THE GEONOMA INTERRUPTA SPECIES GROUP

The Geonoma interrupta species group corresponds to Group 11 of Wessels Boer (1968).

The group is characterized by its flower pits spirally arranged; proximal lip of flower pits hooded, non-splitting at or before anthesis, the flowers exserted parallel to the rachilla; distal lip of flower pits absent; inner part of the pits hairy, at least distally; staminate flowers with six stamens; filaments with two, short, inflexed connectives and two, long, free thecae; pistillate flowers with the staminodial tube truncate or shallowly lobed at the apex.

The group is widespread in lowland to montane areas from southeastern Mexico through Central America and the Caribbean, and through northern and western South America.

Thirty-four names have been applied to the group, and between 14 (Burret, 1930), two (Wessels Boer, 1965), eight (Wessels Boer, 1968), and six (Wessels Boer, 1988) species have been recognized.

Four hundred and seventy-one herbarium specimens from AAU, BM, C, F, G, LE, MEXU, MO, NY, PMA, and US (herbarium abbreviations from Holmgren et al., 1990) were examined.

RESULTS

Seven binary or multistate attributes were found. Successive rounds of CA divided these into five binary or multistate characters and two binary traits (variables). Twenty-two quantitative characters were found (variables). Three are from stems, eight from leaves, and 12 from reproductive structures. Eighteen are continuous and four are discrete. Percentage missing values for each character are given under variables.

CA was performed on a matrix containing 354 specimens (117 omitted because of missing data) and the five qualitative characters. Results (not shown; cophenetic correlation = 0.95) show that seven major clusters are separated at the 0.75 similarity level. This is the level at which each of the clusters (i.e., character groups) is characterized by a unique combination of character states.

PCA and DA were not performed because of missing data. Character groups are listed in the order they appear in the phenogram, from the bottom, with species names in parentheses.

Character Group 1 (G. pinnatifrons). The group contains 169 specimens, and a further 33 (excluded because of missing qualitative data) were assigned to the group, based on morphology and geography.

Character Group 2 (G. vaga). The group contains 16 specimens, and a further 2 specimens were assigned to the group.

The next group contains 8 specimens, and a further 6 were assigned to the group. Based on geography, two groups of specimens can be recognized, both from Colombia - the Sierra Nevada de Santa Marta and the Chocó. There are significant differences in all quantitative characters between these two groups (t-test, P <0.01). These results, together with geographic distributions suggest that two separate geographic groups can be recognized. However, due to their morphological differences and geographical separation, I recognize two character groups here, 3 and 4.

Character group 3 (G. platybothros). The group contains 6 specimens.

Character group 4 (G. ramosissima). The group contains 8 specimens.

Character Group 5 (G. interrupta). The group contains 91 specimens, and a further 46 specimens were assigned to the group.

Character group 6 (G. euspatha). The group contains 35 specimens, and a further 15 specimens were assigned to the group.

Character Group 7 (G. rivalis). The group contains 3 specimens, and a further six were assigned to the group.

The next group contains 33 specimens, and a further seven were assigned to the group. Based on geography, two groups of specimens can be recognized; one from the Coastal Cordillera of Venezuela, and the other from Colombian Andes. One trait differs between these groups; the Venezuelan group has the proximal lips of the pits not hairy internally, or only along the margins, and the Colombian group has pits hairy proximally and distally internally. There are significant differences in 10 quantitative characters between these two groups (t-test, P <0.01). These results, together with geographic distributions suggest that two separate geographic groups can be recognized. However, due to their morphological differences and geographical separation, I recognize two character groups here, groups 8 and 9.

Character Group 8 (G. frontinensis). The group contains 12 specimens, and a further one was assigned to the group.

Character Group 9 (G. simplicifrons). The group contains 21 specimens, and a further six were assigned to the group.

KEY TO THE SPECIES OF THE G. INTERRUPTA SPECIES GROUP

1a. Leaves regularly pinnate with narrowly linear, 1-veined pinnae; rachillae hairs absent; eastern slopes of the Central Cordillera in Colombia..... G. rivalis.
1b. Leaves irregularly pinnate with multi-veined pinnae, sometimes intermixed with 1-veined pinnae, rarely simple, or rarely regularly pinnate but then the pinnae not narrowly linear nor 1-veined; rachillae hairs present. 2.

2a. Inflorescences erect, interfoliar, with slender peduncles, persistent, tubular bracts with the peduncular bract greatly exceeding the prophyll (and inserted well above it), and with few rachillae. 3.
2b. Inflorescences horizontal or pendulous, infrafoliar, with stout peduncles, deciduous, swollen bracts with the prophyll and peduncular bracts approximately equal (and inserted close together), and with numerous rachillae. 5.

3a. Rachillae tending to collapse between the pits on drying, the pits longer than wide; rachillae hairs to 0.1 mm long, at least some branched, these often bifurcate or trifurcate at or near the base; eastern Andean slopes of Colombia, Ecuador, Peru, and Bolivia, Guayana Highland region of Venezuela, Brazil, and the Guianas, and the Amazon region of Brazil..... G. euspatha.
3b. Rachillae remaining cylindrical on drying, the pits wider than long; rachillae hairs sparse, very short, wooly, soon falling. 4.

4a. Pits hairy proximally and distally internally; eastern slopes of the Cordillera Central and Cordillera Occidental in Colombia..... G. frontinensis.
4b. Proximal lip of pit not hairy internally, or only along the margins; Coastal Cordillera in Venezuela..... G. simplicifrons.

5a. Rachillae hairs to 0.1 mm long, at least some branched, often bifurcate or trifurcate at or near the base. 6.
5b. Rachillae hairs to 0.5 mm long, not or seldom branched. 8.

6a. Pistillate flowers mostly falling after anthesis (if not developing into fruits), the empty pits and proximal lips becoming narrowed; Mexico, Guatemala, Belize, Honduras, Nicaragua, Costa Rica, Panama, Colombia, Venezuela, Ecuador, and Peru..... G. interrupta.
6b. Pistillate flowers mostly persistent after anthesis, the pits not becoming narrowed. 7.

7a. Plant height 2.7(2.0-3.0) m; number of leaf divisions per side of rachis 5(4-5); orders of inflorescence branching 2; rachilla width 2.3(1.8-2.7) mm; Sierra Nevada de Santa Marta in Colombia..... G. platybothros.
7b. Plant height 5.1(3.5-8.0) m; number of leaf divisions per side of rachis 14(12-17); orders of inflorescence branching 4; rachilla width 1.7(1.1-2.3) mm; Pacific Coast and western slopes of Cordillera Oriental in Colombia..... G. ramosissima.

8a. Rachillae hairs straight; Mexico, Guatemala, Belize, Honduras, Nicaragua, Costa Rica, Panama, Colombia,Venezuela, Ecuador, Haiti, and the Lesser Antilles..... G. pinnatifrons.
8b. Rachillae hairs curly, intertwined; Península de Paria, Venezuela, the Northern Range, Trinidad, and Tobago.....G. vaga.