Selaginella subchaetoloma X.M.Zhou, Li Bing Zhang & Z.R.He, 2023

Fang, Shao-Li, Li, Yu-Xin, Zhang, Li-Bing, He, Zhao-Rong & Zhou, Xin-Mao, 2023, Selaginella subchaetoloma (Sect. Heterostachys; Selaginellaceae), a new species from Southwest China, Phytotaxa 603 (3), pp. 224-234 : 225-229

Selaginella subchaetoloma X.M.Zhou, Li Bing Zhang & Z.R.He , sp. nov. ( Figs. 1 , 3 )

Type: — CHINA. Yunnan: Zhaotong City, Qiao Jia County, Yao Shan Town , Jionglonggou , elev. ca. 1650 m, on ditch wall in Yunnan pine ( Pinus yunnanensis Franch. ) forest, 16 August 2002, Zhao-Rong He & Xing-Long Liu 29625 (holotype PYU-01001254 !; isotype PYU-01001255 !) .

Diagnosis: — Selaginella subchaetoloma is extremely similar to S. chaetoloma , but S. subchaetoloma has creeping sterile part and ascending fertile part ( Figs. 1A , 2A, B ) (vs. nearly creeping in S. chaetoloma ) ( Fig. 3D ), apex of dorsal leaves abruptly short-acuminate to submucronate ( Fig. 1D, J ) (vs. long aristate in S. chaetoloma ) ( Fig. 3G ), and ventral leaves slightly involute when dry ( Fig. 1C, E, I ) (vs. not involute when dry in S. chaetoloma ) ( Fig. 3I ).

Plants terrestrial, evergreen, ascending from decumbent base up to 12 cm ( Figs. 1A , 3A, B ). Rhizophores present only at middle and lower part of the main stem, borne on ventral side in axils of branches, 0.16–0.27 mm in diam. ( Fig. 1A & C ). Main stem pinnately branched, 0.25–0.46 mm in diam., terete; primary leafy branches 7 or 9 pairs, 3 times pinnately branched, adjacent primary branches on main stem 0.5–1.1 cm apart ( Figs. 1A , 3A, B ); ultimate branches of leafy portion of main stem 1.8–3.1 mm wide. Axillary leaves on branches symmetrical, ovate, 1.1–1.3 × 0.6–0.7 mm, base broadly cuneate, margin sparsely long ciliolate ( Fig. 1H ). Dorsal leaves asymmetrical, those on main stems not obviously larger than those on branches; dorsal leaves on branches not approximate or contiguous, obliquely oval, 1.2–1.6 × 0.9–1.0 mm, strongly carinate, base shallowly cordate, outside margin sparsely long ciliolate at base, denticulate upwards, inside basal margin entire below middle, ciliolate-denticulate to denticulate upwards, apex abruptly short-acuminate to submucronate ( Fig. 1D, J ). Ventral leaves asymmetrical, those on main stem not obviously larger than those on branches; ventral leaves on branches spreading or deflexed, ovate to broadly ovate, 1.5–2.2 × 0.9–1.2 mm, apex obtuse, base nearly rounded; basiscopic margin subentire or entire; acroscopic base enlarged, broader, slightly overlapping stem and branches, margin long ciliolate, cilia 0.10–0.50 mm; apical margin denticulate ( Fig. 1C, E, I ). Strobili solitary or binate, terminal, compact, dorsiventrally complanate, 4.0–6.4 × 1.5– 2.0 mm ( Figs. 1B , 3C ). Sporophylls dimorphic, indistinctly white-margined ( Fig. 1F, G ); dorsal sporophylls ovatetriangular, carinate, margin long ciliolate, apex acuminate, with sporophyll-pteryx complete and ciliolate ( Fig. 1K ); ventral sporophylls ovate, carinate, margin ciliolate; megasporophylls in basal portion on lower side of strobilus ( Fig. 1L ). Megaspores slightly yellow, spherical, 284–360 μm in diam., prominent laesurae extend 1/2–2/3 of the distance to the equator, both proximal and laesurae surfaces verrucate or vermiculate ornamentation covered with the reticulate microstructure ( Fig. 1M, N ). Microspores orange, hemispherical, 29.7–42.7 μm in diam., both the proximal and distal surfaces densely verrucate, without obvious microstructures ( Fig. 1O, P ).

Additional specimens examined (paratypes):— CHINA. Yunnan: Kunming City, Luquan County, Zehei Township , Guicheng Village , elev. ca. 1550 m, 6 May 1964 , W.- M. Chu et al. 1527 ( PYU); Wumeng Township , elev. ca. 2150 m, 7 May 1964 , W.- M. Chu, et al. 1649 ( PYU); Wumeng Mountain , elev. ca. 1900 m, 15 October 1964, W.- M. Chu & J.-L. Wu 2411 ( PYU) ; Wumeng Mountain, elev. ca. 2300 m, 15 October 1964 , W.- M. Chu & J.-L. Wu 2436 ( PYU); Lezuoni Village, elev. ca. 1900 m, November 1964 , W.- M. Chu & J.-L. Wu 3051 ( PYU); Zhaotong City , Qiaojia County, Chongxi Township , Mahong Village, elev. ca. 1500 m, 16 October 1991 , W.- M. Chu & H.-Z. Yan 24404 ( PYU); Qiaojiaying Township, Hetao Village, elev. ca. 2200 m, 5 August 2002 , W.- M. Chu & Z.-R. He 29610 ( PYU); Xiaohe Town , Yaoshan, Jionglonggou, elev. ca. 1650 m, 16 August 2002 , Z.- R. He & X .-L. Liu 29625 ( PYU) ; Sichuan: Ya’an City, Lushan County, elev. ca. 2000 m, 15 November 1963, S-H. Kung 3502 ( PYU); elev. ca. 1900 m, 15 November 1963, S-H. Kung 3503 ( PYU); elev. ca. 1800 m, 15 November 1963, S-H. Kung 3521 ( PYU); elev. ca. 1780 m, 18 November 1963, S .- H . Kung 3522 ( PYU); elev. ca. 1750 m, 18 November 1963, S .- H . Kung 3524 ( PYU); Luding County, Xinglong Town, Shima Village , Zhaizigou, elev. ca. 1700 m, 8 September 1981, S .- H . Kung 6282 ( PYU); Shimian County, Anshun Town, Xiaoshui Village , elev. ca. 1300 m, 11 November 1991, L .- B . Zhang & X.- S . Guo 2609 ( CDBI); Shimian County, elev. ca. 1200 m, 20 November 1991, L .- B . Zhang & X.- S . Guo 2697 ( CDBI) .

Habitat and geographical distribution: — This species is distributed from Central Yunnan to West Sichuan in China. It was observed to grow on ground and ditch wall in Yunnan pine forest or conifer-broadleaf forest at elevations between 1200–2300 m.

Etymology: —The specific epithet subchaetoloma derives from the Latin prefix sub-, somewhat, and chaetoloma , referring to the similarities between the new species and Selaginella chaetoloma .

Vernacular name: —áfṅǐł (jin mao bian juan bai).

Figures

FIGURE 1. Selaginella subchaetoloma.—A. Habit.—B. Ventral view of stems and branches with strobili.—C. Ventral view of portion of branches, showing rhizophores, axillary leaves, and ventral leaves.—D. Dorsal view of portion of branches, showing dorsal leaves.—E. Ventral view of portion of branches, showing ventral leaves.—F. Dorsal view of strobilus.—G. Ventral view of strobilus.—H. Axillary leaf.—I. Ventral leaf.—J. Dorsal leaf.—K. Dorsal sporophyll.—L. Ventral sporophyll.—M. Proximal surface of megaspore.—N. Distal surface of megaspore.—O. Proximal surface of microspore.—P. Distal surface of microspore (from the holotype: Z.-R. He & X.-L. Liu 29625).

FIGURE 2. Maximum likelihood phylogeny of Selaginella subchaetoloma and its allies based on molecular data. Maximum likelihood bootstrap support (MLBS) ≥ 50% and Bayesian inference posterior probability (BIPP) ≥ 0.50 are shown above the main branches; the dash (--) indicates MLBS <50% or BIPP <0.50; the asterisk indicates MLBS = 100 or BIPP = 1.00; omitted support values indicate both MLBS <50% and BIPP <0.50.

FIGURE 3. Morphology of Selaginella subchaetoloma (Z.-R. He & X.-L. Liu 29625) and S. chaetoloma (L.-B. Zhang 5909).—A–C. S. subchaetoloma A-B. Individuals.—C. Ventral view of strobili.—D–Q. S. chaetoloma, D. Individual.—E. Ventral view of strobilus.— F. Dorsal view of strobilus.—G. Dorsal leaf.—H. Axillary leaf.—I. Ventral leaf.—J. Dorsal sporophyll.—K. Ventral sporophyll.—L. Proximal surface of megaspore.—M. Distal surface of megaspore.—N. Detail of megaspore on distal surface.—O. Proximal surface of microspore.—P. Distal surface of microspore.—Q. Detail of microspore on distal surface. Scale bars = 0.5 cm (E & F), 0.5 mm (G-K), 100 μm (L and M), 20 μm (N), 10 μm (O & P), and 5 μm (Q).