Revisión taxonómica de las especies costarricenses del complejo de Geonoma edulis (Arecaceae)
Fecha
2025-01
Tipo
tesis de maestría
Autores
Ramírez Ortiz, Ramón Antonio
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Resumen
Con ca. 68 especies, Geonoma Willd. (subfamilia Arecoideae) es el género más grande de la tribu Geonomateae y el tercer género más grande de palmeras neotropicales. Debido a su amplia variación morfológica, la taxonomía a nivel de especie de este género ha sido controversial, con una gran discrepancia histórica en el número de especies reconocidas. Geonoma se distribuye desde México hasta Bolivia, Paraguay y el sur de Brasil, además de las Antillas. En Costa Rica se reportan 15 especies según la sinopsis más reciente del género para el país. Es relativamente fácil distinguir las especies de Geonoma de tierras bajas de Costa Rica, pero existe un complejo de especies montanas que son muy variables y taxonómicamente difíciles. Como consecuencia, su taxonomía ha sido pobremente comprendida y su circunscripción ha sido controversial. Estas especies montanas corresponden al complejo conformado por G. edulis H. Wendl. ex Spruce, G. hoffmanniana H. Wendl. ex Spruce y G. talamancana Grayum. En este trabajo presento una revisión taxonómica de estas especies, a partir del análisis morfométrico de 18 variables morfológicas cuantitativas y 17 cualitativas. Examiné un total de 229 especímenes, provenientes tanto de herbario como de campo. Evalué el grado de similitud morfológica entre las especies, mediante un análisis de conglomerados (Distancia euclideana, Single linkage), basado en los promedios de las variables cuantitativas. Mediante la comparación de los gráficos de cajas y bigotes de estas variables, analicé el nivel de traslape morfológico entre las especies, y lo clasifiqué como alto (50–100% de similitud), moderado (5–35%) o nulo (0–5%). Hallé un extensivo traslape entre las especies, en la mayoría de variables analizadas. Geonoma talamancana quedó separada de las demás especies, fundamentalmente, por la ausencia de bráctea peduncular, y por tener inflorescencias espigadas con pedúnculos más largos. Geonoma edulis quedó finalmente separada de G. hoffmanniana por presentar inflorescencia infrafoliar, no espigada, ramificada en 1–3 órdenes, con 25 (6–108+) raquillas; con el pedúnculo de 19.8 (8–37) cm de longitud y 10.6 (2.1–18.5) mm de diámetro; y con la bráctea peduncular incluida en el profilo y unida 3.1 (0.8–5.7+) cm por encima del mismo, presentándose ambos ensanchados en el centro y no ceñidos estrechamente al pedúnculo. Geonoma hoffmanniana fue finalmente distinguida de G. edulis por tener inflorescencia interfoliar, espigada o ramificada en 1–2 órdenes, con 5 (1–8+) raquillas; con el pedúnculo de 41.3 (21.5–62) cm de longitud y 4.9 (1.5–7.5) mm de diámetro; y con la bráctea peduncular exserta del profilo y unida 13.4 (5.3–24.9) cm por encima del mismo, siendo ambos estrechos, ceñidos estrechamente al pedúnculo. El análisis de la variación intraespecífica me permitió caracterizar dos morfotipos a lo interno de G. edulis y tres a lo interno de G. hoffmanniana, que presentan diferencias en su distribución geográfica, el orden de ramificación de la inflorescencia, el número de raquillas y el tamaño general de los individuos y sus partes. Encontré que G. edulis y G. hoffmanniana presentan flores en antesis y frutos a lo largo de todo el año. Geonoma talamancana fue reportada con flores o frutos en febrero, marzo, abril, agosto y octubre. La antesis era carpelada en más de la mitad de los casos registrados, pero solamente alrededor del 20% de los ejemplares examinados tenía antesis estaminada. No hay información sobre polinización y dispersión de frutos en el complejo de G. edulis. Registré la presencia de agallas en 10 ejemplares de G. hoffmanniana y tres de G. talamancana. El rango altitudinal del complejo de G. edulis fue reportado desde 700 hasta 3100 msnm, presentando picos de abundancia en 1500–1800 msnm. Finalmente, en este trabajo apoyo y justifico el reconocimiento de G. edulis y de G. hoffmanniana como especies en vez de subespecies. Este proyecto contribuye a una mayor comprensión de la variación morfológica, geográfica y fenológica de Geonoma en Costa Rica y el Neotrópico, y arroja luz sobre la identidad de las especies costarricenses del complejo de G. edulis.
With ca. 68 species, Geonoma Willd. (subfamily Arecoideae) is the largest genus of the tribe Geonomateae and the third largest genus of Neotropical palms. Due to its wide morphological variation, the species-level taxonomy of this genus has been controversial, with a large historical discrepancy in the number of recognized species. Geonoma is distributed from Mexico to Bolivia, Paraguay and southern Brazil, in addition to the Antilles. In Costa Rica, 15 species are reported according to the most recent synopsis of the genus for the country. It is relatively simple to distinguish Geonoma species from the lowlands of Costa Rica, but there is a complex of montane species which are highly variable and taxonomically difficult. As a consequence, their taxonomy has been poorly understood and their circumscription has been controversial. These montane species correspond to the complex made up of G. edulis H. Wendl. ex Spruce, G. hoffmanniana H. Wendl. ex Spruce and G. talamancana Grayum. In this work I present a taxonomic revision of these species, based on the morphometric analysis of 18 quantitative and 17 qualitative morphological variables. I examined a total of 229 specimens, coming from both herbaria and the field. I evaluated the degree of morphological similarity between the species, using a cluster analysis (Euclidean distance, Single linkage), based on the averages of the quantitative variables. By comparing box and whisker plots of these variables, I analyzed the level of morphological overlap between species, classifying it as high (50–100% similarity), moderate (5–35%), or none (0–100% similarity). 5%). I found an extensive morphological overlap between the species in most of the variables analyzed. Geonoma talamancana was separated from the other species, fundamentally, by the absence of a peduncular bract, and by having spiked inflorescences with longer peduncles. Geonoma edulis was finally separated from G. hoffmanniana due to its infrafoliate, non-spike inflorescence, branched in 1–3 orders, with 25 (6–108+) rachillas; with the peduncle 19.8 (8–37) cm long and 10.6 (2.1–18.5) mm in diameter; and with the peduncular bract included in the prophylum and attached 3.1 (0.8–5.7+) cm above it, both being widened in the center and not closely attached to the peduncle. Geonoma hoffmanniana was finally distinguished from G. edulis by having interfoliate inflorescence, spiked or branched in 1–2 orders, with 5 (1–8+) rachillas; with the peduncle 41.3 (21.5–62) cm long and 4.9 (1.5–7.5) mm in diameter; and with the peduncular bract exserted from the prophylum and united 13.4 (5.3–24.9) cm above it, both being narrow, closely fitting to the peduncle. The analysis of intraspecific variation allowed me to characterize two morphotypes within G. edulis and three within G. hoffmanniana, which present differences in their geographical distribution, the order of branching of the inflorescence, the number of rachillas and the general size of individuals and their parts. I found that G. edulis and G. hoffmanniana present flowers in anthesis and fruits throughout the year. Geonoma talamancana was reported with flowers or fruits in February, March, April, August and October. The anthesis was carpellate in more than half of the recorded cases, but only about 20% of the specimens examined had staminate anthesis. There is no information on pollination and fruit dispersal in the G. edulis complex. I recorded the presence of galls in 10 specimens of G. hoffmanniana and three of G. talamancana. The altitudinal range of the G. edulis complex was reported from 700 to 3100 masl, presenting peaks of abundance at 1500–1800 masl. Finally, in this work I support and justify the recognition of G. edulis and G. hoffmanniana as species instead of subspecies. This project contributes to improve the understanding of the morphological, geographical and phenological variation of Geonoma in Costa Rica and the Neotropics, and sheds light on the identity of the Costa Rican species of the G. edulis complex.
With ca. 68 species, Geonoma Willd. (subfamily Arecoideae) is the largest genus of the tribe Geonomateae and the third largest genus of Neotropical palms. Due to its wide morphological variation, the species-level taxonomy of this genus has been controversial, with a large historical discrepancy in the number of recognized species. Geonoma is distributed from Mexico to Bolivia, Paraguay and southern Brazil, in addition to the Antilles. In Costa Rica, 15 species are reported according to the most recent synopsis of the genus for the country. It is relatively simple to distinguish Geonoma species from the lowlands of Costa Rica, but there is a complex of montane species which are highly variable and taxonomically difficult. As a consequence, their taxonomy has been poorly understood and their circumscription has been controversial. These montane species correspond to the complex made up of G. edulis H. Wendl. ex Spruce, G. hoffmanniana H. Wendl. ex Spruce and G. talamancana Grayum. In this work I present a taxonomic revision of these species, based on the morphometric analysis of 18 quantitative and 17 qualitative morphological variables. I examined a total of 229 specimens, coming from both herbaria and the field. I evaluated the degree of morphological similarity between the species, using a cluster analysis (Euclidean distance, Single linkage), based on the averages of the quantitative variables. By comparing box and whisker plots of these variables, I analyzed the level of morphological overlap between species, classifying it as high (50–100% similarity), moderate (5–35%), or none (0–100% similarity). 5%). I found an extensive morphological overlap between the species in most of the variables analyzed. Geonoma talamancana was separated from the other species, fundamentally, by the absence of a peduncular bract, and by having spiked inflorescences with longer peduncles. Geonoma edulis was finally separated from G. hoffmanniana due to its infrafoliate, non-spike inflorescence, branched in 1–3 orders, with 25 (6–108+) rachillas; with the peduncle 19.8 (8–37) cm long and 10.6 (2.1–18.5) mm in diameter; and with the peduncular bract included in the prophylum and attached 3.1 (0.8–5.7+) cm above it, both being widened in the center and not closely attached to the peduncle. Geonoma hoffmanniana was finally distinguished from G. edulis by having interfoliate inflorescence, spiked or branched in 1–2 orders, with 5 (1–8+) rachillas; with the peduncle 41.3 (21.5–62) cm long and 4.9 (1.5–7.5) mm in diameter; and with the peduncular bract exserted from the prophylum and united 13.4 (5.3–24.9) cm above it, both being narrow, closely fitting to the peduncle. The analysis of intraspecific variation allowed me to characterize two morphotypes within G. edulis and three within G. hoffmanniana, which present differences in their geographical distribution, the order of branching of the inflorescence, the number of rachillas and the general size of individuals and their parts. I found that G. edulis and G. hoffmanniana present flowers in anthesis and fruits throughout the year. Geonoma talamancana was reported with flowers or fruits in February, March, April, August and October. The anthesis was carpellate in more than half of the recorded cases, but only about 20% of the specimens examined had staminate anthesis. There is no information on pollination and fruit dispersal in the G. edulis complex. I recorded the presence of galls in 10 specimens of G. hoffmanniana and three of G. talamancana. The altitudinal range of the G. edulis complex was reported from 700 to 3100 masl, presenting peaks of abundance at 1500–1800 masl. Finally, in this work I support and justify the recognition of G. edulis and G. hoffmanniana as species instead of subspecies. This project contributes to improve the understanding of the morphological, geographical and phenological variation of Geonoma in Costa Rica and the Neotropics, and sheds light on the identity of the Costa Rican species of the G. edulis complex.
Descripción
Palabras clave
complejo de Geonoma undata, especiación de plantas, Geonomateae, morfometría de plantas, sistemática de palmeras, taxonomía vegetal, Geonoma undata complex, palms systematics, plants morphometry, plants speciation, plants taxonomy