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\begin{document}

\title{Aspidistra pentagona (Asparagaceae, Convallarioideae), new species from
northern Vietnam}



\author[1]{Leonid Averyanov}%
\author[2]{Khang Nguyen}%
\author[3]{Hans-Juergen Tillich}%
\author[1]{Tatiana Maisak}%
\author[4]{Valeria Shvanova}%
\affil[1]{Komarov Botanical Institute}%
\affil[2]{Inst. of Ecology and Biological Resources}%
\affil[3]{Ludwig-Maximilians-University}%
\affil[4]{Komarov Botanical Inst. of the Russian Academy of Science, St Petersburg, Russia}%


\vspace{-1em}



  
  \date{May 25, 2024}


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\selectlanguage{english}
\begin{abstract}
This paper continues the publication of Aspidistra species newly
discovered in the flora of Vietnam. It includes an illustrated
description of A. pentagona, found in northern parts of the country.
Detailed analytical color illustrations, data on morphology and ecology,
phenology, tentative relationships, distribution, and expected
conservation status are provided for the discovered species.%
\end{abstract}%



\sloppy


\emph{Version of 2023 05 08}

NJB formatted

\textbf{Research}

\emph{Aspidistra pentagona} \textbf{(Asparagaceae, Convallarioideae),
new species from northern Vietnam}

\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}..

This paper continues the publication of \emph{Aspidistra} species newly
discovered in the flora of Vietnam. It includes an illustrated
description of \emph{A. pentagona} , found in northern parts of the
country. Detailed analytical color illustrations, data on morphology and
ecology, phenology, tentative relationships, distribution, and expected
conservation status are provided for the discovered species.

Keywords: Flora of Indochina, new taxa, plant diversity, plant taxonomy

\textbf{Introduction}

The genus \emph{Aspidistra} Ker-Gawler (1822, p. 628) is widely
distributed in mainland tropical and subtropical Southeast Asia. This
genus of flowering plants has been one of the fastest-increasing in
terms of species number over the previous two decades. The recent
comprehensive fundamental treatment of the genus (Tillich 2023) listed
209 species with a number of subspecies and varieties. Nonetheless, the
global inventory of this group appears to be far from complete. Here we
continue the publication of one more new species of the genus discovered
in northern Vietnam, in addition to many more species of this genus
already discovered in this area (Tillich 2023). Observations and
measurements of morphological features were made on living cultivated
plants grown from seedlings collected in nature. Detailed analytical
photos of plant parts compiled into a plate were made from living plants
prior to the preparation of the type herbarium specimens. The formal,
illustrated descriptions of the new species are presented below. The
type image and all photos are available in the database of the Herbarium
of Komarov Botanical Institute of the Russian Academy of Sciences,
``Herbarium LE'' (\emph{https://en.herbariumle.ru/}), for free access.

Aspidistra pentagona \ldots{}\ldots{}\ldots{}\ldots{}\ldots{}.. ,
\emph{sp. nov.}\textbf{(Fig. 1)}

Diagnosis

The new species differs from the most closely related \emph{Aspidistra
superba} and all its relatives in having a pentagonal callus on the
stigma and very large petaloid ventral appendages of the perigone lobes,
forming a dome almost completely hiding the stigma.

\textbf{Type:} Vietnam, herbarium specimen prepared from cultivated
plant on 19 April 2023 by \emph{L. Averyanov VR161} (holotype: LE1170563
https://en.herbariumle.ru/?t=occ\&id=170373; photos of fresh plant parts
used for the type specimen preparation
LE01124126\emph{https://en.herbariumle.ru/?t=occ\&id=169838}) originally
collected in Ha Giang Province, Quan Ba District, Bat Dai Son Nature
Reserve, Can Ty Commune, Dau Cau 1 Village, around point 23\selectlanguage{ngerman}º05\selectlanguage{english}'26.3"\selectlanguage{english}N
105\selectlanguage{ngerman}º01\selectlanguage{english}'03.0"\selectlanguage{english}E, 1100--1150 m a.s.l., karstic, highly eroded mountains
composed of solid marble-like limestone, primary evergreen broad-leaved
humid forest on steep rocky slopes near mountain tops, terrestrial
rhizomatous herb in shady place, rare, 14 April 2018,\emph{L. Averyanov,
Nguyen Sinh Khang, Chuong Quang Ngan, T. Maisak, VR 161} .

\textbf{Paratype:} Vietnam, Ha Giang Province, Quan Ba District, Bat Dai
Son Nature Reserve, Can Ty Commune, Dau Cau 1 Village, around point
23\selectlanguage{ngerman}º05\selectlanguage{english}'26.3"\selectlanguage{english}N 105\selectlanguage{ngerman}º01\selectlanguage{english}'03.0"\selectlanguage{english}E, 1100--1150 m a.s.l., karstic, highly eroded
mountains composed of solid marble-like limestone, primary evergreen
broad-leaved humid forest on steep rocky slopes near mountain tops,
terrestrial rhizomatous herb in shady place, rare, 14 April
2018,\emph{L. Averyanov, Nguyen Sinh Khang, Chuong Quang Ngan, T.
Maisak, VR 161} , sterile plant (LE01054091
https://en.herbariumle.ru/?t=occ\&id=4418).

Etymology

The species name refers to the prominent pentagonal callus on the stigma
disc.

Description

\textbf{Herb} terrestrial, perennial, rhizomatous, (40)60--90 cm
tall.\textbf{Rhizome} terete, epigeous to hypogeous, creeping,
plagiotropic, (12)14--20(24) cm long, (8)10--12(14) mm in diameter,
simple or few branched; densely nodal, almost naked, with (4)5--6(7)
distant erect leaves; each annual sympodium 1-leaved, with few thick,
dull yellowish roots. \textbf{Cataphylls} 3--4(5), convolute, tubular,
herbaceous, dark dirty violet, to dark reddish brown, (4)5--8(10) cm
long, early disintegrating, withered, and completely disintegrating
before anthesis.\textbf{Leaves} petiolate; petiole grassy green, rather
rigid, erect, straight, (25)30--55(65) cm long, 5--6 mm wide, distinctly
inflated at the base to 7--8 mm in diameter (when fresh), channeled
adaxially, naked; leaf blade upright, arcuate, or almost horizontal,
ovate to broadly elliptic, almost round at the base, acuminate to
shortly attenuate at the apex, (15)20--30(35) cm long, (8)10--14(16) cm
wide, uniformly dark glossy green, with prominent midvein on the lower
surface and many conspicuous secondary veins at both sides.
\textbf{Flowers}solitary, pedunculate, not widely opening, ovoid to
broadly ovoid in outline, 2.2--2.6 cm long, 1.6--1.8 cm wide, placed
perpendicularly to the ground. \textbf{Peduncle} white, speckled with
reddish brown, 2.5--3.5 cm long, 2--3 mm in diameter, horizontally
directed, distally ascending, with 6--7 bracts, entire or sometime
splitting at the apex; 1--2 bracts placed at the base and 1 bract at the
middle of the peduncle are small, tubular, papyraceous to scarious,
whitish or purplish, sparsely speckled with purple, 5--8 mm long and
wide (being flattened); 4(5) bracts placed at the apex of the peduncle,
densely adpressed to the flower base, they are light green, heavily
marked with purple brown, ovate to broadly ovate, 1--1.4 cm long,
(1)1.2--1.8(2) cm wide (being flattened), concave, blunt or roundish at
the apex. \textbf{Perigone tube} (except perigone lobes) broadly
urceolate, (1)1.1--1.2(1.3) cm long, 1.6--1.8 cm in diameter, with 10
lobes; outside smooth, light greenish, heavily mottled with red brown;
inside smooth, glossy, dark purple violet to almost black, obscurely
20-ridged. \textbf{Perigone lobes} subsimilar, erect, narrowly
triangular, attenuate, and blunt at the apex, fleshy, with narrow thin
scarious margins, 14--16 mm long, 8--9 mm wide; outside smooth, reddish
brown; inside dirty brown to almost black, near the base, there is a
large, broadly oblong dull yellowish outgrowth (appendage) streaked with
reddish brown and slightly broadening at the apex; five large petaloid
appendages are 4.5--5.5 mm long, 3.5--4 mm wide and strongly down
curved, alternating with five smaller, more or less horizontally
spreading ones; outgrowths of all lobes overlap and form a dome above
stigma. \textbf{Stamens} 10; anthers sessile, broadly ovate to
hemispherical, (1.5)1.6--1.8(1.9) mm long and wide, adpressed to the
almost flat perigone tube base, with pollen sacs oriented upwards;
pollen bright yellow. \textbf{Pistil} mushroom-shaped, with peltate
stigma in the form of a massive, thick disc; ovary white, inconspicuous;
style white, cylindrical, very short, 1.2--1.4 mm tall, 4.5--5 mm in
diameter. \textbf{Stigma} large, fleshy, circular, (1.6)1.7--1.8(1.9) cm
in diameter; below white, dark purple violet to almost black near the
margin, distinctly 20-ribbed; the margin dark violet to almost black,
3--4 mm thick, with 20 prominent ribs; above white, more or less flat
with raised black margin and prominent, fleshy pentagonal callus,
heavily marked with dark purple; pentagonal callus starfish-shaped, 8--9
mm in diameter with 5 shortly triangular sagittate, conduplicate lobes
(1.8)2(2.2) mm long, (3.3)3.4--3.6(3.7) mm wide, emarginate at the apex,
from each apex are running to the margin two spreading, indistinctly
bifurcate whitish ribs with small purple elevations. \textbf{Fruits}
unknown.

Habitat and phenology

Perennial, terrestrial, rhizomatous herb. Primary broad-leaved humid
evergreen forests on highly eroded mountains composed of solid
marble-like limestone at elevations of 1100--1150 m a.s.l., commonly on
steep rocky slopes near mountain tops. Flowers in culture in April.

Distribution

Vietnam, Ha Giang Province (Quan Ba District, Bat Dai Son Nature
Reserve). Endemic.

Conservation status

Only a few immature plants of this very rare species were found in a
single location in the Bat Dai Son Mountains, which currently belong to
the Bat Dai Son Nature Reserve. According to available data, its area of
occupancy (AOO) is surely less than 10 km\textsuperscript{2}, with no
mature individuals observed. Taking into consideration the wide
deforestation in the area and the progressive decline of habitat
quality, the conservation status of this species may be preliminarily
assessed as Critically Endangered (CR B1a,b(iii,iv,v)+2a,b(iii,iv,v),
C2a, D) following the formal criteria proposed by IUCN (2022).

Similar species and notes

Our plant belongs to the group of species with petioles naked at the
base, a discoid stigma with a thick ribbed margin, and perigone lobes
bearing a ventral appendage hanging above the stigma. The most typical
species of this group are \emph{Aspidistra chunxiuensis} C. R. Lin \&
Yan Liu (2015: 163), \emph{A. daxinensis} M. F. Hou \& Yan Liu (2009:
371), \emph{A. guangxiensis} S. C. Tang \& Yan Liu (2003: 480), \emph{A.
latistyla} F. Y. Mo, C. R. Lin \& Yan Liu (2021: 73), \emph{A.
longipetala} S. Z. Huang (1986: 273), \emph{A. ovatifolia} Yan Liu \& C.
R. Lin in Lin, C. R. et al. (2014: 287), \emph{A. patentiloba} Y. Wan \&
Xiao H. Lu in Wan, Y. (1989: 99), and \emph{A. superba} Tillich (2005:
323). Among these species, our plant is easily recognizable for its
large, prominent pentagonal callus on the upper surface of the stigma
and the very large petaloid ventral appendages of the perigone lobes,
which form a dome almost completely hiding the stigma. The species
represents an integral element of primary limestone forests typical for
N Vietnam and SE China, as outlined in the modern plant geography of
Indochina as the South Chinese Floristic Province (Averyanov et al.
2003). In this regard, it can be expected to be found in Southeast
China.

\emph{Funding} --
\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}.

\textbf{Author contributions}

\textbf{\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}\ldots{}}

\textbf{Data availability statement}

Data available from the Herbarium LE Database
\textless{}\emph{https://en.herbariumle.ru/?t=occ\&id=4418}\textgreater{},
\textless{}\emph{https://en.herbariumle.ru/?t=occ\&id=170373}\textgreater{},
\textless{}\emph{https://en.herbariumle.ru/?t=occ\&id=169838}\textgreater{}

\textbf{References}

Averyanov, L. V. et al. 2003. Phytogeographic review of Vietnam and
adjacent areas of Eastern Indochina. -- Komarovia 3: 1--83.

Hou, M. F. et al. 2009. \emph{Aspidistra daxinensis} (Ruscaceae), a new
species from Guangxi, China. -- Bot. Stud. 50: 371--378.

Huang, S. Z. 1986. A new species of \emph{Aspidistra} from Guangxi. --
Guihaia 6: 273--274.

IUCN Standards and Petitions Subcommittee (2022) Guidelines for using
the IUCN Red List categories and criteria Ver. 14. Available
from:\emph{file:///C:/Users/Leonid\%20Averyanov/Downloads/RedListGuidelines.pdf}(accessed
08 May 2023)

Ker-Gawler, J. B. 1822. \emph{Aspidistra lurida. --} Bot. Reg. 8: 628.

Lin, C. R. et al. 2015. Two new species of
\emph{Aspidistra}(Asparagaceae) from Guangxi, China: \emph{A.
chunxiuensis} and \emph{A. longshengensis} . -- Phytotaxa 208: 163--169.

Lin, C. R. et al. 2014. \emph{Aspidistra ovatifolia} (Asparagaceae), a
new species from Guangxi, China. -- Novon 23: 287--290.

Mo, F. Y. et al. 2021. \emph{Aspidistra latistyla} (Asparagaceae), a new
species from China. -- Phytotaxa 512: 73--78.

Tang, S. and Liu, Y. 2003. \emph{Aspidistra
guangxiensis}(Convallariaceae), a new species from China. -- Novon 13:
480--482.

Tillich, H.-J. 2005. A key for \emph{Aspidistra} (Ruscaceae), including
fifteen new species from Vietnam. -- Feddes Repertorium 116: 313--338.

Tillich, H.-J. 2023. 200 years \emph{Aspidistra} (Asparagaceae), and now
more than 200 species: a new comprehensive determination key, and an
annotated bibliography of the genus. -- Nordic Journal of Botany 2023:
e03818: 1--34.

Wan, Y. 1989. Three new species of the genus \emph{Aspidistra} from
Guangxi. -- Bull. Bot. Res., Harbin 9: 97--102.

\emph{FIGURE}

\textbf{Figure 1.} Aspidistra pentagona sp. nov. (A) flowering plant,
(B) rhizome and base of petioles, (C) base of petiole, (D) flattened
leaves and flowers, (E) flowers, side view, (F) flattened scape bracts,
(G) intact flower, side view, (H) flower, frontal view, (I) flower, view
from below, (J) sagittal section of the flowers and intact pistil, (K)
sagittal section of the flower, pistil removed, (L) flattened perigone
lobes, (M) perigone lobe and section of perigone, adaxial surface and
side view, (N) base of perigone tube with stamens, view from above, (O)
half-base of perigone with stamens, side view, (P) stigma, view from
above, (Q) central callus of the stigma, (R) stigma, view from below,
(S) stigma, side view. All photos,
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