RECONSIDERATION OF DALDINIA CONCENTRICA BASED UPON A RECENTLY DISCOVERD SPECIMEN

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Jack
Yu-Ming Ju
Michael J. Adams

 In 1997 a revision of Daldinia was published (Ju et al., 1997). One of the main problems facing the authors was the application of the name of the type species, Daldinia concentrica (Bolton: Fr.) Ces. & De Not., in the absence of type material. Child (1932), the monographer of the genus, had a broad concept of D. concentrica that, in the opinion of Ju et al. (1997), embraced several distinct taxa. Among the characters utilized by Ju et al. (1997), but not by Child (1932), were the color of stromatal pigments in 10% KOH and cultural features, including anamorphic data. Using stromatal pigment color in KOH (or the absence of pigment color) as the primary character to separate taxa, two species clusters emerged: a cluster of three species with more or less yellow pigments and a cluster of sixteen species with more or less purple pigments or with pigments apparently lacking altogether. One of the yellow-pigmented taxa is widespread throughout the world, particularly in temperate and subtropical regions (Ju et al., 1997). This taxon had been accepted by Child (1932), and virtually every other mycologist following her, as D. concentrica. Unfortunately, in the British Isles—the type location for D. concentrica—a purple-pigmented taxon had long been accepted as D. concentrica. Child (1932) did not distinguish between yellow-pigmented and purple-pigmented material in her concept of D. concentrica.

It had long been assumed that no Bolton material of D. concentrica is extant. Thus, we felt justified in using Bolton's painting of D. concentrica as type (Bolton, 1789). But what taxon was really represented by Bolton's illustration—the purple-pigmented taxon commonly accepted in the British Isles as D. concentrica or the yellow-pigmented taxon accepted in much of the rest of the world as D. concentrica? As will be discussed later, the fungus traditionally considered to be D. concentrica in the British Isles occurs commonly on Fraxinus and, indeed, Daldinia on other hosts should be examined carefully to be certain of their identities. Yet, Bolton's collection was made from "old thorns" (Bolton, 1789), probably a Crataegus sp. or even Prunus spinosa , and in his notes in the possession of Roy Watling he indicates that he had found it "in a less perfect state on an hasel stock," i.e., Corylus. Moreover, yellow-pigmented specimens under Sphaeria concentrica and S. fraxinea, with unknown localities, were examined from the Persoon herbarium and the yellow-pigmented taxon occurs in Europe (Ju et al., 1997). Although Ju et al. (1997) had never seen yellow-pigmented stromata among British Isles material prior to writing the revision they believed that it could occur there owing to the proximity to mainland Europe. It was thus considered that accepting Bolton's illustration as depicting a yellow-pigmented taxon representing the type of D. concentrica would inconvenience the fewest workers worldwide (not in the UK!). Ju et al. (1997) also erected D. petriniae Y.-M. Ju, J. D. Rogers, & San Martín for a purple-pigmented fungus that produces short, annellated conidiophores. They supposed a very similar purple-pigmented fungus in British Isles, Europe, and elsewhere, differing primarily in having a typical Nodulisporium Preuss anamorph, would eventually have to be named. That problem was not dealt with at the time of the revision owing to the lack of culturable material.

Prior to this time Roy Watling had purchased Bolton's original painting of Sphaeria concentrica as an interleaved inclusion in a copy of "History of fungusses" that had apparently belonged to Edward Robson of Darlington. Watling with the aid of Alan W. Legg of Darlington began to investigate the life and activities of this correspondent and friend of Bolton. The matter stood thus until mid-winter, 1998 when Watling informed J. D. Rogers that herbarium sheets bearing specimens of Robson had been discovered at Sunderland Museum and called to his attention by Legg. The significance of this discovery was summarized aptly by Legg (1997), "Of far more historical significance is the fact that many of the herbarium sheets appear to be the original ones sent by Robson to Bolton and returned by the latter with comments. Not only do they bear at least four of Bolton's own collections, but some of them shed light on the real or likely identity of fungi illustrated and described by Bolton and his contemporaries which have posed problems of determination for later mycologists up to the present day." Accordingly, with great excitement and anticipation RW and JDR visited the Sunderland Museum in the company of A. W. Legg and examined the Robson material.

The Robson material consists of sections of a Daldinia stroma 2-3 mm thick and up to about 7 cm diam mounted on sheets, and some loose debris. Perithecia did not appear to be present, but a thorough search could not be made without destroying material. Fragments of material immersed in KOH released a purplish pigment. The material was labelled, as follows: "Sphaeria concentrica Mss; Lycoperdon fraxin Huds?; on stumps placed for seats in Captn Hope's pleasure grounds." According to Legg (1997) material of this collection sent from Darlington by Robson to Bolton might have been used for Bolton's illustration (Bolton, 1789); the layout and the constituents of the painting have numerous common features. Thus, although the host substrate is uncertain and the location of Hope's pleasure grounds has not been pinpointed, it is obvious that this material is of great importance in clarifying Bolton's concept of Sphaeria concentrica. There can be little doubt that the material that he figured and described was a purple-pigmented taxon that occurred, among other hosts, on Fraxinus. We thus emend our concept of Bolton's illustration (1789) based upon Robson's material and, consequently, Daldinia concentrica (see later).

In order to establish the frequency and distribution of D. concentrica in the British Isles the large Daldinia collection of A. J. S. Whalley was examined in detail. Several interesting facts have emerged:

  1. Daldinia concentrica is commonly encountered on Fraxinus in the British Isles. It is also represented in the collections from Fagus and Sorbus.
  2. Daldinia petriniae is apparently not represented in the material examined, based on stromatal surface morphology. Cultures could not be made from most of the material, however, and the anamorph is the most reliable character for separating this species from D. concentrica.
  3. The Daldinia on Betula is D. loculata (Lév.) Sacc., not D. concentrica as commonly supposed.
  4. The single collection from Ulmus is D. grandis Child.
  5. No taxa with yellow pigments have been seen among the many specimens examined from the British Isles.