Senecio pygmophyllus (S.F. Blake) J.Calvo, A.Granda & V.A.Funk, 2019

Calvo, Joel, Granda, Arturo & Funk, Vicki A., 2019, New combinations and synonyms in discoid caespitose Andean Senecio (Senecioneae, Compositae), PhytoKeys 132, pp. 111-130 : 120-125

publication ID	https://dx.doi.org/10.3897/phytokeys.132.38534
persistent identifier	https://treatment.plazi.org/id/0E069DFA-4C68-51DB-AAB2-94C157EB9832
treatment provided by	PhytoKeys by Pensoft
scientific name	Senecio pygmophyllus (S.F. Blake) J.Calvo, A.Granda & V.A.Funk
status	comb. nov.

Treatment

2. Senecio pygmophyllus (S.F. Blake) J.Calvo, A.Granda & V.A.Funk comb. nov. Figs 3C, D View Figure 3 , 4C, D View Figure 4 , 6 View Figure 6

Werneria pygmophylla S.F. Blake, J. Washington Acad. Sci. 18: 491. 1928. Type: Peru. Moquegua: cordillera East of Carumas, 4500-4600 m, 7-8 Mar 1925, A. We berbauer 7358 (holotype: F [F-552587]; isotypes: CONC [CONC-28864], G [G00356025], US [US00622822]).

Senecio laucanus Ricardi & Martic., Gayana, Bot. 11: 17. 1964. Type: Chile. Arica-Parinacota: camino de Putre a Chucuyo, km 17, 4250 m, 12 Feb 1964, C. Marticorena, O. Matthei & M. Quezada 208 (holotype: CONC [CONC-29864]; isotype: CONC), syn. nov.

Description.

Caespitose perennial herb. Leaves long pseudopetiolate; leaf lamina 2.5-5.5 mm long, 2.4-5.5 mm wide, ovate to suborbiculate, obtuse at the apex, rounded to truncate at the base, typically crenate-lobate with 3-9 rounded lobes, revolute, usually strongly conduplicate downwards, pilose on both surfaces, somewhat fleshy, glaucous; pseudopetiole 5-25 mm long, flat, slightly broadened at the base, marginally ciliate. Capitulum discoid, solitary, terminal, sessile or subsessile; involucre 6-8 mm long, 7-10 mm wide. Involucral bracts 16-21, oblong-lanceolate, 2.5-4 mm long, 0.7-1.7 mm wide, partially fused at the base, smooth, with trichomes on the abaxial surface 0.5-0.8 mm long, dark purple- or blackish-tipped. Supplementary bracts ca. 3, linear, 6-7.5 mm long, 0.5-0.8 mm wide, smooth, three-quarters to as long as the involucral bracts, with trichomes on the margins, dark purple- or blackish-tipped. Disc florets 50-82, 3.5-5.1 mm long, 0.6-1 mm wide, 5-lobed, conspicuously differentiated in a distinct tube and campanulate limb, whitish. Anther bases auriculate, clearly acute, dark purple to blackish; filament collar balusterform. Style branches truncate with a crown of sweeping hairs, dark purple to blackish. Achenes 1.7 –1.8(– 2.5) mm long, ca. 0.5 mm wide, brownish, covered by dense indumentum of obtuse whitish myxogenic twin trichomes ca. 0.2 mm long; pappus 3-4.5 mm long, barbellate, whitish. Chromosome number: unknown.

Additional iconography.

Blake (1928: pg. 496, fig. 1F, G, sub W. pygmophylla ); Ricardi and Marticorena (1964: pg. 19, fig. 6, sub S. laucanus ).

Distribution and habitat.

Chile (Arica-Parinacota, N Tarapacá) and Peru (Moquegua) ( Fig. 5 View Figure 5 ). The species is also expected in the Peruvian department of Tacna and in the Bolivian region bordering northern Chile, although no collections have been studied from there. It grows in exposed places on sandy soils, between elevations of 4100-4700 m.

Phenology.

Collected in bloom from January to June, although full bloom probably takes place between March and April.

Etymology.

The epithet refers to the resemblance of the leaves to a fist.

Discussion.

Blake (1928) placed his new species within Werneria arguing that the involucral bracts were connate half way. Otherwise, he assumed a close similarity between it and a Senecio species collected by Pennell here identified as S. moqueguensis Montesinos (see protologue of W. pygmophylla ). It is certain that the involucral bracts of S. pygmophyllus are usually partially fused at the base; however, this character alone cannot be used as diagnostic to place a species in one or another genus. Rather, we prefer to base a decision on a set of characters, i.e., presence or absence of genuine supplementary bracts, involucral bracts free or fused at the base, achene trichomes myxogenic or not, and rosettiform or caespitose habit. Accordingly, we consider that this species should be placed within Senecio on the basis of the following characters: presence of supplementary bracts, myxogenic achene trichomes, and caespitose habit. This decision is also supported by the fact that it was inaccurately considered a synonym of S. digitatus for a long time.

Rockhausen (1939) was the first author who treated W. pygmophylla as a heterotypic synonym of S. digitatus . Since then, most authors followed his treatment (e.g., Cabrera 1949; Freire et al. 2014). Ricardi and Marticorena (1966), in disagreement, concluded that they correspond to two distinct taxonomic entities. We agree with Ricardi and Marticorena’s treatment after studying the respective type materials, further collections from southern Peru and northern Chile, and living plants. The two species can be differentiated by their leaf shape and indumentum type. Senecio pygmophyllus has a lamina clearly differentiated from the pseudopetiole (petioliform base); usually the lamina is remarkably reduced when compared with the pseudopetiole length (at least in the more basal leaves). The lamina we observed were ovate to suborbicular, typically crenate-lobate with 3-9 rounded lobes and revolute margins ( Fig. 4C View Figure 4 ). In contrast, S. digitatus has linear to slightly spatulate leaves narrowed at the base ( Fig. 3E, F View Figure 3 ). This latter species is extremely variable with regard to the leaf margin, which can be dentate, pinnatipartite or distantly pinnatisect, with clearly acute teeth; however, specimens with entire leaves and even individuals displaying both entire and dentate leaves were occasionally observed. The leaf apex is acute and usually shows a whitish callus-like tip, whereas in S. pygmophyllus the apex is always plainly obtuse and unadorned ( Fig. 3C View Figure 3 , 4D View Figure 4 ). Both species usually have abundant indumentum on the leaves, involucre, and supplementary bracts but the type of trichomes differs and is useful to separate them from one other. The indumentum of S. pygmophyllus is pilose whereas in S. digitatus the trichomes are clearly arachnoid, longer, and intermingled. Moreover, the indumentum of S. digitatus is essentially concentrated on the adaxial surface, whereas in S. pygmophyllus the leaf lamina has trichomes on both surfaces. Their distribution areas do not overlap ( Fig. 5 View Figure 5 ).

Senecio pygmophyllus might be confused with those forms of S. melanandrus displaying pilose, dentate leaves. A useful character to discriminate them from each other is the leaf shape, although some overlap has been detected in a few specimens. In S. pygmophyllus the leaves are clearly pseudopetiolate and the ratio lamina/pseudopetiole length usually is very low in the more basal leaves ( Fig. 4D View Figure 4 ). In contrast, S. melanandrus displays a lamina progressively narrowed at the base ( Fig. 3B View Figure 3 ). The distinctive pseudopetiole length of S. pygmophyllus might be an adaptation to the sandy soils where this species thrives because the plants usually appear to be partially sunken. Additionally, the number of disc florets tends to be higher in S. pygmophyllus (50-82 vs. 20-45), as well as the number of involucral bracts (16-21 vs. 11-16). Since the mentioned morphology coincides with geographical separation, we consider it appropriate to recognize it as a distinct species.

The name S. laucanus Ricardi & Martic. was described from northern Chile (Arica-Parinacota) and it was hitherto considered endemic to this country ( Moreira-Muñoz et al. 2016). It is included in the synonymy of S. pygmophyllus since we failed to identify any diagnostic character to differentiate them. In some specimens from Chile the more basal leaves are not so long pseudopetiolate as in the typical forms (e.g., Moreira-Muñoz & Luebert 2470), but it is considered as part of the variability encompassed by this species; indeed, this morphology probably responds to the fact that these plants grow on less sandy soils.

Specimens examined.

Senecio digitatus . ARGENTINA. Salta: Los Andes, Huaitiquina, 23°44'S, 67°12'W, 27 Feb 1972, Cabrera et al. 22559 (LP). BOLIVIA. Potosí: Sud Lípez, a 1 km al W de salar Chalviri, 22°30'S, 67°38'W, 7 May 1999, N. Massi & C. Salles 726 (LPB) [first record for Bolivia]. CHILE. Antofagasta: El Loa, camino entre Ascotán y San Pedro de Conchi, 21°58'S, 68°26'W, 4 Apr 1985, M. Arroyo 85-606 (CONC); El Loa, cerro Losloyo, ladera SE, 23°9'S, 67°15'W, 9 Apr 1997, M. Arroyo, L. Cavieres & A. Humaña 97331 (CONC); El Loa, cerro Nevados de Poquis, ladera SO, 23°4'S, 67°5'W, 9 Apr 1997, M. Arroyo, L. Cavieres & A. Humaña 97343 (CONC); El Loa, pampa Laguna Helada, 23°6'S, 67°5'W, 9 Apr 1997, M. Arroyo, L. Cavieres & A. Humaña 97403 (CONC); El Loa, pampa Loyoques, 23°11'S, 67°12'W, 9 Apr 1997, M. Arroyo, L. Cavieres & A. Humaña 97408 (CONC); El Loa, cordón cerro de la Pacana, cuesta entre salar de Aguas Calientes y quebrada Quepiaco, 23°3'S, 67°29'W, 11 Apr 1997, M. Arroyo, L. Cavieres & A. Humaña 97477 (CONC); El Loa, cordón cerro de la Pacana, cuesta entre salar de Aguas Calientes y quebrada Quepiaco, 23°4'S, 67°30'W, 11 Apr 1997, M. Arroyo, L. Cavieres & A. Humaña 97498 (CONC); El Loa, Toconao, camino a Tara, monjes de La Pacana, 23°3'S, 67°29'W, 6 Mar 2019, J. Calvo 7926 (SGO); cruce camino internacional Paso Jama con camino a salar de Tara, 23°3'S, 67°29'W, 19 Dec 1996, A. Moreira-Muñoz 317 (SGO); Machuca-Copacoya, 22°28'S, 68°2'W, 18 Feb 1885, F. Philippi s.n. (LP, SGO); laguna de Llaillai, 21°55'S, 68°12'W, 23 Feb 1885, F. Philippi s.n. (CONC, LP, SGO, SI); El Loa, Ascotán, 21°27'S, 68°21'W, 23 Jan 1943, E. Pisano & J. Venturelli 1753 (SGO); El Loa, entre Machuca y Tatio, 15 Feb 1943, E. Pisano & J. Venturelli 1866 (CONC, SGO); Tarapacá: [without locality], Feb 1885, F. Philippi s.n. (K); Iquique, Collaguasi, San Carlos, 20°58'S, 68°41'W, 22 Jan 1994, S. Teillier 3286A (CONC).

Senecio pygmophyllus . CHILE. Arica-Parinacota: cerca de laguna de Cotacotani, camino a Guane Guane, 18°10'S, 69°14'W, 9 Mar 1984, M. Arroyo 84-724 (CONC); portezuelo entre cerro Guane Guane y cerro Larancagua, 18°9'S, 69°19'W, 22 Apr 1984, M. Arroyo 84-935 (CONC); Las Cuevas, antes del Chaku, 18°11'S, 69°25'W, 20 Mar 2015, A. Moreira-Muñoz & F. Luebert 2470 (SGO); camino de Putre a Portezuelo de Chapiquiña, 18°20'S, 69°30'W, 28 Mar 1961, M. Ricardi, C. Marticorena & O. Matthei 277 (CONC); Tarapacá: Colchane, géiser Puchultiza, 100 m antes del géiser, 19°24'S, 68°57'W, 16 Jun 2018, A. Moreira-Muñoz 2876 (SGO). PERU. Moquegua: minera Quellaveco, 17°6'S, 70°36'W, 8 Apr 1999, ESCO 7238 (US); area between the carretera-binacional and the interoceanica sur, on unpaved road that connects the two main roads and borders a large bofedal, 16°51'S, 70°32'W, 12 Mar 2014, V.A. Funk, M. Diazgranados & E. Cochachin 13153 (US, USM); Mariscal Nieto, Carumas, Ancolacaya, 16°38'S, 70°19'W, Mar–Apr 2018, V. Morales 140 (USM); 5 km East of lago Suche, 16°55'S, 70°19'W, 19 Jan 1952, O.P. Pearson 5 (CONC, UC).