Dipteris shenzhenensis Y.H.Yan & Z.Y.Wei, 2021

Wei, Zuo-Ying, Gu, Yu-Feng, Xia, Zeng-Qiang, Chen, Li-Jun, Wang, Ting, Zhang, Shou-Zhou, Zhao, Guo-Hua, Chen, Jian-Bing, Cao, Jian-Guo & Yan, Yue-Hong, 2021, Dipteris shenzhenensis, a new endangered species of Dipteridaceae from Shenzhen, southern China, PhytoKeys 186, pp. 111-120 : 111

Dipteris shenzhenensis Y.H.Yan & Z.Y.Wei sp. nov.

Figs 2 and 3

Diagnosis.

The new species is similar to D. chinensis , but differs in rhizome scales being longer (6.8-8.0 mm vs. 3.74-4.00 mm), in the base and color of fronds (base with broad wings, abaxially pale vs. base without wings, abaxially green), and in stipe color (castaneous vs. stramineous to brown).

Type.

China. Guangdong Province: Shenzhen City, Mt. Qiniangshan , elev. ca. 82 m, 16 August 2020, Y. H. Yan et al. YYH15638 (holotype: SZG!; isotype: NOCC!)

Description.

Plants. terrestrial on rocks, 0.5-1.0 m tall. Rhizome. long-creeping, ca. 1 cm in diam., densely scaly. Rhizome scales. spreading, dark brown to black, stiff, margin almost entire, 6.8-8.0 × 0.09-0.27 mm, lanceolate, apex long acuminate, acumen up to 2-3 mm long; Stipe. glabrous except at the very base, castaneous, 30-85 cm. Fronds. slightly funnel-shaped, divided into 2 fan-shaped fronds, each half deeply divided into 4 to 5 unequal lobes, lobes shallowly divided one or more times, with 8-10 ultimate lobes in each half of lamina, abaxially glabrous and pale; base with broad wings; venation reticulate, visible on both surfaces, prominent abaxially. Lobes. margins serrate, apices acute, 4.5-12.0 × 10.5-17.0 cm, reticulated venation network. Spores. spreading, monolete, 18.5-19.0 × 37.5-39.0 μm, glabrous.

Distribution and habitat.

So far only known from Shenzhen City, Guangdong Province, southern China. It is distributed in Mt. Qiniangshan, growing on rocks at elevation of 70-200 m in evergreen broad-leaf forest.

Chinese name.

Shen-zhen-shuang-shan-jue (深圳双扇蕨).

Etymology.

Dipteris shenzhenensis was discovered in the City of Shenzhen located in Guangdong Province, southern China. The specific epithet, therefore, is from this city name.

Conservation status.

Dipteris shenzhenensis is currently found in only one location in Mt. Qiniangshan, Shenzhen City, Guangdong Province, southern China. The predicted Area of Occupancy (AOO) for the species is no more than 5,000 m2. This species prefers to grow in low and opening mountain areas and is very likely to experience human disturbance. Over the past 20 years, the authors have observed that D. shenzhenensis showed signs of decline with the recovery of macrophanerophytes in Mt. Qiniangshan. Following the International Union for Conservation of Nature (IUCN) Categories and Criteria ( IUCN 2019), we regard the newly discovered D. shenzhenensis as of Critically Endangered (CR) (B1a; B2ab).

Additional specimens examined.

China. Guangdong Province, Shenzhen City, Mt. Qiniangshan , elev. ca. 90 m, 16 August 2020, Y. H. Yan et al. YYH15637 (NOCC!) ; loc. cit., elev. ca. 200 m, 27 December 2003, Y. H. Yan 1937 (HUST!) ; loc. cit., elev. ca. 150 m, 8 November 2002, Y. H. Yan 885 (HUST!) ; loc. cit., 17 August 2002, S. Z. Zhang et al. 011036-A1 (SZG, photo!) ; loc. cit., elev. ca. 75.38 m, 18 November 2015, L. Jiang & Y. P. Chen JL00328 (KUN, photo!) ; loc. cit., elev. ca. 70 m, 22 February 2003, S. Z. Zhang et al. 012037-A (SZG, photo!) ; loc. cit., elev. ca. 70 m, 22 February 2003, S. Z. Zhang et al. 012037-B (SZG, photo!) ; loc. cit., 31 March 2000, F. W. Xing & Y. X. Zhang 12374 (IBSC, photo!). s. coll. 0685742 (IBSC, photo!)

Figures

Figure 2. Morphological features of Dipteris shenzhenensis Y. H. Yan & Z. Y. Wei (A-E) and D. chinensis (F-J). A fan-shaped frond of D. shenzhenensis B the frond base with broad wing of D. shenzhenensis C rhizome of D. shenzhenensis D spore of D. shenzhenensis E rhizome scale of D. shenzhenensis F fan-shaped frond of D. chinensis G the frond base without wing of D. chinensis H rhizome of D. chinensis I spore of D. chinensis J rhizome scale of D. chinensis.

Figure 3. Dipteris shenzhenensis Y. H. Yan & Z. Y. Wei A habit B details of a lamina showing the venation and the distribution of sori C rhizome scale showing the profile and length (drawn by Zuo-Ying Wei & Li-Jun Chen, based on the type material at SZG).