Revisiting the morphology of Lamproderma reveals incongruities among the taxonomic characteristics of higher classifications of Myxomycetes

ABSTRACT

Despite various attempts during the last few decades to establish a natural system for the Myxomycetes, researchers have not yet reached a consensus. One of the most drastic recent proposals is the movement of the genus Lamproderma, an almost a trans-subclass transfer. The traditional subclasses are not supported by current molecular phylogenies, and various higher classifications have been proposed during the last decade. However, the taxonomic characteristics on which the traditional higher classifications were based have not been reinvestigated. In the present study, the key species involved in this transfer, Lamproderma columbinum (the type species of the genus Lamproderma), was assessed using correlational morphological analysis of stereo, light, and electron microscopic images. Correlational analysis of the plasmodium, fruiting body formation, and the mature fruiting bodies revealed that several concepts of taxonomic characteristics that have been used to distinguish higher classifications are questionable. The results of this study indicate that caution is required when interpreting the evolution of morphological traits in Myxomycetes, as the current concepts are vague. The definitions of the taxonomic characteristics need a detailed research, and attention should be paid to the lifecycle timing of observations, before discussing a natural system for Myxomycetes.

KEYWORDS:

• Correlational analysis
• plasmodium
• slime molds
• slime sheath
• TEM

ACKNOWLEDGMENTS

The author thanks Hokkaido Government Kamikawa General Sub-Prefectural Bureau and the Ministry of Environment Japan, Hokkaido Higashikawa Bureau for their help to get permission for the research at Mt. Asahidake. The author acknowledges Drs. Hiromitsu Hagiwara and Tsuyoshi Hosoya from National Museum of Nature and Science, for their help to access invaluable literatures. The author thanks the anonymous reviewers for valuable comments on the earlier and very long version of this paper and their encouragement to divide it into two papers.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was partially supported by the Sasagawa Scientific Research Grant from the Japan Science Society (20-507) and JSPS KAKENHI Grant-in-Aid for Scientific Research C (19K06801).