Xiphopterella devolii (Polypodiaceae), a new species and newly recorded genus in Taiwan

Background Grammitid ferns are a tropical monophyletic clade nested in Polypodiaceae, containing more than 20 genera and more than 750 species. Many of them also grow in Taiwan. During the survey of recent two decades, an unknown grammitid fern was discovered and the taxonomic treatment is given herein. Results A new species, collected from Taiwan, is recognized and named, i.e., Xiphopterella devolii S. J. Moore, Parris, & W. L. Chiou. The holotype is deposited in TAIF, and isotypes are in HAST, K, L, US, and TNS. It is also distributed on SE & S China. The genus Xiphopterella is also a new record to Taiwan. Conclusion A new species, Xiphopterella devolii S. J. Moore, Parris, & W. L. Chiou is documented herein. The Xiphopterella is a new recorded genus in Taiwan and is first found beyond Malesia regions. Electronic supplementary material The online version of this article (doi:10.1186/1999-3110-54-24) contains supplementary material, which is available to authorized users.


Morphological study
Observations and measurements of trichomes and spores were based on specimens cited herein under different kinds of microscopes.

Spores
Mature spores of Xiphopterella devolii were collected from opened sporangia on the type specimen (SJ Moore 24567) and observed with a Leitz DMR light microscope under differential interference contrast (DIC). Diameters of 100 spores were measured. To increase the field depth of presented images, a series of photos were pictured under bright field (BF) with 2 μm focus intervals and merged by Helicon Focus 4.03 (Helicon Soft). Spore topology was observed with a scanning electron microscope (SEM). The spores were spread on a cover glass coated with Stay-on adhesive (Surgipath), coated with gold by IB-2 ion coater (Eiko Engineering), and observed with a TM3000 tabletop SEM (Hitachi). The backscattered electron (BE) images were photographed under 15 kV accelerating voltage.

Trichomes
Scales and hairs were also observed with a light microscope and SEM. To avoid damaging the type specimen (SJ Moore 24567), the whole specimens were observed under low vacuum mode of the SEM without pretreatment (i.e., fixation, dehydration, and coating).
About seven species in the world. They are mainly distributed on Malesia regions, especially Peninsular Malaysia (Parris, 2007). The discovery of this genus beyond Malesia regions is first documented here.
Xiphopterella Plants epiphytic. Roots filamentous wiry, ca. 0.2 mm thick; hairs simple, shiny to brick red, 0.2-0.5 mm long. Rhizomes radial; scales pale brown to brown, ovate to lanceolate, 1-2.5 mm long, ca. 0.5 mm wide, not clathrate, entire, glabrous. Stipes sessile or nearly so. Laminae linear, linear-elliptic, or linear-oblanceolate, 2-7 × 0.4-0.9 cm, acute at apex, attenuate to form a wing at base, simple, pinnatifid; pinnatifid segment inclined or ascending, widely to narrowly triangular, slightly oblique or falcate, up to 5 mm, entire, or rarely with a small blunt tooth at acroscopic margin; rachis prominent on abaxial side, grooved on adaxial side; lateral veins hidden, invisible, even by transmitted light, tip with a hydathode, simple in sterile segment, forked in fertile segment, acroscopic branch not extending beyond sorus; hairs transparent to pale, mainly on abaxial side of rachis and at base of laminae of young fronds, simple septate and 1 to 2 (or 3) forked with non-septate branches, the simple septate branch 0.1-0.2 mm long, 2-4 cells with an apical reddish club-like head, the lateral branch 0.2-0.3 mm long. Sori round to oval. Spores green, globose to tetrahedral-

Distribution and ecology
Taiwan and SE & S China. In Taiwan, it grows on tree trunks in dense moist forest; 1250-1350 m a.s.l.

Etymology
This new species is dedicated to Charles E. DeVol , a kind taxonomist who contributed to the research of Taiwanese lycophytes and ferns very much and was one of the editors for the Flora of Taiwan, 1st ed.

Discussion
This new species was first discovered almost 15 years ago when it was suspected to be Grammitis cornigera (Baker) Ching or even a new species of Xiphopteris (Chen 1998). The species Ctenopterella cornigera (Baker) Parris (syn. Micropolypodium cornigerum (Baker) X. C. Zhang) is endemic to Sri Lanka. Many Chinese specimens (eg., PE 24845, PE 1366173, PE 02114785, PE 02185396) identified as Micropolypodium cornigerum (or Xiphopteris cornigera (Baker) Copel. and Grammitis cornigera (Baker) Ching) are in fact this new species. The 'Grammitis sp.' in Knapp (2011) is attributed to this new species, too.

Conclusion
Through detail comparison with previous literatures and specimens in worldwide herbaria, a grammitid fern is confirmed to be a new species, i.e., Xiphopterella devolii S. J. Moore, Parris, & W. L. Chiou. Its types are designed and located herein. The Xiphopterella is a new recorded genus in Taiwan and is first found beyond Malesia regions.

Competing interests
The authors declare that they have no competing interests.
Authors' contributions SJM first found this new species and drafted the manuscript; BSP confirmed this new species and gave the taxonomic treatment; TTK carried out the light microscope and SEM observation of morphology and took photos; PFL gave more detail distribution of this species, provided habit and habitat photos, and corrected the drawing and text; WLC finished the manuscript and correspond this paper. All authors read and approved the final manuscript.