Coronilla montserratii, a new hexaploid annual species from the eastern Balearic Islands

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SUMMARY: A new species, Coronilla montserratii, is described from the coastal and inland sand dunes of Minorca (Balearic Islands). The new species is hexaploid (2n=36), the highest ploidy level so far known in annual Coronilla species. Morphological features suggest that C. montserratii is related to the tetraploid C. repanda, from which it could be discriminated by several leaf features. The join evaluation of morphological and molecular data suggests that C. montserratii is an allopolyploid species. Ribosomal ITS sequences identified C. scorpioides as a likely progenitor, but the other progenitor species remains elusive on molecular grounds. Based on the close morphology shared between C. montserratii and C. repanda it is hypothesized that the latter could be also involved in the origin of the new hexaploid species.
RESUMEN: Se describe una nueva especie, Coronilla montserratii, de las dunas costeras y arenales interiores de Menorca (Islas Baleares). La nueva especie es hexaploide (2n=36), el nivel de ploidía conocido más elevado en las especies anuales de Coronilla. La morfología de la planta sugiere que C. montserratii está relacionada con C. repanda (tetraploide), de la que se distingue por diversos caracteres foliares. El análisis conjunto de datos morfológicos y moleculares sugieren que C. montserratii es una especie alopoliploide y que C. scorpioides y C. repanda pueden haber intervenido en su origen.

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Flora Montiberica 46: 19-26 (X-2010) ISSN 1138-5925
CORONILLA MONTSERRATII, A NEW HEXAPLOID ANNUAL
SPECIES FROM THE EASTERN BALEARIC ISLANDS

Pere FRAGA* & Josep A. ROSSELLÓ**
* Consell Insular de Menorca, Plaça de la Biosfera 5, E-07703 Maó (Balearic Islands,
Spain). pere.fraga@gmail.com.
** Jardí Botànic, Universitat de València. C/Quart 80, E-46008 València, and Jardí
Botànic Marimurtra, Fundació Carl Faust, E-17300 Blanes (Barcelona). rossello@uv.es.


SUMMARY: A new species, Coronilla montserratii, is described from the
coastal and inland sand dunes of Minorca (Balearic Islands). The new species is
hexaploid (2n=36), the highest ploidy level so far known in annual Coronilla
species. Morphological features suggest that C. montserratii is related to the
tetraploid C. repanda, from which it could be discriminated by several leaf
features. The join evaluation of morphological and molecular data suggests that C.
montserratii is an allopolyploid species. Ribosomal ITS sequences identified C.
scorpioides as a likely progenitor, but the other progenitor species remains elusive
on molecular grounds. Based on the close morphology shared between C.
montserratii and C. repanda it is hypothesized that the latter could be also involved
in the origin of the new hexaploid species. Key Words: Polyploidy, Loteae,
Fabaceae, endemism, insular flora, taxonomy
RESUMEN: Se describe una nueva especie, Coronilla montserratii, de las
dunas costeras y arenales interiores de Menorca (Islas Baleares). La nueva especie
es hexaploide (2n=36), el nivel de ploidía conocido más elevado en las especies
anuales de Coronilla. La morfología de la planta sugiere que C. montserratii está
relacionada con C. repanda (tetraploide), de la que se distingue por diversos
caracteres foliares. El análisis conjunto de datos morfológicos y moleculares
sugieren que C. montserratii es una especie alopoliploide y que C. scorpioides y C.
repanda pueden haber intervenido en su origen. Palabras clave: Poliploidía,
Loteae, Fabaceae, endemismo, flora insular, taxonomía.

Coronilla L. is a temperate genus of GARCÍA MARTÍN & TALAVERA,
legumes belonging to the tribe Loteae 2000). During field work aimed at increa-
which shows a mainly Mediterranean dis- sing the floristic knowledge of the sandy
tribution with several species extending to areas of Minorca (Balearic Islands), we
northern European latitudes (UHROVÁ, found several populations resembling C.
1935). The two annual species of Coro- repanda but showing a deviant morpho-
nilla, C. repanda and C. scorpioides, have logy concerning the shape of leaves and
been included within sect. Scorpioides leaflets. In addition, cytogenetic studies
Bent. (UHROVÁ, 1935). A third entity, revealed that the Minorcan plants were
C. dura (Cav.) Boiss. is not unanimously highly polyploid and differed from pre-
recognized as a distinct species and has vious chromosome numbers so far repor-
been usually included within C. repanda ted in annual species of Coronilla.
at the subspecific level (BALL, 1968;
19 Coronilla montserratii, a new species from Minorca
The combination of morphological Diagnosis: A Coronilla repanda simi-
characteristics of diagnostic value and lis, sed robustior, foliolis longiores et la-
ploidy level suggest that the plants from tiores, foliae composita cum foliolis hete-
Minorca belong to an entity not previous- romorphi, legumina latiores et robustior,
ly described, and it is presented in this et chromosomatum numerum (2n=36) dif-
paper as a new species. fert.
Holotype: SPAIN: Balearic Islands. Mi-
norca: Arenal de Macarelleta, Ciutadella de
MATERIALS AND METHODS Menorca (31SEE7921), fixed calcareous sand
dunes with low scrub, 20 m, 31-03- 1996, P.
Plant material. Living material from C. Fraga (VAL 190331). Isotype: herbarium P.
repanda and C. scorpioides was collected .
from populations across Minorca. Vou- Description: Ascending or erect, gla-
cher specimens are preserved at VAL. brous, glaucous annual. Stem 10-40 cm
Morphological observations were based long, subterete or obscurely angled, bran-
on living material examined in the field ched from the base and upwards. Leaves
and herbarium specimens from the her- slightly fleshy, heteromorphic. Basal lea-
baria BC, MA, VAL (abbreviations accor- ves simple, unifoliate, petiolate, oblong,
ding to HOLMGREM & al. 1990). 0.5-3.5 cm long, 0.3-2.8 cm wide, apex
Chromosome preparations. Seeds were rounded or truncate, base broadly cuneate,
germinated on solid agar in Petri dishes in border entire. Medium leaves, petiolate,
a constant temperature of 20ºC and 12 3-7 foliolate. Leaflets heteromorphic, the
hours of white light daily. Root tips were terminal 0.7-2 x 0.4-1.4 cm, longer than
pre-treated with 0.05% colchicine solu- the lateral ones, apex usually emargina-
tion at room temperature for 2-3 hours, ted, mucronate, base narrowly cuneate,
washed with distilled water, fixed in fresh border entire; lateral leaflets orbicular to
Carnoy I solution overnight and stored in obovate, 0.5-1.5 x 0.3-1.2 cm, the lower
70% ethanol at 4ºC until used. For chro- pair bigger than the apical one, apex roun-
mosome counts root tips were hydrolysed ded, mucronate, base rounded to broadly
for 5-10 min in 1M HCl at 60ºC, and cuneate, border entire; basal leaflets clear-
washed and stained in Feulgen solution ly distinct, obcordate to ear shaped, 0.2-
for 1-2 h. Stained meristems were squa- 1.2 x 0.15-0.8 cm wide, apex obtuse to
shed in a drop of 45% acetic acid and emarginate, sometimes mucronate. Upper
permanent preparations were made by leaves with up to five leaflets, heteromor-
mounting in Canada balsam. Photomicro- phic; stipules connate, 1.5-3 mm long, al-
graphs of well-spread metaphases were most as long as wide, membranous, apex
taken with an Olympus Camedia C-2000- clearly bifid, teeth sometimes acuminate.
Z digital camera and processed with Ado- Inflorescences 2-5 flowered, arising from
be Photoshop 7.0. Chromosome counts the axils of the upper leaves. Peduncles 1-
were made from at least five well-spread 4 cm long, exceeding the subtending leaf
metaphases by direct observation and and lengthening in fruit; bracts connate,
from the photomicrographs. Chromosome up to 1 mm long, deltoid, membranous;
measurements were made on digital ima- pedicels short, curved, up to 2 mm long.
ges using the processing image software Calyx cup-shaped, 2-2.5 x 1.8-2 mm
ImageTool 5.0. wide, calyx-teeth widely deltoid, acute to
subobtuse. Corolla yellow, the standard
stripped brownish red; limb of standard RESULTS
ovate to somewhat orbicular, 3-5 x 2.5-5
Coronilla montserratii P. Fraga & Ros- mm, apex rounded or subacute, base na-
selló, sp. nov. (Fig. 1) rrowed suddenly to a claw 2-2.5 mm long;
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Flora Montiberica 46: 19-26 (X-2010). ISSN1138-5925 P. FRAGA & J.A. ROSSELLÓ
limb of wings obliquely oblong, concave, Menorca, 23 Jun 2001 P. Fraga (VAL,
up to 5 x 2.5 mm, equaling or slightly Herb. P. Fraga).
shorter than the standard, apex rounded, Etymology. The species is named after
base abruptly narrowed, auricula small Pedro Montserrat, a Spanish botanist that
and irregular, conjunctival tooth small or first collected the species and made
wanting, claw 2-2.5 mm long; limb of substantial contributions to the Balearic
keel crescent-shaped, narrow, up to 5 x flora.
1.5 mm, apex obtuse, claw 2-2.5 mm Distribution. Currently, Coronilla
long. Stamens 10, all united, 5-6 mm montserratii is only known from the
long, connate for up to 4 mm, anthers ba- western half of Minorca.
sifixed, oblong, about 0.3 x 0.1 mm. Habitat. Usually, this species grows at
Ovary linear, compressed, 3.5-4 x 0.4-0.5 low altitudes (between 5 and 80 m), on
mm, style 2-2.5 mm long, tapering to- sandy soils derived from the inland mi-
wards the apex, stigma small, terminal, gration of coastal dune systems. In fact,
capitate. Pod linear, much curved down- its known distribution area is mostly coin-
wards, 2-5 x 0.25-0.4 cm, glabrous, cident with the relevant dune formations
prominently articulated, and conspicuous- in the island. However, a large extent of
ly narrowed between the articulations, potentially suitable soils is currently dedi-
dorsal and ventral sutures apparent, apex cated to the agriculture or sand extraction.
acute to shortly rostrate; seeds sausage- In these areas the plant is rarely found or
shaped, slightly curved, 3-4 x 1-2 mm; appears only in less altered spots like bor-
testa grayish-brown, minutely verrucose. ders or outcrops. Coronilla montserratii
Flowering season starts in early April and, appears in open and sunny spots where
with favorable climatic conditions, lasts the sand is completely fixed or just sligh-
until end of June. tly mobile, but with a significant content
of organic matter. Here, it grows with
Representative specimens examined. other species like the perennial Aetheor-
MINORCA: 31SEE8021, Cala Macare- rhiza bulbosa (L.) Cass. subsp. bulbosa,
lla, Ciutadella de Menorca, 10-V-1959, P. and the terophytes Avellinia michelii (Sa-
Montserrat, (BC); 31SEE7921, Arenal de vi) Parl., Cerastium semidecandrum L.,
Macarelleta, Ciutadella de Menorca, 31- Desmazeria rigida (L.) Tutin, Lagurus
III-1996, P. Fraga (VAL, Herb. P. Fra- ovatus L., Lobularia maritima (L.) Desv.,
ga); 31SEE7620, Arenal de Son Saura, Lotus cytisoides L., Malcolmia ramosis-
Ciutadella de Menorca, 3-IV-1999, P. sima (Desf.) Thell., Medicago littoralis
Fraga (VAL, Herb. P. Fraga); 31TEE Rohde ex Loisel., Myosotis arvensis (L.)
8333, Al Pilar, Ciutadella de Menorca, Hill, Polycarpon tetraphyllum (L.) L.,
25-IV- 1999, P. Fraga (VAL, Herb. P. Rumex bucephalophorus L., Senecio vul-
Fraga); 31TEE7729, Ses Arenes, Ciutade- garis L., Vulpia ciliata Dumort., and V.
lla de Menorca, 19-V-2000, P. Fraga muralis (Kunth) Nees, among others. The
(VAL, Herb. P. Fraga); 31TEE7731, Bini- related C. scorpioides and C. montserratii
gafull, Ciutadella de Menorca, 6-V-2000, grow together at several sites. Usually, the
P. Fraga (VAL, Herb. P. Fraga); 31SEE populations of C. montserratii show scat-
7619, Arenal de Son Saura, Ciutadella de tered, isolated individuals extending over
Menorca, 31-III-2001, P. Fraga (VAL, large sandy areas. Dense populations have
Herb. P. Fraga); 31TEE8332, Alzinar not been observed.
d’Alforí, Ciutadella de Menorca, 1-V- Comparative morphology. A summa-
2001, P. Fraga (VAL, Herb. P. Fraga); ry of the morphological features used to
31TEE7832, Algaiarens, Ciutadella de discriminate annual species of Coronilla
is shown in Table 1 and a representative
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Flora Montiberica 46: 19-26 (X-2010). ISSN 1138-5925 Coronilla montserratii, a new species from Minorca
specimen of each species is depicted in soil, 18-V- 2008, P. Fraga, VAL; Minor-
Figure 3. Coronilla montserratii is related ca, 31SEE8918, Talis, cultivated fields,
to C. repanda but it is consistently more calcareous stony soil, 18-V-2008, P. Fra-
vigorous, showing longer and stout stems, ga, VAL) showed 2n=12. The other
and longer and wider dimensions in most annual species of Coronilla are diploid
of the leaf, leaflet, and legume features (2n=12; C. dura and C. scorpioides; FER-
(Table 1). These quantitative differences NANDES & SANTOS, 1971; FERNAN-
are likely related to the different ploidy DES & al. 1977) or tetraploid (2n=24; C.
level shown by both species (hexaploid repanda, FERNANDES & al. 1977). Pre-
and tetraploid, see below). In addition, viously, the hexaploid cytotype was only
they differs by the lower number of leaf- known from the perennial C. minima
lets in the upper leaves, the heteromorphic subsp. lotoides (KÜPFER, 1972).
shape of terminal and apical leaflets, as
well as leaflet shape (Table 1; Fig. 4). Co- DISCUSSION
ronilla repanda shows leaves with homo-
Coronilla montserratii shows the grea-morphic leaflets, which are narrowly ob-
test morphological similarities with C. re-lanceolate to elliptical and with rounded
panda but clearly differs by the lower and obtuse apices. Coronilla montserratii
number of leaflets in the upper leaves, the has contrasting leaves: the leaflets are he-
heteromorphic shape of terminal and api-teromorphic, the terminal being triangu-
cal leaflets as well as leaflet shape (Table lar-obovate (similar to the shape shown
1). These differences alone although cons-by C. dura), and the laterals, except the
tant could hardly justify its distinction as basal pair, are obovate with obtuse and
a new species, and the Minorcan popula-mucronate apices. The number of leaflets
tions could be better accommodated as a in the upper leaves also differentiate the
local race at any infraspecific rank, as has pair C. dura and C. repanda (leaves with
been done in the past (BOLÒS & VIGO, 7-9 leaflets) from C. montserratii that
1974) or, simply, subsumed under C. re-consistently show leaves with up to (3)5
panda (GARCÍA MARTÍN & TALAVE-leaflets. No obvious morphological fea-
RA, 2000). ture relates C. montserratii with C. scor-
However, the analysis of karyological pioides.
and unpublished molecular data points to Karyology. Individuals of C. montse-
more complex evolutionary scenarios sup-rratii from two populations (Minorca,
porting the specific status for C. montse-31TEE8332, Alzinar d’Alforí, calcareous
rratii. This species is a highly polyploid scrub, 7-VI-2004, P. Fraga, VAL; Minor-
(hexaploid) showing a chromosome num-ca, 31SEE7921, Macarelleta, fixed calca-
ber (2n=36) not shared by C. repanda reous sand dunes with low scrub vegeta-
(2n=24, tetraploid) and either C. dura and tion, 7-VI-2004, P. Fraga, VAL) have
C. scorpioides (2n=12, diploids). shown a constant somatic number of 2n =
On a theoretical basis, the hexaploid 36 chromosomes (Fig. 5). The chromoso-
level could have originated in C. montse-me complement of C. montserratii com-
rratii by autopolyploidy from either 2n= prises small metacentric chromoso-mes
24 and 2n=12 ancestors through fertiliza-(2-4.5 µm) similar in size. On the basis of
tion of reduced and unreduced gametes. the available cytogenetic knowledge in
However, invoking an origin from 2n=12 Coronilla suggesting a basic chromosome
progenitors is less parsimonious than number of x = 6, our re-sults imply that
from tetraploid ones since it requires the the new species is hexaploid. The two ac-
formation of viable triploid intermediates cessions of C. scorpioides from Minorca
(2n=18) before chromosome doubling. (Minorca, 31TEE8333, Al Pilar, sandy
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Flora Montiberica 46: 19-26 (X-2010). ISSN1138-5925 P. FRAGA & J.A. ROSSELLÓ
On the basis of the strong morpholo- convergence or to the retention of plesio-
gical similarity usually displayed by di- morphic features, tentatively suggests that
ploid and autopolyploid cytotypes and the a C. repanda-like ancestor could be the
fact that most differences, when present, tetraploid parent.
relate to quantitative rather than qualitati-
ve traits (SOLTIS & al., 2007; MAN- ACKNOWLEDGEMENTS: We thank G.
DÁKOVÁ & MÜNZBERGOVÁ, 2008), Nieto Feliner for constant advice and useful
comments on the manuscript and Dr Duncan data from morphology clearly exclude the
Ackery for linguistic advice. M. Castro, M. diploids C. dura and C. scorpioides, but
Rosato and A. Molins helped with the cyto-not the tetraploid C. repanda, as likely pa-
genetic and molecular work. This work has rents of an hypothetical autopolyploid C.
been partially funded by the CGL2007-60550/
montserratii. Further, phylogenetic analy- BOS project.
ses of nuclear ribosomal ITS sequences
(unpublished data) strongly suggest that
REFERENCES C. repanda and C. montserratii are not
sister taxa. Thus, available data do not
BALL, P.W. (1968) Coronilla. In TUTIN, T. support the hypothesis of an autopoly-
G. & al., (eds.): Flora Europaea, 2: 182-ploid origin of C. montserratii from ex-
184. Cambridge Univ. Press. Cambridge.
tant relatives.
BOLÒS, O. & J. VIGO (1974) Notes sobre ta-
The most parsimonious allopolyploid xonomia i nomenclatura de plantes, I. Butll.
hypothesis for C. montserratii should Inst. Catalana Hist. Nat. 38: 61-89.
involve an origin from tetraploid and FERNANDES, A. & M.F. SANTOS (1971,
diploid ancestors. The close morphology 1977) Contribution à la connaissance cyto-
taxinomique de spermatophyta de Portugal. shared by C. repanda and C. montserratii
IV. Leguminosae. Bol. Soc. Brot., ser. 2, 45: would support the former as a likely
177-225; 51: 137-186. tetraploid progenitor of the latter. On the
GARCÍA MARTÍN, F. & S. TALAVERA other hand, ribosomal nuclear ITS se-
(2000) Coronilla. In S. TALAVERA & al.
quences (unpublished data) strongly sug- (eds.): Flora iberica, 7 (2): 881-891. Real
gest that C. scorpioides was clearly invol- Jardín Botánico-CSIC. Madrid
ved in its origin and could be the diploid HOLMGREM, P.K., N.H. HOLMGREM, &
ancestor. L.C. BARNETT (1990) Index Herbariorum.
The fact that morphological features Part I: The herbaria of the world. 8th ed.
New York Botanical Garden. Bronx. USA. shown by C. montserratii are not midway
KÜPFER, P. (1972) Cytotaxonomie et cyto-between its proposed parental species or
géographie de quelques groupes d’orophytes showed sorted discriminating features, but
du bassin occidental de la Méditerranée et are biased towards a single progenitor (C.
des Alpes. Compt. Rend. Acad. Sci. Paris
repanda), could be explained by its higher
275: 1753-1756.
genomic contribution (four haploid geno- MANDÁKOVÁ, T. & Z. MÜNZBERGOVÁ
mes) than C. scorpioides (two haploid ge- (2008) Morphometric and genetic differen-
nomes) to its genesis. tiation of diploid and hexaploid populations
In conclusion, available evidence best of Aster amellus agg. in a contact zone. Pl.
Syst. Evolution 274: 155-170. fits an allopolyploid origin for C. montse-
SOLTIS, D.E. & al (2007) Autopolyploidy in rratii and molecular data identifies the di-
angiosperms: have we grossly underestima-ploid C. scorpioides as a likely proge-
ted the number of species? Taxon 56: 13-30. nitor. The identity of the second species
UHROVÁ, A. (1935) Revision der Gattung
involved in its origin remains elusive with Coronilla. Beih. Bot. Centralblatt 53 (1-3):
the use of molecular markers. However, 1-174.
the close morphology shared between C. (Recibido el 24-V-2010)
montserratii and C. repanda, if not due to
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Flora Montiberica 46: 19-26 (X-2010). ISSN 1138-5925 Coronilla montserratii, a new species from Minorca

Fig. 1. Habit of C. montserratii, including details of flowers (A, B) and fruits (C).
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Flora Montiberica 46: 19-26 (X-2010). ISSN1138-5925 P. FRAGA & J.A. ROSSELLÓ

Fig. 2. Representative specimens of annual species of Coronilla. (A) C.
montserratii (Minorca, Arenal de Macarelleta, VAL 190331, holotypus); (B) C.
repanda (Portugal, Torrao, SALA 42045); (C) C. dura (Spain, Arapiles, SALA
33906); (D) C. scorpioides (Spain, Usagre, SALA 3792).

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Flora Montiberica 46: 19-26 (X-2010). ISSN 1138-5925 Coronilla montserratii, a new species from Minorca
C.
C. montserratii C. repanda C. dura
scorpioides
Number of leaflets
5 7-9 7-9 3
(upper leaves)
Length of the
1.5-2 1 – 1.8 0.4-1.5 0.6 – 4.5
terminal leaflet (cm)
Length of basal
0.5-1 0.4 – 0.8 0.2-0.7 0.1 - 1.3
leaflets (cm)
Homomorphic.
Heteromorphic. Homomorphic. From
Obovate
Leaflet shape Terminal leaflet obova- narrowly Ovate, elliptic
triangular,
(terminal and te-triangular, truncate. oblanceolate to to nearly
truncate or
laterals) Lateral leaflets obovate, elliptical, apex orbicular
emarginate
obtuse, and mucronate rounded, obtuse

Calyx length (cm) 0.2–0.25 0.2–0.3 0.15-0.26 0.15 – 0.25
Corolla length (cm) 0.3–0.5 0.3-0.8 0.4-0.55 0.4 – 0.6
Legume width (cm) 0.25–0.4 0.15-0.2 0.15-0.25 0.2-0.3
Ploidy level 6x 4x 2x 2x
Table 1. Diagnostic morphological features between annual Coronilla species.




Fig. 3. Mitotic metaphase plate of C. montserratii (2n=36) from Alzinar d’Alforí.
Scale bar= 10 µm.


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Flora Montiberica 46: 19-26 (X-2010). ISSN1138-5925