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Aeginetia flava: a new and remarkable species of Aeginetia:
Orobanchaceae from South-Eastern Thailand
J. Parnell
1
Summary. A new species of Aeginetia so far only known from south-eastern Thailand, and related to the widespread
Aeginetia indica L., is described as Aeginetia flava.
Key Words. Christisonia, endemic species, SE Asia, taxonomy.
Introduction
Aeginetia is a small genus of Orobanchaceae whose
members all possess an unique apomorphy: a spatha-
ceous calyx. Beck-Managetta (1956) describes the
genus as containing four, five or possibly six species.
Two of these species, A. indica L. and A. pedunculata
(Roxb.) Wall., are well known and reasonably well
collected; other species are poorly recorded and
defined. All members of the genus have flowers which
are largely or entirely either red, purple or white or
some combination of these colours, with yellow being
confined to small patches within the corolla, if present
at all.
The accounts of the Orobanchaceae for the Flora of
Thailand (Parnell 2001,2008) include two genera,
Aeginetia and Christisonia, with a total of three species
between them. Aeginetia in Thailand comprises A.
pedunculata and A. indica. The latter species is very
common in Thailand as it is throughout South East
(SE) Asia and occurs in a wide range of habitats
including hill evergreen, bamboo, dipterocarp and
pine forests and by roadsides, on granite or limestone
substrata from sea level to 1,600 m. By contrast
A. pedunculata is rare, found only in deciduous
dipterocarp and bamboo forests, and grassland at
altitudes ranging from 50 to 1,100 m.
Aeginetia indica is morphologically variable, with
some plants being of more robust habit, with a
generally larger corolla ((2.5 –)4–5 cm), with a
larger degree of exsertion from the calyx (≥2/3); and
with considerable variation in flower colour (ranging
from white to dark purple).
Subsequent to the publishing of the accounts of the
Orobanchaceae for the Flora of Thailand (Parnell 2001,
2008) a new, attractive species in the genus Aeginetia
has been discovered in Chanthaburi province by Bob
Harwood and is described below.
Aeginetia flava J. Parn. sp. nov. Affinis A. indica sed
plantae flavae, caulis cum foliis 2 brevibus opposita
squamis simulans basaliter, corolla lobo explanato
dentate et semenibus testa reticulata minima.
Typus: Thailand, Chanthaburi, Khao Soi Dao Nuea,
1,400 –1,540 m, 26 Aug. 2008, Harwood 2013 (holotypus
TCD!; isotypus BKF!).
http://www.ipni.org/urn:lsid:ipni.org:names:77117182-1
Parasitic perennial herb. Stems all flowering, solitary
or branched near the base, 15 –20 cm tall; reddish-
yellow; with 2 opposite narrowly triangular, scale-like
leaves 10 mm by 2 mm towards the base. Flowers
solitary; buds ellipsoid. Calyx 2.5 –4cmlong,
spathulate, the tip erect to recurved; whitish yellow at
the base grading into pale pinkish at the tip; glossy.
Corolla 3.5 –5.5 cm long; 2.5 –4 cm of tube exserted
beyond calyx, exserted portion of tube down-curved or
± straight, somewhat dilated on emergence from calyx,
bright yellow; lower portion of concealed part of tube
strongly flexed, ± geniculate, forming a narrow throat
above the ovary, the throat somewhat dilated in its
mid-portion; lobes c. 0.5 –1 cm long, widely spread-
ing, slightly recurved at tips, markedly but shallowly
and irregularly dentate with the teeth c. 0.75 mm;
bright yellow; glossy externally. Stamens included,
massed together, attached ± at point of inflection of
corolla tube, point of attachment hairless; anthers with
1 cell perfect, dehiscence by ± apical pore-like slits;
upper stamens spurred and gibbous; lower gibbous
but only minutely spurred; spur with a terminal
conical projection at the tip; filaments of upper
stamens distinctly papillate near anther; filaments of
lower stamens ± smooth; anthers hairless. Style yellow,
curved; reaching nearly to top of corolla tube; stigma
yellow, included; peltate. Capsule c. 1.6 cm ×1 cm,
ISSN: 0075-5974 (print)
ISSN: 1874-933X (electronic)
Accepted for publication February 2012.
1
Herbarium, Department of Botany, Trinity Centre for Biodiversity Research, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland.
e-mail: jparnell@tcd.ie
KEW BULLETIN VOL. 67: 81 Y84 (2012)
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
Fig. 1. Aeginetia flava.Ahabit; Bback view of the spathaceous calyx and style; Cfront view of the spathaceous calyx; Dstyle and
the anthers in face view; Estyle and the anthers in side view. All from the type. DRAWN BY ELAINE CULLEN.
82 KEW BULLETIN VOL. 67(1)
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
ovoid, splitting near maturity; seeds ovoid 0.3 ×0.2 mm;
finely reticulate. Figs 1,2and 3.
DISTRIBUTION.Thailand: Chanthaburi province. Known
only from Khao Soi Dao Nuea and Khao Soi Dao Tai.
SPECIMENS EXAMINED. THAILAND.Aeginetia flava: Chan-
thaburi: Khao Soi Dao Nuea, on forest floor, 1,400 –
1,540 m, 26 Aug. 2008, Harwood 2013 (holotype TCD;
isotype BKF). A. indica: Loei: Phu Kradung, summit
plateau, trail from Than Sawan to Yhamsornue
Fig. 2. Photograph of Aeginetia flava in situ on Khao Soi Dao Tai. PHOTOGRAPH BY BOB HARWOOD.
Fig. 3. Aseed of Aeginetia flava from the type collection showing relatively small surface reticulations; Bseed of A. indica showing
relatively larger surface reticulations, seed extracted from Suddee 810 (TCD). IMAGES BY CLODAGH DOOLEY.
83AEGINETIA FLAVA: A NEW AND REMARKABLE SPECIES OF AEGINETIA
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
waterfall, 1,100 –1,200 m, 14 Sept. 1990, P. Chantaranothai,
J. Parnell, D. Simpson & K. Sridit 90/144 (TCD!); Phu
Kradung, summit plateau, Pen Pob Mai to park HQ,
1,100 –1,201 m, 13 Sept. 1990, P. Chantaranothai,
J. Parnell, D. Simpson & K. Sridit 90/209 (TCD!); Chiang
Mai: Doi Suthep, 1,000 –3,000 m, 22 Aug. 1909 A. Kerr
765 (TCD!); Doi Kar, Inthanon, 1,170 m, Oct. 1910,
A. Kerr 1515 (TCD!); Huai Mae Hia Luang, Doi Suthep-
Pui National Park, 900 m, 14 Sept. 1997, S. Suddee 840
(TCD!); Ubon Ratchathani: Yod Dom Wildlife Sanctuary,
4 Sept. 1997, S. Suddee 761 (TCD!) & 762 (TCD!),
Sakhon Nakhon: Phu Phan National Park, Kham
Hom Fall, 500 m, 9 Sept. 1997, S. Suddee 810 (TCD!).
A. pedunculata: Chiang Mai: Bo Luang, 850 m, 1958,
K. Larsen 5254 (BKF!); Lop Buri: Lam Narai, 50 m,
1975, T. Smitinand 12034 (BKF!) & . 12099 (BKF!).
HABITAT.In rainforest; alt. 1,400 –1,540 m. The
dominant upper storey tree probably being Quercus
semiserrata Roxb., with Pinanga sylvestris (Lour.) Hodel
very common in the mid-storey. An unidentified
Strobilanthes species dominates the ground layer, and
the several Aeginetia flava plants checked were all
attached to it via their root-system, and seem to be
parasitising that species.
CONSERVATION STATUS.The species was first found in
2008 and there is no information about its abundance
or distribution beyond Khao Soi Dao Wildlife Sanctu-
ary, where it is locally common at higher altitudes. The
relative inaccessibility of these higher altitudes (there
are few roads in the wildlife sanctuary, and none go
higher than 400 m altitude) may assist in the species’
protection. Therefore as no significant threat is
known, using the IUCN criteria (2001) I assess this
plant as Vulnerable (VU D2).
ETYMOLOGY.The specific epithet refers to the colour
of the flowers and plant.
NOTES.The spathaceous calyx and growth habit clearly
places this species in Aeginetia, and within that genus it
appears most morphologically similar to A. indica,
which is, as remarked above, morphologically variable.
However, A. flava differs from all known A. indica in
the possession of relatively conspicuous scale leaves
near the base of the flowering stem, its occasionally
branching habit, and most obviously in its bright
yellow corolla with broadly spreading, dentate corolla
lobes (those of A. indica are usually only slightly
spreading or not spreading at all and are not dentate);
it also has a somewhat smaller capsule and seeds
whose surface reticulations are smaller (c. 45 μmin
diam. in A. flava as opposed to c. 70 μminA. indica)
(Fig. 3). The seeds are clearly of the so-called ‘deeply
reticulate type’common in the Orobanchaceae of
Musselman & Mann (1976), having a testa with an
outer layer of enlarged polygonal cells whose outer
walls break down as the seed matures leaving a series
of walls enclosing pits of distinct size. The outer walls
of the testa were exceptionally fragile after prepara-
tion for SEM, thus some rupturing occurred during
normal specimen handling. Although yellow flowered
species occur in certain genera of the Orobanchaceae
e.g. (Cistanche and Conopholis) they were unknown in
Aeginetia until the discovery of this species. Extraction
of DNA for molecular analysis has so far proven
unsuccessful.
Acknowledgements
I would like to thank Bob Harwood whose love of
botany and exploration led to the discovery of this new
species and who collected material of it for me. I also
thank Clodagh Dooley who produced the SEM images of
the seeds of Aeginetia and Elaine Cullen for providing
the lovely illustrations.
References
Beck-Managetta, G. (1956). Orobanchaceae. In: A.
Engler, Pflanzenreich 4: 261. H. Buchna & Sohn,
Neudruck. (Photographic reprint of the original
volume issued in 1930).
IUCN (2001). IUCN Red List Categories and Criteria:
Ver s i o n 3. 1. IUCN Species Survival Commission.
IUCN, Gland, Switzerland & Cambridge, UK.
Musselman, L. J. & Mann, W. F. (1976). A survey of
surface characteristics of seeds of Scrophulariaceae
and Orobanchaceae using scanning electron mi-
croscopy. Phytomorphology 26: 370 –378.
Parnell, J. (2001). A revision of Orobanchaceae in
Thailand. Thai Forest Bull., Bot. 29: 72 –80.
____ (2008). Orobanchaceae. In: T. Santisuk, K.
Larsen, I. Nielsen, K. Chayamarit, C. Phengkhlai,
H. Pedersen, J. Parnell, D. Middleton, M. Newman,
D. A. Simpson, P. C. van Welzen, S. Hul & M. Kato,
Flora of Thailand 9 (2): 142 –147. The Forest
Herbarium, National Park, Wildlife and Conservation
Department, Bangkok.
84 KEW BULLETIN VOL. 67(1)
© The Board of Trustees of the Royal Botanic Gardens, Kew, 2012
