taxonID	type	description	language	source
C6283AC318BA500DA29234AB9C79A09D.taxon	description	Figs 1 A – C, 6 A, B, 8 A, B, 10 A, B, 13 A, B, 15 A, B, 18 A – D, 19 A – F, 20 A – F, 27 C, 28 E, 29 D	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
C6283AC318BA500DA29234AB9C79A09D.taxon	description	Descriptions (in alcohol). Female imago (Fig. 6 A). See Kimmins (1947) for original description. The female imagos of this species can be distinguished by the pale green to yellowish-green head, which bears a pale green midline flanked by two dark brown longitudinal stripes covering most of the dorsal surface (Fig. 18 A). The thorax is similarly coloured, with a pale green to yellowish-green ground colour and a pale midline flanked by two continuous dark brown longitudinal stripes extending from the head to the abdomen (Fig. 18 A). The abdominal terga are green to yellowish-green, with dark brown to dark reddish-brown pigmentation. Terga II – IX have a pale midline flanked by a pair of pale spots or drop-shaped stripes; the lateral margins of anterior terga exhibit dark reddish-brown spots or short stripes, with those on segments III and VI extending almost to the lateral margins (Fig. 13 A). The abdominal sterna exhibit dark reddish-brown spots along the lateral margins of segments II – VIII (Fig. 15 A). The wings are hyaline, with dark brown venation in the costal and subcostal areas (Fig. 10 A). Male imago (Fig. 6 B). See Kimmins (1947) for original description. The male imagos are recognised by their orange-yellow compound eyes with olive-green lower portions (Fig. 8 B). The abdominal terga are translucent white, with segments III and VI bearing dark reddish-purple stripes extending nearly to the lateral margins; smaller paired stripes occur on segments II and V. Segments VIII – X are variably coloured from orange to dark brown (Fig. 13 B). The abdominal sterna of segments VIII and IX are white, while sternum X ranges from orange to dark brown (Figs 15 B, 18 B). The wings are hyaline (Fig. 10 B). Mature nymph (in alcohol): Body length 5.66 – 5.67 mm, terminal filaments 3.44 – 3.49 mm. Head: Two rows of irregular brown spots (Fig. 1 A). Antennae mostly brown, with darker colouration at the base (Fig. 19 A). Mouthparts: i). Mandibles: Molar area contains densely distributed molar teeth. Lateral margins have sparsely distributed hair-like setae. Large prostheca, inner incisors, and outer incisors (Fig. 19 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 the anterior notch (Fig. 19 D). iii). Maxillary Palp: Segments I and II with sparsely distributed hair-like setae on the surface, while segment III with more widely distributed hair-like setae (Fig. 19 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 with hair-like setae densely distributed around the terminal margin and longer and denser than those on other segments. Glossae and para-glossae with longer setae on the margins (Fig. 19 F). Thorax: Irregular brown markings (Fig. 1 A). Legs: Femora of all legs pale but with brown stripes near the apex and base, short setae on the surface and both margins. Tibiae and tarsi with brown bands near their bases, with short, sparsely distributed setae on the surface and dense, medium-sized setae along the inner margins (Fig. 20 A – C). Base of the claws (foreleg) expanded, with the basal half containing two rows of spines with gradation size (Fig. 20 D). Abdominal terga: Green to yellowish-green, uniform dark brown to dark reddish-brown. Segments II to IX, anterior part with a pale midline flanked by a pair of pale spots or drop-shaped stripes. Segments II and V may appear darker, while segments IV and VII may appear slightly paler but still retain the patterns. More than half of the lateral margin of segment VIII has 6 – 8 spines; whole of the lateral margin of segment IX has 6 – 11 spines (Figs 1 A, B, 20 E). Abdominal sterna: Green to yellowish-green, segments VII to IX with red to pale red spots near the middle posterior part, while segment X appears darker (Fig. 1 C). Caudal Filaments: Each segment has a ring of spines at joints. Cerci with long setae along the inner margins and large, long spines on the outer margins. Terminal filament shorter than cerci, and long setae along both margins (Figs 1 A, 20 F). Egg. Width 43.37 μm; height 68.12 μm; filament thickness ranging from 0.154 to 0.173 μm. Oval-shaped; surface uniformly covered with dense, long filamentous structures (Figs 18 C, D).	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
C6283AC318BA500DA29234AB9C79A09D.taxon	distribution	Distribution. Northern Thailand (Chiang Mai province); northeastern Thailand (Buri Ram, Khon Kaen, Maha Sarakham, Mukdahan, and Nakhon Ratchasima provinces); central Thailand (Bangkok and Lop Buri provinces); eastern Thailand (Chachoengsao and Prachin Buri provinces); western Thailand (Kanchanaburi and Ratchaburi provinces).	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
1E3B68F4D2F55FA7A80DE4506B763308.taxon	description	Figs 2 A – C, 7 C, 8 C, D, 10 C, D, 13 C, D, 15 C, D, 21 A – D, 27 D, 28 C, 29 C	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
1E3B68F4D2F55FA7A80DE4506B763308.taxon	description	Description (in alcohol). Female imago. See Kimmins (1947) for original description. The female imagos are characterised by a yellow head, with a pale-yellow midline flanked by two dark brown longitudinal stripes across the central region (Fig. 21 A). The thorax is yellow, with a yellow midline bordered by two narrow, long, pale brown longitudinal stripes extending from the head (Fig. 21 A). The abdominal terga are yellow, with uniformly brown to dark reddish-brown pigmentation. Terga II – IX 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 stripes (Fig. 13 C). The abdominal sterna display dark reddish-brown stripes along the lateral margins of segments II – VIII (Fig. 15 C). The wings are hyaline, with a pale-yellow stripe in the costal area and a dark brown stripe in the subcostal area (Fig. 10 C). Male imago (Fig. 7 C). See Kimmins (1947) for original description. The male imagos of this species can be identified by their hyaline wings (Fig. 10 D), which lack strong pigmentation except for a pale-yellow stripe in the costal area and a dark brown stripe in the subcostal area. The abdominal terga are translucent white, with segments II – VII showing similar patterns to those of the female but narrower, featuring faint reddish-brown spots along the lateral margins. Terga VIII – X are orange to dark orange in colouration (Fig. 13 D). The abdominal sterna of segments VIII – X are white and unpigmented (Figs 13 D, 15 D, 21 B). The compound eyes are orange to orange-yellow, with olive-green lower portions (Fig. 8 D). Nymph. See Ying et al. (2021) for first description. The mature nymphs possess a head with two rows of irregular brown spots (Fig. 2 A). The abdominal terga are dark green to brown, with uniformly dark brown to reddish-brown colouration. Terga II – IX bear a pale midline flanked by a pair of pale spots or drop-shaped marks. Segments II and V may appear darker, with interruptions in the midline, while segments IV and VII are comparatively paler (Fig. 2 A, B). The abdominal sternum X lacks dark pigmentation (Fig. 2 C). Egg. Width 71.61 μm; height 95.98 μm; granules ranging from 0.086 – 0.118 μm. Oval to nearly round; surface covered with granules of similar size, distributed unevenly. Some areas of surface appear smoother, with more widely spaced granules (Fig. 21 C, D).	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
1E3B68F4D2F55FA7A80DE4506B763308.taxon	distribution	Distribution. Northeastern Thailand (Buri Ram, Khon Kaen, Nakhon Ratchasima, Roi Et, and Ubon Ratchathani provinces); central Thailand (Bangkok, Lop Buri, and Nakhon Pathom provinces); eastern Thailand (Chachoengsao and Chanthaburi provinces).	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
6B344D073B7855828FAF82397AF0A599.taxon	description	Figs 3 A – C, 6 C, D, 9 A, B, 11 A, B, 14 A, B, 16 A, B, 22 A – D, 27 A, 28 B, 29 A	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
6B344D073B7855828FAF82397AF0A599.taxon	description	Description (in alcohol). Male imago (Fig. 6 D). See Kimmins (1947) for original description. The male imagos of this species can be identified by their transparent wings (Fig. 11 B), with distinct dark brown to black pigmentation in the pterostigma area and pale brown markings along the costal and subcostal regions. The abdominal terga are translucent white, with prominent reddish-brown markings on segments II, III and VI; segment VII has paler patterns, and segments VIII – IX are reddish brown (Fig. 14 B). The abdominal sterna of segments VIII – IX and the posterior portion of segment VII are white, marked with reddish-brown striped patterns (Figs 16 B, 22 B). The compound eyes are yellowish-brown with olive-green lower portions (Fig. 9 B). Female imago (Fig. 6 C). See Kimmins (1947) for original description. The female imagos can be distinguished by a cream-white head, bordered apically with a rust-coloured margin (Fig. 22 A). The thorax is cream-white, bearing a pair of midline dark brown stripes narrowing anteriorly and flanked by white lines (Fig. 22 A). The abdominal terga are cream-white, with prominent reddish-brown markings on segments II, III, and VI, and posterior parts of terga I – IX bearing a pair of reddish-brown stripes (Fig. 15 A). The abdominal sterna exhibit two reddish-brown longitudinal stripes along the abdomen that fuse apically (Fig. 16 A). The wings are hyaline, with clearly pigmented dark brown to black markings in the pterostigma area, and pale brown markings in the costal and subcostal regions (Fig. 11 A). Nymph. See Mukherjee et al. (2012) for first description and Ying et al. (2021). The mature nymphs resemble the imago in colouration. The head shows a similar pattern (Fig. 3 A), and abdominal terga bear reddish-brown markings on segments II, III, and VI, consistent with the adult stage (Figs 3 A, B). The abdominal sterna display two reddish-brown longitudinal stripes that merge on segments VIII – IX (Fig. 3 C). Egg. Width 59.82 μm; height 96.78 μm; granules ranging from 0.085 – 0.101 μm. Oval-shaped; surface covered with granules of consistent size and distribution, high density (Fig. 22 C, D).	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
6B344D073B7855828FAF82397AF0A599.taxon	distribution	Distribution. Northern Thailand (Chiang Mai province); northeastern Thailand (Khon Kaen and Ubon Ratchathani provinces); central Thailand (Bangkok, Lop Buri, and Nakhon Nayok, provinces); eastern Thailand (Chachoengsao province); western (Ratchaburi and Phetchaburi provinces); southern Thailand (Trang province).	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
38C6997C932D558BB0DACB682344E783.taxon	description	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	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
38C6997C932D558BB0DACB682344E783.taxon	description	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).	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
38C6997C932D558BB0DACB682344E783.taxon	distribution	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).	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
EF08435ED5E052639B18021773E0758D.taxon	description	Figs 5 A – C, 7 D, 12 A – D, 17 A – D, 26 A – D, 27 E, 28 D, 29 B	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
EF08435ED5E052639B18021773E0758D.taxon	description	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).	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
EF08435ED5E052639B18021773E0758D.taxon	distribution	Distribution. Northeastern Thailand (Nakhon Ratchasima province); western Thailand (Kanchanaburi province).	en	Noenrimnong, Chayanon, Suttinun, Chanaporn, Tungpairojwong, Nisarat, Boonsoong, Boonsatien (2026): Taxonomic insights into the diversity of Cloeon Leach, 1815 (Ephemeroptera, Baetidae) in Thailand. ZooKeys 1266: 1-39, DOI: 10.3897/zookeys.1266.176616
