A revision of Heterolepis Cass. (Asteraceae: Cichorioideae)

a The Compton Herbarium, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Newlands, Cape Town 7735, South Africa b Bolus Herbarium, Department of Biological Sciences, HW Pearson Building, University of Cape Town, Rhodes Gift, 7707, Rondebosch, Cape Town, South Africa c Department of Botany, Rhodes University, PO Bosc 94, Grahamstown 6140, South Africa d Selmar Schonland Herbarium, Albany Museum, Somerset Street, Grahamstown 6139, South Africa


Introduction
The Asteraceae subfamily Cichorioideae is diverse in southern Africa, housing several large genera such as Berkheya Ehrh. and Arctotis L., as well as a number of small, morphologically unusual genera such as Eremothamnus O.Hoffm., Hoplophyllum DC. and Platycarpha Less. Heterolepis Cass. is one of these small and curious genera, comprising four species, all distributed in the winter-rainfall Cape Floristic Region (CFR) of South Africa. All species of Heterolepis are small shrublets with narrow leaves and solitary, usually radiate yellow capitula. They possess an unusual combination of micromorphological characters that has led to conflicting phylogenetic placements by different authors, sometimes in different subfamilies of the Asteraceae.
Three species of Heterolepis are poorly-known, but one, the largeflowered Heterolepis aliena (L.f.) Druce, is not uncommon throughout the drier parts of the western CFR ( Fig. 1) where it is well-collected, and known by the name 'rotsgousblom' ("rock daisy"). The remaining three taxa are Heterolepis peduncularis DC., a species with smaller capitula and much longer peduncles, which is found predominantly on shale soils on the southern Cape coastal forelands; H. anomala J.C.Manning & Goldblatt, a recently-described species with discoid capitula; and the distinctive H. mitis (Burm.f.) DC., a small radiate rock-crevice specialist that occurs only in a range of mountains in the Eastern Cape.
Heterolepis has not been revised since Harvey and Sonder (1865) and there has been no modern compilation of taxon descriptions, nomenclatural history, distribution maps or illustrations. Although H. aliena is well-represented in herbaria, the remaining three species, including the recently described H. anomala (Manning and Goldblatt, 2011), are narrowly-distributed, poorly known, and likely to be of conservation interest. A compilation of all known information on the genus, together with a comprehensive investigation of morphology and the publication of illustrations and distribution maps, is an important step towards increased knowledge of this anomalous and poorly-known genus.
captured on the SANBI specimen database were encoded from the photographs of herbarium specimens, and the data on already-captured specimens was checked and corrected, if necessary, in the same way. All specimens were databased and those with sufficiently precise locality information were georeferenced to quarter-degree grid square (QDS). Georeferenced localities were used to produce species distribution maps (mapped to QDS centroid) in Arcview. Morphological measurements were taken with precision calipers off at least ten specimens per species unless otherwise indicated. Heads from at least three specimens of each species were rehydrated in boiling water and dissected under a stereomicroscope to obtain counts of floret number; where fewer specimens were available, this is indicated in the text. Micromorphological features were examined in dried material rehydrated in boiling water under a dissecting microscope, the images being captured with a digital imaging system. Measurements were taken on the captured images using a calibrated digital imaging software, or by calibrated drawings produced via a drawing tube attached to a dissecting stereoscope. Cypsela hairs were investigated by mounting rehydrated hairs in a fuchsin-stained glycerine jelly melted under a coverslip using gentle heat; the hairs were examined in a stereomicroscope under 100× magnification.
A full list of all names associated with Heterolepis is provided in Appendix A, while the history of relevant taxonomic work is outlined in Appendix B.

Species concepts
The species concept followed here corresponds to the theoretical precepts of the evolutionary species concept, in which a basic unit in evolution corresponds to an ancestor-descendant sequence of interbreeding populations with its own separate and unitary evolutionary role and tendencies (Simpson, 1951(Simpson, , 1961Wiley, 1978). Fixed morphological differences as observed on herbarium specimens were used as evidence for evolutionary independence; thus the species defined here will correspond with those defined on purely morphological grounds.

Habit
All Heterolepis species are shrublets. They vary in height (from 20 cm to over 100 cm high) and degree of branching, from well-branched and rounded to sparsely branched and erect. Two species are strongly associated with rocky habitats or root in rock crevices, while the remaining two grow in soil in open shrubland. Some species have a degree of development of a woody rootstock and resprout after fire or disturbance. Apical growth is terminated by the flowerhead, with growth in subsequent years initiating from well below the point of attachment of the old head.

Trichomes
Heterolepis species possess multicellular, biseriate trichomes on the peduncles, involucral bracts, corolla tube and corolla lobes. There appear to be at least three, possibly up to four or five, different types of trichomes, although a detailed ultrastructural investigation would be required to determine differences in trichome structure, and the apparent differences may be due to variations in the volumes of cells in different parts of the trichome. All the trichome types comprise a distinct, usually biseriate stalk, and a separate head structure. We have distinguished the types based on both their position and shape.

Trichome type A
This is the largest type of trichome and occurs on the peduncles and involucral bracts (Figs. 2b,e;4c,e;6a). The base has a conical shape with a broad, somewhat sprawling multicellular basal section narrowing to a slender stalk which is made up of a double row of cells. The head is relatively small and may be spherical or oblong and appears to comprise many small stacked cells, also in a double row, and often with darkened portions that may be pigmented cell contents or thickened cell walls. These trichomes attain their greatest size in the central portion of the involucral bracts, where the bases can be especially large; the trichomes on the bracts and peduncle are, however, quite variable in size so that any portion of the peduncle or central part of the involucral bract comprises a mix of differently-sized trichomes. The cells of these structures are generally filled with a dark red-purple pigment. On the involucral bracts these glands are bent and directed upwards (towards the bract apex), while on the peduncle they are straight, being directed outwards. On the margins of the bract, the trichomes contain less pigment and are often more slender, and lack the broad sprawling base.

Trichome type B
This trichome type appears to have a very similar basic structure to type A. It occurs on the corolla tubes of both rays and discs nearly in all species (Fig. 4g,h,k). It differs from type A in being more slender, with a narrower base, so the overall shape is hair-like or elongateclavate. It also lacks the red pigment. Slender, segmented, headless trichomes on the corolla lobes of H. anomala (Fig. 6d,g) may be a variation of this type, or may be a different type of trichome entirely. ; cleaves below immature capitulum (scale bar = 9.0 mm); dmature capitulum (photo by Jon Richfield, Wikipedia; scale bar ≈ 20 mm); edensely glandular peduncle (scale bar = 40 mm); finvolucre, showing the basal fusion of the bracts, the fleshy, herbaceous texture and glandular indumentum of the outer bracts and peduncle, and the membraneous apices and margins of the inner bracts (scale bar = 30 mm); ginvolucral bract series with outermost at left and middle at right (scale bar = 2.2 mm); hinvolucral bract series with inner at left and innermost at right (scale bar = 2.2 mm); idisc floret, post-anthesis (scale bar = 3.4 mm); janthers of disc floret showing obtuse, flat apices and tailed, calcarate bases (scale bar = 0.93 mm); kanther tails (scale bar = 0.7 mm); lray floret corolla showing the filiform lobe (arrow) in the tube sinus (scale bar = 2.0 mm); mstyle branches of disc floret (scale = 0.8 mm). All photos by N. Bergh unless otherwise indicated. Images b, e, f, g, h, i, k, l and m taken from rehydrated material of Compton 21178 (NBG).

Trichome type C
Apart from the elongate types A and B, there is at least one type of sessile, clavate trichome occurring on various parts of the plants. Sessile trichomes appear to be scattered amongst the longer A-type glands on the involucre of H. anomala, but these may just be short variants of the A-type. The young stems of Heterolepis mitis bear oblong trichomes that may be responsible for a resiniferous covering sometimes visible in this species. However, the corolla lobes of Heterolepis mitis bear on their abaxial surfaces very short stalked globular-headed glands (Fig. 3c) that appear to have a much simpler cellular structure than any of the glands mentioned thus far. These we have called gland type C.

Stems
At least one species (H. aliena) possesses white milky sap in the young branches, but this character is not observable in dried specimens and has not been investigated in the other species. The lower parts of the stems are frequently bare, with leaves borne towards the ends of the branches. The stems are thin-barked and glabrous, or alternatively white-woolly, and are sometimes glandular.

Leaves
Leaves are alternate and erect to spreading, straight or slightly incurved. Most species have leaves that are leathery in texture, ericoid, sclerophyllous and narrow (Figs. 2c;4e;5). In three of the species, the leaves are linear-oblong to narrowly oblanceolate, sessile, with a somewhat thickened and leathery texture, an acute to rounded and shortly mucronate leaf apex and leaf margins that are entire or obscurely minutely and sparsely toothed. The margins are also revolute. The adaxial surface is glabrous or sparsely white-woolly becoming glabrescent, while the abaxial surface is densely to sparsely white-woolly except on the somewhat enlarged abaxial midrib. The leaves of Heterolepis mitis (Fig. 3b) differ from those of the other species in being glabrous, thin and shiny, and in frequently having a short petiole-like narrowed base.

Peduncles
The peduncle comprises the apical portion of the shoot (Fig. 5) and is unbranched and leafless, although it may bear a few bracts. Peduncle length is one of the characters that distinguishes species in Heterolepis, varying from very short in Heterolepis mitis (Fig. 3b) to more than 20 cm long in H. peduncularis (Fig. 5a). Peduncles are often longitudinally striate and may be densely glandular, particularly near the capitulum (Figs. 2e,f; 4c,e); peduncular bracts bear the same glandular covering as the peduncle. In species with distinct peduncles, the vestiture of the peduncle is markedly different to that of the stem.

Capitula and receptacle
Capitula are always solitary in Heterolepis, and are generally radiate, with only H. anomala being consistently discoid. The rays, when present, are borne in a peripheral whorl and are female fertile, while the discs are always hermaphrodite. Capitula are smallest in H. mitis, and largest in H. aliena. Paleae are absent. The receptacle is alveolate, and the alveole margins have short, irregular projections (Fig. 3j). The receptacle becomes somewhat woody with age.

Involucre
The involucre in Heterolepis comprises 2-4 indistinct series of imbricate bracts, fused at the base to form a cup with a flattish, rounded or concave base (Figs. 2f;3b;4c,d). The outer bracts are the smallest and narrowest, and are entirely fleshy, subulate, herbaceous and green with an acute apex and a dense covering of stout glandular trichomes of type A (Figs. 2g; 4f; 6a). Bract structure undergoes a transition from the outermost to the innermost, the transition involving an increase in size and a decrease in the proportion of the bract that is fleshy, this being confined to an increasingly smaller basal portion. In contrast, increasing proportions of the bract apex and margins become membraneous, thin, glabrous, brown and translucent (Figs. 2f,h;4f;6a). The membraneous margin is often serrate and drawn into fine points. The bracts become dark brown with age.

Anthers
Fertile anthers are present only in the disc florets, while the rays possess staminodes. The fertile anthers are calcarate and shortly caudate with obtuse, un-or barely-branched and slightly curled tails (Figs. 2j,k; 3h,k; 6g). The filament collar is oblong and conspicuous. The apical appendages are obtuse, truncate or bifid and are thin, soft and flat (Figs. 2j; 3h; 4l; 6g,h). The staminodes are smaller than the fertile anthers, but otherwise similar in structure, and protrude slightly from the ray floret corolla tube (Figs. 3l; 4m).

Style
Styles do not vary between the ray and disc florets; they are terete, slender and glabrous with a swollen base, and protrude at length from the corolla tubes (Figs. 2d;3b;4b,c,k;6b,d). The apical ends of the style branches are rounded to acute, obtuse or truncate with the stigmatic region covering the entire adaxial surface of the branches. Style branches are densely covered in very short, acute papillae that extend down the style to below the point of bifurcation, where they end abruptly, with or without a ring of longer sweeping hairs on a slightly thickened portion (Figs. 2m; 3g; 4j; 6e,f).

Cypsela
Both ray and disc cypselas are small, up to 4 mm long, oblong-ovoid and densely covered with long, slender upwardly-directed twin-hairs (Figs. 2i; 4i; 6b,c). The twin-hairs are shorter at the base of the cypsela, very long towards the top, and each twin-hair comprises a double set of extremely slender cells whose apices may be slightly divergent forming a Y-shape, or one of the cells in the pair may be shorter and pressed against the side of the longer cell, making the hair single-celled at its very apex. The twin-hairs are straight, brittle and shiny, and can be reddish-brown, straw-coloured or almost pure white, depending on the species. The upper hairs extend above the top of the cypsela, over the base of the pappus, giving the appearance of an additional and structurally different pappus whorl. The fruits are longitudinally ribbed, but this is obscured by the twin hairs (Fig. 6c). The cypsela does not appreciably increase in size with maturity.

Pappus
An identical pappus is present on ray and disc florets. The pappus consists of two alternating series, each of ca. 10 stout, elongatesubulate, marginally and especially apically barbellate or subplumose elongate bristle-like scales that are up to 10 mm long (Figs. 3d,e; 4i; 6b,c). The pappus bristles are flattened and widest at the base, narrowing towards the apex. The marginal barbs are directed upwards at ca. 45 degrees to the bristle axis, and the barbs are stout; the barbs increase in density and length towards the bristle apex. The pappus bristles are shiny and pale straw-coloured, although in most species they are tinged an inky blue-black towards the tips (Fig. 3d,e), although this blue-black colour may not be present in all individuals. One of the series of bristles is shorter and narrower and with smaller, sparser barbs. This smaller whorl can be the inner or the outer (e.g. outer in H. mitis; inner in H. peduncularis).

Embryo sac development
Heterolepis has unusual bisporic embryo sac development, which was described by Ahlstrand (1992) after examination of H. aliena and H. peduncularis. The other genera of tribe Arctotideae have the usual Polygonum-type of embryo sac development (Ahlstrand, 1979a(Ahlstrand, , 1979b. Bisporic development is rare in the Asteraceae, apart from Heterolepis being documented only in a few members of the distantly-related subfamily Asteroideae (Ahlstrand, 1992).

Pollen
Pollen is a distinctive bright orange colour in fresh specimens ( their publication. In H. aliena, and presumably in other members of the genus, the pollen grains are oblate-spheroidal (round in equatorial view and round or sub-triangular in polar view), 25-30 μm in diameter and echinate. Pollen is echinate and tricolporate, the colpi being narrow with acute ends. The infratectum is 1.2-1.5 μm thick and comprises two distinct columellae layers separated by a single or multiple, spongy internal tectum. The outer layer is 0.8-1 μm thick and the inner 0.4-0.5 μm. The columellae of the inner layer are evenly distributed and not swollen at the base. The inside of the endexine is smooth. The grains are partially caveate, the cavea is of medium depth, spanned by thread-like columellae. The grains have about 70 unevenly-distributed spines that are 3-4 μm high and 4.5-5 μm in diameter at the base, with perforations throughout, including at the apex, a slightly swollen basal region, and with pendant columellae inside. The pollen surface is reticulate and slightly raised between the spines. Strother et al. (1996) investigated the karyology of H. aliena and reported a count of x = 6 (probably 2n = 12). A count of 2n = 20 is mentioned in Karis (2007) and x = 10 in the flora of Herman et al. (2000), but Funk and Karis (2009) consider these erroneous as they were unable to find any published study other than that of Strother et al. (1996). No authenticated records for other species have been traced.

Systematic position
The unique combination of morphological features characterising Heterolepis, and not found in any other Asteraceae taxon, comprises the following: deeply-lobed disc floret corollas, the 3 + 1 − lobed, female-fertile ray florets (true bilabiate rays have a 3 + 2 structure and are found with elongated ligules only in the Mutisioideae, while pseudobilabiate rays have a 4 + 1 lobe arrangement and occur only in the Barnadesioideae); the possession of staminodes in the rays; caudate anthers with relatively short, un-branched or barely-branched tails and a thin, soft, obtuse apical appendage; a biseriate pappus of barbellate or subplumose bristle-like scales; and the unusual stylar morphology. Heterolepis-type styles are found only in the tribe Arctotideae, but there are similarities with the styles of some members of Cichorioideae, Mutisioideae and Cardueae.
As a consequence of its unusual morphology, the systematic position of the genus has been subject to marked divergence of opinion. Linnaeus the younger, who published the first description in 1781, placed the type species in Oedera L. (currently in subfamily Asteroideae, tribe Gnaphalieae). Vahl (1791) considered the same taxon to be a member of Arnica L. (currently subfamily Asteroideae, Heliantheae alliance of tribes). Cassini (1821) was the first to note the morphological affinities between Heterolepis and Arctotideae. Lessing (1832) incorporated Heterolepis, together with all other Arctotideae, into an enlarged concept of Cynaroideae (the thistles; currently subfamily Carduoideae). Bentham (1873) Lessing (1832) and placed it within Cynareae. Merxmüller et al. (1977), in his treatment of Inuleae, considered that Heterolepis did not belong in that tribe, suggested instead that it be placed in Mutisieae.
The constantly-shifting phylogenetic position of Heterolepis has contributed to its taxonomic complexity, with the same species being placed unwittingly by different authors in what today would be recognised as different subfamilies. Currently, however, there is broad consensus, supported by molecular phylogenetic analysis (Funk and Chan, 2008), that the genus is related to tribe Arctotideae (subfamily Cichorioideae), confirming Cassini's (1821) assignment. However, the position of Heterolepis within Arctotideae has never been convincingly established: different morphological features appear to indicate an alliance with different subtribes, and some features are anomalous within Arctotideae, such as the bisporic embryo-sac development, the 3 + 1 lobed ray florets, and the pappus comprising robust capillary bristlelike scales.
Affinities with Arctotideae subtribe Arctotidinae are indicated by some aspects of the stylar morphology, the soft apical anther appendages, a very similar pollen shape and ultrastructure, and the fact that the plants are non-spiny. Also, the stems, peduncles and involucre in Arctotideae-Arctotidinae often bear unusual trichomes, similar to those in Heterolepis. Another shared feature is the dimorphic involucral bracts, with the outer bracts in both taxa being smaller, herbaceous and often glandular, while the inner bracts are larger with membraneous margins and obtuse, papery apices (this giving rise to Cassini's name Heterolepis). However, in Arctotidinae the outer bracts are entirely herbaceous and the inner bracts entirely papery; the transition between the different types of bract series is relatively abrupt. In Heterolepis there is, instead, a gradual transition in structure from herbaceous outermost to membraneous innermost bracts, with the middle bracts being morphologically intermediate.
Affinities with Arctotideae subtribe Gorteriinae (the spiny daisies) are indicated by the following: basal fusion of the involucral bracts (although the degree of fusion is much less in Heterolepis); by an alveolate receptacle (although the alveole margin projections are much shorter in Heterolepis); possession of milky sap (a feature not previously noted in Heterolepis but apparent at least in the type species, H. aliena [L.f.] Druce); caudate, barely-branched anther tails; the pattern of anther endothecial cell-wall thickening (which is similar to some members of the Berkheya Ehrh. clade of Gorteriinae, but markedly different from Arctotidinae, in which the endothecial thickenings are consistently radial; Funk and Karis, 2009). In addition, Heterolepis shares with many members of the Gorteriinae (including both species of Didelta L'Hér., but also species from other genera) the feature of ray florets bearing staminodes. Although Didelta in the Gorteriinae was reported by Robinson and Bretell (1973) to possess pappus bristles, Didelta pappus elements are spinescent and quite unlike those of Heterolepis. The chromosome number of x = 6 (for H. aliena; Strother et al.1996) has been recorded within both Gorteriinae and Arctotidinae, although counts in the tribe vary. Gorteriinae has records of 2n = 10, 12, 14 and 16 while most Arctotidinae have 2n = 18 with variation in this subtribe (of 2n = 10, 12, 18 and even higher) found only within the genus Haplocarpha Less (Karis, 2007). The ancestral number for the tribe is postulated to be x = 9, making Heterolepis unusual within the tribe (Funk and Karis, 2009).
Within Arctotideae, Cassini (1821) considered Heterolepis to be closer to subtribe Arctotidinae, due to style characteristics, but the possession of staminodes in the ray florets led Norlindh (1977) to place Heterolepis in subtribe Gorteriinae. DNA-based studies have been unable to resolve the issue, possibly due to a lack of comprehensive taxon sampling but also due to lack of sufficient information in the molecular markers sampled. As a result, Funk and Chan (2009)  Nomenclatural notes: Heterolepis Cass. (Cassini, 1820) was formally conserved over Heteromorpha Cass. (Cassini, 1817) by Rickett and Stafleu (1960 Illustration: Fig. 2. Habit: compact, sparsely-to well-branched shrublet forming a low, broad bush, to about 1.2 m (but usually 0.30-0.70 m) high. Stems: young stems soft, herbaceous, longitudinally striate, white-tomentose but not glandular; white-woolly tomentum of young stems continuous onto leaf buds and abaxial surfaces of mature leaves. Older stems woody, to about 1.0 cm in diameter, leafless, with smooth greyishbrown bark marked with leaf-scars. Leaves: densely or sparsely arranged around stem at branch ends, imbricate, erect, linear-lanceolate, 15-50 × 1.5-3.0 mm, ± equal in length along stem, sessile, not narrowing towards base, apically acute with a small mucro, leaf lamina somewhat thickened and leathery; margins strongly revolute, folded back over the abaxial surface which is thus largely obscured except for a small central portion, margins entire or with small, widely-spaced, acute mucro-like teeth; leaf adaxial surface dark green, glabrescent with slightly indented midvein; abaxial surface densely whitetomentose with midvein thickened, prominent, green and glabrescent in contrast to the white-tomentose abaxial leaf surface. Peduncle: 10-40 mm or rarely up to 70 mm long, increasing in length at floral maturity, sometimes bearing one or two small leaflike bracteoles; reddishbrown, faintly striate, not woolly or only sparsely so, and bearing a covering of trichomes (type A) that is most densely spaced at top of the peduncle.
Diagnostic characters: Heterolepis aliena is the commonest and most widespread member of the genus, and also the most variable. It is generally distinguishable from all other species by its much larger and showier heads, with a greater number of florets. The usual H. aliena head bears roughly double the number of both rays and discs of H. mitis and H. peduncularis; however, some plants have smaller heads with fewer rays. The leaves are generally stouter than those of the other species, and the peduncles of H. aliena are almost always much shorter than those of either H. peduncularis or H. anomala. The presence of milky-white sap has been noted in H. aliena, but this feature, observable only in fresh specimens, has not been investigated in the other species.
Flowering time: recorded in flower mostly between October and February, with peak flowering in November, December and January (Fig. S1). Most of the specimens flowering in other months come from localities growing very close to the sea in the Hangklip-Betty's Bay region of the south-western Cape.
Distribution: Heterolepis aliena is restricted to the western half of the CFR (Fig. 1), where it is found mainly in mountainous regions. There are several outlying populations further to the east in the sandstone mountains of the Little Karoo (Anysberg and Groot Swartberg ranges near Ladismith, and Witteberg near Matjiesfontein). The single record from the Kamiesberg in the Northern Cape is doubtful (see Fig. 1).
Habitat and ecology: Heterolepis aliena is recorded from rocky sites on Table Mountain Sandstone, usually in fire-protected sites, rooting amongst rocks or on cliff faces. We would classify the vegetation type to which it is endemic as Arid Fynbos, since the plant occurs in the more arid microsites (e.g. north-facing slopes) and at the arid margins of the fynbos on sandstone rocks. Although some collectors record cliff sites as being in shade for part of the day, this species generally grows in full sun. The following notes have been made about fire ecology: "Nine months after burning" (Kruger 139); "In 20 year-old vegetation" (Taylor 4629); "Sprouting in firebreak" (Kruger 1138); "A reseeding shrublet, in 6-yr old restioid veld" (Viviers 738); "Fynbos vegetation burnt 19 months ago" (Kruger 879); "Spruit na brand, groei in elk geval in plekke wat moeilik brand" (van der Merwe 24-37); and "In rock crevices, resprouting after fire (of one year previously)" (Williams 3398). From these comments, and from the flowering-time distribution with particular peaks in the midsummer months it can be concluded that, although the species may resprout after some fire damage, it does not necessarily have a resprouting fire-survival strategy. Instead, it grows in rocky, fire-protected sites. There is no strong evidence of resprouting on any of the specimens except for the fact that the living stems are generally small, perhaps indicating only a single year's growth; one specimen, Snijman 1338 (NBG) includes a portion of a woody rootstock attached to the above-ground stem. Quite possibly the main stems are protected from fire in rock crevices, while the shorter-lived flowering stems grow out from this protection to bear the flowers.
Etymology: the species epithet 'aliena' was provided by Linnaeus filius for the basionym, Oedera aliena, perhaps referring to the incongruity of this species in the genus Oedera.
Red-List status: Least Concern (Foden and Potter, 2005a). Nomenclatural notes: The name Heterolepis decipiens is not linked to any known specimen, but appears to represent a new combination, although neither of the two basionyms listed by Cassini (1821) and Lessing (1832) is reflected in the name. Confusion starts with Cassini (1817), who published a new genus, Heteromorpha, for the taxon described by Vahl (1791) as Arnica inuloides. Cassini recognised that this species did not belong in Arnica and considered it to have greater affinity with the tribe Arctotideae. However, he did not formalise the new combination in Heteromorpha. A few years later (Cassini, 1820), Cassini decided to change the name Heteromorpha to Heterolepis because he considered the former too adjectival. In this publication, he considered the names Arnica inuloides Vahl and Oedera aliena L.f. to apply to a single species, which he classified in Heterolepis, but again he did not make the new combination for either name. The species epithet 'decipiens' is mentioned first in Cassini's (1821) treatment of Heterolepis, where he wrote (pp. 120-121) "Hétérolèpe trompeur: Heterolepis decipiens, H. Cass., Bulletin des sciences, Février 1820; Heteromorpha, H. Cass., Bulletin des sciences, Janvier 1817" and then listed Arnica inuloides Vahl and Oedera aliena L.f., seemingly as synonyms. Thus he appears to be citing an earlier publication (Bulletin des sciences, February 1820) for the name Heterolepis decipiens. However, we have not been able to discover any publication referring to the name prior to the 1821 publication cited above. In particular, Cassini (1820), which is presumed to be the article referenced by "Bulletin des sciences, Février 1820", makes no mention of the binomial "Heterolepis decipiens". In his writings between 1817 and 1821, Cassini refers all mention of Heterolepis and Heteromorpha to Arnica inuloides Vahl. and/or Oedera aliena L.f., merely placing those taxa in his new genus. Cassini's (1821: p. 123) statement "L'épithète de trompeur, decipiens, que nous donnons a l'hétérolèpe, est bien justifiée par toutes les remarques qu'on vient de lire", suggests his intention to publish a new binomial. If this interpretation is accepted, the name Heterolepis decipiens is nomenclaturally both illegitimate and superfluous, because Cassini (1821) simultaneously cited two validly published earlier names, Arnica inuloides Vahl and Oedera aliena L.f. The valid basionym for the species would therefore be the earliest published name, i.e. Oedera aliena.
Lessing (1832) accepted Heterolepis decipiens as a validly published binomial, citing both Oedera aliena L.f. and Arnica inuloides Vahl. as synonyms, as well as Thunberg's Leysera arctotoides. The combination of the earliest available name, Oedera aliena, in Heterolepis was formally published by Druce (1917). Rickett and Stafleu (1960) noted that the combination of Arnica inuloides under the generic name Heterolepis was never made, but stated that in their view, proposing this combination was not neccessary "because it would be superfluous in view of the generally accepted taxonomic synonymy with Heterolepis aliena" (i.e., the basionym Oedera aliena has nomenclatural priority over Arnica inuloides). As noted previously by Flann et al. (2010), in Appendix IIIA of the International Code of Nomenclature for algae, plants and fungi (McNeill et al., 2012), the type for Heterolepis is incorrectly listed as Heterolepis decipiens Cass. As noted above, Cassini (1821) cited both Arnica inuloides Vahl and Oedera aliena L.f. in conjunction with the name H. decipiens, therefore the generitype is Heterolepis aliena (L.f.) Druce, based on the earliest available name, Oedera aliena L.f.
Minurothamnus phagnaloides DC. was mistakenly synonymised with H. aliena by Merxmüller (1950). Examination of a scan of the type specimen from G-DC indicates that this specimen is in fact H. peduncularis DC., so this name is treated under that species.
Leysera arctotoides Thunb. is a name originally published in 1800. There are two sheets named 'Leysera arctotoides' in Thunberg's collection housed at Uppsala. The sheet 'Leysera arctotoides. 1.' (UPS-THUNB 20073) has been annotated with subsequent names (Oedera aliena L.fil. nec Thunberg; Arnica inuloides Vahl! and Heterolepis decipiens Cass.) and is a specimen of Heterolepis aliena. The sheet 'Leysera arctotoides. 2.' (UPS-THUNB 20074) has no further annotations and comprises two twigs. That on the right and an additional capitulum are of Heterolepis aliena, but the leftmost twig has extremely long peduncles and the leaves are thin, weak and decrease in length up the shoot, so it is more likely to be a specimen of H. peduncularis. Unlike the 20073 sheet, ray florets are not easily discernable in the second sheet. The unmixed collection, sheet UPS-THUNB 20073, is here designated the lectotype.
Peduncle: capitula sessile, or peduncle 1-2 mm long, glandular with trichome type A, trichomes on peduncle larger than those on the adjacent stem. Capitula: radiate, in pressed specimens 22-30 mm in diameter including expanded rays, with~44 disc and~2-16 ray florets (note: this number based on only two dissected specimens). Involucre: 7-12 mm wide, fleshy portion sparsely dotted with very small pale glands; outermost bracts only slightly smaller than middle or inner, narrowly deltoid-lanceolate, free portion 5-7 × 0.8-1.0 mm, apically acute; inner bracts with free portion 8-10 × 2.0-4.0 mm. Involucre becoming dark brown when old. Receptacle: alveoles pentamerous, margins with short toothlike projections 0.5 mm long, a tooth at each of the five corners of each alveole. Ray florets: corolla deep yellow, corolla tube glabrous or with a few scattered glands, ± 4.5 mm long; ray lamina 3.0-4.0 × 7.5-9.0 mm, abaxial surface of lamina lobes apically glanddotted with small, rounded trichomes. Staminodes with filaments; staminode tails rounded and incurved, apical appendages obtuse. Cypsela and pappus as in disc florets. Disc florets: deep yellow, tube 6.0 mm long; corolla lobes 2.5-3.0 mm long, becoming strongly recurved after anthesis, apically dotted with globose multicellular trichomes. Style extending ± 5 mm beyond corolla tube at maturity, becoming densely papillate at a slight thickening~2.0-3.0 mm below apex, thickening without a longer tuft of sweeping hairs. Stigmatic branches short, narrowing slightly to rounded apices. Apical anther appendages about 1.0 mm long, obtuse with short mucro-like structure, central vein with dark yellow pigment near apex. Anther tails about 0.07 mm long, broadly acute, slightly curved inwards. Pappus: of approximately 20 robust, brittle, strap-shaped cartilaginous bristle-like scales, apically tinged strongly blue-black, colour fading to base which is straw-coloured and shiny; flattened and widened near base (to about 0.13 mm wide), tapering towards apex. Inner series of ±10 bristles, 8-9 mm long, slightly longer than the full length of the corolla, narrowing towards the apex where the barbs become longer and increasingly dense. Outer series of ± 10 bristles, slightly narrower and much shorter than inner series, ± 3 mm long, apically more sparsely barbellate than inner bristles. Pappus elements free. Cypsela: twinhairs bright white, providing a strong colour contrast to the pappus bristles.
Diagnostic characters: Heterolepis mitis is the most morphologically distinct member of the genus, due to its small size, dark green, glabrous and slender leaves, small, sessile capitula partly enveloped by the upper leaves, and habit of growing in the crevices of sandstone rocks. The leaves, stems and involucral bracts are markedly less glandularscabrid than all other species in the genus, although small, somewhat sunken glands are present. Probably the most distinctive feature of Heterolepis mitis is its glabrous foliage, giving the plant a dark-green appearance in contrast to the grey-green or whitish appearance of the other species. Heterolepis mitis also has the easternmost distribution. Several collections note the fact that the plants are 'aromatic', and rehydrated material is exceptionally pungent-smelling. The stems and leaves frequently become viscid on drying, as if covered with a clear varnish layer, a feature which has not been observed on other species of Heterolepis.
Flowering time: recorded in flower in January, April, August, October and December (Fig. S1), despite the small number of records. Possibly the plant flowers continuously throughout the year, or sporadically, depending on rainfall, and plants may bear only a few capitula at any one time.
Distribution: (Fig. 1). This species is known from only a few collections, all in the same quarter-degree grid square, in the southern and western foothills of the Suurberg and Klein Winterhoek ranges near Kirkwood in the Eastern Cape.
Habitat and ecology: Heterolepis mitis grows only on rock faces, rooting in crevices in rocks of the Witteberg Group sandstones. The rock-crevice habit is otherwise found only in some individuals of H. aliena.
Habit: sparsely-branched, twiggy shrublet 0.20-1.0 m high. Stems: younger stems slender and pale with a dense white-woolly indumentum; older stems with thin dark bark; longitudinally striate, eglandular. Leaves: borne mainly on the lower stems, loosely imbricate, erect or erect-spreading, linear, lower leaves 20-60 × 1.5-2.0 mm, leaves decreasing in length acropetally, upper leaves b10 mm long; sessile, obscurely auricled at base, apex bluntly acute, somewhat thickened and leathery, margins strongly revolute and covering the edges of the abaxial surface, with small sparse marginal teeth or sometimes entire, adaxial surface grey-green, glabrous to glabrescent, abaxial surface densely white-tomentose except on midrib which is prominent and green. Peduncle: 40-190 mm long when mature, elongating rapidly on floral maturation, bearing one or two minute leaflike bracteoles; not woolly or only sparsely so; reddish-brown, faintly striate and densely invested with very fine to stout stalked trichomes (type A). Capitula: radiate, occasionally discoid, in pressed specimens mature heads are 12-35 mm in diameter including expanded rays, containing ± 25-42 discs and ± 6-12 rays (based on dissection of heads from two specimens). Involucre: 8-15 mm across, green, fleshy portion of bracts glabrous or sparsely white-woolly, as well as densely glandular with trichomes of type A. Outermost bracts narrowly deltoid-lanceolate, free portion 4-6 × 1.0-1.2 mm, innermost bracts with free portion 14-18 × 2.5-5 mm.
Receptacle: alveole margin projections irregular and slightly thickened. Ray florets: corolla golden yellow, tube with stalked trichomes of type B, lamina 3-4 × 8-12 mm. Point at which style sweeping-hair covering begins is unmarked by any swelling or hair tuft. Style branches short, broadly acute. Sterile anthers reduced, with no or very short filaments. Cypsela and pappus as in disc florets. Disc florets: golden yellow, 10 mm long, tube sparsely covered in elongate, multicellular clavatetipped trichomes (type B); corolla lobes broadly acute, 2-3 mm in length, strongly recurved after anthesis, abaxially invested with bluntended multicellular trichomes (type C) near apex. Style exserted ± 6 mm beyond corolla tube; point at which sweeping-hair covering begins marked by a ring of longer hairs. Style branches short, broadly acute. Anther tube narrow, apical anther appendages thin, flat, short, obtuse, with a central patch of pigmented cells; anther bases sagittate with elongate, rounded tails.
Pappus: of approximately 25-35 straw-coloured or black-tinged bristle-like scales, inner series coming to about halfway up the corolla lobes, outer series shorter than this, to between half and three-quarters of the length of the inner. Pappus scales fused at base, individual bristles conspicuously widened near base (to about 0.5 mm wide), tapering towards apex. Bristle margins and apex plumose, plumes upwardlydirected. Cypsela: twin-hairs straw-coloured or reddish-brown.
Diagnostic characters: Heterolepis peduncularis is most easily confused with the discoid-headed H. anomala. However, H. anomala has thicker leaves that do not noticeably decrease in length upwards on the stem (Fig. 5), and also has a very narrow distribution range only on the northern slopes of the Langeberg in the Garcia's Pass area. Heterolepis peduncularis is distinguished from the remaining members of the genus by its long peduncles, usually 100 mm or longer, and by its lax, slender leaves that decrease in length moving acropetally up the stem (Fig. 5). It is a plant with a very 'straggly' appearance, which is probably exacerbated by grazing. Several collectors noted an aromatic or sharp odour associated with this species, with one collector classifying the odour as lanolin, and another as apples. One specimen of (le Roux 1452, collected between Worcester and Robertson) has discoid heads. However, in all other characteristics, this is clearly H. peduncularis. One mutant specimen, Bohnen 9046 from Springfontein near Elim, has true bilabiate ray florets and a trifid style. Three-lobed style branches are commonly observed in Dymondia Compton (Arctotideae subtribe Arctotidinae).
Flowering time: Heterolepis peduncularis flowers mainly in early summer (Fig. S1), with the peak flowering period in October and November, tailing off in December. However, flowering specimens have been collected in several other months (January, February, June, July and September).
Distribution: the species occurs almost entirely on the Southern Cape coastal platform south of the east-west trending Cape Fold ranges (Langeberg and Riviersonderend mountains), but there are collections from between Worcester and Touwsriver, and from the Warmwaterberg area in the Little Karoo (Fig. 1). The species has not been collected west of the 19 degree line of longitude. The easternmost collection is from the Mossel Bay region, just east of the Gouritz River bridge.
Habitat and ecology: Heterolepis peduncularis grows in soil in open scrubland in South Coast renosterveld vegetation, or possibly in the renosterveld-fynbos transition. Recorded substrates are frequently a mixture of shales and sandstone, for example, collectors note the substrate type to be shale overlain by Table Mountain Sandstone gravel, or silcrete. Renosterveld vegetation is frequently noted on herbarium labels, as is rocky, loamy soil and occurrence on flats or flat areas. In terms of its fire ecology, the following collector notes are relevant: "Veld 7 years old" (Helme 5368); "Burnt areas on slopes: frequent" (Levyns 6196); "Resprouting shrub in veld burnt recently-approx. several months to one year previously?" (Bergh 2043); "200 ha patch of N20-year old (renoster)veld" (Helme 1898); "resprouts after fires (?)" (Burgers 1641A). From these notes it seems that post-fire resprouting may be present in H. peduncularis, although it is not known to what extent this is obligatory.
Etymology: the species epithet 'peduncularis' likely refers to the long peduncle which, together with the smaller capitula containing fewer florets, distinguishes this species from H. aliena.
Red-List status: Least Concern (Foden and Potter, 2005b) Nomenclatural notes: In the protologue for Heterolepis peduncularis, De Candolle cites two specimens: Burchell 6828 and Ecklon 'in Zwellendam' (this is probably Ecklon 3300, also ticketed 'Zeyher 3300' in some herbaria). Both specimens are in Geneva. The Burchell specimen is here designated the lectotype.
The name Minurothamnus phagnaloides DC. was published by De Candolle (1838b) in a supplement (Mantissa Compositarum) to his treatment of the Asteraceae in the Prodromus systematis naturalis regni vegetabilis. De Candolle clearly considered his new genus to be a member of the tribe Inuleae (as it is defined today), because he listed it between Pegolettia and Geigeria, and also stated 'Videtur Inulea. Affinis Cypselodontiae et Pegolettiae'. Possibly for this reason, De Candolle (and subsequent authors) did not recognise that Minurothamnus phagnaloides is actually a species of Heterolepis. Only in the 20th Century did Merxmüller (1950) synonymise the name with Heterolepis aliena (L.f.) Druce. However, Merxmüller based this only on the description as he was unable to examine the original material in G-DC. One of us examined a digital image (on microfiche at BOL) of the specimen Ecklon 274, which is the sole sheet in G-DC annotated by De Candolle with the name Minurothamnus phagnaloides. The specimen is clearly conspecific with H. peduncularis and not H. aliena. The name Heterolepis peduncularis has nomenclatural priority and therefore Minurothamnus phagnaloides is here placed in synonymy with that name.
Additional specimens examined (41 collections from BOL, G, GRA, K, Illustration: Figs. 5 & 6. Habit: sparsely-branched, compact shrublet generally to about 0.3 m high. Stems: young stems densely white-woolly, older stems sparsely white-woolly with thin dark bark; longitudinally striate, eglandular. Leaves: most dense at the lower ends of the branches, densely imbricate, erect, linear, terete, 8-18 × 0.9-1.5 mm, not becoming shorter acropetally, sessile, apex shortly mucronate, thickened and leathery, margins strongly revolute and very sparsely dentate with only (0-) 1-3 tubercle-like teeth per leaf, adaxially sparsely white-woolly when young, becoming glabrous, mid-rib visible on adaxial surface, abaxial leaf surface densely white-tomentose except on green midrib, but this surface mostly obscured by the revolute margins. Peduncle: 25-110 mm long when mature, elongating rapidly on floral maturation, bearing one or two leaflike bracteoles, not woolly or only sparsely so, reddish-brown, faintly striate and densely invested with very fine to stout trichomes of type A.
Diagnostic characters: Heterolepis anomala is distinguished from all other species by its discoid heads. It is, however, most similar to H. peduncularis, and specimens in herbaria may be filed with the latter species. The black colour characteristic of the pappus bristles in H. aliena and H. mitis, and some specimens of H. peduncularis, was not observed in any specimens of H. anomala, which has instead distincly pale pappus bristles and corolla lobes. The style-branch apices are unique in H. anomala, being truncate and slightly cleft, whereas in all other species the style-branch apices are rounded to broadly acute.
Flowering time: the five collections of this species are mostly from different months: three in late summer / early winter (March and April) and two in early to mid-summer (October and December); Fig. S1.
Distribution: Heterolepis anomala is currently known only from the farms Muiskraal and Fisantefontein, on the northern foothills of the Langeberg near Garcia's Pass (Fig. 1).
Habitat and ecology: Collectors note Heterolepis anomala growing in arid fynbos on well-drained, often rocky Table Mountain Sandstonederived soil. In one instance (Vlok 2780) the collector noted 'resprouting after fire' but for another collection (McDonald 2091) it was noted that the plant was 'growing in undisturbed, old veld'.
Etymology: the species epithet 'anomala' denotes the discoid heads which are unique in the genus.
Red-List status: Vulnerable, due to potential threats from alien invasive plants and habitat degradation linked to heavy livestock grazing after burning (von Staden and Raimondo, 2014).