Recovery of the type specimen ofAvena breviaristata, an endemic Algerian grass species collected only once (1882): Morphology, taxonomy and botanical history

Abstract

Avena breviaristata, collected only once (1882) in Algeria and never re-collected since, is a very mysterious grass species because unfortunately even the type specimen got lost 60-80 years ago. Morphological information on this species was thus based on a few published descriptions, which made it difficult, however, to correctly infer the genus affiliation of this morphologically odd species. Avena breviaristata became affiliated in the past with various oat-like genera (Avenula, Helictotrichon, Tricholemma). Due to the recent rediscovery of the type specimen at the P herbarium and the opportunity to study this specimen, we report here on the morphological characters of A. breviaristata, underpinned by meaningful illustrations. They are discussed in comparison with the morphology of representative species of the above-mentioned genera. Uncommon characters of the spikelets (type of disarticulation of the rachilla, lemma structure, lodicules) and to some extent of the inflorescences, leaves and leaf sheaths support the inclusion of A. breviaristata in the North African genus Tricholemma. Considering biogeography, T. breviaristatum from the arid Hauts Plateaux in Algeria is a highly xeromorphic counterpart of the mesomorphic species T. jahandiezii, which is confined to higher altitudes of the rather humid Moyen Atlas in Morocco. This underlines the status of Tricholemma as a relic endemic. Our morphological survey supports the classification of Avenula (only A. pubescens) as separate from Helictotrichon s.str. and Helictochloa. Moreover, morphological evidence does not support an origin of A. pubescens by intergeneric hybridization between the latter genera as hypothesized in some prior studies. Especially the glabrous palea, the special shape of the lodicules and the structure of the awn show no intermediacy. The complicated history of the type collection of T. breviaristatum and the role of botanical authors are given.

Phylogenetic lineages and the role of hybridization as driving force of evolution in grass supertribe Poodae

“…). An origin as intergeneric hybrid between Helictotrichon (Aveninae) and Helictochloa (Helictochloinae) as previously discussed (Soreng & Davis, ) seems unlikely, a conclusion supported also by morphological characteristics (Gabriel & al., ).…”

“…and the Koeleriinae lineage. Additionally, there are two somewhat isolated genera with hybrid background (see above: Reticulations within major lineages), namely monospecific Lagurus (type L. ovatus ) and Tricholemma (two species; type T. jahandiezii ; Röser, , ; Röser & al., ; Gabriel & al., ) (Fig. K), making a separation of Aveninae s.str.…”

Revisiting the taxonomy of Helictotrichon schmidii (Poaceae, Poeae, Aveninae) from India, with updated regional distribution and conservation status

“…The ratio of lower glume to upper glume is 0.64–0.93. It has a well developed awn, inserted above the middle of the lemma and the more or less flattened column is rather similar to the recently described genus Tzveleviochloa and same as Trisetopsis (Wölk and Röser 2017), whereas, in Helictotrichon s. s., the awn is inserted at the middle of the lemma and the column is almost cylindrical (Gabriel et al 2020).…”

“…2G–I). Further, in contrast to Trisetopsis and Tzveleviochloa , Helictotrichon s. s. ( H. sempervirens ) has lodicules narrowly triangular in shape, with margin smooth or entire (Gabriel et al 2020), whereas lodicules in Trisetopsis are narrowly to broadly ovate, apically bi–tri‐fid, and in Tzveleviochloa lodicules are ovate, asymmetrically two‐lobed (Wölk and Röser 2017). Hence, the lodicules of H. schmidii are more similar to Tzveleviochloa than to Helictotrichon s. s. and Trisetopsis .…”

Environmental regionalization and endemic plant distribution in the Maghreb

“…A list of endemic plant taxa (species and subspecies, Table S2 ) occurring in the Maghreb area (Algeria, Morocco and Tunisia) was created according to the data available in databases ( African Plant Database , 2021 ; eflora Maghreb, 2021 ; Flore du Maroc , 2021 ; GBIF , 2021 ; North Africa Trees , 2021 ; Plants of the World online, 2021 ; The Gymnosperm Database , 2021 ; The IUCN Red List of Threatened Species, 2021 ) and the literature (Quézel & Santa, 1962 ; Baum and Rajhathy ( 1976 ); Pottier-Alapetite, 1979 – 1981 ; Navarro & El Oualidi, 1997 ; Benabid & Cuzin, 1997 ; Neffati et al, 1999 ; Ben El Mostafa et al, 2001 ; Médail et al, 2001 ; Upson & Jury, 2002 ; Besnard et al, 2007 ; Dobignard & Chatelain, 2010 – 2013 ; Le Floch et al, 2010 ; El Oualidi et al, 2012 ; Salemkour et al, 2012 ; Yahi et al, 2012 ; Alonso et al, 2013 ; Hamel et al, 2013 ; Rankou et al, 2013 , 2015 ; Miara et al, 2014 , 2017 , 2018 ; Sękiewicz et al, 2015 ; El Mokni et al, 2015 ; Bouzabata et al, 2016 ; Véla et al, 2016 ; Bouchibane et al, 2017 ; Ghrabi-Gammar et al, 2017 ; Barberá et al, 2018 ; Bouchet et al, 2018 ; Bouahmed et al, 2019 ; El Mokni & Peruzzi, 2019 ; Lauterbach et al, 2019 ; Moukrim et al, 2019 ; Djelid et al, 2020 ; Gabriel et al, 2020 ; Taib et al, 2020 ). The taxonomic nomenclature was revised according to “Index synonymique de la flore d’Afrique du Nord” (Dobignard & Chatelain, 2010 –…”