Four Remarkable Additions to the Biodiversity of Chinese Mosses

Four species of moss genus Schistidium are reported for the first time from China. All of them have been found in the Xinjiang Uyghur Autonomous Region. Ecological and distributional details of the newly recorded species are provided and their local distribution is mapped. Photographs of the species are attached. Checklist of Schistidium species and identifying key are added. Considering the present records, Schistidium consists of 15 species in China.


Introduction
The genus Schistidium (Grimmiaceae, Bryophyta) represents an example of outstanding diversity, which was neglected until thorough morphological revision of S. apocarpum group by Blom [1]. This revision resurrected from oblivion a number of already existing names and 13 species were described as new for science. Moreover, this revision created a frame, which allowed further increase in the formally recognized biodiversity within the genus by means of regional alpha-taxonomic studies. In the course of such studies, a number of Schistidium species were described from Europe [2,3], North America [4][5][6] Russia [7,8] and China [9][10][11], as well as from North Africa [12] and South America [13]. Molecular data [7,14] supported the narrow species concepts of suggested by Blom [1].
Cao and Vitt [15] revised genera Schistidium and Grimmia and recognized six species of Schistidium there (including Schistidium apocarpum (Hedw.) Bruch & Schimp., S. liliputanum (Müll. Hal.) Deguchi, S. rivulare (Brid.) Podp., S. strictum (Turner) Loeske ex Mårtensson, S. subconfertum (Broth.) Deguchi, and S. trichodon (Brid.) Poelt), as well as supported Schistidium as an independent genus in Grimmiaceae. Cao et al. [16] transferred Grimmia chenii S.H. Lin, known from Xizang and Xinjiang Provinces, into the genus Schistidium as S. chenii (S.H. Lin) T. Cao, C. Gao & J.C. Zhao. One next species S. sinensiapocarpum (Müll. Hal.) Ochyra, described from China (Shaanxi Province) already in 1898 by Carl Müller [17], was considered as a synonym of S. strictum by Cao et al. [18] and was not listed by them as separate species in the Moss flora of China. However, these two species are again distinguished now [19]. On the other hand, both Blom [1] and Ignatov [19] agree that S. strictum, formerly considered widespread throughout the Northern Hemisphere, occurs only in territory of Great Britain, Iceland, western Scandinavia, on the west coast of North America and very rarely also in the Pyrenees and Madeira. The occurrence of the species in China is therefore very unlikely and it is necessary to remove it from the Chinese checklist.
Recently, Blom et al. [9] [20] that increased the number of Chinese Schistidium species to eleven. The data presented above together with four newly reported taxa confirm the presence of fifteen Schistidium species in China.

Ecological and Phytogeographic Characteristics
Xinjiang Uyghur Autonomous Region occupying about 1/6 of the national territory, is the largest province of China [21]. It is located in the northwestern boundary of China with a total land area of 1,657,549 km 2 . From north to south there are three mountain ranges across Xinjiang, namely, Altai, Tianshan and Kunlun, with the geomorphologic features being characterized by two basins called the Junggar Basin and the Tarim Basin among three mountains. Therefore, the geographical and geomorphologic features are very complex and diverse in Xinjiang Province [21].
Xinjiang Province is situated in the hinterland of the Asia-Europe continents and is far away from the oceans. In addition, the Himalaya Range blocks the warm moist air currents from the Indian Ocean to arrive in Xinjiang, which is called the "blocking effect" [22]. Just as the causes above, the precipitation is very low and the plant distribution is also uneven (mostly concentrated in the mountains), resulting in the formation of a typical arid and semi-arid climate. Hydrologically, in general, there is a progressive increase in precipitation from south to north, in detail, the average annual precipitation of the basin is about 10-100 mm, that of the mountain is 250-530 mm, while the annual evaporation of the southern border is 1000-1550 mm, that of the north for 1000-1200 mm.
Bryophytes are mainly distributed in the three mountain ranges, so it is necessary to describe the three mountains' geography, hydrology and vegetation [21,22]. Because of the special environment and topography, Xinjiang has a unique flora representing a mixture of circum-boreal, Irano-Turanian and Eastern Asiatic taxa [21,22]. The vegetation of Altai and Tianshan has apparent vertical distribution belts caused by climate and topography, including desert, steppe zone, mixed conifer, coniferous forest, sub-alpine meadow belt, alpine meadow and alpine vegetation zones. Compared with those of Altai and Tianshan, the Kunlun Mountains lack forest zones, and the distribution belts of the desert and steppe of mountains are rather broad [23,24].

Materials
Totally, 651 specimens of Schistidium species were collected by Mamtimin Sulayman and his research team in Xinjiang province during the last 30 years. They mainly explored mountain ranges of the western part of China, particularly Altai Mts, Tianshan Mts, Kunlun Mts and Pamir plateau.
All materials are located in the herbarium of Xinjiang University, China (XJU) and partially also in the herbarium of the University of Ostrava, Czech Republic (OSTR).
The revision of all these collected materials made by authors during 2020-2022 showed that four of the Schistidium species were found for the first time in China.
For the identification of the collected material, mainly Moss flora of China, Volume 3 [18] and Moss flora of Russia, Volume 2 [19] were used.
Detailed photo documentation was taken for each of the presented species. The pictures show only material from the herbarium specimens listed below-see captions near each image for details. The extent of quality of the photographs reflects sometimes the condition of the collected material, which was sometimes slightly damaged-but not so much that it could not be reliably identified.

New Species for China
During bryological expeditions carried out in Xinjiang province during the last 30 years, an extensive collection of Schistidium specimens was collected by M. Sulayman and his research team. Four of the species, Schistidium flaccidum, S. marginale, S. pulchrum, and S. sibiricum have not hitherto been recorded in China.
condition of the collected material, which was sometimes slightly damaged-but not so much that it could not be reliably identified.

New Species for China
During bryological expeditions carried out in Xinjiang province during the last 30 years, an extensive collection of Schistidium specimens was collected by M. Sulayman and his research team. Four of the species, Schistidium flaccidum, S. marginale, S. pulchrum, and S. sibiricum have not hitherto been recorded in China.
Schistidium flaccidum (De Not.) Ochyra- Figure 1, and map: Figure 5 (spot 1). Schistidium flaccidum is characterized by long and broad-based awns, light-colored capsules with red rims, a rudimentary peristome, and a short mamillate rostrum. Description: plants olivaceous or light brown, from 0.5 cm till 2 cm high; leaves erect or weakly curved when dry, ovate-lanceolate, strongly keeled; capsule orange-brown, cupulate, from 0.6 mm till 1 mm long. Capsules are produced from late spring to early summer. This species is characterized by small plant size, perichaetial leaves remarkably larger than lower leaves, plicate, rather weak, not decurrent hyaline hair point, short, cupulate capsule with strongly reduced peristome and flat operculum with only short rostrum.
Ecology: mainly on rocks in open to shaded habitats; occasionally also on an anthropogenic substrate [19]. Schistidium flaccidum is characterized by long and broad-based awns, light-colored capsules with red rims, a rudimentary peristome, and a short mamillate rostrum.
Description: plants olivaceous or light brown, from 0.5 cm till 2 cm high; leaves erect or weakly curved when dry, ovate-lanceolate, strongly keeled; capsule orange-brown, cupulate, from 0.6 mm till 1 mm long. Capsules are produced from late spring to early summer. This species is characterized by small plant size, perichaetial leaves remarkably larger than lower leaves, plicate, rather weak, not decurrent hyaline hair point, short, cupulate capsule with strongly reduced peristome and flat operculum with only short rostrum.
Ecology: mainly on rocks in open to shaded habitats; occasionally also on an anthropogenic substrate [19]. Schistidium flaccidum is a generitype of the genus Schistidium. It has disjunctive distribution, largely associated with Europe, where it reaches Caucasus Eastwards and Western North America with few scattered localities in North Africa and GBIF database [19,25]. Until the present, this species has been known in Asia from a single locality in Transcaucasia two collections in Russian Altai and one recent collection from Tyva Republic, Russia [19,26]. In Siberian localities, it grows on dry rocks in the subalpine to lower alpine belts at elevations 2200-2450 m.
Schistidium marginale H.H. Blom, Bednarek-Ochyra & Ochyra- Figure 2, and map: Figure 5 (spot 2). Schistidium flaccidum is a generitype of the genus Schistidium. It has disjunctive distribution, largely associated with Europe, where it reaches Caucasus Eastwards and Western North America with few scattered localities in North Africa and GBIF database [19,25]. Until the present, this species has been known in Asia from a single locality in Transcaucasia two collections in Russian Altai and one recent collection from Tyva Republic, Russia [19,26]. In Siberian localities, it grows on dry rocks in the subalpine to lower alpine belts at elevations 2200-2450 m.
Schistidium marginale H.H. Blom, Bednarek-Ochyra & Ochyra- Figure 2, and map: Figure 5 (spot 2).  Schistidium marginale has Eurasian distribution from central Europe, where it was described in Russian Far East. In Asia, it is known to occur in Georgia, Turkey and throughout the Asian part of Russia. Within the latter, the species is rather frequent in Transbaikalia, scattered localities with few scattered localities in Putorana Plateau, Eastern part of Yakutia, Altai, Kuznetsky Alatau and Tukuringra mountains [19,26]. In the south Siberian mountains it typically occurs in the forest belt, occupying an altitudinal range of 600-1700 m, on shaded siliceous rocks [19,26].
Description: plants small, dull or brownish above, from 1 to 2.5 cm high, leaves densely set, shiny, erect, narrowly ovate-triangular, keeled; Sporophytes greyish-brown, shiny, obloid-cylindrical, becoming finely striate with age, from 0.6 mm to 1 mm long. This species is characterized by small plant size, keeled distal portions of leaves with short and strongly denticulate hyaline own, costae irregularly angulate on the cross-section and strongly incrassate 2-4 layered distal leaf margins [19].
Ecology: grows mainly on inclined rock ledges [19].  Schistidium marginale has Eurasian distribution from central Europe, where it was described in Russian Far East. In Asia, it is known to occur in Georgia, Turkey and throughout the Asian part of Russia. Within the latter, the species is rather frequent in Transbaikalia, scattered localities with few scattered localities in Putorana Plateau, Eastern part of Yakutia, Altai, Kuznetsky Alatau and Tukuringra mountains [19,26]. In the south Siberian mountains it typically occurs in the forest belt, occupying an altitudinal range of 600-1700 m, on shaded siliceous rocks [19,26].
Description: plants small, dull or brownish above, from 1 to 2.5 cm high, leaves densely set, shiny, erect, narrowly ovate-triangular, keeled; Sporophytes greyish-brown, shiny, obloid-cylindrical, becoming finely striate with age, from 0.6 mm to 1 mm long. This species is characterized by small plant size, keeled distal portions of leaves with short and strongly denticulate hyaline own, costae irregularly angulate on the cross-section and strongly incrassate 2-4 layered distal leaf margins [19].
Morphologically S. pulchrum resembles S. apocarpum (Hedw.) Bruch & Schimp., but differs in having smaller plants with shorter leaves, which are straight rather than curved, and subentire upper leaf margins. For details of the species morphology see [19,25].
Schistidium pulchrum is a widespread circumpolar montane species throughout the northern Holarctic. It occurs in most Arctic archipelagoes, well studied for bryophytes throughout the Arctic and boreal zones, declining southward within the temperate zone. Description: plants olivaceous, sometimes brownish, from 1.5 to 5 cm high; leaves erect, ovate-lanceolate, sharply keeled distally; capsule orange-brown, cylindric, from 0.8 to 1.3 mm, produced late spring to early summer.
Morphologically S. pulchrum resembles S. apocarpum (Hedw.) Bruch & Schimp., but differs in having smaller plants with shorter leaves, which are straight rather than curved, and subentire upper leaf margins. For details of the species morphology see [19,25].
Ecology: mainly on rocks in somewhat shaded habitats [19]. Specimen examined. W border of Xinjiang Uyghur Autonomous Region. 500 km SW of Urumqi; Tuo mu er peak National Reserve, Tuo mu er peak, ca. 2400 m a.s.l.   With its lacking hyaline hair point and costae short excurrent as a yellowish mucro, Schistidium sibiricum is quite distinct morphologically and may hardly be confused with the other Schistidium species except subatlantic S. canadense and Beringian S. frahmianum. This trait distinguishes it from S. apocarpum, which resembles S. sibiricum in general aspect, leaf shape, serrulate in upper leaf portion, peristome teeth strongly perforated, curved to twisted when dry [7]. Schistidium canadense, which for some time was considered a subspecies of S. apocarpum resembles S. sibiricum, even stronger, since it often has chlorophyllous leaf awns, and some older specimens of S. sibiricum were referred to S. canadense/S. apocarpum ssp. Canadense. However, molecular data showed that these species are not close phylogenetically and their resemblance has originated from convergent evolution [7,19]. Schistidium sibiricum has mainly Asian distribution with few localities in the Ural Mountains, Kola Peninsula, south Finland and northern Norway. In Asia, it is a frequent species in the mountains of south Siberia and the southern part of the Russian Far East with several records from Kamchatka [7,19,26]. With its lacking hyaline hair point and costae short excurrent as a yellowish mucro, Schistidium sibiricum is quite distinct morphologically and may hardly be confused with the other Schistidium species except subatlantic S. canadense and Beringian S. frahmianum. This trait distinguishes it from S. apocarpum, which resembles S. sibiricum in general aspect, leaf shape, serrulate in upper leaf portion, peristome teeth strongly perforated, curved to twisted when dry [7]. Schistidium canadense, which for some time was considered a subspecies of S. apocarpum resembles S. sibiricum, even stronger, since it often has chlorophyllous leaf awns, and some older specimens of S. sibiricum were referred to S. canadense/S. apocarpum ssp. Canadense. However, molecular data showed that these species are not close phylogenetically and their resemblance has originated from convergent evolution [7,19]. Schistidium sibiricum has mainly Asian distribution with few localities in the Ural Mountains, Kola Peninsula, south Finland and northern Norway. In Asia, it is a frequent species in the mountains of south Siberia and the southern part of the Russian Far East with several records from Kamchatka [7,19,26].

Checklist of Schistidium Species in China
At present, an occurrence of 15 species of the genus Schistidium is provably known in China. Four of them (marked in bold below) are newly recorded species. On the contrary, S. striatum, has been removed from the list due to the very unlikely occurrence in Chinese territory.
Accepted Taxa (newly recorded taxa

Checklist of Schistidium Species in China
At present, an occurrence of 15 species of the genus Schistidium is provably known in China. Four of them (marked in bold below) are newly recorded species. On the contrary, S. striatum, has been removed from the list due to the very unlikely occurrence in Chinese territory.
Accepted Taxa  Note: The distribution of S. strictum in China is highly unlikely given that the area of occurrence of the species is quite far from the Chinese territory [1,19]. Previously this species was considered in a broader sense, including most of the currently recognized species of the genus with papillose leaf lamina, while S. strictum s.str. has suboceanic distribution in Europe and along the western coast of North America [25]. Special revision of the specimen is needed to assign it to one of the narrower circumscribed species; in Russia, S. papillosum Culm. is the most common species with papillose cells of leaf lamina, and most records of S. strictum were later referred to it. Southwards, it reaches the mountains of south Siberia and could occur in China as well. 11a. Leaf margin in upper part distally denticulate 12 11b. Leaf margin smooth along the entire length