Terthrothrips trigonius, Tong, 2017

Tong, Xiaoli, 2017, Two new species and a new record of the fungivorous genus Terthrothrips from China (Thysanoptera: Phlaeothripidae), Zootaxa 4323 (4), pp. 561-571 : 566-570

Terthrothrips trigonius sp. n.

( Figs. 10–20 , 23, 24 )

Female. Aptera ( Fig. 23 ). Body, legs and antennae mainly brown except for all tarsi, abdominal tergite IX and apex of tube light brown; major setae colourless to weakly shaded.

Head ( Fig. 10 ) approximately 1.3 times as long as wide, broadest across cheeks near base, slightly projecting in front of eyes; dorsal surface with striate sculpture but weak medially; cheeks slightly rounded and incut behind eyes. Eyes slightly shorter than 1/4 of head length, smaller ventrally than dorsally ( Fig. 11 ); postocular setae capitate and approximately 1.5 times as long as eye length; ocelli present; postocellar setae pointed and as long as diameter of posterior ocelli. Antennae ( Fig.20 ) approximately 2.1 times as long as head length; segments III and IV each with 3 sense cones; segment VI longer than VIII; terminal setae much longer than the combined length of segments VII and VIII. Maxillary stylets retracted slightly into head capsule, approximately half of head width apart. Mouth-cone short and rounded.

Pronotum ( Fig. 13 ) smooth, with a reduced median longitudinal line; notopleural sutures almost complete; pronotal aa and am reduced, almost invisible, pronotum with only 3 pairs of well developed capitate setae (ml, epim and pa); basantra present, but membranous, paired ferna well-developed with two pairs of setae situated at anterior margin. Mesonotum with pair of short and fine lateral setae; mesopresternum boat-shaped with a projection medially ( Fig. 14 ), with prospinasternum developed. Metanotum entirely smooth, median setae small and acute ( Fig. 15 ); metathoracic sternopleural sutures absent. Fore tibiae without tubercles on inner margin; fore tarsal tooth distinct ( Fig. 12 ).

Pelta ( Fig. 19 ) almost triangular, dorsal surface smooth, a pair of campaniform sensilla present; abdominal tergites without wing retaining setae; sternites II–VIII with transverse row of 6–18 discal setae medially, each with 2 pairs of long and stout setae arising in front of posterior margin, but VIII with an additional pair of short and fine setae situated at posterior margin ( Fig. 17 ); tergite IX setae S1 and S2 subequal in length but distinctly shorter than tube, both expanded at apex; intermediate setae (iS) pointed, approximately 0.6 times as long as S1 setae ( Fig. 16 ); tube length approximately 2 times basal width, 0.6 times as long as head; anal setae half the length of tube.

Measurements (holotype female in microns). Distended body length 1720. Head length 250, width 175; eyes length 50; postocular setae length 75; diameter of anterior (posterior) ocelli 18; postocellar setae length 16. Antennae length 530, segments I–VIII length (width) as follows: 52(45); 51(34); 89(30); 90(33); 86(26); 66(18); 47(18); 47(15); terminal setae length 140. Pronotum median length 125, width across median part 280; length of major setae: midlateral setae 65, posteroangular setae 75, epimeral setae 65. Metanotum median setae 30. Pelta length 70, width at base 140; abdominal tergite IX setae S1 length 108, intermediate setae length 67, S2 length 108. Tube length 140, width at base 65, at apex 35; anal setae length 70.

Male. Aptera ( Fig. 24 ). Color and structure similar to apterous female except for fore femora somewhat enlarged; abdominal sternite VIII without pair of setae situated at posterior margin ( Fig. 18 ); sternite IX with a pair of prominent setae medially; tergite IX setae S2 acute and much short than S1.

Measurements (paratype male in microns). Distended body length 1470. Head length 240, width 160; eyes length 55; postocular setae length 72; diameter of anterior (posterior) ocelli 17; postocellar setae length 15. Antennae length 490, segments I–VIII length (width) as follows: 44(31); 44(26); 84(25); 85(25); 83(23); 63(18); 40(18); 46(11); terminal setae length 125. Pronotum median length 135, width across median part 255; length of major setae: midlateral setae 82, posteroangular setae 70, epimeral setae 70. Metanotum median setae 25. Pelta length 65, width at base 120; abdominal tergite IX S1 setae length 103, intermediate setae length 65, S2 setae length 17. Tube length 120, width at base 70, at apex 35; anal setae length 65.

Material examined. Holotype. Female aptera, CHINA, Guangdong, Lianxian County, Mt. Dadongshan (24°55'N, 112°42'E), 28.ix.2010, Tao Song.

Paratypes. CHINA, Guizhou: 2 males, Jiangkou County, Fanjingshan National Nature Reserve (27°53'27"N, 108°46'45"E), 10.viii.1987, Xiaoli Tong . Hunan: 1 male, Zhangjiajie National Forest Park (29°22'26"N, 110°28'16"E), 11.viii.1987, Xiaoli Tong ; 1 female, Yanling County, Shennong Valley (26°29′N, 114°01′E), 24. viii. 2015, Chao Zhao. Guangdong: 1 male, Meizhou City, Mt. Yinnashan (24°26'N, 116°09'E), 15.xi.2014, Chao Zhao.

Etymology. Specific epithet from Latin “ trigonius ” which means triangular, and refers to the almost triangular pelta of this new species.

Distribution. China (Guizhou, Hunan, Guangdong).

Remarks. The new species appears to be most similar in appearance to T. strasseni by sharing with dorsal surface almost smooth and fore tibiae without tubercles on inner margin, but it can be readily distinguished by the smaller eyes, approximately one-fifth of head length, which are smaller ventrally than dorsally; antennae uniformly brown; postocular setae distinctly longer than eye length; metanotum entirely smooth; pelta almost triangular and surface smooth.

Figures

FIGURES 10 – 16. Terthrothrips trigonius sp. n. (10) dorsal view of head; (11) ventral view of head; (12) fore tibia; (13) pronotum; (14) ventral view of prothorax; (15) dorsal view of pterothorax; (16) tube.

FIGURES 17 – 20. Terthrothrips trigonius sp. n. (17) abdominal sternites VI – IX of female; (18) abdominal sternites VI – IX of male; (19) pelta; (20) antenna.

FIGURES 21 – 24. Terthrothrips species. (21) T. levigatus sp. n. (female), (22) T. levigatus sp. n. (male); (23) T. trigonius sp. n. (female), (24) T. trigonius sp. n. (male).