CHROMOSOME SURVEYOF THE RUBIACEAE'Michael Kiehn2ABSTRACT The present knowledge of karyological characters, including basic numbers, ploidy levels, chromosome structures,karyotypes, interphase nuclear types, and DNA contents, and the broad range of variation for most of these characterswithin Rubiaceae (excluding Rubieae) are summarized. These data are related to the presently existing systematicconcepts of the family. The use of karyological characters is exemplified in some taxonomically critical groups:Subfamily Antirheoideae sensu Robbrecht appears heterogeneous with regard to basic numbers and chromosomestructure; it contains chromosomally homogeneous tribes (e.g., Vanguerieae or Guettardeae), but also g:oups withinternal variation (such as the tribe Knoxieae or the genus Chiococca). Available chromosome data of the tribeCinchoneae sensu Robbrecht seem to be in accordance with its morphologically and molecular-based subdivision inthree tribes: viz. Cinchoneae s. str., Calycophylleae, and Coptosapelteae. The tribe Chiococceae sensu Bremer consistsof at least two distinct entities characterized by their chromosome morphology and basic numbers: the former tribeCondamineeae, and the genera Chiococca and Exostema. A possible subdivision of Rondeletia is indicated by threedifferent basic numbers (x = 9, x = 10, x = 11) occurring in the genus, while chromosome data give no hintsregarding the position of Wendlandia and Sipanea in the tribe Rondeletieae. The tribe Isertieae comprises generawith basic numbers of x = 9, x = 10, and x = 11. Thus the tribal position of Acranthera (x = 10), Heinsia (x =11), and Mycetia (x = 11) cannot be decided on the basis of chromosome numbers alone. Sabicea has taxa witheither x = 9 or x = 11; morphological studies are required to check the generic delimitations. The close relationshipof Pauridiantha and Urophyllum is supported by karyomorphology and basic number. A possible origin of theSpermacoce out of the tribe Hedyotideae is discussed. With more than 10,000 species (Mabberley,1987) the Rubiaceae are one of the larger familiesin the plant kingdom. Karyological studies in thefamily show a broad range of variation in chro-mosome numbers and other chromosomal param-eters. Compilations of karyological data, however,are either relatively old (Fagerlind, 1937; Mendes,1938), regionally restricted (Mangenot & Man-genot, 1958: West Africa; Philip & Mathew, 1988:southern India), or not widely published (Kiehn,1986a). Relatively numerous counts are publishedfor Africa, India (especially southern India), andNew Zealand, and many unpublished data (by theauthor) exist for Central America and Madagascar.For most other tropical and subtropical areas ofthe world karyological information on Rubiaceaeis scanty. Otherwise, recent chromosome countsof Rubiaceae are scattered in the literature andnot easily accessible to taxonomists. Besides thework on the temperate Rubieae, which are notdiscussed in this survey, only few attempts of moreintensive chromosome studies on material of knownorigin related to larger systematic groups have beenmade (Hedyotideae: Lewis, 1962, 1965; Antho-spermeae: Puff, 1986; Paederia: Kiehn, 1991). Earlier interpretations of chromosome data re-lated to evolutionary trends and classification ofRubiaceae mostly dealt with basic numbers andploidy levels (e.g., Verdcourt, 1958; Lee & Rink,1985; Philip & Mathew, 1988). They were basedon different systematic groupings of Rubiaceae(Schumann, 1891; Verdcourt, 1958; Wagenitz,1959; Bremekamp, 1966) because a comprehen-sive multidisciplinary systematic survey of tropicalRubiaceae has been lacking until recently (Rob-brecht, 1988). In the present paper the subfamilial,tribal, and subtribal classification of the Rubiaceaelargely follows Robbrecht (1988) but also considersmore recent publications that discuss the circum-scription and composition of Robbrecht's tribes (e.g.,Andersson & Persson, 1991: Cinchoneae, Con-damineeae; Bremer, 1992: Chiococceae; Bremer I' am indebted to F. Ehrendorfer for kindly checking and discussing the manuscript, to U. Schachner for assistancein preparing the manuscript, and to the reviewers and editors for helpful comments. I thank C. M. Taylor and theMissouri Botanical Garden for the invitation to present this paper at the "International Conference on the Systematicsof the Rubiaceae," 4-6 Oct. 1993, in St. Louis. Parts of the work have been financially supported by the "Oster-reichische Forschungsgemeinschaft" (proj. 06/2582) and the "Hochschuljubiliumsstiftung der Stadt Wien" (proj.H-46/92). 2 Institute of Botany and Botanical Garden, University of Vienna, Rennweg 14, A-1030 Vienna, Austria.ANN. MISSOURI BOT. GARD. 82: 398-408. 1995.
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