Chemical and Morphological Variation in the Cetraria islandica Complex in Iceland

Abstract

A study of collective lichen species Cetraria (L.) Ach. based upon some 3,000 individuals from 100 localities in Iceland shows that extreme morphological variation is not correlated with chemical variation (presence or absence of fumarprotocetraric acid). This is in striking contrast to high correlation of chemical and morphological characters in this species complex on European mainland, which serves there as basis for separation of C. sens. str. and C. ericetorum Opiz. Differences in geographical distribution of chemical characters, fertility, and range of morphological variability indicate that there are two ecological races in Iceland: 1) fumarprotocetraric acid-producing, nonfertile race with rather narrow morphological variability, mainly distributed along coasts and in more oceanic southern part of country, and 2) morphologically and chemically variable race (with or without fumarprotocetraric acid), frequently fertile, and distributed throughout Central Highlands and northern Iceland. In latter race, frequent occurrence of both chemical types within same morpho-phenotype at individual localities indicates that gene exchange may occur between fumarprotocetraric acid-producing and fumarprotocetraric acid-lacking plants. The related species Cetraria (L.) Ach. and C. ericetorum Opiz have long been considered distinct in Europe. Originally they were distinguished by morphological characters only, C. having broad, flat to involute lobes with numerous white pseudocyphellae all over lower side, and C. ericetorum having narrow, almost tubular lobes and lacking pseudocyphellae on lower side except along revolute edge. After thallus spot test with p-phenylendiamine (PD) was introduced, specific distinction of these taxa was strengthened by fact that all specimens of C. showed PD+ medullary reaction and all specimens of C. ericetorum PDreaction. But as later became apparent, this situation prevails only in Europe. Lynge (1921) considered C. ericetorum (then called C. crispa) a proper species, well separated from C. islandica after he studied lichen flora of Norway. His opinion changed, however, after experience with these taxa in Arctic. In his work on Greenland (1932) he wrote the specific difference is much less distinct in Arctic than in southern regions. After testing all of his specimens of C. 1 This study was supported by Grant No. GB-6041X from National Science Foundation. I thank Dr. William Louis Culberson for valuable suggestions and aid in preparing this paper and Dr. Chicita F. Culberson for help with chemistry. 2 Department of Botany, Duke University, Durham, North Carolina 27706. This content downloaded from 157.55.39.45 on Fri, 02 Sep 2016 04:46:26 UTC All use subject to http://about.jstor.org/terms 1969] KRISTINSSON: CETRARIA ISLANDICA IN ICELAND 345 complex from Spitsbergen and North-East Land with PD, he said (Lynge, 1938): ... well known morphological characters are so confluent, that they do not warrant reliable identification alone. We might, perhaps, quite as well unite . . . [C. and C. ericetorum] into one species with two types which are distinct chemically. Imshaug (1957) commented upon distinctness of variation in C. complex in Europe and confusing variation in it outside Europe and discussed possible history of group. Ahti (1964) pointed out that delimitation based upon chemical characters alone leads to very unnatural species grouping in this complex and suggested that separation based on morphological and ecological grounds may be possible-even though this would lead to inclusion of different chemical races within each species. Krog (1968) recorded different chemical constituents in C. specimens from Alaska, variation not only with regard to presence or absence of fumarprotocetraric acid but also with regard to rangiformic acid. The purpose of present paper is to analyze morphological and chemical variation in Cetraria group in Iceland. It is part of broad study of total lichen flora of that country.