Gymnosiphon syceorosensis (Burmanniaceae), the second new species for the Philippines

Abstract

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.

Full text

Gymnosiphon syceorosensis (Burmanniaceae), the
second new species for the Philippines
Daniel L. Nickrent1
1 Department of Plant Biology, Southern Illinois University, Carbondale, 62901-6509, Illinois, USA
Corresponding author: Daniel L. Nickrent (nickrent@siu.edu)
Academic editor: Y. Mutafchiev|Received 8 November 2019|Accepted 11 March 2020|Published 8 May2020
Citation: Nickrent DL (2020) Gymnosiphon syceorosensis (Burmanniaceae), the second new species for the Philippines.
PhytoKeys 146: 71–87. https://doi.org/10.3897/phytokeys.146.48321
Abstract
A new holomycoheterotrophic member of Burmanniaceae, Gymnosiphon syceorosensis, is described from
Mt. Hamiguitan located on the island of Mindanao, Philippines. is species diers from the recently
named G. philippinensis from Cebu in a number of quantitative and qualitative characters. Phenetic (neigh-
bor-joining) and phylogenetic (maximum parsimony) analyses of characters from Asian and Australian
Gymnosiphon species were conducted and diagnostic taxonomic features were discussed. is new species
appears to be most closely related to G. anis J.J. Sm. from New Guinea but diers in a number of oral
features including inner perianth lobe shape, stamen position in oral tube, and anther connective shape.
Keywords
Dioscoreales, Mindanao, monocot, Mt. Hamiguitan, mycoheterotroph
Introduction
Mycoheterotrophs are plants that obtain nutrients from mycorrhizal fungi that are at-
tached to the roots of vascular plants as well as from saprophytic fungi (Leake 1994).
is trophic form occurs in ten angiosperm families, some of which are green and
photosythetic and are called partial mycoheterotrophs whereas others have little or
no photosynthetic activity and are called full mycoheterotrophs (Merckx et al. 2013).
ese conditions are analagous to hemi- and holoparasitic angiosperms. Because both
life forms can be found in various genera of Burmanniaceae (Dioscoreales) and even
PhytoKeys 146: 71–87 (2020)
doi: 10.3897/phytokeys.146.48321
http://phytokeys.pensoft.net
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Daniel L. Nickrent / PhytoKeys 146: 71–87 (2020)
72
among dierent species of Burmannia, this family provide an opportunity to study
the evolutionary origins of these trophic modes. Among the eight genera in the family
(Merckx et al. 2013; Burmanniaceae s. str., i.e. without ve genera now placed in is-
miaceae), Campylosiphon Benth., Burmannia L. and Gymnosiphon Blume have both
Neo- and Paleotropical members. e holomycoheterotrophic genus Gymnosiphon was
listed by Merckx et al. (2013) as containing 16 Neotropical, 8 African + Madagascan,
and 9 Asian species. Since that publication, two species have been added: G. philippin-
ensis Pelser, Salares & Barcelona (Philippines) and G. queenslandicus Gray, Mahyuni &
Low (Australia) bringing the total number of species to 35 (Gray et al. 2019; Pelser et
al. 2019). As pointed out by Pelser et al. (2019), most Asian species are rarely collected,
reecting either true rarity or the fact that these plants are often overlooked.
Field work on the Philippine island of Mindanao was conducted during June 2019
as part of a project funded by the National Science Foundation entitled “Plant Dis-
covery in the Southern Philippines”. One excursion included the Mount Hamiguitan
Range Wildlife Sanctuary, a UNESCO World Heritage site that contains many Philip-
pine endemic and endangered plant species such as Nepenthes copelandii Merr. ex Mac-
farl., Paphiopedilum adductum Asher, Rhododendron kochii Stein, and Shorea polysperma
Merr. (Amoroso and Aspiras 2011). During the course of general collecting, specimens
initially identied as Burmannia were obtained. Part of this collection was later de-
termined to be Gymnosiphon by the presence of an unwinged ovary with prominent
locular glands, parietal placentation, and a deciduous perianth limb. Merrill (1924, p.
251) excluded G. aphyllus from the Philippines and no other species were listed for the
archipelago. e recently named G. philippinensis Pelser, Salares & Barcelona (Pelser
et al. 2019), collected on limestone substrate in southern Cebu, is apparently the rst
documentation of this genus in the Philippines (Pelser et al. 2011 onwards). ose
authors concluded that this taxon represented a new species based on a manual com-
parison to the morphologies of other Asian Gymnosiphon species. A similar method
was used in Gray et al. (2019) for G. queenslandicus Gray, Mahyuni & Low.
e present study presents results from cladistic and phenetic analyses that were
used to assist the process of determining the distinctiveness of the Hamiguitan taxon
as compared to previously described species. Moreover, these data also provided infor-
mation about species boundaries in Gymnosiphon section Gymnosiphon Urb. is was
deemed necessary given the dierent taxonomic concepts for Asian and Australian
Gymnosiphon species as published by dierent authors over the past century (Fig. 1).
e matrices constructed included continuous (quantitative) and categorical (quali-
tative) characters and these were analyzed separately and in a concatenated matrix.
e separate analyses were conducted to determine if similar relationships emerged
no matter what the partition or method of analysis. Ideally, these morphological data
should be examined in the context of a molecular phylogeny of the species, but the
only published studies of this type (Merckx et al. 2006, 2008) sampled just one Asian
species (G. aphyllus Blume) among the 11 accessions included.

A Second Gymnosiphon for the Philippines 73
Figure 1. Species concepts over time in Asian and Australian Gymnosiphon. Names shaded with the same
color represent synonyms of the same species according to Jonker (1938). e two taxa named by Tuyama
(1940) were not included in this study. e synonymy of G. nana (nanus) is based upon World Plants
Online (2020).
Beccari
1878
Smith
1909
Blume
1827
Schlechter
1913
Jonker
1938
G. philippinensis
G. minahassae
G. oliganthum G. oliganthus
G. minahassae
G. neglectus
Pelser et al.
2019
Gray et al.
2019
G. queenslandicus
G. papuanus
Tuyama
1940
G. okamotoi
G. aphyllus
G. aphyllum
G. celebicum
G. nana
G. borneense
G. torricellense
G. papuanus
G. pedicellatum
Materials and methods
Field work
Flowering individuals of the Mt. Hamiguitan Gymnosiphon taxon were photographed
in situ. Collections were dried and pressed as herbarium vouchers (no. 1314) and tis-
sue was dried in silica gel for later DNA extraction and sequencing. A few individuals
were also placed in bottles containing 70% ethanol for later examination. Dissection
and photography of the xed tissues was accomplished with an Olympus SZH-10
stereomicroscope tted with a Leica MC190HD digital camera.
Character scoring
For comparisons with other Asian and Australian Gymnosiphon species, descriptions
and illustrations from the primary literature were examined. e taxa G. nanus (Fukuy.
& T.Suzuki) Tuyama from Orchid Island and G. okamotoi Tuyama from Republic of
Palau were not included because their protologues were obtained after manuscript
submission. From these a list of characters that appeared taxonomically useful was
compiled. e original observations for this study as well as information from the
literature were compiled in an Excel spreadsheet (Suppl. material 1: Table S1). ese
were mainly from (Jonker 1938, 1948) and Schlechter (1913) as well as the descrip-
tions of G. aphyllus by Beccari (1878) and Smith (1922). ree species (G. minahassae
Schltr., G. oliganthus Schltr., and G. pauciorus Schltr.) were only collected once thus
the taxon descriptions of Schlechter and Jonker (who examined the same specimens)
were consolidated. For G. anis J.J.Sm., G. aphyllus Blume and G. papuanus Becc., the
descriptions and taxonomic views diered among Blume, Schlechter and Jonker, thus,
they were considered separately (see Fig. 1).

Daniel L. Nickrent / PhytoKeys 146: 71–87 (2020)
74
Twelve continuous (i.e. quantitative) and 12 categorical (i.e. qualitative, discrete)
characters were used (Tables 1, 2, respectively). Schlechter (1913) provided both quan-
titative and qualitative characters in his descriptions, albeit not consistently for all
structures and species. Photographs of the six types used by Schlechter are available
for examination at BGBM (Berlin). ese images have sucient resolution to allow
some characters to be scored, e.g. lengths of scale leaves, owers, and fruits. Some data
were obtained for quantitative characters not explicitly mentioned in the literature by
extrapolating from drawings. is was justied because the sizes of some structures
(e.g. ower length) mentioned in the articles could be conrmed from the herbarium
specimen image. From the type photos, measurements were taken from as many struc-
tures as possible and the mean values recorded. e use of original author descriptions
to generate the categorical characters posed some diculties because each employed
dierent terminology. e following is a brief listing of the continuous (0–11) and
categorical (12–23) characters used in this study. For additional discussion of these
characters, see Suppl. material 2: File S2.
Table 1. Continuous characters 0–11 for Gymnosiphon taxa used in this study. Top line is currently
accepted name, bottom line is source of descriptive data and in some cases synonyms. e top number
represents the ln-transformed standardized range (0 to 10), the bottom number the observed range. Miss-
ing data are shown as “?”.
Taxa/Characters 0 1 2 3 4 5 6 7 8 9 10 11
G. anis J.J. Sm. 5.170 2.369 4.531 7.112 3.479 5.532 0.000 0.000 ? 0.000 3.856 2.609
(Jonker 1938) 2.398 0.916 1.099 1.253 1.946 1.253 0.916 0.470 ? 0.916 1.447 1.099
G. anis J.J. Sm. 5.170 6.915 1.123 3.673 3.479 4.950 8.480 4.563 0.988 5.305 10.000 0.000
(G. torricellensis Schlechter 1913) 2.398 1.118 0.693 0.693 1.946 1.194 1.504 0.924 0.668 1.131 1.668 0.956
G. aphyllus Blume 5.530 ? 5.827 7.112 6.280 4.008 8.797 5.621 ? 2.795 6.058 4.890
(G. borneensis Becc.) 2.442 ? 1.253 1.253 2.140 1.099 1.526 1.030 ? 1.030 1.526 1.224
G. aphyllus Blume 6.520 1.915 4.531 9.304 7.105 5.532 8.797 4.239 2.835 3.660 0.150 8.568
(G. pedicellatum Schlechter 1913) 2.565 0.896 1.099 1.609 2.197 1.253 1.526 0.892 0.756 1.065 1.314 1.426
G. aphyllus Blume 5.873 ? 5.332 10.000 7.578 5.245 7.655 3.861 0.773 9.669 0.000 10.000
(Smith 1909) 2.485 ? 1.194 1.723 2.230 1.224 1.447 0.854 0.658 1.308 1.308 1.504
G. aphyllus Blume 7.119 4.513 ? 7.933 7.885 5.532 8.480 4.073 ? 4.497 2.169 6.676
(Jonker 1938) 2.639 1.012 ? 1.386 2.251 1.253 1.504 0.875 ? 1.099 1.386 1.322
G. minahassae Schlechter 4.795 4.676 3.951 6.165 4.475 2.594 7.824 6.513 3.225 2.795 2.992 1.864
(Schlechter 1913) 2.351 1.019 1.030 1.099 2.015 0.956 1.459 1.118 0.775 1.030 1.416 1.058
G. neglectus Jonker 4.600 4.513 10.000 0.000 3.479 4.008 2.630 2.241 10.000 4.497 ? 2.609
(Jonker 1938) 2.327 1.012 1.749 0.095 1.946 1.099 1.099 0.693 1.099 1.099 ? 1.099
G. syceorosensis Nickrent 4.401 5.316 4.390 2.853 3.479 4.008 0.000 0.900 4.351 5.305 2.169 4.346
(G. sp. 1314, this ms.) 2.303 1.047 1.082 0.560 1.946 1.099 0.916 0.560 0.829 1.131 1.386 1.194
G. oliganthus Schlechter 2.341 5.551 2.998 6.165 0.000 0.000 4.854 7.862 0.445 0.000 2.169 1.022
(Schlechter 1913) 2.048 1.058 0.916 1.099 1.705 0.693 1.253 1.253 0.642 0.916 1.386 1.012
G. papuanus Becc. 4.401 4.513 5.204 0.000 4.475 2.206 10.000 7.862 ? 0.000 6.951 4.068
(Jonker 1938) 2.303 1.012 1.179 0.095 2.015 0.916 1.609 1.253 ? 0.916 1.558 1.179
G. papuanus Becc. 6.203 10.000 3.800 0.000 3.479 0.761 6.415 5.657 2.238 0.967 2.652 0.755
(G. celebicum Schlechter 1913) 2.526 1.256 1.012 0.095 1.946 0.770 1.361 1.033 0.728 0.956 1.404 0.997
G. pauciorus Schlechter 1.519 0.000 5.827 0.000 5.406 1.164 10.000 10.000 0.224 4.497 3.856 2.116
(Schlechter 1913) 1.946 0.811 1.253 0.095 2.079 0.811 1.609 1.466 0.631 1.099 1.447 1.072
G. philippinensis Pelser et al. 0.000 9.284 6.844 2.853 5.406 4.950 7.485 4.031 5.332 8.298 8.379 1.991
(Pelser et al. 2019) 1.758 1.224 1.374 0.560 2.079 1.194 1.435 0.871 0.875 1.253 1.609 1.065
G. queenslandicus Gray et al. 2.598 6.469 1.533 1.906 4.475 3.326 7.991 5.799 0.000 4.497 2.169 2.609
(Gray et al. 2019) 2.079 1.099 0.742 0.405 2.015 1.030 1.470 1.047 0.621 1.099 1.386 1.099
G. suaveolens (H.Karst) Urb. 10.000 6.469 0.000 9.304 10.000 10.000 5.850 0.187 1.202 10.000 9.736 7.853
(Maas-van de Kamer 1998) 2.996 1.099 0.560 1.609 2.398 1.705 1.322 0.489 0.678 1.322 1.658 1.386

A Second Gymnosiphon for the Philippines 75
0 Plant height (cm);
1 Leaf length (mm);
2 Floral bract length (mm);
3 Pedicel length (mm);
4 Flower length (mm);
5 Outer perianth lobe length (mm);
6 Floral tube length (mm);
7 Ratio oral tube to outer perianth lobe length;
8 Ratio outer perianth lobe length to width;
9 Ovary length (mm);
10 Fruit length (mm);
11 Persistent oral tube length (mm);
12 Inorescence type: (0) simple cyme, (1) bid cyme, (2) capitate;
13 Outer perianth lobe outline including marginal lobes: (0) orbicular, (1) broadly
ovate, (2) ovate, (3) rectangular, (4) broadly obtrulate;
Table 2. Categorical characters 12–23 for Gymnosiphon taxa used in this study. Top line is currently accepted
name, bottom line is source of descriptive data and in some cases synonyms. Missing data are shown as “?”.
Taxa/Characters 12 13 14 15 16 17 18 19 20 21 22 23
G. anis J.J. Sm. 0,1 ? 0 ? 1 0 3 1 1 0 1 0
(Jonker 1938)
G. anis J.J. Sm. 0 0 2 0 1 0 3 2,3 0 1 1 0
(G. torricellensis Schlechter 1913)
G. aphyllus Blume 1 ? 2 ? 1 ? 0, 1 0, 1 0 ? 0 0
(G. borneensis Becc.)
G. aphyllus Blume 1 3 0 1 1 1 2 1 0 3 0 0
(G. pedicellatum Schlechter 1913)
G. aphyllus Blume 0, 1 3, 4 0 1 1 ? 1 1 0 3 0 0
(Smith 1909)
G. aphyllus Blume 0,1 ? 0 ? 1 1 0, 1 0 0 1 0 0
(Jonker 1938)
G. minahassae Schlechter 0 3 2 1 0 1 1 1 0 ? 0 0
(Schlechter 1913)
G. neglectus Jonker 2 3 2 0 1 0 0 0 1 3 0 0
(Jonker 1938)
G. syceorosensis Nickrent 110011420300
(G. sp. 1314, this ms.)
G. oliganthus Schlechter 0 0 2 1 1 1 4 1, 2 0 1 0 0
(Schlechter 1913)
G. papuanus Becc. 0, 1 ? 0, 2 ? 0 1 0 ? 1 1, 2 1 0
(Jonker 1938)
G. papuanus Becc. 1 0 0, 2 0 0 1 0 1 1 2 1 0
(G. celebicum Schlechter 1913)
G. pauciorus Schlechter 0 1 2 0 0 1 0 1 1 2 0 0
(Schlechter 1913)
G. philippinensis Pelser et al. 1 2 1 1 0 0 0 0 1 0 1 0
(Pelser et al. 2019)
G. queenslandicus Gray et al. 1 0 0 0 1 1 3 3 1 0 0 0
(Gray et al. 2019)
G. suaveolens (H.Karst) Urb 1 4 0 0 0 1 4 1 1 2 0 1
(Maas-van de Kamer 1998)

Daniel L. Nickrent / PhytoKeys 146: 71–87 (2020)
76
14 Outer perianth lobe outline without lateral lobes: (0) ovate, (1) narrowly ovate, (2)
triangular;
15 Outer perianth lobe margin to apex: (0) below apex, (1) equal apex;
16 Outer perianth lobe margin: (0) entire, (1) crenate;
17 Outer perianth lobe color: (0) white, (1) violet;
18 Inner perianth lobe shape: (0) linear, (1) lanceolate, (2) ovate, (3) obovate, (4) cuneate;
19 Inner perianth lobe apex: (0) acute, (1) obtuse, (2) truncate, (3) 3-lobed;
20 Position of stamens in oral tube: (0) just below inner perianth lobe, (1) between
inner perianth lobe and ovary;
21 Connective shape: (0) quadrangular, (1) triangular, (2) forked, (3) elliptic;
22 Connective apiculate: (0) no, (1) yes;
23 Stigma appendages: (0) no, (1) yes.
Analyses
Sizes reported in the literature as ranges were converted to median values. Means were
calculated from original observations from the Hamiguitan samples as well as measure-
ments taken from the BGBM photographs. Data matrices containing the untransformed
data were constructed in Mesquite (Maddison and Maddison 2018) and exported as
Nexus and TNT (Tree Analysis using New Technology) les for downstream analyses
(Golobo et al. 2008; Suppl. material 3: File S3). e categorical characters were used
“as is” in later analyses whereas the continuous character mean values were natural log-
transformed [ln(x+1)] and range-standardized [xs = (x – min/max – min) × 10] as out-
lined in iele (1993) with Microsoft Excel. All characters were treated as unordered.
Uncorrected distances for the transformed continuous character matrices were gen-
erated using Mesquite. Neighbor-joining (NJ) was performed separately on this matrix
and the “as is” categorical character matrix using PAUP* (Swoord 2002). Maximum
parsimony (MP) analyses of the categorical data were conducted with PAUP*. e
neotropical species Gymnosiphon suaveolens was chosen as the outgroup for all analyses
because ancestral area analyses suggests the genus originated in the New World and
took a boreotropical migration route to the Old World (Merckx et al. 2008). MP
analyses of the continuous and concatenated (continuous plus categorical) data matri-
ces were conducted with TNT. e log-transformed standardized continuous charac-
ters were optimized as additive with Farris (1970) optimization. e search routine as
implemented in “aquickie.run” nds optimal scores 20 times independently by using
defaults of “xmult” plus 10 cycles of tree-drifting (Golobo 1999). For strict consensus
calculation, TBR (tree bisection reconnection) collapsing was used (Golobo and Far-
ris 2001). e direction and magnitude of change for the continuous characters was
determined by using the TNT command blength for each of the 11 characters. Bremer
(1994) support values (decay indices) were calculated which represent the dierence
(number of steps) between the score of the most parsimonious tree and the next most
parsimonious tree where the node in question is lost.

A Second Gymnosiphon for the Philippines 77
Results and discussion
e MP strict consensus tree from the concatenated continuous and categorical data
matrices analyzed with TNT (Fig. 2) contains clades with varying degrees of support
as measured by Bremer decay index values. e four Gymnosiphon aphyllus terminals
are present as a grade at the base of the tree. A well-supported clade (Bremer decay
index > 5 steps) is composed of G. aphyllus (G. borneensis Beccari) and all remaining
species. A clade composed of G. minahassae, G. oliganthus, G. pauciorus and the two
G. papuanus terminals is present, but with a Bremer index of < 1 step. Bremer support
was higher (> 3 steps) for the sister relationship between G. anis (G. torricellensis
Schlechter) and G. philippinensis. is clade was then sister to G. queenslandicus, but
with lower Bremer support. Finally, a well-supported clade (> 5 steps) was recovered
containing G. neglectus, G. anis Jonker and Gymnosiphon sp. 1314.
e above results can be compared to those obtained when the continuous and
categorical characters are analyzed separately using phenetic and MP methods (Suppl.
material 4: File S4). A number of relationships shown in Fig. 2 are recovered as clus-
ters (Suppl. material 4: File S4A) or clades (Suppl. material 4: File S4B) when the
continuous characters are analyzed separately. ese include the grade of G. aphyllus,
the clade of G. papuanus Becc. and G. pauciorus, the clade G. anis (G. torricel-
lensis) and G. philippinensis, and the clade of the new taxon Gymnosiphon sp. 1314
with G. anis J.J. Sm. and G. neglectus. e taxa G. minahassae, G. oliganthus, and G.
papuanus (G. celebicum Schlechter) emerged as a grade in the TNT analysis (Fig. 2)
but as a cluster or clade (Suppl. material 4: File S4A, B, respectively) when continu-
ous characters were analyzed alone. Analysis of the categorical characters separately
(Suppl. material 4: File S4C, D) resulted in topologies that diered substantially from
the TNT results (Fig. 2).
Overall, it appears that a greater contribution to the tree shown in Fig. 2 came
from the continuous, not categorical characters. Both NJ and MP analyses of this data
partition recovered similar groupings as compared with the concatenated dataset ana-
lyzed with MP in TNT. When apomorphies are plotted on the strict consensus tree,
the majority (60%) are autapomorphic (conned to the terminals). Of the 66 synapo-
morphies, only 11 are categorical characters. is study demonstrates that greater reso-
lution can be obtained by including continuous characters, which has been shown in
empirical studies (e.g. Hardy et al. 2008) as well as simulations (Parins-Fukuchi 2017).
e type species for the genus, Gymnosiphon aphyllus, may be the earliest diverging
member among the Asian species. e variation in descriptive data (Suppl. material1:
Table S1) probably results from dierent taxonomic terminology and interpretation
of the morphology as well as real polymorphism that exists among populations of
this widespread taxon. e rst explanation can be demonstrated by comparing the
descriptions of Schlechter and Jonker who both examined the same specimens. e
four G. aphyllus terminals did not form a clade with MP or a cluster with NJ in any of
the analyses. Jonker (1938) lumped G. borneensis Beccari and G. pedicellatus Schlech-
ter into G. aphyllus Blume (Fig. 1). Because of their weak association, further study

Daniel L. Nickrent / PhytoKeys 146: 71–87 (2020)
78
0,1,4,5,9
10
3.4
1.0
5.9
3.5
0.6
0.6
1.1
0.8
3.6
3.6
5.9
0.6
1.0
0,2,3,5,8,10,11
1,6,8,11,18
0,1,3,4,
5,7,10,
11,14
6,7,8,9
0,4,9,19
2,6,10
1,5,7,11,12
3,10,11
0,8
1,5,7,
9,13
0,1,2,4,5,6,7,9,10
0,1,3,
4,6,11
3,9,15,18,20
2,4,6,
7,8
1,6,13,19
2,3,8,12,18,19
1,5,9,10,
11,22
0,2,3,4,
6,10,11,
12,20
3,5,6,7,8,10,14
6,7,14
0,1,9,10,
11,18,19,20
0,1,2,3,
5,7,9,
10,22
3,15,20
1,2,4,6,
10,11
0,1,7,8,11,12
0,1,2,4,7,9
5,9,10,11
0,1,2,4,6,
7,8,9,13,14,
15,16,18,19
1,2,6,
7,11
G. aphyllus Blume
(G. borneensis Beccari)
G. papuanus Becc.
(G. celebicum Schlechter 1913)
G. papuanus Becc.
(Jonker 1938)
G. minahassae Schlechter
G. queenslandicus
Gray et al.
G. affinis J.J.Sm.
(G. torricellensis Schlechter 1913)
G. oliganthus Schlechter
G. pauciflorus Schlechter
G. syceorosensis Nickrent
G. affinis J.J.Sm.
(Jonker 1938)
G. neglectus Jonker
G. philippinensis Pelser et al.
G. aphyllus Blume
(Jonker 1938)
G. aphyllus Blume
(G. pedicellatum Schlechter 1913)
G. aphyllus Blume
(Smith 1909)
G. suaveolens (H.Karst.) Urb.
(Gymnosiphon sp. 1314)
(Jonker 1938)
(Pelser et al. 2019)
(Gray et al. 2019)
(Schlechter 1913)
(Schlechter 1913)
(Schlechter 1913)
(Maas-van de Kamer 1998)
Figure 2. Maximum parsimony cladogram derived from the concatenated continuous and categorical
data matrices. Below the currently accepted taxon names are the sources of descriptive data and in some
cases synonyms (see Suppl. material 1: Table S1). Numbers above branches are Bremer support values.
Numbers below the nodal branches are unambiguous synapomorphies that occurred on every tree. Char-
acters 0–11 are continuous, 12–23 categorical. For the continuous characters, increases are shown in bold,
decreases as underlined fonts. Taxon names follow Jonker (1938, 1948) plus two recently named taxa (G.
philippinensis and G. queenslandicus).
of original material from all of these taxa is required to justify any decision regarding
lumping or splitting. Because species boundaries cannot easily be determined from
morphology alone, a molecular phylogenetic study of all these taxa is required.

A Second Gymnosiphon for the Philippines 79
e clade composed of G. minhassae, G. oliganthus, G. papuanus and G. pauciorus
(Fig. 2) has nearly the same composition as the group formed from NJ of continuous
characters (Suppl. material 4: File S4A), with the exception that the latter contains G.
queenslandicus. Gymnosiphon pauciorus is sister to G. papuanus and that clade sister to G.
papuanus Becc. that was considered G. celebicum by Schlechter (Fig. 2). To avoid a para-
phyletic G. papuanus, one could lump G. pauciorus into G. papuanus or recognize three
species. Gymnosiphon pauciorus shares several features with G. papuanus (Suppl. mate-
rial1: Table S1), including characters states such as entire outer perianth lobe margins,
linear inner perianth lobes, the position of stamens in the oral tube and forked connec-
tives. Dierences that were used in the key by Jonker include the number of owers in the
inorescence, a meristic character not used here because of extreme variation and overlap.
For these two taxa, Jonker (1938) indicates “3-many” for G. papuanus and “1–3” for G.
pauciorus. Because the latter was collected only once (Schlechter 16653), this taxon
could represent a few-owered variant of G. papuanus. Interestingly, the species nearest
to G. pauciorus in the Jonker key was G. neglectus that occurs in a distant clade in Fig. 2.
Jonker (1938) combined G. torricellensis with G. anis, describing the type of the
former as “incomplete material but very probably belonging to this species.” With ref-
erence to G. torricellensis, Schlechter (1913) wrote (translated from German): “Of all
the species hitherto known from the monsoon area, the present one is well dierenti-
ated by the broad, slightly three-lobed petals, and by the anthers.” e description in
that work was complete (Suppl. material 1: Table S1) and analysis of this taxon with
the description of G. anis from Jonker (1938) results in the two being present in two
dierent clades (Fig. 2). is result was consistent across all partitions and analytical
methods. e two taxa dier in several taxonomic characters including outer perianth
lobe margin, inner perianth lobe shape and apex, position of stamen in oral tube,
connective shape, and ratio of oral tube to outer perianth lobe length. For this reason,
it seems prudent to maintain these two taxa as dierent species. e taxon Gymnosi-
phon okamotoi Tuyama was not included in these analyses; however, after examining
its description and illustration (Tuyama 1940), it is clear this species has strong anity
with G. anis and may even be conspecic with it.
e results of the present study agree with the assessment by Gray et al. (2019) that
Gymnosiphon queenslandicus is closely related to G. anis s. lat., which is reected with
the categorical but not the continuous characters. Although G. torricellensis occurs
together with G. philippinensis and G. queenslandicus, Bremer support for that clade is
relative low. Gray et al. (2019), who examined one of the type collections of G. anis
(Versteeg 1425) noted that the position of the stamens was illustrated incorrectly in
Smith (1909) and that they actually occur below the middle of the oral tube. is
character state also occurs in G. neglectus and G. philippinensis but not G. torricellensis
and Gymnosiphon sp. 1314. Whether this feature changes through oral developmen-
tal (bud through anthesis) should be investigated, although for G. anis, Jonker (1938
p. 31) says that even in very young buds there is still “lowly” insertion of the stamens.
Gymnosiphon sp. 1314 is clearly not conspecic with G. philippinensis because it
diers in many character states such as outer perianth lobe margin, ower color, inner
perianth lobe shape, position of the stamens in the oral tube, and length of the oral

Daniel L. Nickrent / PhytoKeys 146: 71–87 (2020)
80
tube relative to the outer perianth lobe. NJ and MP of the continuous characters and the
combined data analyses place it as sister to G. anis with good Bremer support, but this
relationship was not seen with analyses of the categorical characters. e unique com-
bination of character states justies describing the Hamiguitan taxon as a new species.
Taxonomy
Gymnosiphon syceorosensis Nickrent, sp. nov.
urn:lsid:ipni.org:names:77209567-1
Figs 3, 4
Type. P. 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 Philip-
pines Survey no. 1314 (holotype: BRIT, isotypes: CMUH, SIU).
Diagnosis. Similar to G. anis J.J. Sm. s. str. but diering in the outer perianth
lobe color (white and violet vs. pure white), inner perianth lobe shape (cuneate vs.
obovate), stamen position in oral tube (just below inner lobe vs. below middle of
perianth), connective shape (elliptical vs. quadrangular), and connective apex (not api-
culate vs. apiculate).
Description. Erect holomycoheterotrophic herb 5–10 cm tall, glabrous, achloro-
phyllous. 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 circum-
ference, apex acute. Inorescence terminal, bicincinnate (biparous cymose), terminal
prophyll with two branches, each branch (peduncle) ca. 2.5 mm long, two-owered,
monochasial. Flowers erect, actinomorphic, mature buds ca. 6.0 mm long. Pedicel up
to 1.0 mm long, oral 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 (includ-
ing 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; oral tube white, 1.5 mm long, 1.5 mm wide,
slightly constricted at junction with limbs; limbs circumscissile, caducous, separat-
ing from the top of the oral 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 inser-
tion 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,

A Second Gymnosiphon for the Philippines 81
Figure 3. Gymnosiphon syceorosensis sp. nov. A upper portion of the plant with a young fruit in the central
position of the bid cyme. e entire plant was ca. 10 cm high B closer view of the ower buds and young
fruit C underground portion of the plant (xed in alcohol) showing short rhizome with scale leaves, exog-
enous 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.

Daniel L. Nickrent / PhytoKeys 146: 71–87 (2020)
82
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 oral 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. Hami-
guitan, Mindanao. e plant was found along the trail at 1184 m elevation, ca. 1 air
km south of the summit of Mt. Hamiguitan. e substrate was predominantly ultra-
mac. is forest has the highest number of endemic and threatened plant species
among the ve vegetation types surveyed by Amoroso and Aspiras (2011). e 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. (Triuri-
daceae). Association of dierent mycoheterotrophs in one local area was mentioned
by Schlechter (1913) and Pelser et al. (2019). is phenomenon may reect the eco-
logical requirements of the fungi or the association of dierent plant species with one
fungus (Maas-van de Kamer 1998). e latter seems to be supported for Burmanni-
aceae 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 Decient
(DD) according to the IUCN (2019). Note that the DD category does not imply that
the taxon is not threatened.
Etymology. e specic epithet commemorates the Mt. Hamiguitan Range Wild-
life Sanctuary. e word “hagímit” is Cebuano for “a small tree of primary forest with
rough leaves: Ficus sp.” (Wol 1972). Apparently the “g” and “m” consonants were
switched (a common occurrence in Cebuano), thereby producing “hamigit”. Adding
the sux “-an” which mean “a place of” gives hamigitan, i.e. “a g tree place” or “a
place with a g tree”. When constructing the specic epithet for Gymnosiphon, the
goal was to express “from g-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
specic epithets of Gymnosiphon should be masculine. e type species was originally

A Second Gymnosiphon for the Philippines 83
Figure 4. Gymnosiphon syceorosensis sp. nov. A bid cyme (bicincinnate) showing older ower bud at top
and young fruit below B xed ower bud, sectioned longitudinally C closer view of the stigma anked by
two anthers D anther in longitudinal section (left) and in face view (right) showing position relative to in-
ner perianth lobes E terminal portion of oral tube that is persistent on the fruit. Note the disintegrating
stigma and anthers among the debris. All photos by DLN.
published by Blume (1827) as G. aphyllum (neuter), but this should be corrected to G.
aphyllus (masculine).
Acknowledgements
is work was supported by the Global Environment Facility through the United
Nations Environmental Fund, with the DENR-Biodiversity Management Bureau
(formerly Protected Area and Wildlife Bureau) as the implementing agency; the
Department of Science and Technology – Grant In-Aid and a grant from the U.S.
National Science Foundation Biodiversity: Discovery & Analysis program entitled
“Collaborative research: plant discovery in the southern Philippines” to DLN, P.W.
Fritsch and D.S. Penneys (DEB-1754697 and DEB-1754667). e author thanks
Victor Amoroso and Fulgent Coritico for eld work coordination. For their un-
daunted help in the eld, thanks go to Jorgen Abellera, Mescel Sarmiento Acola,
Joevine Caballero Nobleza, Yvonne Love Cariño, Peter Fritsch, Michael Galindon,

Daniel L. Nickrent / PhytoKeys 146: 71–87 (2020)
84
Alice Gerlach, Vanessa Handley, Lydia Marie Hicks, April Joie Lagumbay, Noel La-
gunday, Jef Mancera, Jennifer G. Opiso, Gordon McPherson, Noe Shaw Mendez,
Darin Penneys, McAndrew K. Pranada, Peter Quackenbush, Maverick N. Tamayo,
Danilo Tandang, and Aimanuelzon Yorong. For the issuance of a Gratuitous Permit
and transport permits we acknowledge the Department of Environment and Natural
Resources (DENR) – Region 11. All specimens were collected under the permit is-
sued to the National Museum of the Philippines and Gratuitous Permit XI-2019-21.
Helpful advice on data analysis was oered by Andy Anderson and Kevin Nixon.
Victor Amoroso and Vic Romero helped with the etymology of Hamiguitan. Special
thanks go to Roy Gereau and Kurt Neubig for nomenclatural advice and to Peter
Fritsch and Darin Penneys for useful comments on an early draft of the manuscript.
e incisive comments from Pieter Pelser, Vincent Merckx and an anonymous re-
viewer greatly improved the manuscript.
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Supplementary material 1
Original morphological data derived from the literature and, for Gymnosiphon
syceorosensis, from original observations
Author: Daniel L. Nickrent
Data type: statistical data
Copyright notice: is dataset is made available under the Open Database License
(http://opendatacommons.org/licenses/odbl/1.0/). e Open Database License
(ODbL) is a license agreement intended to allow users to freely share, modify, and
use this Dataset while maintaining this same freedom for others, provided that the
original source and author(s) are credited.
Link: https://doi.org/10.3897/phytokeys.146.48321.suppl1
Supplementary material 2
List of continuous and categorical characters used for the Gymnosiphon taxa, with
discussion
Author: Daniel L. Nickrent
Data type: statistical data
Copyright notice: is dataset is made available under the Open Database License
(http://opendatacommons.org/licenses/odbl/1.0/). e Open Database License
(ODbL) is a license agreement intended to allow users to freely share, modify, and
use this Dataset while maintaining this same freedom for others, provided that the
original source and author(s) are credited.
Link: https://doi.org/10.3897/phytokeys.146.48321.suppl2

A Second Gymnosiphon for the Philippines 87
Supplementary material 3
TNT matrix used in this study with 12 continuous and 12 categorical characters
Author: Daniel L. Nickrent
Data type: statistical data
Copyright notice: is dataset is made available under the Open Database License
(http://opendatacommons.org/licenses/odbl/1.0/). e Open Database License
(ODbL) is a license agreement intended to allow users to freely share, modify, and
use this Dataset while maintaining this same freedom for others, provided that the
original source and author(s) are credited.
Link: https://doi.org/10.3897/phytokeys.146.48321.suppl3
Supplementary material 4
Trees resulting from continuous and categorical characters analyzed separately us-
ing neighbor-joining (NJ) and maximum parsimony (MP) methods
Author: Daniel L. Nickrent
Data type: statistical data
Explanation note: File S4A. NJ tree of continuous characters. File S4B. MP clad-
ogram of continuous characters. File S4C. NJ tree of categorical characters. File
S4D. MP cladogram of categorical characters.
Copyright notice: is dataset is made available under the Open Database License
(http://opendatacommons.org/licenses/odbl/1.0/). e Open Database License
(ODbL) is a license agreement intended to allow users to freely share, modify, and
use this Dataset while maintaining this same freedom for others, provided that the
original source and author(s) are credited.
Link: https://doi.org/10.3897/phytokeys.146.48321.suppl4