Huperzia nanlingensis Y. H. Yan & N. Shrestha, 2014

Shrestha, Nawal, Xing, Fu-Wu, Qi, Xin-Ping, Yan, Yue-Hong & Zhang, Xian-Chun, 2014, Huperzia nanlingensis (Lycopodiaceae), a new terrestrial firmoss from southern China, Phytotaxa 173 (1), pp. 73-79 : 73-78

Huperzia nanlingensis Y. H. Yan & N. Shrestha , sp. nov. ( Figs. 1 & 2 A, B )

Affinis H. serrata (Thunb.) Trevis. , sed caulibus elatis, foliis purpuratis, heterophyllis; foliis sterilibus coriaceis, 20–30 mm longis, 3–5 mm latis, lanceolatis, serratis, crispis, purpuratis, fasciculatis vel verticillatis; foliis fertilibus subulatis, 2–3 mm longis, 0.5 mm latis, integris, reflexis; soris nephroideis, magnis, aggregatis differt.

Types: — CHINA. Guangdong: Ruyuan County, Nanling Natural Reserve , 1200 m, 4 November 2001. Y. H . Yan et al. 1051 (holotype: IBSC!, isotype: HUST!) . Hunan: Yizhang County, Mangshan Mountain Natural Reserve , 1100m, 31 May 2007, Y. H . Yan & B. R . Liu 0602026 (paratype: HUST!)

Plants terrestrial, 20–35 cm tall. Stem erect, ca. 3 mm thick, often with 1–3 branches, decumbent at base, upper portion with purple coloration. Leaves dimorphic, fertile and sterile zones distinct; tropophyll elliptic-lanceolate, 20–30 mm long, 3–5 mm wide, angled upward, leathery, glabrous on both sides, shiny green with purple coloration at the tip and base, costate, subverticillate and layered, usually deciduous at the basal part of the stem, apex acute, base cuneate, petiolate, margin serrate; sporophyll subulate, 2–4 mm long, 0.5 mm wide at base, arranged helically, sessile, reflexed, leathery, green, margins entire or slightly serrate, usually persistent near the base of the stem. Sporangia reniform, axillary, spicate, arranged helically. Spores fan-shaped in equatorial view, equatorial axis ca. 25.5 μm (22.3–28.5 μm), subtriangular in distal polar view, tricolpate, cavernulous, apertures slightly granulated, exine non-granular or nearly glabrous; trilete in polar view, polar axis ca. 23.6 μm (20.8–26.5 μm), slightly rugulate.

Additional specimens examined: — CHINA. Guangdong: Ruyuan county, Nanling Mountain Natural Reserve 1200-1400m, Y. H. Yan 2464, 2704 ( IBSC!), Y. H. Yan 2586 ( HUST!), Y. H. Yan & C. H. Li s.n. ( HUST!), F. G. Wang 443 ( IBSC!). Hunan: Yizhang county, Mangshan Mountain Natural Reserve 1100-1400m, Y. H. Yan & B. R. Liu YL 0602123 ( HUST!, PE!), Y. H. Yan & H. M. Zhang 2586 ( PE!, HUST!), M. G. Huang 11462 ( IBSC!), S. Q. Chen 2773 ( IBSC!), B. G. Li 116 ( IBSC!).

Ecology and Distribution: — Huperzia nanlingensis has only been found in the Nanling Mountains , which is located at the boundary of Hunan and Guangdong Province, China. It is therefore, endemic to the Nanling Mountains. It grows in humus-rich sandy soil under shady and moist floor of evergreen broadleaved forest at an elevation ranging from 1100–1400 m .

IUCN Red List category: —This species has been found to be collected extensively for the extraction of huperzine A like all other species of Huperzia ( Ma et al. 2005, 2006). Furthermore, the species has restricted distribution in the Nanling Mountains and has not been found so far from any other regions. Therefore we categorize H. nanlingensis as Critically Endangered (CR) based on IUCN Red List Categories and Criteria version 3.1 second edition ( IUCN, 2012).

Etymology: —The epithet nanlingensis refers to the Nanling Mountains in southern China from where the type specimen was collected.

Notes: — Based on the presence of numerous serrations in its leaf margin, we place Huperzia nanlingensis under H. sect. Serratae (Rothm.) Holub (1991: 92) [= Huperzia ser. Serratae Rothmaler (1944: 59) ]. The species belonging to this section are characterized by serrate or denticulate leaf margins. Zhang & Iwatsuki (2013) recognized 13 species for China and H. serrata is the only species that is morphologically similar to H. nanlingensis in this section. Morphometric analysis of fifteen quantitative characters (see Table 1) using Principal Component Analysis (PCA) clearly separated the samples of H. nanlingensis and H. serrata into two distinct clusters without any overlapping ( Fig. 3 ). The two distinct clusters of samples observed in the PCA scatter plot were found to be highly significant in the Discriminant Analysis (Wilk’s lambda = 0.032; P <0.001). The cross validated classification showed that 100% of the samples were correctly classified. The characters that were found to be significantly different (P <0.001) between these two groups were seasonal index, length of the sporophyll, width of branchlets at the narrowest point, number of teeth on one side of the tropophyll and number of teeth on one side of the sporophyll.

Scanning electron microscopy (SEM) studies on the five random samples each of H. nanlingensis and H. serrata showed non granular spores and nearly glabrous exine with shallow and wider fovea in H. nanlingensis . In contrast, the spores of H. serrata have densely granular exine with deeper and narrower fovea ( Fig. 4 : G–H). Similarly, the study of stomatal apparatus revealed the presence of poroid tubercle at the bottom of the stoma’s interior in H. nanalingensis compared to reticulate waxiness in H. serrata ( Fig. 5 : E–F).

Molecular data of the psb A- trn H intergenic spacer, the – rbc L gene and the - rpL 16 gene further separated the samples of H. serrata from those of H. nanlingensis with strong support (Yan et al., unpubl. data; available upon request to the authors). Representative specimens of two species were nested under separate monophyletic clades in the molecular tree.

On the basis of morphology, anatomy as well as molecular data it is clear that H. nanlingensis is different from H. serrata . Although the observed morphological differences between these two species are superficially subtle, H. nanlingensis can be distinguished from H. serrata on the basis of purple coloration at the tip and base of leaves, higher number of teeth (32.28 ± 3.30) on one side of the tropophyll, higher seasonal index value (6.59 ± 0.71) and slightly crispate leaf margins.

Figures

FIGURE 1. Huperzia nanlingensis sp. nov. A. Habit.B.Adaxial surface of trophophyll. C. Abaxial surface of trophophyll.D. Sporophyll. E. Sporangia. Drawn from Y. H. Yan 1051 (IBSC).

FIGURE 2. A.Typical habit of H. nanlingensis. B. Upper branches showing leaves and sporangia of H. nanlingensis. C. Upper branches showing leaves and sporangia of H. serrata.

FIGURE 3. PCA scatter plot of the first two components based on 15 morphological characters.

FIGURE 4. Spores of H. serrata and H. nanlingensis. Equatorial view of spore of A. H. serrata & B. H. nanlingensis. Distal polar view of spore of C. H. serrata & D. H. nanlingensis. Proximal polar view of spore of E. H. serrata & F. H. nanlingensis. Distal polar view of spore of G. H. serrata & H. H. nanlingensis. Scale bars: A–F, 5 μm; G, H, 1 μm.

FIGURE 5. Stomata of H. serrata and H. nanlingensis. The lower epidermis of the leaves showing stomata of A. H. serrata & B. H. nanlingensis. Individual stoma of C. H. serrata & D. H. nanlingensis. Interior of the stoma of E. H. serrata & F. H. nanlingensis. Scale bars:A, B, 150 μm; C, D, 10 μm; E, F, 1 μm.