Tectaria pentagonalis (Bonap.) K.L. Phan, 2021

Dong, Shi-Yong, 2021, Validation of the combination Tectaria pentagonalis (Tectariaceae), Phytotaxa 496 (2), pp. 213-214 : 213

Tectaria pentagonalis (Bonap.) K.L. Phan , comb. nov.

Basionym:— Leptochilus pentagonalis Bonaparte (1918: 158) .

= Hemigramma pentagonalis (Bonap.) C. Christensen (1934: 109) .

Type :— VIETNAM. Binh-Dinh Prov.: “Rivièr verte A Plateau de Anh-Khe”, Binh Khe, March 1910, Eberhardt 207 (lectotype, designated here, P-00636722!) .

In the protologue of Leptochilus pentagonalis, Bonaparte (1918) cited three specimens, Eberhardt 207, 207bis & 219 ( P). All these specimens are syntypes ( Turland et al. 2017, Art. 9.6). I have traced four sheets of these collections in herbarium P (the numbers 207 and 207bis each having one sheet and the 219 having two sheets), with each sheet containing both sterile fronds and strongly contracted fertile fronds. They are apparently congruent in morphology. Therefore, the Eberhardt 207 (P-00636722) containing well-developed fronds is here designated as the lectotype of T. pentagonalis .

Tectaria pentagonalis appears to be a distinct species in Tectaria , as there is not a morphologically comparable species in Vietnam and neighbouring areas. As Bonaparte (1918: 159) had noticed, this species has its sterile fronds similar to those of T. subtriphylla (Hooker & Arnott 1838: 256) Copeland (1907: 410) but differs in having strongly contracted fertile fronds. In comparison, T. subtriphylla is a species with monomorphic or slightly dimorphic fronds and is featured by the relatively slim, creeping rhizomes. Rhizomes of T. pentagonalis seem to be short, suberect. Tectaria pentagonalis is hitherto poorly known, as it is represented by only the three type specimens collected in 1910. Further investigations, especially field surveys in its type locality, are needed for more information about this species.