Menisciopsis, (Holttum) S. E. Fawc. & A. R. Sm. (Holttum) S. E. Fawc. & A. R. Sm.

Fawcett, Susan & Smith, Alan R., 2021, A Generic Classification of the Thelypteridaceae, Fort Worth, Texas, USA: BRIT Press : 52-53

MENISCIOPSIS

Menisciopsis (Holttum) S.E. Fawc. & A.R. Sm. , gen. et stat. nov. — Pronephrium C.Presl sect. Menisciopsis Holttum,Fl. Males,Ser.2, Pterid.1(5):530.1982.

— TYPE: Menisciopsis lakhimpurensis (Rosenst.) S.E. Fawc.& A.R.Sm.

Thelypteris subg. Cyrtomiopsis K.Iwats., Mem. Coll.Sci. Kyoto Imp. Univ.,Ser, B, Biol.31:36.1964.

For complete synonymy, see Holttum (1977b, 1982; Lin et al.2013).

Etymology.—Gr. Meniscium + - opsis, like. The type species, M. lakhimpurensis , often has sori coalescent along arching cross veins (meniscioid).

Plants terrestrial, rheophytic or cremnophilous, small (<15 cm) to very large (> 2 m); rhizomes short-creeping, long-creeping, or forming massive erect caudices; fronds monomorphic and once-pinnate, erect, ascending, or pendent; stipes stramineous, dull brown, or reddish; stipe scales dull brown, broadly ovate-deltate to ovate-lanceolate; blades chartaceous to subcoriaceous, laminae sometimes drying reddish; pinnae entire, crenate, toothed, or shallowly lobed, proximal pinnae not or little reduced, distal pinnae gradually reduced, with conform or subconform frond apex; veins anastomosing, generally with several pairs united below the sinus, forming areoles; cross-veins generally more or less straight, excurrent veins free or continuous from one areole to the next, straight or zig-zag, vein endings reaching segment margins; aerophores absent or present at pinna bases as a darkened swelling of aerating tissue; indument abaxially lacking, or of sparse, short, hyaline acicular hairs, generally restricted to costae and veins; indument adaxially lacking, or with short hyaline acicular hairs restricted to costae, rarely on lamina between veins, scales sometimes present on costae; elongate orange resinous glands abaxially on veins in some species; pustules present or absent on laminar tissue abaxially and adaxially; sori inframedial, often along costae or costules, rarely coalescent along uniting cross-veins ( M.lakhimpurensis ), indusiate or exindusiate; indusia glabrous, and persistent, or shriveling at maturity; sporangia without setulae or glands; spores typically black, sometimes brown, with non-reticulate folds or short echinate crests ( Patel et al. 2019a); x = 36, two of seven spp. counted, only diploids known. A sterile triploid hybrid between M. cyatheoides and Christella dentata ( Christella × palmeri ) has been reported ( Wagner 1993), and is supported by phylogenetic data (Fawcett et al., in press). The type ( MICH!) resembles the tetraploid parent C. dentata , which presumably contributed 2/3 of the hybrid genome.

Diagnosis.— Grypothrix differs from Menisciopsis in the presence of hamate, or hook-shaped hairs, proliferous buds, and sometimes dimorphic fronds. Abacopteris differs in having setulose sporangia, and sori medial and discrete (vs. sori usually inframedial or coalescent in Menisciopsis ). Pronephrium differs in dimorphic fronds, generally smaller size, frond apex gradually reduced (non-conform), and indusia sometimes bearing yellow glands. The neotropical genus Meniscium differs in the frequent presence of proliferous buds in axils of proximal pinnae, aerophores lacking, sori generally coalescent along arching cross-veins, and sporangial capsules or stalks sometimes bearing setulae.

Biogeography and ecology.—Among the seven species recognized in this genus, one is restricted to the Philippines, another is distributed in Fiji, New Hebrides, and New Ireland ( Holttum 1977b, 1982), three are in the Hawaiian archipelago ( Palmer 2003), and two are widespread in continental South Asia—one of these, Menisciopsis penangiana , reaches elevations of 3600 m ( Lin et al. 2013), but its congeners are typically of low to middle elevations.

Taxonomic and phylogenetic studies.—Holttum described Menisciopsis as a section of Pronephrium ( Holttum 1982) , although within this section he recognized species we here transfer to Sphaerostephanos and Abacopteris . The three Hawaiian species were treated by Holttum (1977b) and Palmer (2003) as members of Christella . Iwatsuki (1964a, 1964b) treated Menisciopsis boydiae ( Fig. 5B ) in a new subgenus of Thelypteris , Cyrtomiopsis, based on its distinctive morphology and superficial resemblance to Cyrtomium ( Dryopteridaceae ). Based on molecular phylogenetic evidence (Fawcett et al. in press) the closest relatives to Menisciopsis are Chingia and Plesioneuron , and all three of these monophyletic genera are in turn sister to Grypothrix , which was treated by Holttum (1982) as another section of Pronephrium in subg. Menisciopsis .

Figures

FIG.5.A.Menisciopsiscyatheoides,Takeuchi1719 (UC),pinna lobes,abaxial view.B.M.boydiae,Baldwin116 (US),habit.C.Menisciopsisrubrinervis,Fawcett716 (VT), pinna,abaxial view.Abacopteris aspera,James 1693 (VT).D. pinna.E.pinna,abaxial view.