Gymnosiphon syceorosensis Nickrent, 2020

Nickrent, Daniel L., 2020, Gymnosiphon syceorosensis (Burmanniaceae), the second new species for the Philippines, PhytoKeys 146, pp. 71-87 : 71

Gymnosiphon syceorosensis Nickrent sp. nov. Figs 3 , 4

Type.

Philippines. Davao Region, Davao Oriental Province, Municipio San Isidro, Barangay La Union, Mt. Hamiguitan Range Wildlife Sanctuary, 6°43.819'N, 126°10.757'E, elev. 1184 m, 18 June 2019, Plants & Lichens of the Southern Philippines Survey no. 1314 (holotype: BRIT, isotypes: CMUH, SIU).

Diagnosis.

Similar to G. affinis J.J. Sm. s. str. but differing in the outer perianth lobe color (white and violet vs. pure white), inner perianth lobe shape (cuneate vs. obovate), stamen position in floral tube (just below inner lobe vs. below middle of perianth), connective shape (elliptical vs. quadrangular), and connective apex (not apiculate vs. apiculate).

Description.

Erect holomycoheterotrophic herb 5-10 cm tall, glabrous, achlorophyllous. Rhizome below ground, horizontal, cylindrical, 2-6 mm long, ca. 1.0 mm wide, with few short branches, covered in numerous patent, subulate scale leaves, 1-2 × 0.2-0.3 mm. Roots highly branched, contorted, 0.05-0.2 mm in diameter, lacking root hairs. Stems solitary or with a few basal branches, erect, purple, terete, 0.5 mm wide, internodes 0.3-1.5 cm long. Scale leaves sparse, spiral on stem, sessile, appressed, light tan, narrowly ovate, 1.5-2.2 mm long, base clasping ca. half the stem circumference, apex acute. Inflorescence terminal, bicincinnate (biparous cymose), terminal prophyll with two branches, each branch (peduncle) ca. 2.5 mm long, two-flowered, monochasial. Flowers erect, actinomorphic, mature buds ca. 6.0 mm long. Pedicel up to 1.0 mm long, floral bracts broadly ovate, 1.8-2.1 mm long, entire, apex obtuse. Outer perianth lobes (limbs) 3, valvate, light purple, ca. 2.0 mm long, outline (including central and lateral lobes) broadly ovate, central lobes narrowly ovate, apex acute, cucullate, lateral lobes induplicate in bud, not reaching apex of central lobe, margins somewhat crenate, wavy, undulate; floral tube white, 1.5 mm long, 1.5 mm wide, slightly constricted at junction with limbs; limbs circumscissile, caducous, separating from the top of the floral tube which persists on the fruit. Inner perianth lobes 3, inserted just below limb sinuses, cuneate, slightly folded lengthwise, ca. 0.3 mm long, apex truncate, mucronate. Anthers essentially sessile, inserted ca. 0.2 mm below insertion of inner perianth lobes, bilocular, tetrasporangiate, quadrangular in outline, ca. 0.7 mm wide; connectives narrowly elliptical in face view, projecting slightly above apex of thecae. Style cylindrical, ca. 1.8 mm long (including stigma), apical portion 3-lobed, ca. 0.7 mm wide, style branches ca. 0.3 mm long; stigma lobes hollow, funnelform, narrowly cordate (compressed laterally), ca. 0.2 mm wide, edge thickened, covered in minute papillae, apex lacking appendages. Ovary infundibuliform, ca. 2.1 mm long, 1.5 mm wide at apex, unilocular with three parietal placentae each bearing at their apices a prominent, spherical, 0.4 mm-wide gland. Fruit (immature) ca. 3.0 mm long (ovary portion), persistent floral tube cylindrical, ca. 2.3 mm long, bearing the remains of the stigmas and anthers.

Distribution, habitat, and conservation.

Gymnosiphon syceorosensis is only known from the type collected in the tropical upper montane rainforest of Mt. Hamiguitan, Mindanao. The plant was found along the trail at 1184 m elevation, ca. 1 air km south of the summit of Mt. Hamiguitan. The substrate was predominantly ultramafic. This forest has the highest number of endemic and threatened plant species among the five vegetation types surveyed by Amoroso and Aspiras (2011). The habitat where this plant was found also contained other mycoheterotrophs such as Burmannia lutescens (a new record for this species for the Philippines) and Sciaphila sp. ( Triuridaceae ). Association of different mycoheterotrophs in one local area was mentioned by Schlechter (1913) and Pelser et al. (2019). This phenomenon may reflect the ecological requirements of the fungi or the association of different plant species with one fungus ( Maas-van de Kamer 1998). The latter seems to be supported for Burmanniaceae where that family as well as Gentianaceae and Triuridaceae have been found associated with Glomerales and Diversisporales ( Hynson and Bruns 2010). Because only one population of G. syceorosensis was discovered, no estimation of its abundance or overall distribution can me made. It, like most Gymnosiphon species, is likely rare in nature, but because it is inconspicuous, it is likely undercollected. Until further work can be undertaken to determine how many populations of G. syceorosensis exist, the conservation status of this species should at this time be considered Data Deficient (DD) according to the IUCN (2019). Note that the DD category does not imply that the taxon is not threatened.

Etymology.

The specific epithet commemorates the Mt. Hamiguitan Range Wildlife Sanctuary. The word “hagímit” is Cebuano for "a small tree of primary forest with rough leaves: Ficus sp." ( Wolff 1972). Apparently the “g” and “m” consonants were switched (a common occurrence in Cebuano), thereby producing “hamigit”. Adding the suffix “-an” which mean "a place of" gives hamigitan, i.e. "a fig tree place" or "a place with a fig tree". When constructing the specific epithet for Gymnosiphon , the goal was to express "from fig-mountain". Fig-tree is translated to Latin as “syce” (συκη, feminine) and mountain as “oros” (όρος, masculine), thus giving “syceoros” ( Stearn 1992). Using one of the recommended adjectival endings for geographic epithets with a masculine termination yields " syceorosensis ".

It should be pointed that generic names derived from Greek that end in “-on” are often interpreted as neuter, however, according to ICN Art. 62.2, compound generic names take the gender of the last word in the nominative case in the compound. In this example, the Greek word element -siphon (σίφων) is masculine, thus the gender for all specific epithets of Gymnosiphon should be masculine. The type species was originally published by Blume (1827) as G. aphyllum (neuter), but this should be corrected to G. aphyllus (masculine).

Figures

Figure 3. Gymnosiphon syceorosensis sp. nov. A upper portion of the plant with a young fruit in the central position of the bifid cyme. The entire plant was ca. 10 cm high B closer view of the flower buds and young fruit C underground portion of the plant (fixed in alcohol) showing short rhizome with scale leaves, exogenous roots, and basal part of aerial stem D closer view of stem scale leaves E base of aerial stem where it emerges from the soil. Photos A, B, D, E by Michael Galindon. Photo C by DLN.

Figure 4. Gymnosiphon syceorosensis sp. nov. A bifid cyme (bicincinnate) showing older flower bud at top and young fruit below B fixed flower bud, sectioned longitudinally C closer view of the stigma flanked by two anthers D anther in longitudinal section (left) and in face view (right) showing position relative to inner perianth lobes E terminal portion of floral tube that is persistent on the fruit. Note the disintegrating stigma and anthers among the debris. All photos by DLN.