Tuesday, June 9, 2020

[Botany • 2020] Gymnosiphon syceorosensis (Burmanniaceae) • A New Species from Mt. Hamiguitan, Mindanao, the Philippines

Gymnosiphon syceorosensis Nickrent

in Nickrent, 2020.

A new holomycoheterotrophic member of Burmanniaceae, Gymnosiphon syceorosensis, is described from Mt. Hamiguitan located on the island of Mindanao, Philippines. This species differs from the recently named G. philippinensis from Cebu in a number of quantitative and qualitative characters. Phenetic (neighbor-joining) and phylogenetic (maximum parsimony) analyses of characters from Asian and Australian Gymnosiphon species were conducted and diagnostic taxonomic features were discussed. This new species appears to be most closely related to G. affinis J.J. Sm. from New Guinea but differs in a number of floral features including inner perianth lobe shape, stamen position in floral tube, and anther connective shape.

Keywords: Dioscoreales, Mindanao, monocot, Mt. Hamiguitan, mycoheterotroph

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.

Gymnosiphon syceorosensis Nickrent

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).

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).

 Daniel L. Nickrent. 2020. Gymnosiphon syceorosensis (Burmanniaceae), the Second New Species for the Philippines. PhytoKeys. 146: 71-87. DOI: 10.3897/phytokeys.146.48321