Scirtothrips cyatheae, Mound & Wells, 2023

Mound, Laurence A. & Wells, Alice, 2023, Endemism among Lord Howe IslandThysanoptera, with new species of Baenothrips (Phlaeothripidae) and Scirtothrips (Thripidae), Zootaxa 5228 (1), pp. 81-91 : 86-87

Scirtothrips cyatheae sp.n.

( Figs 15, 17–20 , 23, 24 )

Female macroptera. Body colour (in life) medium brown, paler on tarsi, base of antennal segment III and apex of segment II; fore wings brown with major setae dark. Antennae 8-segmented ( Fig. 24 ), forked sense cone on III and IV not reaching more than one-third the length of succeeding segment; inner sense cone on VI extends almost to apex of VIII. Head with ocellar triangle lacking sculpture lines ( Fig. 15 ); ocellar setae pair III no longer than a posterior ocellus, varying in position from just in front of, to clearly posterior to, the tangent between hind margins of the hind ocelli; postocular setae I–III shorter than ocellar setae pair III. Pronotum transversely reticulate, distance between transverse striae commonly more than twice the diameter of a discal seta base ( Fig. 15 ); 4 pairs of posteromarginal setae, S2 shorter than diameter of antennal segment II, S4 minute. Metanotum reticulate, median setae short and arising posterior to anterior margin ( Fig. 17 ). Fore wing second vein with 4 (rarely 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 almost straight but with apical thirds weakly wavy. Abdominal tergites II–VIII with setae S1 arising closer together than their length ( Fig. 18 ); lateral microtrichial fields with 3 discal setae; VIII with long marginal comb but no discal microtrichia medially ( Fig. 19 ); IX–X with no discal microtrichia. Sternites with lateral microtrichial fields usually not extending mesad of marginal setal pair S2.

Measurements (holotype female in microns). Distended body length 870. Head, length 65; width across eyes 115; ocellar setae III 10. Pronotum, length 90, width 140; posteromarginal setae S1 10, S2 20, S3 20, S4 10. Metanotum median setae 12, submedian setae 25. Fore wing, length 530. Tergite median setae length, on III 10, on VII 15, on VIII 40. Antennal segments III–VIII length 30, 25, 30, 40, 8, 10.

Male: Colour and sculpture similar to female; tergite IX with pair of drepanae extending to midpoint of segment X.

Larva II: Abdomen and pterothorax densely covered with minute tubercles ( Fig. 23 ), head and pronotum with fewer of these tubercles but lacking sclerotised plates.

Specimens studied. Holotype female, Australia, Lord Howe Island , Mt Gower, Erskine Valley, from Cyathea young frond, 21.xii.2007 (LAM 5130), in ANIC.

Paratypes, all Lord Howe Island : 1 male, 7 females (also larvae) taken with holotype; same locality and host plant, 11 females, 27.xii.2001 . Rocky Run , 3 males, 5 females (also larvae), from Cyathea young fronds, 22.xii.2001 ; same locality and host plant, 6 males, 5 females (also larvae), 24.xii.2007 . Soldiers Creek , 1 male, 3 females, from ferns, 25.xii.2001 .

Comments. This species is unusual among member of the genus Scirtothrips in having the pronotal sculpture lines widely spaced ( Fig. 15 ). It shares this condition not only with the new species described below, but also with S. frondis , a species that lives on the young fronds of tree ferns in eastern Australia ( Mound & Tree 2020), as well as S. pan that has a similar host association in New Zealand ( Mound et al. 2017). From these it differs in being brown rather than mainly yellow in colour, and in having no sculpture lines within the ocellar triangle. From frondis it further differs in having ocellar setae pair III slightly more posterior in relation to the hind ocelli, and from pan it differs in having much shorter setae on the head and first abdominal tergite. The second instar of frondis also lacks the sclerotised plates with reticulate sculpture that occur in many species of Scirtothrips .

Figures

FIGURES 14–22. Scirtothrips species. Head & pronotum 14–16: (14) albomaculatus; (15) cyatheae; (16) gymnos. Female cyatheae 17–20: (17) Metanotum; (18) Tergites I–III; (19) Tergites VI–X; (20) Sternites VI–VIII. Female gymnos 21–22: (21) Tergites IV–VIII; (22) Tergites V–VI.

FIGURES 23–24. Scirtothrips cyatheae. (23) Larva II abdomen. (24) Female antenna.