taxonID	type	description	language	source
E57D87B7FFF4FFF4FF71FC687E2EFC38.taxon	description	Figures 1 – 2	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF4FFF4FF71FC687E2EFC38.taxon	materials_examined	Material examined: 4 nymphs, 1 ♀ imago, 1 ♂ imago, Wuying Forest Park, Fenglin County, Yichun City, Heilongjiang Province, 48.204776 ° N, 129.209142 ° E, ca. 300 m, 17 – 20. VII. 2024, Dewen Gong and Xuhongyi Zheng; 3 nymphs, 8 ♀ imagos, 2 ♂ imagos, 2 ♂ subimagos, Laocaohe, Mohe City, Daxinganling District, Heilongjiang Province, 52.833392 ° N, 122.591656 ° E, ca. 480 m, 16 – 19. VII. 2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun; 10 nymphs, 9 ♀ imagos, Dalin River, Mohe City, Daxinganling District, Heilongjiang Province, 52.968586 ° N, 122.269555 ° E, ca. 470 m, 16 – 19. VII. 2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF4FFF4FF71FC687E2EFC38.taxon	description	Description: see Kluge (1985, adult), Hwang & Bae (2001, nymph) and Bauernfeind & Soldán (2012, nymph and subimago).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF4FFF4FF71FC687E2EFC38.taxon	distribution	Distribution: China (Heilongjiang Province); Korea; Russia; Mongolia.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF4FFF4FF71FC687E2EFC38.taxon	diagnosis	Diagnosis Mature nymph: body length ranges from 13.0 to 15.0 mm, wingpads without spots (Figs 1 A, B). Length ratio of first segment of maxillary palp to galea-lacinia 1.0: 1.0, inner margin of maxillary palp segment II straight (Fig. 1 C). Posterolateral spines on terga I – IX gradually larger from anterior to posterior, length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 4.0 (Figs 1 D – F). Each abdominal sternum with inverted U-shaped marking (Fig. 1 B). Posterior margin of abdominal sternum IX slightly convex (Figs 1 E, F). Both dorsal surface and posterior margin of tergum X with stout and pointed spine-like setae, lateral margins lack (Fig. 1 G). Outer margins of dorsal and ventral lamellae of both gills I and II concave, costal rib of dorsal lamella in gill II shorter than half of anterior margin (Figs 1 H, I). Outer and posterior margins of gill III concave (Fig. 1 J). Proximal plate of gill VII well developed (Fig. 1 K).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF4FFF4FF71FC687E2EFC38.taxon	description	Male imago: Body length 16.0 – 18.0 mm, wings transparent. Forelegs entirely brown, midlegs and hindlegs entirely yellowish (Figs 2 A – C). Each abdominal sternum with an inverted U-shaped marking, posterolateral spines of abdominal segments VIII and IX relatively small (Figs 2 D – G). Inner margin of basal segment of forceps with projection, length of penis subequal to styliger (Figs 2 D, E). Dorsal elongation of penis curved with enlarged base and outer margin with about 3 small spines basally, dorsal sclerotized transverse band of penis without expansion, two penis lobes distinctly separated, each with concave tip, ventral side with translucent membranous projection, inner margin with 4 – 6 small spines, outer margin concave (Figs 2 H – J). Female imago: Body length 15.0 – 17.0 mm, wings transparent. Color pattern similar to male. Each abdominal sternum with inverted U-shaped marking (Fig. 2 K); sternum VII extended posteriorly into triangular lobe, sternum VIII with pair of depressed funnel-shaped sclerotized line (Fig. 2 L).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF4FFF4FF71FC687E2EFC38.taxon	discussion	Remarks. The male genitalia of this species are similar to those of S. immanis because of elongated penal lobe. However, both nymph and adults of them possess distinct diagnostic characteristics. The morphological differences in mature nymph are: (1) this species is significantly smaller than S. immanis; (2) posterior margin of abdominal sternum IX in this species is slightly convex (Figs 1 E, F), whereas in S. immanis, it is relatively straight; (3) posterolateral spines of abdominal sterna in this species are relatively small, with a length ratio of spine to sternum of 1.0: 4.0 (Figs 1 D – F). In contrast, posterolateral spines in S. immanis are larger, with a length ratio to sternum of 1.0: 2.0. The diagnostic characteristics of male adults mainly differ in: (1) in this species, the dorsal elongation of penis is curved, with an expanded base and approximately three small spines on outer margin (Fig. 2 J). In contrast, dorsal elongation of penis in S. immanis is slender and smooth, lacking spines; (2) posterolateral spines of abdominal terga VIII and IX in this species are relatively small (Figs 2 D, E), whereas in S. immanis, these spines are highly developed, being broad and sharply pointed. Nymph of this species is almost identical in all characteristics to that of S. zhelochovtsevi, except for the maxillary palps (see remarks section of S. zhelochovtsevi).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF7FFF9FF71FB847CFEFB62.taxon	description	Figures 3 – 4	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF7FFF9FF71FB847CFEFB62.taxon	materials_examined	Material examined: 65 nymphs, 3 ♀ imagos, 1 ♂ imago, Jiuzhaigou Valley Scenic and Historic Interest Area, Aba Tibetan and Qiang Autonomous Prefecture, Sichuan Province, 33.159 ° N, 103.901 ° E, ca. 2400 m, 6 – 7. VII. 2013, Beixing Wang, Yun He, and Guangba Li; 130 nymphs, Jiuzhaigou Valley Scenic and Historic Interest Area, Aba Tibetan and Qiang Autonomous Prefecture, Sichuan Province, 33.159 ° N, 103.901 ° E, ca. 2400 m, 9 – 12. VII. 2019, Beixing Wang, Xinyu Ge, and Yu Wang; 1 ♀ imago, 1 ♂ imago, Jiuzhaigou Valley Scenic and Historic Interest Area, Aba Tibetan and Qiang Autonomous Prefecture, Sichuan Province, 33.1715 ° N, 103.52108 ° E, ca. 2400 m, 6. VII. 2023, Mengyao Li.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF7FFF9FF71FB847CFEFB62.taxon	description	Description: see Han et al. (2016).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF7FFF9FF71FB847CFEFB62.taxon	distribution	Distribution: China (Sichuan).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF7FFF9FF71FB847CFEFB62.taxon	diagnosis	Diagnosis Mature nymph: Body length 13.0 – 17.0 mm, wingpads with spots (Figs 3 A, B). Length ratio of first segment of maxillary palp to galea-lacinia about 1.0: 1.0, inner margin of maxillary palp segment II straight (Fig. 3 C). Posterolateral spines on terga I – IX gradually larger from anterior to posterior, length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 2.0 (Figs 3 D – F). Each abdominal sternum with pair of fused reddish-brown oblique stripes (Fig. 3 B). Posterior margin of abdominal sternum IX distinctly convex (Figs 3 E, F). Both dorsal surface and margins of tergum X with stout and pointed spine-like setae (Fig. 3 G). Outer margins of dorsal lamellae of both gills I and II straight while those of ventral lamellae concave, costal rib of dorsal lamella in gill II longer than half of anterior margin (Figs 3 H, I). Outer and posterior margins of gill III straight, proximal plate of gill VII well developed (Figs 3 J, K).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF7FFF9FF71FB847CFEFB62.taxon	description	Male imago: Body length 13.0 – 16.0 mm, forewing with dark brown crossveins and large dark brown spots between C and Rs 1, distal half of hindwing light brown with a spot near middle of R 1 and a brown stripe near forking point of MA. Forelegs entirely brown, midlegs and hindlegs entirely light brown (Figs 4 A – C). Anterior and lateral margins of each abdominal sternum darker (Fig. 4 D). Posterolateral spines of abdominal segments VIII and IX relatively small (Figs 4 D – G). Inner margin of basal segment of forceps without projection, length of penis subequal to styliger (Figs 4 F, G). Dorsal elongation of penis straight and spineless with sclerotized outer margin, dorsal sclerotized transverse band of penis without expansion, each penis lobe tip with brown sclerotized plates, length of two penis lobes ca. 1.1 x width (Figs 4 H, I). Female imago: Body length 15.0 – 16.0 mm, wings with brown stripe and dots. Color pattern similar to male. Sternum VII extended posteriorly into a rectangular lobe, sternum VIII with a pair of reddish-brown stripe (Fig. 4 J).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFF7FFF9FF71FB847CFEFB62.taxon	discussion	Remarks For morphological comparison of three closely related species (S. davidi, S. dongxi, and S. orientalis sp. nov.) see remarks of S. orientalis sp. nov. Three diagnostic characteristics proposed by Yang et al. (2023) for distinguishing between S. dongxi and S. davidi appear to be problematic: (1) Sclerotization of penis lobe: Yang et al. (2023) proposed that two elongations on transverse sclerite of penis lobes could serve as a diagnostic feature for male S. dongxi. However, further observations reveal that dorsal sclerotization pattern of penis lobes is similar across all three species (S. davidi, S. dongxi, and S. orientalis sp. nov.). This pattern includes a pair of rounded sclerotized plates and a medially convex transverse sclerotized band, and each rounded plate with a small apical elongation (Fig. 4 H); (2) Posterolateral spines on tergum IX in male adults: While Yang et al. (2023) proposed that male imagos of S. dongxi can be distinguished from S. davidi by well-developed posterolateral spines on tergum IX, our observations indicate that all three species (S. dongxi, S. davidi, and S. orientalis sp. nov.) exhibit relatively small spines compared to S. immanis. (3) Posterolateral spines on terga in nymph: Yang et al. (2023) stated that posterolateral spines on the terga of S. dongxi nymph are restricted to segments II – IX, but this may require reconsideration. All reported Siphlonurus nymph in China possess posterolateral spines on abdominal terga I – IX. Additionally, posterolateral spines of these three species (S. davidi, S. dongxi, and S. orientalis sp. nov.) are relatively large, with a spine-to-tergum IX length ratio of approximately 1.0: 2.0.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFAFFFEFF71FAB87E27FEC8.taxon	description	Figures 5 – 6	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFAFFFEFF71FAB87E27FEC8.taxon	materials_examined	Material examined: 2 nymphs, 1 ♀ imago, 1 ♂ imago, 1 ♀ subimago, 1 ♂ subimago, two exuviae of nymphs, Shangri La, Diqing Prefecture, Yunnan Province, 17. VI. 2022, Xianfu Li.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFAFFFEFF71FAB87E27FEC8.taxon	description	Description: see Yang et al. (2023).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFAFFFEFF71FAB87E27FEC8.taxon	distribution	Distribution: China (Yunnan Province).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFAFFFEFF71FAB87E27FEC8.taxon	diagnosis	Diagnosis Mature nymph: Body length 14.0 – 17.0 mm, wingpads with spots (Figs 5 A, B). Length ratio of first segment of maxillary palp to galea-lacinia about 1.0: 1.3, inner margin of maxillary palp segment II straight (Fig. 5 C). Posterolateral spines on terga I – IX gradually larger from anterior to posterior, length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 2.0 (Figs 5 D – F). Each abdominal sternum with two pairs of spots, smaller pair located centrally and larger pair located at posterior corners, small and large spots often fused (Fig. 5 B). Posterior margin of abdominal sternum IX distinctly convex (Figs 5 E, F). Both dorsal surface and margins of tergum X with stout and pointed spine-like setae (Fig. 5 G). Outer margins of dorsal and ventral lamellae of both gills I and II straight, costal rib of dorsal lamella in gill II longer than half of anterior margin (Figs 5 H, I). Outer and posterior margins of gill III straight, proximal plate of gill VII well developed (Figs 5 J, K).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFAFFFEFF71FAB87E27FEC8.taxon	description	Male imago: Body length 17.5 mm, forewing with dark brown crossveins and large dark brown spots between C and Rs 1, distal half of hindwing light brown with spot near middle of R 1 and brown stripe near forking point of MA. All legs generally pale yellow, but ends of femur, tibia, and each tarsal segment noticeably darker, appearing brown (Figs 6 A – C). Each sternum with pair of dark brown stripes near center, each stripe consisting of central spot and large spot at posterior corner (Fig. 6 D). Posterolateral spines of abdominal segments VIII and IX relatively small. Inner margin of basal segment of forceps with projection, penis longer than styliger (Figs 6 E – G). Dorsal elongation of penis straight, spineless, and entirely sclerotized, dorsal sclerotized transverse band of penis without expansion, inner margin of each penis lobe with brown groove, length of two penis lobes ca. 1.2 x width (Figs 6 H, I). Female imago: Body length 17.0 mm, wings with brown stripe and dots. Color pattern similar to male. Sternum VII extended posteriorly into rectangular lobe, sternum VIII with pair of brown stripe (Fig. 6 J).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFAFFFEFF71FAB87E27FEC8.taxon	discussion	Remarks: For morphological comparison of three closely related species (S. davidi, S. dongxi, and S. orientalis sp. nov.) see remarks of S. davidi and S. orientalis sp. nov.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFDFFFEFF71FED47DF0F8B4.taxon	description	Figures 7 – 8	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFDFFFEFF71FED47DF0F8B4.taxon	materials_examined	Material examined: 15 nymphs, Sanbao Village, Songfengshan Town, Acheng District, Harbin City, Heilongjiang Province, 1. IV. 2023, Qiang Dong; 200 nymphs, 20 nymph exuviae, Erdaohzi, Sanbao Village, Songfeng Mountain Town, Acheng District, Harbin City, Heilongjiang Province, 45.245339 ° N, 127.263786 ° E, ca. 260 m, 27 – 28. IV. 2024, Xinhe Qiang, Muhe Deng, and Mengyao Li; 5 nymphs, Dashihe, Xinxing Village, Acheng District, Harbin City, Heilongjiang Province, 45.233113 ° N, 127.154525 ° E, ca. 370 m, 29. IV. 2024, Xinhe Qiang, Muhe Deng, and Mengyao Li; 3 nymphs, Tangwanghe, Haolianghe Town, Nancha District, Yichun City, Heilongjiang Province, 46.431801 ° N, 129.374393 ° E, ca. 110 m, 4. V. 2024, Xinhe Qiang, Muhe Deng, and Mengyao Li; 100 nymphs, 50 nymph exuviae, 60 ♀ imagos, 28 ♂ imagos, Erdaohzi, Sanbao Village, Songfeng Mountain Town, Acheng District, Harbin City, Heilongjiang Province, 45.245339 ° N, 127.263786 ° E, ca. 260 m, 23 – 29. V. 2024, Xinhe Qiang and Xiaofang Chen.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFDFFFEFF71FED47DF0F8B4.taxon	description	Description: see Kluge (1985, adult and nymph) and Hwang & Bae (2001, nymph).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFDFFFEFF71FED47DF0F8B4.taxon	distribution	Distribution: China (Heilongjiang Province); Korea; Russia; Mongolia.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFDFFFEFF71FED47DF0F8B4.taxon	diagnosis	Diagnosis Mature nymph: Body length 18.0 – 25.0 mm, wingpads without spots (Figs 7 A, B). Length ratio of first segment of maxillary palp to galea-lacinia about 1.0: 1.0, inner margin of maxillary palp segment II straight (Fig. 7 C). Posterolateral spines on terga I – IX gradually larger from anterior to posterior, length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 2.0 (Figs 7 D – F). Each abdominal sternum with inverted U-shaped marking (Fig. 7 B). Posterior margin of abdominal sternum IX nearly straight (Figs 7 E, F). Dorsal surface and posterior margin of tergum X with stout and pointed spine-like setae, lateral margins lack (Fig. 7 G). Outer margins of dorsal and ventral lamellae of both gills I and II concave, costal rib of dorsal lamella in gill II shorter than half of anterior margin (Figs 7 H, I). Outer and posterior margins of gill III concave, proximal plate of gill VII well developed (Figs 7 J, K).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFDFFFEFF71FED47DF0F8B4.taxon	description	Male imago: Body length 20.5 – 22.0 mm, all legs brown (Fig. 8 A), wings transparent (Figs 8 C, D). Posterolateral spines of abdominal segments VIII and IX relatively large (Fig. 8 E, F). Each abdominal sternum with inverted Ushaped marking (Fig. 8 F). Inner margin of basal segment of forceps with projection, length of penis subequal to styliger (Figs 8 G, H). Dorsal elongation of penis slender and spineless, dorsal sclerotized transverse band of penis without expansion, two penis lobes separated, each tip bifurcated, outer bifurcation distinctly sclerotized, ventral side with a translucent membranous structure, inner margin of each penis lobe with 4 – 6 small spines basally, outer margin concave near the middle (Figs 8 I, J). Female imago: Body length 27.0 – 29.0 mm, wings transparent (Fig. 8 B). Color pattern similar to male (Fig. 8 K). Sternum VII extended posteriorly into a triangular lobe, sternum VIII with W-shaped dark brown sclerotized line (Fig. 8 L).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFFDFFFEFF71FED47DF0F8B4.taxon	discussion	Remarks: This species is close to S. chankae. The detailed comparison is presented in the remarks of S. chankae.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFE0FFE3FF71FF2D7FE4F9AC.taxon	description	Figures 9 – 10	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFE0FFE3FF71FF2D7FE4F9AC.taxon	materials_examined	Material examined: 3 nymphs, Xingan National Forest Park, Yichun City, Heilongjiang Province, 13 – 14. VII. 2016, Juan Yan Luo, Wei Zhang, and Ze Hu; 1 nymph, Laocaohe, Mohe City, Daxinganling District, Heilongjiang Province, 52.833392 ° N, 122.591656 ° E, ca. 480 m, 16 – 19. VII. 2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun; 3 nymphs, 2 ♀ imagos, 1 ♂ imago, Wuying Forest Park, Fenglin County, Yichun City, Heilongjiang Province, 48.204776 ° N, 129.209142 ° E, ca. 300 m, 17 – 20. VII. 2024, Dewen Gong and Xuhongyi Zheng; 1 ♀ imago, ♂ imago, Liujiazi, Gaoleng Town, Fangzheng County, Harbin City, Heilongjiang Province, 45.731443 ° N, 129.290088 ° E, ca. 330 m, 21 – 22. VII. 2024, Dewen Gong and Xuhongyi Zheng.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFE0FFE3FF71FF2D7FE4F9AC.taxon	description	Description: see Bauernfeind & Soldán (2012), Studemann et al. (1988) and Gaino & Rebora (2001).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFE0FFE3FF71FF2D7FE4F9AC.taxon	distribution	Distribution: The species is found throughout the Palaearctic region, but it is the first record from China here. It is found in Heilongjiang Province.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFE0FFE3FF71FF2D7FE4F9AC.taxon	diagnosis	Diagnosis Mature nymph: Body length 14.0 – 16.0 mm, wingpads without spots (Figs 9 A, B). Length ratio of first segment of maxillary palp to galea-lacinia about 1.0: 0.9, inner margin of maxillary palp segment II straight (Fig. 9 C). Posterolateral spines on terga I – IX gradually larger from anterior to posterior, length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 3.0 (Figs 9 D, E). Each abdominal sternum with an inverted U-shaped marking (Fig. 9 B). Posterior margin of abdominal sternum IX slightly convex (Fig. 9 E). Dorsal surface and posterior margin of tergum X with stout and pointed spine-like setae, lateral margins lack (Fig. 9 F). Outer margins of dorsal and ventral lamellae of both gills I and II concave, costal rib of dorsal lamella in gill II shorter than half of anterior margin (Figs 9 G, H). Outer and posterior margins of gill III concave, proximal plate of gill VII well developed (Figs 9 I, J).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFE0FFE3FF71FF2D7FE4F9AC.taxon	description	Male imago: Body length 11.5 – 15.0 mm, wings transparent, all legs generally light brown (Figs 10 A – C). Posterolateral spines of abdominal segments VIII and IX relatively small (Figs 10 D – G). Each abdominal sternum with an inverted U-shaped marking (Fig. 10 F). Inner margin of basal segment of forceps with a projection, length of penis subequal to styliger (Figs 10 D, E). Dorsal elongation of penis short, sharp, and spineless, dorsal sclerotized transverse band of penis expanded in the middle, inner margin of each penis lobe with 5 – 6 long spines, outer margin with approximately four small spines, each penis lobe with a short and wide projection posterolaterally (Figs 10 H – J). Female imago: Body length 13.0 – 15.0 mm, wings transparent. Color pattern similar to male (Fig. 10 K). Sternum VII extended posteriorly into a triangular lobe, sternum VIII with funnel-shaped dark brown sclerotized line (Fig. 10 L).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFE0FFE3FF71FF2D7FE4F9AC.taxon	discussion	Remarks: see remarks of S. polyspineus sp. nov.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFE3FFE0FF71FF2D7C99FE20.taxon	description	Figures 11 – 17	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFE3FFE0FF71FF2D7C99FE20.taxon	materials_examined	Material examined Holotype: male imago, Chanyuan Temple, Tianmu Mountain, Zhejiang Province, 3 – 5. IV. 2019, Heying Wang, Xiaoli Ying, Wei Zhang and Zhenxing Ma. Paratypes: 50 nymphs, 2 ♀ imagos, 6 ♂ imagos, 1 ♀ subimago, 1 ♂ subimago, 10 exuviae of nymphs, with same label data as holotype.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFECFFECFF71FBD97EC2F898.taxon	description	Figures 18 – 19	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFECFFECFF71FBD97EC2F898.taxon	materials_examined	Material examined: 21 ♀ imagos, 6 ♂ imagos, Weihe Yulin Forest Farm, Shangzhi City, Heilongjiang Province, 8 – 16. VII. 1993, Youwen Li and Changhai Sun; 7 nymphs, 60 ♀ imagos, Yalu River, Bugt Town, Yakeshi City, Inner Mongolia, 48.44625 ° N, 121.54724 ° E, ca. 670 m, 2 – 4. VIII. 2007, Changfa Zhou, Hui Xie, and Shilei Wang; 3 nymphs, 10 ♀ imagos, Jiliu River, Mangui Town, Genhe City, Inner Mongolia, 52.02925 ° N, 122.02733 ° E, ca. 630 m, 12. VIII. 2007, Shilei Wang and Hui Xie; 1 nymph, 2 ♀ imagos, Erdao Baihe Town, Fusong County, Jilin Province, 23 – 25. VII. 2008, Shilei Wang and Guo Zhao; 2 nymphs, Changbai Mountain, Manjiang Town, Fusong County, Jilin Province, 41.9485 ° N, 127.5907 ° E, 10. VIII. 2022, Xuhongyi Zheng; 5 ♀ imagos, Badaohe, Guanmen Mountain, Benxi City, Liaoning Province, 41.146595 ° N, 124.148296 ° E, ca. 300 m, 20 – 24. VII. 2023, Shuang Qiu and Xinye Liu; 2 ♀ imagos, Laocaohe, Mohe City, Daxinganling District, Heilongjiang Province, 52.833392 ° N, 122.591656 ° E, ca. 480 m, 16 – 19. VII. 2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFECFFECFF71FBD97EC2F898.taxon	description	Description: see Kluge (1982) and Hwang & Bae (2001).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFECFFECFF71FBD97EC2F898.taxon	distribution	Distribution: China (Heilongjiang Province, Jilin Province, Inner Mongolia); Russia, Korea; Mongolia.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFECFFECFF71FBD97EC2F898.taxon	diagnosis	Diagnosis Mature nymph: The body length 13.0 – 15.0 mm, wingpads with spots (Figs 18 A, B). Length ratio of first segment of maxillary palp to galea-lacinia about 1.0: 1.0, inner margin of maxillary palp segment II convex apically (Fig. 18 C). Posterolateral spines on terga I – IX gradually larger from anterior to posterior, length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 4.0 (Figs 18 D, E). Each abdominal sternum with an inverted U-shaped marking (Fig. 18 B). Posterior margin of abdominal sternum IX slightly convex (Fig. 18 E). Dorsal surface and posterior margin of tergum X with stout and pointed spine-like setae, lateral margins lack (Fig. 18 F). Outer margins of dorsal and ventral lamellae of both gills I and II straight, costal rib of dorsal lamella in gill II shorter than half of anterior margin (Figs 18 G, H). Outer and posterior margins of gill III straight, proximal plate of gill VII well developed (Figs 18 I, J).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFECFFECFF71FBD97EC2F898.taxon	description	Male imago: Body length 12.0 – 13.0 mm, all crossveins of forewing dark brown, with long dark brown stripe near middle of both forewing and hindwing. Forelegs entirely brown, midlegs and hindlegs entirely light brown (Figs 19 A – C). Each abdominal sternum with inverted U-shaped marking (Fig. 19 D). Posterolateral spines of abdominal segments VIII and IX relatively small (Figs 19 E, F). Inner margin of basal segment of forceps with projection, length of penis subequal to styliger (Figs 19 E, F). Dorsal elongation of penis wide and arched with few spines apically (approximately 2 – 3 spines), dorsal sclerotized transverse band of penis without expansion, each penis lobe distinctly sclerotized, apex densely covered with spines (approximately 12 – 14 spines), additional long and slender projection between dorsal elongation and each penis lobe, tip of this projection with two spines (Figs 19 G – I). Female imago: Body length 13.0 – 14.0 mm, wings with brown stripe. Color pattern similar to male. Sternum VII extended posteriorly into a rectangular lobe, medially concave. Sternum VIII with a pair of funnel-like sclerotized line (Fig. 19 J).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFECFFECFF71FBD97EC2F898.taxon	discussion	Remarks Among Siphlonurus species reported in China, only four species (S. davidi, S. dongxi, S. orientalis sp. nov., and S. palaearcticus) exhibit wing pigmentation in their adult stage. Among them, S. davidi, S. dongxi, and S. orientalis sp. nov. share a similar wing pigmentation pattern: forewing with dark brown crossveins and large dark brown spots between C and Rs 1; distal half of hindwing light brown, with a spot near middle of R 1 and a brown stripe near forking point of MA (Figs 4 B, C, 6 B, C, 14 B, C), while S. palaearcticus displays a distinctly different pattern: all crossveins of forewing are dark brown, with dark brown stripes near middle of both forewing and hindwing (Figs 19 B, C), making it easily distinguishable. Additionally, penis lobe structure of S. palaearcticus is highly unique, featuring an additional slender projection between dorsal elongation and penis lobe, with two spines at its apex (Fig. 19 G), which is a characteristic not observed in other Chinese Siphlonurus species. In terms of nymphal morphology, S. palaearcticus combines characteristics of both northern-distributed species (S. chankae, S. immanis, S. lacustris, S. polyspineus sp. nov., and S. zhelochovtsevi) and southern-distributed species (S. davidi, S. dongxi, and S. orientalis sp. nov.). For example, each abdominal sternum of S. palaearcticus bears an inverted U-shaped marking (Fig. 18 B), lateral margins of tergum X lack stout spine-like setae (Fig. 18 F), and costal rib of dorsal lamella in gill II is shorter than half of anterior margin (Fig. 18 H) – features aligning with those of northern-distributed species. On the other hand, outer margins of dorsal lamellae of gills I and II are straight, and outer and posterior margins of gill III are also straight (Figs 18 G – I) – traits resembling those of southern-distributed species. Additionally, S. binotatus is likely not distributed in China at present, as this species is currently known only from Japan. The S. binotatus reported by Imanishi (1940) is likely S. palaearcticus. The nymphs of Siphlonurus species are difficult to distinguish morphologically, and both S. binotatus and S. palaearcticus have pigmented wingpads, which can easily lead to mis-identification. Therefore, Imanishi (1940) reported S. palaearcticus in China, while we tentatively exclude S. binotatus from the Chinese fauna.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD0FFDBFF71FF2D7E32FA30.taxon	description	Figures 20 – 26	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD0FFDBFF71FF2D7E32FA30.taxon	materials_examined	Material examined Holotype: male imago, Laocaohe, Mohe City, Daxinganling District, Heilongjiang Province, 52.833392 ° N, 122.591656 ° E, ca. 480 m, 16 – 19. VII. 2024, Xinhe Qiang, Ningning Wang and Yuxian Sun. Paratypes: 5 nymphs, 8 ♀ imagos, 2 ♂ imagos, 2 ♀ subimagos, 3 ♂ subimagos, with same label data as holotype. Additional materials: 10 ♀ imagos, 3 ♂ imagos, Yalu River, Bugt Town, Yakeshi City, Inner Mongolia, 48.44625 ° N, 121.54724 ° E, ca. 670 m, 2. VIII. 2007, Changfa Zhou, Hui Xie, and Shilei Wang; 15 ♀ imagos, Chaor River, Tarqi Town, Yakeshan City, Inner Mongolia, 47.58584 ° N, 121.11288 ° E, ca. 760 m, 3. VIII. 2007, Changfa Zhou, Hui Xie, and Shilei Wang; 50 nymphs, 20 ♀ imagos, Gen River, Genhe City, Inner Mongolia, 50.46255 ° N, 121.31191 ° E, ca. 700 m, 9 – 10. VIII. 2007, Changfa Zhou, Hui Xie, and Shilei Wang; 2 ♀ imagos, Genhe, Hexi Street, Genhe City, Hulunbuir City, Inner Mongolia Autonomous Region, 50.796106 ° N, 121.578682 ° E, ca. 720 m, 19. VII. 2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD0FFDBFF71FF2D7E32FA30.taxon	description	Description Mature nymph (in alcohol, Figs 20 – 22): Body length 11.0 – 13.0 mm, cerci 5.0 – 6.0 mm, length of terminal filament nearly subequal to cerci. Body generally yellowish to amber, legs with distinct dark brown bands (Figs 20 A, B). Head: generally yellowish with pair of longitudinal dark brown stripe on vertex. Clypeus dark brown. Compound eyes dark grey. Antennae 1.0 mm, length of antennae subequal to length of head. Mouthparts: totally yellowish. Galea-lacinia and apical segment of maxillary palp dark brown. Labrum: free margin with row of dense bristle-like setae, additional row of setae near anterior margin dorsally. Ventral surface scattered with short dense bristle-like setae, forming an obvious median groove. Posterolateral corner slightly sclerotized. Length-to-width ratio about 1.0: 2.0 (Fig. 21 A). Left mandible: apex of outer incisor divided into three denticles and inner one divided into two denticles, outer incisor wider than inner one. Prostheca composed of distinct stout spine and a tuft of numerous spines (Fig. 21 B). Right mandible: apex of outer and inner incisors serrated into two denticles respectively. Prostheca constituted by tuft of spines and small spine. An additional tuft of hair-like setae on inner margin near molar (Fig. 21 C). Lingua of Hypopharynx round, apical surface with dense short setae. Superlinguae with hair-like setae on apical and lateral margins (Fig. 21 D). Maxillae: Apex of galea-lacinia divided into three broad canines. Apical margin of galea-lacinia with row of long setae. Inner margin with two rows of dense long setae and three stout apical dentisetae between them, two obvious dentisetae slightly longer than setae nearby. Three segments of maxillary palp with sparse setae on surface. Length of basal segment distinctly subequal to length of galea-lacinia, inner margin of maxillary palp segment II straight, length ratio of three segments ca. 1.0: 0.8: 0.5 (Figs 21 E, F). Labium: glossae and paraglossae with dense bristle-like setae on surface, paraglossae semi-circle and broader than glossae. Three segments of labial palp with sparse setae and spines on surface, inner margin of segment III slightly concave, length ratio of three segments from basal to apical ca. 1.0: 0.6: 0.5 (Figs 21 G, H). Thorax: nota totally yellowish with symmetric irregular variable spots, wingpads without spots (Fig. 20 A). Coloration pattern of all legs similar, ground color yellowish, tarsi dark apically and basally. Surface of all legs with short sparse spines and setae (Figs 22 A – C). Claws slim and pointed, without teeth (Fig. 22 D). Length ratio of femora: tibiae: tarsus in all legs similar, ca. 1.7: 1.0: 1.1. Abdomen: Each abdominal terga with pair of dark spots in middle. Each sternum with inverted U-shaped marking (Fig. 20 B). Posterolateral projection of each tergum well developed, progressively larger and wider from tergum I to tergum IX, length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 4.0 (Figs 20 C – E). Abdominal sternum IX of both sexes with slightly convex posterior margin (Figs 20 D, E). Dorsal surface and posterior margins of abdominal terga I – IX covered with stout spine-like setae, while ventral surface and posterior margins of abdominal sterna I – IX with smaller, more sparse spine-like setae (Figs 20 A – B). Dorsal surface and posterior margin of tergum X with sparse stout and pointed spine-like setae; lateral margins lack (Fig. 20 F). Gills transparent and with distinct brown trachea, dorsal lamellae of gills I and II, along with the other five gills, with sclerotized ribs on the anterior margin and near the middle (Figs 22 E – K). Gills I and II similar in size and shape, outer margins of dorsal and ventral lamellae of both gills I and II concave. Costal rib of dorsal lamella in gill II shorter than half of anterior margin (Figs 22 E, F). Outer and posterior margins of gill III concave. Proximal plate of gill VII poorly developed (Figs 22 G, K). Caudal filaments yellowish with two dark brown band subapically and apically. Mesal margins of cerci and both sides of terminal filament with dense hair-like setae (Fig. 20 A, B). Male imago (in alcohol, Figs 23 – 24): body length 13.0 – 15.0 mm, cerci 13.0 – 15.0 mm, terminal filament 0.1 mm, forewing 9.0 – 10.0 mm, hindwing 4.0 – 5.0 mm, antennae 0.8 mm. General coloration brown and amber, wings transparent (Figs 23 A – C). Head: Compound eyes contiguous and grey, ocelli pale with dark base. Antennae light brown with darker scape and pedicle. Thorax: general coloration dark brown. Posterior projection of mesonotum and metanotum distinctly convex (Fig. 23 A). Wings: transparent. In forewing, Rs forked at 1 / 3 basal, MA forked near middle, MP forked at very base, near the forking point of Rs and MA. Rs and MA fused near base, stem of them further fused with MP. CuA slightly curved backwards, ended at outer margin before tornus, six small veins connecting CuA to hind margin. CuP attached at midpoint of hind margin. In hindwing, MA forked at apical 1 / 3, MP forked at basal 1 / 3 (Figs 23 B, C). Legs: coxae of all legs dark brown, all legs generally whitish, without distinct markings. Each leg with two claws, acute and hooked (Figs 24 A – D). Length ratio of femur, tibia and tarsal segments I – V of foreleg = 3.6: 3.4: 1.4: 2.2: 2.1: 1.3: 1.0; length ratio of midleg = 12.5: 10.5: 3.0: 3.0: 2.0: 1.0: 3.3; length ratio of hindleg = 13.0: 10.0: 3.3: 3.0: 1.7: 1.0: 3.1. Abdomen: Each tergum dark laterally, each abdominal sternum with an inverted U-shaped marking (Figs 23 D, E). Posterolateral spines of abdominal segments VIII and IX relatively small (Figs 24 E, F). Genitalia: Posterior margin of styliger slightly convex. Four segments of forceps uniformly light brown, length ratio of them from basal to apical = 1.5: 2.8: 1.0: 1.0. Inner margin of basal segment of forceps with projection, length of penis longer than styliger (Figs 24 E, F). Dorsal elongation of penis short, blunt, and spineless, dorsal sclerotized transverse band of penis expanded in the middle, inner margin of each penis lobe with approximately 12 small spines, outer margin with approximately 7 serrated small spines. Each penis lobe with a slender and sharp projection posterolaterally and a translucent membranous structure ventrally (Figs 24 G – J). Cerci light brown. Female imago (in alcohol, Fig. 25): Body length 14.0 – 16.0 mm, cerci 13.0 – 15.0 mm, terminal filament 0.1 mm, forewings 8.0 – 10.0 mm, hindwings 4.0 – 5.0 mm. Length ratio of forefemur: foretibia: foretarsal segments I – V = 7.0: 6.8: 2.6: 2.0: 2.0: 1.0: 1.6; length ratio of midleg = 10.8: 8.3: 3.0: 2.3: 1.7: 1.0: 2.3; length ratio of hindleg = 5.5: 3.3: 2.1: 1.6: 1.3: 1.2: 1.0. Color pattern of female similar to male, body dark brown, legs light brown. Wings transparent and veins clearer than in males (Figs 25 A – E). Each tergum dark brown laterally. Each sternum brown with lighter posterior margin. Posterolateral spines of terga VIII and IX invisible (Figs 25 B, C). Sternum VII extended posteriorly into trapezoidal lobe, subanal plate distinctly convex. Abdominal sternum VIII with pair of dark brown, funnel-like sclerotized stripes (Fig. 25 F). Egg: generally oval (Fig. 26 A). Surface nearly smooth (Fig. 26 B).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD0FFDBFF71FF2D7E32FA30.taxon	etymology	Etymology: Due to penis lobe of this species being notably spiny, with approximately 12 small spines near inner margin, it is named ‘ polyspineus ’ here. This specific name combines two words: poly - (multiple) and spineus (spine, small spine).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD0FFDBFF71FF2D7E32FA30.taxon	biology_ecology	Biology: This species is sympatric with S. chankae, S. lacustris, S. palaearcticus, and S. zhelochovtsevi, all collected in the same batch from the Laocaohe in Mohe City, Heilongjiang Province. These species inhabit small, slow-flowing pools near the banks of streams.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD0FFDBFF71FF2D7E32FA30.taxon	distribution	Distribution: China (Heilongjiang Province, Inner Mongolia Autonomous Region).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD0FFDBFF71FF2D7E32FA30.taxon	diagnosis	Diagnosis: S. polyspineus sp. nov. can be distinguished from other species by following characters. Nymph: (1) body relatively smaller than others, from 11.0 to 13.0 mm; (2) wingpads without spots (Figs 20 A, B); (3) Length ratio of first segment of maxillary palp to galea-lacinia about 1.0: 1.0, inner margin of maxillary palp segment II straight (Fig. 21 E); (4) length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 4.0 (Figs 20 C – E); (5) each abdominal sternum with an inverted “ U ” - shaped marking (Fig. 20 B); (6) posterior margin of abdominal sternum IX slightly convex (Figs 20 D, E); (7) dorsal surface and posterior margin of tergum X has sparse stout and pointed spine-like setae, lateral margins lack (Fig. 20 F); (8) outer margins of dorsal and ventral lamellae of both gills I and II concave; costal rib of dorsal lamella in gill II shorter than half of anterior margin (Figs 22 E, F); outer and posterior margins of gill III concave, proximal plate of gill VII poorly developed (Figs 22 G, K).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD0FFDBFF71FF2D7E32FA30.taxon	description	Male imago: (1) smaller body, from 13.0 to 15.0 mm; (2) wings transparent; (3) all legs generally whitish, without distinct marking (Figs 23 A – C); (4) each abdominal sternum with an inverted U-shaped marking (Fig. 23 D); (5) posterolateral spines of abdominal segments VIII and IX relatively small (Figs 24 E, F); inner margin of basal segment of forceps with projection, length of penis longer than styliger (Figs 24 E, F); (6) dorsal elongation of penis short, blunt, and spineless, dorsal sclerotized transverse band of penis expanded in the middle; inner margin with approximately 12 small spines, outer margin with approximately 7 serrated small spines, each penis lobe with a slender and sharp projection posterolaterally (Figs 24 G – J). Female imago: (1) body length 14.0 – 16.0 mm; (2) wings transparent; (3) sternum VII extended posteriorly into a trapezoidal lobe; (4) sternum VIII with a pair of dark brown, funnel-like sclerotized stripes (Fig. 25 F).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD0FFDBFF71FF2D7E32FA30.taxon	discussion	Remarks The association between nymph and imago stages of this new species was confirmed through indoor rearing and COI sequence comparison. The penis lobes of S. lacustris and S. polyspineus sp. nov. are highly similar but exhibit subtle differences. In S. polyspineus sp. nov., dorsal elongation of penis lobe is short and blunt, inner margin of penis lobe has approximately 12 small spines and outer margin has about 7 serrated small spines. The posterolateral projection of penis lobe is slender and sharply pointed (Figs 24 G – J). In contrast, dorsal elongation of penis lobe in S. lacustris is short and sharply pointed, inner margin of penis lobe has 5 – 6 long spines and outer margin has about four small spines. The posterolateral projection of penis lobe is short and broad (Figs 10 H – J). In addition, inner margin of penis lobe in S. polyspineus sp. nov. bears numerous small spines, similar to those of S. abraxas Jacob, 1986 S. columbianus McDunnough, 1925, S. barbaroides McDunnough, 1929, and S. occidentalis Eaton, 1885. However, posterolateral projection of penis lobe of this species is more distinctly slender and sharply pointed, and posterior margin of penis lobe lacks any indentation (Fig. 24 J). Navás (1912) originally described a species Andromina grisea from Far-East Russia. Edmunds (1960) later transferred this species to the genus Siphlonurus, a combination subsequently confirmed by Kluge (2004). This species was based on two female subimaginal specimens. Given the distribution and type locality of Siphlonurus griseus, it is possible that our newly described species, S. polyspineus sp. nov., could be the additional finding of S. griseus. However, this hypothesis requires further verification, including additional collections from the type locality and molecular confirmation via COI sequence analysis. At present, we consider the designation of a new species (S. polyspineus sp. nov.) to be the best arrangement.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD8FFD8FF71F98C7802FA80.taxon	description	Figures 27 – 28	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD8FFD8FF71F98C7802FA80.taxon	materials_examined	Material examined: 10 nymphs, 60 ♀ imagos, 5 ♂ imagos, 1 ♀ subimago, 1 ♂ subimago, Erdao Baihe Town, Fusong County, Jilin Province, 23 – 25. VII. 2008, Shilei Wang and Guo Zhao; 2 ♀ imagos, Hunhe River, Fushun City, Liaoning Province, 41.28444348 ° N, 124.99140257 ° E, ca. 490 m, 29. VII. 2023, Xinhe Qiang; 2 nymphs, 1 ♂ subimago, Laocaohe, Mohe City, Daxinganling District, Heilongjiang Province, 52.833392 ° N, 122.591656 ° E, ca. 480 m, 16 – 19. VII. 2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun; 1 ♀ imago, Dalin River, Mohe City, Daxinganling District, Heilongjiang Province, 52.968586 ° N, 122.269555 ° E, ca. 470 m, 16 – 19. VII. 2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun; 3 ♀ imagos, Genhe, Hexi Street, Genhe City, Hulunbuir City, Inner Mongolia, 50.796106 ° N, 121.578682 ° E, ca. 720 m, 19. VII. 2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun; 15 ♀ imagos, 2 ♂ imagos, Liujiazi, Gaoleng Town, Fangzheng County, Harbin City, Heilongjiang Province, 45.731443 ° N, 129.290088 ° E, ca. 330 m, 21 – 22. VII. 2024, Dewen Gong and Xuhongyi Zheng.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD8FFD8FF71F98C7802FA80.taxon	description	Description: see Kluge (1985).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD8FFD8FF71F98C7802FA80.taxon	distribution	Distribution: China (Jilin Province); Russia, Mongolia.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD8FFD8FF71F98C7802FA80.taxon	diagnosis	Diagnosis Mature nymph: Body length 14.0 – 15.0 mm, wingpads without spots (Figs 27 A, B). Length ratio of first segment of maxillary palp to galea-lacinia about 1.0: 1.0, inner margin of maxillary palp segment II convex apically (Fig. 27 C). Posterolateral spines on terga I – IX gradually larger from anterior to posterior, length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 4.0 (Figs 27 D, E). Each abdominal sternum with inverted U-shaped marking (Fig. 27 B). Posterior margin of abdominal sternum IX slightly convex (Fig. 27 E). Dorsal surface of tergum X with stout spine-like setae, lateral margins lack (Fig. 27 F). Outer margins of dorsal and ventral lamellae of both gills I and II concave, costal rib of dorsal lamella in gill II shorter than half of anterior margin (Figs 27 G, H). Outer and posterior margins of gill III concave, proximal plate of gill VII well developed (Figs 27 I, J).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD8FFD8FF71F98C7802FA80.taxon	description	Male imago: Body length 14.0 – 17.0 mm, wings transparent. Forelegs entirely brown, midlegs and hindlegs entirely light brown (Figs 28 A – C). Each abdominal sternum with inverted U-shaped marking, posterolateral spines of abdominal segments VIII and IX small (Figs 28 D – G). Inner margin of basal segment of forceps with projection, length of penis subequal to styliger (Figs 28 D, E). Dorsal elongation of penis arched and distinctly enlarged apically, outer margin with about 8 small spines, dorsal sclerotized transverse band of penis without expansion, two penis lobes distinctly sclerotized and separated, each tip distinctly bifurcated, ventral side with a translucent membranous projection, inner margin of each penis lobe with 6 – 9 small spines, outer margin concave in the middle (Figs 28 H, I). Female imago: Body length 14.0 – 16.0 mm, wings transparent. Color pattern similar to male (Fig. 28 J). Sternum VII extended posteriorly into a triangular lobe. Sternum VIII dark laterally (Fig. 28 K).	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
E57D87B7FFD8FFD8FF71F98C7802FA80.taxon	discussion	Remarks: S. zhelochovtsevi and S. chankae are very similar, but their male adults can be easily distinguished. In S. zhelochovtsevi, the apical portion of penis lobe elongation is expanded (Figs 28 H, I), whereas in S. chankae, the basal portion is expanded (Figs 2 H – J). However, nymphs of these two species are nearly identical and can only be differentiated by a subtle characteristic: inner margin of second segment of maxillary palp in S. zhelochovtsevi is convex apically (Fig. 27 C), while in S. chankae, it is straight (Fig. 1 C). Species comparison The major morphological differences of nine Chinese Siphlonurus species are listed in the tables 4 – 7.	en	Qiang, Xin-He, Zhou, Chang-Fa (2025): The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae). Zootaxa 5711 (1): 1-56, DOI: 10.11646/zootaxa.5711.1.1, URL: https://doi.org/10.11646/zootaxa.5711.1.1
