Murdannia engelsii M.Pell. & Faden, 2016

Pellegrini, Marco Octavio de Oliveira, Faden, Robert B. & Almeida, Rafael Felipe de, 2016, Taxonomic revision of Neotropical Murdannia Royle (Commelinaceae), PhytoKeys 74, pp. 35-78 : 44-47

2. Murdannia engelsii M.Pell. & Faden sp. nov. Figs 2 , 10

Diagnosis.

Similar to Murdannia paraguayensis due to its deflexed pedicels at post-anthesis and when fruiting; petals with minute glandular hairs at base on the adaxial surface; filaments, ovaries, styles and capsules with minute glandular hairs, and capitate stigma. It can be differentiated by its trailing stems, distichously-alternate leaves, inflorescence reduced to a solitary cincinnus, peduncles with a mixture of eglandular and glandular hairs, cincinni 2-7-flowered, capsules broadly ovoid to broadly ellipsoid, and 1-seeded locules.

Type.

BRAZIL. Mato Grosso: Itaúba, Resgate de Flora da UHE Colíder, lote G de supressão, 260 m, floresta do Planalto dos Parecís, prainha arenosa no rio Teles Pires , fl., fr., 27 May 2015, M.E. Engels et al. 3474 (holotype: RB!; isotypes: CNMT!, HERBAM!, MBM!, US!, TANG!).

Description.

Herbs ca. 10.0-36.0 cm tall, perennial, rhizomatous without a definite base, terrestrial to paludal in river banks. Roots thin, fibrous, brown, densely to sparsely pilose with hyaline hairs, emerging from the basalmost nodes and rhizome. Rhizomes long, trailing, light brown to light green, shallowly buried in the sand. Stems ascending to erect, thin, herbaceous to slightly succulent, usually densely branched or branched only at the base, sometimes branching from the upper nodes; internodes 1.3-3.5 cm long, green, with a mixture of eglandular (scabrid) and glandular hairs, becoming glabrous with age, with a line of eglandular hairs opposite the leaf above, hairs hyaline. Leaves distichously-alternate, evenly distributed along the stems, rarely somewhat congested at the apex of the stems, the distal ones gradually smaller than the proximal ones; sheaths 2-2.5 mm long, green, with glandular hairs, becoming glabrous with age, hairs hyaline, margins sparsely ciliate, with a line of eglandular hairs opposite the leaf above, hairs hyaline; lamina (0.5-)1.6-6 × 0.3-1 cm, membranous, generally conduplicate, rarely flat, slightly falcate to falcate, green on both sides, drying olive-green on both sides, narrowly elliptic to narrowly lanceolate or narrowly ovate, glabrous on both sides or the uppermost usually with glandular hairs at least basally, base amplexicaul, margins green, ciliate to setose at base or the uppermost sometimes with glandular hairs, apex acuminate; midvein slightly conspicuous, slightly impressed adaxially, prominently acute abaxially, secondary veins 2(-3) pairs, inconspicuous to slightly conspicuous on both sides, dark green. Inflorescences 1-2-(5), terminal or axillary from the uppermost nodes, consisting of a solitary cincinnus; peduncles 1-1.4 cm, with a mixture of eglandular (scabrid) and glandular to densely glandular hyaline hairs; basal bract reduced, 5-5.5 × 4-4.5 mm, lanceolate to ovate, adaxially glabrous, abaxially glabrous or with glandular hairs, base amplexicaul, margins ciliate at base, apex acute, veins inconspicuous on both sides, dark green; cincinni 2-7-flowered, erect, straight, peduncle 3.5-8 mm long, green, with glandular to densely glandular, hyaline hairs, cincinnus internodes 4.5-8 mm long, green, with glandular to densely glandular hyaline hairs; cincinnus bract and bracteoles ca. 1-1.5 × 0.9-1 mm, persistent, ovate, flat, light green, with a sparse mixture of eglandular (scabrid) and glandular hairs near the base, base amplexicaul, non-perfoliate, margins glabrous, apex acute. Flowers bisexual or male, enantiostylous, 1-1.4 cm diam.; floral buds ovoid, 2.8-3.1 × 2.5-3 mm, green; pedicels 1-6 mm long, green, with glandular to densely glandular, hyaline hairs, deflexed and slightly elongate in fruit; sepals 3-3.5 × 0.5-0.8 mm, triangular to ovate-triangular, cucullate, green, with glandular to densely glandular, hyaline hairs, apex acute, margins hyaline light green; petals equal, 4.5-7.3 × 2.5-4.5 mm, obtrullate, rarely obovate, slightly cucullate, pale lilac to lilac, mauve or pink, rarely white, with minute glandular hairs at the base on the adaxial surface, base cuneate, margins entire, apex obtuse to rounded; stamens 3, equal, filaments basally with minute glandular hyaline hairs, gently curved in the middle, 4.1-5.9 mm long, pale lilac to lilac or white, anthers elliptic, 0.6-0.7 × 0.3-0.7 mm, connective white to lilac, anthers sacs white to pale lilac, pollen white; staminodes 3, equal, filaments with minute glandular hyaline hairs, straight, 1.3-1.7 mm long, white to pale lilac, antherodes subsagittate to subcordate, 0.9-1.0 × 0.9-1.0 mm, connective golden yellow, lobes conspicuous, cream-colored to pale yellow; ovary ovoid to ellipsoid, 0.9 × 0.7-0.8 mm, 3-locular, white to light green, smooth, with minute glandular hyaline hairs, style curved at the apex, ca. 3.6-8 mm, white to pale lilac or lilac, stigma capitate, white to lilac. Capsules 3-locular, 3-valved, 3.2-4.5 × 2-2.5 mm, broadly ovoid to broadly ellipsoid, apiculate due to persistent style, light brown when mature, with minute glandular hyaline hairs, sometimes glabrescent with age, smooth. Seeds 1 per locule, 1.8-2.0 × 1-1.2 mm, reniform to broadly ellipsoid, cleft towards the embryotega, ventrally flattened, testa medium to dark brown, sparsely farinose, scrobiculate to shallowly scrobiculate, with ridges radiating from the embryotega, sometimes with 4-7 ventral furrows, with a tan appendage that extends ventri-laterally to the embryotega and basally into the hilum; embryotega semilateral to semidorsal, relatively inconspicuous, generally covered by a cream farina, without a prominent apicule; hilum linear, approximately the same length as the seed, in a shallow depression.

Specimens seen

(paratypes). BRAZIL. Mato Grosso: Itaúba, resgate de Flora da UHE Colíder, Lote G de supressão, floresta do Planalto dos Parecís, região de ecótono entre a Floresta Amazônica e Cerrado, 3 Jun 2016, M.E. Engels & A.S. Bezerra 4510 (HERBAM, MBM, RB); Poconé, rodovia Transpantaneira, 17 May 1983, J. Barcia et al. 1560 (R); loc. cit., Fazenda Nova Berlim, Transpantaneira highway, km 85, 3 May 1992, M. Schessl 2602b (CH, UFMT, ULM, US); loc. cit., highway Poconé-Porto Cercado, 30 May 1992, M. Schessl 2631g (CH, CPAP, UFMT, ULM, US); loc. cit., estrada para Porto Cercado, km 18, 22 Apr 1993, A.L. Prado 2017 (UEC, UFMT); loc. cit., Fazenda Ipiranga, 8 May 1993, A.L. Prado & R. Ribeiro 2045 (HURB, UEC, UFMT); loc. cit., Fazenda Ipiranga, Pousada Piuvial, vazante da sede, km 11 da rodovia Transpantaneira, 20 May 1996, V.J. Pott et al. 3186 (CPAP, US); Vila Bela da Santíssima Trindade, Parque Estadual Serra de Ricardo Franco, margem do rio Guaporé, 23 May 1978, P.G. Windisch 1863 (RB); Mato Grosso do Sul: Corumbá, Fazenda Caceres, próximo da sede de Nhecolândia, 12 Aug 1988, V.J. Pott et al. 595 (CPAP, MBM, US); loc. cit., Fazenda Alegria, Nhecolândia, 30 Jul 1989, A. Pott et al. 4912 (CPAP, MBM, US); loc. cit., próximo ao mata burro na divisa com Retiro Mandovi, Nhecolândia, 3 Aug 1999, V.J. Pott & A. Rodrigues 3993 (CPAP, US); Tocantins: Pium, Ilha do Bananal, Parque Nacional do Araguaia, base física do rio Javaés, antigo acampamento do Projeto Quelônios do Amazônia, 27 Mar 1999, M. Aparecida da Silva et al. 4167 (IBGE, RB).

Etymology.

The epithet honors the collector of the holotype, the Brazilian botanist Mathias Erich Engels, Orchidaceae taxonomist and dear friend of the authors.

Distribution and habitat.

Murdannia engelsii is endemic to Brazil, being known from the states of Tocantins, Mato Grosso and Mato Grosso do Sul (Fig. 10 ). It grows in shady to open sandy river banks of the Amazon, Cerrado and Pantanal domains. Its prostrate stems produce dense mats, generally near rocks and grasses.

Phenology.

It was found in bloom and fruit from March to August.

Conservation status.

Murdannia engelsii possesses both a wide EOO (ca. 514,893.048 km2) and a wide AOO (ca. 15,000.000 km2). Following the IUCN recommendations ( IUCN 2001), Murdannia englesii should be considered Least Concern. Nevertheless, most of the known populations of Murdannia engelsii are in areas currently being deforested and turned into pasture sites for cattle. We believe that this species is highly affected by human activity and should be considered Vulnerable [VU, A2cd+ B2ab(ii, iii,v)+D2].

Discussion.

Murdannia engelsii is morphologically similar to Murdannia burchellii , Murdannia gardneri and Murdannia paraguayensis due to indumentum and flower morphology, and also similar to Murdannia paraguayensis due to the deflexed pedicels in fruit. However, Murdannia engelsii can be easily differentiated by its inflorescence reduced to a solitary cincinnus (vs. thyrsi with several, verticillate or alternate to subopposite cincinni). It can be easily differentiated from Murdannia burchellii and Murdannia gardneri by inflorescence morphology, position of the pedicels at post-anthesis and in fruit, by the indumentum of the filaments, gynoecium and capsules, and seed morphology. Murdannia engelsii is much more similar to Murdannia paraguayensis , due to several key characters. These are the only species in the genus to have petals with minute glandular hairs at the base on the adaxial surface, androecium and gynoecium with glandular hairs, and the only Neotropical species to have pedicels deflexed post-anthesis and in fruit. Nevertheless, Murdannia engelsii can be differentiated by its trailing habit (vs. erect in Murdannia paraguayensis ), leaves distichously-alternate (vs. spirally-alternate), inflorescence reduced to a solitary cincinnus (vs. inflorescence with several verticillate cincinni), cincinni 2-7-flowered (vs. 1-flowered), capsules broadly ovoid to broadly ellipsoid (vs. oblongoid to broadly oblongoid), and locules 1-seeded (vs. 2-seeded). Murdannia engelsii can also be confused with Murdannia nudiflora , due to their small stature, phyllotaxy and inflorescence morphology. However, they can be easily differentiated by its erect cincinni (vs. pendulous), persistent bracteoles (vs. caducous), corolla actinomorphic (vs. zygomorphic), three stamens and three staminodes (vs. two stamens and four staminodes), filaments with minute glandular hairs (vs. bearded with moniliform hairs), and locules 1-seeded (vs. locules 2-seeded) (Table 1 ). One of the most striking features of Murdannia engelsii would be occasional production of several inflorescences clustered towards the apex of a shoot, forming a synflorescence. This synflorescence resembles a single inflorescence with several alternate cincinni.

Figures

Figure 2. Murdannia engelsii M. Pell. & Faden. A Sandy banks of rio Teles Pires, white arrow showing a subpopulation of Murdannia engelsii B detail of the stem, showing the conduplicate and falcate leaves, with amplexicaul bases C detail of the inflorescence, showing the deflexed pedicels at post-anthesis D side view of a male flower, showing the short and bent style. E front view of a bisexual flower, showing the long curved style F detail of a young fruit, showing the pedicel and sepals with glandular hairs, gently curved style and capitate stigma G-J seeds: G dorsal view of a seed, showing the scrobiculate and cleft testa, and the semilateral embryotega H ventral view of the same seed, showing the ventral furrows and tan appendage surrounding the hilum I dorsal view of another seed, showing the shallowly scrobiculate and slightly cleft testa, and the semidorsal embryotega J ventral view of the same seed, with the appendage removed, showing the linear hilum in a shallow depression. K, dorsal view of a seed, showing the smooth testa. Photographs A-F by M. E. Engels, G-J by R. F. Almeida.

Figure 10. Distribution map of Neotropical Murdannia Royle. Full circles Murdannia burchellii Full stars Murdannia engelsii Triangles Murdannia gardneri Stars Murdannia paraguayensis Full squares Murdannia schomburgkiana Squares Murdannia semifoliata.