Senecio repangae(Asteraceae): A new endemic species from the north‐eastern North Island, New Zealand

Abstract

A new species Senecio repangae is described from the north-eastern North Island, New Zealand, where it grows primarily on offshore islands. It has previously been included within the widespread New Zealand endemic Senecio lautus, from which it is distinguished by its much taller, sparingly branched habit, longer and narrower capitula, much shorter, widely and unevenly spaced, recurved, incised ray florets, and by its chromosome number (2n = 100). A new subspecies, S. repangae subsp. pokohinuensis, endemic to the remote Mokohinau Islands group is also recognised. This allopatric taxon is distinguished from S. repangae subsp. repangae by its sparsely hairy, glabrescent, glaucous, adaxial leaf surface, smaller involucral bracts, and evenly spaced, longer, ray florets which are never recurved. The distribution, ecology, cytology, reproductive biology, conservation, and relationships of both subspecies to other New Zealand Senecio species are assessed.

The delimitation and evolutionary history of the Australasian Lautusoid group of Senecio (Asteraceae: Senecioneae)

“…Taxon sampling. -Using taxonomic and phylogenetic treatments that include S. lautus or formulate hypotheses about the identity of its closest relatives (Ornduff, 1960;Sykes, 1971;Lawrence, 1980Lawrence, , 1985aWebb & al., 1988;Belcher, 1992a, b;de Lange & Murray, 1998;Thompson, 2005aThompson, , b, 2006de Lange & al., 2014), a total of 23 Australasian Senecio species were identified as putative Lautusoid species (Table 1). A total of 18 of these were included in our molecular phylogenetic study (Table 1).…”

“…Although incomplete lineage sorting could be an alternative explanation for some of the incongruence between nuclear and plastid phylogenies, evidence supporting a significant role of hybridization in the evolutionary history of Senecio and other Senecioneae genera is accumulating (e.g., Abbott & Lowe, 2004;James & Abbott, 2005;Abbott & al., 2009;Pelser & al., 2010aPelser & al., , 2012Calvo & al., 2013). Aside from patterns of phylogenetic incongruence that can be explained by hybridization, putative hybrids have been identified in karyological studies (e.g., Beuzenberg, 1975;Lawrence, 1980;de Lange & Murray, 1998), through the identification of chimeric DNA sequences (Pelser & al., 2012), patterns of DNA sequence polymorphism (e.g., Mas de Xaxars & al., 2015), additive AFLP profiles (Kirk & al., 2004), and by observing plants that are morphologically intermediate between putative parental species (e.g., Belcher, 1956;Calvo & al., 2015).…”

“…Most species for which chromosome numbers are known are 2n = 40, but higher chromosome numbers (2n = 80, 100) are also reported (e.g., Beuzenberg, 1975;Lawrence, 1980Lawrence, , 1985a 1998Ahrens & James, 2015). These higher chromosome numbers indicate that these species are of polyploid origin (Lawrence, 1980;de Lange & Murray, 1998). It is, however, mostly unknown if the 2n = 80 and 2n = 100 Lautusoid species are of autopolyploid or allopolyploid origin and, if the latter, what their parental species are.…”

The vascular flora of Aorangi Island, Poor Knights Islands, northern New Zealand

“…comm. ), including an extant population of the snail Placostylus hongi, as well as having at least two endemic vascular plants (a Hebe and a Senecio (de Lange et al 1995a;de Lange & Murray 1998)). Indeed, the only significant difference between these island groups is that the Mokohinau Islands have been heavily modified to the present time by humans and kiore (Rattus exulans) (Cameron 1990;de Lange et al 1995a), while the human influence on the Poor Knights ceased by the 1820s.…”

Taxonomic notes on the New Zealand flora: new names in Piper (Piperaceae)

“…peltatum f. peltatum (Gardner 1997), and it is amply distinguished from that subspecies by its more consistently peltate, thicker, dull green leaves, and possibly, its chemistry (Gardner 1997), as well as its more highly ornamented seeds (Eagle 2006), it is here elevated to subspecies rank. This is the preferred rank used by the majority of New Zealand botanists for minor allopatric segregates (Edgar 1986;Sykes 1992;Heenan 1998;de Lange & Murray 1998;de Lange & Cameron 1999;de Lange & Heenan 2001;de Lange 2010), and so is more appropriate than forma which is a rank reserved for minor genetically fixed variants that occur sympatrically within the parent gene pool (see Garnock-Jones & Molloy 1982;Heenan 1998;de Lange & Cameron 1999;Stace 1991;Stuessy 1990 47, 22 (1915) Macropiper excelsum f. psittacorum (Endl.) A.C.Sm., Bot.…”