The genus Aleuritopteris Fee (Cheilanthoideae, Pteridaceae) comprises approximately 100 species distributed across tropical and subtropical regions worldwide (Schuettpelz et al., 2025). However, extensive morphological convergence, pronounced phenotypic plasticity, and overlapping character states make species identification and taxonomic delimitation within the genus highly challenging. Historically, Wu (1981) provided the first comprehensive taxonomic treatment of Aleuritopteris in China, which includes A. shensiensis. Although A. shensiensis Ching was later reduced to the variety A. argentea var. obscura (Christ) Ching (Zhang and Yang, 2011), Kalyuzhny and Chimitov (2013) subsequently extended the known range of A. shensiensis to Irkutsk, Russia, with further morphological notes (Chimitov et al., 2026).

To date, the documented flora of Mongolia includes 8 species of lycophytes across 4 genera and 2 families, and 41 species of ferns across 17 genera and 12 families (Grubov, 1982; Gubanov, 1996; Urgamal et al., 2014; Chuluunbat et al., 2024; Baasanmunkh et al., 2026). Within the genus Aleuritopteris, only the species A. argentea has been reported previously in Mongolia. Before this study, A. shensiensis was never recorded in Mongolia. Previously, A. shensiensis was known only from Buryatia, Irkutsk region, Rusia, and several provinces across China, including Gansu, Guizhou, Hebei, Henan, Liaoning, Qinghai, Shandong, Shaanxi, Shanxi, Sichuan, and Yunnan (Zhang et al., 2013; Chimitov et al., 2026).

Here, based on field surveys, we report A. shensiensis as a new record for Mongolia. To facilitate its recognition, we provide a detailed morphological description, distribution map, photographs, and an identification key.

The field surveys were conducted in the Mongolian Dauria and Middle Khalkh phytogeographical regions of Mongolia in 2021 and 2025. Detailed photographs were taken during the field surveys. Herbarium specimens were deposited in the Institute of General and Experimental Biology, Siberian Branch of the Russian Academy of Sciences (UUH). For species identification and specimen examinations, we consulted herbarium collections from UBA, UBE, MW, NS, and NSK, as well as online databases including the Global Biodiversity Information Facility (GBIF, 2026; https://www.gbif.org/) and iNaturalist (iNaturalist, 2026). The distribution map of Mongolia was compiled based on field observations, herbarium specimens, and collection locations and was created using ArcGIS 10.4.1 software.

Aleuritopteris shensiensis Ching, Fl. Tsinling. 2: 66, 1974. — TYPE: CHINA. Shaanxi province: Ning-Shen (Ningshan County), H.W. Kung 3110 (holotype: PE 00049594!; isotype [2 sheets]: PE 00539533!, PE 00539531!).

Cheilanthes argentea var. obscura Christ, Nuovo Giorn. Bot. Ital. n. s. 4: 88, 1897; Aleuritopteris argentea var. obscura (Christ) Ching, Hong Kong Naturalist 10: 198.

Aleuritopteris shensiensis differs from A. argentea according to its glabrous abaxial frond surface, which lacks white or pale-yellow farina (Fig. 1). The morphological characteristics of the Mongolian specimens are fully consistent with those previously reported from China and Russia, and the absence of farina on the abaxial frond surface reliably distinguishes A. shensiensis from the co-occurring A. argentea, confirming the identification of the Mongolian material.

Rhizomes erect or ascending; scales bicolorous, bright chestnut-colored, lanceolate. Fronds clustered. Stipe chestnut-colored to black, lustrous, 3–20 cm, scaly at base. Lamina pentagonal or ovate-pentagonal, finely dissected, glabrous, lacking farina abaxially, 2–11 × 2–9 cm, 3-pinnatifid, papery when dry, adaxially glabrous; rachis of same color as stipe, costae of lighter color than the stipe. Pinnae 3–5 pairs, opposite; basal pair largest, 2.5–5 × 2–4 cm, right-triangular; pinnules 3 or 4 pairs, proximal basiscopic pinnule largest, 2–3 cm × 4–9 mm, oblong-lanceolate, pinnatifid to 2 pairs or simple; other pairs gradually shortened distally, lanceolate, simple; ultimate segments deltoid or falcate. Veins pinnate, obscure. Sori consisting of 3 to several sporangia, confluent at maturity. False indusia continuous, yellowish green, membranous, margins entire. Perispore granular.

Habitat: Rock crevices, cracks in the rocks

Phenology: Spores maturing in July to September

Geographical distribution: China (Gansu, Guizhou, Hebei, Henan, Liaoning, Qinghai, Shandong, Shaanxi, Shanxi, Sichuan, Yunnan); Mongolia (Mongolian Dauria, Middle Khalkh); Russia (Buryatia, Irkutsk region, Rusian Far East)

Specimens examined: MONGOLIA. Middle Khalkh: Bulgan province, Gurvanbulag soum, Khogno Khan National Park, Khogno Khan mountain, 20 Sep 2025, 47°25′40.8″N, 103°39′19.1″E, 1,354 m a.s.l., Daba G. Chimitov 024700 (UUH). Mongolian Dauria region: Khentii province, Dadal soum, Ereendavaa, Onon river, 12 Aug 1990, 49°2′2.95″N, 111°51′17.60″E, 900 m a.s.l., R.V. Kamelin, I.A. Gubanov, Sh. Dariimaa 764 (MW0168218) (Fig. 2).

Additional specimens of Aleuritopteris argentea examined: MONGOLIA. Khuvsgul region: Bulgan province, Teshig soum, Khorgol lake, 24 Aug 1985, 49°58′14″N, 102°44′45″E, 1,246 m a.s.l., E. Ganbold 2237 (UBA0002439). Khuvsgul province, Khankh soum, Khuvsgul lake, Turt, 27 Jun 1971, 51°30′N, 100°42′E, 1,671 m a.s.l., L.I. Malishev (NSK0070191). Selenge province, Tushig soum, Zelter river, 22 Jun 2012, 50°17′N, 104°55′E, 768 m a.s.l., D.N. Shaulo 44 (NS0010705). Khangai region: Arkhangai province, Bulgan soum, Khoid-Tamir river, 17 Aug 1926, 47°6′N, 101°27′E, 1,000 m a.s.l., N.V. Pavlov 4 (NS0008836). Arkhangai province, Ikh-Tamir soum, Tamir river, 29 Jul 1924, 47°26′27.29″N, 101°30′45.92″E, 1,900 m a.s.l., N.V. Pavlov 147 (MW0168229). Selenge province, Baruunburen soum, Bulgan and Onon river, 20 Aug 1985, 49°30′N, 105°5′E, 1,300 m a.s.l., I.A. Gubanov 9722 (MW0168220). Khuvsgul province, Alag-erdene soum, Eg river, 14 Jul 1975, 50°24′N, 100°10′1.20″E, 1,645 m a.s.l., A.A. Chepurnov (NS0070190). Arkhangai province, Tuvshruuleh soum, 15 km south of the soum center, 23 Jun 1979, 47°14′36.05″N, 101°58′3.16″E, 1,900 m a.s.l., I.A. Gubanov 315 (MW0168226). Arkhangai province, Tuvshruuleh soum, 25 km south of the soum center, 29 Jun 1979, 47°8′51.72″N, 102°0′10.47″E, 1,900 m a.s.l., I.A. Gubanov 413 (MW0168224). Mongolian Dauria region: Khentii province, Norovlin soum, Ereendavaa, Onon river, 2 Aug 1987, 48°52′N, 111°45′E, 900–1,350m a.s.l., R.V. Kamelin, A.L. Budantsev 2414 (MW0168215). Tuv province, Zaamar soum, Ulaanbaatar-Bulgan road, 17 km east of the bridge across Tuul river, 22 Jul 1982, 48°14′27.68″N, 104°32′10.61″E, 1,244 m a.s.l., I.A. Gubanov 5273 (MW0168223). Selenge province, Orkhon soum, Orkhon river, 23 Aug 1980, 49°7′4.49″N, 105°20′38.10″E, 720 m a.s.l., I.A. Gubanov 3866 (MW0168219). Mongolian Altai region: Khovd province, Buyant river valley, 25 Aug 1983, 47°53′39.08″N, 91°13′51.54″E, 1,800 m a.s.l., I.A. Gubanov 6734 (MW0168222). Gobi Altai region: Bayankhongor province, Bogd soum, Ikh Bogd mountain, 22 Jul 2019, 45°0′59.83″N, 100°22′52.64″E, 1,850 m a.s.l., D. Lyskov, P. Karpunina, V. Rusanova, S. Boldyrev 27-MN-19 (MW0195346). Transaltai Gobi region: Bayankhongor province, Shine-Jinst soum, Jinst mountain, 27 Jul 1978, 43°57′42.07″N, 99°13′17.94″E, 1,275 m a.s.l., G.N. Ogureeva (MW0168227) (Fig. 2).

The occurrence of A. shensiensis in Mongolia is biogeographically significant for several reasons. First, Mongolia lies within a transitional zone between the Central Asian and East Asian floristic regions, and the presence of this species suggests that the montane rocky habitats of north-central Mongolia serve as stepping-stone habitats linking populations in Siberia and China. Second, the species’ preference for rock crevices and rocky outcrops, microhabitats that provide relatively stable moisture and temperature conditions, likely facilitates its persistence within Mongolia’s predominantly arid environment. Similar disjunct distribution patterns have been documented for other pteridophytes in Mongolia, including Selaginella sibirica (Milde) Hieron. (Chuluunbat et al., 2024), suggesting that such previously overlooked occurrences and range extensions may be more widespread than currently recognized.