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Phytotaxa 329 (1): 051–068
http://www.mapress.com/j/pt/
Copyright © 2017 Magnolia Press Article PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
Accepted by Carlos Lehnebach: 30 Oct. 2017; published: 24 Nov. 2017
https://doi.org/10.11646/phytotaxa.329.1.3
51
A taxonomic revision of the western South American genus Presliophytum
(Loasaceae)
RAFAEL ACUÑA1,2* & MAXIMILIAN WEIGEND1
1Universität Bonn, Nees-Institut für Biodiversität der Pflanzen, Meckenheimer Allee 170, 53115 Bonn, Germany.
E-mail: rafael.asurbanipal@gmail.com
2Universidad de Costa Rica, Escuela de Biología, Apdo. Postal: 11501-2060 San Pedro de Mondes de Oca, Costa Rica
Abstract
Presliophytum is a small genus of five species endemic to arid western South America, including coastal Peru and the Ata-
cama Desert. The type species, Presliophytum incanum, was originally described in Loasa, but recognized as highly distinc-
tive and placed into a monotypic section in the late 19th century. Together with Loasa heucheraefolia and a newly described
species, it was placed into the genus Presliophytum in 1997. Subsequent molecular studies confirmed the monophyly of the
genus and indicated a close relationship to two Chilean species, traditionally placed in Loasa series Malesherbioideae, a
placement formalized in 2017 by providing the necessary new combinations. However, a detailed revision and description
of the taxon has not been provided and the present study aims at filling this gap. We provide data on the morphology and
micromorphology, distribution and ecology of the five species, as well as a key for all the species. Presliphytum incanum
is the most common and widespread species, but also morphologically the most variable. There are differences in leaf and
flower morphology between northern and southern populations, but these are difficult to discern in herbarium specimens.
The species is therefore here maintained in the broader sense, since at present it seems impossible to clearly differentiate
two morphologically discrete entities.
Key words: Cornales, endangered species, endemic species, floral morphology and anatomy, systematic relationships, tri-
chomes
Introduction
Presliophytum (Urb. & Gilg) Weigend (2006: 467) is a small genus composed by five species: P. arequipense Weigend
(2006: 467), P. heucheraefolium (Killip) Weigend (2006: 467), P. incanum (Graham) Weigend (2006: 467), P.
malesherbioides (Phil.) R.H. Acuña & Weigend in Acuña et al. (2017: 373) and P. sessiliflorum (Phil.) R.H. Acuña &
Weigend in Acuña et al. (2017: 373). The first three species are shrubs endemic to the Pacific slope of Peru and were
placed in Presliophytum based on morphological data (Weigend 1997, 2006). Molecular data published over the last
two decades clarified the phylogeny of Loasaceae subfamily Loasoideae and confirmed the assumption of Weigend
(1997) that two herbaceous northern Chilean/Argentinean species, Loasa malesherbioides Philippi (1864:74) and L.
sessiliflora Philippi (1893:12), belong to the same clade (Weigend 2004, Weigend et al. 2004b, Hufford et al. 2005,
Acuña et al. 2017).
Presliophytum incanum, the type species of the genus, was collected by European botanists at least as early as
1778 (Ruiz & Pavón 1959) when the Botanical Expedition to the Viceroyalty of Peru lead by Hipólito Ruiz and José
Pavón (accompanied by Joseph Dombey) collected material in the Obrajillo area (Departmento de Lima, Lang 1985).
The species was published as Loasa incana Graham (1830: 169) several decades later from material of the same
area.
During the last decade of the 19th century, Loasa section Presliophytum Urb. & Gilg in Gilg (1894: 118), including
only Loasa incana, and Loasa section Euloasa Urb. & Gilg in Gilg (1894: 115) series Malesherbioideae Urb. & Gilg
in Gilg (1894: 116, 118), including Loasa malesherbioides and L. longiseta Philippi (1865: 347), were described.
Weigend (1997) investigated the genus limits in Loasaceae subfam. Loasoidaeae and segregated section Presliophytum
as a separate genus, including three species: Presliophytum incanum, newly described Presliophytum arequipense,
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52 • Phytotaxa 329 (1) © 2017 Magnolia Press
and renamed Presliophytum heucheraefolium based on Loasa heucheraefolia Killip (1928: 90). Weigend (1997) also
indicated that series Malesherbioideae probably belonged to the same lineage and should be placed in Presliophytum,
however, this was not formalized by renaming these species. No additional nomenclatural changes were done since
then, until Acuña et al. (2017) transferred Loasa malesherbioides and L. sessiliflora into Presliophytum, establishing
the genus as currently understood.
The relationships of Presliophytum to other clades in Loasaceae were obscure until recently. As pointed out by
Weigend (1997; 2004), morphologically and ecologically, there are several similarities between Presliophytum and
the northern Chilean genus Huidobria Gay (1847: 438–439). Both genera include deserticolous shrubs with a strong,
fleshy tap-root, alternate phyllotaxis, complex asymmetrical dichasial inflorescences with extensive concaulescence
and recaulescence, erect flowers, white to pale yellow corollas and floral scales, and thousands of minute seeds per
fruit (Weigend 1997, 2004). However, based on the molecular data now available (Acuña et al. 2017), all these traits
are apparently either plesiomorphic or the result of convergent evolution in similar environments. More detailed
morphological analyses reveal a series of profound differences between both of these groups of plants: Huidobria lacks
the stinging hairs (setae) found in Presliophytum. Also, the floral scales in Presliophytum are typical of the bulk of
Loasoideae, with the staminodial complexes consisting of three outer staminodes fused into a scale and two free, inner
staminodes (Urban & Gilg 1900, Grau 1997, Weigend 1997). Conversely, Huidobria has staminodial complexes with
the scales variably formed by 4–7 incompletely fused staminodia and 3–5 inner free staminodia (Grau 1997, Hufford
2003). The dust seeds of Huidobria are oblong with sparse testa reticulations or striations, while those of shrubby
Presliophytum are ovoid with a densely reticulate-foveate testa (Grau 1997, Weigend 1997).
Molecular data indicate a distant relationship between Huidobria and Presliophytum, and a paraphyly of Huidobria
(Moody et al. 2001, Weigend et al. 2004b, Hufford et al. 2005, Acuña et al. 2017). Both Hufford et al. (2005) and
Acuña et al. (2017) retrieved Presliophytum as sister of the South Andean Loasas clade, whereas H. fruticosa Philippi
(1855: 219) is retrieved as the basal-most branch of subfamily Loasoideae and H. chilensis Gay (1847: 440) as sister
of Klaprothieae+Kissenia R.Br. ex Endlicher (1842: 76).
According to the latest phylogenetic evidence Presliophytum malesherbioides, from Chile and western Argentina
is the basal-most branching species of the genus (Acuña et al. 2017). This taxon differs from the rest in habit (annual
or subperennial herbs vs. perennial subshrubs or shrubs), development of the root system (thin and simple vs thickened
and branched), leaf morphology (margins subentire to shallowly lobate vs margins regularly lobate), chromatic
contrast between the nectar scales and the corolla (conspicuous vs inconspicuous), and morphology of the nectar scale
(dorsal threads short and clavate vs dorsal threads long and filiform; apical wings well developed vs apical wings
rudimentary). Presliophytum sessiliflorum from northern Chile is sister to P. arequipense, P. heucheraefolium and
P. incanum (the Peruvian shrubby species). In habit it is intermediate between P. malesherbioides and the Peruvian
taxa, being a perennial subshrub with thickened underground structures. The external morphology of the leaves (with
regularly lobate blades) and flowers (broad sepals, white nectar scales with filiform dorsal threads and rudimentary
apical wings) is closer to the shrubby Peruvian species, while in seed morphology (with conspicuous transversal
constrictions and undulate periclinal walls) it appears closer to P. malesherbioides. Its small 2-placentae, 4-seeded
fruit is very characteristic (Grau 1997). The three shrubby Peruvian taxa are more closely related to each other than
to any other extant taxon, and form a well-supported clade based both on molecular evidence (Acuña et al 2017) and
morphology: all are shrubs to about 1.5 m tall with woody aboveground and underground structures, having strongly
metatopic inflorescences, and almost identical floral scales, globose fruits and diminutive seeds.
The goal of this study is to present a revision of the genus Presliophytum as currently understood, based on macro-
and micro-morphological studies of living plants both from the wild and cultivation, as well as herbarium specimens.
Materials and methods
Field studies were carried out in Peru between 1997–2014. Specimens were prepared in the field following standard
techniques and voucher sets were deposited in Peruvian herbaria (USM, HUSA, HUT), and in Berlin (B), Bonn
(BONN) and Munich (M). In addition, specimens or photographs from the following herbaria were revised: BAB, BM,
BONN, CONC, E, F, G, HUSA, K, L, MA, P, SGO, SI and US. All of the taxa recognized here, except Presliophytum
sessiliflorum, have been brought into cultivation in the glasshouses at the Institut für Biologie –Morphologie und
Systematik der Pflanzen, Freie Universität Berlin and Botanische Gärten der Universität Bonn, Germany.
Measurements of most structures were taken from herbarium specimens. Diagnostic or distinctive characters
were identified and are indicated in bold for each species description. The specimens were georeferenced for mapping,
REVISION OF PRESLIOPHYTUM (LOASACEAE) Phytotaxa 329 (1) © 2017 Magnolia Press • 53
whenever possible. When the geographical coordinates were not included in the specimen label information, the
original collectors’ published itineraries were studied, when available, and the collection localities searched in the
free access GeoNames (http://www.geonames.org) or directly in Google Earth Pro ver. 7.1.7.2606 (Google Inc. 2016).
Each specimen was plotted using the maps package (Brownrigg 2017) for the R software (R Core team 2014). The
conservation status assessments are based on the Red List Criteria by the IUCN (2001).
To analyze the microstructure details of foliar surfaces and seeds we used fresh material from cultivated plants
of five different accessions of Presliophytum from Peru. Dry material collected in Chile was employed for the two
remaining species. Fresh material was studied with cryo scanning electron microscopy in order to avoid drying
artifacts. SEM studies were carried out following the methods of Ensikat & Weigend (2013). Both fresh and dry
material (including seeds) were sputter coated lightly with Au or Pd for about 20 seconds in a SCD040 (Balzers Union,
Liechtenstein) in order to increase the electrical conductivity.
Results
Morphology
Seedlings:—The germination, as in other Loasoids is epigeal (Weigend 1997). The cotyledons are 1–2 mm long,
ovate, subcircular or oblong and develop an emarginate apex with a terminal hydatode. Veins are inconspicuous. The
second pair of leaves produced shows poorly developed toothed margins. Successive leaves become progressively
more deeply dissected. During very early stages of development, the leaf morphology of all the species is quite similar,
but clear differentiation is evident after few weeks.
FIGURE 1. Vegetative morphology of Presliophytum. A. Habit and habitat of shrubby Presliophytum incanum (Quinistaquillas, Moquegua,
Peru, not vouchered). The three species of Peruvian Presliophytum have similar habits. B. Habit and habitat of subshrubby Presliophytum
sessiliflorum (Quebrada La Chimba, Antofagasta, Chile, Luebert et al. 3405, BONN; photo courtesy of F. Luebert). C. Habit and habitat of
herbaceous Presliophytum malesherbioides (Juntas del Toro, Coquimbo, Chile, not vouchered; photo courtesy of M. Eyzaguirre). Mature
specimens of this species range from unbranched annuals to densely branched subperennial herbs as the one illustrated. D. Mature leaf
of Presliophytum arequipense (cultivated, seeds collected near Mollendo, Arequipa, Peru, Ortiz et al. 121, BONN). E. Mature leaf of
Presliophytum heucheraefolium, (cultivated, seeds collected near Río Cacchán, Áncash, Peru, Weigend et al. 7691C, BONN). F. Mature
leaf of Presliophytum incanum (cultivated, seeds collected near Ullpan, Áncash, Peru, Weigend & Hilger 8912C, BONN). G. Mature leaf
of Presliophytum incanum (cultivated, seeds collected near Omate, Moquegua, Peru, Ackermann & Cáceres 674, BONN). Scale bars 15
mm. Photos by R. Acuña and M. Weigend, unless otherwise credited.
ACUÑA & WEIGEND
54 • Phytotaxa 329 (1) © 2017 Magnolia Press
Adult habit:—Mature plants are densely branched from the base (Figs. 1A–C). Life form is variable and strongly
dependent on moisture availability. Plants range from woody shrubs up to 1.5 m tall (Fig. 1A) to low subshrubs up to
50 cm tall with succulent, persistent underground organs (Fig. 1B) or annual to subperennial herbs less than 30 cm tall
(Fig. 1C). Wood anatomy of Presliophytum incanum was described by Carlquist (1984) as similar to that of Kissenia
capensis Endlicher (1842: 76) and Nasa picta (Hook.) Molinari (2015: 68), differing from them in the much smaller
multiseriate rays and absence of axial parenchyma. All taxa have a dominant taproot.
FIGURE 2. Microstructure and trichome morphology of Presliophytum. A. Adaxial foliar surface of a mature leaf of Presliophytum
arequipense (Ortiz et al. 121, BONN). Presliophytum incanum has virtually identical indumentum. B. Abaxial foliar surface of a mature
leaf of Presliophytum arequipense (Ortiz et al. 121, BONN). Presliophytum incanum may have similar indumentum or mostly made
up by scabrid trichomes. C. Adaxial foliar surface of a mature leaf of Presliophytum heucheraefolium (Weigend et al. 7691C, BONN).
This species and Presliophytum sessiliflorum have abundant and relatively long uniseriate glandular hairs, on leaves and younger stems.
Presliophytum malesherbioides has similar but much shorter trichomes in some areas of the stem. D. Abaxial foliar surface of a mature
leaf of Presliophytum heucheraefolium (Weigend et al. 7691C, BONN). GL: Glochidiate trichome, GT: Uniseriate glandular trichome, SC:
Scabrid trichome, SS: Short smooth trichome. Scale bars A, B: 100 µm; C, D 200 µm.
Leaf morphology:—Phyllotaxis is opposite in the lower part and alternate in the upper part of the stem, probably the
plesiomorphic condition in Loasaceae (Weigend 1997). Leaves are petiolate (Figs. 1D–G), the frondose prophylls and
REVISION OF PRESLIOPHYTUM (LOASACEAE) Phytotaxa 329 (1) © 2017 Magnolia Press • 55
the leaves just below the inflorescences are often sessile or subsessile. Lamina is (narrowly) ovate in most species, but
reniform to subcircular in Presliophytum heucheraefolium (Fig. 1E). Leaf bases are cordate to truncate, more rarely
cuneate. Leaf margin is usually lobate or lobulated with 3–8 lobes on each side, usually only dentate to subentire in P.
malesherbioides.
Indumentum:—All species have stinging trichomes (setae). These are especially numerous in Presliophytum
malesherbioides and P. sessiliflorum, whereas the shrubby species develop relatively few stinging hairs. Stinging hairs
are particularly abundant on the ovary and younger portions of the stem. All the species have a ‘hoary’ appearance
because of the high density of scabrid and glochidiate trichomes on stem and leaves (Figs. 2A, B). Uniseriate glandular
trichomes are also common and particularly well developed in the leaves and young stems of P. heucheraefolium and
P. sessiliflorum (Figs. 2C, D). Most P. malesherboides plants have short and inconspicuous glandular trichomes on
the stems, but the leaves are mostly eglandular. In P. arequipense and P. incanum glandular trichomes are absent or
extremely rare (Fig. 2B).
Inflorescence morphology:—Inflorescences are complex dichasia, with alternate, foliose (sub-) sessile prophylls. In
Presliophytum malesherbioides and P. sessiliflorum the inflorescence branches are symmetrical, but in the shrubby
species one of the branches grows much more than the other and is hardly distinguishable from vegetative branches.
Each flower is subtended by two prophylls, the alternate phyllotaxis is the result of the conspicuous metatopia product
of recaulescence and concaulescence, a trait more developed in the shrubby taxa (whose flowers appear to be solitary:
cf. Weigend et al., 2004b: Figs. 6A vs 6C). Flowers are erect, less frequently horizontal to deflexed.
Flower morphology:—Flowers are epigynous, pentamerous and complete in all taxa (Figs. 3A–F). The sepals range
from ovate (Fig. 3A) to narrowly lanceolate or linear (Fig. 3E). Petals are usually spreading and white, sometimes
greenish white or cream-coloured (Figs. 3A–C, E–F). Some southern populations of Presliophytum incanum are quite
different in having half-spreading, yellowish petals (Fig. 3D). Petals are deeply cymbiform with a well-defined claw
and limb. Floral scales are usually the same color as the petals, except in P. malesherbioides, where they vary from
yellow to mostly white, but are always provided with some yellow or green markings (Fig. 3E). Scales in all species
have three dorsal threads (Fig. 3G).
There are two staminodes opposite to the interior of each nectar scale. The proximal portion is more or less
sigmoid and papillose, the terminal is filiform, extending well beyond the scale. There are 30 to ca. 150 fertile stamens
per flower. In most species the ovary is unilocular with 3–5 parietal, non accrescent-placentae with 5–1600 ovules
each. Presliophytum sessiliflorum differs in a bilocular ovary with two placentae, each with two ovules only.
The flowers of the shrubby taxa are visited by Lepidoptera, Hymenoptera, and Trochilidae. Presliophytum
malesherbioides has been collected with small Diptera on the stamens and petals (F. Luebert pers. comm.). Henning &
Weigend (2011) studied the thigmonastic stamen movement in P. heucheraefolium in detail.
Fruit morphology:—Fruits are erect, inferior, straight, xerochasious capsules, opening apically with 3–5 valves
(Weigend 2004, Weigend et al. 2004a). The fruits of Presliophytum sessiliflorum may be indehiscent, but detailed
observations are missing. Fruit shape varies from globose (almost as long as wide, Fig. 3H) to cylindrical and obconical
(longer than wide, Fig. 3I). The smallest fruits (5.0 × 3.0 mm not counting the sepals or trichomes) are found in P.
sessiliflorum meanwhile the largest (up to 28 × 15 mm) are those of some P. malesherbioides.
Seed morphology:—The Peruvian taxa have foveate-reticulate dust seeds, ca. 0.5 mm in length (Fig. 3J). Presliophytum
malesherbioides, especially, and P. sessiliflorum have conspicuous transversal constrictions (Figs. 3K, L), and very
similar seed testa sculpturing, with tetragonal cells and undulate periclinal wall surfaces. The seed set per fruit varies
between 4 in P. sessiliflorum, to >3000 in the shrubby species (Weigend et al. 2004a).
Distribution and habitat
Presliophytum is endemic to arid western South America (Fig. 4). It is mostly restricted to the Pacific slope, from
Departamento de Piura in northwestern Peru (P. incanum) to Región de Coquimbo in Chile (P. malesherbioides),
however it crosses the Andes onto the eastern slope in Provincia de San Juan in western Argentina (P. malesherbioides).
There is an apparent distribution gap in southernmost Peru and northernmost Chile: none of the Peruvian species
extend into Chile while the opposite is also true (Weigend 1999, Rodríguez & Weigend 2006, Weigend et al. 2008).
Presliophytum can grow in extremely arid conditions and is commonly found in dry washes and on loose scree slopes,
where it may be locally the most common or even the only perennial plant species. It usually grows on sandy or rocky
soil and ranges from near sea level up to ca. 3600 m.
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56 • Phytotaxa 329 (1) © 2017 Magnolia Press
All species are allopatric except for P. incanum, whose range shows local overlap with P. heucheraefolium in
Áncash at ca. 1000 m in the lower regions of Cordillera Negra in the Provincia Santa, e.g. along the road from Moro
to Pamparomas [(Weigend & Dostert 97/121 (F, M), Weigend & Dostert 97/120 (F, M, P)].
REVISION OF PRESLIOPHYTUM (LOASACEAE) Phytotaxa 329 (1) © 2017 Magnolia Press • 57
FIGURE 3. Reproductive morphology of Presliophytum. A. Flower of Presliophytum arequipense (cultivated, Ortiz et al. 121, BONN;
photo courtesy of M. Ackermann). Notice the relatively small corolla compared to the calyx. B. Flower of Presliophytum heucheraefolium
(cultivated, Weigend et al. 7691C, BONN; photo courtesy of M. Ackermann). C. Flower of Presliophytum incanum from Ullpan, Ancash,
Peru (Weigend & Hilger 8912C, BONN; photo courtesy of M. Ackermann). D. Flower of Presliophytum incanum from Omate, Moquegua
Peru (Ackermann & Cáceres 674, BONN; photo courtesy of M. Ackermann). E. Flower of Presliophytum malesherbioides (cultivated,
seeds collected near Chollay, Atacama, Chile (Weigend KW1024, BONN, photo by H. Hilger). The nectar scales range from entirely
yellow to mostly white but always with some yellow or green present. The range in variation of this trait and the length of the dorsal
threads appear to be clinal. F. Flower of Presliophytum sessiliflorum (Luebert et al. 3405, BONN; photo courtesy of F. Luebert). Notice the
relatively short and broad sepals, contrasting with those of Presliophytum malesherbioides. G. Nectar scale complexes of Presliophytum
incanum (Weigend 8064, B; photo by P. Beckers). The nectar scales of the other Peruvian shrubby taxa are very similar. H. Fruit of
Presliophytum heucheraefolium (Weigend et al. 7691C, BONN). The other shrubby Peruvian species have similar capsules. I. Immature
fruit of Presliophytum malesherbioides (Weigend KW1024, BONN; photo by H. Hilger). This species usually has the largest fruits of
the genus. J. Mature seed of Presliophytum heucheraefolium (Weigend et al. 7691C, BONN). The seeds of the Peruvian species of
Presliophytum are very similar to each other and amongst the smallest in Loasaceae. K. Mature seed of Presliophytum malesherbioides
(Baños del Toro, Coquimbo, Chile; Luebert et al. 3714, BONN). L. Mature seed of Presliophytum sessiliflorum (Quebrada Botija,
Antofagasta, Chile; Hoffmann 187, CONC). Although differing considerably in proportions, the seeds of the last two species have similar
seed testa cell morphology and sculpturing. Scale bars J 100 µm, K 500 µm, L 1000 µm. Photos by R. Acuña and M. Weigend, unless
otherwise credited.
Taxonomic treatment
Presliophytum (Urb. & Gilg) Weigend (2006: 467)
≡ Loasa section Presliophytum Urb. & Gilg in Gilg (1894: 118)
Type species: Presliophytum incanum (Graham) Weigend (2006: 467) ≡ Loasa incana Graham (1830: 169).
Erect 20–150 cm tall, densely branched herbs to shrubs (rarely poorly branched herbs <10 cm tall) with stinging
hairs. Scabrid hairs abundant on most surfaces, especially on abaxial leaf blade and outer ovary, glandular trichomes
sometimes present on leaves and younger stems. Taproot present, usually thickened and fleshy, rarely thin and poorly
branched. Leaves shallowly lobate, rarely toothed or sub-entire, mostly alternate (except lowermost pairs), petiole
3–100 mm, lamina 12–170 × 5–170 mm, ovate to reniform with crenate margin, rarely weakly toothed, base cuneate
to deeply cordate, apices of lobes and blade, acute to rounded. Inflorescences complex dichasia, to ca. 100 cm long,
symmetrical (in extra-Peruvian species) or asymmetrical (in shrubby Peruvian species); each flower erect or horizontal
to deflexed in anthesis, with 2 foliose prophylls (flowers apparently irregularly alternating with foliage leaves, due
to concaulescence and recaulescence) 3.0–60 × 1.0–65 mm, similar to leaves in morphology but smaller and less
disected; sepals five, 2.0–12 × 0.5–10 mm green, 3-veined, with entire margins; petals five, 4.0–25 mm long, white
(often slightly tinged green or cream) or yellow; nectar scales five, 2–7 mm long, white, yellow or greenish, usually
unicolored, rarely bicolored white and yellow or green, with 3 dorsal threads 0.5–7.0 mm long, claviform (shorter than
the nectar scale) or filiform (almost as long or longer than the nectar scale). Staminodes 2 per scale, 4–15 mm long.
Stamens 30–130. Style 3–15 mm long, straight (twisting after fertilization), ovary inferior, placentae 3 to 5, rarely 2.
Fruit a capsule, 5–15 × 3–12 mm, obconical or cylindrical to obovoid or subglobose, opening with 3–5 apical valves
(rarely apparently indehiscent); seeds 0.5–4.0 mm × 0.2–1.5 mm, testa dark to tan brown, foveate-reticulate, or with
6–18 transversal constrictions. 2n = 12, 24 (Grau 1988, Weigend 2004). Five species from the xeric regions of western
Peru, through northern Chile into western Argentina, frequent on rocky slopes.
Etymology:—‘Plant of Presl’. Dedicated to the Czech botanist Carl Presl who made important contributions to
the knowledge of Loasaceae in the 19th century.
Similar taxa:—Due to its distribution in xeric regions, alternate phyllotaxis and star-shaped, pale corollas,
Presliophytum could be confused superficially with the following Loasaceae taxa (characters of Presliophytum in
parentheses). Both Huidobria have stinging trichomes absent (vs. present), nectar scales formed by four or more
stamens (vs. always three, as indicated by the number of dorsal threads in each taxon) and seed testa either longitudinally
striate or smooth to irregularly wrinkled (vs. foveate-reticulate or transversally constricted). Nasa Weigend (2006: 465)
species with star-shaped, pale corollas have flowers pendent (vs. usually erect), dorsal threads on nectar scales absent
(vs present), and seed testa reticulate (vs. foveate-reticulate or transversally constricted). Loasa series Floribundae
Urb. & Gilg in Gilg (1894: 116, 117) occasionally have alternate phyllotaxis, but have flowers pendent (vs. usually
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58 • Phytotaxa 329 (1) © 2017 Magnolia Press
erect), nectar scales with red markings evident (vs. red absent), fruits semisuperior (vs. inferior) and seed testa deeply
pitted (vs. foveate-reticulate or transversally constricted).
Key to the species of Presliophytum
1. Herbs to sub-shrubs to 50 cm tall. Aerial structures not- to poorly lignified. Fruit with <100 seeds, each seed ca 1–2 mm long, testa
transversally constricted. Restricted to northern Chile and western Argentina ............................................................................... 2.
- Shrubs to 150 cm tall. Aerial structures lignified. Fruit with >1000 seeds, each seed ca. 0.5 mm long, testa foveate-reticulate. Re-
stricted to Peru ................................................................................................................................................................................. 3.
2. Plants annual to subperennial herbs. Leaves subentire, toothed to irregularly lobate. Sepals more than 3 × as long as wide. Nectar
scales contrasting in color with the corolla. Fruit with >10 seeds. Restricted to the interior (more than 80 Km from the ocean) of
northern Chile and western Argentina .................................................................................................................. P. malesherbioides
- Plants perennial subshrubs. Leaves always more or less regularly lobate. Sepals less than 2 × as long as wide. Nectar scales the
same color as the corolla. Fruit with(3–)4(–6) seeds. Restricted to coastal (less than 20 Km from the ocean) northern Chile .........
.................................................................................................................................................................................... P. sessiliflorum
3. Leaves reniform. Uniseriate glandular hairs abundant on young stems and leaves. Restricted to Departamentos de Áncash and
Lima ..................................................................................................................................................................... P. heucheraefolium
- Leaves ovate. Uniseriate glandular hairs very rare or absent .......................................................................................................... 4.
4. Sepals almost as long as wide. Petals subequal in size to sepals. Restricted to coastal Departamento de Arequipa ..........................
..................................................................................................................................................................................... P. arequipense
- Sepals ca. 1.5-2 × as long as wide. Petals at least 1.5 × as long as sepals. Widely distributed in the Pacific slope of Peru (Departa-
mentos de Piura to Moquegua) ......................................................................................................................................... P. incanum
1. Presliophytum arequipense Weigend (2006: 467) (Figs. 1D, 2A, B, 3A)
Type:—PERU, Arequipa [Prov. Islay], Mollendo, ca. 30 m., on rocky cliff, 27 October 1937. D. Stafford 1017 (holotype: BM barcode
BM000021454!; isotype: F No. 1508586 [photo!]).
Coarse, densely branched perennial shrub 50–100 cm tall. Stem epidermis with abundant glochidiate (sometimes
obscured) and scabrid trichomes, scattered stinging and short-smooth trichomes. Taproot present, usually thickened
and fleshy. Leaves lobate, opposite below, alternate above, petiole 4–20 mm, with glochidiate, scabrid and scattered
stinging and short-smooth trichomes, lamina 20–60 × 15–45 mm, ovate with 3–7 lobes on each side, margin crenate,
base cuneate to shallowly cordate, often asymmetric, blade and lobe apices obtuse to rounded, upperside with short-
smooth, scabrid and sparse stinging trichomes (mostly on veins or blade margins). In older leaves, the trichome apices
may fall, leaving behind basal cells, forming scale-like structures, underside densely covered in glochidiate and scabrid
trichomes (rarely with glandular and stinging trichomes). Inflorescences densely frondose, complex asymmetrical
dichasia, to ca. 50 cm long; each flower erect or horizontal in anthesis with two, sometimes sessile, prophylls (flowers
apparently solitary and irregularly alternating with foliage leaves) 3–25 × 5–25 mm, similar to vegetative leaves in
morphology and indumentum, but often narrower and weakly lobate; pedicels with glochidiate (sometimes obscured),
scabrid, short-smooth and stinging trichomes. Sepals five, broadly ovate, 5–12 × 5–10 mm green, 3-veined with
entire margins, almost as long as the petals, indumentum of each surface similar to that of the respective leaf surface;
petals five, full to half spreading, cymbiform, 5–9 mm long, cream to greenish-white, tinged darker greenish on the
abaxial surface, with scabrid, glochidiate and scattered, weak, stinging trichomes, margins flat or slightly revolute,
finely serrate and clearly distinguishable form the petal central depression; nectar scales five, 2–5 mm long, cream
to greenish-white (not contrasting with petal color), unicolored, concave, slightly bulging, with a poorly developed
papillae-margined neck and rudimentary apical wings. Filiform dorsal threads, three, 1.5–3(–5) mm long, the central
sometimes shorter than the laterals, attached subapically to the scale. Staminodes 2 per scale, 4–10 mm long, the
distal 2/3rds filiform, glabrous, the proximal third abruptly expanded, with a flange towards the nectar scale, margins
papillose. Stamens 50–75, filaments 5 mm long. Style 5 mm long, straight, twisting after fertilization, ovary inferior,
with a densely pubescent roof covered in short-smooth and scabrid trichomes, outer wall with abundant glochidiate
and stinging trichomes, sometimes with scabrid and short-smooth trichomes, placentae 3–5. Fruit a capsule 6–9 mm
diameter, subglobose, opening with 3–5 apical valves; seeds ca. 1200–3000 per capsule, 0.5 mm × 0.2–0.5 mm, testa
dark brown, foveate-reticulate. Seed testa cells polygonal.
Notes:—Although this species was collected for the first time early in the 19th century by D’Orbigny, it was
not recognized as a distinct taxon until 1997 (Weigend 2006). Its most distinctive traits are the size, proportions and
morphology of the perianth parts, which are markedly different from its close relative Presliophytum incanum (Acuña
et al. 2017).
Etymology:—The epithet alludes Arequipa, the Peruvian department to which this species is endemic.
Illustrations:—Floral scale morphology: Urban & Gilg (1900: Tab. VII. Fig. 11).
REVISION OF PRESLIOPHYTUM (LOASACEAE) Phytotaxa 329 (1) © 2017 Magnolia Press • 59
FIGURE 4. Natural distribution of Presliophytum based on herbarium specimens. P. incanum W = Presliophytum incanum with white or
indeterminate color corollas. P. incanum Y = Presliophytum incanum with yellow corollas.
ACUÑA & WEIGEND
60 • Phytotaxa 329 (1) © 2017 Magnolia Press
Distribution:—Endemic to southern Peru. So far known from only three localities very close to each other near
the coast, at elevations below 100 m in Distrito de Mollendo, Provincia de Islay, Departamento de Arequipa (Fig. 4).
Phenology:—The few known wild collections flowered in October. In cultivation, the plants flower throughout
the year.
Ecology:—This plant grows on cliffs, scree slopes and dry river beds and in the Lomas near Mollendo, sometimes
sympatrically with cacti. No information about pollinators has been obtained for this species.
Conservation status:—Although not analyzed by Rodríguez & Weigend (2006) this species is known from only
two recent collections, both from essentially the same place, which is currently under urban development. Due to its
rarity, limited range, and human pressure, we recommend this species to be considered as critically endangered (CR)
according to criteria A4bc, B2ab(i,ii,iii,iv,v). Several attempts to find the plant in the wild were unsuccessful and it
may be extinct in the wild.
Additional specimens examined:—PERU. Arequipa: Prov. Islay, Islay near Arequipa, 1833(?), D’Orbigny s.n.
(P: P00123875); Antigua trocha desde playa Catarindo hasta la Carretera Panamericana, 32 m, 8 October 2004, Ortiz
et al. 116 (BONN, HUSA); ditto, 42 m, 8 October 2004, Ortiz et al. 121 (BONN, HUSA).
2. Presliophytum heucheraefolium (Killip) Weigend (2006: 467) (Figs. 1E, 2C, D, 3B, H, J)
≡ Loasa heucheraefolia Killip (1928: 90)
Type:—PERU [Áncash, Prov. Huaraz], Tambo de Pariacota [sic], ca. 1000 m., moist cliff, 8 October 1922, F. Macbride & [W.] Featherstone
2543 (holotype: F No. 518960/Neg. No. 63414! [photo: US barcode US00115211!]; isotype: G barcode G00368197 [photo!]).
Coarse, densely branched perennial shrub 50–150 cm tall. Stem epidermis with abundant glochidiate, short-smooth
and glandular trichomes, sparse scabrid and stinging trichomes. Taproot present, usually thickened and fleshy. Leaves
lobate, opposite below, alternate above, petiole 20–100 mm, with glochidiate, short-smooth, glandular and scattered
stinging trichomes, lamina 25–170 × 30–170 mm, reniform, with 3–8 lobes on each side, margin crenate, base
deeply cordate, blade and lobe apices obtuse, upper side with numerous short-smooth, glandular and few stinging
trichomes, very rarely with scabrid trichomes, underside with glochidiate, scabrid and glandular trichomes (rarely with
stinging trichomes on veins). Inflorescences densely frondose, complex asymmetrical dichasia, to ca. 100 cm long;
each flower erect or horizontal in anthesis, with two, often sessile, prophylls (flowers apparently solitary and irregularly
alternating with foliage leaves) 20–60 × 20–65 mm, similar to vegetative leaves in morphology and indumentum;
pedicels with glochidiate, scabrid, glandular, short-smooth and scattered stinging trichomes. Sepals five, lanceolate,
10–12 × 3–5 mm green, 3-veined, with entire margins, at least twice as long as wide, indumentum of each surface similar
to that of the respective leaf surface; petals five, full spreading, cymbiform, 17–25 mm long, white to lightly tinged
greenish, darker greenish on the abaxial surface, with glochidiate, scabrid, short-smooth, glandular and scattered, weak
stinging trichomes, margins entire to wavy; nectar scales five, 5–7 mm long, white (not contrasting with petal color),
unicolored, concave, slightly bulging, with a poorly developed papillae-margined neck and rudimentary apical wings.
Filiform dorsal threads, three, 5–7 mm long, all of about the same length, attached subapically to the scale. Staminodes
2 per scale, 15 mm long, sigmoid, distal 2/3rds filiform and glabrous, proximal third abruptly expanded, with a flange
towards the scale, margins papillose. Stamens 100–150, filaments 10–15 mm long. Style 10–15 mm long, straight, but
twisting after fertilization, ovary inferior, with a densely pubescent roof, with abundant short-smooth trichomes, outer
wall with abundant glochidiate, short-smooth, glandular and stinging trichomes, placentae 3–5. Fruit a capsule 10–12
mm diameter, obovoid to subglobose, opening with 3–5 apical valves; seeds ca. 2000–5000 per capsule, 0.5 mm ×
0.2–0.5 mm, testa dark brown, foveate-reticulate. Seed testa cells polygonal.
Notes:—Killip (1928) considered this species to be closely related to Loasa pallida , but this is not correct (see
Acuña et al. 2017). The species is very distinctive due to its reniform leaves with a densely glandular indumentum.
Etymology:—The epithet refers to the similarities in leaf shape between this species and Heuchera L.
(Saxifragaceae).
Illustrations:—Floral diagram: Grau (1997: Ab. 1). Sepal morphology: Weigend (1997: Fig. 40.1).
Distribution:—Endemic to Peru. Restricted to Departamento de Áncash and the northern part of Departamento
de Lima from 400 to 1200 m (Fig. 4). Mainly on the western slope of the Cordillera Negra.
Phenology:—In the wild this species is known to flower in April, May, October and November. In cultivation it
flowers all year.
Ecology:—Presliophytum heucheraefolium grows on cliffs, dry washes, road banks and scree slopes at low to
intermediate elevations, sometimes associated with other xeric habitat plants such as cacti and Tiquilia Persoon (1805:
157). Thigmonastic stamen movements were studied by Henning & Weigend (2012).
REVISION OF PRESLIOPHYTUM (LOASACEAE) Phytotaxa 329 (1) © 2017 Magnolia Press • 61
Conservation status:—This species seems to be rare in nature and because of that, relatively poorly collected. It
was considered as endangered (EN), B1ab(iii) by Rodríguez and Weigend (2006).
Additional specimens examined:—PERU. Áncash: Prov. Santa, 49 Km above Santa in Río Santa Valley, 400
m, 13 May 2003, Weigend et al. 7653 (BONN, F); Road from Moro to Pamparomas (Caraz), Cordillera Negra, 900 m,
1997, Weigend & Dostert 97/120 (F, P); Road from Moro to Pamparomas. Arenal de Moro, 615 m, 25 November 2006,
Ackermann & Albán 615 (BONN); Road from Moro to Pamparomas, 10 October 2002, Weigend et al. 7368 (BONN);
Prov. Casma, Road from Casma to Yaután, 580 m, 10 April 2001, Weigend et al. 5536 (BONN); Prov. Huaraz, Río
Grande/Río Cacchan, 1141 m, 16 May 2003, Weigend et al. 7691 (BONN, F).
3. Presliophytum incanum (Graham) Weigend (2006: 467) (Figs. 1A, F, G, 3C, D, G)
≡ Loasa incana Graham (1830: 169)
Type:—PERU [Lima, Prov. Canta], Valley of Canta, Yazo [sic], 1830. Cruckshanks s.n. (holotype: E barcode E00085317!; isotype : BM!,
K barcode K000372846!).
= Loasa atriplicifolia Presl (1832: 61, Tab. 39). Lectotype (designated in Weigend 1998: 168):—Tab. 39 (Presl 1832).
= Loasa ruiziana Don (1834: 64). ≡ Loasa incana Ruiz & Pavón (1959: 406, Tab. 441, fig. a). Lectotype (designated in Weigend 1998:
168):—tab. 441, fig. a. (Ruiz & Pavón 1959). Epitype (designated in Weigend 1998: 168):—[PERU, Lima, Prov. Huarochirí] anno?
“Loasa sp. nova de Huayaquil” Pavón. s.n. (BM!). Possible type:—PERU [Lima, Prov. Canta], ex Obrajillo, 1778, H. Ruiz et al. s.n.
(MA barcode MA813475 [photo!])
Coarse, densely branched perennial shrub 50–150 cm tall. Stem epidermis with abundant glochidiate and scabrid
trichomes, scattered stinging and short-smooth trichomes. Taproot present, usually thickened and fleshy. Leaves lobate
(lobes more profound in younger plants), less frequently deeply thoothed, opposite below, alternate above, petiole
7–35 mm, with glochidiate, scabrid and scattered stinging trichomes (rarely with short-smooth trichomes), lamina
40–100 × 25–80 mm, ovate with (0–)3–6 lobes on each side, margin crenate or toothed, base cuneate to shallowly
cordate, sometimes asymmetric, blade and lobe apices acute, upperside with scabrid and stinging trichomes (the latter
sparse and mostly on veins), rarely with short-smooth trichomes, in older leaves the trichome tips may fall, leaving
behind basal cells forming scale-like structures, underside densely covered in glochidiate and scabrid trichomes (rarely
with stinging trichomes on veins). Inflorescences densely frondose, complex asymmetrical dichasia, to ca. 100 cm
long; each flower erect or horizontal in anthesis with two, petiolate or sessile, prophylls (flowers apparently solitary
and irregularly alternating with foliage leaves) 15–45 × 2–25 mm, similar to leaves in morphology and indumentum,
but sometimes subentire and very narrowly lanceolate (2–3 mm wide); pedicels with glochidiate, scabrid and scattered
stinging trichomes. Sepals five, lanceolate, 5–12 × 3–6 mm green, 3-veined, margins entire, more than 1.5 × long
as wide, indumentum of each surface similar to that of the respective leaf surface; petals five, half to full spreading,
cymbiform, 11–20 mm long, white (when full spreading) to beige or yellow (when half spreading), sometimes
slightly tinged greenish on the abaxial surface, with abundant glochidiate, short-smooth and scattered, weak stinging
trichomes, margins entire, vertical to slightly involute, rarely with indistinct, narrow (1 mm wide) flat margins; nectar
scales five, 4–5 mm long, white, beige or yellow (not contrasting with petal color), unicolored, concave, slightly
bulging, with a poorly developed papillose-margined neck and rudimentary apical wings. Filiform dorsal threads,
three, 5–7 mm long, of about the same length, attached subapically to the nectar scale. Staminodes 2 per scale, 10–
12 mm, distal 2/3rds filiform, glabrous, proximal third abruptly expanded, with a flange towards the nectar scale,
margins papillose. Stamens 50–75, filaments 7–10 mm long. Style 7–10 mm, straight, but twisting after fertilization,
ovary inferior, with a densely pubescent roof covered mostly in scabrid trichomes, sometimes with few short-smooth
trichomes, outer wall with abundant glochidiate, scabrid and stinging trichomes, placentae 3–5. Fruit a capsule 5–10
mm diameter, subglobose or broadly conical, opening with 3–5 apical valves; seeds ca. 1200–2500 per capsule, 0.5
mm × 0.2–0.5 mm, testa dark brown, foveate-reticulate. Seed testa cells polygonal.
Notes:—Ruiz, Pavón and Dombey were in Obrajillo in 1778 (Lang 1985). Therefore, it seems likely that H. Ruiz
et al. s.n. (MA barcode MA813475) was collected at that time and possibly is a type of Loasa incana Ruiz & Pavón
(not Loasa incana Graham). This species shows considerable plasticity in leaf morphology. As greenhouse plants age,
they produce progressively smaller leaves. The difference in size after two years is quite noticeable. Habitat also seems
to account for considerable variation: plants growing in dry river beds and cliffs often have diminutive leaves while
plants growing in dry forest edge or scrub have broader leaves. There is morphological variation related to geography
(Figs. 1F, G), but this is greatly obscured by the changes resulting of age and habitat conditions. More consistent
differences possibly related to geographic origin are evident in floral morphology as most of the the populations
from Arequipa and Moquegua have yellow, half spreading corollas (Fig. 3D) that are different from the white, full
ACUÑA & WEIGEND
62 • Phytotaxa 329 (1) © 2017 Magnolia Press
spreading corollas more common in plants further north (Fig. 3C). The type material studied and cultivated by Graham
(1830) had white, spreading corollas. It must be noticed, however, that some plants in Arequipa and Moquegua have
been reported as having white flowers, at the same time yellow flowered individuals have been collected as far north
as Lima (Fig. 4). In preserved specimens, the color of the corolla turns yellowish, independently of the origin of the
plants, and, in the absence of field notes, it is unclear whether white and yellow flowered populations overlap with
each other, and how extensive is this overlap, if any. Plants with white flowers tend to have stems predominantly with
scabrid trichomes while yellow flowered plants have stems mostly with glochidiate trichomes, but this difference
appears to be minor and not always consistent. Preliminary genetic evidence coming from plastid markers suggests
that the yellow-flowered populations from the south could be more closely related to P. arequipense than to the
northern white-flowered populations. But more robust evidence is needed before making a taxonomic decision.
Etymology:—The epithet refers to the hoary appearance of the plants due to their abundant scabrid and glochidiate
trichomes.
Illustrations:—Habit and morphology: Presl (1832: Tab. XXXIX), Urban & Gilg (1900: Tab. VII. Fig. 1–10),
Ruiz & Pavón (1959: Icon. CDXLI.a). Leaf: Weigend (1997: Fig. 21.8). Inflorescence architecture: Urban (1892a: Taf.
XII.6), Weigend (1997: Fig. 29.2), Weigend et al. (2004b: Fig. 6C). Floral diagram: Urban (1892b: Taf. XIV.21), Gilg
(1894: Fig. 37N), Grau (1997, Ab. 3). Sepal morphology: Weigend (1997: Fig. 40.2). Petal ontogeny: Weigend (1997:
Fig. 43.13–14). Nectar scale ontogeny: Weigend (1997: Fig. 53.2 , mislabeled as “Loasa grandis”). Fruit: Weigend
(1997: Fig. 56.20).
Distribution:—Endemic to Peru. Known from Departmento de Piura to Departmento de Moquegua, from sea
level to over 3000 m elevation. This species is very widely distributed on the Pacific slope of Peru, but is largely
replaced by P. heucheraefolium in coastal Departamento de Áncash (Fig. 4).
Phenology:—This species is known to flower all year round.
Ecology:—This is one of the most widespread taxa of Loasoideae, with a very broad ecological tolerance in dry
habitats. Like other species of the genus, it grows on cliffs, in dry washes, on road banks and scree slopes at low to
intermediate elevations, sometimes associated with cacti and other dry scrub plants. It can also be found in Andean
scrub, coastal lomas and disturbed habitats.
Conservation status:—This species fares well in human disturbed habitats and is one of the most abundant
species of Loasaceae in Peru. Due to its abundance and resilience to human disturbance it is considered a LC species
(Rodríguez & Weigend 2006).
Additional specimens examined:—PERU. Dept. Unknown: San Mateo in the Quebrada, s.a., coll. Unknown
696 (K: K000372847); s.a., Martinet s.n. (P: P04589533); s.a., Martinet 191 (P: P04589534); San Bartolomé, July
1874, Martinet 168 (P: P04589536, P04589537); s.a., Neé s.n. (F: n.842915); Piura: Prov. Unknown, Pariñas Valley,
35 miles east of Cape Pariñas, 4 September 1927, Haught 186 (F); Prov. Talara, Pariñas valley, 20 miles inland, s.a.,
Haught F-111 (F); Cajamarca: Prov. Santa Cruz, 35 Km from Santa Cruz on road to Catache, 1 Km after Catache,
4 May 2003, Weigend et al. 7546 (BONN); Prov. San Miguel, Entre Quindén y Platanal (carretera hacia el Pueblo de
Unión Agua Blanca), 800 m, 6 October 2001, Rodríguez et al. 2423 (F); Prov. Contumazá, Alrededores de Tembladera,
900 m, 23 May 1976, Sagástegui et al. 8529 (F); Road from Pacasmayo to Cajamarca, ca. 20 Km from Pacasmayo on
rocky roadside, 500 m, 1998, Dostert 98/165 (F); Road from Chilete to Pacasmayo, 900 m, 1997, Weigend et al. 97/457
(F); Ca. 30 Km from Chilete on road to Contumazá, 9 May 2003, Weigend et al. 7585 (BONN); Al N. de Contumazá
sobre el camino que conduce a Chilete, y que se desvía de la carretera Contumazá–Chilete, bajando Hoyada Verde,
1600 m, 3 July 1983, Sánchez et al. 3195 (F); Chilete-Contumazá road, about midway between the villages; 11 April
2003; Hufford et al. 4018 (F); Alrededores de San Benito, 1300 m, 3 February 1985, Sagástegui et al. 12461 (BONN,
F); El Portachuelo (Ascope - El Algarrobal), 780 m, 20 April 1984, Sagástegui 11387 (BONN); La Libertad: Prov.
Gran Chimú, Cascas–Contumazá road, 1.1 Km north of square in Cascas, 1350 m, 10 April 2003, Hufford et al.
4013 (F); Prov. Ascope–Prov. Trujillo, Cerro Cabezón, 800 m, 3 July 1985, Mostacero et al. 767 (F); ditto, 250 m, 4
November 1983, Sagástegui & López 10988 (F); ditto, 500 m, 8 May 1999, Sagástegui et al. 16142 (BONN, F); Prov.
Otuzco, Ruta Simbal–La Cuesta, 1280 m, 2 September 1973, López & Sagástegui 8008 (F); Prov. Trujillo, Pedregal,
800 m, 1 May 1994, Sagástegui 15289 (F); Pedregal a Shirán, 300 m, 4 February 1974, Lourteig & López 2994 (P);
Road Trujillo–Otuzco near Shiran, 600 m, 1997, Weigend et al. 97/198 (F); Alrededores de Shirán, 550 m, 10 June
1993, Leiva 772 (F); Trujillo–Otuzco road, 31.5 Km east of the PanAmerican Highway in Trujillo and 6.2 Km west of
Puente Shirán, 900 m, 15 April 2003, Hufford et al. 4025 (F); Prov. Virú, Lomas de Virú. Cerro de las Lomas, 350 m,
12 October 2000, Weigend et al. 2000/695 (BONN, F); Áncash: Prov. Corongo, Road from Huallanca to Yanac, near
Yanac, 2800 m, 7 March 2001, Weigend et al. 5013 (BONN); Road Sihuas to Corongo/Mirador (on Río Santa), 3065
m, 26 April 2004, Weigend & Schwarzer 8039 (BONN, F); Prov. Huaylas, 133 Km from Santa on road to Caraz, 2
REVISION OF PRESLIOPHYTUM (LOASACEAE) Phytotaxa 329 (1) © 2017 Magnolia Press • 63
Km after Huallanca, 13 May 2003, Weigend et al. 7655 (BONN, F); Road from Caraz to Huaylas, ca. 2 Km after the
turnoff to Huaylas from the Carretera Central, 2614 m, 28 November 2014, Henning et al. 9719 (BONN); Cordillera
Negra, 20.5 Km from Caraz on road to Huaylas, 2278 m, 29 April 2004, Weigend & Schwarzer 8048 (BONN, F);
Surrounding of Pamparomas to Tuteycon, 1950 m, 25 November 2006, Ackermann & Albán 616 (BONN); Serpentine
outside fields Shauintioc and Tuteycon, 15 May 2003, Weigend et al. 7688 (BONN); Road from Pamparomas to
Moro, branch to Ullpan, 2120 m, 14 October 2007, Weigend & Hilger 8912 (BONN); Prov. Santa, Road from Moro to
Pamparomas (Caraz), Cordillera Negra, lower desertic regions, 1400 m, 1997, Weigend & Dostert 97/121 (F); Road
from Moro to Pamparomas, 10 October 2002, Weigend et al. 7367 (BONN, F); Lima: Prov. Unknown, s.a., Dombey
s.n. (P: P04588969); Road to Puruchuco, s.a., McLean s.n. (K: K000372845); Prov. Huaura, Ámbar-Huaura, Laderas
de Cerros, 1200 m, 6 August 2003, coll. Unknown 3267 (BONN); Prov. Canta, Ex Obrajillo, s.a., Ruiz et al. s.n. (MA:
MA813475); Canta por abajo, 2300 m, 2 April 1953, Petersen & Ginting 1194 (L); Quives, open rocky slope, 1300
m, 9 June 1925, Pennell 14309 (F); Prov. Lima, Canta Valley, 7 km NE of Trapiche. On sandy sides of dry wash; 800
m; 4 August 1957, Hutchinson 1012 (F); Road from Trapiche to Quilca at ± 6 Km from Trapiche. Dry stream bed in
Tillandsia desert. Granite sand, no cacti, 750 m, 02 January 1971, Hawkes et al. 4103 (L); Chosica, 800 m, June 1949,
Soukup 3796 (F); Prov. Huarochirí, Near Huínco, above Chosica, 1900 m, 3 September 2004, Richter s.n. (BONN);
Carretera Central, just west of Matucana, 2300 m, 1997, Weigend & Dostert 97/12 (F); Matucana. Steep rocky canyon
slope; soil loose, 2500 m, 19 April 1922, Macbride & Featherstone 257 (F); Prov, Yauyos: Road from Yauyos to
Jauja, few Km after Magdalena, 2300 m, 7 October 2002, Weigend et al. 7233 (BONN); Road from Huancayo to San
Vicente de Cañete. 193 Km from Huancayo, 872 m, 22 September 2001, Weigend & Skrabal 5888 (BONN, F); Ica:
Prov. Unknown, s.a., Martinet 47 (P); Prov. Pisco, 1 Km before Puente Huaytará (Km 73 road Pisco-Ayacucho), 1450
m, 29 September 1997, Weigend & Förther 97/585 (F); Prov. Nazca, Sol de Oro, 840 m, 2 January 2007, Huamantupa
8432 (BONN); Km 17 on Road Nazca–Puquio, 1140 m, 2 October 1997, Weigend & Förther 97/642 (F); Arequipa:
Prov. Caravelí, Quebrada Ático, 50 m, 14 February 1998, Cátedra Ecología, s.n. (FLSP 1343) (P: P04574610); Prov.
Condesuyos, Road from Aplao (Castilla) to Chuquibamba, S of bridge over Río Arma, Quebrada Huario, ca. 24.5–26
Km from Chuquibamba, 1550 m, 24 July 2010, Weigend et al. 9374 (BONN); Prov. Camaná, Km 934 Panamericana
Sur between Camaná and Tambillo, 1500 m, 5 October 1997, Weigend & Förther 97/760 (F); Moquegua: Prov.
General Sánchez Cerro, Omate. Laderas de cerros y bordes de camino, 2400 m, 15 September 2004, coll. Unknown
3239 (BONN); Anexo de ‘Laje’–San Francisco, 2270 m, 8 April 2003, Cáceres et al. 3014 (BONN); Road from Omate
to San Francisco above Omate. Hillsides of Urimalle, 1840 m, 8 December 2006, Ackermann & Cáceres 674 (BONN,
F); From Moquegua to Omate, 2798 m, 14 April 2004, Weigend & Schwarzer 7869 (BONN); Prov. Mariscal Nieto,
Road Moquegua to Omate, 74 Km from Moquegua, 1 Km before puente over Río Tambo, 14 April 2004, Weigend &
Schwarzer 7862 (BONN, F); Off Moquegua–Torata road, just above Torata, 14 September 2001, Hufford & McMahon
3835 (F); 20 Km E of Moquegua on road to Torata, 2100 m, 13 October 1997, Weigend & Förther 97/850 (F); 14 Km
E of Moquegua on road to Torata, 1855 m, 13 October 1997, Weigend & Förther 97/848 (F); Km 1126 Panamericana
Sur. 14 Km N of Moquegua turnoff, 1200 m, 14 October 1997, Weigend & Förther 97/855 (F); Río seco o aluvión,
1200 m, 9 April 1959, Vargas 12640 (BONN); Cerca a Moquegua. Cauce seco, 800 m, 27 October 1966, Vargas 17970
(BONN).
4. Presliophytum malesherbioides (Phil.) R.H. Acuña & Weigend in Acuña et al. (2017: 373) (Figs. 1C, 3E, I, K)
≡ Loasa malesherbioides Philippi (1864:74)
Type:—[CHILE, Coquimbo, Prov. Elqui] Baños del Toro, 1860/61, [H.] Volckmann s.n. (SGO?, B [†, photo F Neg. No.10208!]).
= Loasa longiseta Philippi (1865: 347). Lectotype (designated in Acuña et al., 2017: 373):—[CHILE, Atacama, Prov. Copiapó] Quebrada
de Puquios, Des. Atacama, 1865, F. Geisse s.n. (SGO barcode SGO000003405 [photo!]; isolectotype: SGO barcode SGO000003404
[photo!]).
Densely branched annual to subperennial herb to ca. 30 cm tall, less frequently ephemeral, sparsely branched
herbs 5–15 cm tall. Stem base sometimes with scarce secondary xylem and large parenchymatous pith, epidermis
with abundant glochidiate, scabrid and stinging trichomes, younger portions with glandular trichomes (rarely absent).
Root system poorly branched, taproot long (sometimes as long as the shoot is tall) and thin. Leaves subentire
to irregularly lobate or deeply thoothed, usually only the lowermost pairs opposite, alternate above, petiole 3–45
mm, with glochidiate, scabrid, glandular and stinging trichomes, lamina 12–65 × 5–47 mm, ovate with 0–8 lobes/
teeth on each side, margin weakly sinuous to deeply toothed, base cuneate, blade and lobe apices obtuse to acute,
adaxial surface with scabrid, glochidiate and stinging trichomes (mostly on veins and leaf margins) the amount of
stinging trichomes variable, glandular trichomes, when present, restricted to the lamina base, abaxial lamina with
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abundant glochidiate trichomes, sometimes sparse scabrid and stinging trichomes, glandular trichomes, if present,
restricted to the base. Inflorescences frondose dichasia, to 15 cm long (in small plants shorter, with only 1–5 flowers),
trichome cover similar to the stem, but glandular trichomes sometimes more abundant; each flower erect or horizontal
in anthesis with two, shortly petiolate to subsessile, prophylls, 2 per flower (flowers apparently irregularly alternating
with the prophylls), 3–25 × 1–15 mm, similar to vegetative leaves in morphology and indumentum, but diminishing
in size towards the terminal part of the inflorescence (sometimes very reduced in size); pedicels 5–20 mm long with
glochidiate, scabrid, glandular and stinging trichomes, lengthening considerably (up to 40 mm) after anthesis. Sepals
five, narrowly lanceolate to linear, 2–6 × 0.5–1 mm, more than 3 × as long as wide, green, only the central vein
conspicuous, margins entire, indument of each surface similar to that of the respective leaf surface; petals five, full
spreading, cymbiform, 4–7 mm long, white, with abundant glochidiate, scabrid and scattered stinging trichomes on
the outer surface, margins entire, often meeting over the midline of the petal; nectar scales five, 2–3 mm long, entirely
yellow to mostly white with green or yellow markings (contrasting with petal color), concave, bulging towards the
base (specially southern plants: with small round nectar sacs), with a median keel below the neck and apical wings,
dorsal threads, three, claviform 0.5–1 mm long, of similar lengths, the tips reaching the scale apex or well beyond it
(longer threads in northern plants), attached to the upper part of the scale, below the neck. Staminodes 2 per scale, 5–6
mm, distal 3/4ths filiform, papillose, tips slightly expanded, proximal fourth with long papillae, abruptly expanded,
with a flange towards the scale. Stamens ca. 30–60, filaments 2–4 mm long. Style 3–4 mm long, straight, but twisting
after fertilization, ovary inferior, with a pubescent roof covered in scabrid and glochidiate trichomes, outer wall with
abundant, large glochidiate, and stinging trichomes, placentae 3. Fruit a cylindrical to slightly ovoid capsule, 5–15(–
28) × 3–6(–10) mm, usually >2 × long as wide, opening with 3–5 apical valves; seeds ca. 14–30(–60) per capsule, 2–3
× 1.0–1.5 mm, testa dark brown, with 6–9 very evident transversal constrictions Seed testa cells tetragonal, periclinal
walls with undulate sculpturing.
Notes:—There is considerable diversity in the morphology of this species. As it happens with other short lived
taxa in Loasaceae, such as the species of the Nasa triphylla group (Dostert & Weigend 1999), the generation time
and founder effect may be responsible of the significant morphological variation in this species. The “setae” (stinging
trichome) cover in leaves and petioles used by Philippi (1865) to differentiate L. longiseta from L. malesherbioides
show considerable variation within and between populations. Plants in the north (formerly called longiseta), tend to
have higher density of foliar stinging trichomes, but most plants, independently of their locality, have at least some
of these. The floral scale morphology and color vary geographically: plants from the southern part of the range have
mostly yellow scales with well-definded, round nectar sacs and dorsal threads that extend to or barely beyond the
nectar scale neck. Plants in the northern part of the range, have mostly white scales with green or yellow markings,
no distinct nectar sacs, and dorsal threads that extend well beyond the scale neck. The plants from Chollay-Conay and
neighboring areas in Provincia de Huasco, Región de Atacama, seem to be intermediate between northern and southern
populations, with mostly cream colored scales having yellow-green markings, dorsal threads extending slightly above
the scale neck and poorly developed nectar sacs. The specimen S. Teillier & P. Barahona 6285 (CONC) differs in
several regards from the other studied specimens of the species in that the leaves have deep clefts (ca 25% of leaf
width), the nectar scales are white with inconspicuous pale green markings near the base, with dorsal threads attaching
directly to the lower rim of the neck, and the mature fruits are larger (18–28 × 5–10 mm) and with more seeds (ca.
60) than usual for the species. However, considering the variability of P. malesherbioides, we have decided to include
these plants in our concept of the species. The dwarf, sexually mature, basically unbranched specimens <10 cm tall are
similar in habit to dwarf specimens of Nasa chenopodiifolia (Desr.) Weigend in Weigend et al. (2006: 73), N. urens
(Jacq.) Weigend in Weigend et al. (2006: 83) and Aosa rostrata (Urb.) Weigend (2006: 464) as described by Urban &
Gilg (1900) and Henning & Weigend (2009).
Etymology:—The epithet refers to the the similarity of this plant to some species of Malesherbia Ruiz & Pavón
(1794: 45).
Illustrations:—Habit and morphology: Hoffmann et al. (1998: p. 73.1, p. 75.4), Pérez-Moreau & Crespo (2003:
Fig. 156). Floral diagram: Grau (1997: Ab. 3). Nectar scale morphology and variability: Urban & Gilg (1900: Tab. VI.
Fig. 7–10).
Distribution:—Presliophytum malesherbioides is known from Región de Atacama and Región de Coquimbo in
Chile as well as from Provincia de San Juan, Argentina (Pérez-Moreau & Crespo 2003). It is found between 1200 and
3600 m, and more than 80 km inland from the Pacific Ocean (Fig. 4).
Phenology:—Known to flower between October and March.
Ecology:—This is the only annual species of the genus. It inhabits very dry areas and it is often one of the few
species of vascular plants growing in such localities, where it can be abundant.
REVISION OF PRESLIOPHYTUM (LOASACEAE) Phytotaxa 329 (1) © 2017 Magnolia Press • 65
Conservation status:—Presliophytum malesherbioides is considered either LC or DD by Marticorena et al.
(2001) and Squeo et al. (2008). This species can be frequent in remote areas.
Additional specimens examined:—CHILE. Atacama: Prov. Unknown, coll. unknown (E: E00158252); February
1888, Philippi s.n. (K: K000372859); Prov. Chañaral, Cuesta Pedernales, 3215 m, 28 February 2007, Letelier & Squeo
1224 (CONC); Prov. Copiapó, Camino al Salar de Maricunga, Km 62, 2250 m, 31 January 1963, Ricardi et al. 557
(CONC); Quebrada de Paipote. Extremo superior Vegas La Junta, en terreno pedregoso, 2940 m, 06 January 1973,
Marticorena et al. 522 (CONC); Quebrada del Peñón, 3600 m, 9 March 1996, Brownless et al. 572 (E); Camino a la
Quebrada de las Vizcachas, a 37 Km de La Puerta, 2900 m, 1 February 1963, Ricardi et al. 631 (CONC); Portillo de
Acerillos, en la bajada, 3500 m, 30 January 1949, Krapovickas & Hunziker 5722 (BAB); Río Turbio-vegas, 3170 m, 16
February 2009, Teillier & Barahona 6285 (CONC); Valle del Río Jorquera, 12 January 1970, Zöllner 4055 (CONC);
Im Jorqueratal an einem sandigen Hang, 1200 m, 12 January 1970, Zöllner 4259 (L); Estancia Manflas en las faldas
de los cerros, entre piedras sueltas, 25 October 1965, Ricardi et al. 1480 (CONC); Prov. Huasco: Río Laguna Grande,
entre Potrero de Toledo y Quebrada Candelilla, 2400–2800 m, 13 February 1981, Kalin-Arroyo 81545 (CONC); Río
Laguna Grande, entre Las Papas y Potrero de Toledo, 2000–2400 m, 19 January 1983, Marticorena et al. 83342
(CONC); Cajón del Río Conay, 3 Km al interior de Conay, en taludes, 1450 m, 13 October 1983, Marticorena 9557
(CONC); Coquimbo: Prov. Elqui: Baños del Toro, coll. unknown (K: K 000372858); Vegas de los Baños del Toro, s.a.,
Philippi s.n. (K: K000372857); Canchas de Sky, 3400 m, 24 February 1988, F. Squeo 88157 (CONC); Río La Laguna
3.6 Km de central, 2174 m, 19 December 2006, Rosas 4371 (CONC); Camino Internacional a San Juan entre Juntas
y Embalse La Laguna, Km 4, 2100 m, 06 January 1967, Ricardi et al. 1720 (BAB, CONC); Camino entre Juntas y
Embalse La Laguna, 2300–2900 m, 09 January 1981, Kalin-Arroyo 81149 (CONC); Camino al Embalse de La Laguna
a 20 Km de La Junta, 2700 m, 05 February 1963, Ricardi et al. 716 (CONC); Camino entre Embalse La Laguna y
Campamento del Embalse, 2900–3200 m, 08 January 1981, Kalin-Arroyo 81105 (CONC); Embalse La Laguna, 3050
m, 11 January 1966, Peña s.n. (CONC).—ARGENTINA. San Juan: Dept. Calingasta, Río Melchor, 2800 m, 2
February 1991, Kiesling et al. 7814 (SI); Río Melchor a Co. Guanaqueros, 2700 m, 6 February 1991, Kiesling et al.
7823 (SI); Río Manantiales al NW de Calingasta, 3200 m, 15 February 1990, Kiesling et al. 7489 (BAB, SI).
5. Presliophytum sessiliflorum (Phil.) R.H. Acuña & Weigend in Acuña et al. (2017: 373) (Figs. 1B, 3F, L)
≡ Loasa sessiliflora Philippi (1893:12)
Type:—[CHILE, Antofagasta, Prov. Antofagasta] Sierra Esmeralda, Des Atacama, 20 October 1883, [F.] S[an] Roman s.n. (holotype:
SGO barcode SGO000003420 [photo!]).
Densely branched subshrub to ca. 50 cm tall. Stem epidermis green, with abundant glochidiate, scabrid and stinging
trichomes, glandular trichomes in younger parts. Taproot perennial, fleshy and thick. Leaves opposite below, alternate
above, petioles to 20 mm long in basal leaves, similar to the stem in trichome cover, but with more glandular
trichomes especially near the leaf blade, terminal leaves mostly (sub)sessile, lamina 20–60 × 7–35 mm, ovate with
3–8 triangular lobes on each side, margin toothed, base truncate, sometimes slightly asymmetrical, blade and lobe
apices acute, adaxially with numerous scabrid, short smooth, glandular and stinging trichomes, rarely with few
glochidiate trichomes, abaxially with abundant glochidiate trichomes, stinging trichomes restricted to the larger veins.
Inflorescences frondose dichasia, to 10 cm long, the trichome cover similar to the stem, but with more glandular
trichomes; flowers horizontal to deflexed in anthesis, with two, sessile prophylls per flower (flowers apparently
irregularly alternating with the prophylls), 3–17 × 2–10 mm, diminishing in size towards the terminal portions of the
inflorescence, similar to vegetative leaves in trichome cover but usually only slightly serrate to dentate with 3–4 teeth
per side, flowers subsessile or with pedicels, shorter than the petals, to 4(–6) mm, with glochidiate, glandular and
stinging trichomes. Sepals five, broadly lanceolate to ovate, 2.5–5 × 2.5–4 mm, <1.25 × as long as wide, green,
3-veined, margins entire, indumentum of each surface similar to that of the respective leaf surface but with less
glandular trichomes; petals five, full spreading, cymbiform, 7–14 mm long, white or very light greyish, tinged greenish
on the abaxial surface with abundant scabrid, glochidiate, glandular and rarely weak stinging trichomes adaxially,
margins slightly undulate; nectar scales five, 3–4 mm long, white (not contrasting with petal color), concave, slightly
bulging, apex weakly bilobate, neck with a weak rim, rudimentary apical wings . Dorsal threads, three, filiform,
of about the same length, to ca. 3 mm long, attached to the tip of the scale. Staminodes 2 per scale, to ca. 10 mm
long, S-shaped, the distal 2/3rds filiform and glabrous, the proximal third abruptly thickened, flattened and papillose.
Stamens 30–50, filaments 5–10 mm long. Style 10 mm long, straight, but twisting after fertilization, persistent in fruit,
the basal portion with scabrid trichomes; ovary inferior, with a densely pubescent roof with scabrid trichomes, outer
wall with abundant scabrid and stinging trichomes, placentae 2. Fruit a 2 locule capsule 5–6 × 3 mm (not counting
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the persistent sepals), obovoid, apprently indehiscent; seeds (3–)4(–6), two per locule, 3–4 mm × 1 mm, narrowly
ovoid, testa tan brown, darker towards hilar end, with 12–18 transversal constrictions. Seed testa cells tetragonal,
periclinal walls with undulate sculpturing.
Notes:—The name Loasa longiseta has been often misapplied to this species (Weigend et al. 2008). Urban & Gilg
(1900) knew about this species and considered it possibly related to Loasa longiseta, but they were unable to examine
the only specimen known at the time (the holotype). Its taxonomic status has been clarified only recently (Acuña et al.
2017). The dimerous gynoecia and two-seeded locules observed in this species are rare in the tribe Loaseae.
Etymology:—The epithet refers to the short-pedicellate to subsessile flowers of this species.
Illustrations:—Inflorescence architecture: Weigend et al. (2004b: Fig.6A incorrectly called “Loasa longiseta”).
Floral diagram: Grau (1997: Ab. 3).
Distribution:—Endemic to Chile. Presliophytum sessiliflorum grows only in scattered localities in coastal
mountain ranges of the Región de Antofagasta and possibly northernmost Región de Atacama, Chile, at elevations
under 1000 masl, and less than 20 km inland from the Pacific Ocean (Fig. 4).
Phenology:—Known to flower between October and April.
Ecology:—This plant seems to be restricted to habitats with oceanic influence. The capsules are apparently
indehiscent and thus the fruit and the seeds are expected to be dispersed as a single unit.
Conservation status:—It has been reported by Johnston (1929) and by Jiles, in a specimen label, that this
species could be common locally [Jiles 5343 (CONC)], and may occur in disturbed habitats, e.g., La Chimba NE of
Antofagasta [(Luebert et al. 3405 (BONN)]. Marticorena et al. (1998) recorded this species for Región de Antofagasta,
but its conservation status was not analyzed. Due to our rudimentary knowledge of its abundance and distribution we
consider Presliophytum sessiliflorum as DD.
Additional specimens examined:—CHILE. Antofagasta: Prov. Tocopilla, La Carmelita, 750 m, 8 November
1969; Jiles 5343 (CONC); Prov. Antofagasta: Quebrada La Chimba, 340 m, 18 October 2016, Luebert et al. 3405
(BONN); bare rocky canyon, 200 m, 3 April 1925, Pennell 13026 (F); Quebrada de Botija, al norte de Paposo, 400
m, 29 November 1988, Hoffmann 187 (CONC); Sierra Esmeralda, along trail between Posada de los Hidalgos and
Quebrada Cachina via Portezuelo de Mina Carola. 1.5 Km N, 14 December 1925, Johnston 5674 (F).
Acknowledgements
Federico Luebert made very valuable comments during the process of this revision. Him and Tim Böhnert generously
provided specimens and images of much needed Chilean plants, and their diligence is very appreciated. Markus
Ackermann and María T. Eyzaguirre kindly allowed us to use photographs of their authorship. Birgit Emde took care
of the living collections of Presliophytum and Huidobria in Botanischer Gärten der Universität Bonn. Hans-Jürgen
Ensikatt and Adeel Mustafa corteously provided technical help with the SEM images. The staff at CONC (in particular
Alicia Marticorena), BAB and SI are corteously recognized for the loan of specimens or for providing images for this
study. Norbert Holstein provided useful insights on the correct spelling of heucheraefolia. Two anonymous reviewers
made very valuable suggestions to improve the quality of the manuscript. The first author’s studies in Germany have
been supported by the ALECOSTA joint program with funds coming from both the Universidad de Costa Rica and the
DAAD.
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