Systematic Botany (2000), 25(1): pp. 33±46 q Copyright 2000 by the American Society of Plant Taxonomists Cladistic and Biogeographic Analyses of the Genera Moscharia and Polyachyrus (Asteraceae, Mutisieae) LILIANA KATINAS and JORGE V. C RISCI Departamento Cientõ®co de Plantas Vasculares, Museo de La Plata, Paseo del Bosque, 1900 La Plata, Argentina Communicating Editor: Matt Lavin ABSTRACT. The genera Moscharia (two species) and Polyachyrus (seven species) form a monophyletic group within tribe Mutisieae, subtribe Nassauviinae, de®ned by the leaves with auricles at their bases, and the capitula with 1-seriate involucre. A cladistic analysis of the species of the two genera was carried out using 22 characters from life cycle, external morphology, pollen, and trichomes. Polarity of the characters was based on the outgroup comparison method. One cladogram was produced, with 37 steps, a consistency index of 0.73, and a retention index of 0.75. The cladogram de®nes six monophyletic groups: (((Polyachyrus annus, (P. carduoides, (P. cinereus, (P. fuscus, P. gayi))), P. sphaerocephalus), P. poeppigii), (Moscharia solbrigii, M. pinnati®da)). The probable ancestral geographic area for the group, determined by Bremer9s method, is North- Central Chile area (308±358 south latitude). The study suggests that the Pleistocene could be the period of evolution of the ancestor of Moscharia and Polyachyrus. The genera Moscharia Ruiz et Pav. and Polyachyrus pitula of the pseudocephalium have the same mor- Lag. are found in Chile and Peru, occupying mainly phology, i.e., they are 2-¯owered with an involucre dry habitats. Moscharia, with two species, was re- of ®ve bracts, and the main axis of the pseudoce- viewed by Crisci (1974a) and Polyachyrus, with sev- phalium is relatively long with the capitula sessile en species and two varieties, was reviewed by Ri- and spirally disposed on this axis. Moscharia (Fig. cardi and Weldt (1974). 1C±F), on the other hand, is characterized by its di- Moscharia and Polyachyrus belong to subtribe Nas- morphic and capituliform pseudocephalia: there is a sauviinae of Mutisieae, a phylogenetically basal tribe central 1±2- ¯owered capitulum with an involucre of of Asteraceae (Bremer and Jansen 1992). These gen- 4±7 bracts, that is surrounded by 2-¯owered capitula era, together with species of Nassauvia and Triptilion, with an involucre of two bracts; the main axis of the represent a morphologically distinctive group be- pseudocephalium is shortened to form a head-like cause the aggregation of their capitula into second- or capituliform structure. In both genera the pseu- ary in¯orescences or pseudocephalia (Troll 1928; docephalium has a common involucre or pseudoin- Leppik 1960; Weberling 1992), which are hypothe- volucre, which is more developed in Moscharia. Each sized to be an advanced evolutionary feature when capitulum in Moscharia and Polyachyrus consists of: compared to a regular capitulum. Stebbins (1967) a) one inner ¯ower, the ¯ower of the capitulum that has suggested that the union of few-¯owered capit- is closest to the center of the pseudocephalium; b) ula into pseudocephalia would be a more ef®cient one outer ¯ower, the ¯ower of the capitulum that is mechanism to increase the size of the functional in- farthest from the center of the pseudocephalium; c) ¯orescence than the acquisition of new ¯owers into one pale, the bract situated between the two ¯owers a reduced capitulum. There are three steps in the of the capitulum; and d) one keeled bract, the out- formation of pseudocephalia: (1) the capitula aggre- ermost involucral bract in the capitula that sur- gate closely without losing their individual identities; rounds one or all the ¯owers of the capitulum. The (2) the capitula aggregate into a functional head, the keeled bract can be convex and humped (Polyachyrus) individual capitula being still recognizable and or conduplicate and humped (Moscharia). There are without the formation of a pseudoinvolucre; and (3) three other bracts that surround the inner ¯ower in obliteration of the identity of the individual capitula the capitula of Polyachyrus. and acquisition of a pseudoinvolucre. Polyachyrus and With regard to the other genera of Nassauviinae, Moscharia would represent the second and the third Moscharia and Polyachyrus are closely related by ho- stages of this sequence, respectively (Crisci 1974a). mologies in their pseudocephalia (Crisci 1974a; Fre- Polyachyrus (Fig. 1A±B) is characterized by its mono- ire et al. 1993). Other authors (e.g., Hellwig 1985) morphic and espiciform pseudocephalia: all the ca- reject the occurrence of pseudocephalia in Moscharia 33 34 SYSTEMATIC BOTANY [Volume 25 FIG. 1. Pseudocephalia and capitula in Polyachyrus and Moscharia. A±B, Polyachyrus foliosus; A, pseudocephalium espiciform without a developed pseudoinvolucre; B, capitulum. C±D, Moscharia solbrigii; C, pseudocephalium capituli- form with a developed pseudoinvolucre; D, capitulum. E±F, M. pinnati®da; E, pseudocephalium with a developed pseu- doinvolucre; F, capitulum. (Modi®ed from Crisci 1974a). if 5 inner ¯ower; kb 5 keeled bract; of 5 outer ¯ower; pa 5 pale; ps 5 pseudoinvolucre. 2000] KATINAS & CRISCI: MOSCHARIA AND POLYACHYRUS 35 and suggest a close relationship between Moscharia Moscharia, Polyachyrus, and related genera follows and Leucheria, another member of Nassauviinae on Crisci (1974a, b) and Ricardi and Weldt (1974). the basis of head development and chromosome OUTGROUP SELECTION. The apomorphic char- number. In a cladistic analysis of Nassauviinae (Ka- acter state was identi®ed by the outgroup compar- tinas 1994), however, Leucheria is not closely related ison method (Watrous and Wheeler 1981). The phy- to the Moscharia-Polyachyrus group. According to logenetic hypothesis proposed for the subtribe Nas- Crisci (1974a) when we compare the pseudocephal- sauviinae (Crisci 1980; Freire et al. 1993) provides ium of Polyachyrus with the ¯oral head of Moscharia a basis for choosing an appropiate outgroup for cla- the real homology of the latter is easy to ascertain. distic analysis of Moscharia and Polyachyrus (Fig. 2). Each group of two ¯owers and their surrounding This hypothesis recognizes the group formed by bract in the head of Moscharia is equivalent to a pri- Cephalopappus Nees et Mart., Moscharia, Polyachyrus, mary head in the pseudocephalium of Polyachyrus, Triptilion Ruiz et Pav., and Nassauvia Lag. (including the difference being that the bracts have been re- Calopappus Meyen) supported by the reduced capit- duced from ®ve to two. The central group of one to ula. Moscharia, Polyachyrus, Triptilion, and Nassauvia two ¯owers and their surrounding bracts correspond form a monophyletic group based on the pappus to a much reduced ®rst-order head; these bracts are shorter than the corolla, chaffy pappus, and the comparable with the accesory bracts of the capitu- pollen grains with a tectum and infratectum of the lum of Polyachyrus. same thickeness. Triptilion and Nassauvia form a Finally, the geographic distribution of both gen- monophyletic group suggested by the deciduous era is of interest. Polyachyrus is distributed in the pappus, 2±6 pappus bristles, colpi membranae with Andean and coastal dry areas of Chile and PeruÂ, sexine processes, spheroidal to spheroidal-oblate from 88 to 358 south latitude in South America, and pollen, strengthened testa epidermis, and single 2- the genus Moscharia is endemic to most of the area celled cypsela hairs. The Triptilion±Nassauvia group recognized as Central Chile, from 298 to 358 south is sister to Moscharia and Polyachyrus, therefore this latitude. These areas of Chile and Peru are of bio- group has been used as the outgroup of Moscharia geographic interest because of their high endemism and Polyachyrus. The outgroup was abbreviated (Rundel et al. 1991; Morrone et al. 1997) and the OUT for the analysis. competing hypotheses that have attempted to ex- CHARACTERS. Data from 22 characters (Table 2) were derived from the life cycle, leaf morphology, plain distributions of taxa in this restricted area pseudoinvolucre morphology, capitula arrange- (e.g., Kalin Arroyo et al. 1982; Solervicens A. 1987; ment and morphology, corolla surface and mor- Rundel et al. 1991; Morrone et al. 1997). The objec- phology, pollen, cypsela vestiture, and pappus mor- tives of this paper are: (1) to present results of a phology. Multistate characters (2, 6, 13, 20, and 22) cladistic analysis of the species of Moscharia and were treated as unordered (5 non additive). Char- Polyachyrus; (2) to analyze the character evolution of acters 6, 8, 15, and 16 are inapplicable characters in leaves, involucre and ¯owers, and pappus; and (3) the outgroup (since they are related to traits absent to estimate the probable location of an ancestral in it), they were coded as ''? '' in the data matrix geographic area for Moscharia and Polyachyrus. and treated as missing data during the analysis. Character 1 was variable in the outgroup and there- MATERIALS AND METHODS fore it was treated as polymorphic during the anal- ysis and coded in the data matrix as ``a''. Table 3 Cladistic Analysis.TAXA. The species of Mos- contains the data matrix, which was analyzed with charia and Polyachyrus, considered here as terminal the Wagner maximum parsimony algorithm of taxa, form a monophyletic group that is distin- PAUP* version 4.0 (Swofford 1999) using the guished from other related genera by the leaves ``branch and bound'' option (equivalent to ie* op- with basal auricles, and capitula with 1-seriate in- tion of Hennig86; Farris 1988). The bootstrap meth- volucre (Freire et al. 1993) (Fig. 2). Data for the mor- od (Felsenstein 1985) and Bremer support (Bremer phology of the species of Moscharia and Polyachyrus 1988; Donoghue et al. 1992) were employed to eval- were taken from previous studies (Crisci 1974a; Ri- uate the reliability of the phylogenetic estimates. cardi and Weldt 1974) and from the analysis of her- One hundred replicates were performed in the barium specimens. Table 1 lists these species, their bootstrap method. The program MacClade version acronyms, geographical distribution, and speci- 3.0 (Maddison and Maddison 1992) was used for mens analyzed with vouchers.