Wednesday, January 2, 2019

[Botany • 2018] Zamia paucifoliolata (Zamiaceae, Cycadales) • A New Species of Zamia from Valle del Cauca, Colombia

Zamia paucifoliolata Calonje

in Calonje, López-Gallego &Castro. 2018. 

Zamia paucifoliolata, a new cycad species from the Pacific lowlands of Valle del Cauca, Colombia, is described and illustrated. It is distinguished from other species of Zamia by having an underground stem typically bearing large solitary leaves with eighteen or fewer leaflets, villous strobilar axes, microsporangia borne on both the abaxial and adaxial side of microsporophylls, and seeds that are longer than 18 mm. It is compared to Z. pyrophylla, Z. cunaria, and Z. ipetiensis, species which it most closely resembles.

Keywords: Chocó biogeographic region, systematics, taxonomy, Gymnosperms

FIGURE 1. Vegetative characteristics of Zamia paucifoliolata.
 A. Seedling with eophyll, top and side view. B. Center of petiole showing prickles. C. Adult plant with immature seed strobilus. D. New leaf flush. E. Cataphylls. F. Middle leaflet of adult plant.

FIGURE 2. Reproductive characteristics of Zamia paucifoliolata.
A. Microsporophyll, adaxial side. B. Microsporophyll, abaxial side. C. Cross section of pollen strobilus, adaxial side. D. Closeup of pollen strobilus near pollen release stage. E. Pollen strobilus with peduncle near pollen release stage. F. Immature seed strobilus. G. Megasporophyll with immature seeds, adaxial side. H. Megasporophyll with immature seeds, abaxial side. I. Megasporophyll face, immature. J. Megasporophyll face, mature. K. Seed with ripe sarcotesta. L. Seed sclerotesta.
A–I based on collection López-Gallego et al. 68–69 (HUA), J–K based on Castro et al. 1118–1119 (HUA), L based on Castro et al. 1289 (holotype HUA; isotypes COL, CUVC, FMB, JAUM, MEDEL, TOLI).

Zamia paucifoliolata Calonje sp. nov.

 Diagnosis:— Zamia paucifoliolata most closely resembles Z. pyrophylla from which it is distinguished by the light green leaf flushes, the leaflets that are broader and less numerous, the fewer and larger mature megasporophylls and seeds, and the lighter colored pollen strobili.

FIGURE 3.  Zamia paucifoliolata in its natural habitat at the type locality.
 A. Middle leaflets collected from plants at different stages of development. B. Juvenile plant. C. Adult plant with seed strobilus, showing yellow clay soils in which the species grows. D. Adult plant in habitat with Jonatan Castro (left) and Michael Calonje (right). E. The largest leaf yet observed for this species, measuring 285 cm long and carrying 18 leaflets.

 Etymology:— The specific epithet refers to the small numbers of maximum leaflets produced by leaves of this species which are among the least numerous of any species of Zamia. Leaves on adult plants carry between 10 and 18 leaflets (n=135 leaves, mode=10, mean 11.6), and only a few species with broad, prominently-veined leaflets carry the same number or fewer leaflets. Namely, Z. wallisii Braun (1875: 376), with the broadest leaflets in the genus, has leaves with a maximum of 11 leaflets, Z. dressleri Stevenson (1993: 6) carries up to 14 leaflets, and Z. imperialis Taylor et al. (2008: 421) similarly carries a maximum of 18 leaflets. The small number of leaflets carried by leaves of Z. paucifoliolata readily distinguishes it from its putative relatives Z. cunaria, Z. ipetiensis, and Z. pyrophylla, all of which carry a maximum of 32 leaflets.

Ecology:— The known populations of the species appear to be viable, with a larger proportion of juveniles compared to adults, i.e. evidence of reproduction and regeneration. Plants are distributed in highly dense patches on the understory of the forest, on moderately steep slopes and near small streams. Little is known about leaf phenology, frequency or rate of strobilus production or germination time. Mature seed strobili with ripe seeds have been observed in February and May, whereas pollen strobili have only been observed in late August. Immature seed strobili have been observed in June, August, and September. There is no information yet about microrganisms associated to roots or species interactions involved in pollination or seed dispersal, but a good proportion of viable seeds has been observed in female strobili. The typical herbivores associated to Zamia species, Eumaeus Hübner (1819: 67), have not been observed yet either, but there were signs of herbivory by leaf miners. A permanent plot has been established in one of the populations to monitor population dynamics and other ecological aspects of the species.



 Michael Calonje, Cristina López-Gallego and Jonatan Castro. 2018. Zamia paucifoliolata, A New Species of Zamia (Zamiaceae, Cycadales) from Valle del Cauca, Colombia. Phytotaxa. 385(2); 85–93. DOI:  10.11646/phytotaxa.385.2.4

Resumen: Se describe y se ilustra Zamia paucifoliolata, una nueva especie de cícada de las tierras bajas del Pacífico Colombiano del Valle del Cauca. Se distingue de otras especies de Zamia por su tallo subterráneo típicamente cargando hojas solitarias con 18 folíolos o menos, ejes estrobilares vellosos, presencia de microesporangios en el lado abaxial y adaxial de los microesporofilos, y semillas de mas de 18 mm de longitud. Se compara con Z. pyrophylla, Z. cunaria, y Z. ipetiensis, las especies a las que más se asemeja. 
Palabras clave: Chocó biogeográfico, sistemática, taxonomía