Geonoma deversa subsp. deversa

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Discussion

  • There is a single specimen (Henderson 3024) from Herrera, Panama, isolated from others, which resembles specimens of subsp. peninsularis, particularly in its short peduncle and long rachillae, and it may represent a distinct subspecies. Specimens from central Panama, from the Santa Rita Ridge to western San Blas have different shaped leaves, with shorter basal and apical pinnae with wider angles. Such specimens are also found just to the northeast of the Osa Peninsula, sympatric with subsp. peninsularis. Several specimens, particularly from white sand regions of the Rio Negro in Venezuela and Brazil, but also less commonly from other areas, have regularly pinnate leaves with numerous pinnae with 1 main vein only. Some of these are reported to be rheophytes. A few specimens, forming an isolated population in Pasco, Peru, are considerably smaller than others. They have wider basal pinna angles and sigmoid pinnae. The type of G. killipii is one of these specimens, and they are recognized as the killipii morphotype. Potential hybrids between this morphotype and G. brongniartii are discussed under that species. There are several other areas where hybrids are suspected with other taxa. All these potential hybrids have been excluded from the above descriptions and analyses. Specimens from the northeastern part of the range of the subspecies, in Suriname, French Guiana, and Brazil (Amapá, Pará), are intermediate in morphology between that of subsp. deversa and the sympatric G. leptospadix. Some of these specimens have leaves like those of subsp. deversa and triad arrangement approaching that of G. leptospadix; some have leaves of G. leptospadix and triad arrangement of subsp. deversa. These specimens are hypothesized to be hybrids between the two taxa. There are a few otherspecimens from this region which also appear somewhat intermediate, but are determined as subsp. deversa. A hybrid zone may exist running from Suriname and French Guiana to Brazil (Amapá, Pará). There is considerable variation in the western Amazon region, and there may also be hybrid zones here, especially in Peru (Loreto) and Brazil (Acre). Specimens from near Iquitos (iquitos morphotype) differ from other specimens of subsp. deversa in 13 variables (plant height, stem diameter, petiole length, rachis length, rachis width, basal pinna length, interbract distance, peduncle length, peduncle width, rachilla length, rachilla width, number of rachillae, fruit diameter)(t-test, P <0.05). On the other hand, the same specimens differ from the sympatric subsp. quadriflora in only four variables (peduncle width, rachilla width, fruit length, fruit diameter) (t-test, P <0.05). These results indicate that the iquitos morphotype may represent hybrids between subsp. deversa and subsp. quadriflora (specimens of subsp. quadriflora may have tricussate pits at the apices of the rachillae, and one specimen of subsp. deversa (Croat 20340) contains two inflorescences, one with quadricussate pits and the other with tricussate pits). Some specimens from the western Amazon region of Brazil (Acre, Amazonas) differ from the more typical subsp. deversa in their longer leaves with more pinnae, and shorter, thicker peduncles. In their leaves they resemble subsp. quadriflora and in their inflorescences they resemble G. occidentalis, and they occur in an area between the ranges of these two taxa. They may be hybrids between subsp. quadriflora and G. occidentalis, or between one of these taxa and subsp. deversa. The type specimen of G. myriantha appears to represent one of these possible hybrids. (Henderson, A.J. (2011) A revision of Geonoma. Phytotaxa 17: 1-271.)A

Description