Pentacalia ochracea J. Calvo & H. Beltrán, 2018

Calvo, Joel & Beltrán, Hamilton, 2018, Two new species of Pentacalia (Senecioneae, Compositae) from Peru, Phytotaxa 357 (4), pp. 284-290 : 288-289

2. Pentacalia ochracea J. Calvo & H. Beltrán , sp. nov. ( Fig. 3 )

Type: — PERU. Amazonas: provincia Luya, distrito Camporredondo, 30 June 2001, J. Campos 6826 (holotype: USM 302023 ; isotypes: HUT, MO, QCA) .

Pentacalia ochracea can be readily distinguished by the combination of the following characters: synflorescence mainly terminal, capitula discoid, long-pedicellate, abaxial leaf surface densely and persistently ochraceous-arachnoid, involucre 7–8 mm long covered by ochraceous-lanate indumentum.

Scandent woody vines. Stems terete, furrowed, with evanescent arachnoid-floccose indumentum, solid. Leaves alternate, chartaceous, not reflexed; lamina elliptic, 6–9.5 cm long, 2.5–3.8 cm wide, acute to mucronate, obtuse to rounded at base, entire, plane, adaxial surface glabrous, lustrous, with tertiary venation conspicuous on dry specimens, abaxial surface densely and persistently ochraceous-arachnoid, with secondary venation somewhat protruding; petiole 0.8–1.1 cm, arachnoid-floccose to lanate. Synflorescences mostly terminal, broadly paniculiform-thyrsoid, lax, with reduced linear bracts at the base of each synflorescence branch (foliose the basal ones); synflorescence branches with evanescent arachnoid-floccose indumentum; capitula discoid, on pedicels 7–21 mm long, with a few bracteoles. Involucre cylindrical, 7–8 mm long, 3.5–3.8 mm wide, covered by ochraceous-lanate indumentum. Involucral bracts 8, 6.6–7.2 mm long, 1.2–2 mm wide, lanate, herbaceous; supplementary bracts 4–6, 3.5–4.5 mm long, 0.4–0.7 mm wide, a half as long as the involucral bracts, with lanate indumentum. Bisexual florets 10–12, 7.6–9 mm long, 5-lobed, with lobes subulate-triangulate, ca. 1 mm long. Anther bases long-sagittate, longer than the filament collar. Style-branches truncate with a crown of sweeping trichomes. Achenes 3.6–4.5 mm long, 0.8–0.9 mm wide, cylindrical, 6–8-ribbed, straw-yellow, glabrous; pappus 7.3–8.2 mm long, barbellate, white. Chromosome number: unknown.

Distribution and habitat: —Until now, P.ochracea is known from a single locality in the district of Camporredondo, in the basin of the Marañón river (southwestern Amazonas Department; figure 2). It grows in Andean humid montane forests.

Phenology: —It was collected in bloom in June.

Etymology: —The epithet ochracea refers to the characteristic ochraceous-lanate indumentum of the involucre.

Discussion: —Among the discoid species of Pentacalia , the new species is characterized by having terminal synflorescences, long-pedicellate capitula, ochraceous-lanate indumentum covering the involucre, and entire leaves.

Pentacalia chachapoyensis ( Greenman 1938: 801) Cuatrecasas (1981: 245) is another species with discoid, pedicellate capitula, and mainly terminal synflorescences that also thrives in southern Amazonas Department. They can be readily differentiated by the indumentum of the involucre (glabrous or almost so in P. chachapoyensis vs. lanate in P. ochracea ), and the leaf margin and indumentum (denticulate to subentire, glabrous in P. chachapoyensis vs. entire, densely arachnoid beneath in P. ochracea ). Moreover, the new species has longer pedicels and laxer synflorescences.

In southern Ecuador, there is a species with discoid capitula, terminal synflorescences, and indumentum on both the involucre and the abaxial leaf surface, i.e., P. gibbiflora (Cuatrecasas 1954: 42) Cuatrecasas (1981: 246) . However, this latter species displays sessile, clustered capitula, shorter involucre, and weakly mucronate-denticulate leaves. Any confusion with it or the other members of the genus is very improbable.

Figures

FIGURE 3. Holotype of Pentacalia ochracea (USM 302023).