Phlegmariurus iminii Kiew, 2018

Kiew, Ruth & Kamin, Imin, 2018, Two new Phlegmariurus species (Lycopodiaceae) and one new combination from Peninsular Malaysia, PhytoKeys 96, pp. 99-110 : 100-101

Phlegmariurus iminii Kiew sp. nov. Figures 1 , 2

Type.

Malaysia. Pahang, Merapoh District , Gua Gunting. 30 May 2013, Imin et al. FRI 78296 (holotype KEP! barcode 235330; isotype SING!) .

Description.

Medium-sized, tufted epiphyte. Stems lax, pendulous, ca. 30 cm long, slender, terete, ca. 2.5-3 mm in diameter; branching dichotomously 4 times, branches equal. Leaves spaced 3-4 mm apart, arranged in two alternating subspiral whorls of three, ascending at ca. 40° to stem, sessile; lamina dark green, thin and papery, lanceolate, (7-)10 × 1.8-2 mm, base flat, cuneate, margin flat, entire, narrowed to a minutely apiculate apex, glabrous above and beneath; midrib distinct on both surfaces, prominent above, keeled beneath. Strobilus slender ca. 1 mm thick, branched once dichotomously near the base with a short stalk 8-14 mm long and branches ca. 20 mm long followed by a short 50-90 mm long section of stem with sterile leaves, terminating in a strobilus (20-)40-70 mm long. Sporophylls distinct from leaves, spaced along the axis, sessile, ovate, much smaller than leaves, 1.5-2 × 0.75-1 mm, keeled on outer surface, base rounded and concave around the sporangium, margin entire, apex acute. Sporangium broadly reniform, ca. 2 mm long and wide, creamy becoming yellow when mature. Spores isotetrahedral with convex margins, polar axis ca. 20 µm, distal surface minutely foveolate.

Diagnosis.

This new species belongs to the Phlegmariurus phlegmaria group of species in being a medium-sized epiphyte with pendent stems, flat leaves broadest at base with a distinct midrib and sporophylls much smaller than vegetative leaves. Amongst Peninsular Malaysian species, it is different from P. phlegmaria (L.) T.Sen & U.Sen and P. salvinioides in its narrower, sessile leaves, 7-9 × 1.8-2 mm, positioned at 40° to the stem (vs. broader, subpetiolate leaves 5-15 × 2-5.5 mm, perpendicular to the stem) and in its unbranched strobili (vs. much branched). While the distinction between P. phlegmaria and P. salvinioides (Herter) Ching tends to intergrade, P. iminii is distinct without any specimens of these two species resembling it. It is similar to P. pinifolius (Trevis.) Kiew in its narrow, sessile leaves but its leaves are less crowded and positioned at 40° to the stem (vs. crowded and perpendicular to the stem) and its strobili are short and unbranched (vs. long and branched from the base). It also superficially resembles P. banayanicus (Herter) A.R. Field & Bostok from the Philippines but that species has broader leaves narrowed to the base (usually 8-10 × 2-3 mm) that are perpendicular to the stem and has branched inflorescences. Phlegmariurus iminii is distinct from all these species by a combination of its narrow, sessile leaves positioned at 40° to the stem and its straight, short, unbranched strobili with sporophylls that are not strongly appressed to the stem (Table 1 ).

Distribution.

In Peninsular Malaysia, it is at present known only from the type locality, Pahang, Merapoh District, Gua Gunting. Ashley R. Field (pers. comm.) notes that the species is a target for plant collectors and it is in cultivation from parts of Thailand and other parts of Peninsular Malaysia from a variety of habitats, although we have not been able to locate it in commercial nurseries in Malaysia.

Provisional conservation status.

Critically Endangered (A1d, B2ab[iii,v]). Its only confirmed locality is a single karst limestone hill that lies outside the network of Totally Protected Areas and has been threatened by quarrying for cement and is surrounded by oil palm plantations that expose it to disturbance from agricultural activities, in particular by the practice of clearing vegetation by burning. The limestone flora occupies only 0.4% of land area but is biodiverse harbouring at least 14% of the Peninsula’s vascular flora ( Chin 1977), so it is particularly vulnerable to disturbance ( Kiew 1997). In addition, many of its species like Phlegmariurus iminii are known from less than five limestone hills ( Kiew et al. 2017).

Ecology.

The type specimen grew on a tree on a steep slope, slightly shaded near the summit of a limestone karst hill.

Etymology.

Named after Imin Kamin, Research Assistant In-Charge of the lycophyte and fern collection in the Forest Research Institute Malaysia Herbarium (KEP), who discovered this species.

Figures

Figure 1. Phlegmariurus iminii. A habit B strobilus C tip of strobilus with sporangia and sporophylls D portion of leafy stem E distinct midrib on upper leaf surface F section of leaf to show keel G top view of sporangium and sporophyll H spores. (Drawing by Mohamad Aidil Noordin from Imin et al. FRI 81470).

Figure 2. Holotype specimen (Imin et al. FRI 78296) of Phlegmariurus iminii Kiew.