Zamia oligodonta Calderón-Sáenz & Stevenson (2003: 486)

Calonje, Michael, Morales, Gustavo, López-Gallego, Cristina & Roldán, Francisco Javier, 2015, A taxonomic revision of Zamia montana and Zamia oligodonta, with notes on their conservation status, Phytotaxa 192 (4), pp. 279-289 : 285-288

Zamia oligodonta Calderón-Sáenz & Stevenson (2003: 486) . Figs. 4 , 5 .

Type:— Colombia, cultivated by E. Calderón Sáenz, originally collected in Risaralda, Calderón-Sáenz 174 (holotype FMB!).

Literature:— Calderón-Sáenz & Stevenson (2003), Lindstrom (2009, as synonym of Z. montana ).

Illustrations / figures:— Calderón-Sáenz & Stevenson (2003), Galeano et al. (2005).

Etymology:— The specific epithet is derived from the greek roots oligo (few) and odonto (=teeth), in allusion to the presence of a few teeth in the apical region of each leaflet.

Description:— Stem s typically subterranean, rarely arborescent, to 40 × 11 cm, erect or decumbent, typically solitary but occasionally branched. Cataphylls chartaceous, narrowly triangular, grey-tomentose with glabrous dark brown margin, to 7 cm long, and 2.5 cm wide at base. Leaves pinnately compound, 1–3 per stem apex, held straight to slightly arching, to 290 cm long. Petiole to 162 cm long, sparsely armed with prickles to 4 mm long, base swollen and glabrous, to 6 cm wide. Rachis to 131 cm, unarmed or sparsely armed with prickles in the proximal third, carrying 2 to 26 opposite to suboppositely arranged leaflets. Leaflets narrowly elliptic to elliptic, straight to very slightly falcate, cuneate basally, acuminate to caudate apically, chartaceous to subcoriaceous, more or less flat and appearing undulate, veins forming grooves on adaxial surface, strongly protruding on abaxial surface, margins revolute on proximal third, transitioning to straight on distal half, entire but often uneven and slightly sinuous at the distal end and appearing as if broadly toothed. Middle leaflets 20–50 cm × 6.6–14 cm, spaced 8–14 cm apart and sometimes slightly imbricate, apical leaflets 26.5–39 × 10.4–12.4 cm, basal leaflets 35.5–47.5 × 8.0– 12 cm. New leaf flushes carry leaflets that are white tomentose at first, quickly becoming glabrous and light yellow-green in color, maturing acropetally to a bronze color before turning a glossy bright green at maturity. Eophylls carrying 2 narrowly elliptic leaflets 20.0–23.7 × 6.7–8.4 cm, petioles 40–50 cm long, rachis 0.4–0.5 cm long. Pollen strobili 1–3 per stem apex, to 7–11 × 2.0– 2.7 cm, emerging yellow-green tomentose, maturing to yellow-beige tomentose, narrowly ovoid-cylindrical, apex obtuse to acute, peduncle to 3.6 × 1.4 cm, similar in color to rest of strobilus. Microsporophylls arranged in 16–20 orthostichies of 18–28 fertile sporophylls each, 5.0–5.2 × 3.0– 3.2 mm, sterile apex encompassing 1/3 of total length of sporophyll, microsporangia 8–13, 0.7–1.0 mm, limited to the abaxial surface and arranged in two separate groups arranged along sporophyll margin. Ovulate strobili 1 per stem apex, erect, ellipsoid, emerging reddish-brown tomentose and transitioning to brown and light tan at maturity, to 17 × 11 cm, sterile apices obtuse or pungent, 1–2 cm long, peduncles obscured by cataphylls 2–3 × 2–3 cm. similar in color to sporophylls. Megasporophylls arranged in 6–7 orthostichies of 3–5 sporophylls each, bullae truncate with hexagonal to oblong-hexagonal distal face 2.5–3.5 × 5.0–6.0 cm and 7–10 mm thick, terminal facet broad, slightly protruding, and indented. Seeds ovoid-pyramidal, 3.5–4.2 × 2.2–2.8 cm, sarcotesta ripening from pink to orange, 10–20 mm thick.

Distinguishing features:— Although the specific epithet of the species refers to the presence of a few teeth in the apical region of each leaflet, the leaflet margins of this species can be considered mostly entire but in some cases are unevenly sinous (repand) at the distal end. This unevenness in some cases (such as in the holotype) is strongly marked, giving the leaflets the appearance of having broad teeth at the distal end. However, the irregularity of the distal margin is quite variable, with some margins being completely entire and others only slightly sinuous. Moreover, the margins cannot be considered truly serrate such as in the case of Z. disodon , Z. urep , and species of the Z. skinneri Dietrich (1851: 146) species complex in which every individual vein terminates in a distinct tooth. The repand distal margins are not a consistent character in Z. oligodonta and are also present in some leaflets of Z. montana so they cannot be considered a good diagnostic character.

Zamia oligodonta is readily distinguished by its broad narrowly elliptic to elliptic leaflets which are prominently-veined, undulate, and with long acuminate to caudate tips, its (mostly) subterranean stem carrying few (up to 3) leaves, and sparse prickles on its petioles.

Distribution and habitat:— Zamia oligodonta is endemic to the department of Risaralda, where it occurs in premontane rain forests (sensu Holdridge 1967) on the Western Cordillera at elevations between 1500 to 1800 m. Rainfall averages 2600–2700 mm per year and is bimodal, with rainfall peaks occurring in October–November and April–May, and the driest months being January–March and July–August. The mean annual temperature is 18.8 ° C, with temperature ranging from 13.6° to 24.3° C (climate data derived from GIS analysis using Worldclim 1.4 [release 3] climate layers as described by Hijmans et al. 2005).

Reproductive phenology:— Very little is known about the reproductive phenology of this species. New and developing ovulate strobili as well as new and juvenile pollen strobili were observed in late March of 2014, mature seeds have been reported in October. All previously observed pollen strobili were completely rotten by early July, and based on their stage of development observed in March, pollen release likely occurred between April and May.

Ecology:— No herbivory or pollinators have been observed on this species.

Conservation status:— Zamia oligodonta is known from only five subpopulations with an estimated total 1,000 adult plants total within a total extent of occurrence of 30 km 2. The area of occupancy for the species, calculated by adding the areas with the known altitudinal range for the species within its extent of occurrence, is estimated to be 5 km 2.

In all five populations recruitment appears to be healthy, with plants of different ages observed. Fertile seed strobili at different stages of maturity have been observed in two populations, indicating that reproduction is occurring normally. One of the populations is within a protected area in Risaralda.

The region where Z. oligodonta is native appears to still have a considerable amount of forest cover left. As the species was recently described (Calderón–Sáenz & Stevenson 2003), little is known about its population demographic dynamics, although deforested areas of otherwise suitable habitat suggest that the species is declining. The main threat to this species appears to be habitat destruction for the creation of cattle pastures as well as agricultural production, primarily of coffee and sugar cane.

The species was previously classified as Data Deficient in the Red List of Colombian cycads ( Galeano et al. 2005), but we now have enough field data to recommend its classification as Endangered based on IUCN Criteria B1ab(i–v)+2ab(i–v); C1. Specific locality information has been purposefully withheld from this paper to minimize the risk of illegal harvesting of this threatened species.

Historical notes:— The original description for Z. oligodonta was based on a few plants cultivated by Eduardo Calderón Sáenz. In situ observations carried out during this study confirmed that wild plants attained much larger dimensions than the cultivated plants upon which the original description was based.

Additional specimens examined:— COLOMBIA. Cultivated by E. Calderón Sáenz, originally collected in Risaralda, Calderón Sáenz 175 (JAUM!), 182 (COL!), 183 (FMB!, NY!). Live plants cultivated by E. Calderón Sáenz also studied. Risaralda: 1750–1800 m, 9 July 2014, Roldán et al. 4276 (HUA!).

Figures

FIGURE 4. Zamia oligodonta in habitat in Risaralda, Colombia. A. Eophyll leaflets. B. Leaf of juvenile plant. C. Petiole base showing sparse prickles. D. Slightly arborescent ovulate plant with 30 cm. ruler for scale. E. Adult sized plant with completely subterranean stem and two leaves, each approximately 2.7 m long. F. Middle leaflet from adult plant.

FIGURE 5. Zamia oligodonta in habitat in Risaralda, Colombia.A–C. New leaves at different sequential stages of development. D–G. Ovulate strobili at sequential stages of development. H–I. Juvenile pollen strobili approximately 1 month away from pollen dehiscience.