Xenophyllum rosenii (R.E.Fr.) V.A.Funk, Novon 7(3): 240. 1997.

Calvo, Joel & Moreira-Munoz, Andres, 2020, Taxonomic revision of the Andean genus Xenophyllum (Compositae, Senecioneae), PhytoKeys 158, pp. 1-106 : 1

15. Xenophyllum rosenii (R.E.Fr.) V.A.Funk, Novon 7(3): 240. 1997.

Werneria rosenii R.E.Fr., Nova Acta Regiae Soc. Sci. Upsal., ser. 4, 1(1): 90. 1905 [ “Rosenii”]. Type. Argentina. Jujuy: nevado de Chañi, 5200 m, 29 Nov 1901, R.E. Fries 862 (lectotype: Fries’ collection at UPS as the first-step lectotype, designated as “holotype” by Funk (1997a: 240); UPS-V-833144 (digital image!) as the second-step lectotype, designated here; isolectotypes: CORD-00005639 (digital image!), P-02088549 (digital image!), S-R-6527 (digital image!), UPS-V-833133 (digital image!), US-00037307!).

Description.

Suffruticose plant, forming clumps of erect stems. Rhizomes 6-10 × 0.4-0.5 cm, horizontal to oblique, glabrous. Stems 4-8 cm tall, simple or branched, glabrous, usually with leaves restricted to the upper part. Leaves imbricate, extending into a glabrous sheath-like base; leaf laminas 7-11 × 3-4.5 mm, linear-spatulate (broadened upwards), 2-forked at the apex (incision depth ca. 1/3 of the total length), entire, flat to elliptic or almost terete upwards in cross section, glabrous, 1-nerved above (barely visible), 1-nerved beneath, fleshy, matte; leaf lobes 2.3-4.5 × 1-1.5 mm, acute to obtuse. Capitula radiate, erect, sessile. Involucres 11-13.2 × 8-10 mm, cupuliform; involucral bracts 11 to 12, 5.6-7.2 × 1.9-3.2 mm, rather acute at the apex, greenish, purple-edged. Ray florets ca. 18; corollas ca. 9.2 × 1.7 mm, 3 to 4-veined, subentire to 3-toothed at the apex, conspicuously surpassing the involucre, white. Disc florets ca. 50; corollas 5-5.1 mm long, yellowish; style branches penicillate, purplish. Achenes ca. 3.5 × 0.9 mm, cylindrical, 6 to 8-ribbed, glabrous; pappus 8-10 mm long, barbellate, whitish. Chromosome number unknown.

Iconography.

Cabrera (1948: 52, fig. 2, sub Werneria rosenii ).

Distribution and habitat.

Restricted to northwestern Argentina and southwestern Bolivia. Argentina (Jujuy, Salta [expected]), Bolivia ( Potosí). It grows in wet meadows and rocky places of the dry puna ecoregion, between elevations of 4600-5200 m (Fig. 20 ).

Xenophyllum rosenii is hitherto known from very few gatherings, i.e., the type locality in Jujuy (Argentina) plus two collections from southern Sur Lípez (Bolivia). Jørgensen (2014) also indicated this species from Oruro (Bolivia) on the basis of a misidentified collection that actually corresponds to X. digitatum (Liberman 352, LPB).

Phenology.

Collected in flower in March and November.

Etymology.

It is named after Eric von Rosen (1879-1948), a Swedish aristocrat, explorer, and ethnographer.

Notes.

Xenophyllum rosenii is unique in the genus by its 2-forked leaves. The species has been confused with X. digitatum (e.g., Meneses 5446, LPB; Treviño 761, HSP; Tupayachi 736, US). A detailed study of the leaves highlights that these species can be straightforwardly discriminated from one another by the leaf apex (2-forked in X. rosenii vs. 3-forked in X. digitatum ). The other characters appear to be useless because of a significant overlapping among them.

Since two specimens of the gathering Fries 862 were found at UPS, the lectotypification has been further narrowed to a single specimen by way of a second-step lectotype (UPS-V-833144).

Additional specimens examined.

Bolivia. Potosí: Sur Lípez, San Antonio de Lípez, 21°52'S, 66°56'W, 1966, A.F.G. Cope s.n. (K, US); Sud Lípez, 5.5 mi SW of San Antonio de Lípez (Viejo) on road towards Quetena Grande, 21°52'S, 66°56'W, 20 Mar 1993, P.M. Peterson, R.J. Soreng & S. Laegaard 13040 (US).

Figures

Figure 20. Distribution map of Xenophyllum poposa (left hand), X. lorochaqui (right hand, closed triangle), and X. rosenii (right hand, open circle).