Cloeon rubellum Navás, 1923

Figs 4 A – C, 7 A, B, 9 C, D, 11 C, D, 14 C, D, 16 C, D, 23 A – D, 24 A – F, 25 A – F, 27 B, 28 A, 29 E

Cloeon rubellum Navás, 1923: 3 (original description, male).

Cloeon rubellum: Lestage 1929: 99 (key to species). Hubbard and Pescador 1978: 92. Alba-Tercedor and Peters 1985: 221.

Material examined.

• 11 nymphs, 1 female imago, Bangkok Prov., Luang Suwannawajokkasikij 100 th Year Park, 13°50'54.5"N, 100°34'15.1"E, 1. VIII. 2024, C. Noenrimnong leg. (ZMKU) ; • 10 nymphs, 1 male subimago, 2 female subimagos, 7 male imagos, 2 female imagos, Bangkok Prov., Chalermprakiat 55 th Year Park, 13°51'17.0"N, 100°34'27.7"E, 1. VIII. 2024, C. Noenrimnong leg. (ZMKU) ; • 2 nymphs, Bangkok Prov., Varunawan Park, 13°50'51.1"N, 100°33'45.9"E, 25. X. 2024, B. Boonsoong & C. Noenrimnong leg. (ZMKU) ; • 4 male subimagos, 12 female subimagos, Bangkok Prov., Charn at the Avenue, 13°53'40.8"N, 100°33'27.8"E, 26. XI. 2024, S. Kwanboon leg. (ZMKU) ; • 3 nymphs, Bangkok Prov., Information Building 50 Years, 13°51'11.6"N, 100°34'11.9"E, 12. I. 2025, C. Noenrimnong leg. (ZMKU) ; • 3 nymphs, 4 male subimagos, 2 female subimagos, 1 male imago, 2 female imagos, Bangkok Prov., Emarica Academy, 13°50'39.8"N, 100°33'54.4"E, 2. II. 2025, S. Kwanboon & C. Noenrimnong leg. (ZMKU) ; • 2 female subimagos, Lop Buri Prov., Huai Som, 14°51'52.3"N, 100°51'28.1"E, 19. I. 2025, A. Wongyam leg. (ZMKU) ; • 2 nymphs, 18 male imagos, 10 female imagos, Chachoengsao Prov., Sao Cha-Ngok, 13°41'43.1"N, 101°09'13.5"E, 8. XI. 2024, B. Boonsoong leg. (ZMKU) ; • 2 nymphs, 1 male imago, Chanthaburi Prov., Laemsing, 12°29'05.0"N, 102°04'10.2"E, 29. XII. 2024, C. Noenrimnong leg. (ZMKU) ; • 2 male imagos, Nakhon Ratchasima Prov., Non Sung, 15°14'05.5"N, 102°22'40.6"E, 19. V. 2025, B. Boonsoong leg. (ZMKU) ; • 1 nymph, 1 male imago, Buri Ram Prov., Mafueang Phutthaisong, 15°29'54.0"N, 103°02'58.2"E, 16. V. 2025, B. Boonsoong leg. (ZMKU) ; • 3 nymphs, Khon Kaen Prov., Sithan Lake KKU, 16°26'41.1"N, 102°48'55.0"E, 1. IV. 2024, N. Tungpairojwong leg. (KKU) ; • 7 nymphs, Khon Kaen Prov., Fisheries Pond KKU, 16°27'31.5"N, 102°48'38.3"E, 1. IV. 2024, N. Tungpairojwong leg. (KKU) ; • 1 female imago, Chiang Mai Prov., Mae Jam, 18°29'47.8"N, 98°21'38.3"E, 15. XII. 2024, B. Boonsoong leg. (ZMKU) ; • 1 nymph, 1 male imago, Phetchaburi Prov., Centara Life Cha-Am Beach Resort, 12°44'03.3"N, 99°57'52.3"E, 3. VII. 2025, B. Boonsoong leg. (ZMKU) ; • 4 nymphs, Surat Thani Prov., Makham Tia Subdistrict, 9°06'32.9"N, 99°22'35.0"E, 1. X. 2025, S. Kwanboon leg. (ZMKU) .

Description

(in alcohol). Male imago (Fig. 7 B). See Navás (1923) (original description).

The male imagos of this species can be identified by their transparent wings (Fig. 11 D). The abdominal terga are translucent white, with the posterior margins of segments I – VII marked with brown pigmentation. Segments II and V bear central reddish-brown to purple spots, while segments III and VI possess prominent reddish-brown to purple stripes along the lateral margins. Segments VIII – X are brown to rust-coloured (Fig. 14 D). The abdominal sterna of segments VIII – IX and the posterior part of segment VII are white and lack distinct pigmentation (Figs 16 D, 23 B). The compound eyes are brown to rust-coloured, with olive-green lower portions (Fig. 9 D).

Female imago (Fig. 7 A): Body length 4.68–4.73 mm.

Head: Cream-white, with white to pale yellow midline flanked by two long orange to rust-coloured stripes covering the middle part of the head; upper margin white, with rust-coloured spots on the posterior part (Fig. 23 A).

Thorax: Cream-white, with white to pale yellow midline flanked by two narrow, long, orange to rust-coloured stripes that extend from the head, bordered on outer that by narrow white lines. Lateral margins of anterior thorax feature rust-coloured stripes. Posterior part has darker brown stripes, connecting with the patterns of the abdominal segments (Fig. 23 A).

Legs: Forelegs with femora that are predominantly rust-coloured (Fig. 9 C).

Abdominal terga: Cream-white, with reddish-brown to red patterns. Segments II to IX, anterior part with a pair of pale spots or drop-shaped stripes, without a pale midline. The lateral margins of each anterior segment with reddish-brown to purple spots or streaks, which are larger and more distinct on segments III and VI. Segments VII to IX have dark midline, while segment X is rust-coloured (Fig. 14 C).

Abdominal sterna: Cream-white with brittle white markings. Lateral margins at middle of sterna on segments II to VII with broad reddish-brown to red stripes along their entire length. Segments VI to IX with dark spots in the posterior part; posterior part of segment X is dark-coloured (Fig. 16 C).

Caudal filaments: Two caudal filaments transparent white with dark purple joints (Fig. 9 C).

Wings: Hyaline, with yellowish-golden veins and no dark bands. Pterostigmata area contains two straight veins (Fig. 11 C).

Mature nymphs (in alcohol): Body length 3.92–3.94 mm, terminal filaments 2.91–2.93 mm.

Head: Two rows of irregular brown spots (Fig. 4 A). Antennae mostly brown, with darker colouration at the base (Fig. 24 A).

Mouthparts: i). Mandibles: Molar area contains densely distributed molar teeth. Lateral margins with sparsely distributed hair-like setae. Large prostheca, inner incisors, and outer incisors (Fig. 24 B, C). ii). Labrum: Dorsal surface and half margins covered with hair-like setae. More than half of the surface contains sparsely distributed hair-like setae, with tufts of setae on either side of anterior notch (Fig. 24 D). iii). Maxillary Palp: Segments I and II with sparsely distributed hair-like setae on the surface, while segment III has more widely distributed hair-like setae (Fig. 24 E). iv). Labial Palpi: Segment I longer than segments II and III. Segments I and II with sparsely distributed hair-like setae, while segment III covered with hair-like setae that are longer and denser than those on other segments. Glossae with short setae along the margins, while paraglossae have longer setae on the margins (Fig. 24 F).

Thorax: irregular brown markings (Fig. 4 A).

Legs: Femora of all legs pale but with brown stripes near apex and base; short setae on surface and both margins. Tibiae and tarsi with brown bands near their bases, with short, sparsely distributed setae on the surface and dense, long setae along inner margins (Fig. 25 A – C). Base of claws (foreleg) expanded, with basal half containing two rows of spines with gradation size (Fig. 25 D).

Abdominal terga: Cream-white to pale brown. Segments III – IX, anterior part with very pale midline flanked by pair of pale spots or drop-shaped stripes. Segments II and III and V and VI may appear darker. Segments II and V (and occasionally III and VI) lack a pale midline, while segments IV and VII appear paler than other segments. Lateral margins of segments III and VI with large, prominent reddish-brown to purple stripes, similar to those of imago. Posterior half of lateral margins of segment VIII has four spines, while more than half of the lateral margin of segment IX has 5–6 spines (Figs 4 A, B, 25 E).

Abdominal sterna: Cream-white to pale brown, segments VI – IX with red to pale red spots in the posterior part (Fig. 4 C).

Caudal filaments: Each segment with a ring of spines at the joints. Cerci with long setae along inner margins and large, long spines on outer margins. Terminal filament shorter than the cerci and long setae along both margins (Figs 4 A, 25 F).

Egg. Width 64.15 μm; Height 94.66 μm; granules ranging from 0.068 –0.107 μm. Oval-shaped; surface covered with granules of varying irregular sizes and unevenly distributed across the surface (Fig. 23 C, D).

Distribution.

Northern Thailand (Chiang Mai province); northeastern Thailand (Buri Ram, Khon Kaen, and Nakhon Ratchasima provinces); central Thailand (Bangkok and Lop Buri provinces); eastern Thailand (Chachoengsao and Chanthaburi provinces); western Thailand (Phetchaburi province); southern Thailand (Surat Thani province).

Remarks.

The male imago of Cloeon rubellum was described by Navás (1923) based on materials from the Philippines. Ours is the first record of this species in Thailand. In this study, we provide the first description of the female imago, egg structure, and nymph of C. rubellum .