Paepalanthus hirtellus Trovó, Echtern. & Sano, 2011

Trovó, Marcelo, Echternacht, Livia & Sano, Paulo Takeo, 2011, Paepalanthus hirtellus, a new species of Paepalanthus subsection Actinocephaloides (Eriocaulaceae) from Minas Gerais, Brazil, Phytotaxa 15, pp. 26-32 : 27-31

Paepalanthus hirtellus Trovó, Echtern. & Sano , sp. nov. ( Figs. 1 , 2 )

Ab Paepalantho chrysophoro foliis basis cordatis et latioris (0.5–1.0 cm × 0.2–0.3 cm), scapis brevioris (12–15 cm × 30–40 cm), capitulis brevis (4–6 mm × 7–10 mm) et bracteis involucralibus nigrescentes differt.

Type:— BRAZIL. Minas Gerais: Santo Antonio do Itambé, Parque Estadual do Pico do Itambé, ao longo do começo da trilha para o Pico do Itambé , 1381 m, 18°24’07’’ S, 43°18’50’’W. 12 July 2008, Echternacht & Bastos 1772 (holotype SPF, isotypes B, BHCB, P) .

Perennial herbs, 20–90 cm tall. Stems 5–75 cm long, elongate, ramified at the base or not, glabrous. Leaves spirally arranged along the stem, 2.5–4.5 × 0.5–1.0 cm, lanceolate, flat, patent, rigid, bases cordate, margins densely ciliate, apices acute, hirtellous on both surfaces with long trichomes; spathes 4.0– 5.5 cm long, hirtellous, ciliate towards the apex, apices acute. Scapes verticillate, 20–90 per whorl, 12–15 cm long, glabrous; capitula 4–6 mm in diameter, hemispherical, white; involucral bracts in 3–4 series, ca. 3 mm long, ovate, blackish, pubescent in the central-apical area on the abaxial surface, ciliate towards the apex, apices obtuse; receptacles hemispheric, pubescent. Flowers 3-merous, ca. 40 per capitulum, capitula with 3× more staminate than pistillate flowers; floral bracts ca. 3 mm long, obovate, glabrous, ciliate towards the apex, apices acute; staminate flowers ca. 3 mm long; pedicel ca. 1 mm long, with long trichomes; anthophore present; sepals fused at the base, ca. 2 mm long, obovate, glabrous, ciliate towards the apex, apices obtuse to mucronulate; corolla ca. 1 mm long, tubular, 3-lobed, membranaceous, hyaline; stamens ca. 1 cm long; pistillodes 3, papillose. Pistillate flowers ca. 3 mm long, sessile to short pedicellate; sepals ca. 3 mm long, oblong, hairy abaxially, ciliate towards the apex, apices acute; petals ca. 3 mm long, oblong, hairy abaxially, ciliate towards the apex, apices acute; gynoecium ca. 3 mm long, stigmatic branches bifid at apex, twice as long as the nectariferous branches; staminodes 3, scale-like. Fruit a loculicidal capsule.

Distribution and ecology:—The species is known from a single population found in the municipality of Santo Antonio do Itambé ( Fig. 3 ). Populations of more than 50 individuals were observed in Pico do Itambé State Park. These plants occur usually in the campos rupestres and in the edge of the adjacent Atlantic forest. They grow in the shadow of shrubs and trees, as well as in open areas, on rocky-sandy soils.

IUCN Red List category:— Paepalanthus hirtellus appears to be restricted to a single mountain, with populations and individuals occurring relatively close to each other. Thus, according to criterion B1a (IUCN 2001), this species should be listed as critically endangered.

Etymology:—The epithet refers to the pilosity of the spathes, which is unique in P. subsection Actinocephaloides and rare in other Paepalanthus .

Notes:— Paepalanthus hirtellus is assigned to P. subsection Actinocephaloides based mainly on its trimerous flowers and elongated stems, that are rarely branched at the base (when sterile), bearing scapes arranged in an apical inflorescence (in a single season). It is easily distinguished from the remaining species of this group by its broad leaves with cordate bases, hirtellous spathes, glabrous scapes and blackish involucral bracts. As previously discussed, the distinction between P. subsection Polyactis and P. subsection Actinocephaloides seems ambiguous, relying on a few variable characters. Thus, it does not come to a surprise that P. hirtellus is morphologically similar to species of both groups.

Paepalanthus chrysophorus Silveira (1928: 176) is the species morphologically most similar to P. hirtellus , but that species has been assigned to P. subsection Polyactis . Both species have an elongated stem that may ramify at the base. They also share the rigid ciliate, 2–5 cm long leaves. The leaves are hairy and patent. Other similar features are found in the scapes that are glabrous. Paepalanthus hirtellus can be easily distinguished by its broader leaves (0.5–1.0 cm) with cordate bases (vs. 0.2–0.3 cm, with truncate base), shorter scapes (12–15 cm vs. 30–40 cm), narrower capitula (4–6 mm vs. 7–10 mm), longer stems (20–90 cm vs. 2–30 cm), and blackish involucral bracts (vs dark brown). Paepalanthus chrysophorus is distributed in the northern Espinhaço Range in Minas Gerais, between São Gonçalo do Rio Preto and Grão-Mogol. In both localities, individuals occur on sandy-rocky soils on riverbanks. Paepalanthus hirtellus and P. chrysophorus are most likely allopatric in distribution.

Another species morphologically similar to P. hirtellus is P. lombensis Silveira (1928: 180) both belonging to P. subsection Actinocephaloides. Similar to P. hirtellus and P. chrysophorus , this species has an elongated stem with ciliate, 2–5 cm long leaves. It shares the length of the spathes (4–6 cm) and the size of the capitula (4–6 mm) with the former, but P.hirtellus is readily distinguishable by its longer stems (20–90 cm vs. 2–25 cm), rigid and patent leaves (vs. membranaceous and suberect leaves), abaxially hairy leaves (vs. abaxially glabrous leaves), broader leaves (0.5–1.0 cm) with cordate bases (vs. 0.2–0.3 cm with truncate base), glabrous scapes (vs. pilose scapes), blackish involucral bracts (vs. brown involucral bracts) and glabrous sepals of the pistillate flowers on the abaxial surfaces (vs. hairy on abaxial surfaces at apex). Paepalanthus lombensis is known exclusively from a single collection from Pico do Itambé, without any precise information. As Pico do Itambé represents a large mountain area, it is not possible to state whether the two species occur sympatrically or not.

Figures

FIGURE 1. Paepalanthus hirtellus. A. Habit. B. Spathe detail. C. Capitulum detail. D. Involucral bract abaxial surface. E. Floral bract abaxial surface. F. Staminate flower. G. Staminate flower with sepals removed and open corolla. H. Pistillate flower. I. Gynoecium. Based on Echternacht & Bastos 1772, illustrated by Klei Sousa.

FIGURE 2. Photographs of Paepalanthus hirtellus. A. Habit. B. Verticillate inflorescences detail. C. Young capitula detail. D. Leaves detail. Scale bars: A. 5 cm. B. 4 cm. C. 1 cm. D. 3 cm. Photographs taken by Livia Echternacht.

FIGURE 3. Distribution map of Paepalanthus hirtellus.