Tecunumania stothertiae Cornejo & H. Schaefer, 2020

Cornejo, Xavier, Schaefer, Hanno & Nee, Michael H., 2020, Tecunumania stothertiae (Cucurbitaceae): a new species from western Ecuador and a new generic record for South America, Phytotaxa 446 (3), pp. 199-204 : 200-203

Tecunumania stothertiae Cornejo & H. Schaefer , sp. nov. ( Fig. 1 ).

Tecunumania stothertiae is a new species from western Ecuador that resembles the Mesoamerican T. quetzalteca Standl. & Steyerm. , but differs by the staminate flowers with apices of petals rounded to broadly obtuse (versus shortly mucronate to cuspidate and abruptly acuminate), the fruits pyriform to subelliptic (versus globose to subglobose), and seeds glabrous (versus appressed-pilose).

Type: — ECUADOR. Chimborazo: Cumandá , 4 km E, secondary wet forest, 2°12’ S 79°07’ W, 400 m, 8 February 2018 (fl, fr), X. Cornejo 9182 (Holotype: GUAY!; Isotype: NY!) .

Vine, herbaceous, to 20 m long with persistent rootstock. Terminal branches with stems subcylindrical, ribbed, turning tetragonal, 3–4 mm diam., pulverulent to glabrous. Stipular white trichomes present, the hairs pluricelular, uniseriate, hyaline. Leaves alternate; lamina membranaceous, ovate, 13–18 × 15–20 cm, (5–)7-lobed, 5-nerved from base, the base broadly cordate, the apex acuminate, the margins denticulate, the lamina minutely scabridulous and somewhat glabrescent on both sides, the trichomes erect, pluricelular, hard, thickened at base, supported by up to 20 flattened, white to hyaline glossy cells; petioles 8–12 cm long, with a tuft of pluricelular, uniseriate, white hairs present at the apex; tendrils 2–5-fid. Flowers solitary, axillary. Staminate flowers with pedicels 1–1.5 cm long. Hypanthia turbinate, ca. 1.5 × 0.9 cm (at broadest apex), glabrous. Calyx broadly divergent at anthesis, the sepals 5, green, ligulate, coriaceous, 1.5–1.7 × 0.25–0.3 cm, free to base, spaced ca. 4 mm apart from each other, costate abaxially, the apex apiculate, the apiculum ca. 1.5 mm long, the margins pilose. Corolla broadly campanulate, the petals erect, obovate, membranaceous, ca. 2.3 × 1.3 cm, longitudinally 3-costate abaxially, fused at base, rounded to broadly obtuse and mucronulate at apex, yellow, glabrous to pilose. Stamens 3, inserted at base of tube, the filaments ca. 6 mm, stout, fused into a thick column with sharp edges, broader and buttressed at base, white, glabrous. Anthers connate forming a mass ca. 1 × 0.75 cm, yellow. Pistillate flower unknown. Fruit a septate berry with a thin cuticular rind, pyriform to subelliptic, 7 – 9 × 5 – 6 cm, smooth, glossy, at maturity green to yellowish-green, glabrous. Seeds ± elliptic, 7 – 8 × 4 – 5 mm, laterally convex, obtuse at base, bearing a lateral-subasal funicular scar, a marginal rim absent, evenly dark-brown, glabrous.

Etymology: —The epithet honors Karen Stothert, as a recognition for her unsurpassed research on archaeology of Las Vegas, a preceramic culture in which the early use of Cucurbitaceae has been documented and that dates back to the beginning of the Holocene in coastal Ecuador (10.800 – 6.600 years BP) ( Stothert, 2011).

Habitat and distribution: — Tecunumania stothertiae is currently known only from three localities at the foothills on the western Andean slopes of Ecuador. The type locality, where only 5 individuals were observed, is a streamside of a secondary wet forest located 4 km E of Cumandá in the westernmost part of Chimborazo province in central-western Ecuador. The remaining two collections were gathered within a total range of 110 km in similar secondary wet forest ecosystems. Tecunumania was previously thought to be endemic to Mesoamerica growing in southern Mexico (Chiapas) and adjacent Guatemala, from where the type was collected, and disjunct in Costa Rica. Therefore, the discovery of Tecunumania stothertiae represents a new generic record for Ecuador and for South America, and the new southernmost limit for the genus.

Germination: —The seeds of Tecunumania stothertiae can take one to four weeks to germinate and have ca. 80 % of viability (X.C., unpubl. data).

Conservation status: —At present, the native vegetation of the area where Tecunumania stothertiae occurs is disturbed by selective timber tree cutting, deforestation and forest fragmentation due to the advancement of the agricultural frontier, including cattle farming. Therefore, the preliminary status of Endangered (EN B1ab[iii]) ( IUCN, 2012) is assigned to this species.

Figures

FIGURE 1. Tecunumania stothertiae Cornejo & H. Schaefer. A, Staminate flower, lateral view; B, Staminate flower, frontal view; C, Staminate flower bud; D, Leaf blade, abaxial view; E, Sectioned fruit with foam indicating the presence of saponins; F, Mature seeds. Photographs taken from the holotype, Cornejo 9182 (GUAY).