Hedwigia stellata Hedenäs, J. Bryol.

Huang, Wen-Zhuan, Ma, Wen-Zhang, Ignatov, Michael S., Ignatova, Elena A., Sulayman, Mamtimin, Wu, Yu-Huan & Zhu, Rui-Liang, 2024, A taxonomic revision of Hedwigia (Hedwigiaceae, Hedwigiales) in China, Phytotaxa 634 (3), pp. 215-234 : 231

Hedwigia stellata Hedenäs, J. Bryol. 18(1): 144. 1994.

Type: — SWEDEN. Skåne, Ö. Broby, Sanatoriet, 5 Aug. 1918, Hj. Moller s.n. (holotype: S).

Note:— Hedwigia stellata is characterized by (1) the presence of a single, branched papilla per cell on abaxial side of median laminal cells, (2) reflexed leaf apices when dry, and (3) smooth median laminal cells that are not porose ( Hedenäs 1994; Ignatova et al. 2016).

For Hedwigia stellata, Dalton et al. (2013) cited seven specimens from Sichuan and one from Yunnan. We sequenced two specimens from Sichuan and three specimens from Yunnan with branched papillae (which is the main diagnostic character of H. stellata in this region, according to Dalton et al.) and all of them were resolved in the molecular phylogenetic tree very far from H. stellata . We think this selection is comprehensive, considering also the similar result in Asian Russia. Ignatov et al. (2000) also found Hedwigia with branched papillae in Asian Russia and published this result. However subsequent molecular studies showed that Siberian “ H. stellata ” does not fit European one by DNA sequences, and also differs in some morphological characters. Morphological distinctions of European H. stellata s.str. such as conspicuously bent leaf tips are not included in Dalton et al (2013) ’s circumscription of the Sino- Himalayan material. Also, spores described by Dalton et al. (2013) are 22−25 μm, whereas in European H. stellata 23−29.5 μm and in Chinese H. sinica (which was likely named as H. stellata by Dalton et al. (2013), spores are 20−26 μm. In addition, our investigation in Sichuan, Yunnan and Xizang also did not yield any evidence of the presence of H. stellata , and all specimens with a single papilla per cell in mid-leaf which were examined from southwestern China are attributed to H. sinica .

Key to Chinese species of Hedwigia (Note: The records of H. stellata and H. ciliata in China are doubtful).

1. Mid-leaf cells with 1(–2) strongly branched, stellate abaxial papillae...............................................................................................2

1. Mid-leaf cells with 2 or more simple or slightly branched abaxial papillae ......................................................................................4

2. Leaf apices reflexed when dry; median laminal cells slightly incrassate, not porose...........................................[ Hedwigia stellata ]

2. Leaf apices straight when dry; median laminal cells strongly incrassate and porose ........................................................................3

3. Capsules obovate to obconic, broadest just below mouths; calyptrae with sparse hairs at the base; leaves with length/width ratio (2.5−)2.9−3.3(−3.9) .................................................................................................................................................... Hedwigia sinica

3. Capsule ovate to obovate, with the broadest part shortly above the middle; calyptrae strongly hairy almost throughout; leaves with length/width ratio (1.7−)2.1−2.6(−3.0) ........................................................................................................ Hedwigia czernyadjevae

4. Hyaline leaf apices short, constituting (3−)5−8(−18) % of leaf length, usually less than 10 % .......................... Hedwigia filiformis

4. Hyaline hair-points short to very long, constituting (15−)20−55% of leaf length .............................................................................5

5. Leaf margins narrowly recurved in proximal 2/3–3/4; spores 28−35(−38) μm; hyaline hair-points constituting 15–25% of leaf length ...................................................................................................................................................................... [ Hedwigia ciliata ]

5. Leaf margins narrowly recurved in proximal 1/5–1/2; spores 20−25(−28) μm; hyaline hair-points constituting (20–)30–55% of leaf length ...................................................................................................................................................................... Hedwigia emodica