Taxonomic revision of the tropical African group of Carex subsect . Elatae ( sect . Spirostachyae , Cyperaceae ) by

Escudero, M. & Luceño, M. 2011. Taxonomic revision of the tropical African group of Carex subsect. Elatae (sect. Spirostachyae, Cyperaceae). Anales Jard. Bot. Madrid 68(2): 225-247. The tropical African monophyletic group of Carex subsect. Elatae (sect. Spirostachyae) is distributed in continental tropical Africa, Madagascar, the Mascarene archipelago, and Bioko Island (32 km off the coast of West Africa, in the Gulf of Guinea). The first monographic treatment of this Carex group, as well as of the tribe Cariceae, was published by Kükenthal (as sect. Elatae Kük.). Recently, the first molecular (nrDNA, cpDNA) phylogeny of Carex sect. Elatae has been published, which also included the species of sect. Spirostachyae. In the resulting consensus trees, most species of sect. Elatae were embedded within core Spirostachyae and so this section was joined with sect. Spirostachyae as subsect. Elatae. Within subsect. Elatae, several groups were described, one of which was termed the “tropical African group”. Here we present a taxonomic revision of this group, based on more than 280 vouchers from 29 herbaria as well as in field trips in Tropical Africa. In the revision, we recognise 12 species (16 taxa) within the tropical African group, and so have somewhat modified our previous view, in which 10 species, 12 taxa were listed. One new species from Tanzania is included in this treatment, C. uluguruensis Luceño & M. Escudero. Several combinations are made, C. cyrtosaccus is treated as a synonym of C. vallis-rosetto and, finally, the binomial C. greenwayi has been recognised.


Introduction
The tropical African group of Carex subsect.Elatae (sect.Spirostachyae) is a monophyletic group according to nrDNA phylogeny, but not according to cpDNA phylogeny (Escudero & Luceño, 2009).This group is distributed along continental tropical Africa as well as Madagascar and the Mascarene and Bioko Islands.Lamarck (1792) described the first species of this Carex group from Reunion Island (C.borbonica); other taxa were subsequently described: C. boryana (Schkuhr, 1806), C. petitiana and C. simensis (Richard, 1850), C. fischeri, C. vallis-rosetto, andC. lon gipedunculata (Schumann, 1895).Clarke (1902) treated the continental species of this group in his Flora of Tropical Africa (seven species in total, one of them, C. cyrtosaccus, as new species; Table 1), but he did not refer them to any supraspecific category.The first monographic treatment of this Carex group, as well as of tribe Cariceae, was published by Kükenthal (1909).He included 19 species in the new sect.Elatae Kük., eight of which (15 taxa) were from the tropical African group (Table 1).In this monographic work, one new species (C.mildbraediana) as well as five new varieties and two new combinations were published (Table 1).Subsequently, Kükenthal (1914Kükenthal ( , 1925Kükenthal ( , 1934; Table 1) published numerous modifications to his original taxonomic treatment of sect.Elatae (Kükenthal, 1909, Table 1), in which one subspecies, six new varieties and two new forms were described and a new combination was made.Nelmes (1938) revised the group and described four new taxa (three species and one variety) and published a new combination.Subsequent treatments were local, as in the Flora of West Tropical Africa (Hooper & Napper, 1972; two species), or The Sedges and Rushes of East Africa (Haines & Lye, 1983; seven species, Table 1).
More recently, Luceño (1992) and Luceño & Castroviejo (1993) studied five taxa which were included in sect.Elatae by Kükenthal (1909) but none were from the tropical African group.Escudero et al. (2008) made the first molecular (nrDNA) phylogeny of Carex sect.Spirostachyae in a study that also included seven species previously treated in sect.Elatae by Kükenthal (1909), one of which was from the tropical African group (Carex mannii).These seven species were included in the core Spirostachyae in the molecular phylogeny.Escudero & Luceño (2009) performed the first molecular (nrDNA, cpDNA) phylogeny of Carex sect.Elatae that also included the species of sect.Spirostachyae.Again, most species of sect.Elatae were embedded within core Spirostachyae and accordingly, sect.Elatae was included in sect.Spirostachyae as susbsect.Elatae.Therefore, the new taxonomic concept of this section includes 11 species traditionally considered in sect.Spirostachyae and 16 species traditionally included in sect.Elatae (Escudero & Luceño, 2009).Within subsect.Elatae, several groups were described, among them the tropical African group (Escudero & Luceño, 2009).This group contained ten species, eight (ten taxa) from continental tropical Africa and three species from Madagascar, and the Mascarene and Bioko Islands (one of them in the continent too).In addition, two new combinations were made (C.mannii ssp.thomasii and C. mannii ssp.friesiorum) (Table 1).Finally, a checklist of sub-Saharian African Carex species has been recently published (Gehrke, 2011).The general goal of this study is to provide a taxonomic treatment of this controversial tropical African group of Carex.The specific aims are: 1) to establish the taxa that belong to this group, 2) to specify the taxonomical level of the taxa (species or subspecies), 3) to delineate the morphological differences between the taxa and provide taxonomic keys, 4) to describe the new taxa which are necessary, and 5) to perform a nomenclatural revision.

Material and methods
More than 280 herbarium vouchers were studied for the present taxonomic revision (see Appendix 1).These materials are from 29 herbaria (B, BM, BR, C, E, EA, GOET, H, HUH, K, L, LD, LISC, M, MA, MO, NBG, NU, NY, O, OXF, PRE, U, UPOS, UPS, US, W, WAG, WU; Index Herbariorum, http://sweetgum.nybg.org/ih/).In addition the website JSTOR (http://www.jstor.org/)which contains images of type material of African species was frequently consulted in the present revision.Seventy morphological characters were considered in the study, comprising 37 qualitative characters and 33 quantitative characters.We paid special attention to the characters previously stated as important in the taxonomy of sect.Spi ros tachyae (Luceño & Escudero, 2008).Quantitative characters were measured using a stereoscopic bi no cular Nikon SMZ645.

Clarke
Unknown type.
Comments: Some specimens display intermediate features between C. boryana and C. borbonica, suggesting hybridization, and probably introgression, between these two taxa.We have observed in the field (Le Maïdo, near Malfate circus) both pure species in their typical habitats, with neighbouring populations Taxonomic revision Carex tropical African group growing in intermediate habitats (open and stony scrublands of Philippia montana) whose individuals showed a gradient of characters between the putative parentals.This hybridization hypothesis is in agreement with our molecular data (Escudero & Luceño, 2009).Many of these morphologically intermediate specimens have been described as different taxa: -Carex borbonica var.pallidior Kük., Engl. (ed.)Although the type material of C. musei (P 541690!) is very similar to pure individuals of C. boryana, the short female glume aristas and most spikes arising near the apex of the stem lead us to think it is an introgressive form of the latter species with C. borbonica.
Carex borbonica was thought to be also distributed on Mauritius island by Kükenthal (1909;"Mauritius (in herb. Lamarck!)").However, all studied materials of C. borbonica from Lamarck's herbarium were collected from Reunion where this species grows on volcanic soil above 2250 m, while on Mauritius the highest point is the Piton de la Petite Rivière Noire (828 m).Moreover, although Baker (1877) included C. bor- bonica in his Flora of Mauritius, this author indicated: "I have not seen Mauritian specimens".For all these reasons, the references of this species for Mauritius are most likely mistaken.
Comments: Some specimens of C. mannii ssp.mannii from the Aberdare Ranges are similar to forms of C. greenwayi, but are smaller than plants of this species and at least some spikes are not androgynous.
Jan.-Dec.Wet grasslands and peat bogs; 1800-2100 m; Burundi (Ryarusera and Bugarama) and Rwanda (Rukarara).Comments: We have not seen type material of Carex mildbraediana var.alpicola Kük., (Notizblatt des Botanischen Gartens und Museums zu Berlin-Dahlem, 9: 314.1925.Type: "Mt.Aberdare: Alpine Region an einer feuchten Stelle", R.E.Fries & T.C.E.Fries 2671) and are, therefore, unable to confirm whether it is different to typical C. mildbraediana.The putative isotype material of Carex mildbraediana J. Mildbraed 966 (K363486 photo!) comprises just a few utricles.Carex ramosipes has ussually been treated as a synonym of C. mildbraediana (a species showing bidentate or truncate utricles).The studied materials (type materials) of C. ramosipes show bifid utricles as well as all materials of C. greenwayi.Nevertheless, we advise against treating C. ramosipes as a synonym of C. greenwayi since the observed specimens show some deviant features from the typical C. greenwayi morphos from Tanzania.More data are needed to elucidate if C. ramosipes might be considered an independent taxa or a simple deviant form of C. mildbraediana.The possible isotype material of Carex ramosipes [H.Humbert 7939, K363481 photo!] is only made up of a few utricles.