Cloeon viridulum Navás, 1931

Figs 5 A – C, 7 D, 12 A – D, 17 A – D, 26 A – D, 27 E, 28 D, 29 B

Cloeon viridulum Navás, 1931: 7, fig. 14 (original description, female subimago).

Cloeon viridulum: Navás 1933: 17. Wu 1935: 251. Ulmer 1936: 215. Gui 1985: 82. Alba-Tercedor and Peters 1985: 221. Sun et al. 2015: 58 (habitat). Si et al. 2017: 1 (transcriptome). Ying et al. 2021: 12 ( C. virens described by Ulmer (1925, 1936) was synonymised with C. viridulum).

Material examined.

• 2 female imagos, Nakhon Ratchasima Prov., Motorway M 6, 14°53'09.8"N, 101°37'17.5"E, 19. V. 2025, B. Boonsoong leg. (ZMKU) ; • 1 nymph, 3 male imagos, 2 female imagos, Kanchanaburi Prov., The River Kwai Bridge Resort, 14°02'26.7"N 99°30'26.6"E, 05. VII. 2025, B. Boonsoong leg. (ZMKU) .

Description

(in alcohol). Female subimago. See Navás (1931) (original description).

The female imagos are characterised by a green to yellowish-green head, with a pale-yellow midline flanked by two dark brown longitudinal stripes across the central region (Fig. 26 A). The thorax is yellowish-green, with a yellowish-green midline bordered by two narrow, long, pale brown longitudinal stripes extending from the head (Fig. 26 A). The abdominal terga are yellowish-green, with uniformly brown to dark reddish-brown pigmentation. Terga II – VIII have a pale midline flanked by a pair of pale spots or drop-shaped markings, while the lateral margins of each anterior segment bear dark reddish-brown spots or short stripes (Fig. 17 A). The abdominal sterna exhibit dark reddish-brown spots along the lateral margins of segments II – VIII (Fig. 17 C). The wings are hyaline, with yellowish-green to translucent yellow venation in the costal and subcostal areas (Fig. 12 C).

The mature nymphs possess a head with two rows of irregular brown spots (Fig. 5 A). The abdominal terga are dark green to brown, with uniformly dark brown to brown colouration. Terga II – IX bear a pale midline flanked by a pair of pale spots or drop-shaped marks. The abdominal sternum X lacks dark pigmentation (Fig. 5 C).

Male subimago (in alcohol). Body length 3.05–3.11 mm.

Head: Dark brown. Eyes orange to rust-coloured with olive green lower eyes (Fig. 12 B).

Thorax: Olive green to dark brown, with white to cream-white midline (Fig. 12 B).

Legs: White colouration (Fig. 12 B).

Abdominal terga: White; posterior parts of segments II – VI bear a pale pair of rust-coloured stripes. Lateral margins of segments II – VII anteriorly with dark reddish-purple spots or stripes. Segments VII – X rust-coloured (Fig. 17 B).

Abdominal sterna: White; lateral margins of segments II – VII anteriorly have dark reddish-purple spots or stripes. Segments VII – X white (Fig. 17 D).

Wings: Milky white, with cream-white veins and no dark bands. Posterior margin with sparse microtrichia (Fig. 12 D).

Egg. Width 49.78 μm; height 84.99 μm. Oval-shaped; surface covered with pits, with irregularly distributed depressions of varying sizes and irregular dimensions and unevenly distributed across the surface (Fig. 26 C, D).

Distribution.

Northeastern Thailand (Nakhon Ratchasima province); western Thailand (Kanchanaburi province).

Remarks.

The female subimago of Cloeon viridulum was described by Navás (1931) based on materials from China. Ours is the first record of this species in Thailand. In this study, we provide the first description of the male subimago and egg structure of C. viridulum .