Two new Malagasy species of genus Piper L. (Piperaceae), Piper malgassicum and Piper tsarasotrae , and their phylogenetic position

Abstract

Introduction Most recently, treatments of the pantropical genus Piper L. (Piperaceae) included more than 2000 species (Quijano-Abril et al., 2006). The phylogenetic position of Piper L. and of family Piperaceae was inserted within the complex basal group of dicots termed "paleoherbs" (Loconte and Stevenson, 1991). More recently, APG IV (Angiosperm Phylogeny Group et al., 2016) inserted Piperaceae in order Piperales, nested within Magnoliids. The distribution of Piper is pantropical and the genus develops highly variable growth forms and biomechanical organization (Isnard et al., 2012). The highest number of species can be found in the Americas, where 500 species were listed earlier (Burger, 1972; Tebbs, 1993), which then increased to at least 1100 (Jaramillo et al., 2008) and most recently up to 1804 (Ulloa Ulloa et al., 2017). The exact number of Piper species and their exact distribution is not easy to ascertain, particularly due to the high number of taxa, some of which are difficult to distinguish from one another, resulting in many synonyms (Suwanphakdee et al., 2016). Furthermore, some species are widespread, such as P. umbellatum, while others, actively cultivated, escaped by accident and may have been naturalized, such as P. auritum, P. nigrum, or P. methysticum (Smith et al., 2008). Most species show a restricted distribution area (Marquis, 2004; Quijano-Abril et al., 2006). New species were also recently described from old herbarium collections (Görts-Van Rijn and Callejas Posada, 2005). Only two endemic species are currently known for the African continent: P. guineense and P. capense. Piper guineense is a dioecious vine, relatively similar to the majority of southwestern Asian species, whereas P. capense is a shrub with bisexual flowers, hence resembling many species of the American continents (Smith et al., 2008). The knowledge of the genus in Madagascar is far from complete. Currently, P. heimii C.DC. and P. pachyphyllum Baker are indicated for the island, while P. borbonense (Miq.) C.DC. was described for the island called at that time Île Bourbon, currently La Reunion (Weil et al., 2017), belonging to the Mascarene Islands, 600 km east of Madagascar. Its presence in Madagascar is a matter of debate, even if De Candolle (1923, 1869) had assigned some samples from Madagascar and Mauritius to this species (see Appendix 1 about herbarium samples from the site http://www.caryologia.unifi.it/tjb/Appendix1. pdf). However, this species is cultivated, which makes it more difficult to assess its natural distribution.

Evidence of a Possible Double Hybrid Origin for Two Malagasy Species of Piper L. (Piperaceae)

“…The plants were collected by E. Palchetti and N. Gandolfi in two different areas of the Ambositra region in Madagascar: the first group belonging to the P. malgassicum type was collected into the tropical rainy forest of Vohiday and the second group, belonging to the P. tsarasotrae type in the semi-dry area of Tsaratsotra village. These plants were compared with the samples of P. tsarasotrae and P. malgassicum which have been used for the previous research [13]. Samples were conserved either in ethanol 96% either as herbarium sample by the ET (Tropical Herbarium of Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 4 September 2020 doi:10.20944/preprints202009.0083.v1 Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 4 September 2020 doi:10.20944/preprints202009.0083.v1…”

“…However, its presence in Madagascar was affirmed by De Candolle [11] [12]. The fact that P. borbonense is cultivated makes more complex to understand its real distribution areal [13].…”

“…Piper malgassicum Papini, Palchetti, Gori, Rota Nodari and Piper tsarasotrae Papini, Palchetti, Gori, Rota Nodari, were recently described as new Malagasy species [13] and are of economic interest, since their dried fruits are often mixed with P. borbonense to produce the typical Malagasy spice called in local language "voatsiperifery" pepper.…”

Histochemical observations in Piper malgassicum (Piperaceae) with a special focus on the epidermis

“…The genus Piper L. belongs to the family Piperaceae and includes more than 2000 species with a pantropical distribution (Quijano-Abril et al 2006), most of them from America (Ulloa Ulloa et al 2017). Nowadays, the phylogenetic position of Piper as well as of the Piperaceae family, is among the so-called "paleoherbs", a phylogenetically complex basal group of dicots (Loconte and Stevenson 1991;Chase et al 2016), within the order Piperales (Jaramillo et al 2008;Palchetti et al 2018). Piperales are herbaceous or woody plants exhibiting quite primitive morpho-anatomical features (Isnard et al 2012) Piper species can be described either as shrubs, or more frequently, as creepers and lianas in the equatorial regions (Jaramillo et al 2001).…”

Diagnoses and descriptions in Plant Taxonomy: Are we making proper use of them?

“…Despite the explicit and satisfactory differentiation in the ICN , we argue that the distinction of a diagnosis and a description is not clear to many taxonomists these days, especially the younger ones. New taxa, especially new species, are often described supported only by descriptions, without a diagnosis (e.g., Berry & Galdames, ; Van der Maesen, ; Palchetti & al., ; Shui & al., ; Vaezi & al., ; Vladimirov & al., ), or other times diagnostic and descriptive information is joined under one or the other (e.g., Kuijt & Delprete, ). In some cases, a diagnosis is presented after a description (e.g., Arigela & al., ; Guzmán‐Guzmán, ; Xiao & al., ), which we consider that further adds to the current state of confusion.…”