Eugenia sapoensis Jongkind from Liberia and Eugenia breteleri Jongkind from Gabon, two new forest species (Myrtales: Myrtaceae)

Two new forest species, Eugenia sapoensis sp. nov. and Eugenia breteleri sp. nov., from Liberia and Gabon respectively, are described and illustrated here. Both are shrubs with comparatively large red fruits. They resemble each other, but E. breteleri differs from E. sapoensis in having twigs with conspicuously peeling bark, 6–8 pairs of main lateral nerves, versus 4–6 pairs, and fruits with a peduncle of 3–5 mm rather than 1– 2 mm long. Eugenia breteleri grows up to 3 m high while E. sapoensis does not grow higher than 1.4 m.


Introduction
Eugenia is a genus of about 1000 species (WCSP 2014) but it is with ca.60 species not very species rich in Africa (van der Merwe et al. 2005), and even less so in the forests of the Guineo-Congolian Region (sensu White 1979).Including the new species, there are ten Eugenia species currently recognized for Liberia and the same number for Gabon.Only one species, Eugenia gabonensis Amshoff, is known from both countries.
The Myrtaceae flora publications for different parts of the Guineo-Congolian Region, like the Flore du Gabon, are at least 46 years old.Herbaria house large collections of Eugenia specimens from this Region that can not be identified to species with the existing floras.Furthermore, there are many unresolved taxonomic and nomenclatural issues within the genus (Verdcourt 1999).These facts show that new studies of Eugenia of the Guineo-Congolian Region are urgently needed.Preparing the still missing Myrtaceae part of the Flore du Cameroun could be a good start.Recently, several phylogenetic studies on Eugenia have been published (e.g.van der Merwe et al. 2005, Mazine et al. 2014) to clarify the relationship between the clades, regrettably they did not include any of the species that occur in forests of Central and West Africa in their research.
During recent fieldwork a small Eugenia shrub with large pinkish red fruits was collected in the forest near the Sapo National Park in Liberia.It is named here Eugenia sapoensis sp.nov.Most Eugenia species in this region have smaller fruits that are often very dark reddish or dark purplish at maturity as in the case of Eugenia calophylloides DC. (Fig. 1).Most species are larger too, up to medium-sized understory trees, and are flowering and fruiting much more profusely.The new species could not be keyed out with the Flora of West tropical Africa (Heine 1963) or with the Flore du Gabon (Amshoff 1966).The closest other species from the Guinea-Congolian Region seems to be E. kameruniana Engl.from Cameroon.This species is also a small forest shrub with large bright red fruits, but has leaves about 1.5-2 times the size of those of the new species and a narrow cordate, not attenuate, leafbase.No comparable Eugenia species is known from Liberia and neighbouring countries.Searching through the herbaria a Eugenia shrub from the forest of south-western Gabon with comparable fruits and general leaf shape was found.This shrub still differs from E. sapoensis sp.nov. in having more main lateral nerves and twigs with conspicuously peeling bark.It is also larger than its Liberian relative and the peduncle of the fruit is longer.It is named here E. breteleri sp.nov.The flowers of this new species are not yet known, but the calyx lobes still present on the fruits suggest that the flowers are likely to be small like in E. sapoensis sp.nov.
Considering the large geographical gap and the differences observed between the two new species, it is more likely that they are the result of parallel evolution and not necessarily closely related.Most Eugenia species in the tropical African forest seem to be restricted to a relatively small area.
In several publications the taxonomical importance of the seed and embryo of African Eugenia species was shown (van Wyk 1980, van Wyk & Botha 1984).No differences could be found on this point between our new species.Both new species, and Eugenia kameruniana Engl., should, based on their seed and embryo, be placed in Eugenia "Group X" as described by Van Wyk & Botha.This supports the statement that this group has a wide distribution in sub-Saharan Africa (van der Merwe et al. 2005) All material cited here for the two new species was collected after the floras for these countries were published.

Materials and Methods
Normal practices of herbarium taxonomy have been applied to study the available herbarium material from BR, K, P, and WAG.E. sapoensis sp.nov.has recently been studied in the field on several occasions.Preliminary assessments of the IUCN Red List categories of threat were performed using the IUCN criteria and the RBG Kew website http://geocat.kew.org.

Results
Eugenia shrubs from the forests of Liberia and Gabon, that could not be identified with the existing floras, are described as two new species endemic to Liberia and Gabon, respectively.They can be easily separated from the already known species from these countries by their relatively big red fruits and small leaves (Table 1  main lateral nerves meeting in a conspicuous sub-marginal nerve, looping 2.5-6 mm from the margin, midrib impressed above.Inflorescences strongly reduced, axilar and terminal, with 1 or 2 flowers, bracts tiny, early caducous.Flowers inconspicuous, glabrous, green and whitish; peduncle ca. 1 mm long, green; calyx lobes and petals ca. 2 × 2 mm, both 4 in number; stamens ca.20, 1-1.5 mm long; anthers ca.0.5 mm long; style not seen.Fruit single or with two together, subglobose, 1.2-2 cm in diameter, glabrous, green to bright pinkish red, surface dotted with many secretory cavities, 1-or (rarely) 2-seeded; pulp sweet, whitish; seed subglobose to kidney-shaped, very pale, with a slight dip in the surface near the hilum, testa smooth and thin but very strong; cotyledon kidney-shaped, fused for the larger part, covered with many secretory cavities; peduncle 1-2 mm long; calyx lobes ca. 2 mm long and wide, rounded, glabrous, not or hardly larger than in flower but more coriaceous.Seedling with the first 3-4 pairs of leaves only a few mm long.

Distribution and habitat
Undergrowth of evergreen lowland forest; 40-165 m altitude.Only known from the Sino River basin in Liberia.

Conservation status
The "Extent of Occurrence" (EOO) is 1,858 km 2 and the "Area of Occupancy" (AOO) is 32 km 2 , both count as "Endangered".Only one of the specimens was collected in the National Park.I have walked long distances within the EOO area often without finding one single plant of this species, it is really not common.Considering all the economical development planned in this part of Liberia, "Endangered" is the appropriate status.

Comment
The 2 tiny mature flowers collected seem to be lacking a style and could be male flowers, but they are too few to ascertain whether this is not caused by insects or other damage.

Diagnosis
A shrublet related to E. sapoensis Jongkind, but larger, twigs with conspicuously peeling bark, leaves with 6-8 pairs of main lateral nerves and fruits with a longer (3-5 mm) peduncle.

Etymology
Named after F.J. Breteler who was responsible for the organisation of the two expeditions that led to the discovery of the new species.

Description
Shrublet 1.3-3 meter high, glabrous.Twigs with bark conspicuously peeling in thin strips.Leaves opposite or tri-verticillate, entire, petiolate; petiole 1.5-5 mm long; lamina papery, drying slightly reddish, glabrous, 5.5-10 cm long and 2-4.5 cm wide, apex long acuminate, base attenuate, with 6-8 pairs of main lateral nerves with several smaller, parallel ones in between, meeting in a conspicuous submarginal nerve up to 4 mm from the margin, midrib impressed above.Inflorescences strongly reduced, axillar or terminal, with up to five flower buds, bracts filamentous, ca.1.5 mm long, early caducous, immature flower buds almost glabrous with a few hairs on the edge of the calyx.Fruits single, glabrous, 10-25 mm in diameter, 1-seeded, surface with many secretory cavities; seed sub-globose; embryo kidney-shaped, cotyledons fused for the larger part, covered with many secretory cavities; peduncle 3-5 mm long; 4 calyx lobes 1-1.5 mm long, longer than wide, rounded, glabrous.

Distribution and habitat
Undergrowth of evergreen lowland forest in the Rabi-Kounga area in south-west Gabon.

Note
On the label of Breteler 10319 the flowers are described as white when open, but on the specimens only small flower buds are found.

Conservation status
Based on the only 3 specimens the "Extent of Occurrence" (EOO) is 95 km 2 and the "Area of Occupancy" (AOO) is 12 km 2 , the first counts as "Critically endangered" (CR) and the second as "Endangered" (EN).I expect that in this case the limited number of specimens might for a large part show the lack of botanical exploration in this, still densely forested, part of Gabon.For the moment "Vulnerable" (VU) could be more appropriate.

Discussion
Eugenia sapoensis sp.nov.and E. breteleri sp.nov.can be easily separated from all other earlier described species from the forest area where they are found.With the large geographical gap between the two new species, it is more likely that they are the result of parallel evolution and not necessarily closely related.Most Eugenia species in the tropical African forest seem to be restricted to a relatively small area.
There are still more undescribed Eugenia species in these forests, and also already in herbaria, but these are closer to earlier described species and more difficult to delimitate.A problem is that a lot of the known species are still incompletely known, especially those from Cameroon.For some species the fruits, and for others the flowers have not yet been collected.Due to this lack of material, it is momentarily impossible to create a practical key to the Guineo-Congolian Eugenia species.This key can only been prepared after the older Eugenia names available for this floristic Region have found their place as synonyms or as more clearly delimited species.

Fig. 2 .
Fig. 2. A-C.Eugenia sapoensis sp.nov. A. Branchlet with fruit.B. Cross section of the fruit and single large seed.C. Lateral view of embryo (r = radicular protuberance).D-E.Morphology of the seed of Eugenia "Group X" as described by van Wyk (1980).D. Seed with part of the thin testa removed showing the surface of the embryo beneath (h = hilum).E. Lateral view of embryo (r = radicular protuberance).A-C from Jongkind 9351; D & E from van Wyk & Botha (1984: 66).Photographed by the author.

Fig. 4 .
Fig. 4. Eugenia breteleri sp.nov. A. Branch with leaves.B. Detail of leaf from below showing secretory cavities.C. Fruit (from pickled specimen) with style and part of the calyx still present.D. Cross section of fruit and single seed.A & B from Breteler 11457, C & D from Breteler 11546.Drawing by Hans de Vries.
EtymologyThis species is named after the Sapo National Park, the oldest national park in Liberia.DescriptionBranching shrublet about 0.8-1.4meter high.Twigs smooth, glabrous, brown, often shiny.Leaves opposite, entire, glabrous, petiolate; petiole < 3 mm long; lamina papery, with many translucent secretory cavities, 7-12 cm long and 2.3-5.5 cm wide, apex long acuminate, base attenuate, 4-6 pairs of It is still too early to tell if this species shows the cryptic dioecity seen in many other African species in Eugenia (van der Merve et al. 2005: 22).