eiochemicM Systetr~tics end Ecology. Vol. 13. No. 3. pp. 239-250. 1985. 0305--1978•85 $3.00+0.00 Pdnted in Great Britain. © 1985 Pergamon Pros Ltd. A New Species of Muscari Subgenus Leopoldia from the Iberian Peninsula M. RUIZ REJON, L. PASCUAL, C. RUIZ REJON, B. VALDES* and J. L. OLIVERt Departamento de Gen6tica, Facultad de Ciencias, Universidad de Granada, Spain; "Dapartamento de Bot~nica, Facultad de Biologia, Univendded de Sevilla, Spain; tDepartamento de Gen6tice, Facultad de Ciencias, Universided Autbnoma de Madrid, Cantoblanco, Madrid 34, Spain Key Word Index~Musca¢i comosum; Muscati rnatritensis sp. nova; Leopo/dia; Muscar~, Utlace~ cytogenetic analysis; electro~orezic analysis; morphological analysis; breeding systems; speciation process. Abstract--The biological analysis of s~weralpopulations confirms the existence in the Ibe~an Peninsula of two species of Muscan" subgenus Leopo/dia: M. comosum and M. rnatr/tens~ (the latter described as new). Karyologically, they differ in at least a translocation rearrangement, in the presence of heterochromatin, which is lacking in M. trmtr/tens/s, and in some chromosomal characters. At the genic level, the distance between M. comosum and M. matr/tens~ is high (0.378). Morphologically, they show some differences in floral structure which are correlated with different reproductive systen~, allogamy in M. comosum and autogerny in M. matritensis. The possible evolutionary relationships between these taxa is discussed. Introduction Understanding the dynamics of the speciation process is of central importance to the study of evolution. It is of particular interest to know what changes (physiological, developmental, behavioural, ecological, chromosomal) are dir- ectly associated with evolution or reproductive isolation, how rapidly and under what circum- stances (allopatry, sympatry, etc.) such changes occur, and the relative importance of selection and stochastic factors in producing these changes. A widely accepted model of geographic speciation [1,2] suggests that new species arise in isolated populations through the gradual accumulation of genetic differences. However, it has become increasingly clear that speciation events do not always conform to this pattern [3-5]. Alternative models of speciation have been developed to explain observed relation- ships among closely related species. These include models of sympatric and quantum speciation, for example. In this latter model, the chromosome rearrangements, or polyploidy, can play important roles as rapid reproductive iso- lation mechanisms. In these cases the genetic (Received 16 March 1984) distances and the degree of morphological differentiation between related species are very low [6-13]. Muscari Miller subgenus Leopoldia (Pad.) Zahar or Leopoldia Pad. (refs [14, 15], respec- tively) is a critical biological complex in which the delimitation of taxa is, to a certain extent, arbitrary. The geographical distribution of the subgenus is centred in the Mediterranean region and extends from the Canary Islands to Afghanistan and from central Germany and southern U.S.S.R. to north Africa. Although many species have been described for this subgenus, most of them probably do not deserve taxonomic recognition. According to Bentzer [16], this group includes ca. 20 species, six of which have been reported for the European flora [14]. Five of these (IV~.cycladicum, M. gussonei, M. spreitzenhoferi, M. weissi and M. ten- uiflorum) occur in the central and eastern Mediterranean region in 'phrygana' com- munities (dwarf scrub communities) [17] or in dry places, where most have a rather reduced geographical area. In contrast, M. comosum (L.) Miller, the only species of this subgenus so far reported from the western Mediterranean, has a wider ecological tolerance and grows in dry grasslands and cultivated ground over most of the Mediterranean area. 239