Porella obtusata ( Taylor 1846: 380 ) Trevisan (1877: 407) var. macroloba (Steph.) Hattori and Zhang (1985: 325)

Sukkharak, Phiangphak & Chantanaorrapint, Sahut, 2018, An account of the liverwort genus Porella in Thailand with a new record, P. obtusata var. macroloba and the occurrence of asymmetrical underleaves associated with left-right symmetry in the genus, Phytotaxa 385 (2), pp. 77-84 : 81

10. Porella obtusata ( Taylor 1846: 380) Trevisan (1877: 407) var. macroloba (Steph.) Hattori and Zhang (1985: 325) . Madotheca macroloba Stephani (1910: 292) . Lectotype (designated by Grolle 1975): INDIA. Uttarakhand: Dehradun, 79°18’ 36’’E 30°3’N, 1800–2100 m, October 1879, Duthie s.n. (lectotype, G). Figure 1 .

Plants sterile, flaccid, pinnately branched, microphyllous branches absent, yellow to brownish yellow. Stems with leaves up to 5.4 cm long × 1–3 mm wide. Rhizoids fasciculate from the underleaf base. Leaves imbricate; leaf lobes convex with strongly recurved apex, ovate, 1–1.5 mm long × 1–1.4 mm wide, apex rounded to acute, dorsal base decurrent down, margins entire or with tooth of one cell at dorsal base; marginal cells 11–21 × 8–15 μm, median cells 18–30 × 16–25 μm, basal cells 30–49 × 16–35 μm, walls thin, trigones confluent, ocelli absent, oil bodies not seen; leaf lobules ovate-triangular, 0.6–1 mm long × 0.4–0.8 mm wide, apex obtuse, margins entire. Underleaves imbricate, orbicular, 0.5–0.7 × 0.5–1.2 mm, apex truncate, margin entire, bases auriculate, one auricle larger than the other, on right-hand branches the larger auricle occurring on the left side and on left-hand branches on the right-hand side, underleaf bases free, apex toward margins recurved. Gynoecia not seen. Androecia not seen.

Additional illustrations:— Hara (1956, p. 16, Fig. 4 (13–14) as Porella shikokiana Hara (1956: 16)) ; Hattori (1970, p. 82–84, Fig. 28 (12–26) as P. thuja ( Dickson 1801: 19) Moore (1877: 618) fo. ovalis (Gottsche ex Stephani 1910: 292) Hattori (1970: 82); p. 84–86, Fig. 28 (1–11, 27–33) as P. thuja fo. macroloba ( Stephani 1910: 292) Hattori (1970: 84)) ; Hattori (1978, p. 94, 106, Fig. 1. m ).

Ecology: In Thailand, Porella obtusata var. macroloba was found growing on rock and tree trunk at 1800–1889 m in lower montane rainforest.

Specimens examined:— Chiang Mai. CHIANG DAO WILDLIFE SANCTUARY: 19°23’40”N, 98°52’59”E, 27 October 2017, Sukkharak 91/1186 (Hb. Burapha Univ., PSU) ; 13 November 2016, Chantanaorrapint & Suwanmala 697 ( PSU) .

Distribution:— Porella obtusata var. macroloba has been reported in China (Taiwan), India, Japan ( Hattori 1978, Hattori & Zhang 1985, Gupta et al. 2018), and Thailand.

Taxonomic note:— Porella obtusata var. macroloba is distinguished from the rest of Porella taxa in Thailand by its entire leaves and underleaves. However, by these characters, P. obtusata var. macroloba approaches P. chinensis ( Stephani 1894: 218) Hattori (1967: 131) var. decurrens ( Stephani 1910: 289) Hattori (1978: 102) but differs from the latter in leaf lobules with plane margins (leaf lobules with strongly recurved margins in P. chinensis var. decurrens ).

Although the character was not described, the asymmetry of underleaves in this variety is shown in the illustration by Hattori (1970, Figure 28: 7, 21, 30–31, as Porella thuja fo. macroloba ) and by Gupta et al. (2018, Figure 12: 5–7). We have newly observed that the asymmetrical underleaves of P. obtusata var. macroloba occur in a distinct left-right symmetry pattern, the large auricle occurring on the left-hand side of underleaves on right-hand branches and on the right-hand side of underleaves on left-hand branches. The occurrence of asymmetrical underleaves has been reported in Colura ( Dumortier 1831: 32) Dumortier (1835: 12) ( C. usambarica Jones in Jones & Pócs (1987: 495), C. saroltae Pócs in Jones & Pócs (1987: 497)), Kurzia Martens (1870: 417) , Macrocolura Schuster (1994: 233) ( M. sagittistipula ( Spruce 1884: 304) Schuster (1994: 233)) , Telaranea Spruce (1885: 365) ex Schiffner (1893: 103) , and Thysananthus Lindenberg in Lehmann (1844: 24) ( T. frauenfeldii ( Reichardt 1866: 958) Sukkharak & Gradstein (2017: 101) and T. virens ( Ångström 1873: 131) Sukkharak & Gradstein (2017: 101)) ( Sukkharak & Gradstein 2014a, and references therein, Sukkharak & Gradstein 2014b, Wang & Zhu 2014, Sukkharak & Gradstein 2017). However, the asymmetry of underleaves associated with left-right symmetry has been reported only in Thysananthus ( Sukkharak & Gradstein 2014a, Sukkharak & Gradstein 2014b, Wang & Zhu 2014, Sukkharak & Gradstein 2017). Therefore, the asymmetrical underleaves in the left-right symmetry pattern found in P. obtusata var. macroloba is the first report of this apparently rare character in the genus Porella .

Figures

FIGURE 1. Porella obtusata (Taylor) Trevis var.macroloba (Steph.) S.Hatt. & M.X.Zhang. A. Portion of shoot, dorsal view. B. Portion of shoot, ventral view. C. Leaf lobes, ventral view. D. Leaf lobes and leaf lobules, dorsal view. E. Leaf lobes and leaf lobules, ventral view. F. Underleaves on right-hand branches, showing asymmetrical auriculate base. G. Underleaves on left-hand branches, showing asymmetrical auriculate base. H. Leaf apex. I. Margin cells of leaf lobe. J. Median cells of leaf lobe. K. Basal cells of leaf lobe. [All from Sukkharak 91/1186 (Hb. Burapha Univ.)].