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ABSTRACTKaryotypes are presented for 19 taxa of Eucharis, Caliphruria, and Urceolina, a monophyletic group of Andean Amaryllidaceae within "infrafamily" Pancratioidinae Traub. All three genera are characterized by 2n = 46, the most common somatic number occurring in the "infrafamily." Incidences of polyploidy are low. Only two tetraploid (2n = 92) species of Eucharis are so far known, E. bouchei and E. bonplandii, the northernmost species of E. subg. Eucharis. The 2n = 68 karyotype of E. amazonica is interpreted as triploid-derived (3x -1). Chromosomal heteromorphism is reported for C. subedentata. Karyotype data is analyzed with principal component analysis and unweighted pairgroup cluster analysis. In a number of cases, phenetic relationships among the karyotypes correlate with phenetic and cladistic relationships based on morphological data. Karyotype evolution among the three genera is discussed in the context of classical theories of karyotypic symmetry. Stability of chromosome number in Eucharis and related genera suggests that chromosomal evolution has proceeded via nonreciprocal interchanges between chromosomes and infrachromosomal structural change. In at least one case (E. bakeriana), rapid sympatric speciation may have been vectored by chromosomal change. , 1963; Meerow, 1986), ecologically specialized to the understory of primary, rarely secondary, tropical rain forest below 2,000 m elevation. All three genera have petiolate leaves, and occur in edaphic situations of high fertility (Meerow, 1986). The genera separate on the basis of perianth, staminal, pollen, stigma, and seed morphology. As a group they represent a distinct tribal assemblage within "infrafamily" Pancratioidinae Traub (1957, 1963), a subfamily delimited by various patterns of staminal connation, a frequent somatic chromosome number of 2n = 46, and an Andean center of diversity (Meerow, 1985(Meerow, , 1986(Meerow, , 1987. The species are rare in nature, endemism is high, and several species in each genus are undoubtedly close to extinction. Eucharis is the largest and most widely '
EUCHARIS PLANCHON & LINDEN, Caliphruria Herbert and Urceolina Reichenbach form a monophyletic group of neotropical Amaryllidaceae (Traub