Pyrrosia sarthalensis Sumit Singh, Sneha & Bikarma Singh, 2021

Singh, Sumit & Singh, Bikarma, 2021, Pyrrosia sarthalensis, a new species of Polypodiaceae from Kathua District, Jammu and Kashmir, Western Himalaya, India, Phytotaxa 522 (3), pp. 249-255 : 250-253

Pyrrosia sarthalensis Sumit Singh, Sneha & Bikarma Singh , sp. nov. ( Figs. 2–4 )

Diagnosis:— Pyrrosia sarthalensis is morphologically similar to P. flocculosa , but differs in smaller plant height, having basifixed, entire rhizome scales (vs. pseudopeltate, margin ciliate) and lacking hydathodes (vs. hydathodes present) ( Table 1 ).

Type: — INDIA. Jammu and Kashmir: Jammu Province, Kathua District, Bani Valley , 32.875° N, 75.804° E, elev. 1422 m, 2 September 2017, S . Singh & B. Singh 55259 (holotype: RRLH!; isotype: RRLH!) .

Epiphyte, 10–15 cm tall. Rhizomes shortly creeping, simple, unbranched, stout but elongated, sparsely scaly, grooved below between the roots, 2.5–3.1 mm diam., phyllopodia 0.5–0.8 mm apart, lateral buds situated to 1/3–1/4 down the phyllopodia; rhizome scales basifixed, 2.5–3.5 × 0.4–0.8 mm, broadly lanceolate, base entire, margin entire, acuminate towards apex, acumen slightly light brown; rhizome internal structure with the ground tissue parenchymatous, sclerenchyma sheath absent, sclerenchyma strands absent; vascular strands 5-8. Leaves (fronds) monomorphic, arise from the dorsal surface of the rhizome, distinctly stipitate; stipes 2–5 × 0.1–0.3 cm, light green, terete, pubescent when young, glabrous when mature; lamina simple, widest at or above the middle, 7–12 × 1.5–2.5 cm, base narrowed, apex acute, margin entire; main veins distinct, without secondary veins; included veinlets rare, simple, free, excurrent; hydathodes distinct, superficial to distinctly sunken; lamina ca. 0.2 mm thick; upper layer of the lamina with hairs, 1–2 mm diam., with spreading to appressed, acicular rays; lower lamina surface light green, woolly; indument on lower lamina surface dimorphic, a thin to dense mat, persistent, light brown or light grayish; composed of upper lamina surface with hairs ca. 1 mm diam., composed of 8–11 appressed acicular rays; lamina internal structure having upper epidermis with distinctly projecting cells with thin walls, hypodermis composed of a single discontinuous layer, palisade and spongy parenchyma distinct, lower epidermis with moderately thickened cell walls; stomata sunken, pericytic. Sori superficial, orbicular, scattered, restricted to the apical half of lamina, densely packed in 14 rows between midrib and margin, without a central bundle of paraphyses, developing simultaneously. Sporangia with stalks, as long as the capsule; capsules 0.3–0.4 mm high, 20 or 21 indurate annulus cells; spores yellowish, ovate to elliptic 70–80 × 40–50 µm, granulate.

Phenology:—Mature sori usually seen between September to November.

Etymology:—The species epithet is named after the type locality, i.e., the Sarthal Hill in the Bani Valley.

Distribution and Habitat:— Pyrrosia sarthalensis is found only in mixed subtropical forest of the Bani Valley, Kathua district, Jammu and Kashmir, India. Two localities from which this species collected were Sarthal camp and Bani valley. Pyrrosia sarthalensis observed as epiphyte whose distributional elevation range varies from 1400–1500 m above mean sea level. It grows on branches and trunks of host tree species such as Rhododendron arboreum Sm. (1805: 9) , Quercus oblongata D. Don (1825: 57) and Trema orientale [= Celtis orientalis L. (1753: 1044)] Blume (1856: 62) in the study area. Trunks and branches of these trees were found to be loaded with spongy mosses which cover the rhizomes of P. sarthalensis .

Conservation status:—The major threat to Pyrrosia sarthalensis is the unsustainable extraction of timber trees for construction and firewood. The tree species such as Rhododendron arboreum , Quercus oblongata and Trema orientale have been frequently used and are valued by local people in the valley. The local inhabitants mentioned the population of this epiphytic plant species has declined drastically in few decades. Deforestation, loss of habitat, overexploitation of associated natural resources, and illegal forest fires in the study area resulted in its population decline. The species is restricted to the Bani Valley of Kathua district, Jammu and Kashmir, India.

Discussion:— Pyrrosia sarthalensis is one of four species found in the western Himalaya. Other species are P. porosa [= Niphobolus porosus (C. Presl, 1836: 202) ] Hovenkamp (1984: 208), P. lanceolata [= Acrostichum lanceolatum L. (1753: 1067)] Farw. (1931: 245), P. flocculosa [= Polypodium flocculosum D. Don (1825: 1) ] Ching (1935: 66), and P. mannii [= Niphobolus mannii Giesenh. (1901: 107) ] Ching (1935: 55). Pyrrosia sarthalensis is part of the species clade that have short sclerified rhizomes, basifixed scales, and spores that are of homogeneous nature, and therefore, it belongs to the P. costata -group of Hovenkamp (1986). In P. flocculosa , the sori occur in 8 rows, whereas in P. sarthalensis the maximum number of rows recorded is 14. Apart from P. flocculosa , this species shows similar characters with other species of Pyrrosia such as P. costata [= Niphobolus costatus Wall. ex C. Presl (1836: 200) ] Tagawa & K.Iwats. (1967: 100) and P. stigmosa [= Polypodium stigmosum Swartz (1801: 21) ] Ching (1935: 67). The scales are basifixed and the acumen entire in P. costata , similar to P. sarthalensis . In P. stigmosa , scales are basifixed and fronds monomorphic like in P. sarthalensis .

Figures

FIGURE 2. Pictorial comparison of Pyrrosia sarthalensis with allied taxa P. flocculosa, (a) natural habit of P. sarthalensis on the trunk of Rhododendron arboreum, (b) close view fertile lamina with sori, (c) natural habit of P. flocculosa, (d) close view fertile lamina with sori (Photos: Bikarma Singh).

FIGURE 3. Holotype of Pyrrosia sarthalensis

FIGURE 4. Scanning electron microscope (SEM) micro-morphology of Pyrrosia sarthalensis displaying the structures of rhizome (a), lamina (b) and sporangia (c-d) (Courtesy: Kamlesh Singh, IIIM Jammu SEM/TEM Division).