Species Action Plan-Trilepisium gymnandrum

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Species Action Plan – Trilepisium gymnandrum
By François Baguette, Bruno Senterre, Teesha Baboorun, Said Harryba, Emily Beech

Species description
Based on the description provided by Friedmann (1994) and our own observations made on sterile
trees in situ, Trilepisium gymnandrum is a deciduous tree to 25 m high, developing a typically fluted
and twisted base and to 60 cm in diameter. The bark light brown with lenticels in irregular lines, and
with a white sap rapidly changing colour to light brown (milk coffee). Dense-crowned and drooping
branchlets. Leaves are simple, alternate, elliptic, glossy to 15 cm long with elongated, dripping tips.
Old leaves are shorter and more rounded than young ones. Leaf blades dark green on the upperside,
paler on the underside, with distinct midribs and petioles to 1.5 cm long. Inflorescences axillary,
normally solitary, discoid, each to 1 cm wide, with many male flowers (reduced to 3 mm long stamens)
and one central female flower. The fruit, even though never seen ripe in Seychelles, is an oblong drupe
to 1.5 cm long, possibly dark-red when ripe and with the single seed immersed in a fleshy receptacle
(Hansen & Laboudallon 2013; Gerlach 2000).
The flowering season is thought to be from September to October.
The species is potentially dispersed by birds, reptiles and fruit bats. However, the high abundance of
seedlings directly in the vicinity to adult trees decreasing rapidly with the distance suggests that the
species is not spread across long distances. The species specificity to submontane ravine forests also
reduces its capacity to spread in large areas.
Conservation status
This species has been assessed as Critically Endangered under Criterion D as there are only five known
mature individuals based on recent research by the authors of this study.
Link to IUCN assessment when available online
Distribution
This species is currently found only on Silhouette Island and is endemic to Seychelles. According to
notes on the specimen Horne 417 (at Royal Botanic Gardens, Kew herbarium), this species was found
on “all Seychelles islands” in 1874 but was not common. This species was then recorded by Thomasset
in the early 20th Century on Mahé, without a locality mentioned but we expect that the species could
have existed in the area of Cascade and Mare aux Cochons (Robertson 1989). Recent explorations
have not rediscovered the species on Mahé.
On Silhouette, Friedmann (1994) rediscovered a few trees of Trilepisium in two localities (SW of Grand
Congoman at ±300m alt. and in between Mare aux Cochons and Mont Dauban at ±500m alt.) but
without exact coordinates and the trees have never again been seen. Additionally, Friedmann (1990)
saw another adult tree on the Grand Barbe trail, above Glacis Noel. In a KBA study (Senterre et al.
2013) only juvenile plants of less than 3 m tall were seen.
In this study, Dr. Bruno Senterre, in collaboration with the Island Conservation Society (ICS),
rediscovered five adult trees on Silhouette Island with many juveniles. One adult Trilepisium was found
in the Anse Mondon valley (“Dans Mapou”), two at Rivière machabée, and two at Rende d’Avance (a
newly discovered population).
Overall, the species is restricted to an area less than 16 km2. The total extent of occurrence of the
species is 3.383 km2.
Habitat
The habitat-type where Trilepisium is found appears to be “Submontane ravine forests” (Senterre &
Wagner 2014). This habitat-type is rare, has been intensely deforested in the past, and is at the same

time under-explored due to its difficult accessibility. Additionally, most explorers have focussed
primarily on the hottest spots of endemism, i.e. in the montane belt. Trilepisium has probably never
been a very abundant species, considering its narrow ecological range.
Figure 1 Distribution map of Trilepisium gymnandrum. The background map represents the different types of habitats (see
Senterre & Wagner 2014).
Populations
The species is found in six known subpopulations on Silhouette Island. In total, only five mature
individuals are known, with exact GPS coordinates, and spread in three subpopulations (namely Anse
Mondon valley, Rivière Machabée and Rende d’Avance (discovered by the authors of this report in
2017-18). There are fewer than 200 known juvenile individuals across the six subpopulations.
The table below, extracted from Senterre et al. (2018), summarizes the data on the six
subpopulations from Silhouette Island and the extinct one from Mahé.
N°
Population
First seen
Last
seen
Max.
abundance
Current
abundance
Adults-
sterile
Adults-
repro.
Juveniles
1
Mare aux
Cochons
(S.. = Scott
Vale)
Friedmann
(1994)
2012
Unknown
Unknown
Unknown
Unknwon
Unknown
2
Rivière
Machabée
(S.)
Senterre
(2012)
2018
77
77
0
2
75
3
Vallée de
l’Anse
Mondon
Carlstrom
(1996)
2018
36
36
0
1
35

(=Dans
Mapou)
4
Mont Pot
à Eau-
Jardin
Marron
Senterre
(2012)
2018
8
8
0
0
8
5
Mont
Dauban
Senterre
(2009)
2018
40
40
0
0
40
6
Rende
d’Avance
This study
2018
6
6
0
2
4
7
Mahé
(Cascade?)
Thomasset
(1910?)
1910?
?
0
Table 1 Summary of the seven populations for Trilepisium gymnandrum.
Threats
There are no currently identified threats. The habitat has declined in the past due to deforestation of
the submontane habitat but this is not currently threatening the species.
Recovery actions
Past and Current Management Actions
93% of Silhouette Island, including all Trilepisium populations, has been declared National Park in
2010. The island is owned by the Seychelles Government that gave a lease to the Islands Development
Company (IDC) to manage it since 1983. In 2008, the Silhouette Foundation, regrouping all main
stakeholders from Silhouette Island (Ministry of Environment, Energy and Climate Change (MEECC),
Seychelles National Parks Authority (SNPA), Islands Development Company (IDC) and Island
Conservation Society (ICS), was created in order to conserve, rehabilitate & enhance Silhouette
ecosystems in harmony with sustainable low impact human development and eco-tourism. The
Silhouette National Park is managed under the Silhouette Foundation by the Island Conservation
Society, a non-governmental organization, in collaboration with SNPA and MEECC. However, an
official Regulation Order is lacking to define clear rules and regulations within the boundaries of the
National Park.
There is no known ex situ collection of Trilepisium gymnandrum and no conservation activities
focusing on Trilepisium gymnandrum have ever been done in the past.
Recovery aims
 Increasing the number of mature individuals contributing to a viable population, allowing the
status of the species to be downgraded.
 A genetic representative ex situ collection base.
 A viable population of this species on Mahé Island.

Suggested conservation actions
The conservation actions in the table have been ranked by priority.
Activity
Budget
needed to
achieve this
(per year)
Timeframe
More details
Mature individuals should be
monitored to identify fruiting
periods.
4000 USD
Monthly, on a long-term basis
3 days for 2 staff on a monthly basis: 3*2*12=72 days per year.
Salary based on one Conservation Officer plus one Ranger wages.
All adult trees to be monitored
Representative ex situ
collections of Trilepisium
gymnandrum should be made,
encompassing the remaining
genetic diversity of the
species.
700 USD for
collection of
ripe fruit and
seedling.
Nursery
construction:
25 000 USD
(once)
Nursery
maintenance:
1000 USD
Twice a year during fruiting season.
6 days for 2 staff per year: 6*2=12 days per year.
Seed collection from all known adult trees. Limited number of
seedlings to be harvested due to Critical status. Guidelines
available on: http://globaltrees.org/wp-
content/uploads/2013/11/tree_species_low.pdf
Propagation protocols should
be developed to allow this
species to be propagated in
various locations.
1750 USD
Once
7 days. Consultancy fee: 250$/d
As the species is now
considered extinct on Mahé
but was previously known to
occur there (possibly at
Cascade), this species should
2 500 USD for
6 working
days for 15
staffs.
Seedling should be planted during NW
monsoon from November to March. Ravine
forests around Jardin Marron would good
restoration sites.
 The amount of working days would depend on the amount of
seedlings available and man power.
 Ideally, 100 seedlings should be planted once a month from
November to March. A team of 15 persons carrying up to 8
seeding would be necessary.

be considered a candidate for
reintroduction into the
submontane habitat on
Silhouette Island and Mahé.
Additional
boat fare:
1500 USD
50 000 USD
for
reintroduction
on Mahé
For reintroduction on Mahé, seedlings can be
produced on Silhouette Island and shipped to
Mahé for restoration. Ravine forests at
Cascade and Mare aux Cochons would be
good restoration sites
 Seedlings 30cm high in 7x7cm potting pots. Sites should also
be carefully selected and relatively easy to access.
 If labourers from Mahé are to be employed, additional costs
are needed for boat transfers.
 The budget assumes that a nursery is already available
 For reintroduction on Mahé the budget needs to include
production costs on Silhouette, biosecurity costs, transport
costs from Silhouette to Mahé, transport costs on Mahé and
restoration costs on Mahé.
Reinforcement
N/A
N/A
At current sites is not necessary as the plant is regenerating well.

Conclusion
Trilepisium gymnandrum has been assessed as Critically Endangered under the IUCN Criterion D as
there are only five known mature individuals. All individuals are restricted to a single island in
Seychelles, Silhouette, and its distribution range is less than 16 km2. Therefore, the specific activities
highlighted above are essential for the preservation of the species. Additionally, we recommend that
more surveys should be done in the Silhouette National Park in order to reassess the status of the
population at Mare aux Cochons and find additional mature trees on the island. Due to the fact that
recognizing adult Trilepisium trees is very challenging, its trunk being roughly similar to any other of
the most common tree species in its habitat, it is more than likely that more trees will be found if more
exploration is being done.
Due to the critical status of the species, we recommend that any conservation activities suggested
above are undertaken in collaboration with the Ministry of Environment, Energy and Climate change
(MEECC) in Seychelles, the Seychelles National Parks Authority (SNPA), the Island Conservation Society
(ICS) and international organizations such as Botanic Gardens Conservation International for their
expertise. We also recommend that local experts and organization as the Seychelles National
Herbarium and the Terrestrial Restoration Action Society of Seychelles (TRASS) are involved in the
project.
Propagating the species on Silhouette Island and Mahé will require the close collaboration with private
stakeholders working on Silhouette Island. For such project to be successful, additional awareness will
be needed in order to get the logistical and financial support of all organization. The Silhouette
Foundation having a limited budget allowing only basic conservation work on Silhouette, additional
funding will need to be sourced. International botanical garden could be approached in order to
develop long-term support and collaboration.
References
Friedmann, F. (1990) Fleurs et arbres des Seychelles. Département des finances des Seychelles.
Friedmann, F. (1994) Flore des Seychelles. Dicotylédones. Institut français de recherche scientifique
pour le développement en coopération.
Gerlach, J. (2000) Trilepisium in Seychelles (Moraceae). Phelsuma 8: 50-54.
Hansen S.G. and Laboudallon, V. F. (2013) Flora of the Seychelles a field guide to selected plants.
Robertson, S.A. (1989) Flowering plants of Seychelles, Royal Botanic Garden, Kew.
Senterre, B. and Wagner, M. (2014) Mapping Seychelles habitat-types on Mahé, Praslin, Silhouette,
La Digue and Curieuse. Consultancy Report, Government of Seychelles, United Nations Development
Programme, Victoria, Seychelles, 124 pp.
Senterre B., Baguette F. and Chong-Seng, L. (2018) Silhouette Adaptive Conservation Management
Plan 2018-2022 using Bioma: a simple MS Access database.
Senterre, B., Baguette, F., Baboorun, T., Harryba, S. and Beech E. (2018) Population assessment for
three critically endangered species endemic to Seychelles: Impatiens gordonii, Psychotria silhouettae
and Trilepisium gymnandrum. Island Conservation Society, Botanic Gardens Conservation
International, Victoria, Seychelles, 26pp.