The new species resembles Selaginellaamblyphylla in habit and gross morphology, but it is different in stems and branches reddish (vs. stramineous in S.amblyphylla), ventral leaves ovate-oblong, 1.1–2.2 × 0.4–0.8 mm (vs. oblong, 2–3 × 0.6–1.2 mm), base subcordate, basiscopic margin not ciliolate (vs. rounded and margin sparsely ciliolate); dorsal leaves oblique subcordate or cordate at base (vs. obliquely cordate), margin with rather long cilia (vs. denticulate or ciliolate); axillary leaves ovate and decurrent at base (vs. ovate or triangular and obtuse to decurrent at base); strobili 3.2–4.0 × 2.3–3.5 mm (vs. 3.5–10 × 3.2–4.4 mm), ventral sporophylls margin ciliolate, dorsal sporophylls margin denticulate (vs. both sporophylls margin ciliolate).

CHINA, Yunnan Province, Yimen County, Longquan Forest Park, 9 Feb 2017, Yan-Mei Zhu 8158 (Holotype, PE!; isotype PE).

Plants terrestrial, evergreen. Main stems reddish, creeping or suberect, stems 15–25 cm long, 0.6–1.0 mm in diam., branches stramineous. Rhizophores restricted in basal part of main stems or at intervals throughout length of creeping stem and branches, borne on ventral side in axils of branches. Main stems branched from near base, slightly sulcate, primary branches 0.7–1.5 cm apart, secondary branches once or twice pinnately branched, leafy portion of main stem including leaves 6–8 mm wide at middle, ultimate branches 4–7 mm wide including leaves. Axillary leaves on main stems and branches symmetrical, ovate, 1.1–2.2 × 0.4–0.8 mm, at base decurrent, margin sparsely long ciliate at base, ciliolate or denticulate to the apex, apex acute. Dorsal leaves ± symmetrical, on main stems distantly, on branch imbricate, on main stem larger than on branches, ovate to broadly ovate, 1.2–1.9 × 0.5–1.0 mm, slightly carinate on abaxial surface, in base oblique subcordate or cordate, not peltate, margin ciliolate at base, apex long aristate, arista 0.3–0.6 mm long. Ventral leaves asymmetrical, slightly distant, on main stem bit larger than those on branches, ovate-oblong, 1.7–3.9 × 0.7–1.6 mm, in base subcordate; acroscopic base slightly overlapping stems and branch, margin long ciliolateat base, denticulate to the apex, basiscopic bases free from stems, margin entire, apex acute. Strobili compact, solitary, terminal on branch tips, dorsiventrally complanate, 3.2–4.0 × 2.3–3.5 mm. Sporophylls strongly dimorphic: dorsal sporophylls ovate-lanceolate, margin denticulate, apex acuminate, with sporophyll-pteryx slightly incomplete, margin denticulate, ventral sporophylls ovate-lanceolate, ascending, carinate, margin ciliolate, apex cuspidate. Megaspores white-yellow; proximal and distal surfaces verrucate, micro-sculpture densely echinate. Microspores yellowish, proximal and distal surfaces irregularly verrucate, micro-sculpture with interconnected and blunt spinules.

Dianzhong means central Yunnan in Chinese: the type locality (Yimen) is in the central Yunnan area which is centered on the Provincial capital city Kunming.

Selaginelladianzhongensis is known only from Yimen county, Yunnan, growing on mossy soils in a mixed evergreen forest, at ca. 1576 m a.s.l. (Fig. 3).

Selaginelladianzhongensis is known only from one locality inside the Longquan Forest Park in Yimen county, with more than 300 individuals. This park has a heavy recreational load and human pressure, and there are no specific measures to protect the habitats. Considering the restricted distribution and plausible threats, we tentatively assessed Selaginelladianzhongensis as vulnerable (VU) according to the IUCN (2018) categories and criteria.

Selaginellaamblyphylla Alston: THAILAND: Payar, Doi Angka, H. M. Smith 357 – BM [BM000779901, image online!] (holotype), – US [US00134348, image online!], MICH [MICH1191432, image online!], GH [GH00022032, image online!] (isotypes), Doi Cheng Dao, 4800 ft., on rock, Oct–Nov 1922, E. Smith 1262 – SING [!, image] (paratype); Udawn, 900–1400 m, Tagawa c.s. T-1816 [PE01622140]; CHINA:Yunnan, Mengla County, B. G. Li 48926 [PE00405395]; Zhenkang W. M. Chu et al. 15204 [PE00405401]; Yunnan, Gengma, W. M. Chu et al. 15279 [PE00405408]; Guangxi, Lingui, J. X. Zhong 808194 [PE01593730]; Yunnan, Simao (Szemao), ravine, 4000 ft., A. Henry 13529 – NY [NY00127369, image online!] (paratype). Selaginellabodinieri Hieron. Guizhou, Bijie, X. C. Zhang et al. 6842 [PE 01962745]; Guangxi, Fengshan, Alt. 750 m, X. C. Zhang 1272 [PE 00405447]; Selaginellakurzii Baker, Yunnan, Cangyuan, J. C. Zhao 2000-13 [PE 00405796]; Luquan, W. M. Chu 1649 [PE 00405795]; Mengla (Cha-li-Hsien), alt. 950 m, C. W. Wang 77750 [PE 01634093].