Hyparrhenia E. Fourn.

Verloove, Filip, Gonçalves Silva, Juan J. & Leliaert, Frederik, 2024, Critical notes on grasses (Poaceae) of Madeira, Portugal, Phytotaxa 670 (1), pp. 1-17 : 8-9

Hyparrhenia E. Fourn. (1886: 51 & 67)

It is quite unclear which species of Hyparrhenia occur in the island of Madeira. Historical sources evidently only reported H. hirta (L.) Stapf (back then as Andropogon hirtus L.) since H. sinaica (Delile) Llauradó ex G. López was only relatively recently resurrected ( López González 1994). Recent Madeiran authors refer all records to the latter species ( Jardim & Sequeira 2008, Menezes de Sequeira et al. 2012, Muer et al. 2020) whereas Jardim & Menezes de Sequeira (2021) reported H. hirta (s.str.?) from Desertas. However, according to Scholz et al. (2021) all collections from the island of Madeira that are preserved in LPA belong to H. hirta s.str. and Dobignard & Chatelain (2010) also only mentioned H. hirta s.str. from the island of Madeira. Yet, Menezes (1914) already reported the presence of two taxa in the island of Madeira, i.e. var. genuinus and var. pubescens , probably corresponding to the species currently named as H. hirta and H. sinaica , respectively. Our recent fieldwork and a study of specimens preserved at MADM confirm the presence of both H. hirta (but see below) and H. sinaica in the island of Madeira, the latter apparently being most widespread.

H. hirta :

Specimens examined

Funchal, July 1934, M. Grabham ( MADM 5215 ) ;

Pico dos Barcelos [Funchal], May 1937, Costa ( MADM 5218 ) ;

Vereda entre o Pico do Facho (Machico) e a Ribeira do Natal (Caniçal), 27 January 2005, J. Silva ( MADM 5216 ) ; Funchal, Levada dos Piornais, 131 m, 29 July 2015, J. Silva et al. ( MADM 5217 ) .

H. sinaica :

Specimens examined

Arrudal (Porto Moniz ), May 1932, Costa ( MADM 6521 ) ;

Caniço, May 1937, Costa ( MADM 6528 ) ;

Pico da Cruz , May 1937, Costa ( MADM 6529 ) ;

S. Gonsalo [São Gonçalo, Funchal], May 1938, Costa (MADM 6527).

Câmara de Lobos, at the estuary of Ribeira dos Socorridos, roadside, 19 April 2022, F. Verloove 14389 (BR).

Although not given any taxonomic relevance by Clayton (1969), these two taxa are accepted as distinct species by all contemporary authors in the Mediterranean area (e.g. Tison & de Foucault 2014, Pignatti 2017, Rico 2021). They are usually readily separated: H. hirta has a peduncle with 2-5 mm long hairs in the distal portion and spathes that are at least hairy and/or ciliate at the margins. In H. sinaica , in contrast, the peduncle is glabrous or with a few hairs that are not more than 1 mm long and spathes are glabrous to subglabrous. The latter also is a markedly shorter plant, rarely exceeding 60 cm in height. In the island of Madeira, these two species are easily separated.

In his world monograph, Clayton (1969) distinguished some further, African species that closely resemble H. hirta . The latter was said to never have deflexed raceme bases. However, in the island of Madeira, especially in the area of Funchal, rather numerous populations are found in which the raceme bases are obviously deflexed, at least at maturity ( Figure 3 ). Such plants could be ascribed to the tropical African H. quarrei Robyns , a widespread weed that also was reported from Australia by Clayton l.c. Simon (1989), however, placed this species in synonymy of H. hirta , judging that raceme base deflection is probably not genetically fixed. Even if this were the case, the Madeira plants further differ from true H. hirta (and H. quarrei ) in the upper raceme base being distinctly flattened ( Figure 3 ). This is a characteristic feature of sect. Pogonopodia Stapf in general and of the East African weed H. dregeana (Nees) Stapf ex Stent [syn.: H. aucta (Stapf) Stapf ex Stent ] in particular. This species is naturalized in the Hawaiian islands ( Herbst & Clayton 1998). However, in H. dregeana raceme bases are short and subequal and usually bear stiff, glassy bristles, whereas in the Madeira plants, the upper raceme base is usually clearly longer than the lower (although some variation can be observed in this respect, even in a single inflorescence!) and both are covered with soft, not bristly hairs. According to Clayton l.c., H. dregeana intergrades almost imperceptibly with H. hirta (see also Gibbs Russell 1983). Such putative hybrids of H. dregeana and H. hirta have been reported from Australia (e.g. Queensland Government 2023); it is unknown whether or not the taxonomic identity of these plants could be resolved but contemporary Australian floras and databases do not mention H. dregeana or hybrids of it (e.g. AusGrass2 2023).

Additional studies, involving molecular phylogenetic methods, are required to elucidate the identity of this enigmatic taxon from the island of Madeira: do such plants belong to Hyparrhenia hirta (which then would be more variable than previously thought, especially with regard to the shape of the inflorescence) or are they complex hybrids or hybridogenic species? In any case, a preliminary molecular analysis, based on the collection F. Verloove 14638 from Funchal, already showed that the ITS sequence of this collection clearly differs from a collection identified as H. hirta from Morocco (Skendzic 5103; Skendzic et al. 2007), and instead were more closely related to sequences from Kenya, labeled as H. papillipes ( Gill et al. 2019) ( Figure 4 ). While the trnL-F spacer exhibited a higher taxon sampling, it proved to be less informative, with only eight parsimony informative sites in its alignment (in comparison, the ITS alignment contained 64 parsimony informative sites). The phylogenetic tree derived from the trnL-F spacer sequences supports the ITS analysis, revealing a clear distinction between the plant from the island of Madeira and sequences identified as H. hirta (including a specimen collected from Tenerife, F. Verloove 14843). However, unlike the ITS analysis, it does not suggest a connection with H. papillipes .

Specimens examined: PORTUGAL. Funchal, Rua da Amoreira , roadside, common, 19 Apr. 2022, F. Verloove 14638 ( BR) ; Funchal, valley of Ribeira de João Gomes at VR-1 motorway, roadside slope, common, 20 Apr. 2022, F. Verloove 14651 ( BR) ; Funchal, São Martinho, Travessa do Amparo , roadsides, grassy slopes, etc., common all over the hill, 20 Apr. 2022, F. Verloove 14660 ( BR) ; Funchal, Papagaio Verde, Levada dos Piornais, along track, irrigation canal, common, 27 Apr. 2022, F. Verloove 14699 ( BR) .

Figures

FIGURE 3. Hyparrhenia spec. in Funchal, April 2022 (Photos F. Verloove).

FIGURE 4. Maximum likelihood trees (IQ-TREE) inferred from nuclear rDNA internal transcribed spacer (ITS) region and the plastid encoded trnL-F spacer, showing the position of the Hyparrhenia specimen from Funchal (F. Verloove 14638, BR0000027058633V, ENA/ GenBank accessions). Values at branches correspond to UFBoot2 supports (1000 replicates). Scale represents estimated substitutions per site.