The typification of the names Brachypodium ×cugnacii and B. ×paui (Brachypodieae, Poaceae) is discussed. All relevant sources, as well as specimens, illustrations, and references cited in the protologues are carefully examined for the purpose to fix the application of the names. The two names above mentioned are lectotypified using specimens preserved at P and BC herbaria, respectively. Finally, a comment on the nomenclatural type of Brachypodium retusum is reported.
RESUMEN
Se discute la tipificación de los nombres Brachypodium ×cugnacii y B. ×paui (Brachypodieae, Poaceae). Todas las fuentes de información, como son los especímenes de herbario, ilustraciones y referencias relevantes citadas en los protólogos, se han evaluado cuidadosamente con el fin de fijar la aplicación precisa de los nombres. Los nombres mencionados se han lectotipificado utilizando especímenes conservados en los herbarios P y BC, respectivamente. Finalmente, se aporta un comentario sobre el tipo nomenclatural de Brachypodium retusum.
Brachypodium Palisot de Beauvois (1812: 100, 155) (Brachypodieae, Pooideae) is a genus of temperate grasses distributed worldwide (Smith, 1980; Schippmann, 1991; Catalán & Olmstead, 2000; Piep, 2007) and comprises 15–20 species (Schippmann, 1991; Catalán et al. 1995, 2012; 2015; Díaz-Pérez et al., 2018; POWO, 2023). The genus Brachypodium represents a model system that is advancing our knowledge of the biology of grasses in the postgenomics era (Draper et al., 2001; IBI, 2010).
For the Iberian Peninsula, the most recent treatment of this genus has been generated by López González (2021). This author recognized only a species in the Brachypodiumdistachyon (L.) P. Beauv. complex. However, Catalán et al. (2012, 2016) and López-Álvarez et al. (2012, 2015, 2017) published a comprehensive treatment of this complex and recognized three species on the basis of morphological and genetic characters and geographic distribution: B. distachyon, B. hybridum Catalán, Joch. Müll, Hasterok & G. Jenkins, and B. stacei Catalán, Joch. Müll, L. A. J. Mur & T. Langdon.
Interspecific natural hybridization in Brachypodium via pollen flow was highlighted by Khan & Stace (1999). Brachypodium ×paui Sennen was described as a hybrid between B.retusum (Pers.) P. Beauv. and B. distachyon (see Sennen, 1911).
Brachypodiumretusum is a rhizomatous perennial C3 grass that grows in dry grasslands, shrublands and open woodlands of the Mediterranean Basin, Arabian Peninsula, and Africa (Morocco, Algeria, Tunisia, and Egypt) (Smith, 1980; Schippmann, 1991; Cope et al., 2007; López González, 2021; AFA, 2023; POWO, 2023). This species is a rhizomatous plant, with stems 15–50 cm, erect or geniculately ascending, slender, glabrous, leaves up to 10 cm, often less, acute, the cauline patent, distichous; raceme 4–9 cm, dense, stiffly erect, with 1–5(–9) spikelets; spikelets (12–)20–30 mm, linear, overlapping considerably, glabrous, glaucous, with (6–)10–15 florets, glumes acute; lemma 7–8 mm, ovate-lanceolate, abruptly narrowed to the apex; awn 2–4 mm, straight, sometimes absent on lower lemmas (Smith, 1980; Schippmann, 1991; López González, 2021).
Brachypodium distachyon is a grass species native to southern Europe, northern Africa and southwestern Asia east to India (Schippmann, 1991; POWO, 2023). The close relationship of B. distachyon with economically important temperate cereals and forage grasses combined with many other favorable attributes, such as its very small nuclear genome, simple growth requirements, small size, and annual life cycle, prompted Draper et al. (2001) to propose it as a model organism (see IBI, 2010). The name of B. distachyon is restricted to a stiffly erect annual plant up to (2–)6–15(–56) cm high, culm with (1–)3–4 nodes, leaves (1–)3–7(–8.5) cm × (0.25–) 1.5–2(–4) mm, short, bright green and (1–)2(–4) spikelets per panicle, spikelets (9.2–)14–15(–24) mm, and lemmas (5.2–)7–8(–11) mm, 7-veined, awned, with awn (5–)10–11(–15.2) mm. Brachypodium hybridum is an erect or spreading annual plant up to (3.5–)30–40(–78) cm high, culm with 3–7(–18) nodes, leaves 7–8(–16) cm × (0.7–)2–3(–4.3) mm, long, pale dark green and 3(–6) spikelets per panicle. Finally, B. stacei is an erect annual grass up to 44–76(–150) cm high, with (1–)4(–9) nodes, soft leaves, curled, patent, pale green, (1.6–) 7–8(–15.1) cm × (0.26–)2–3(–7) mm, and (1–)3–4(–5) spikelets per panicle (see Catalán et al., 2012, 2015, 2016). From the material studied by Catalán et al. (2012, 2016) and from the study of some herbarium sheets collected by Sennen from Llers (Girona, Spain) (see e.g., P03218688, P06768158) the parent of B. ×paui could very probably be B. hybridum.
On the other hand, Brachypodium ×cugnacii A. Camus was described as a hybrid between B. pinnatum (L.) P. Beauv. and B. sylvaticum (Huds.) P. Beauv. (see Camus, 1931). Brachypodium sylvaticum reportedly produces natural hybrids with B. pinnatum in Europe (Long, 1989), and synthetic hybrids with B. pinnatum and B. phoenicoides (L.) Roem. & Schult. are viable (Khan & Stace, 1999).
Brachypodium sylvaticum is a species common in Europe, but also extends into Asia and North Africa (Catalán & Olmstead, 2000; Catalán et al., 2015; Díaz-Pérez et al., 2018). This species is shortly (or scarcely) rhizomatous, usually pendent at tip of raceme, leaves usually 6–10 mm wide, sheaths usually pubescent, sometimes glabrous, raceme with (3–)5–12 spikelets, lemmas 6–12 mm, with awn 7–15 mm.
Brachypodiumpinnatum is a widespread species in temperate regions of the Northern Hemisphere, it is a thermophilous species but also grows in cool continental climates and reaches higher latitudinal limits in East-Central Asia than B. sylvaticum, which grows in areas with more oceanic climates (Tzvelev, 1976; Catalán et al., 2016). Brachypodiumpinnatum typically grows in more open areas, such as calcareous grasslands. It is extensively rhizomatous, usually erect, leaves 3–6 mm wide, raceme with (3–)6–15 spikelets, lemmas 6–11 mm, often glabrous, with awn 1–5 mm (Tzvelev, 1976; López González, 2021). It is morphologically similar to B. rupestre (Host) Roem. & Schult. which also apparently has the same cytotypes as its close congener (2n = 2x = 18; 2n = 4x = 28) (see Stace, 2019) and could also have been involved in the hybridization with B. sylvaticum.
The present paper is a further step of our contributions to Brachypodium nomenclature (see, e.g., Fabado & Ferrer-Gallego, 2021; Ferrer-Gallego & Martínez Labarga, 2022a, b), the purpose of this paper is to contribute to the stability of the nomenclature of B. ×paui and B. ×cugnacii through the lectotypification of each of these two names.
MATERIAL AND METHODS
This work is based on the analysis of protologues, examination of relevant literature and study of the specimens conserved in the herbaria B, BC, BCN, DR, FR, MA, MPU, P, US, and VAL (acronyms follow Thiers, 2023). The identity of the designated types has been verified with the current use of their respective names. The typified names are arranged in alphabetic order, followed by their homotypic synonyms (indicated with the symbol “≡”). The names in current use are indicated in bold italics typeface.
RESULTS AND DISCUSSION
<italic>Brachypodium</italic> ×<italic>cugnacii</italic>
The protologue of Brachypodium ×cugnacii (Camus, 1931) includes the name “× Brachypodium Cugnacii A. Camus” and the hybrid formula “B. pinnatum P.B. × [Brachypodium] silvaticum R. et S. var. villosum Lej. et Court.”, and a complete diagnosis followed by the geographical provenance and gathering “Seìne-et-Oìse: Verrières (A. de Cugnac, 1930)”. This citation represents a syntype according to the Art. 9.6 of Shenzhen Code (hereafter as “ICN”; Turland et al., 2018). The protologue also includes a diagnosis and a table with several features to distinguish this hybrid and their parents.
Saint-Yves (1934: 435) synonymized the name Brachypodium ×cugnacii with B. pinnatum var. glaucovirens (this taxon is currently recognized as an independent species by several authors, see e.g., Catalán et al., 2015; POWO, 2023). Schippmann (1991) treated B. ×cugnacii as a synonym of B. sylvaticum subsp. sylvaticum, and reported “typum non vidi”.
We have found two specimens at P (P03471271 and P03628878) for Brachypodium ×cugnacii. P03471271 is part of the original material, bearing a plant, with leaves and spikelets, and an original label handwritten by A. Camus annotated as “Herbier E. G. Camus & A. Camus / × Brachypodium Cugnacii A. Camus / B. pinnatum × silvaticum inter parentes / Seìne-et-Oìse: Verrières / 1930 / Legit de Cugnac / A. Camus” (Fig. 1). P03628878 bears a complete specimen, with leaves and flowers, and a handwritten label annotated as “× Brachypodium Cugnacii // S-et-O: Verrières / 7-VII-1931 / R. de Cugnac”. Since the year of collection (1931) is not that reported in the protologue, P03628878 cannot be considered as part of the original material for B. ×cugnacii. As a consequence, P03471271 is here designated as the lectotype for the name B. ×cugnacii. This specimen and the rest of the material match the traditional concept and current use of the name (Camus, 1931; López González, 2021).
Brachypodium ×cugnacii A. Camus, Bull. Soc. Bot. France 78: 100. 1931 [= B. pinnatum (or cf. B. rupestre) × B. sylvaticum]
Lectotype of <italic>Brachypodium </italic>×<italic>cugnacii</italic> Camus (P03471271). Image courtesy of the herbarium P, reproduced with permission.
Sennen’s protologue (1911: 133) of Brachypodium ×paui (a taxon numbered with “409”) includes the hybrid formula “(B. ramosum × distachyon)?” followed by a complete diagnosis and the geographical provenances “Hab.: Garrigues et olivettes à Llers, Pont-de-Molins, Figueras; pentes du Tibidabo, près Barcelone; Benicarló à Bóbola!”.
Schippmann (1991) reported: “syntypi: “Plantes d’Espagne no. 409, Brachypodium Paui Sen.,? (B. ramosum + distachyon) Sen., Catalogne: Llers et Pont de Molins, olivettes, Juin 1907” (B!, FR!, LD!, M!); “Plantes d’Espagne no. 1046, Brachypodium Paui Sen., (B. ramosum + distachyos)? Sen., Catalogne: Barcelone, pentes du Tibidabo, VI.1910” (B!, FR!, LD!); specimen scheda manu scripta instructa: “Catalogne, Llers, olivettes, 19.VI.1905, F. Sennen” (B!); specimen scheda manu scripta instructa: “Catalonia, Figueras, champs, VI.[19]10, leg. Sennen” (LD!)”, and also commented about the material type and plant that “Das Typusmaterial ist in vielen Doubletten vorhanden. Einige der anatomisch und morphologisch untersuchten Pflanzen zeigen zwischen B. distachyon und B. retusum intermediäre Merkmale, bei anderen handelt es sich eindeutig um B. retusum” [The type material is available in many duplicates. Some of the anatomically and morphologically examined plants show intermediate characters between B. distachyon and B. retusum, others are clearly B. retusum] and “Sennen weist auf den Hybridcharakter dieses Taxons hin” [Sennen points out the hybrid character of this taxon]. Therefore, not all the specimens are syntypes.
We traced several original specimens of Brachypodium ×paui at B, BC, BCN, DR, FR, MA, MPU, P, US, and VAL herbaria. Among them, several (BC616312, BC616227, BC118838, BC71120, BC-Sennen [without number], BCN78982, DR061516, FR0031230, P02569267, P03139060, P03218686, P03218691, MA14348, MA14350, MA163576, MPU027893, MPU027892, VAL172458) are number with “409” as reported in the protologue, and collected in “Catalogne: Llers et Pont de Molins” in June 1907. These specimens can be considered as syntypes (Art. 9.6 of ICN) and therefore have a preference for lectotype designation according to Art. 9.12 of ICN. We designate as the lectotype of the name B. ×paui the specimen BC616227 (Fig. 2) since it bears a well-developed and complete plant which matches the traditional and current use and concept of the name B. ×paui (Sennen, 1911; López González, 2021): plants extensively branched, erect or geniculately ascending stems, glabrous; leaves up to 10 cm × 2–4 mm, with prominent spaced veins, flat, tough, becoming convolute when dry, acute, the cauline patent, distichous; ligule ca. 1 mm; raceme 4–9 cm, dense, stiffly erect, with 1–5(–7) spikelets; spikelets (12–)20–30 mm, linear, glabrous, glaucous, with (6–)10–15 florets; glumes acute, the lower 4–5 mm, the upper 6–7 mm; lemma 7–8 mm, ovate-lanceolate, abruptly narrowed to the apex.
Brachypodium ×pauiSennen, Bull. Géogr. Bot. 21(259): 133. 1911 [= B. distachyon complex (probably B. hybridum) × B. retusum]
Lectotype (designated here): [Spain] Catalogne,Llers et Pont de Molins, June 1907, F. Sennen 409 (BC616227 [photo!]; Fig. 2). Isolectotypes:BC616312, BC118838, BC71120, BC-Sennen [without number], BCN 78982, DR061516, FR0031230, MA14348, MA14350, MA163576, P02569267, P03139060, P03218686, P03218691, MPU027893, MPU027892, VAL172458.
Lectotype of <italic>Brachypodium </italic>×<italic>paui</italic> Sennen (BC616227). Image courtesy of the herbarium BC, reproduced with permission.
Note on the nomenclatural type of <italic>Brachypodium retusum</italic>
The specimen now barcoded as L0043873 is the “holotype” of Bromus retusus Pers. according to Schippmann (1991: 106), who stated: “holotypus: “Bromus retusus Syn. plant. Enc. Botan., [...] Gallia Meridian.” (L!). - Die Herbarien BM, E, G, GOET, LD, LG und NY haben auf Anfrage mitgeteilt, daß sie kein Typus-Material dieser Art besitzen.” [Herbaria BM, E, G, GOET, LD, LG and NY have indicated upon request that they do not have any material of this type]. Thus, Schippmann unintentionally or “inadvertently” lectotypified the name. Moreover, we have also not found any further herbarium sheet with Persoon’s original material of B. retusus and, probably, the specimen at L is the only original material used by the author for the description of this plant. However, as we cannot exclude that there would be more than one specimen of this taxon in his collection, we consider the specimen L0043873 as the lectotype (corrected here according to Art. 9.10 of the ICN) of the name B. retusus, admitting that the specimen might well be the holotype.
Lectotype (designated by Schippmann in Boissiera 45: 106. 1991, corrected here according to Art. 9.10 of the ICN): [France] in Gall. meridion, s.d., Persoon s.n., (L0043873; image available at https://bioportal.naturalis.nl/multimedia/L++0043873_0339368672/term=Brachypodium+retusum&from=38).
ACKNOWLEDGEMENTS
Thanks to Dr. Ginés López González and Dra. Pilar Catalán for their advice, assistance, and valuable comments that improved this work. Thanks to Neus Ibáñez (Institut Botànic de Barcelona) for his help in the study of the specimens in the herbarium BC.
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