Lepisorus medioximus T.Fujiw., K.Hori & Khine, 2022

Fujiwara, Tao, Khine, Phyo Kay, Hori, Kiyotaka, Shin, Thant, Murakami, Noriaki & Schneider, Harald, 2022, Lepisorus medioximus (Polypodiales, Polypodiaceae), a new species from Shan State of Myanmar, PhytoKeys 201, pp. 23-34 : 23

Lepisorus medioximus T.Fujiw., K.Hori & Khine sp. nov.

Figs 2 , 3

Diagnosis.

The new species differs from similar species, Lepisorus elegans and L. contortus , by the combination of the following morphological characteristics: the lanceolate laminae with the widest at proximal 1/3 of the lamina, sori closer to costa, sori on distal 3/4 of the lamina, and ovate-lanceolate, ovate to orbicular clathrate paraphyses with entire margins. The species is discernible from L. tosaensis by pale-brown lanceolate rhizome scale with a narrow opaque band, remote fronds, and lanceolate leaf scales.

Type.

Myanmar. Shan state: Pin Laung Township, Ka Thaung upper, 19°57'58.5"N, 96°31'09.1"E, alt. ca. 904 m, 26 Sep. 2019, K. Hori, P.K. Khine [ “Kine”], T. Fujiwara, M. Nagashima, P.P. Shwe & A.K. Moe 108225 (holotype: MBK0328223!, isotype: HITBC! and RAF!) .

Description.

Plant epiphytic. Rhizomes long creeping, 0.10-0.15 cm in diam., densely scaly, sometimes naked when old; Rhizome scales lanceolate, pale-brown, iridescent, clathrate with short and narrow, dark brown, opaque center band, 2.1-2.8 mm long × 0.4-0.6 mm wide, margin entire to subentire, apex acuminate, lumina large. Fronds remote, up to 1.5 cm apart; stipe short, 0.4-0.8 cm long, 0.6-1.0 mm diam., straw to dark brown colored; Lamina lanceolate, abaxially grayish-green, adaxially light green when fresh, 8-16 cm long × 0.9-1.5 cm wide, widest at proximal 1/3 of lamina, thinly leathery, adaxially glabrous, abaxially sparsely scaly, lamina base attenuate, decurrent, apex long caudate; costa raised on both sides, veinlets obscure; Leaf scales lanceolate, brown, clathrate, 0.8-1.4 mm long × 0.1-0.3 mm wide, margin denticulate, apex acuminate; Sori on distal 3/4 of lamina, very close to costa, orbicular or elliptic, 0.17-0.35 mm long × 0.12-0.23 mm wide, occasionally sunken on abaxial side of lamina; Paraphyses ovate-lanceolate, ovate to orbicular, brown, clathrate, lumina large, margin entire, 0.19-0.28 mm in diam.

Etymology.

The epithet ' Lepisorus medioximus ' refers to the sori attached to the middle location on lamina.

Distribution.

This species is only known from the type locality in Myanmar, Shan state.

Habitat.

Epiphyte on tree trunks and branches in evergreen to sub-evergreen forest.

Additional specimens examined (paratypes).

Myanmar. Shan state: Pin Laung Township, Ka Thaung upper, 19°57'58.5"N, 96°31'09.1"E, alt. ca. 904 m, 26 Sep. 2019, K. Hori, P.K. Khine [ “Kine”], T. Fujiwara, M. Nagashima, P.P. Shwe & A.K. Moe 108229 (MBK 0328227!, HITBC! and RAF!) .

Note.

Until now, we have not discovered additional specimens from other localities despite our exhaustive search focusing on herbarium specimens collected in all parts of Myanmar and the Yunnan province of China. We specifically checked not only the Myanmar Lepisorus specimens deposited to the Makino Botanical Garden (MBK), the Institute of Botany, Chinese Academy of Sciences at Beijing (PE) and the Royal Botanic Gardens (K) but also the Lepisorus specimens of Dickason collection deposited in the United States National Herbarium (US), the Natural History Museum (BM), and Naturalis Biodiversity Center (L). Given the observation of more than 50 individuals of the species at the type locality, we expected this species to be abundant in this poorly collected area. Further inventories in Shan state and the adjacent areas should be necessary to find new localities of the species and evaluate the conservation status of the species. Reflecting our limited knowledge, the IUCN red list status of this species is given as "Data Deficient" instead of "Critical Endangered". The latter status would assume a restriction of this species range to the two localities recorded.

Figures

Figure 2. Living plant of Lepisorus medioximus T. Fujiw., K. Hori & Khine A habit B adaxial side of lamina C abaxial side of lamina with sori D rhizome scale E leaf scale F paraphyses.

Figure 3. Lepisorus medioximus T. Fujiw., K. Hori & Khine (holotype, Hori et al. 108225 = MBK 0328223) A habit B rhizome scale C leaf scale and D paraphyses.