CHROMOSOME NUMBERS IN THE MALVALES. II. NEW OR OTHERWISE NOTEWORTHY COUNTS RELEVANT TO CLASSIFICATION IN THE MALVACEAE, TRIBE MALVEAE

Abstract

Forty‐six chromosome counts from 29 species in 15 genera of Malvaceae, tribe Malveae are reported. Counts from 28 species and four genera, Bakeridesia Hochr., Hoheria A. Cunn., Plagianthus J. R. and G. Forster, and Robinsonella Rose and Baker, are new. These counts provide a basis for modifying a generic classification of the Malveae proposed by Bates in 1968. The identificaton of a heretofore unsuspected base chromosome number of x = 15, perhaps of ancient polyploid origin, has resulted in the realignment of Anoda Cav., Bakeridesia, Callirhoë Nutt., Napaea L., Periptera DC., and Sidalcea A. Gray. The data also support the thesis that the base chromosome number of the Malveae, or at least of the Abutilon alliance, is x = 8; that the genera of the New Zealand and Australian Plagianthus alliance were probably derived from abutiloid ancestors; that the generic boundaries of Pseudoabutilon R. E. Fries and Wissadula Medic. require redefinition; and that the Chilean Malacothamnus chilensis (Gay) Krapov. is generically distinct from the North American species of that genus. Callirhoë may be cytologically the most complex genus of Malveae. It includes both euploid and aneuploid series, probably supernumerary chromosomes, and perhaps structural rearrangements in the form of reciprocal trans‐locations between non‐homologous chromosomes.