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Phytotaxa 405 (2): 083–090
https://www.mapress.com/j/pt/
Copyright © 2019 Magnolia Press Article PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
Accepted by Muthama Muasya: 19 May 2019; published: 31 May 2019
https://doi.org/10.11646/phytotaxa.405.2.3
83
Licensed under a Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0
Pycreus rubidomontanus (Cyperaceae), a widespread but undescribed species from
tropical West Africa
FILIP VERLOOVE1, JANE BROWNING2 & ATTILA MESTERHÁZY3
1 Botanic Garden Meise, Nieuwelaan 38, B-1860 Meise, Belgium. e-mail: filip.verloove@botanicgardenmeise.be
2 Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AE, United Kingdom.
e-mail: janebrowning@btinternet.com
3 Directorate of Hortobágy National Park, Sumen u. 2, H-4024 Debrecen, Hungary. e-mail: amesterhazy@gmail.com
Abstract
Pycreus rubidomontanus is described as a new species. It is relatively widespread in tropical West Africa where it had been
confused up to present with P. atrorubidus, a very rare endemic species from Zambia in south-central Africa that probably is
known only from the type gathering. Differences between these and other similar species are discussed and the new species
is copiously illustrated.
Keywords: Cyperaceae, new species, Pycreus, taxonomy, tropical West Africa
Introduction
Pycreus atrorubidus Nelmes (1952) was originally described based on a single collection (Milne-Redhead 4565, with
holotype in K). Although from Mwinilunga in Northern Rhodesia (current-day Zambia) in south-central Africa, it
was subsequently also reported from various parts of tropical West Africa. Hooper & Napper (1972) reported it from
Guinea, Sierra Leone, Ivory Coast and Liberia (see also Govaerts & Simpson 2007) where it was said to grow on
mountains up to 5,000 ft. It is particularly well-represented in the Nimba Mountain area (Adam 1983). As a matter of
fact, P. atrorubidus soon had a much wider distribution in tropical West Africa than it has in the area from where it
was described.
During the preparation of an account for Cyperaceae in tropical West Africa (Mesterházy & al., in prep.), we
found that collections of alleged Pycreus atrorubidus from that area did not conform with the plant formerly described
by Nelmes, not only on morphological but also on ecological and geographical grounds. In fact, this inconsistency
was already observed in the past by other cyperologists. J. Raynal, for instance, identified a Pycreus from Bambui,
Cameroon, preserved in P, as “Pycreus atrorubidus Nelmes (au sens de la FWTA)”, implicitly suggesting that this is
not exactly the same as was described by Nelmes.
The West African species is here described as a new species, Pycreus rubidomontanus. It mainly occurs in
mountains of tropical West Africa from Guinea to Cameroon.
Taxonomic part
Pycreus rubidomontanus J.Browning, sp. nov. (Fig. 1, 2, 3)
= P. atrorubidus sensu. auct. afr. occ., non Nelmes
Perennial, stoloniferous and rhizomatous in dense compact tussocks, rhizomes and stolons thin, ca. 0.5–1 mm across.
Culms many per tussock, erect, 8–25 cm long. Leaf blade filiform, 8.5–16 cm long × 0.3–1 mm wide. Inflorescence a
single sessile cluster of 3–16 spikelets (rarely a single spikelet). Involucral bract single (or with a second much smaller)
erect, leaflike, held as an extension of the culm and making the inflorescence appear pseudolateral, 4–8(–13) cm long.
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Spikelets 3–14 (–16) × 2(–2.5) mm, lanceolate, rachilla 0.4–0.5 mm wide, straight but visible as a zig-zag pattern
between the glumes when the glumes are still attached. Glumes not closely imbricate, 2–2.4 x 1.5–1.7 mm, deciduous,
strongly concave, dark reddish brown to almost black, ovate to elliptic, flanks veinless, with a narrow hyaline margin,
rounded with the dark green midrib not reaching the tip, infolding with age. Stamens 2, anthers pale yellow, 0.25–0.3
mm long. Stigma branches 2, in dorsiventral positions. Nutlet red-brown, laterally compressed, obovoid, apiculate,
1.0–1.1 × 0.8–0.9 mm, papillose, with obvious papillae in longitudinal rows.
TYPE: Guinea, Hollandé, Tossékré, Labé, 15.X.1956, J.-G. Adam 12732 (holotype: K K001322386; isotypes: BR
BR0000018180220, P P00584799).
FIGURE 1. Pycreus rubidomontanus. A: habit; B: spikelets; C: rachilla, glumes, nutlets and filaments; D: nutlet; E: floret (all from Adam
12732, K) (J. Browning)
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FIGURE 2. Pycreus rubidomontanus in habitat. Sierra Leone, Loma Mountains (Mount Bintumani), 2012. Photo Attila Mesterházy.
RECOGNITION AND AFFINITIES:
Pycreus rubidomontanus has hitherto been confused with P. atrorubidus in tropical West Africa. Although superficially
similar both are probably only remotely related. P. rubidomontanus is a clearly perennial species that ultimately forms
mats, producing both rhizomes and stolons (vs. annual). It has an erect involucral bract up to 13 cm in length (vs. bract
patent and much shorter, 1–3.5 cm long). Spikes tend to be more numerous and spikelets longer. Glumes have a clearly
hyaline apex and margins (in P. atrorubidus, in contrast, the apex of the glume is even darker than the remaining part).
Nutlets are finely papillose, with papillae in numerous longitudinal rows (Fig. 3; in P. atrorubidus few papillae are
seen but this may be due to the nutlets being immature in the type material). In Table 1, the main differences between
Pycreus rubidomontanus, P. atrorubidus and other similar-looking species are listed.
Although having been confused so far with Pycreus atrorubidus, the closest relatives of P. rubidomontanus may be
P. poikilostachys Nelmes, P. melas (Ridl.) C.B.Clarke, P. capillifolius (A.Rich.) C.B.Clarke and related species. These
species form a complex of probably closely related species that differ from each other in the smallest of details (see
also Reynders 2013). Apart from the rachilla being apparently wider in P. rubidomontanus the most notable differences
were seen in the glumes and nutlets. Both P. capillifolius and P. melas have capillary leaves and very narrow spikelets
that are rarely more than 1.5 mm wide; in addition, both are annuals. Most similar to P. rubidomontanus was found to
be Pycreus poikilostachys, an endemic of the Zambian region. Both share the usually dark brown glumes with hyaline
margins and apex and the long and erect involucral bract. P. poikilostachys, however, is an annual species with much
narrower rachilla and slightly longer glumes (ca. 2.4–2.5 mm) and nutlets (ca. 1.5 mm long).
Interestingly, an isotype of P. rubidomontanus (Adam 12732) in P is down as P. reductus Cherm., an endemic of
Madagascar, although no signs of this name are discernable on the sheet. The latter, described by Chermezon (1921), is
indeed very similar, not only in general appearance but also in details such as glumes with a narrow hyaline margin and
spikelets with an apparently straight rachilla. Its clearly oblong nutlets distinguish P. reductus from the other species,
especially from P. capillifolius.
Pycreus rubidomontanus most likely belongs to section Globosi C.B.Clarke, as does P. capillifolius (Kükenthal
1935–1936). Although Nelmes (1952) did not discuss the affinities of his P. poikilostachys, this species also probably
is a member of this section. Kükenthal (1935–1936) considered P. reductus to be part of the variable P. flavidus
(Retz.) T.Koyama, the type of the section. Although we do not agree with this viewpoint, it is obvious that both
are similar and probably closely related. All these species have a capitate, apparently pseudolateral inflorescence,
narrow spikelets, (narrowly) hyaline-margined glumes that are not closely imbricate (with rachilla showing through)
and rounded at apex, two stamens and papillose-tubercled nutlets. However, there are no apomorphies that clearly
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characterize this section and the species that were originally accommodated in it do not cluster together in molecular
phylogenetic analyses (Reynders 2013). Kükenthal (1935–1936) further included P. melas in section Globosi and the
same could then apply to the very similar P. micromelas Lye. However, these two species are more derived and may
rather belong to other groups based on nutlet micromorphology (Reynders 2013). They are not likely to be confused
with P. rubidomontanus.
FIGURE 3. Pycreus rubidomontanus. SEM of outline of nutlet and surface ornamentation (resp. 100 and 10μm) (from Adam 12732, K).
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TABLE 1. Comparison of P. rubidomontanus and similar-looking species, mostly based on type material (Adam 12732, Milne-Redhead 4565, Hoenselaar et al. 2010, Perrier de
La Bâthie 13737 and Milne-Redhead 4311 respectively)
P. rubidomontanus P. atrorubidus P. capillifolius P. reductus P. poikilostachys
Life form and growth pattern Perennial, rhizomatous and
stoloniferous in tussocks Single stemmed or tufted annual Tufted annual Densely caespitose perennial Annual
Bract (lower) Erect, up to 13 cm long Patent (spreading), 1–3.5 cm
long Erect, up to 13.5 cm long Erect, up to 5-7 cm long Erect, almost as continuation
of stem
Spikelet number (3–) 6–10 (–16) 1–7 8–30 4–8 3–8
Spikelet size (mm) 6–16 × 2–2.5 5–10 × 2–2.5 6–19.5 × 1.3–2 8–15 × 1.5–2 7–15 × 2–3
Glume Apex and margins hyaline Apex not hyaline, margin if
hyaline not obviously so Margins narrowly hyaline Apex and margins not or
narrowly hyaline Upper edges broadly hyaline
Nutlet shape Obovoid, apiculate Obovate to square-obovate Obtriangular Oblong, assymetric, scarcely
apiculate
Oblong-orbicular to oblong-
obovate
Nutlet surface Papillose, papillae obvious (Immature); indications of
possible papillae developing
Minutely tuberculate in
longitudinal rows Regularly finely punctulate Densely minutely punctulate
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DISTRIBUTION:
Widely distributed in tropical West Africa: Sierra Leone, Guinea, Liberia and Ivory Coast (Fig. 4). During our revisions
we also found collections of it from Cameroon and Nigeria. P. rubidomontanus is exclusively found in mountain
regions, ranging in altitude from ca. 1,350 m up to about 2,500 m in Cameroon and Nigeria.
FIGURE 4. Distribution of Pycreus rubidomontanus in tropical West Africa (based on herbarium specimens examined).
SELECTION OF SPECIMENS EXAMINED (in addition to the type):
CAMEROON: Dschang, Mt. Bamboutos, 1,950 m., oberhalb der Ferme Pastorale Djuttitsa, an sumpfiger Stelle
in Weideland, 29.VI.1955, A. Saxer 68 (K); Dschang District, Mt. Bamboutos near Dschang, alt. 8,000–8,200 ft.,
montane grassland, among rocks, 24.XI.1968, W.W. Sanford 5601 (K, MNHN-P-P00584793); Bambui, 1971, F. Botté
698 (MNHN-P-P00584739); North-West Region, 21 km on the road from Bamenda to Jakiri, 6°1’0”N, 10°18’0”E (=
6.016667, 10.3), 1,900 m., wind swept slope partly with bare rocks on the surface, covered by lichens, partly covered
by grass vegetation. Locally some water still seeping along the rocks, and there, on shallow soil, a rich herbaceous
vegetation, 04.XI.1975, J.J.F.E. de Wilde 8637 (WAG.1768680, MNHN-P-P00584809); North-West Region, Bui,
Elak, Shambai, 6°15’0”N, 10°25’0”E (= 6.25, 10.416667), grassland, 05.XI.1996, M.P. Munyenyembe, F.M. Mbago &
P. Lem 876 (WAG.0375722);
GUINEA: Monts Nimba, VIII.1954, R. Schnell 2641 (K, MNHN-P-P00584800, MNHN-P-P01733846); Mt.
Nimba, Nzérékoré, 1,800 m., X.1937, J. Felix 1923 (K, MNHN-P-P00584802); Mt. Nimba, Nzérékoré, 1,550 m.,
s.d., C. Farron 247 (WAG.1941701, WAG.1941702); Nzérékoré, Mt. Nimba, 28.X.1971, J.-G. Adam 26519 (MNHN-
P-P00584736); Nzérékoré, Nimba Mountains, Mare d’Hivernage, 7°39’40”N, 8°22’46”W (= 7.661167, -8.379667),
naturally yearly inundated area, 1,612 m., 15.VII.2007, C.C.H. Jongkind, J-L. Holié & P. Cherif 7967 (WAG.1768681,
MNHN-P-P01786961); Nzérékoré, Nimba Mountains, plot JRMH01, 7°39’40”N, 8°22’46”W (= 7.661167, -
8.3795), 1,613 m., humid depression between higher hills, soil humid, stony, 27.XI.2007, Nimba Botanic Team 672
(WAG.1770160); Dalaba, between Koumbouroaguaminet and Diaguissa, 1,316 m, temporary wet grassland on laterite,
common, 18.X.2016, I. Larridon 14 (K, dupl. HNG, GENT);
IVORY COAST: Nimba Mt., 4,500 ft., C.C. Boughey GC18164 (K); Danané, Mount Nimba, on moist place
among boulders, 15.XII.1967, C. Geerling & J. Bokdam 1761 (WAG.1770158);
LIBERIA: Nimba, 1,600 m., rochers, 06.XI.1969, J.-G. Adam 24704/2 (MNHN-P-P00584796, MNHN-P-
P00584798, MNHN-P-P00P00584796);
NIGERIA: Sardauna province, Gangirwal, in crevice in soft rock in stream bed, 24.XI.1974, J.D. Chapman 3575
(FHI0102084-0);
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SIERRA LEONE: [unreadable], marécage sommet, P. Jaeger 7886 (K); sommet Pic Bintumani, station humide,
XI.1944, P. Jaeger 400 (K); Kabala, Mont Loma, 03.XII.1965, J.-G. Adam 22350 (MNHN-P-P00584734, MNHN-P-
P00584735); Kabala, Mont Loma, 15.XII.1965, J.-G. Adam 29274 (MNHN-P-P00584738);
HABITAT:
Pycreus rubidomontanus is always found in damp places, often temporarily humid depressions in montane grassland
or between rocks. It is most often seen in wet flush vegetation between bare stones and tall herbaceous vegetation mats.
Furthermore, it can be observed on the edge of montane streams. In Nigeria, it has also been collected in crevices of
soft rock in a regularly flooded stream bed.
PRELIMINARY IUCN RED LIST ASSESSMENT:
This species is mainly collected from Nimba Mountains, probably because this area is easy-to-access from Liberia,
Ivory Coast and Guinea. However, it may be even more abundant on summits of Loma Mountains. It also occurs in the
Fouta Djallon highland region in the center of Guinea. In both Cameroon and Nigeria there are high mountain areas
that provide good habitats for this species. There are relatively few human activities in these high-altitude regions
and most localities are protected. However, most of natural open habitats have been destroyed in the Liberian part of
Nimba Mountains due to mining activities; therefore, this species is probably extinct in that country. Since most parts
of the Nimba Mountains consist of iron ore, companies may be interested in its exploration, especially in the Guinean
part, in spite of legal protection. A potential future threatening factor could also be climate change, although there is
no evidence for that. Spatial analysis and IUCN conservation assessments made using GeoCat (Bachman & al. 2011)
gave the following results. Extent of Occurrence (EOO) was estimated at 624,500 km² based on about 20 collections,
representing the known species range, giving an assessment of Least Concern (LC). Area of Occupancy (AOO) was
20 km², based on the IUCN default 2 × 2 km cell, giving an assessment of Endangered (EN).
PHENOLOGY:
The type collection was made in October. It includes spikes in anthesis, as well as others with mature achenes. Other
collections examined were made between June and August and September and December. This is consistent with
flowering and fruiting time during or shortly after the rainy season periods in the southern part of tropical West Africa
(mostly from the end of April to mid-July and in September and October).
ETYMOLOGY:
The specific epithet refers to the apparently exclusively mountainous areas in which the new species is found (all
located well above 1,000 m altitude) and the strikingly dark color of the spikelets, ranging from dark red to almost
black.
NOTES:
Recent molecular studies have shown Pycreus P.Beauv. to be nested in a paraphyletic Cyperus L. s.s. and therefore
should be viewed as part of a broadly circumscribed genus Cyperus (Larridon & al. 2013, 2014). Although we concur
with this point of view, the new species is here described as member of the genus Pycreus because the name is
needed for an upcoming account on West African Cyperaceae that applies a more conservative taxonomic approach,
recognizing genera like Ascolepis Nees ex Steud., Kyllinga Rottb., Lipocarpha R.Br., Pycreus and others (Mesterházy
& al., in prep.). A combination in Cyperus will be made after publication of this paper.
Acknowledgements
The authors would like to thank Iris Van der Beeten for preparing the SEM photos and Dr. Elmar Robbrecht (both
Botanic Garden Meise) for his advice on the Latin epithet of the new species. Isabel Larridon (Royal Botanic Gardens
Kew) and Marc Reynders (Botanic Garden Meise) are thanked for their most valuable comments.
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