Thismia andicola Aguilar-Cano, S. Guzman-Guzman & Lopera-Toro, 2023

Aguilar-Cano, José, Guzmán-Guzmán, Santiago & Lopera-Toro, Alejandro, 2023, Thismia andicola sp. nov. (Thismiaceae): a new species from the northern Andes in Colombia, Phytotaxa 579 (2), pp. 107-116 : 109-111

Thismia andicola Aguilar-Cano, S. Guzman-Guzman & Lopera-Toro , sp. nov. ( Figures 1 , 3 )

Diagnosis:— Thismia andicola sp. nov. is unique in sect. Ophiomeris in its combination of the following features: outer surface of the floral tube light blue and densely punctate with sky-blue metallic dots, inner tepals 4.6–5 mm long and stigma obovoid, covered adaxially by regularly distributed simple uniseriate multicellular trichomes.

Type:— COLOMBIA. Norte de Santander: municipio de Toledo, vereda San Alberto, Cuenca del Río Talco, Zona Amortiguadora del Parque Nacional Natural Tamá , 7°13’40.98”N, 72°18’42.22”O, 2030 m, 17 April 2019 (fl.), Alejandro Lopera-Toro, s.n. (holotype: COL-615794!, in alcohol) .

Terrestrial achlorophyllous herbs, 8–15 cm high. Tuber ovoid, 11.6 × 4.9 mm, whitish to yellowish; roots filiform, up to 50 mm long, sometimes with a small tuber at the top. Stem erect, 3.7–10.6 × 1.9–2.0 cm, longitudinally bisulcate, whitish. Leaves bract-like, 4, crowded at apex of stem with internode ca. 1 mm long, decussate, surrounding the base of ovary in the form of an involucre, navicular, ovate-lanceolate, 4–4.5 × 1.7–1.8 mm, whitish, apex obtuse. Flower terminal, solitary. Floral tube zygomorphic with respect to perianth, urceolate, 7 × 9.1–10.2 mm; outer surface light blue, densely punctate with sky-blue metallic dots and sulcate with 12 dark blue longitudinal depressions; inner surface papillose, with ribs and sparse simple unicellular trichomes 0.7 mm long. Tepals 6, heteromorphic, inserted more or less at the same level in the distal portion of the floral tube, inflexed in flower bud and erect in pre-anthesis; outer tepals, 4.6–5 × 3 mm, ovate, yellow-greenish, apex obtuse, margin entire, venation finely hyphodromous; inner tepals with laminar portion lanceolate, 5 × 2.2 mm, yellow-greenish, gradually tapering into a filiform portion; filiform portion 25.3–30.6 mm long, cloudy, whitish light blue, twisted in pre-anthesis, apex slightly rounded. Annulus extending horizontally from the bases of tepals to form a circular orifice ca. 2.5 mm in diam., consisting of 3 green segments arranged in the radii of longer tepals; each segment 4.4 × 2.9 mm, ornamented with three finely raised ridges on the upper side, running parallel to the orifice, outermost ridge 0.5 mm wide, middle and inner ridges 0.5 mm wide, separated by 0.3 mm between them. Stamens 6, arranged in the radii of tepals, free, stamen filament bases expand laterally and fuse into a ring, ca. 0.9 mm wide beneath the point of tepal insertion with stamens hanging from it; filament 1.0–2.0 × 0.6–0.9 mm, glabrous; connective 1.8 × 1.5 mm (including apical lobes); lateral lobes 2, linearlanceolate, 1.3 × 0.2 mm, divaricating; apical lobes 2, ovate, 0.7 × 0.3 mm, apex rounded; united thecae, arranged subterminally on the connective (just below the apical lobes), ovoid, 0.8 × 0.8 mm, glabrous; interstaminal lobes inserted at the margin of ring formed by the expanded bases of the stamen filaments, 6, alternating with the tepals, free, triangular-elliptic, 0.9–1.6 × 0.9 mm. Ovary inferior, broadly obconical, 2.4 × 2.6 mm, unilocular, with parietal placentation; placentas inserted in the basal part of the locule, 3, in the form of longitudinal lines, bearing numerous ovules; style erect, cylindrical, 1.8 × 0.5 mm; stigma divaricate, trilobed, obovoid, 1.7 × 1.1 mm, covered adaxially by regularly distributed simple uniseriate multicellular trichomes 0.03–0.11 mm long. Fruit not seen.

Etymology: —The specific epithet refers to the distribution of the species in the South American Andes cordillera.

Phenology: —The only known population of the new species was recorded at the beginning of flowering period in late April, coinciding with the rainy season in the region ( Guzman & Ruiz 2012).

Distribution and ecology: —A single population of Thismia andicola is known in the northern Cordillera Oriental of the Andean Region of Colombia ( Fig. 2 ), at an elevation of 2030 m a.s.l., where two individuals were observed. The vegetation in the type locality is classified as sub-Andean Forest ( Cuatrecasas 1958). The two individuals were found in bare soil on a recently cleared trail, where the thick layer of leaf litter (approximately 15 cm deep) had been removed after four days of using the trail.

Conservation status: —The new species is known from the buffer conservation zone proposed by the Tamá National Natural Park (PNN 2018), where two individuals were found in a single locality. Although the species is found in a protected area, albeit near the edge, its range could still be affected by human pressures, mainly by agriculture, livestock grazing and logging, as well as climate change. Population density could not be assessed due to the small number of individuals encountered. It is suspected that the population is in decline as a result of high levels of environmental threat. Research is urgently needed to identify other possible localities of Thismia andicola and establish the current size of population(s) and its dynamics. Present knowledge of the population status is insufficient to establish a conservation status, therefore, according to the IUCN (2019) we categorize T. andicola as Data Deficient (DD).

Figures

FIGURE 1. Thismia andicola. A. habit. B. top view of flower. C. Longitudinally dissected view flower. D. abaxial surface of stigma lobe covered by regularly distributed simple uniseriate multicellular trichomes. E. Inner surface of floral tube with rib sparsely covered with simple unicellular trichomes. F. Papillose inner surface of floral tube. G. Distal portion of floral tube showing tepal bases, annulus, and androecium. H. Stamen and interstaminal lobe, adaxial view. J. lateral view of ovary, style and stigmas. K. cross section of unilocular ovary showing parietal placentas. By Lisa Anzellini.

FIGURE 2. Map showing distribution of species of Thismia sect. Ophiomeris.

FIGURE 3. Thismia andicola. A. habit. B. proximal bract (left), distal bract (right). C. lower side annulus showing stamen filament bases expand laterally and fuse into a ring with interstaminal lobe and stamens hanging from its margin (white arrow indicates thecae). D. top view of annulus segment showing outermost ridge (black star), innermost ridge (white star) and middle ridge between them. E. Interstaminal lobe showing apical papillose portion (All of the holotype). Picture by José Aguilar-Cano.