PALEOZOIC LYCOPSID FRUCTIFICATIONS. III. CONSPECIFICITY OF BRITISH AND NORTH AMERICAN LEPIDOSTROBUS PETRIFACTIONS

A study was made of 30 apparently similar microsporangiate cone specimens of the lycopsid fructification Lepidostrobus found in coal balls of Middle Pennsylvanian age from Illinois and Kansas. None of these specimens was a complete cone, but at least 19 were large enough and well enough preserved to provide information regarding variation both within one cone and among several specimens. The data obtained substantiated the original assumption that all 30 specimens represented one species. Attempts to equate this one species with any of the similar, previously described North American taxa, Lepidostrobus coulteri, L. pulvinatus and Lepidocarpon magnificummicrosporangiate form, and the British taxon Lepidostrobus oldhamius, including the forms (a), (p3), (y) and pilosus, revealed that no significant differences existed among any of these taxa. Furthermore, all characteristics described for these taxa were referable to, and well within the range of variation of, the one species here analyzed. Differences among the taxa were found to represent only differences in maturation or normal variation. All these taxa are, therefore, conspecific and are assigned to one species which by priority is named Lepidostrobus oldhamius. The common association of the megasporangiate Lepidocarpon lomaxi with all these microsporangiate cones, now recognized as representing the single taxon Lepidostrobus oldhamius, is strong evidence for the probability that Lepidocarpon lomaxi and Lepidostrobus oldhamius were produced by the same parent plant species. IN A STUDY of the lycopsid cone-genus Lepidostrobus in coal balls from Middle Pennsylvanian strata of Illinois and Kansas, 30 specimens were found. They seemed apparently all of one kind. This relatively large number of cones, if indeed composed of specimens all of only one kind, represented a fine opportunity to determine the characteristics and the range of variation of that cone species. Nineteen of the best preserved of these cones were intensively analyzed, yielding ample data that showed conclusively that only one species was represented by all 30 specimens. In the work of determining the identity of this species, it was found that the specimens possessed many characters considered diagnostic for the previously described taxa Lepidostrobus oldhamius Will.2 (1893); L. oldhamius Will., (a), ((), (y) Maslen (1899); L. oldhamius Will., f. pilosus Arber (1914); L. coulteri Jongmans (1930); L. pulvinatus Felix (1954), and Lepidocarpon magnificum Andrews and Pannell (1942) (microsporangiate form). Three observations, considered together, were of significant note: (1) the diagnoses of all these previously described taxa were based on very ' Received for publication 22 August 1966. Portion of a dissertation submitted in partial fulfillment of the requirements for the degree Doctor of Philosophy in the Department of Botany of the University of Illinois. 2 The type material originally described by Williamson as L. oldhamius was later designated the (a) form of the species by Maslen. few specimens; (2) the distinguishing characteristics, particularly of the American taxa, were not completely elucidated nor shown to be mutually exclusive; (3) the specimens of this present study showed a range of variation that encompassed the descriptions given for all these earlier described taxa. These observations showed that characters considered to be distinctive by previous investigators might be expressions of variation within one species, and, therefore, the possibility existed that these seven taxa might all be conspecific. As a result the task of identifying the species represented by the 30 specimens resolved itself into a reexamination of the type specimens of the aforementioned taxa, a reevaluation of the criteria cited in the diagnoses, and an effort to determine the real differences among them. MATERIALS AND METHODS-Thirty cone specimens were found in coal balls of the Herrin (No. 6) coal of Middle Pennsylvanian age from the Farmington and Carrier Mills localities in Illinois (Balbach, 1965) and of the Bevier coal, Bevier formation, Cherokee group, Desmoinesian series of the Middle Pennsylvanian from the Mackie-Clemens No. 23 Mine locality, Sec. 22, T29S, R29E, Washington Twp., Crawford Co., Kan., Mulberry quadrangle (15' series). Of these, 19 of the best preserved were intensively studied. All were relatively large, ranging from