A new species of grass fern, Schizaea erecta (Schizaeaceae), from Dinagat Island, Mindanao, Philippines Amoroso, Victor B. Acola, Mescel S. Guiang, Maria Melanie M. Acma, Florfe M. Fritsch, Peter W. Coritico, Fulgent P. Phytotaxa 2023 2023-10-04 618 3 265 273 Amoroso & Coritico (2020: 60) Amoroso & Coritico 2023 [136,558,594,621] Polypodiopsida Schizaeaceae Schizaea Plantae Schizaeales 2 267 Tracheophyta species erecta sp. nov.    Type:— PHILIPPINES. Dinagat Island: Municipality of Tubajon, Paragua Forest, 10.29355°N, 125.58594°E,  65 m,  30 January 2023,  V. B .  Amorosowith F. P.  Coritico& M. M.   Guiang.3003( holotype PNH!, isotypes CMUH!, BRIT!).   Diagnosis:—  Schizaea erectaresembles  S. dichotomain having hairy rhizomes, dimorphic fronds, stipes with a t-shaped xylem strand, laminae fan-shaped and branching dichotomously, stomata hypocytic, sorophores pinnately arranged in 2 rows, and sporangia with long non-glandular hairs, but differs by having a rhizome with short-appressed brown hairs (vs. long, coarse brown hairs), the stipe longer and up to 26.6 cmlong with a narrow groove (vs. up to 20 cmlong and deeply grooved), fronds 3–5 times branching dichotomously (vs. 6–8 times branching), narrower ( 8–14 cmlong by 2.0– 4.5 cmwide), and consistently erect fronds (vs. 15 cmlong by 17 cmwide, not erect), sorophores up to 39 per stipe with 12–16 lobes alternately arranged (vs. up to 34 with 5–10 lobes oppositely arranged), and sporangia oblong with long white hairs (vs. reniform with brown hairs).   Description:—Terrestrial, 30–50 cmlong. Rhizomesshort creeping, 1.5–5.0 cm below ground, 0.3 mmthick, covered with persistent shiny brown appressed hairs 1–2 mmlong. Frondsdimorphic, crowded, irregularly branched; sterile fronds:erect, stipes distinct, 18.5–26.6 cmlong, base partly buried in ground, blackish and becoming light green in upper portion, slightly winged at middle to distinctly winged at apex, with shallow groove and scattered short hairs; laminae fan-shaped, 9–15 cmlong and each axis 1 mmwide, whole laminae 2–4 cmwide, costae distinct, branching dichotomously 3–5 times; fertile frondserect, stipes 11–27 cmlong, tetragonal in transection and distinctly winged in upper portion; lamina fan-shaped, 8–14 × 2.0– 4.5 cm, branching dichotomously 3–5 times, basal branch slightly flattened, 1–2 mmwide, distal branch up to 0.5 mmwide with scattered small projections (bases of glandular hairs). Sorophoresborn distally of each branch of frond, 5–12 mmlong, 24–39 per stipe, bearing 12–16 pairs of lobes, pinnately arranged in 2 rows and opposite in arrangement. Sporangiain two rows associated with long white non-glandular hairs, with opposite to alternate arrangement, loosely arranged at base and tightly packed in upper part, oblong with short stout stalk, brown, annulus apical, opening by a vertical slit. Sporesmonolete and reniform, 37 µm in diameter.   Etymology:—The specific epithet refers to the erect fronds of the species.  Suggested common name:— Dinagatgrass fern.   Distribution and habitat:—  Schizaea erectais known only from open habitat at 65 melevation. It grows as a terrestrial plant in colonies with rhizomes growing below the ground in ultramafic soil associated with plants such as  Dicranopteris linearis( Burman 1768: 235) Underwood (1907: 250),  Imperata cylindrica( Linnaeus 1759: 878) Palisot de Beauvois (1812: 165),  Pipersp.,  Pteridium aquilinum( Linnaeus 1753: 1075) Kuhnin Decken (1879: 11),  Pteris cretica Linnaeus (1767: 130), and  Smilaxsp.( Figure 5).  Conservation Status:— DinagatIsland was identified as a critical terrestrial conservation priority in the Philippines( Ong et al., 2002). Logging, mining, and land conversion threaten the entire island ( Haribon, 2004).  Schizaea erectais known only within the Paragua forest, Municipality of Tubajon, with an estimated number of 30 individuals growing in just one open area near agricultural land. The habitat is prone to land conversion because of nearby residential areas. Thus, we recommend listing the species as critically endangered based on its restricted population with ≤ 50 mature individuals and the extent of occurrence estimated to be ≤ 10 km 2(IUCN Standards and Petition Committee 2019).   Discussion: — Schizaea erectais most similar to  S. dichotoma, based upon descriptions of Holttum (1959)and Sofiyanti et al.(2019), and examination of JSTOR typeimages and Co’s Digital Flora of the Philippines( Table 1). The species share nearly the same height and the presence of hairs on their rhizomes. Their fronds are dimorphic with fan-shaped lamina which branch dichotomously, they both have hypocytic stomata, and they both possess two rows of sorophores. However, the new species differs from  S. dichotomain having rhizome hairs 1.0– 2.3 mmlong (vs. 2–3 mm) ( Figure 2B); sterile fronds branching dichotomously 4–5 times (vs. 6–8 times) ( Figure 2C). Further, the frond is consistently erect whereas that of  S. dichotomais not erect ( Figure 2A). The sorophore of  S. erectahas 12–16 pairs of lobes whereas  S. dichotomahas 5–10 pairs. The sporangia of  S. erectaare oblong whereas  S. dichotomahas reniform sporangia ( Figure 2G, H).   TABLE 1.Comparison of the morphological characters differentiating  Schizaea dichotomaand  Schizaea erecta.     Characters    S. dichotoma( Sofiyanti & Fitmawati, 2019)    S. dichotoma( Holttum, 1959)  Schizaea erecta  Height (cm)  ca.35–45 No data 30–50  Rhizome Short Creeping, 3–6 cm below surface of ground Short creeping, 0.3 mm thick, 1.5–5 cm below the surface of ground  Rhizome hairs Present Present, coarse shiny brown, 2–3 mm long Present, shiny brown, appressed, 1–2 mm long, covering entire rhizome   Sterile frond  Length of stipes (cm)  ca.15–20 No data 18.5–26.6  Wing of stipes Not winged No data Slightly winged at the middle to distinctly winged at the apex  Size of lamina (cm)  ca.15 × 17 No data 9–15 × 2–4  Branching of lamina Dichotomously 6–8 times No data Dichotomously 4–5 times   Fertile frond  Length of stipes (cm) Up to 20 15–30 (extremes 10–50) 11–27  Winged stipe Narrowly present Narrowly winged towards apex Distinctly winged towards apex with two grooves  Lamina orientation Not erect No data Erect  Size of lamina Up to 35 cm long 10–20 cm long & wide 8–14 cm long & 2–4.5 cm wide  Branching of lamina Dichotomously 6–8 times Dichotomously 2–8 times Dichotomously 3–5 times  Basal branches No data Like stipe Slightly flattened, 1–1.5 mm wide  Distal branches No data Wings gradually wider, 1.5 mm wide, lacking prominent costa on lower surface Flattened, up to 0.5 mm wide, costa slightly prominent   Sorophore  Length of sorophores No data Occupying the distal 3–5 mm of each branch of frond Occupying the distal 5–12 mm long of each branch of frond  No. of sorophores Up to 34 per stipe No data 24–39 per stipe   Lobes of Sorophore  No. of lobe pairs 7 5–10 12–16  Arrangement of lobes Pinnate, alternate No data Opposite   Sporangia  Stalk No data No data Short stout stalk  Shape and color Reniform No data Oblong, brown  Annulus position No data No data Apical annulus  Arrangement No data No data Opposite to alternate, loosely arranged at the base and tightly packed in upper parts  Hairs No data Long, brown hairs Conspicuous long-white hairs  Ke et al. (2022)and Brownsey & Perrie (2014)stated that the  S. dichotomacomplex exhibits wide morphological and cytological variation. However, most members of this complex are poorly characterized and have been collectively lumped into “  S. dichotoma”, which was found to be polyphyletic in the phylogeny of Ke et al.(2022). Although our new species was not included in this phylogeny, we reckon that it is morphologically so distinct that it merits treatment as a separate species, especially in anticipation of further splitting in this group. With the recognition of this new species, there are now 21 species of  Schizaeaworldwide (PPG I, 2016) and three in the Philippines. The salient anatomical features of  Schizaea erectainclude the following: the rhizome is almost circular with appressed hairs as outgrowths of the epidermal cells. The cortex is mainly composed of parenchyma cells. The stele is a haplostele with the phloem surrounding the xylem tissue ( Figure 3B). The stipe shape changes from tetragonous at the base with indistinct costa and concave with narrow groove at the middle and somewhat flattened in the upper stipe with two distinct grooves and wings. The cortex becomes complex, being composed of the outer cortical sclerenchyma and the inner cortical parenchyma cells with the stele becoming actinostele and with a T-shaped xylem strand ( Figure 3C–E). The lamina is flattened at the lower axis with distinct costa and incurved at the apical axis. The outer wall of the smaller epidermal cells is thickened and inwardly with large hypodermal cells. The vascular bundle is surrounded by a layer of large endodermis and a single layer of pericycle as also reported by Sofiyanti et al.(2019). Moreover, both surfaces of the costa have large sclerenchyma cells to protect the inner undifferentiated mesophyll from drying as the plants are found in open area. The guard cells protrude on the abaxial surface of the epidermis and connect to the large intercellular spaces. The anatomy of  Schizaea erectadiffers from that of  S. dichotomain the rhizomes for having larger outer cortical cells and smaller inner cortical cells (vs. smaller outer cortical cells and larger inner cortical cells), vascular bundles surrounded by ring-like sclerenchymatous cell layers (vs. star-shaped sclerenchymatous cell layers), numerous metaxylem (vs. 4 metaxylem); stipe tetragonous at the base and flattened in the upper stipe with narrow groove (vs. M-shaped and deeply grooved); lamina narrowly grooved (vs. deeply grooved), and guard cells protruding from the abaxial surface (vs. guard cells sunken). [136,1448,668,690] 2023-01-30 V, B Philippines Type 65 10.29355 Municipality of Tubajon 1 125.58594 Island 2 267 1 Dinagat Islands [189,361,704,725] F, P Philippines Amoroso 2 267 1 Dinagat Islands [370,529,704,725] M Philippines Coritico 2 267 1 Dinagat Islands [538,1092,704,726] PNH, CMUH, BRIT Philippines Guiang. 2 267 1 Dinagat Islands holotype