Philcoxia rhizomatosa Scatigna & V. C. Souza 2015, sp. nov.
Creators: name: Scatigna, André Vito
name: Souza, Vinicius Castro
name: Pereira, Caio Guilherme
name: Sartori, Marcos Aurélio
name: Simões, André Olmos
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Lamiales
Plantaginaceae
Philcoxia
Philcoxia rhizomatosa

description: Philcoxia rhizomatosa Scatigna & V.C.Souza, sp. nov.
Type: — BRAZIL. Minas Gerais: Botumirim, Fazenda Sobrado, 16°54’02”S, 42°53’19”W, 820m, 08 December 2012, fl., Scatigna, A. V. & Sartori, M. A. 319 (Holotype: UEC!; Isotypes ESA!, K!). Figures 1A–I & 2B–E.
Philcoxia rhizomatosa is similar to P. bahiensis in the lenght of the inflorescence but differs by being entirely glabrous (vs. glandular-pubescent). It is also similar to P. minensis in the presence of a rhizome but differs by being thicker and branched (vs. delicate and unbranched). It differs from all other species by its larger leaf blades, reaching up to 7 mm diam. (vs. 1.5–3 mm); thicker wellbranched rhizome with evident nodes; and entirely glabrous inflorescence, pedicel and calyx.
Perennial herb, rhizomatous, inflorescence ascending to erect, ca. 25 cm tall. Rhizome conspicuous, branched, 1.4–2.5 mm thick. Leaves alternate, subterranean when immature and at the soil surface when mature; stipules absent; petiole 0.4–3.7 cm long, glabrous, subterranean; underground blade immature, conduplicate; aerial blade mature, orbicular to reniform, peltate, 0.2–0.7 cm diam.; adaxial surface glandular-pubescent; abaxial surface glabrous, except for some rare trichomes at the margins. Inflorescence a helicoid cyme, 15–30 cm long, glabrous; pedicel 0.5–2.5 cm long at anthesis, glabrous; bracts 1–1.45 mm long, persistent. Calyx with 5 sepals, free, oval, subequal, 0.95–1.1 mm × 0.65–0.69 mm, apex lilac at anthesis, glabrous. Corolla bilabiate, 5-lobed; tube ca. 6 mm long, wider at base, externally sparsely pubescent at dorsal portion, internally glandular-pubescent, yellowish; lobes obovate to orbicular, apex round to slightly emarginate, lateral lobes 4.3–4.5 mm × 3.6–3.7 mm, upper lobe 3.3–3.5 mm × 3.5–3.6 mm, lower lobes 3.9–4.1 mm × 2.9–3.0 mm, lilac. Stamens 2, adaxial, inserted on corolla tube, included; filaments slightly sigmoid, flattened, ca. 0.5 mm long, puberulent on proximal portion; anthers located just below stigma, transversely oriented to the filament, dorsifixed, monothecous. Carpels 2; ovary superior, syncarpous, 2-locular, globose or ovoid, ca. 1 mm long, surrounded by an annular nectary disk; placentation axile, ovules numerous; style terminal, solitary, caduceus, base filiform, 1.25 mm long, apex obdeltoid, curved, 0.75 mm long; stigma bilabiate. Fruits and seeds not seen.
Distribution and habitat:— Philcoxia rhizomatosa is only known from a sand patch in an area of native vegetation, composed of Cerrado and Caatinga, surrounded by an Eucalyptus farm, in the municipality of Botumirim, Minas Gerais. Individuals are distributed at the border of a deep white quartzite sand patch within an area of approximately 2000 m ². Although it is difficult to isolate a single individual from a population, since they are plants with branched rhizomes and propagate vegetatively, at least ten individuals were found in the area. (Fig. 2A).
Phenology:—Plants were collected with flowers in December and March. The population was vegetative in October.
Conservation status:—According to the Guidelines for Using the IUCN Red List Categories and Criteria v.11 (IUCN 2014), this species should be characterized as critically endangered (CR), under sub-criteria D1 and D2, due to few individuals known from only one place. The only population is found at a constantly disturbed sand patch where local people extract sand for housing constructions. Also, the increasing area of Eucalyptus cultivation is a threat to this population.
Etymology:—The specific epithet refers to the conspicuous and thick rhizome with evident nodes, a feature not found in any other species of the genus.
Additional specimen examined (paratype):— BRAZIL. Minas Gerais: Botumirim, Fazenda Sobrado, 16°54’02S, 42°53’19W, 820m, 30 March 2013, fl., Scatigna, A. V. & Cândido, H.G. 374 (UEC!).
Taxonomic notes:— Philcoxia rhizomatosa is easily recognized by the conspicuous and thick rhizome and the larger leaf blades reaching up to 7 mm diam. vs. 1.5–3 mm in other species of the genus. Also, P. rhizomatosa is the only species with entirely glabrous inflorescence, pedicel and calyx (Table 1).
Notes on morphology:—All species of Philcoxia have a particular morphology, with underground stems, branches and what are considered to be petioles. However, the petioles of P. minensis, P. tuberosa and P. rhizomatosa present vegetative buds and, sometimes, branches, which is consistent with the morphology of a stem (Figure 1B, 2E). It is actually unclear what the root system, stems and petioles really are, since no anatomical studies have been done so far. Therefore, it is important that new studies address these questions to help understand the underground system of Philcoxia species. Reproduction of Philcoxia is unclear, although we have observed that P. minensis, P. tuberosa and P. rhizomatosa propagate vegetatively by rhizomes (Fig. 2D).
Test for carnivory:—The presence of several glands similar to those of P. minensis (Guilherme Pereira et al. 2012) and the abundance of nematodes over the leaf blades of P. rhizomatosa suggest that this species is carnivorous (Fig. 2G). The detected activity of phosphatase on the leaves of P. rhizomatosa (Fig. 2F) is consistent with a digestive function and indicates that prey is most likely digested by the plant itself and not due to some mutualistic relationship, as in the case of several pitcher plants (Adams & Smith 1977).
description: Published as part of Scatigna, André Vito, Souza, Vinicius Castro, Pereira, Caio Guilherme, Sartori, Marcos Aurélio & Simões, André Olmos, 2015, Philcoxia rhizomatosa (Gratioleae, Plantaginaceae): a new carnivorous species from Minas Gerais, Brazil, pp. 275-280 in Phytotaxa 226 (3) on pages 276-279, DOI: 10.11646/phytotaxa.226.3.8, http://zenodo.org/record/13631743