taxonID	type	description	language	source
AB7CC720FFD6FFFDFF1DA1D1FB78FE57.taxon	type_taxon	Type species. Chironomus (Leptochironomus) usmaensis Pagast, 1931, by designation of Beck & Beck, 1969: 294. Remarks. Generic diagnoses were given by Cranston et al. (1989) for the adult male, Pinder & Reiss (1986) for the pupa, and Epler et al. (2013) for the larva. The regional keys can be referred to Saether (2010) and Epler (2018), and the worldwide key was proposed by Yan et al. (2005), Pal & Hazra (2018) and Mukherjee et al. (2020).	en	He, Yueran, Tang, Hongqu (2025): Synonymic notes on two Mongolian Cryptotendipes species (Diptera, Chironomidae). Zootaxa 5590 (2): 294-300, DOI: 10.11646/zootaxa.5590.2.10, URL: https://doi.org/10.11646/zootaxa.5590.2.10
AB7CC720FFD6FFFDFF1DA379FAE8F90E.taxon	description	(Figure 1)	en	He, Yueran, Tang, Hongqu (2025): Synonymic notes on two Mongolian Cryptotendipes species (Diptera, Chironomidae). Zootaxa 5590 (2): 294-300, DOI: 10.11646/zootaxa.5590.2.10, URL: https://doi.org/10.11646/zootaxa.5590.2.10
AB7CC720FFD6FFFDFF1DA379FAE8F90E.taxon	materials_examined	Material examined. Holotype of Mongolchironomus mongoljekeus, M (NSMT-I-Dip 5053), labelled “ No. 308: 84 ”. MONGOLIA: Bogd # 9, 44 ° 40 ' N, 102 ° 11 ' E, alt. 1500 m, 13. viii. 1996, leg. H. Suzuki; 1 M, MONGOLIA: Hyargas Nuur, 20. viii. 2019, leg. Q. Han; 4 M, CHINA: Qinghai Province, Lake Qinghai, Daotang stream, 36 ° 34 ' N, 100 ° 44 ' E, alt. 3200 m, 12. vii. 2023, leg. S. Wang; 1 Pe, 3 L, Qinghai Province, Lake Qinghai catchment, a freshwater bog near Gahai, 37 ° 1 ' N, 100 ° 32 ' E, alt., 3210 m, 27. vi. 2016, leg. J. Liu; 1 M (ZSM), RUSSIA: Zabaykalsky Krai, Tshita, Barun-Torei Lake, Cape Myrgen, 20. vi. 1994, leg. V. G. Shilenkov.	en	He, Yueran, Tang, Hongqu (2025): Synonymic notes on two Mongolian Cryptotendipes species (Diptera, Chironomidae). Zootaxa 5590 (2): 294-300, DOI: 10.11646/zootaxa.5590.2.10, URL: https://doi.org/10.11646/zootaxa.5590.2.10
AB7CC720FFD6FFFDFF1DA379FAE8F90E.taxon	discussion	Remarks. The examined holotype (Fig. 1 B) has a relatively slender, spatulate anal point, contrary to the portrayed stout, parallel-sided anal point in the original illustrations (Sasa & Suzuki 1997: 160, figs 11 j, 11 k). The dorsal surface of superior volsella is nearly entirely microtrichiose, and bare on the ventral surface. The ventral tubercles (Fig. 1 C) under T IX are rolled upward. The fused anal tergite band is not well illustrated. A new hypopygium illustration (Fig. 1 C) based on the holotype is shown here, with those of the superior volsella and anal tergite band (Figs 1 F, I) varying in the perceived shape depending on the mounting orientation on the glass slide and pressure from the cover glass. The morphological features of the specimens collected from China, Mongolia and Russia are consist with those of the holotype of Mongolchironomus mongoljekeus Sasa & Suzuki. These specimens undoubtedly belong to the same species. The species is characterised by the color pattern of legs (foreleg entirely dark-brown and mid and hind legs dark-brown only on the tarsi), the scutum with 3 – 4 pairs of acrostichal setae on the middle, the male with the pad-like, microtrichiose superior volsella with a row of several anterior setae. Further, the males of Asian populations examined here have following features: head with weak or no frontal tubercle, total length 3.1 – 4.7 mm, wing length 1.5 – 2.2 mm, AR 2.23 – 2.68, and LR 1 1.35 – 1.48. These fall into the range of variation described by Sublette (1960) and Saether (2010) for Nearctic specimens. The specimen collected from Russia by V. G. Shilenkov, now deposited in Zoologische Staatssammlung, München, Germany (ZSM) satisfies these features (M. Spies, ZSM, Germany, pers. comm.). The BLAST analysis showed that our barcode sequences (DBCCT 012 - 24, DBCCT 013 - 24, DBCCT 014 - 24) have a high similarity (> 98.5 %) with that in the Canadian material identified as Cryptotendipes darbyi (accession numbers KR 633331, KR 618562, KR 642352, KX 281738), of which morphological features are consistent with those of our material, too.	en	He, Yueran, Tang, Hongqu (2025): Synonymic notes on two Mongolian Cryptotendipes species (Diptera, Chironomidae). Zootaxa 5590 (2): 294-300, DOI: 10.11646/zootaxa.5590.2.10, URL: https://doi.org/10.11646/zootaxa.5590.2.10
AB7CC720FFD6FFFDFF1DA379FAE8F90E.taxon	distribution	Distribution. The species has a Holarctic distribution, from North America (USA and Canada) to Europe (Central Finland), and further to the Mongolian Plateau and the Tibetan Plateau in Asia. The distribution is shown in Fig. 3.	en	He, Yueran, Tang, Hongqu (2025): Synonymic notes on two Mongolian Cryptotendipes species (Diptera, Chironomidae). Zootaxa 5590 (2): 294-300, DOI: 10.11646/zootaxa.5590.2.10, URL: https://doi.org/10.11646/zootaxa.5590.2.10
AB7CC720FFD3FFF8FF1DA1FDFF65FBD8.taxon	description	(Figure 2)	en	He, Yueran, Tang, Hongqu (2025): Synonymic notes on two Mongolian Cryptotendipes species (Diptera, Chironomidae). Zootaxa 5590 (2): 294-300, DOI: 10.11646/zootaxa.5590.2.10, URL: https://doi.org/10.11646/zootaxa.5590.2.10
AB7CC720FFD3FFF8FF1DA1FDFF65FBD8.taxon	materials_examined	Material examined. Holotype of Mongolchironomus mongolkeleus, M (NSMT-I-Dip 5054), labelled “ No. 308: 86 ”, MONGOLIA: Bogd # 9, 44 ° 40 ' N, 102 ° 11 ' E, alt. 1500 m, 13. viii. 1996, leg. H. Suzuki; 1 M, 1 F, CHINA: Qinghai Province, Lake Qinghai, River Heima, 36 ° 41 ' N, 99 ° 53 ' E, alt. 3260 m, 22. vii. 2023, leg. H. Tang; 2 L, as previous except 36 ° 42 ' N, 99 ° 45 ' E, alt. 3290 m, leg. X. Qiu, 23. vi. 2016; 3 M, 2 Pe, Xinjiang Province, Ruoqiang County, Lop village, Lake Tetma, 39 ° 29 ' N, 88 ° 17 ' E, alt. 808 m, 20. viii. 2024, leg. Z. Wu; 2 L, as previous except 21. viii. 2015, leg. Y. Zhang; 1 M, MONGOLIA: Uvs Aimag, Tes Sum, Uvs Nuur, 22. viii. 2019, leg. Q. Han.	en	He, Yueran, Tang, Hongqu (2025): Synonymic notes on two Mongolian Cryptotendipes species (Diptera, Chironomidae). Zootaxa 5590 (2): 294-300, DOI: 10.11646/zootaxa.5590.2.10, URL: https://doi.org/10.11646/zootaxa.5590.2.10
AB7CC720FFD3FFF8FF1DA1FDFF65FBD8.taxon	discussion	Remarks. The re-examination of the holotype of Mongolchironomus mongolkeleus Sasa & Suzuki revealed that in the original description, the authors (1997: 160, fig. 12 g) overlooked the heavily pigmented median longitudinal ridge (band) on the anal tergite (Fig. 2 B). In addition, they illustrated the dorsal appendage as if it has a large bare base. Actually, the strange base is an interface forming a boundary between the volsella and the gonocoxite. The interface (Figs 2 G, H) is easily distorted by pressure on the coverslip. Thus, the features of specimens newly collected from China are consistent with those of the holotype of M. mongolkeleus. Further, the collection information on the holotype of M. mongolkeleus contradicts the published data (Sasa & Suzuki 1997: 161). The label reads “ Ulaanbaatur # 20, 9. viii. 1996 ”, whereas the publication lists “ Bogd # 9, 13. viii. 1996 ”. We adopt the published data, as the original label is possible to have been revised once. Adult males collected from China have the following features: total body length 4.1 – 5.8 mm, wing length 1.9 – 2.5 mm, AR 2.45 – 3.00 and LR 1 1.37 – 1.52. These measurement data and ratios satisfy the original description of Cryptotendipes acalcar Reiss, 1990. Mongolchironomus mongolkeleus is a junior synonym of Cryptotendipes acalcar Reiss. Two barcodes for C. acalcar (DBCCT 009 - 24, DBCCT 010 - 24) are newly provided here based on Chinese specimens.	en	He, Yueran, Tang, Hongqu (2025): Synonymic notes on two Mongolian Cryptotendipes species (Diptera, Chironomidae). Zootaxa 5590 (2): 294-300, DOI: 10.11646/zootaxa.5590.2.10, URL: https://doi.org/10.11646/zootaxa.5590.2.10
AB7CC720FFD3FFF8FF1DA1FDFF65FBD8.taxon	distribution	Distribution. The species is previously only known from Turkey and Mongolia, and is now shown to occur in the northwest of China, the Lake Qinghai catchment and the southeast of Xinjiang Prefecture. The distribution is shown in Fig. 3.	en	He, Yueran, Tang, Hongqu (2025): Synonymic notes on two Mongolian Cryptotendipes species (Diptera, Chironomidae). Zootaxa 5590 (2): 294-300, DOI: 10.11646/zootaxa.5590.2.10, URL: https://doi.org/10.11646/zootaxa.5590.2.10
