Phaeoceros himalayensis Bapna & G. G. Vyas

Phaeoceros himalayensis (Kashyap) Prosk. ex Bapna & G. G. Vyas, J. Hattori Bot. Lab. 25: 88. 1962. Figs 4, 5, 10 E, F ≡ Anthoceros himalayensis Kashyap, New Phytol. 14 (1): 8. 1915. Type. India • Western Himalayas: Mussoorie, Kashyap’s illustration (lectotype: Illustration in New Phytologist 14: 8. fig. 4.4. 1915; designated by Chantanaorrapint et al. (2015)). Description. Thallus bright green in fresh specimens, becoming yellowish green to brown when dry, growing prostrate, moderately adhering to substrate, forming irregular patches or sometimes fan-shaped colonies, irregularly branched into several lobes, thallus lobe lingulate to obovate, fan-shaped, or tapering toward apex, 4–12 mm long, 1–5 mm wide; margins nearly entire to irregularly crenulate, flat, rarely ascending upward; apex round to lobulate, frequently attenuated into tuber, rarely curving upward; tubers frequently present, occurring at apex, along margin, or on ventral surface of thallus, with a stalk to 5 mm long, ovoid to subspherical. Thallus in cross section plano-convex to concave-concave, 5–8 cells thick in the middle region. Dorsal epidermal cells irregular hexagonal to heptagonal, 42–100 × 25–48 µm. Chloroplasts 1 per cell, expanded, occupying nearly entire to about half of cell size, frequently contracted into round shape, pyrenoid smooth. Nostoc colonies scattered through the ventral side of thallus, appearing as dark dots. Rhizoids sparse, scattered on ventral surface, smooth in early stage, becomes pegged at maturity, hyaline to pale brown. Sexuality monoicous, weakly protandrous. Androecia sparse, slightly raised over the dorsal surface of thallus, (1 –) 2–4 antheridia per chamber. Archegonia embedded in thallus, connected to the upper surface, sparse, randomly scattered nearly thallus apex. Involucres erect, cylindrical, 1.1–2 mm long, mouth smooth to shallowly crenulate. Sporophytes frequent, capsules erect, cylindrical, up to 12 mm long at maturity; epidermal cells of capsule elongate-rectangular, 82–245 × 12–28 µm, thick-walled; stomata 57–83 × 40–53 µm, surrounded by 5–6 epidermal cells; assimilative layer 3–5 cells thick in cross section; the innermost cells of capsule elongate rectangular to hexagonal, 37–125 × 7–30 µm, pale brown to dark brown; columella consisting of 5–10 cells in cross section, brown to dark brown. Spores yellowish brown to dark brown, 27–35 µm in equatorial diameter; distal face with irregular verrucose projections, sometimes with aggregation in center; proximal face with distinct thin triradiate mark, finely vermiculate along its length; each facet finely vermiculate, with a central depression occasionally with sparsely surrounded by papillae. Pseudoelaters pale to dark brown at maturity, thin to thick-walled, occasionally branched, 1–3 cells long; pseudoelaters cells rectangular, without helicoidal band. Distribution, habitat, and ecology. Phaeoceros himalayensis is currently known from India (Asthana and Srivastava 1991) and Thailand (Chantanaorrapint et al. 2015). It occurs on rocks and soil in open sites in grassland, pine-oak mixed montane deciduous, and subalpine forests at elevations between 1,000 and 2,200 m. It may grow associated with other bryophytes such as Asterella khasyana (Griff.) Pandé et al., Cyathodium aureonitens (Griff.) Mitt. and Fissidens spp. Conservation status. This species is not under immediate threat, due to many populations being found in India and northern Thailand, with the extent of occurrence (EOO) of over 900,000 km 2 and its occurrence in protected areas. According to the IUCN criteria, the conservation status of P. himalayensis is classified as Least Concern (LC). Specimens examined. India • Himachal Pradesh: Shimla, Jakhu Tample, 2 Oct 2012, Duckett et al. IW 1 (QFA); • Meghalaya: West Khasi Hills, Thipringsong Forest, Nongstoin, ca 1,636 m elev., 15 Sep 2000, A. P. Singh & M. Lal 208617 (LWG); • Uttarakhand: Almora, on way to Binsar, 1,969–2,272 m elev., 4 Oct 1991, V. Nath & A. K. Asthana 205348 C, 205359 B (LWG); Almora, on way to P. Nath, 2,500 m elev., 6 Oct 1991, V. Nath & A. K. Asthana 205380 (LWG); • Mussoorie, Dehra Dun, Wood Stock College, 2,121 m elev., 3 Oct 1977, S. Chandra 203378 B (LWG); • Dhanaulti, 2,121 m elev., 3 Oct 1977, S. Chandra 203385 (LWG); • Nainital, on the way of Kilbury, 1,818 m elev., 12 Sep 2001, A. P. Singh & V. Sahu 208943 (LWG); • Uttarkashi, Silkiara, 1,818 m elev., 15 Sep 1977, S. Chandra 203229 (LWG); • West Bengal: Darjeeling, Himalayan Mountaineering Institute Road, ca 2,060 m elev., A. K. Asthana & V. Sahu 224004 (LWG). Thailand • Chiang Mai: Chiang Dao, Angsalung base camp, 19°23'51.56"N, 098°53'21.08"E, 2,191 m elev., 11 Nov 2016, S. Chantanaorrapint & O. Suwanmala 651 (PSU), 29 Aug 2017, S. Chantanaorrapint & O. Suwanmala 2024 (PSU), 9 Oct 2019, S. Chantanaorrapint & O. Suwanmala 3875, 3876, 3877 (PSU), 13 Nov 2020, S. Chantanaorrapint & O. Suwanmala 4079, 4080 (PSU), 24 Nov 2022, O. Suwanmala 854, 856, 857 (PSU); • Doi Luang Chiang Dao, 2,169 m elev., 19 Dec 2011, S. Chantanaorrapint 2540 (PSU), 1 Nov 2013, S. Chantanaorrapint & C. Promma 3123, 3126, 3215 A (PSU); • the trail to Kew Lom, 19°23'33.36"N, 098°53'24.40"E, 1,937 m elev., 12 Nov 2016, S. Chantanaorrapint & O. Suwanmala 664, 695 (PSU), 28 Aug 2017, S. Chantanaorrapint & O. Suwanmala 2006 (PSU), 9 Oct 2019, S. Chantanaorrapint & O. Suwanmala 3880 A (PSU), 13 Nov 2020, S. Chantanaorrapint & O. Suwanmala 4081, 4082 (PSU); • Lam Phun: Khun Tan National Park, 18°29'40.18"N, 099°17'17.45"E. 1,092 m elev., 20 Aug 2022, S. Chantanaorrapint & O. Suwanmala 4474 (PSU); • Tak: Umphang, Thung Yai Naresuan, 19 Sep 2014, S. Chantanaorrapint 2756 (PSU). Taxonomic notes. Phaeoceros himalayensis is characterized by 1) the presence of tubers at the ventral and apical regions of the thallus, 2) the distal face of the spore covered by irregular verrucose projections, 3) the presence of a central depression on each proximal face, and 4) yellowish brown to dark brown sporophytes at maturity. Phaeoceros himalayensis resembles P. kashyapii in having irregular verrucae on the distal face of the spore, but it differs from the latter by the presence of a central depression on each proximal face. The sexual condition of P. himalayensis has been subject to different interpretations. Kashyap (1915) first described Anthoceros himalayensis (= P. himalayensis) as a dioicous plant with male and female thalli differing in size. However, Mehra and Handoo (1953) noted that it was monoicous but protandrous, based on their collections from Mussoorie, Simla, and Nainital in India. Proskauer (1967) and Asthana and Srivastava (1991) also stated that P. himalayensis was monoicous, while Chantanaorrapint et al. (2015) described it ambiguously as monoicous and dioicous. Based on specimens examined as part of this study, P. himalayensis is monoicous.

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