Fraga i Arguimbau, Pere

Rosselló Picornell, Josep Antoni

Rosselló Picornell, Josep A.

Fraga Arguimbau, Pere

DIALNET

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

Repositori d'Objectes Digitals per a l'Ensenyament la Recerca i la Cultura

Flora Montiberica 46: 19-26 (X-2010) ISSN 1138-5925 19 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 legumes belonging to the tribe Loteae which shows a mainly Mediterranean dis-tribution with several species extending to northern European latitudes (UHROVÁ, 1935). The two annual species of Coro-nilla, C. repanda and C. scorpioides, have been included within sect. Scorpioides Bent. (UHROVÁ, 1935). A third entity, C. dura (Cav.) Boiss. is not unanimously recognized as a distinct species and has been usually included within C. repanda at the subspecific level (BALL, 1968; GARCÍA MARTÍN & TALAVERA, 2000). During field work aimed at increa-sing the floristic knowledge of the sandy areas of Minorca (Balearic Islands), we found several populations resembling C. repanda but showing a deviant morpho-logy concerning the shape of leaves and leaflets. In addition, cytogenetic studies revealed that the Minorcan plants were highly polyploid and differed from pre-vious chromosome numbers so far repor- ted in annual species of Coronilla. Coronilla montserratii, a new species from Minorca  Flora Montiberica 46: 19-26 (X-2010). ISSN1138-5925 20The combination of morphological characteristics of diagnostic value and ploidy level suggest that the plants from Minorca belong to an entity not previous-ly described, and it is presented in this paper as a new species.   MATERIALS AND METHODS  Plant material. Living material from C. repanda and C. scorpioides was collected from populations across Minorca. Vou-cher specimens are preserved at VAL. Morphological observations were based on living material examined in the field and herbarium specimens from the her-baria BC, MA, VAL (abbreviations accor-ding to HOLMGREM & al. 1990). Chromosome preparations. Seeds were germinated on solid agar in Petri dishes in a constant temperature of 20ºC and 12 hours of white light daily. Root tips were pre-treated with 0.05% colchicine solu-tion at room temperature for 2-3 hours, washed with distilled water, fixed in fresh Carnoy I solution overnight and stored in 70% ethanol at 4ºC until used. For chro-mosome counts root tips were hydrolysed for 5-10 min in 1M HCl at 60ºC, and washed and stained in Feulgen solution for 1-2 h. Stained meristems were squa-shed in a drop of 45% acetic acid and permanent preparations were made by mounting in Canada balsam. Photomicro-graphs of well-spread metaphases were taken with an Olympus Camedia C-2000-Z digital camera and processed with Ado-be Photoshop 7.0. Chromosome counts were made from at least five well-spread metaphases by direct observation and from the photomicrographs. Chromosome measurements were made on digital ima-ges using the processing image software ImageTool 5.0.   RESULTS  Coronilla montserratii P. Fraga & Ros- selló, sp. nov. (Fig. 1)  Diagnosis: A Coronilla repanda simi-lis, sed robustior, foliolis longiores et la-tiores, foliae composita cum foliolis hete-romorphi, legumina latiores et robustior, et chromosomatum numerum (2n=36) dif-fert. Holotype: SPAIN: Balearic Islands. Mi-norca: Arenal de Macarelleta, Ciutadella de Menorca (31SEE7921), fixed calcareous sand dunes with low scrub, 20 m, 31-03- 1996, P. Fraga (VAL 190331). Isotype: herbarium P. Fraga.  Description: Ascending or erect, gla-brous, glaucous annual. Stem 10-40 cm long, subterete or obscurely angled, bran-ched from the base and upwards. Leaves slightly fleshy, heteromorphic. Basal lea-ves simple, unifoliate, petiolate, oblong, 0.5-3.5 cm long, 0.3-2.8 cm wide, apex rounded or truncate, base broadly cuneate, border entire. Medium leaves, petiolate, 3-7 foliolate. Leaflets heteromorphic, the terminal 0.7-2 x 0.4-1.4 cm, longer than the lateral ones, apex usually emargina-ted, mucronate, base narrowly cuneate, border entire; lateral leaflets orbicular to obovate, 0.5-1.5 x 0.3-1.2 cm, the lower pair bigger than the apical one, apex roun-ded, mucronate, base rounded to broadly cuneate, border entire; basal leaflets clear-ly distinct, obcordate to ear shaped, 0.2-1.2 x 0.15-0.8 cm wide, apex obtuse to emarginate, sometimes mucronate. Upper leaves with up to five leaflets, heteromor-phic; stipules connate, 1.5-3 mm long, al-most as long as wide, membranous, apex clearly bifid, teeth sometimes acuminate. Inflorescences 2-5 flowered, arising from the axils of the upper leaves. Peduncles 1-4 cm long, exceeding the subtending leaf and lengthening in fruit; bracts connate, up to 1 mm long, deltoid, membranous; pedicels short, curved, up to 2 mm long. Calyx cup-shaped, 2-2.5 x 1.8-2 mm wide, calyx-teeth widely deltoid, acute to subobtuse. Corolla yellow, the standard stripped brownish red; limb of standard ovate to somewhat orbicular, 3-5 x 2.5-5 mm, apex rounded or subacute, base na-rrowed suddenly to a claw 2-2.5 mm long; P. FRAGA & J.A. ROSSELLÓ  Flora Montiberica 46: 19-26 (X-2010). ISSN 1138-5925 21limb of wings obliquely oblong, concave, up to 5 x 2.5 mm, equaling or slightly shorter than the standard, apex rounded, base abruptly narrowed, auricula small and irregular, conjunctival tooth small or wanting, claw 2-2.5 mm long; limb of keel crescent-shaped, narrow, up to 5 x 1.5 mm, apex obtuse, claw 2-2.5 mm long. Stamens 10, all united, 5-6 mm long, connate for up to 4 mm, anthers ba-sifixed, oblong, about 0.3 x 0.1 mm. Ovary linear, compressed, 3.5-4 x 0.4-0.5 mm, style 2-2.5 mm long, tapering to-wards the apex, stigma small, terminal, capitate. Pod linear, much curved down-wards, 2-5 x 0.25-0.4 cm, glabrous, prominently articulated, and conspicuous-ly narrowed between the articulations, dorsal and ventral sutures apparent, apex acute to shortly rostrate; seeds sausage-shaped, slightly curved, 3-4 x 1-2 mm; testa grayish-brown, minutely verrucose. Flowering season starts in early April and, with favorable climatic conditions, lasts until end of June.  Representative specimens examined. MINORCA: 31SEE8021, Cala Macare-lla, Ciutadella de Menorca, 10-V-1959, P. Montserrat, (BC); 31SEE7921, Arenal de Macarelleta, Ciutadella de Menorca, 31-III-1996, P. Fraga (VAL, Herb. P. Fra-ga); 31SEE7620, Arenal de Son Saura, Ciutadella de Menorca, 3-IV-1999, P. Fraga (VAL, Herb. P. Fraga); 31TEE 8333, Al Pilar, Ciutadella de Menorca, 25-IV- 1999, P. Fraga (VAL, Herb. P. Fraga); 31TEE7729, Ses Arenes, Ciutade-lla de Menorca, 19-V-2000, P. Fraga (VAL, Herb. P. Fraga); 31TEE7731, Bini-gafull, Ciutadella de Menorca, 6-V-2000, P. Fraga (VAL, Herb. P. Fraga); 31SEE 7619, Arenal de Son Saura, Ciutadella de Menorca, 31-III-2001, P. Fraga (VAL, Herb. P. Fraga); 31TEE8332, Alzinar d’Alforí, Ciutadella de Menorca, 1-V-2001, P. Fraga (VAL, Herb. P. Fraga); 31TEE7832, Algaiarens, Ciutadella de Menorca, 23 Jun 2001 P. Fraga (VAL, Herb. P. Fraga). Etymology. The species is named after Pedro Montserrat, a Spanish botanist that first collected the species and made substantial contributions to the Balearic flora. Distribution. Currently, Coronilla montserratii is only known from the western half of Minorca.  Habitat. Usually, this species grows at low altitudes (between 5 and 80 m), on sandy soils derived from the inland mi-gration of coastal dune systems. In fact, its known distribution area is mostly coin-cident with the relevant dune formations in the island. However, a large extent of potentially suitable soils is currently dedi-cated to the agriculture or sand extraction. In these areas the plant is rarely found or appears only in less altered spots like bor-ders or outcrops. Coronilla montserratii appears in open and sunny spots where the sand is completely fixed or just sligh-tly mobile, but with a significant content of organic matter. Here, it grows with other species like the perennial Aetheor-rhiza bulbosa (L.) Cass. subsp. bulbosa, and the terophytes Avellinia michelii (Sa-vi) Parl., Cerastium semidecandrum L., Desmazeria rigida (L.) Tutin, Lagurus ovatus L., Lobularia maritima (L.) Desv., Lotus cytisoides L., Malcolmia ramosis-sima (Desf.) Thell., Medicago littoralis Rohde ex Loisel., Myosotis arvensis (L.) Hill, Polycarpon tetraphyllum (L.) L., Rumex bucephalophorus L., Senecio vul-garis L., Vulpia ciliata Dumort., and V. muralis (Kunth) Nees, among others. The related C. scorpioides and C. montserratii grow together at several sites. Usually, the populations of C. montserratii show scat-tered, isolated individuals extending over large sandy areas. Dense populations have not been observed.  Comparative morphology. A summa-ry of the morphological features used to discriminate annual species of Coronilla is shown in Table 1 and a representative Coronilla montserratii, a new species from Minorca  Flora Montiberica 46: 19-26 (X-2010). ISSN1138-5925 22specimen of each species is depicted in Figure 3. Coronilla montserratii is related to C. repanda but it is consistently more vigorous, showing longer and stout stems, and longer and wider dimensions in most of the leaf, leaflet, and legume features (Table 1). These quantitative differences are likely related to the different ploidy level shown by both species (hexaploid and tetraploid, see below). In addition, they differs by the lower number of leaf-lets in the upper leaves, the heteromorphic shape of terminal and apical leaflets, as well as leaflet shape (Table 1; Fig. 4). Co-ronilla repanda shows leaves with homo-morphic leaflets, which are narrowly ob-lanceolate to elliptical and with rounded and obtuse apices. Coronilla montserratii has contrasting leaves: the leaflets are he-teromorphic, the terminal being triangu-lar-obovate (similar to the shape shown by C. dura), and the laterals, except the basal pair, are obovate with obtuse and mucronate apices. The number of leaflets in the upper leaves also differentiate the pair C. dura and C. repanda (leaves with 7-9 leaflets) from C. montserratii that consistently show leaves with up to (3)5 leaflets. No obvious morphological fea-ture relates C. montserratii with C. scor-pioides. Karyology. Individuals of C. montse-rratii from two populations (Minorca, 31TEE8332, Alzinar d’Alforí, calcareous scrub, 7-VI-2004, P. Fraga, VAL; Minor-ca, 31SEE7921, Macarelleta, fixed calca-reous sand dunes with low scrub vegeta-tion, 7-VI-2004, P. Fraga, VAL) have shown a constant somatic number of 2n = 36 chromosomes (Fig. 5). The chromoso-me complement of C. montserratii com-prises small metacentric chromoso-mes (2-4.5 µm) similar in size. On the basis of the available cytogenetic knowledge in Coronilla suggesting a basic chromosome number of x = 6, our re-sults imply that the new species is hexaploid. The two ac-cessions of C. scorpioides from Minorca (Minorca, 31TEE8333, Al Pilar, sandy soil, 18-V- 2008, P. Fraga, VAL; Minor-ca, 31SEE8918, Talis, cultivated fields, calcareous stony soil, 18-V-2008, P. Fra-ga, VAL) showed 2n=12. The other annual species of Coronilla are diploid (2n=12; C. dura and C. scorpioides; FER-NANDES & SANTOS, 1971; FERNAN-DES & al. 1977) or tetraploid (2n=24; C. repanda, FERNANDES & al. 1977). Pre-viously, the hexaploid cytotype was only known from the perennial C. minima subsp. lotoides (KÜPFER, 1972).  DISCUSSION  Coronilla montserratii shows the grea-test morphological similarities with C. re-panda but clearly differs by the lower number of leaflets in the upper leaves, the heteromorphic shape of terminal and api-cal leaflets as well as leaflet shape (Table 1). These differences alone although cons-tant could hardly justify its distinction as a new species, and the Minorcan popula-tions could be better accommodated as a local race at any infraspecific rank, as has been done in the past (BOLÒS & VIGO, 1974) or, simply, subsumed under C. re-panda (GARCÍA MARTÍN & TALAVE-RA, 2000).  However, the analysis of karyological and unpublished molecular data points to more complex evolutionary scenarios sup-porting the specific status for C. montse-rratii. This species is a highly polyploid (hexaploid) showing a chromosome num-ber (2n=36) not shared by C. repanda (2n=24, tetraploid) and either C. dura and C. scorpioides (2n=12, diploids).  On a theoretical basis, the hexaploid level could have originated in C. montse-rratii by autopolyploidy from either 2n= 24 and 2n=12 ancestors through fertiliza-tion of reduced and unreduced gametes. However, invoking an origin from 2n=12 progenitors is less parsimonious than from tetraploid ones since it requires the formation of viable triploid intermediates  (2n=18) before chromosome doubling.  P. FRAGA & J.A. ROSSELLÓ  Flora Montiberica 46: 19-26 (X-2010). ISSN 1138-5925 23On the basis of the strong morpholo-gical similarity usually displayed by di-ploid and autopolyploid cytotypes and the fact that most differences, when present, relate to quantitative rather than qualitati-ve traits (SOLTIS & al., 2007; MAN-DÁKOVÁ & MÜNZBERGOVÁ, 2008), data from morphology clearly exclude the diploids C. dura and C. scorpioides, but not the tetraploid C. repanda, as likely pa-rents of an hypothetical autopolyploid C. montserratii. Further, phylogenetic analy-ses of nuclear ribosomal ITS sequences (unpublished data) strongly suggest that C. repanda and C. montserratii are not sister taxa. Thus, available data do not support the hypothesis of an autopoly-ploid origin of C. montserratii from ex-tant relatives.  The most parsimonious allopolyploid hypothesis for C. montserratii should involve an origin from tetraploid and diploid ancestors. The close morphology shared by C. repanda and C. montserratii would support the former as a likely tetraploid progenitor of the latter. On the other hand, ribosomal nuclear ITS se-quences (unpublished data) strongly sug-gest that C. scorpioides was clearly invol-ved in its origin and could be the diploid ancestor.  The fact that morphological features shown by C. montserratii are not midway between its proposed parental species or showed sorted discriminating features, but are biased towards a single progenitor (C. repanda), could be explained by its higher genomic contribution (four haploid geno-mes) than C. scorpioides (two haploid ge-nomes) to its genesis.  In conclusion, available evidence best fits an allopolyploid origin for C. montse-rratii and molecular data identifies the di-ploid C. scorpioides as a likely proge-nitor. The identity of the second species involved in its origin remains elusive with the use of molecular markers. However, the close morphology shared between C. montserratii and C. repanda, if not due to convergence or to the retention of plesio-morphic features, tentatively suggests that a C. repanda-like ancestor could be the tetraploid parent.    ACKNOWLEDGEMENTS: We thank G. Nieto Feliner for constant advice and useful comments on the manuscript and Dr Duncan Ackery for linguistic advice. M. Castro, M. Rosato and A. Molins helped with the cyto-genetic and molecular work. This work has been partially funded by the CGL2007-60550/ BOS project.   REFERENCES  BALL, P.W. (1968) Coronilla. In TUTIN, T. G. & al., (eds.): Flora Europaea, 2: 182-184. Cambridge Univ. Press. Cambridge.  BOLÒS, O. & J. VIGO (1974) Notes sobre ta-xonomia i nomenclatura de plantes, I. Butll. Inst. Catalana Hist. Nat. 38: 61-89. FERNANDES, A. & M.F. SANTOS (1971, 1977) Contribution à la connaissance cyto-taxinomique de spermatophyta de Portugal. IV. Leguminosae. Bol. Soc. Brot., ser. 2, 45: 177-225; 51: 137-186. GARCÍA MARTÍN, F. & S. TALAVERA (2000) Coronilla. In S. TALAVERA & al. (eds.): Flora iberica, 7 (2): 881-891. Real Jardín Botánico-CSIC. Madrid HOLMGREM, P.K., N.H. HOLMGREM, & L.C. BARNETT (1990) Index Herbariorum. Part I: The herbaria of the world. 8th ed. New York Botanical Garden. Bronx. USA. KÜPFER, P. (1972) Cytotaxonomie et cyto-géographie de quelques groupes d’orophytes du bassin occidental de la Méditerranée et des Alpes. Compt. Rend. Acad. Sci. Paris 275: 1753-1756. MANDÁKOVÁ, T. & Z. MÜNZBERGOVÁ (2008) Morphometric and genetic differen-tiation of diploid and hexaploid populations of Aster amellus agg. in a contact zone. Pl. Syst. Evolution 274: 155-170.  SOLTIS, D.E. & al (2007) Autopolyploidy in angiosperms: have we grossly underestima-ted the number of species? Taxon 56: 13-30. UHROVÁ, A. (1935) Revision der Gattung Coronilla. Beih. Bot. Centralblatt 53 (1-3): 1-174. (Recibido el 24-V-2010) Coronilla montserratii, a new species from Minorca  Flora Montiberica 46: 19-26 (X-2010). ISSN1138-5925 24 Fig. 1. Habit of C. montserratii, including details of flowers (A, B) and fruits (C). P. FRAGA & J.A. ROSSELLÓ  Flora Montiberica 46: 19-26 (X-2010). ISSN 1138-5925 25 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).  Coronilla montserratii, a new species from Minorca  Flora Montiberica 46: 19-26 (X-2010). ISSN1138-5925 26Table 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.    C. montserratii C. repanda C. dura C. scorpioides Number of leaflets (upper leaves) 5 7-9 7-9 3 Length of the terminal leaflet (cm) 1.5-2 1 – 1.8 0.4-1.5 0.6 – 4.5 Length of basal leaflets (cm) 0.5-1 0.4 – 0.8 0.2-0.7 0.1 - 1.3 Leaflet shape (terminal and laterals) Heteromorphic. Terminal leaflet obova-te-triangular, truncate. Lateral leaflets obovate, obtuse, and mucronate Homomorphic. From narrowly oblanceolate to elliptical, apex rounded, obtuse Homomorphic. Obovate triangular, truncate or emarginate  Ovate, elliptic to nearly orbicular 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 

http://hispana.mcu.es/es/registros/registro.do?tipoRegistro=MTD&idBib=5664999

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

Abstract

Similar works

Full text

Available Versions

DIALNET

Repositori d'Objectes Digitals per a l'Ensenyament la Recerca i la Cultura