Two new species of the Andean genus Xenophyllum (Senecioneae, Compositae)

Abstract Two new species of Xenophyllum are described from the Andes, X.funkianumsp. nov. from Ecuador and X.lorochaquisp. nov. from northwestern Argentina. Both species are compared with the morphologically closest taxa and useful characters for their proper identification are provided. Detailed illustrations and distribution maps are also presented, as well as pictures of living plants when available.

The species belonging to Xenophyllum are strictly Andean, distributed from northeastern Colombia to northern Argentina and Chile. They are suffruticose plants displaying involucral bracts fused at the base, capitula radiate (disciform in one species), ray florets usually white (yellow or pink in a few species), filament collar balusterform, and style branches truncate with a crown of sweeping hairs or penicillate. Two main subgroups can be differentiated according to the type of growth form. One includes the species forming dense mats or hummocks, which have rhizome-like stems with marcescent leaves along them. The other subgroup embraces those species with genuine erect stems forming clumps or even developing a shrubby habit.
Ongoing studies aiming to obtain a modern and comprehensive taxonomic revision of the genus Xenophyllum led us to describe two new species, one from Ecuador and the other from Argentina. The Ecuadorian species has a restricted distribution area nearby the Chimborazo Volcano and is known from a few gatherings. The Argentinian species thrives in the northwestern provinces and was widely confused with other members of the genus. Detailed descriptions, illustrations, distribution maps, and taxonomic discussions are provided for each species, as well as pictures of living plants when available.

Materials and methods
This contribution is the result of an intensive review of the published bibliography and the revision of herbarium specimens kept at BA, BM, BR, GH, LIL, QCA, QCNE, US, and W. Additionally, a digital herbarium specimen was obtained from SI; herbarium acronyms follow Thiers (2019+). A Standard 16WL microscope was used for the examination of the achene trichomes. Fieldwork was conducted in Ecuador. Diagnosis. Xenophyllum funkianum is well characterized by its creeping rhizome-like stems 20-35 cm long, the straight linear leaves prolonged into a sheath-like base that bears arachnoid trichomes, the dark-burgundy sessile involucres with 13-14 involucral bracts, the 12-13 white ray florets somewhat purplish beneath, and by having whitevillous achenes.
Distribution and habitat. Endemic to Ecuador (provinces of Bolívar and Chimborazo) (Fig. 3). It grows in exposed places and sandy soils of the dry superparamo, at elevations of 4100-4300 m.
Phenology. Flowering from April to July. Etymology. The epithet honors the American botanist Vicki A. Funk (1947Funk ( -2019, who greatly contributed to the understanding of the family Compositae worldwide. Discussion. Xenophyllym funkianum is morphologically close to X. rigidum (Kunth) V.A.Funk, a species distributed in central Ecuador which overlaps its distribution area. They can be easily differentiated by the leaf lamina size (5.3-7.8 × 0.8-0.9 mm in X. funkianum vs. 12.6-13.5 × 2.3-2.4 mm in X. rigidum), involucre size (9-11 × 5-7 mm in X. funkianum vs. 11.5-12.8 × 7.2-11.3 mm in X. rigidum), and number of disc florets (20-23 in X. funkianum vs. 38-41 in X. rigidum). Moreover, X. rigidum is a larger plant and the capitula are completely enclosed among the leaves. Xenophyllym funkianum also shows morphological affinities with X. humile (Kunth) V.A.Funk; indeed, previous botanists confused the new species with it. They differ in the leaf shape (straight in X. funkianum vs. usually articulate in X. humile), involucre length (9-11 mm in X. funkianum vs. 4.6-9.3 mm in X. humile), and achene indumentum (white-villous in X. funkianum vs. glabrous in X. humile). Their way of growing is also different; X. humile forms dense mats or hummocks, whereas X. funkianum is rather a creeping plant. Another similar species is X. roseum (Hieron.) V.A.Funk, a species known from the Ecuadorian provinces of Azuay and Cañar that does not overlap the distribution area with the new species. Any confusion is unlikely since X. roseum displays pink ray florets and the young leaves usually bear a quickly deciduous arista up to 0.5 mm.
The white-villous achene indumentum of X. funkianum is composed of twin filiform trichomes, with acute to subacute, asymmetrical, slightly forked apex (Fig. 2D). This type of indumentum is also found in X. rigidum and X. roseum; however, most species of the genus have glabrous achenes.
Distribution and habitat. Endemic to northwestern Argentina (provinces of Catamarca, Jujuy, Salta, and Tucumán) (Fig. 3). It grows in exposed rocky slopes and bare soils of the dry Puna ecoregion, between elevations of 3500-5000 m.
Phenology. Flowering from January to March. Etymology. The epithet lorochaqui is the vernacular name of this plant as it was stated on the labels of the collections made by the Argentinian botanist León Castillón (pupil of botanist Miguel Lillo). It means parrot's foot referring to the leaf shape. The Spanish word "loro" means "parrot" and derives from "roro", used by some Taíno peoples and presumably adopted by the Spaniards during the colonization. On the other hand, "chaqui" is a Quichuan word meaning "foot".
Discussion. Xenophyllum lorochaqui is morphologically close to X. incisum (Phil.) V.A.Funk, X. dactylophyllum (Sch.Bip.) V.A.Funk, and X. poposa (Phil.) V.A.Funk, and it partially overlaps its distribution area with X. incisum and X. poposa. The differences against X. incisum are the leaf lamina length (3.2-7.3 mm vs. 7.9-11.5 mm in X. lorochaqui), the length of the leaf apex lobes (similar vs. central lobe longer than lateral ones in X. lorochaqui), the involucre length (6.4-8.3 mm vs 10.3-10.9 mm in X. lorochaqui), the involucral bract number (ca. 8 vs. ca. 13 in X. lorochaqui), and the ray floret number (8-13 vs. 26-39 in X. lorochaqui). Xenophyllum incisum, moreover, is a species restricted to the banks of the salt lagoons and plains with a certain humidity of the desertic Puna ecoregion. With regard to X. dactylophyllum, the leaf apex shape let anyone readily discriminate from one another. In this latter species, it is ca. 9-divided (finger-like) with the primary division extending deeper than the subsequent ones, whereas in X. lorochaqui the leaf apex is 3-notched with the central lobe longer than lateral ones. Xenophyllum dactylophyllum is distributed from central Peru to central Bolivia. Some useful characters to differentiate the new species from X. poposa are the stem indumentum (arachnoid vs. glabrous in X. lorochaqui), the leaf lamina length (2.5-6.1 mm vs. 7.9-11.5 mm in X. lorochaqui), the involucral bract number (8-9 vs. ca. 13 in X. lorochaqui), and the ray floret number (8-11 vs. 26-39 in X. lorochaqui).
It is important to bring to light some considerations that previous botanists made regarding the identification of this species. The Argentinian D. Rodríguez identified it in sched. as "Werneria incisa Phil. vel aff.!" (Werneria incisa or similar [≡ X. incisum]), and annotated "f. foliis triplo longioribus" (leaves three times longer); see Rodríguez 1382. This latter remark perfectly matches one of the aforementioned characters that discriminates X. lorochaqui from X. incisum. On the other hand, L. Castillón identified his own collection as "Werneria dactylophylla Wedd. aff.", which also reveals the failure of providing an accurate identification; see Castillón 3365. Later, Cabrera (1948) and Freire and Ariza-Espinar (2014) placed the collection Rodríguez 1382 under the varietal name X. incisum var. pubescens (Rockh.) Cabrera & S.E.Freire.
On an orthographic note, it is important to state that the epithets lorochaqui and poposa respond to the respective vernacular names of these species, and therefore, they are nouns in apposition not to be declined.
Additional specimens examined (