig. 54 ).

Measurements (holotype female in microns). Distended body length 1500. Head, length 85; width across eyes 155; ocellar setae III 25. Pronotum, length 130, width 200; posteroangular setae 65. Metanotum median setae 45. Fore wing, length 800. Antennal segments III–VII length 45, 43, 35, 55, 20.

Male macroptera: Similar to female in colour and structure, but smaller with abdomen more slender; tergite VIII without posteromarginal comb, IX with four setae arising in transverse row with median pair longer than lateral pair; sternites III–VII each with transversely oval pore plate, larger on anterior than on posterior segments, maximum width varying but less than four times as wide as median length ( Fig. 53 ).

Specimens studied: Holotype female, Norfolk Island, Mt Bates, from flowers of Myoporum obscurum , 22.iii.2014 (LAM5917).

Paratypes: 10 females, 16 males taken with holotype; same site, 1 female, 1 male from dead Rhopalostylis frond, 24.x.2013, 1 male, beaten from foliage, 24.xii.2013; Palm Glen Track, from M. obscurum , 1 female 24.iii.2014, 2 females 24.xi.2014; Mt Pitt, 1 male from Dodonaea leaves, 26.iii.2014; Burnt Pine, Hillies Restaurant, 3 males from M. obscurum , 24.xi.2014.

Thrips nigropilosus Uzel: This species is found worldwide in temperate areas, breeding on many different plant species, particularly lettuce and pyrethrum. In December 2012, the lower leaves of a crop of young Cos lettuce plants on Bullocks Hut Road were found to have considerable damage in association with large numbers of this thrips. The only other specimens of nigropilosus found were also on a lettuce crop, in February 2014.

Thrips novocaledonensis Bianchi ( Fig. 39 ): This species occurs in abundance everywhere on Norfolk Island. It appears to breed only in flowers, and was found in virtually every type of flower on the island that was examinedin gardens, vegetable areas, and forests. The original specimens studied by Palmer (1992) that provided the basis for the record of Thrips hawaiiensis from Norfolk Island ( Smithers 1998) have been re-examined and correctly identified as T. novocaledonensis . This species is not known from the Australian mainland, but was described from New Caledonia and is recorded from Vanuatu. Frequently males were observed on Norfolk Island forming aggregations, sometimes on individual flowers, but sometimes on the leaves of plants that did not bear any flowers. The significance of these aggregations to breeding behaviour remains unknown.

Thrips simplex (Morison): The gladiolus thrips is found worldwide, wherever Gladiolus is cultivated, although it presumably originated in South Africa. Feeding damage usually takes the form of streaking on the flowers. One population was found on Norfolk Island, on some flowering Gladiolus plants growing as weeds on open land near the start of Palm Grove Track.

Thrips tabaci Lindemann: The onion thrips is found throughout the world, except in the wet tropics. It is highly polyphagous, and large numbers of females were found on Norfolk Island on leeks and shallots, as well as carrots, young cabbages, and young bean plants, often in association with considerable leaf damage. It was particularly abundant in November 2014 after several months during which little rain had fallen.

Figures

FIGURES 49 – 55. Thrips merae sp. n. (49) Head and pronotum; (50) Antennal segments II – VIII; (51) Mesonotum and metanotum; (52) Tergites VII – IX; (53) Male sternites IV – VII; (54) Female sternites VI – VII; (55) Fore wing.

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.