Themistoclesia diminuta Pedraza, 2022

Abstract, Paola Pedraza-Peñalosa, 2022, Themistoclesia diminuta (Ericaceae: Vaccinieae), a new mortiño and blueberry relative from Colombia, Phytotaxa 556 (3), pp. 291-295 : 292-293

Themistoclesia diminuta Pedraza , sp. nov. ( Fig. 1 )

Type: — COLOMBIA. Cauca: Parque Nacional Natural Munchique, kms 42–47 NE of Uribe , 2350–2560 m, 24 April 1979 (fl), J. L. Luteyn, M. León-Luteyn, & G. Morales et al. 7408 (holotype: NY! [02636308]; isotype: COL!) .

Diagnosis: — Themistoclesia diminuta differs from all other Themistoclesia in its combination of subsessile flowers, pedicels articulate with calyces, calyces with lobes reduced to an inconspicuous apicule, corollas that are pale green with purple lobes, urceolate, and 3.5–4 mm long, and purple berries that are hemispherical and 5-angled.

Epiphytic or terrestrial shrubs with pendant branches or terrestrial shrubs, ca. 40 cm tall and scrambling over other vegetation; mature stems terete, bark brown, smooth, glabrescent, hairs simple, unicellular, eglandular; twigs subterete, smooth, puberulous, hairs simple, wavy, unicellular, eglandular.Axillary buds compressed; prophylls 2, inconspicuous, opposite, valvate, ovate, 0.6–1 mm long, apex acute, margin inconspicuously ciliolate, abaxially glabrous. Leaves alternate; petiole subterete, 1–2 mm long, puberulous, hairs simple, unicellular, eglandular; lamina coriaceous, ovate or elliptic, 1.2–2.7 × 0.7–1.5 cm, base obtuse or rounded, margin entire, eciliate and drying slightly concave basally, apex acute or subacute, very rarely acuminate, terminating in a short and rigid mucro, adaxially inconspicuously glabrate, hairs simple, multicellular, glandular, mixed with a few unicellular and eglandular, abaxially inconspicuously glabrate, hairs caducous, multicellular, glandular, laminar glands one or two pairs, basal, venation completely obscured abaxially, only midrib impressed adaxially. Flowers axillary, solitary, tucked underneath the leaves, subsessile, 5- merous, actinomorphic, obdiplostemonous; bracts inconspicuous, persistent, ca. 7, chartaceous, ovate, 0.5–0.7 × 0.3–0.4 mm long, margin ciliolate with caducous hairs, apex acute or obtuse, glabrous on both sides, venation obscure. Pedicels practically absent, ca. 0.8 mm long, articulate with calyx. Calyx green, obconic, 5-angled, angles alternating with lobes, 2–2.5 mm long, puberulous especially over the angles, hairs simple, unicellular, eglandular; calyx tube obconic, 1.5–1.9 mm long; limb erect, 0.3–1 mm long; lobes reduced to inconspicuous apicules, 0.1–0.4 mm long, margin entire, eglandular, ciliolate, hairs simple, unicellular, eglandular, sinuses flat. Corolla light green with purple lobes, urceolate and strongly constricted at throat, terete, 3.5–4 × 2.5–3 mm, 1–1.5 mm wide at throat, apically puberulous, hairs simple, unicellular, eglandular, glabrous inside; lobes with valvate aestivation, reflexed at maturity, deltoid, 0.5–0.6 × 0.3–0.5 mm, apex acute. Stamens 10, equal, exserted, 4–5 mm long; filaments distinct, linear, not geniculate, ca. 1.8 mm long, glabrous; anthers ca. 3.5 mm long, connective not expanded, spurs absent; thecae 1.5 mm long, oblong, without basal appendage, inconspicuously papillate; tubules 2, distinct, straight, ca. 2 mm long, smooth, dehiscing by introrse apical slits, 0.2–0.5 mm long. Style included, ca. 3.5 mm long; stigma punctiform. Nectary disk pulvinate, glabrous or puberulous, hairs simple, unicellular, eglandular. Berry white when immature, purple at maturity, hemispherical with apex flat when fresh and slightly concave when dried, slightly 5-angled, ca. 4.6 mm diam., puberulous especially over angles, hairs simple, unicellular, eglandular; seed with mucilaginous coat.

Specimens examined: — COLOMBIA. Cauca: Parque Nacional Natural Munchique , 1–2 km into the park beyond the entrance, ca. 2°40’N, 76°50’W, 2100–2440 m, 7 May 1984 (fl), J. L . Luteyn et al. 10234 ( COL); Municipio El Tambo, Vereda La Romalia , camino entre la cabaña de parques y el observatorio, 2°38’46.9”N, 76°55’25.3’’W, 2500 m, 8 August 2004 (fl, fr), P . Pedraza & C. Giraldo 1180 ( NY, COL). Chocó: Carretera Ansermonuevo–San José del Palmar , límite con el Valle del Cauca, Alto del Galápago , 2100 m, 27 August 1976 (fr), E . Forero et al. 2192 ( COL, MO, NY), 2193 ( COL); ca. 51–53 km W of Ansermonuevo, ca. 4°40’N, 76°26’W, 1925–2000 m, 13 May 1984 (fl, fr), J. L . Luteyn et al. 10435 ( NY); from Chocó-Valle del Cauca border W 10 km towards San José del Palmar , 1524–2050 m, 15 May 1984 (fl, fr), J. L . Luteyn et al. 10512 ( NY). Municipio San José del Palmar, Vereda Río Blanco , Serranía de los Paraguas, en la carretera que conduce de El Cairo a Río Blanco , 4°44’25.6”N, 76°17’50.7’’W, 2150 m, 23 July 2004 (fl, fr), P . Pedraza & C. Pedraza 1131 ( COL, NY). Municipio San José del Palmar, Cerro del Torrá , arriba del helipuerto, 1920 m, 8 January 1984 (fl, fr), F. A . Silverstone-Sopkin et al. 1647 ( COL, MO x2, NY); 1920–1950 m, 11 August 1988 (fl, fr), F. A . Silverstone-Sopkin et al. 4302 ( NY) . Valle del Cauca: Municipio El Cairo, Corregimiento El Boquerón, Vereda Las Amarillas, Serranía de Los Paraguas, along the road to and beyond Cerro del Inglés , 17–23 km W of El Cairo, ca. 4°45’N, 76°20’W, 1750–2050 m, 13 May 1988 (fl), J. L . Luteyn et al. 12295 ( NY); 21–25 km beyond El Cairo , ca. 4°45’N, 76°20’W, 1850–2000 m, 25 April 1989 (fl, fr), J. L . Luteyn & J . Giraldo 12646 ( NY) .

Distribution, habitat, and phenology: — Themistoclesia diminuta has been collected in pluvial montane forests at the edges of primary vegetation or in secondary forests between 1524 to 2500 m elevation. It is only known from the Colombian Western Cordillera in regions that remain poorly known relative to their plant richness. The geographic distribution of Themistoclesia diminuta is likely much larger than that inferred from the known herbarium collections. Fertile individuals are extremely hard to detect in the field, even for the trained eye, as these inconspicuous shrubs have sessile flowers with corollas that are less than 5 mm long, light green in color and fall off easily. It flowers and fruits in January, April, May, July and August.

Etymology: —The species epithet refers to the unusually small flowers.

Discussion: — Themistoclesia diminuta most closely resembles T. smithiana ( Standley 1938: 883) Sleumer (1941: 390) in their distichous leaves of similar dimensions and their small flowers that can also be sometimes pale green in T. smithiana . Moreover, the new species is Andean whereas T. smithiana is restricted to several montane areas in Costa Rica and Panama. The two species can be easily separated by characters listed in Table 1 .

The overall habit and vegetative appearance of Themistoclesia diminuta can superficially resemble T. cuatrecasasii Smith (1950: 29) , a frequent species in the cloud forests of Central and South America that co-occurs with T. diminuta (see Luteyn & Pedraza 2013 for notes on the most recent synonyms for T. cuatrecasasii ). Themistoclesia cuatrecasasii has longer (ca. ≥ 5 mm) tubular corollas that are red, pink or white (vs. 3.5–4 mm long, urceolate, and pale green with purple lobes in T. diminuta ), continuous pedicels (vs. articulate), and spherical berries that are crowned by the persistent calyx limb (vs. hemispherical and flat at the apex, 5-angled, with an inconspicuous calyx limb). These two species might hybridize, as suggested by the morphology of the collections J. Luteyn & J. Giraldo 12649 (NY) and J. Luteyn & J. Giraldo 12647 (NY), both of which have small and tubular corollas that are white or translucent with rose lobes. However, if the nearly 45 years between the first known herbarium collections made of the new species and this publication serve to exemplify the sparse documentation of Themistoclesia and of the Ericaceae of western Colombia, it would not be surprising if more undescribed species of this group were discovered from this region. Evidence of the unusual concentration of new Ericaceae in western Colombia has been recently recorded in other Vaccinieae (see Pedraza-Peñalosa 2008, 2015a, 2015b).

Figures

FIGURE 1. Themistoclesia diminuta. A. Branch. B. Branch apex with a calyx (proximal), an axillary flower (distal), and detail of leaf margin. C. Close-up of flower (left) and corolla (right). D. Calyx with nectary disk exposed. E. Stamens in adaxial (left), abaxial (center), and lateral (right) views. F. Branch with immature fruits and flower. G. Fruit. H. Axillary bud. (A–E drawn from Luteyn 12295; F–G drawn from Luteyn 7408; H drawn from Pedraza 1131.)