Grias portillae Cornejo, 2023

Cornejo, Xavier, 2023, Grias portillae (Lecythidaceae): A new tree species from northwestern Ecuador, Phytotaxa 625 (2), pp. 211-219 : 212-216

Grias portillae Cornejo , sp. nov. ( Figs. 1 , 2 )

Diagnosis: —Species nova monocaulis, inflorescentia caulina cum rhachi brevi, floribus cum petalis atropurpureis, sub anthesi erectis vel paulo divergentibus, filamentis coalescentibus tubum staminalem distinctum formantibus, antheris oblongi, rotundati versus apicem et disco intrastaminato praesenti, affinis Grias theobromicarpa Cornejo & S.A. Mori , a qua folia petiolata cum apice caudata, corolla purpurea, stamina 18–21, 1-verticillata differt.

Type: — ECUADOR. Imbabura: Lita, Río Cristal , c. 0°48’N 78°24’W, 1200 m, 3 Jul 2023 (fl), J. Portilla s.n. (holotype: GUAY!; isotype: QCA!) .

Description: —Unbranched pachycaulous tree, to c. 8 m tall and 15 cm dbh, the trunk cylindric to base. Cataphylls unknown. Leaves clustered at apices of branches; petioles 5–13 cm long, abaxially suborbicular and ± wavy in cross-section, the cross-section with lower arc of 5–6 major transversally elliptic bundles, and upper arc of 1 row of 8–10 minor bundles, the pulvini brown; blades oblanceolate, 100–130 × 25–35 cm, coriaceous, glabrous, green adaxially, paler green abaxially with abundant dark brown punctations, the base long tapering and finally narrowly cuneate, the margins entire with spaced dark brown colleters, the apex shortly caudate, laterally curved; venation brochidodromous, the midrib carinate adaxially, longitudinally sulcate and abundant dark brown to whitish punctate abaxially, the secondary veins in c. 45 pairs in mature leaves, salient, ± carinate adaxially and abaxially, the tertiary veins finely percurrent, scalariform, joining the secondaries at 90° angles, the higher order venation obscure. Inflorescences cauline in middle of trunk, the racemes reduced, the rachis 5–14 × 2–3 mm, bearing up to 3 flowers; pedicel 3–4 × 1.2–2 mm, glabrous, subtended by an ovate to ovate-triangular bract, 2–3 × 2–2.5 mm, with 2, small (c. 1.2 × 0.5 mm), caducous bracteoles inserted c. 3 mm above articulation. Flowers 2–4 cm diam. at anthesis, when petals oriented upwards to somewhat spreading, 7–8 cm when artificially spread horizontally; calyx splitting in 2–4 usually cucullate lobes, the lobes 5–8 × 5–10 mm, glabrous, light-green; petals ovate to ovate-lanceolate or ovate-elliptic, erect to slightly spreading at anthesis, rounded to obtuse and erect to somewhat reflexed outwards at apex, 2.5–3 × 1.5–2.2 cm (slightly smaller, 2.2–2.7 × 1.4–2 cm, when dry), carnose (when fresh, but thinly papyraceous or membranaceous when dried), glabrous, dark purple from bud to anthesis; androecium actinomorphic, creamish-white, the filaments laterally fused over half of their length to form a fleshy oblate staminal tube, c. 7 × 13–14 mm (c. 5 × 10 mm when dry), the tube creamish-white, smooth, the stamens 18–21, inserted in one level on rim, the free part of filaments c. 4 mm long, reflexed downwards, creamish-white, laterally flat, angled, tapered into anthers, the anthers triangular-oblong, c. 2 mm long (c. 1.5 mm when dry), laterally compressed, the thecae much smaller than the connectives, with longitudinalventral dehiscence, rounded at apices, the connective cucullate, with lateral flaps covering most of the smaller thecae; ovary inferior, turbinate, 5–7 × 4 mm (3–5 × 2–3 mm when dry), greenish and glandular outside, glabrous, the summit truncate, with an intrastaminal disc, 0.2–0.3 mm high, with a shallow depression between disc margin and style, the style linear, pink to purplish, c. 1.2 mm tall; ovary 4-locular, the ovules pendulous from upper half of septum, the funicle shortly linear. Fruits and seeds not seen.

Discussion: —The floral traits of androecium structure and arrangement of petals allow the species of Grias to be recognized in two groups. Species of the first group have flowers whose filaments are free for most of their length and fused at base, forming a basal ring, reduced connectives, and suborbicular to broadly elliptic anthers. As the filaments are free for half to most of their length, the short staminal ring that rest on the receptacle is hidden by petals at base, and the androecium apparently bears entirely free filaments from lateral and adaxial views. Also, the petals at anthesis are spreading over 50° to patent or even somewhat reflexed. This is a group of 11 species: the nomenclatural type Grias cauliflora Linnaeus (1759: 1075) , G. fendleri Seemann (1854: 126) , G. neuberthii J.F. Macbride , G. peruviana Miers , G. colombiana Cuatrecasas (1951: 96) , G. multinervia Cuatrecasas , G. haugthii R. Knuth (1939: 31) , G. longirachis , G. ecuadorica , G. subbullata , and G. angustipetala . The second group is characterized by flowers with the filaments of outer stamens fused 50 to 80 % of their length, exhibiting a conspicuously developed, fleshy, bowl-shaped staminal tube, and anthers ± oblong, with expanded, cucullate connectives with lateral flaps that enclose most of the thecae. The petals at anthesis are erect, sometimes reflexed inwards at apex to 50° spreading. This is a small group of three species, that includes: G. theobromicarpa , G. purpuripetala , and the new species G. portillae . For morphological differences among these three closely related species, see Table 1 .

Grias portillae can be distinguished from all other species in the genus, and is here recognized as a new taxon due to the presence of the following highly distinctive vegetative and reproductive characters: leaf blades with shortly caudate apex, flowers with the consistent combination of dark purple petals and creamish-white androecium, and mainly the presence of 18–21 stamens, the smallest number of stamens in the genus, with filaments inserted in only one level on top of rim, which is a unique feature in Grias , as the remaining species have filaments inserted in two to four levels.

The androecium of Grias portillae externally may look similar to that of G. theobromicarpa ; however, dissection of flowers reveals strong morphoanatomical differences between these two species, as the aforementioned fewer number of stamens (18–21 vs. 34–40), filaments inserted in only one level on top of rim (vs. filaments inserted in two levels, one level on rim, another level just below rim). Furthermore, the white to light yellow flowers of G. theobromicarpa was observed in all three known populations of this species (including the type, collected by the author and additional field images sent by Thomas Couvreur and from Los Cedros Biological Reserve; fig. 1).

Among the species of Grias , G. purpuripetala is the only taxon with red-purple flowers in a genus previously known by having predominantly white to yellow flowers, sometimes tinged red ( G. neuberthii ). Although Grias portillae is a second species with purple petals, the latter cannot be confused with G. purpuripetala because of the consistent combination of dark-purple petals and creamish-white androecium, which is unique among species of Grias , while in G. purpuripetala the petals are red-purple and the androecium is rose to pink.

Regarding the presence of colleters along the blades margin that were observed in Grias portillae , this inconspicuous feature has also been observed in herbarium material from all other species in the genus, with the exception of G. multiflora , due to limited access to herbarium specimens, and also in cultivated fresh material (from Cornejo & Fernandez 6783, GUAY, NY; Mori et al. 2023). Therefore, leaf blades with marginal colleters are here reported as an overlooked vegetative character at generic rank in Grias . Young blades with marginal colleters have been also observed by the author in several species of Gustavia Linnaeus (1775: 12) , such as G. angustifolia Benth. (1845: 99) , G. occidentalis Cuatrecasas (1951: 94) , and G. pubescens Tafalla ex O. Berg (1856: 443 , Cornejo 2018), and in two of the three valid species of Couroupita Aubl. (1775: 708) : C. guianensis Aubl. (1775: 708) and C. nicaraguarensis DC. (1828: 294) . Those rather inconspicuous blades margin colleters are minute, white, and secreting tiny microdroplets while functional in very young leaves, soon turning obsolete as persistent dark brown spaced marginal dots that can be observed in mature leaves under magnifying glass (10x); further field observations in remaining species of Couroupita and Gustavia may reveal that foliar marginal colleters might be also a trait at generic rank in the later genera. Leaf blade colleters reported in Cariniana estrellensis (Raddi) Kuntze (1898: 89) were suggested to provide young leaf protection ( Souza Paiva 2012), so it is likely that a similar role could be played by the colleters from Grias and in the remaining species and genera of Lecythidaceae were they are found.

Etymology: —The epithet honors José Portilla, who discovered the only population known, collected the type and made available to the author the specimens and field images of the new species.

Habitat and distribution: — Grias portillae is an understory low tree that inhabits the interior of evergreen lower montane Andean slopes in wet forest at 1200 m. It is known only by the type locality in Río Cristal, at environs of Lita, province of Imbabura, northwestern Ecuador. Similar to G. theobromicarpa , another closely related species that is also endemic to evergreen montane Andean slopes in northwestern Ecuador, that was described based solely on the type, and from which two additional populations were discovered 10 years after the original publication, it is expected that further field exploration would yield the discovery of additional populations of Grias portillae in northwestern Ecuador.

Phenology: —Flowering was observed in early July; fruiting material has not been collected yet.

Conservation status: —This species is uncommon in Río Cristal, Lita, where less than 10 small trees have been found persisting in secondary habitats. Based on the very small area of occurrence (10 km 2), an extent of occurrence of 10.3 km 2, and its persistence in only one locality (fig. 1) that is under pressure by steady deforestation, forest fragmentation and conversion to pastures for livestock in northwestern Ecuador, G. portillae is here assigned a provisional category of Endangered (EN B2a(iv)), following the IUCN (2022) criteria.

Figures

FIGURE 1. Distribution map of Grias portillae Cornejo (*) and G. theobromicarpa Cornejo & S.A. Mori (+).

FIGURE 2. Grias portillae Cornejo. A, Crown, a shortly caudate apex of leaf blade at upper right corner. B, Oblanceolate leaf blade held by the author and his daughter. C, Cauline inflorescence, adaxial view of stigma at upper right corner. D, Two inflorescences with persistent calyces after shed corollas. E, Flowers at anthesis. F, Longitudinal section of androecium exhibiting stamens with filaments inserted in one level on top of rim. Photos A, C, E, by José Portilla; D, F by Xavier Cornejo; B, by Dana Loor, from the type collection.