Geonoma orbignyana subsp. hoffmanniana (Wendland ex Spruce) Henderson

Henderson, Andrew, 2011, A revision of Geonoma (Arecaceae), Phytotaxa 17, pp. 1-271 : 113

45b. Geonoma orbignyana subsp. hoffmanniana (Wendland ex Spruce) Henderson , comb. & stat. nov.

Basionym: Geonoma hoffmanniana Wendland ex Spruce (1871: 106) . Type: COSTA RICA. Heredia: Volcán de Barba, no date, H. Wendland s.n. (holotype K!).

Geonoma molinae Glassman (1964: 7) . Type: NICARAGUA. Matagalpa: Santa María de Ostuma, between Matagalpa and Jinotega, 1300–1500 m, 8 January 1963, L. Williams, A. Molina , & R. Williams 23507 (holotype F!).

Inflorescences peduncular bracts 20.6(10.7–27.5) cm long; peduncles 32.4(20.9–56.0) cm long.

Distribution and habitat:— From 8°52’– 13°02’N and 82°33’– 86°20’W in Nicaragua, Costa Rica, and Panama at 2008(1400–3000) m elevation in montane rainforest ( Fig. 30 ).

This subspecies occurs in three separate areas; Nicaragua, the central part of Costa Rica, and eastern Costa Rica /western Panama.

There are six specimens from Nicaragua and these are small in size. There are no differences in any quantitative variable between these specimens and those of central Costa Rica, although they do occur at lower mean elevations (1475 m versus 2030 m).

In central Costa Rica specimens occur on three separate Cordilleras; Pacific slope on Tilarán (Monteverde), Atlantic slope on Central (Barva); and Pacific and Atlantic slope on Central. Specimens from Tilarán (Monteverde) have unbranched inflorescences, as does one specimen from Central. Specimens from Barva and the Pacific and Atlantic slopes of Central are small in size and similar to those from Nicaragua.

In eastern Costa Rica and western Panama, on the Talamanca, some specimens are also small (Davidse 26197, Fletes 1, Gamboa 708) but the others are the largest of any area, and occur at higher elevations. These specimens occur sympatrically with large specimens of G. undata subsp. edulis . Hammel et al. (2003) considered that larger specimens of subsp. hoffmanniana (as G. hoffmanniana ) and sympatric subsp. edulis (as G. edulis ) were ‘virtually indistinguishable’.

There is geographical variation in this subspecies. Regression shows there are significant associations between elevation and one plant, three leaf, and one inflorescence variable. Squared multiple R for the regression of stem height on elevation is 0.32, rachis width 0.24, basal pinna length 0.43, apical pinna length 0.33, and peduncle width 0.17. Values of these variables increase with increasing elevation. Stems become taller, rachis wider, basal and apical pinnae longer and peduncles wider with increasing elevation.

Figures

FIGURE 30. Distribution maps of Geonoma orbignyana subsp. hoffmanniana, G. paradoxa, G. pauciflora, and G. peruviana.