Glaphyropteridopsis

Fawcett, Susan & Smith, Alan R., 2021, A Generic Classification of the Thelypteridaceae, Fort Worth, Texas, USA: BRIT Press : 42-43

GLAPHYROPTERIDOPSIS

Glaphyropteridopsis Ching, Acta Phytotax. Sin. 8:320. 1963. — Thelypteris sect. Glaphyropteridopsis (Ching) K. Iwats., Mem. Coll.Sci. Univ. Kyoto, ser. B, 31:29.1964.

— TYPE: Glaphyropteridopsis erubescens (Hook.) Ching [= Polypodium erubescens Hook. ]

For additional synonymy, see Ching (1963) and Holttum (1971).

Etymology.— From Glaphyropteris (Gr. glaphyros, hollow + pteris, fern) + -opsis, like. Ching (1963) alluded to the general similarity in frond size and blade dissection of Glaphyropteridopsis to Glaphyropteris (= Steiropteris in our treatment) in the Neotropics. However, these two genera are not closely related, as understood by Ching.

Plants terrestrial or on (among) rocks, medium-sized to large, 50–150(– 300 cm); rhizomes short and thick, sometimes massive, short-creeping or ascending, with sparse, ± glabrous scales at apices; fronds clustered or approximate, monomorphic, arching; stipes stramineous to tan, usually stout (2–)4–10+ mm diam., 30–100+ cm long, with sparse brown to tan, ovate, thin appressed scales at bases, with sparse acicular hairs or glabrescent; blades herbaceous, chartaceous or leathery, drying yellowish green to reddish brown, elliptic, with truncate bases (lacking greatly reduced pinnae), pinnate-pinnatifid, lacking pustules or glands, and generally lacking hairs between veins; rachises stramineous; pinnae sessile, opposite or subopposite, often large (to 50 × 5 cm in G. erubescens ), linear-lanceolate, deeply pinnatifid or nearly pinnatisect (incised within 1(–2) mm of costae), lowermost pinnae often narrowed at their bases, deflexed, costae grooved adaxially and sparsely to densely hairy abaxially; segments large, falcate-lanceolate, those at the base of the larger pinnae often somewhat elongate and/or toothed, and reflexed to overlap the rachis; aerophores absent at pinna bases or with only a small darkened patch in dried fronds; indument abaxially of sparse to dense acicular hairs along rachis, costae, costules, and veins, seldom with hairs between veins, glands (both sessile and stipitate) and scales lacking; indument adaxially of usually dense hairs along costal grooves, costules, veins, and tissue between veins usually glabrous; veins free, pinnate on segments, veinlets simple, to 25 pairs per segment, prominent and reaching margins, proximal pair running alongside transparent membrane below sinus or to sinus, or to margins just above sinus; pustules absent on laminar tissue; sori orbicular, exindusiate or with small indusia, these glabrous or with acicular hairs, subcostular and attached at bases of veinlets in a row on each side, close to or overlapping costules at maturity, usually confluent into a line when mature; sporangia glabrous or with hyaline setulae near annulus, these sometimes numerous; spores brown, elliptic, bilateral, irregularly reticulate-echinate, with perforations ( Tryon & Lugardon 1991) or with small tubercules on surfaces; x = 36. Two species counted, G. erubescens , both diploids and tetraploids, and G. rufostraminea , diploid.

Diagnosis.— Glaphyropteridopsis resembles Chingia in frond form and size, the truncate blade bases, and position of the sori, but the veins of the former are always free (vs. anastomosing below sinuses, except in C. pricei ). Scales of Chingia are bristly, numerous, and spreading (vs. appressed, tan, ovate in Glaphyropteridopsis ), and spores are sometimes reticulate and perforate (vs. echinate) ( Holttum 1971, 1982). All species of Glaphyropteridopsis except G. jinfushanensis have subcostular sori, a character that sets it apart from most other thelypterid species and genera, except for some species of Chingia ; however,this tendency for the sori to overlap the costules is most extreme in Glaphyropteridopsis . Another strong synapomorphy of the genus is the tendency to have strictly opposite or at least subopposite pinnae. This feature applies not only to the proximal pinnae but also to distal pinnae and is rather striking compared to the generally alternate pinnae (at least in the middle and distal parts of the blade) in most cyclosoroid genera. Species of Glaphyropteridopsis also resemble some neotropical Pelazoneuron spp. , just outside the large clade containing the former, but Pelazoneuron has medial sori, more substantial indusia, more lanceolate, spreading, hairy stipe base scales, alternate pinnae above the blade base, and cristate or echinulate spores, rather than the reticulate spores of Glaphyropteridopsis ( Patel et al. 2019a) . The superficial resemblance of Glaphyropteridopsis to certain species of Steiropteris (the subgroup Glaphyropteris), particularly S. decussata and allies ( Smith 1980), is not indicative of a close phylogenetic relationship; that species and relatives differ in having pronounced elongate aerophores, mucilaginous croziers, non-falcate segments with rounded apices, resinous laminar glands, and broadly winged spores.

Biogeography and ecology.— Glaphyropteridopsis is centered in, and nearly restricted to, South China, with all 11 known species occurring there, ten of them endemic, and several known only from the types or very few collections. The only species ranging outside of China is the type, G. erubescens , whose distribution extends into northern India, Nepal, Bhutan, northern Myanmar, Vietnam, Taiwan, and in Malesia only in the Philippines. The genus is absent from the rest of Malesia, Melanesia, and Polynesia, as well as Australasia and Africa and the New World. Species occur from 600–2000 m. They typically occur in forests or at forest margins, along streams, on rocks, or along roadsides.

Taxonomic and phylogenetic study. —Datasets based primarily on cpDNA sequences ( He & Zhang 2012; Patel et al. 2019a) and coalescent nuclear phylogenomic analyses (Fawcett et al. in press) infer Glaphyropteridopsis as sister to a large clade of strictly paleotropical cyclosoroids—including Amblovenatum , Chingia , Christella , Grypothrix , Menisciopsis , Plesioneuron , Pneumatopteris , Pronephrium , Pseudocyclosorus , Reholttumia , and Sphaerostephanos , but excluding Cyclosorus s.s. and also excluding all neotropical cyclosoroid genera, except Christella . However, a concatenated analysis of the same nuclear dataset (Fawcett et al. in press) places Glaphyropteridopsis within the chingioid subclade ( Chingia , Grypothrix , Menisciopsis , and Plesioneuron ; Fig. 1 ). Low or conflicting support along backbone nodes in plastid and nuclear analyses suggest that the precise phylogenetic position of this lineage be interpreted with caution.

Notes.— Ching (1963), when describing the genus, surmised that his G. eriocarpa and G. splendens could be of hybrid origin, since they were rare and came from the same locality as G. erubescens and G. rufostraminea . This hypothesis has not been tested. Shieh & Tsai (1987) described Thelypteris × erubesquirolica , which they believed to be a hybrid between Glaphyropteridopsis erubescens and Pseudocyclosorus esquirolii . This hypothesis needs re-examination.

About half of the known species are illustrated by Lin (1999). All necessary combinations have been made in Glaphyropteridopsis , by Ching (1963) and Lin (1999).

Constituent species.— Glaphyropteridopsis emeiensis Y.X. Lin ; G. eriocarpa Ching ; * G. erubescens (Wall. ex Hook.) Ching ; G. glabrata Ching & W.M. Chu ex Y.X. Lin ; G. jinfushanensis Ching ex Y.X. Lin ; G. mollis Ching ex Y.X. Lin ; G. pallida Ching ex Y.X. Lin ; * G. rufostraminea (Christ) Ching ; G. sichuanensis Y.X. Lin ; G. splendens Ching ; G. villosa Ching & W.M. Chu ex Y.X. Lin

Figures

FIG. 1. A synoptical treeillustrating relationships among genera of Thelypteridaceae based on Fawcett et al.(in press).