Ampelodesmos, Link, 1827

Vázquez, Francisco Maria, Márquez, Francisco, García, David & Oualidi, Jalal El, 2025, A taxonomic revision of Stipeae s. l. tribe (Poaceae) in N Africa, Phytotaxa 699 (1), pp. 1-174 : 126-128

Ampelodesmos discussion

There are no previous studies of this kind at the level of the lemma surface. The SEM micromorphology of the lemma surface of Ampleodesmus mauritanicus was studied and contrasted with the other N African Stipeae species studied. Proximity between Ampelodesmus and some of the Stipeae taxa studied was noted.

The morphology of the long cells is similar to that observed in members of the genus Macrochloa , with thick, sinuous walls up to 7 µm thick. The silica and cork cells are distributed in a regular manner, interspersed with long cells of similar appearance and dimensions to the short cells of the genus Celtica . However, the hooks and prickles in Ampelodesmus have a morphology, distribution and density that is partly reminiscent of some representatives of the genus Stipa such as those of the Stipa sect. Leiostipa .

No singularities in elements exclusive to Ampelodesmos were detected at the surface of the lemma. The combination of characters in Ampelodesmos is similar to those of the other three genera studied for N Africa. The micromorphological study of the surface of the lemma shows this combination of distinctive characters in the case of Ampelodesmos mauritanicus .

Overall discussion

The study of the micromorphology (SEM) of the lemma surface in Stipeae of N Africa has provided additional information that in many cases, supports the separation of taxa at the genus, section, specific or infraspecific level.

Of all the characters studied, long cells, hooks, prickles and silica cells were the elements that have provided the most information in terms of diversity of morphology, distribution and possible grouping with other elements studied. Characters such as stomata, cork cells, and macro-hairs have often been complementary on numerous occasions, supporting variations observed in other more diverse characters.

The presence of long, smooth-walled cells less than 2 µm thick facilitates the separation of several groups of taxa, including some with long cells less than 3 times as long as they are wide, and others in which the long cells are more than 4 times as long as they are wide. Taken together, groups with long cells> 4 times as long as they are wide do not have hooks or prickles on the surface of the lemma (occasionally in Oloptum ), as in Piptatherum and Celtica , whereas groups with long cells <3 times as long as they are wide, which usually have prickles on the surface of the lemma, as in Stipellula or Achnatherum .

Thick-walled long cells, sinuous or wavy, usually occur in the Macrochloa and Celtica groups, and occasionally in Stipellula nitens , except in the latter where the surface of the lemma also has hooks and prickles, mainly at the apex, and clusters of at least three elements are continuously interspersed between the long cells: hook+ silica cell+ suberosal cell. The latter formation is reduced to silico-suberous pairs in the long cells of smooth-walled taxa.

Of all the elements and taxa studied, it is worth noting the singularities found, such as the unpointed hooks of Stipa almeriensis , the angulated prickles typical of Stipellula parviflora or the presence of stomata at the apex of the lemma of some of the members of the genus Macrochloa . All these singularities have been observed in some Stipeae from other latitudes, such as in the species of Stipa sect. Stipa from Central Asia ( Nobis et al., 2014), where some representatives of the genus Austrostipa ( Bustam, 2010) show the presence of angulated prickles on the surface of the lemma. The presence of stomata along the column has not been documented in Stipeae , although it has been documented in the subfamily Pooideae in some representatives of the genus Briza L. ( Thomasson, 1986)

Numerical Taxonomy

It is necessary to make a general caveat about the contrast of these results with previous work. The results of this study would not be comparable with previous studies in which we have worked with information from molecular studies (Wiens, 2000).

The results found show the presence of homogeneous groups that repeatedly appear clearly separated from the rest, as the genus Ampelodesmos , a genus outside the Stipeae , but of hybrid origin in which a representative of the Stipeae participated, brings it closer in the results of several analyses to the genera Stipa , Celtica and Macrochloa . These results are not comparable with studies based on molecular data (Romaschesko et al., 2014) in which the similarity of Ampelodesmos to taxa of the groups Oryzopsis Michx. (p.p.), Psammochloa Hitchc. , Achnatherum , Trikeraia Bor or Ptilagrostis Griseb. was demostrated, with the exception of Stipa zalesskii Wilensky ex P.A. Smirn. In previous studies of a greater number of representatives of the Stipeae , such as Romaschesko et al., 2012, or more recently Gallagheret et al., 2022, Ampelodesmos was in the same clade as Stipa , together with other previously indicated taxa ( Oryzopsis , Psammochloa Hitchc. , Achnatherum , Trikeraia Bor and Ptilagrostis Griseb. ). Our results are close to those of the two studies mentioned above.

Our results show the distance between the Macrochloa group and the rest of the taxa, even in the analysis of macromorphological characters which seemed to support a shared clade with Celtica , although with a distance between the two groups of 0.25. These results are similar to those obtained by Hamasha et al., 2012; Romaschesko et al., 2012, Tkach et al., 2021 and Gallagheret et al., 2022.

The clade that uniformly distinguishes the representatives of the genus Stipa gives us additional information about the diversity of the species it contains. The analysis allows us to distinguish the differences of the Macrochloa group from the section Stipa and, in a less defined way, the groups of serie Africanae and Section Leiostipa can be identified. However, the taxa of the Barbatae series, often appear integrated with those of the section Leiostipa . Similar results were obtained by Nobis et al., 2020, when studying the groups of the genus Stipa of Central Asia, where it was no possible to separate the species of the section Leiostipa and serie Barbata with a clear distance, while the representatives of the section Stipa appear clearly differentiated from the rest. These results allow us to justify more solidly the already established Sections Stipa and Leiostipa , as well as the new serie Africanae , while the series Barbatae will remain in section Leiostipa .

The clades that separate the taxa Achnatherum , Piptatherum , Oloptum , and Stipellula are those that have provided a greater diversity of results depending on the type of analysis performed. These results are similar those in the recent literature, supported by molecular studies (Romaschesko et al., 2012, Tkach et al., 2021 and Gallagheret et al., 2022).

In general, the Achnatherum group was distant from the other genera in all analyses: Oloptum , Piptatherum and Stipellula . In addition, the results for Stipellula were similar to those for Achnatherum , indicating a group that is easily separated, appearing distinctive after analysis of macromorphological characters, as well as in the case of Achnatherum , after micromorphological analysis.

Piptatherum and Oloptum share many morphological characters, which contrasts with the results from studies such as those by Hamasha et al., 2012; Romaschesko et al., 2012; Tkach et al., 2021 and Gallagheret et al., 2022. These contrasts indicate that the results obtained are limited, and should be treated with caution when compared with analyses supported by molecular studies.

The most disparate results found are those related to the genus Stipellula , since the species of this genus show great diversity after aggregation and similarity study. Usually, Stipellula magrebensis and Stipellula capensis appear close to the two previous species and Stipellula nitens somewhat distant, but in the same clade. However, Stipellula parviflora appeared outside the clade the genus Stipellula in all analyses and was generally closer to Achnatherum , Oloptum and Piptatherum .

These results were partly reflected in studies with previous molecular data by Hamasha et al., 2012; Romaschesko et al., 2012, partly in Krawczyk et al., 2022 and Romaschesko et al., 2014.

Stipellula parviflora appears in all analyses separate from the newly defined group of the genus Stipellula . In all cases, it appears to be integrated into the taxa clades of Achnatherum , Oloptum and Piptatherum , as previously indicated by Nobis et al., 2020 (sub Achnatherum parviflorum (Desf.) Nobis ). However, its position is not clearly defined, and the study carried out is partial. Further studies are needed, including new taxa from other latitudes (e.g. S. tibestica , S. tigrensis ), and new molecular characters are integrated, as well as possible taxa close to Stipellula parviflora . This would provide a more complete overview of the taxon and the group to which it belongs. With this in mind, Stipellula parviflora has been retained in the group in which it is currently accepted.

Aknowledgments

The work presented is the result of a collaboration between the Centro de Investigaciones Científicas y Tecnológicas de Extremadura (CICYTEX, Spain) and the Emirates Center for Wildlife Propagation (ECWP). Some of the funds, data and samples used in this study were provided by the International Fund for Houbara Conservation (IFHC). We are grateful to His Highness Sheikh Mohamed bin Zayed Al Nahyan, President of the United Arab Emirates and founder of the IFHC, His Highness Sheikh Theyab bin Mohamed Al Nahyan, Chairman of the IFHC, and His Excellency Mohammed Ahmed Al Bowardi, Deputy Chairman, for their support. The study by the Emirates Center for Wildlife Propagation in Morocco was conducted under the guidance of Reneco International Wildlife Consultants LLC, a consulting company that manages the IFHC’s conservation programmes. We would like to thank Dr Frédéric Lacroix, Managing Director of Reneco, for his supervision and all Reneco staff who participated in the data collection. We would like to thank Dr Frédéric Lacroix, Managing Director of Reneco, for his supervision and all Reneco staff who participated in the data collection. Also, Jean-François Léger for their collaboration in the Moroccan recollections; special gratefulness to Mathieu Chambouleyron for their initial proposal: study the Moroccan stipoids; her constant help in the recollections, assistance in the visit of herbaria and review of the ecology and habitat of species. We would also like to express our gratitude to Cecile Aupic, P herbarium; Caroline Loup, MPU herbarium; Alain Doubignard, H-DOB herbarium; Fred W. Stauffer, Joel Calvo and Nicolas Fumeaux, G herbarium, Leopoldo Medina, MA herbarium, and finally to Bauer Norbert in the BP herbarium and the Natural History Museum of Budapest. We are grateful for their help and patience, and for the facilities provided during the study of the material preserved in these collections. To Dalil Amari (Algerian voucher localities), Abbès Tanji (collections in Western Morocco), Alicia Gil, Laura Nogales and Pedro Del Viejo, for help with the material processed in the HSS herbarium. Finally, thanks to Fergus Crystal for an English revision of the manuscript, together two anonymous reviews and Marcis Nobis than contributed to improve the quality of the work.