The genera of Cyperaceae of Madagascar

Background and aims – The rise of DNA sequencing in systematics has brought more understanding of the Cyperaceae family worldwide. Through these studies, it has been possible to delineate major clades and classify its species into subfamilies, tribes, and genera. Today, we have a good understanding of the species diversity and geographic distribution of the genera. However, in the case of Madagascar, the only complete taxonomic treatment of Cyperaceae dates from 1937. Although recent monographs exist for some genera in Madagascar, the taxonomic treatment of the Cyperaceae of Madagascar has not been updated until now. Hence, the present work aims to produce an updated treatment at the generic level including descriptions and an identification key of all Cyperaceae genera in Madagascar. Material and methods – Books and scientific articles containing descriptions of the genera of Cyperaceae of Madagascar, and information on their ecology and distribution were consulted, as well as herbarium specimens, collections, and data available from online herbaria and aggregator portals. Key results


INTRODUCTION
Madagascar, with its area of 592,000 km 2 , is home to ca 310 species of the Cyperaceae family (Larridon et al. 2021a). These 310 species are classified into two subfamilies, i.e. Cyperoideae and Mapanioideae, each of which includes several tribes and genera (Larridon et al. 2021b). The evolution of technology in systematics has brought much more understanding for the Cyperaceae family worldwide. Through these studies, major groups such as the two subfamilies (Cyperoideae and Mapanioideae) and different tribes and genera have been delineated (Larridon 2022a). Although much taxonomic work remains at the species level, we have a good understanding of species diversity per genus and the geographic distribution of species (Jung et al. 2016;Semmouri et al. 2019;Muasya and Larridon 2021;Larridon 2022a). However, in the case of Madagascar, the only taxonomic treatment of the family, Chermezon's Flore de Madagascar, dates from 1937, although research has been done since then on a few genera (Díaz et al. 2019;Larridon et al. 2019), the taxonomic treatment of the Cyperaceae of Madagascar Table 1. Overview of the genera occurring in Madagascar and their subfamily and tribal placement following Larridon et al. (2021b), and ordered according to Larridon (2022a).

TAXONOMIC TREATMENT
Identification key to subfamilies, tribes, subtribes, and genera of Cyperaceae of Madagascar 1.
Leaf blade absent; inflorescence always a single spike; predominantly in temperate and subtemperate heathlands and swaps .. Inflorescence variable, often paniculate or spike-like on upper part of stem; spikelet bisexual with 1 female floret; if all spikelets unisexual, then female spikelets with reduced male flowers, or with reduced rachilla apex; male flower usually with 3 stamens; contraligule usually well developed; nutlet usually large, well distinct at maturity, smooth or ornamented, egg-shaped, pale and often white, with hypogynium (hardened gynophore) at base sometimes cupuliform (sometimes reduced

Tribe Trilepideae
Coleochloa Gilly (Gilly 1943    Type species. Scleria flagellum-nigrorum P.J.Bergius Description of the genus. Habit variable, from tiny annuals with fibrous roots to perennial climbers more than 10 meters tall; stoloniferous rhizome or tubers; aerial adventitious roots at stem nodes (adaptation to flooded habitats). Culms trigonous or triquetrous, noded bearing leaves often without ligules, sometimes with a contraligule. Leaves alternate, tristichously arranged, often persistent at the base, and finely serrate at least along the distal third of the margins, rarely smooth: sometimes abruptly narrowed down or pseudopraemorse; sheaths sometimes winged, usually topped by a contraligule, opposite to the blade. Inflorescence bracts leaf-like and sheathing, setaceous, or glume-like; spikelet bract usually setaceous, rarely glume-like. Inflorescence variable, usually paniculate, but often with contracted partial inflorescences. Spikelets bearing flowers of one or both sexes, the bisexual ones with one basal female and one to few male flowers above; female spikelet similar but upper part reduced to 1-2 empty scales or wanting; male spikelet lacking basal female flower and with more male flowers. Glumes in androgynous or bisexual spikelets the lower part is female with distichously arranged glumes (a few may be empty), upper part male with few to many spirally arranged glumes. Florets always unisexual, enclosed by at least three glumes. Bristles absent. Stamens 1-3, anthers often linear, more or less apiculate. Style 3-fid; ovary surrounded at the base by a variously shaped (sometimes reduced) lobed hypogynium, which is shed with the fruit. Nutlets globose to ovoid, variously sculptured and ornamented, usually white, sometimes beaked, subtended by a cupule, frequently surrounded by a hypogynium. Distribution and ecology. Scleria is widely distributed in the tropics and subtropics up to North America (POWO 2022). It grows in seasonally damp or permanently wet habitats, woodland, forests stream sides, and grasslands (Browning and Goetghebeur 2017). Scleria occurs throughout Madagascar. The 25 previously known species, including e.g. Scleria bulbifera Hochst. ex A.Rich. (Fig. 7) and Scleria distans Poir. (Fig. 8A), were recently monographed (Díaz et al. 2019), and a new species has been recently discovered from northern Madagascar (Larridon et al. unpubl. data).
Distribution and ecology. Costularia occurs in southeastern Africa, Madagascar, the Mascarenes, and Seychelles. It grows on rocky ground in forest, grassland, or ericoid vegetation, sometimes along streams or in swamps, usually at higher elevations. In Madagascar, Costularia is known from north to south along the mountain ridge and high elevation areas, including the Central Highlands. The genus was recently monographed , and 11 species are native to Madagascar, including e.g. Costularia itremoensis Larridon (Fig. 4B) and Costularia pantopoda C.B.Clarke (Fig. 9).  (Fig. 10).
Nutlets usually lenticular to globose. Embryo top-shaped in frontal view, root cap developed in a (sub)basal position, and first leaf primordium developed in a lateral position (Carex-type embryo). Distribution and ecology. Rhynchospora is a cosmopolitan genus (POWO 2022). It grows in seasonally wet to permanently flooded grassland, laterite outcrops, lake shores, stream sides, swamps, rice fields (Browning and Goetghebeur 2017). Rhynchospora occurs throughout Madagascar; ten species are known including e.g. Rhynchospora holoschoenoides (Rich.) Herter (Fig. 11) and Rhynchospora angolensis Turrill (Fig. 12A). Leaves generally present, glabrous or rarely hairy, sheath often surrounding culm, ligule or sometimes contraligule present at the junction of the sheath and the blade. Primary bracts leaf-like or not, sheathing or not. Partial inflorescences spike-like, unisexual or bisexual, with few to many spirally arranged bracts (or glumes), either subtending a female spikelet or a male floret. Inflorescence terminal, rarely pseudolateral, paniculate, often partly or completely contracted, rarely corymbose or anthelate with few to numerous spikes, less frequently reduced to a single spike, cladoprophylls sometimes swollen at the base, utriculiform and subtending a female floret; inflorescence mostly bisexual, rarely unisexual or florets dioecious. Spikes male, female, or bisexual, and then mostly male florets apically, rarely basally, or intermingled; female spikelet reduced to the rachilla and a utriculiform, flower-bearing prophyll, completely enclosing the rachilla.     Distribution and ecology. Eleocharis is a cosmopolitan genus (POWO 2022). It grows in forest, wet grasslands, freshwater wetlands, along rivers, lake margins, and rice fields, and in rocky areas. Eleocharis occurs throughout Madagascar; 12 species are known including e.g. Eleocharis acutangula (Roxb.) Schult. (Fig. 4C) and Eleocharis dulcis (Burm.f.) Trin. ex Hensch. (Fig. 13).  (Fig. 8B) and Bulbostylis hispidula (Vahl) R.W.Haines (Fig. 14).

Tribe Pseudoschoeneae
Schoenoplectiella Lye (Lye 2003: 20) Type species. Scirpus articulatus L. [= Schoenoplectiella articulata (L.) Lye] Description of the genus. Annuals or perennials, tufted or with firm, short to creeping rhizomes. Culms nodeless and scapose or 1(-3)-noded above the base, trigonous, terete or rarely 7-sided. Leaves reduced to a mucronate sheath, rarely with well-developed blades, ligulate or eligulate. Involucral bracts culm-like, erect, or patent while fruiting, rarely short, rigid, and sheathing, but then appearing as a continuation of the stem. Inflorescence pseudolateral, rarely appearing terminal, a corymblike anthela or capitate with 1-many spikelets, rarely compound-paniculate with 1-many spikelets, with a conspicuously sinuous main axis. Glumes many, spirally arranged, deciduous or persistent, each subtending a flower; scale apex entire to apiculate. Floret bisexual, rarely polygamodoecious. Perianth bristles present or absent, formed by 0-10 parts, smooth or retrorsely scabrid, bristle-like, as long as or longer than the nutlet, deciduous with the fruit. Stamens 2-3, rarely vestigial in female flowers. Style 2-3-fid, base undifferentiated, rarely     Description of the genus. Small to more rarely mediumsized tufted annuals or mat-forming perennials; rhizome more rarely creeping, rhizomatous or stoloniferous. Culms scapose or with few to many nodes. Leaves eligulate, of a minute lobe or elongated to form a linear blade often much reduced. Primary bracts leaf-like or short, not sheathing, lowermost bract often erect. Inflorescence often pseudolateral, capitate, rarely anthelate. Spikelets few to many or reduced to a single spikelet. Glumes with few to many usually spirally arranged (rarely distichous), mostly deciduous glumes, each subtending a floret. Floret bisexual. Perianth bristles absent. Stamens 1-3; filament ribbon-like, anther crested with minute spikes. Style deeply 2-3-fid; base not distinct, not or slightly thickened, persistent. Nutlets mostly obovoid, thick lenticular to (rounded) trigonous, often 3-ribbed, beaked, surface with various ornamentations. Distribution and ecology. Isolepis is a cosmopolitan genus (POWO 2022). It grows in temporary and permanently wet areas. In Madagascar, Isolepis is known from the north and the Central Highlands; four species are known including e.g. Isolepis fluitans (L.) R.Br. (Fig. 21).

Ficinia
Schrad. (Schrader 1832: 143) Type species. Schoenus filiformis Lam. [= Ficinia filiformis (Lam.) Schrad.] Description of the genus. Small to medium-sized tufted perennials; frequently with a short or elongated creeping rhizome, stoloniferous, or decumbent. Culms scapose, more rarely with few to many nodes or branched, rarely thickened at the base, leafy only at the base or in all their length. Leaves often conspicuously ligulate (rarely eligulate), blade sometimes with scarious margins, or leaf reduced to a sheath. Primary bracts leaf-like (rarely bright yellow) or short, not sheathing, lowermost bract sometimes erect. Inflorescence rarely pseudolateral, mostly capitate, more rarely compacted, paniculate, spicate, or spikelets scattered along a profusely branched stem. Spikelets 1many. Glumes with few to many spirally arranged or more rarely distichous, usually long-persistent glumes, each with a floret, or a few lower glumes empty. Floret bisexual. Perianth bristles absent. Stamens 3; anthers linear, often apiculate or setiferous. Style deeply 3-fid, sometimes 2-fid, rarely almost undivided; base not distinct, not thickened, deciduous. Nutlets mostly obovoid, rounded trigonous, rarely biconvex, base mostly surrounded by a tightly enveloping cupular to 3-lobed disc (gynophore), surface usually smooth. Distribution and ecology. Ficinia is a cosmopolitan genus (POWO 2022). It grows in wet or dry mountain grasslands (Browning and Goetghebeur 2017). In Madagascar, Ficinia is known from the Analamanga region of Antananarivo province. Only a single endemic species is known from Madagascar, i.e. Ficinia ciliata Boeckeler. No illustration is available of this species and the type material has not been located.  (Domin 1915: 415) Courtoisina Soják (Soják 1979(Soják publ. 1980 Type species. Cyperus esculentus L. Description of the genus. Small to large annuals, or tufted, rhizomatous, stoloniferous or bulbiferous perennials. Culms mostly scapose, triangular to subterete, rarely winged, compressed or septate. Leaves eligulate (more rarely ligulate), sometimes reduced to a sheath; sheaths sometimes semisucculent; blade linear or rarely oblong or pseudopetiolate. Primary bracts often large and leaf-like, not sheathing, lowermost bract rarely erect. Inflorescence of few to many spikelets, in clusters called spikes, terminal, rarely pseudolateral, anthelate to capitate, rarely spicate or reduced to a single spikelet; partial inflorescences spike-like with spicately or digitately-arranged spikelets, or densely capitate. Spikelets with few to many, 2-ranked (very rarely spirally arranged) glumes, spikelet bract and prophyll more or less glumelike, each glume subtending a floret. Glumes deciduous or persistent; rachilla internodes elongated. Floret bisexual, very rarely unisexual or even dioecious. Bristles absent, lacking a gynophore. Stamens 1-3. Style (2-)3-fid, more rarely (sub)entire; base mostly not distinct, not thickened, persistent or deciduous. Nutlets most often 3-sided, with  the flat side pressed against the spikelet rachilla, often obovoid or ellipsoid, rarely dorsiventrally compressed, rarely stipitate, beaked or not, surface smooth or with various ornamentations, rarely thickened, corky. Distribution and ecology. Cyperus is a cosmopolitan genus who can be found everywhere. Cyperus occurs throughout Madagascar; ca 145 species are known including e.g. Cyperus pectinatus Vahl (Figs 22, 23).