Pichonia munzingeri (Sapotaceae), a new and rare micro-endemic species from New Caledonia
Author
Gâteblé, Gildas
Institut Agronomique néo-Calédonien (IAC), Equipe ARBOREAL, BP 711, 98810 Mont-Dore, Nouvelle-Calédonie.
gateble@iac.nc
Author
Swenson, Ulf
Department of Botany, Swedish Museum of Natural History, PO Box 50007, SE- 104 05 Stockholm, Sweden.
text
Candollea
2019
2019-03-28
74
1
1
7
journal article
25578
10.15553/c2019v741a1
ac6c9e7c-6e97-47f5-a163-e21ab8c840b8
2235-3658
3404492
Pichonia munzingeri
Gâteblé & Swenson
,
spec. nova
(
Fig. 1B
,
2–3
).
Pichonia munzingeri Gâteblé & Swenson
is similar to but differs from
P. daenikeri (Aubrév.) Swenson et al.
in being a much smaller shrub having small, up to
5 cm
long, oblong, almost glabrous leaves; petioles being canaliculate and less than
10 mm
long.
Fig. 1. –
Pichonia munzingeri
Gâteblé & Swenson.
A.
Overview
of the Montagne des Sources fire on 29 December 2005, the arrow points to the fire in the Oumbéa creek;
B.
Upper population in degraded maquis vegetation showing
Pteridium esculentum
(G. Forst.) Cockayne
flammable dead whitish fronds along the pipe to the water catchment, arrows point to ten individuals of
Pichonia munzingeri
.
[Photos: G. Gâteblé]
Holotypus
:
NEW CALEDONIA
.
Prov. Sud
:
Mont-Dore
,
La Coulée
,
Captage de la Oumbéa
,
21°11'19"S
166°34’ 22"E
,
150 m
,
14.III.2018
, fl.,
Gâteblé
&
Rochard
1011
(
P
[
P001156237
]!
;
iso-
:
G
[
G00341841
]!,
MO
!,
MPU
!,
NOU
[
NOU089084
]!,
S
[
S18-39759
]!)
.
Shrub
up to
3–4 m
tall, usually erect but sometimes decumbent and even with erect and decumbent branches on the same plant.
Branches
tomentulose when young, ferruginous, soon glabrous.
Leaves
simple, alternate (a few sometimes subopposite), usually oblong but sometimes broadly elliptic to obovate, blade 3.0–5.0 (–7.0) × 1.5–2.5 (–3.0) cm, coriaceous, somewhat conduplicate in its entire length, slightly revolute; young leaves tomentulose, quickly glabrescent on both surfaces, with some scattered, usually short, appressed trichomes remaining below, especially along the midvein, but all eventually vanish; leaf base round; leaf apex obtuse or sometimes retuse; leaf venation brochidodromous with weak submarginal loops, midvein impressed above, prominent below; secondary venation of 8–12 pairs, weak; tertiary venation laxly reticulate, faint; higher venation areolate (high magnification); petiole 5–7(–10) mm long, ferruginously tomentulose, usually glabrescent and canaliculate.
Flower
5-merous, bisexual, usually axillary and solitary, rarely in fascicle of two, sessile or subsessile, subtended by a minute bract.
Sepals
ovate,
2–3 mm
long, base c.
1.5 mm
wide, the outers tomentulose on the entire outer surface, the inners with tomentum in the central part, flanked with glabrous surfaces and fimbriate margins, all being glabrous inside.
Corolla
campanulate, yellowish or greenish with paler lobe margins,
4–5 mm
long, glabrous; corolla lobes suborbicular or quadrangular in shape, of about the same length as the corolla tube.
Stamens
inserted in the tube orifice, shorter than the corolla lobes; anthers c.
1 mm
long.
Staminodes
inserted in the corolla sinus, oblong to lanceolate, entire.
Gynoecium
flask-shaped, c.
5 mm
long in total; ovary c.
2 mm
long, pubescent; style 2.5–3.0 mm long, glabrous, slightly exserted, simple, without visible stigmatic areas.
Fruit
1-seeded, ellipsoid, 28 ×
14 mm
, crowned with 3-mm-long remnant style; seed ellipsoid with a scar 25% of circumference and 100% of the seed length (observed from a single immature seed); cotyledons planoconvex without endosperm and radicle.
Etymology
. – This new species is named in honor of our colleague and friend Jérôme Munzinger who has revised, along with numerous authors, many taxa in
New Caledonia
. Jérôme used the
Centre
IRD in Nouméa for seven years as his base for numerous fieldworks in the archipelago. His eye for undescribed species has generated too many novelties for a single researcher to handle and that is why he built an extensive collaborator network across the world. In 2011 Jérôme returned to Montpellier (
France
) where he continues his excellent botanical studies. At the time of writing, he has described 69 endemic species for
New Caledonia
of which 46 are
Sapotaceae
.
Distribution and Ecology
. –
Pichonia munzingeri
is so far only known from the Oumbéa Creek, one of the tributaries of La Coulée River within the Mont-Dore municipality (
Fig. 4
). It grows in degraded maquis and rainforest remnants, on the lower and wettest parts of the slopes, though it is not a riparian species. It occurs on ultramafic substrate with peridotites rocks. It seems to flower and fruit mainly between March and June. So far, during seven visits between
2016 and 2018
, only one fruit has been observed. One possible explanation is habitat destruction and a decline of natural pollinators following the fire in 2005 (see conservation status below). We suspect that the species is protandrous with pollen release before the style becomes exserted and receptive to pollen in order to prevent self-pollination.
Conservation status
. – Even if only preliminary results are available,
Pichonia munzingeri
has a unique phylogenetic position, being the sister species to all congeners in
New Caledonia
and, hence, the oldest lineage of its kind in the territory. It has been found in only one location with two very small subpopulations on both sides of Oumbéa Creek separated by less than
600 m
.
The upper subpopulation has some 30 individuals whereas only three have been located in the lower one. In the upper subpopulation,
P. munzingeri
grows along a track to a water catchment area built in 1997 that was expanded in 2001. It is possible that some individuals were removed when the catchment area was established. Oumbéa Creek, Coulée River, and the Montagne des Sources protected area were severely damaged by a deliberately set fire at the end of the 2005 dry season that burned around
43 km
² (
Fig. 1A
). Both subpopulations of
P. munzingeri
must have been badly impacted by this anthropogenic fire because most plants are regrowth from burnt stumps and not juveniles. The lower subpopulation is adjacent to a popular water hole where people enjoy swimming during the hot season and where the vegetation (including the new
Pichonia
) is regularly cut down for setting up camp fires. After the 2005 Montagne des Sources severe fire, the ground has become infested by
Pteridium esculentum
(G. Forst.) Cockayne
, a species that is highly flammable in the dry season and well known to facilitate the spread of new fires (
JAFFRÉ et al., 1998
). Hence, the main threat to
Pichonia munzingeri
is the frequent anthropogenic fires which are likely to further reduce the populations size. The calculated Area of occupancy (AOO) value is only
4 km
² (grid of 2 ×
2 km
) a value also applicable for Extent of Occurrence (EOO). All in all, effective
in situ
conservation appears very important to maintain high genetic diversity and we therefore suggest that
P. munzingeri
is assigned a preliminary status of “Critically Endangered” [CR B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v); C2a(i); D] based on the IUCN Red List Categories and Criteria (
IUCN, 2012
).
Notes
. –
Pichonia munzingeri
is particularly similar to
Pycnandra francii
in habit, from which it is distinguished by an areolate venation and the presence of staminodes (see above). The areolate venation is a feature present in all species of
Pichonia
and
Pleioluma
(Baill.) Baehni
, but
Pichonia
have stamens inserted in the tube orifice (not in the lower half of the corolla tube) and seeds with plano-convex cotyledons without endosperm (not foliaceous cotyledons with endosperm). Among the congeners,
P. daenikeri
is the most similar but
P. balansae
(Baehni) Swenson & Munzinger
is also to some extent similar. The foliage of
P. munzingeri
is much smaller (usually less than
5 cm
long) and somewhat conduplicate with canaliculate, shorter petioles (usually no more than
7 mm
long) than those of
P. daenikeri
and
P. balansae
.
The foliage together with sessile (or subsessile) flowers make
P. munzingeri
a species easy to identify in the field.
Paratypi
.
–
NEW CALEDONIA
.
Prov. Sud
:
Mont-Dore
,
La Coulée
,
Captage de la Oumbéa
,
21°11'19"S
166°34'22"E
,
150 m
,
8.V.2017
, fl.,
Gâteblé
936
(
MPU
,
NOU
, P, S)
;
ibid. loco
,
8.V.2017
, fl.,
Gâteblé
937
(
NOU
, P, S)
;
ibid. loco
,
14.III.2018
, fl.,
Gâteblé
&
Rochard
1012
(P)
;
ibid. loco
,
14.III.2018
, fl.,
Gâteblé
&
Rochard
1013
(
NOU
)
;
ibid. loco
,
14.III.2018
, fl.,
Gâteblé
&
Rochard
1014
(S)
;
ibid. loc
.,
21.V.2018
, fr.,
Gâteblé
1026
(
NOU
, P)
.