ARTÍCULO

Typification of two names in the genus Asperula (Rubiaceae)

P. P. FERRER-GALLEGO1,2 & E. LAGUNA2

1 Servicio de Vida Silvestre, Centro para la Investigación y Experimentación Forestal de la Generalitat Valenciana (CIEF), av. Comarques del País Valencià, 114, ES-46930 Quart de Poblet, València, Spain

2 VAERSA, av. de les Corts Valencianes, 20, ES-46015 València, Spain

 

ORCID iD. P. P. FERRER-GALLEGO: http://orcid.org/0000-0001-7595-9302, E. LAGUNA: http://orcid.org/0000-0002-9674-2767

 

Author for correspondence: P. P. Ferrer-Gallego (flora.cief@gva.es)

 

Editor: L. Sáez

Typification of two names in the genus Asperula (Rubiaceae)

ABSTRACT
Typification of two names in the genus Asperula (Rubiaceae).— The typification of two names in the genus Asperula, A. cynanchica subsp. pyrenaica and A. paui subsp. dianensis (Rubiaceae), applicable to species endemic to the Iberian Peninsula and France, is discussed. Specimens from UPS (Herbarium Burser, Uppsala University) and BC (Institut Botànic of Barcelona) are indicated and designated as lectotypes of, respectively, A. pyrenaica and A. paui var. dianensis.
KEY WORDS: Asperula; lectotypification; Linnaeus; nomenclature.

Tipificación de dos nombres en el género Asperula (Rubiaceae)

RESUMEN
Tipificación de dos nombres en el género Asperula (Rubiaceae).— Se discute la tipificación de dos nombres en el género Asperula, A. cynanchica subsp. pyrenaica y A. paui subsp. dianensis (Rubiaceae) aplicables a especies endémicas de la Península Ibérica y Francia. Especímenes de UPS (Herbario Burser, Universidad de Uppsala) y BC (Institut Botànic de Barcelona) son indicados y designados como lectotipos de A. pyrenaica and A. paui var. dianensis, respectivamente.
PALABRAS CLAVE: Asperula; lectotipificación; Linneo; nomenclatura.

Received: 24/11/2017 / Accepted: 20/12/2017 / Published on line: 28/08/2018

Cómo citar este artículo / Citation: Ferrer-Gallego, P. P. & Laguna, E. 2018. Typification of two names in the genus Asperula (Rubiaceae). Collectanea Botanica 37: e008. https://doi.org/10.3989/collectbot.2018.v37.008

Copyright: © 2018 CSIC. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License.

CONTENIDOS

ABSTRACT
RESUMEN
INTRODUCTION
MATERIALS AND METHODS
TYPIFICATION OF THE NAMES
ACKNOWLEDGEMENTS
NOTES
REFERENCES

INTRODUCTIONTop

Asperula L. (Rubieae Baill., Rubiaceae Juss.) includes approximately 130 species classified into 10 sections (Ehrendorfer et al., 2005Ehrendorfer, F., Schönbeck-Temesy, E., Puff, C. & Rechinger, W. 2005. Rubiaceae. In: Rechinger, K. H. (Ed.), Flora Iranica 176. Verlag des Naturhistorischen Museums Wien, Vienna.). The genus shows a high morphological and karyological variability and it is critical from the taxonomic point of view (Del Guacchio & Caputo, 2005Del Guacchio, E. & Caputo, P. 2005. Taxonomic notes on Asperula neglecta Guss. and Asperula nitens Guss. (Rubiaceae), and typification of their names. Webbia 60: 569–576. https://doi.org/10.1080/00837792.2005.10670787, 2013Del Guacchio, E. & Caputo, P. 2013. Taxonomic notes on Asperula sect. Cynanchica (Rubiaceae). Taxon 62: 394–400. http://doi.org/10.12705/622.9 ; Minareci & Yıldız, 2011Minareci, E. & Yıldız, K. 2011. Karyotype characterization of Turkish taxa of the genus Asperula L.- section Thlipthisa (Rubiaceae). Indian Journal of Genetics and Plant Breeding 71: 49–54.; Gargiulo et al., 2015Gargiulo, R., Del Guacchio, E. & Caputo, P. 2015. Phylogenetic reconstruction of Asperula sect. Cynanchicae (Rubiaceae) reveals a mosaic of evolutionary histories. Taxon 64: 754–769. https://doi.org/10.12705/644.7). Asperula sect. Cynanchicae (DC.) Boiss. comprises about 100 mainly locally endemic taxa, which are dwarf shrubs or herbaceous perennials, growing on dry and rocky ground, with a preference for calcareous substrates. The section is predominantly distributed in the Mediterranean and Aegean areas, but its range extends to Great Britain in the north and Central Asia in the east (Ehrendorfer & Krendl, 1976Ehrendorfer, F. & Krendl, F. 1976. Asperula L. In: Tutin, T. G., Burges, N. A., Chater, A. O., Edmondson, J. R., Heywood, V. H., Moore, T. M., Valentine, D. H., Walters, S. M. & Webb, D. A. (Eds.), Flora Europaea 3. Cambridge Unversity Press, Cambridge, London, New York & Melbourne: 4–9.; Ehrendorfer et al., 2014Ehrendorfer, F., Vladimirov, V. & Barfuss, M. H. J. 2014. Paraphyly and polyphyly in the worldwide tribe Rubieae (Rubiaceae): Challenges for generic delimitation. Annals of the Missouri Botanical Garden 100: 79–88. https://doi.org/10.3417/2012088). The type of the section is the very polymorphic A. cynanchica L. (Gargiulo et al., 2015Gargiulo, R., Del Guacchio, E. & Caputo, P. 2015. Phylogenetic reconstruction of Asperula sect. Cynanchicae (Rubiaceae) reveals a mosaic of evolutionary histories. Taxon 64: 754–769. https://doi.org/10.12705/644.7), and the lectotype of this name was designated by Ferrer-Gallego (2015Ferrer-Gallego, P. P. 2015. Typification of the Linnaean name Asperula cynanchica (Rubiaceae). Phytotaxa 195: 98–100. https://doi.org/10.11646/phytotaxa.195.1.10) on a specimen at UPS (Herb. Burser XIX: 8).

Typifications of several species of Asperula in this section have already been published (Rosselló & Sáez, 2000Rosselló, J. A. & Sáez, L. 2000. Index Balearicum: An annotated check-list of the vascular plants described from the Balearic Islands. Collectanea Botanica 25: 3–192.; Del Guacchio & Caputo, 2005Del Guacchio, E. & Caputo, P. 2005. Taxonomic notes on Asperula neglecta Guss. and Asperula nitens Guss. (Rubiaceae), and typification of their names. Webbia 60: 569–576. https://doi.org/10.1080/00837792.2005.10670787, 2013Del Guacchio, E. & Caputo, P. 2013. Taxonomic notes on Asperula sect. Cynanchica (Rubiaceae). Taxon 62: 394–400. http://doi.org/10.12705/622.9 ; Peruzzi et al., 2013Peruzzi, L., Santangelo, A. & Jarvis, C. E. 2013. Lectotypification of Linnaean names in the Italian endemic flora. Taxon 62: 827–829. https://doi.org/10.12705/624.27; Ferrer-Gallego, 2015Ferrer-Gallego, P. P. 2015. Typification of the Linnaean name Asperula cynanchica (Rubiaceae). Phytotaxa 195: 98–100. https://doi.org/10.11646/phytotaxa.195.1.10). However, the Linnaean name Asperula pyrenaica [currently accepted as A. cynanchica subsp. pyrenaica (L.) Nyman] and the name A. paui var. dianensis Font Quer [currently accepted as A. paui subsp. dianensis (Font Quer) Romo] (nomenclature according to Govaerts et al., 2012Govaerts, R., Ruhsam, M., Andersson, L. et al. 2012. World checklist of Rubiaceae. The Board of Trustees of the Royal Botanic Gardens, Kew.) have not been yet investigated (see e.g. Bolòs & Vigo, 1983Bolòs, O. & Vigo, J. 1983. Notes sobre taxonomia i nomenclatura de les plantes, II. Collectanea Botanica 14: 89–103.; De la Torre et al., 1996De la Torre, A., Alcaraz, F. & Crespo, M. B. 1996. Aproximación a la biogeografía del sector Setabense (provincia Catalano-Valenciano-Provenzal). Lazaroa 16: 141–158.; Jarvis, 2007Jarvis, C. E. 2007. Order out the chaos. Linnaean plant names and their types. The Linnean Society of London in association with the Natural History Museum, London.) and are here typified. The purpose of this paper is to contribute to stability of nomenclature by the typification of these two names.

MATERIALS AND METHODSTop

The designation of the corresponding types is based on the examination of Linnaeus’s and Font Quer’s original material and the literature cited in the respective protologues. The acronyms of the herbarium collections are cited according to Thiers (2017Thiers, B. 2017. Index Herbariorum: A global directory of public herbaria and associated staff. New York Botanical Garden’s Virtual Herbarium. Retrieved July, 2017, from https://www.nybg.org/science-project/index-herbariorum-upgrade). Authors of cited taxa follow IPNI (2017IPNI (The International Plant Names Index) 2017. Retrieved July, 2017, from http://www.ipni.org).

TYPIFICATION OF THE NAMESTop

Asperula pyrenaica

Asperula pyrenaica group is very variable with numerous local races (Ehrendorfer & Krendl, 1976Ehrendorfer, F. & Krendl, F. 1976. Asperula L. In: Tutin, T. G., Burges, N. A., Chater, A. O., Edmondson, J. R., Heywood, V. H., Moore, T. M., Valentine, D. H., Walters, S. M. & Webb, D. A. (Eds.), Flora Europaea 3. Cambridge Unversity Press, Cambridge, London, New York & Melbourne: 4–9.; Gargiulo et al., 2015Gargiulo, R., Del Guacchio, E. & Caputo, P. 2015. Phylogenetic reconstruction of Asperula sect. Cynanchicae (Rubiaceae) reveals a mosaic of evolutionary histories. Taxon 64: 754–769. https://doi.org/10.12705/644.7). Asperula cynanchica subsp. pyrenaica is a caespitose plant, with subterranean stolons, stems 2–20(–30) cm, weak, herbaceous throughout, stems usually shortly papillose-hairy below, often glabrescent above, lower leaves ovate or obovate, densely crowded, 8–16 × 0.3–1.3 mm, the margin weakly revolute, often shortly ciliate, bracts narrowly lanceolate, inflorescence corymbiform, corolla pink 2.8–4 mm, tube usually 1–1.5 times as long as lobes. This plant is distributed in upper montane to alpine zones in the Pyrenees (Spain and France) (Ortega-Olivencia & Devesa, 2007Ortega-Olivencia, A. & Devesa, J. A. 2007. Asperula L. In: Devesa, J. A., Gonzalo, R. & Herrero, A. (Eds.), Flora iberica 15. Real Jardín Botánico (CSIC), Madrid: 36–56.).

Linnaeus’s protologue (1753Linnaeus, C. 1753. Species plantarum. Impensis Laurentii Salvii, Stockholm. http://doi.org/10.5962/bhl.title.669: 104) consisted of a nomen specificum legitimum “ASPERULA foliis quaternis lanceolato-linearibus, caule erecto, floribus saepius trifidis”, followed by a synonym “Rubia cynanchica saxatilis”, cited from Bauhin (1620Bauhin, C. 1620. Prodromus theatri botanici. Typis Pauli Iacobi, impensis Ioannis Treudelii, Francofurti ad Moenum, 160 pp. Retrieved November, 2017, from http://bibdigital.rjb.csic.es/spa/Libro.php?Libro=1441&Hojas=: 146; 1623Bauhin, C. 1623. Pinax theatri botanici. Sumptibus & typis Ludovici Regis, Basileae.: 333) and the citation of a Burser specimen (“Burs. XIX. 9”). The provenance was also reported (“Habitat in Pyrenaeis versus Hispaniam & prope Valentiam Gallorum”). The protologue also includes the following description of the species: “Caules erecti, spithamaei, quadrangules. Folia omnia in caule quaterna, linearia, carinata, acuta, laevia; inferior etiam quaterna, sed breviora lanceolata obtusiora; folia summa & floralia opposita, latiora, acuta, lanceolata. Flores tubulosi, rubris, saepius trifidi”.

Jarvis (2007Jarvis, C. E. 2007. Order out the chaos. Linnaean plant names and their types. The Linnean Society of London in association with the Natural History Museum, London.: 326) cited as Linnaeus’s original material the specimen at Herb. Burser XIX: 9 (UPS) (see also Juel, 1923Juel, H. O. 1923. Studien in Burser’s Hortus siccus. Nova Acta Regiae Societatis Scientiarum Upsaliensis, ser. 4-5, 7: 1–144.; Savage, 1937Savage, S. 1937. Caroli Linnaei determinationes in Hortum Siccum Joachimi Burseri. The text of the manuscript in the Linnaean Collections. The Linnean Society, London.). This specimen was cited by Linnaeus in the protologue, and therefore could be considered as a syntype (see just below) according to the Art. 9.5 of the International Code of Nomenclature (McNeill et al., 2012McNeill, J., Barrie, F. R., Buck, W. R. et al. (Eds.) 2012. International Code of Nomenclature for algae, fungi, and plants (Melbourne Code) (Regnum Vegetabile, 154). Koeltz Scientific Books, Königstein.). The sheet at UPS-BURSER bears a well preserved flowering specimen, and the original annotation “Rubia cynanchica saxatilis Bauh. / In Pyrenaeis versus Hispaniam, et prope Valentiam Gallorum”. The UPS specimen morphologically matches the current concept and use of the name (e.g. Ehrendorfer & Krendl, 1976Ehrendorfer, F. & Krendl, F. 1976. Asperula L. In: Tutin, T. G., Burges, N. A., Chater, A. O., Edmondson, J. R., Heywood, V. H., Moore, T. M., Valentine, D. H., Walters, S. M. & Webb, D. A. (Eds.), Flora Europaea 3. Cambridge Unversity Press, Cambridge, London, New York & Melbourne: 4–9.; Bolòs & Vigo, 1996Bolòs, O. & Vigo, J. 1996. Flora dels Països Catalans 3. Editorial Barcino, Barcelona.; Ortega-Olivencia & Devesa, 2007Ortega-Olivencia, A. & Devesa, J. A. 2007. Asperula L. In: Devesa, J. A., Gonzalo, R. & Herrero, A. (Eds.), Flora iberica 15. Real Jardín Botánico (CSIC), Madrid: 36–56.; Aizpuru et al., 2015Aizpuru, I., Aseginolaza, C., Uribe-Echebarría, P. M., Urrutia, P. & Zorrakin, I. 2015. Claves ilustradas de la flora del País Vasco y territorios limítrofes (1ª ed., 4ª reimp.). Servicio Central de Publicaciones del Gobierno Vasco, Vitoria-Gasteiz.), and it is designated as the lectotype of the Linnaean name Asperula pyrenaica.

However, we consider important to mention that we have been unable to locate any further original material in any Linnaean or Linnaean-linked herbaria, and the specimen at UPS-BURSER appears to be the only extant useful material. In this sense, if the specimen at UPS is the only element used by Linnaeus, it must be accepted as the holotype (Art. 9 Note 1). Accordingly, as indicated McNeill (2014McNeill, J. 2014. Holotype specimens and type citations: General issues. Taxon 63: 1112–1113. https://doi.org/10.12705/635.7), the type can be indicated as: “Lectotype, designated here (or perhaps holotype)”.

Asperula cynanchica subsp. pyrenaica (L.) Nyman, Consp. Fl. Eur.: 333 (1879)

Asperula pyrenaica L., Sp. Pl.: 104 (1753Linnaeus, C. 1753. Species plantarum. Impensis Laurentii Salvii, Stockholm. http://doi.org/10.5962/bhl.title.669) [basionym].

Ind. loc.: “Habitat in Pyrenaeis versus Hispaniam & prope Valentiam Gallorum

Lectotype (designated here [or perhaps holotype]): Herb. Burser XIX: 9 (UPS-BURSER!). Fig. 1

Figure 1. Lectotype (or perhaps holotype) of Asperula pyrenaica L. (UPS, Herb. Burser XIX: 9). © Herbarium UPS, reproduced with permission.

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Asperula paui var. dianensis

Asperula paui subsp. dianensis is distributed only in the Alicante province (Spain), and it differs from the subspecies type (endemic to Western Balearic Islands) by the longer corolla, up to 4.2–7.7 mm (2.5–4.7 mm in subsp. paui), pink or yellow on the inner side of the lobes (pink or white in subsp. paui), longer style, up to 5.8 mm (up to 1.6 mm in subsp. paui), and stigmas reaching the upper level of the anthers (and not reaching the upper level of the anthers in subsp. paui) (Laguna et al., 1998Laguna, E., Crespo, M. B., Mateo, G. et al. 1998. Flora endémica, rara o amenazada de la Comunidad Valenciana. Consellería de Medio Ambiente, Valencia.; Ortega-Olivencia & Devesa, 2007Ortega-Olivencia, A. & Devesa, J. A. 2007. Asperula L. In: Devesa, J. A., Gonzalo, R. & Herrero, A. (Eds.), Flora iberica 15. Real Jardín Botánico (CSIC), Madrid: 36–56.).

The lectotype of A. paui was designated by Rosselló & Sáez (2000Rosselló, J. A. & Sáez, L. 2000. Index Balearicum: An annotated check-list of the vascular plants described from the Balearic Islands. Collectanea Botanica 25: 3–192.: 156) from a specimen at BC (barcode BC109680!) [the specimen was mounted on three herbarium sheets] from “Cala de les Torretes (Eivissa)” and collected by E. Gros on 8 July 1920, another original material is preserved at B, with barcode B 10 0278134!, collected on 9 July 1920 also by E. Gros in “Hispaniae: Ebuso” (image available at http://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen.b_10_0278134).

The protologue of A. paui var. dianensis (Font Quer, 1926: 57) includes a diagnosis (“A typo foliis angustioribus, corolla tubo elongato, differt. Planta minus intricato ramosa, foliis tenuioribus”) and the geographical provenance (“Hab. in rupestribus calcareis orae valentinae, Hifac; Barranc de Mascarat, pr. Calp; Cap de S. Antoni; etc. circa Dianium”).

We traced three herbarium sheets at BC (barcodes BC-82578!, BC-82520! and BC-82521!) which are part of the original material used by Font Quer (1926) to describe the new variety. The BC-82578 bears five fragments of a plant and the printed label “Institutus Botanicus Barcinonensis / Flora Iberica Selecta / Cent. I / Dec. 1934 / 86. Asperula Paui Font Quer / Butll. Inst. Cat. Hist. Nat., 1920, p. 188. / var. dianensis Font Quer / l.c., 1926, p. 57. / Valentia: in rupibus calcareis, l. Barranc de Mascarat dicto, prope / Calp, ad 50 m alt. Cotypus[1]. / Leg. Font Quer, 13 maji 1923”. The BC-82521 bears three plant fragments mounted in two sheets, and the BC-82520 bears two plant fragments mounted in two sheets, these four sheets with the same printed label of BC-82578. All the specimens at BC are part of a gathering that includes the Font Quer’s original material, for which there are some duplicates in others herbaria (see just below).

One of these duplicates is deposited at MA (barcode MA 117109!, image of the specimen available at http://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen.ma117109?loggedin=true). Some fragments are beared on the sheet and they are very well developed and preserved; the same label of the BC sheets occur on the MA sheet.

A second duplicate is preserved at JE (barcode JE00008314!, image available at: http://plants.jstor.org/stable/viewer/10.5555/al.ap.specimen.je00008314) and it bears a plant well developed and preserved, and the same label of the Font Quer’s exsiccata at BC and MA.

Among the elements selected for the typification of Asperula paui var. dianensis (at BC, MA, and JE), we here designate the BC-82578 as the lectotype of the name, since it appears to be the better preserved. Moreover, it matched the traditional concept and current use of the name (e.g. Bolòs & Vigo, 1996Bolòs, O. & Vigo, J. 1996. Flora dels Països Catalans 3. Editorial Barcino, Barcelona.; De la Torre et al., 1996De la Torre, A., Alcaraz, F. & Crespo, M. B. 1996. Aproximación a la biogeografía del sector Setabense (provincia Catalano-Valenciano-Provenzal). Lazaroa 16: 141–158.; Laguna et al., 1998Laguna, E., Crespo, M. B., Mateo, G. et al. 1998. Flora endémica, rara o amenazada de la Comunidad Valenciana. Consellería de Medio Ambiente, Valencia.; Ortega-Olivencia & Devesa, 2007Ortega-Olivencia, A. & Devesa, J. A. 2007. Asperula L. In: Devesa, J. A., Gonzalo, R. & Herrero, A. (Eds.), Flora iberica 15. Real Jardín Botánico (CSIC), Madrid: 36–56.; Mateo & Crespo, 2014Mateo, G. & Crespo, M. B. 2014. Claves ilustradas para la flora valenciana (Monografías de Flora Montiberica, 6). Jolube, Jaca.). The duplicate specimens at BC, MA and JE are isolectotypes.

Asperula paui subsp. dianensis (Font Quer) Romo, Fl. Silv. Baleares: 282 (1994)

Asperula paui var. dianensis Font Quer in Butll. Inst. Catalana Hist. Nat. 26: 57 (1926) [basionym] ≡ Asperula cynanchica var. dianensis (Font Quer) O. Bolòs & Vigo in Collect. Bot. (Barcelona) 14: 100 (1983Bolòs, O. & Vigo, J. 1983. Notes sobre taxonomia i nomenclatura de les plantes, II. Collectanea Botanica 14: 89–103.); Asperula paui subsp. dianensis (Font Quer) De la Torre, Alcaraz & M. B. Crespo, Lazaroa 16: 154 (1996De la Torre, A., Alcaraz, F. & Crespo, M. B. 1996. Aproximación a la biogeografía del sector Setabense (provincia Catalano-Valenciano-Provenzal). Lazaroa 16: 141–158.), comb. superf.

Ind. loc.: “Hab. in rupestribus calcareis orae valentinae, Hifac; Barranc de Mascarat, pr. Calp; Cap de S. Antoni; etc. circa Dianium”.

Lectotype (designated here): Valentia: in rupibus calcareis, l. Barranc de Mascarat dicto, prope Calp, ad 50 m alt., Font Quer, 13 maji 1923, BC, barcode BC-82578! (Fig. 2. Isolectotypes: BC, barcodes 82520! and 82521!; JE, barcode JE00008314!; MA, barcode MA-117109!

Figure 2. Lectotype of Asperula paui var. dianensis Font Quer (BC, barcode BC-82578). © Herbarium BC, reproduced with permission.

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ACKNOWLEDGEMENTSTop

Thanks to Dr. M. Hjertson (Museum of Evolution, Botany Section Uppsala University, Herbarium UPS), Dr. N. Ibáñez and Dr. N. Nualart (Institut Botànic de Barcelona, Herbarium BC) and R. Vallariello (Herbarium Neapolitanum, NAP) for their help. Two anonymous referees and the handling editor, made constructive criticism that improved the text.

NOTESTop

[1] The term “cotype” is not defined in the International Code of Nomenclature of algae, fungi, and plants (ICN, McNeill et al. 2012McNeill, J., Barrie, F. R., Buck, W. R. et al. (Eds.) 2012. International Code of Nomenclature for algae, fungi, and plants (Melbourne Code) (Regnum Vegetabile, 154). Koeltz Scientific Books, Königstein.), and it has not an official status. A cotype [incl. clastotype (see Swingle, 1912Swingle, W. T. 1912. Clastotypes, clonotypes, and spermotypes, means for multiplying botanical name specimens. Journal of the Washington Academy of Sciences 2: 344.)] is a fragment or duplicate specimen of the type [i.e. isotype, isolectotype, isoneotype or isoepitype according to Rec. 9C.1 of the ICN].

REFERENCESTop

1. Aizpuru, I., Aseginolaza, C., Uribe-Echebarría, P. M., Urrutia, P. & Zorrakin, I. 2015. Claves ilustradas de la flora del País Vasco y territorios limítrofes (1ª ed., 4ª reimp.). Servicio Central de Publicaciones del Gobierno Vasco, Vitoria-Gasteiz.
2. Bauhin, C. 1620. Prodromus theatri botanici. Typis Pauli Iacobi, impensis Ioannis Treudelii, Francofurti ad Moenum, 160 pp. Retrieved November, 2017, from http://bibdigital.rjb.csic.es/spa/Libro.php?Libro=1441&Hojas=
3. Bauhin, C. 1623. Pinax theatri botanici. Sumptibus & typis Ludovici Regis, Basileae.
4. Bolòs, O. & Vigo, J. 1983. Notes sobre taxonomia i nomenclatura de les plantes, II. Collectanea Botanica 14: 89–103.
5. Bolòs, O. & Vigo, J. 1996. Flora dels Països Catalans 3. Editorial Barcino, Barcelona.
6. De la Torre, A., Alcaraz, F. & Crespo, M. B. 1996. Aproximación a la biogeografía del sector Setabense (provincia Catalano-Valenciano-Provenzal). Lazaroa 16: 141–158.
7. Del Guacchio, E. & Caputo, P. 2005. Taxonomic notes on Asperula neglecta Guss. and Asperula nitens Guss. (Rubiaceae), and typification of their names. Webbia 60: 569–576. https://doi.org/10.1080/00837792.2005.10670787
8. Del Guacchio, E. & Caputo, P. 2013. Taxonomic notes on Asperula sect. Cynanchica (Rubiaceae). Taxon 62: 394–400. http://doi.org/10.12705/622.9
9. Ehrendorfer, F. & Krendl, F. 1976. Asperula L. In: Tutin, T. G., Burges, N. A., Chater, A. O., Edmondson, J. R., Heywood, V. H., Moore, T. M., Valentine, D. H., Walters, S. M. & Webb, D. A. (Eds.), Flora Europaea 3. Cambridge Unversity Press, Cambridge, London, New York & Melbourne: 4–9.
10. Ehrendorfer, F., Schönbeck-Temesy, E., Puff, C. & Rechinger, W. 2005. Rubiaceae. In: Rechinger, K. H. (Ed.), Flora Iranica 176. Verlag des Naturhistorischen Museums Wien, Vienna.
11. Ehrendorfer, F., Vladimirov, V. & Barfuss, M. H. J. 2014. Paraphyly and polyphyly in the worldwide tribe Rubieae (Rubiaceae): Challenges for generic delimitation. Annals of the Missouri Botanical Garden 100: 79–88. https://doi.org/10.3417/2012088
12. Ferrer-Gallego, P. P. 2015. Typification of the Linnaean name Asperula cynanchica (Rubiaceae). Phytotaxa 195: 98–100. https://doi.org/10.11646/phytotaxa.195.1.10
13. Gargiulo, R., Del Guacchio, E. & Caputo, P. 2015. Phylogenetic reconstruction of Asperula sect. Cynanchicae (Rubiaceae) reveals a mosaic of evolutionary histories. Taxon 64: 754–769. https://doi.org/10.12705/644.7
14. Govaerts, R., Ruhsam, M., Andersson, L. et al. 2012. World checklist of Rubiaceae. The Board of Trustees of the Royal Botanic Gardens, Kew.
15. IPNI [The International Plant Names Index] 2017. Retrieved July, 2017, from http://www.ipni.org
16. Jarvis, C. E. 2007. Order out the chaos. Linnaean plant names and their types. The Linnean Society of London in association with the Natural History Museum, London.
17. Juel, H. O. 1923. Studien in Burser’s Hortus siccus. Nova Acta Regiae Societatis Scientiarum Upsaliensis, ser. 4-5, 7: 1–144.
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