Actinocephalus brevifolius Trovó & Echtern., 2022

Trovó, Marcelo & Echternacht, Lívia, 2022, The Paepalanthoideae (Eriocaulaceae) of the Chapada dos Veadeiros National Park, Brazil: taxonomic novelties, identification key, and illustrated list of species, European Journal of Taxonomy 834, pp. 58-93 : 61-65

Actinocephalus brevifolius Trovó & Echtern. sp. nov.

urn:lsid:ipni.org:names:77302846-1

Figs 2–3 , 6A

Diagnosis

Differs from Actinocephalus phaeocephalus by having rhizomes, narrower rosettes of linear and shorter leaves, more numerous paraclades with linear and shorter bracts, and also by the pilosity of the floral organs.

Etymology

The epithet “ brevifolius ” is related to the species’ small leaf size both when compared to the morphologically similar species and also in relation to the size of its paraclades.

Material examined

Type BRAZIL • Goiás, Alto Paraíso de Goiás , Parque Nacional da Chapada dos Veadeiros , Beira da estrada de terra para a Vereda do Mulungu ; 14°06ʹ26ʹʹ S, 47°39ʹ10ʹʹW; 9 May 2018; M.L.O. Trovó et al. 774; holotype: RB [ RB1405306 ]; isotypes: B, CEN, NY, P, SPF .

Paratypes BRAZIL • Goiás, Alto Paraíso de Goiás ; 13 Nov. 2017; M.L.O Trovó & L.M Borges 688; CEN, RB, SPF • ibid.; 21 Aug. 2018; M.F. Simon et al. 3379; CEN, RB • sibid.; 14 Mar. 2020; L. Echternacht, M. Pignal & P.H. Cardoso 2830; OUPR . • ibid.; 14 Mar. 2020; L. Echternacht, M. Pignal & P.H. Cardoso 2833; OUPR .

Description

Herbs perennial, solitary, 20.0−50.0 cm tall; rhizome short, sometimes sprouting; aerial stem restricted to the rosette, ca 0.5−2.5 cm long. Leaves persistent, membranaceous to chartaceous, linear, greenish, flat, patent to recurved, 0.5−2.0 × 0.05−0.1 cm, with short hairs on both surfaces, margins with short and rarely long hairs, apex acute. Paraclades arising from the leaf axil, ca (1)5−35 per plant, 5.5−15.0 cm long, incurved; paraclade bracts usually persistent, membranaceous to chartaceous, linear, greenish, flat to navicular, patent to rarely recurved, 0.5−1.5 × 0.05−0.2 cm, with short hairs on both surfaces, margins with short hairs, apex acute. Spathes 3.5−5.5 cm long, with short, long, and t-shaped trichomes on the external surface, apex acute. Scapes 1−15 per paraclade, arranged at the paraclade apex, 20.0−45.0 cm long, with short t-shaped trichomes and long hairs, glabrescent. Capitula 0.6−1.2 cm diam., obconic to hemispherical, whitish; involucral bracts in 4−5 series, the internal series surpassing the floral disc, castaneous, elliptical, ca 3.5 mm long, with short hairs on the abaxial surface, densely ciliate, apex long acuminate. Flowers trimerous, ca 40 per capitulum, disposed in concentric rings; floral bracts linear to narrowly oblong, whitish, flat, ca 4.0 mm long, sparsely pilose distally, margin ciliate toward the acute apex. Staminate flowers ca 4.0 mm long; pedicel ca 0.8 mm long; sepals free, linear to narrowly oblong, navicular, whitish to light castaneous, ca 2.5 mm long, pilose distally on the abaxial surface, densely ciliate toward the acute apex; anthophore fleshy, ca 1.0 mm long; petals fused into a tube, whitish, membranaceous, ca 2.0 mm long; stamens ca 2.5 mm long, cream-colored; carpellodes 3, papillose. Pistillate flowers ca 3.5 mm long, pedicel ca 0.05 mm long; sepals free, oblong to obovate, navicular, castaneous, ca 3.5 mm long, pilose distally on the abaxial surface, densely ciliate toward the acute apex; petals free, oblong, flat, whitish, ca 2.5 mm long, pilose distally on the abaxial surface, ciliate toward the acute to obtuse apex; gynoecium 3.5 mm long, stigmatic branches simple, slightly longer than the nectariferous branches, staminodes scale-like. Fruit a loculicidal capsule. Seeds ellipsoid, reddish.

Distribution, habitat, and conservation

A few populations with ca 15−50 flowering individuals of Actinocephalus brevifolius sp. nov. were observed along the margins of unpaved roads in the Chapada dos Veadeiros National Park. All known populations are restricted to the same area in the Rio Preto Valley in the vicinity of the Morro da Baleia Region. Some of these populations are at risk of disappearing, as they occur along roads frequently used by tourists and locals, but at least one population occurs in a less exposed area, close to the Vereda do Mulungu. The individuals were found growing in dry to humid soil along the border of moist grasslands. According to the IUCN (2019) distribution criteria, EN: B1ab (i,ii,iii,iv), and its occurrence inside a National Conservation Unit, the species should be considered Endangered.

Notes

Actinocephalus brevifolius sp. nov. is one of the few species of Actinocephalus occurring in Goiás State ( Sano 2004; Costa & Sano 2013; Andrino et al. 2021). The most similar species to A. brevifolius is Actinocephalus phaeocephalus , the only congeneric and sympatric species in the Chapada dos Veadeiros Region. Although Andrino et al. (2021) refers Actinocephalus phaeocephalus as endemic to the Chapada dos Veadeiros, it is worth mentioning that the species is also distributed southwards, as the type of Actinocephalus phaeocephalus var. foliosus (Moldenke) F.N.Costa & Andrino was collected in the vicinities of Brasília.

Both Actinocephalus brevifolius sp. nov. and A. phaeocephalus are perennial and share the relatively long paraclades bearing very similar obconic to hemispherical capitula surrounded by a series of castaneous involucral bracts with densely ciliate apex surpassing the floral disc. Actinocephalus brevifolius is distinguished by its rhizome (vs rhizome absent); shorter and narrower, linear leaves, 0.5−2.0 × 0.05−0.1 cm (vs lanceolate, 4.0−8.5 × 0.5−0.9 cm); ca 5−35 paraclades per rosette (vs ca 4−8), covered by shorter and narrower, linear bracts, 0.5−1.5 × 0.05−0.2 cm (vs lanceolate, 2.0−5.5 × 0.3−0.5 cm). The flowers are similar, as in most Actinocephalus -related species, but slight differences in pilosity were observed in the floral organs, especially in the petals of the pistillate flower.

Figures

Fig. 2. Actinocephalus brevifolius Trovó & Echtern. sp. nov.. A. Habit. B. Rosette detail. C. Paraclade apex detail. D. Capitulum detail. E. Involucral bract, abaxial surface. F. Floral bract, abaxial surface. G. Staminate flower. H. Staminate flower with sepals removed and corolla opened. I. Pistillate flower. J. Petal of the pistillate flower, abaxial surface. K. Gynoecium. (M.L.O. Trovó et al. 774 – RB).

Fig. 3. Actinocephalus brevifolius Trovó & Echtern. sp. nov. A. Habitat. B. Habitat detail. C. Habit. D. Habit detail. E. Rosette and paraclade detail. F. Spathe detail. G. Capitulum detail, view from above. H. Capitulum detail, view from below.

Fig. 6. Species of Paepalanthoideae (Eriocaulaceae) from the Chapada dos Veadeiros National Park. A. Actinocephalus brevifolius Trovó & Echtern. sp. nov. B. A. phaeocephalus (Ruhland) F.N.Costa. C. Comanthera dimera Echtern.. D. Paepalanthus acanthophyllus Ruhland. E. P. amphibius Trovó. F. P. atratus (Moldenke) L.E.F.Silva & Trovó. G. P. bifidus (Schrad.) Kunth. H. P. campanulatus Trovó.