Phyletic relationships indicate that Ephemerella bartoni Allen should be excluded from the subgenus Dannella in order to prevent a polyphyletic and impractical classifica- tion. A classification in the subgenus Eurylophella is more consistent with the species\u27 phyletic relationships

McCafferty, W. P

English

Valparaiso University

The Great Lakes Entomologist Volume 11 Number 3 - Fall 1978 Number 3 - Fall 1978 Article 4 October 1978 A Natural Subgeneric Classification of Ephemerella Bartoni and Related Species (Ephemeroptera: Ephemerellidae) W. P. McCafferty Purdue University Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation McCafferty, W. P. 1978. "A Natural Subgeneric Classification of Ephemerella Bartoni and Related Species (Ephemeroptera: Ephemerellidae)," The Great Lakes Entomologist, vol 11 (3) Available at: https://scholar.valpo.edu/tgle/vol11/iss3/4 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. THE GREAT LAKES ENTOMOLOGIST A NATURAL SUBGENERIC CLASSIFICATION O F  EPHEMERELLA BARTON1 A N D  RELATED SPECIES (EPHEMEROPTERA: E P H E M E R E L L I D A E ) ~  ABSTRACT Phyletic relationships indicate that Ephemerella bartoni Allen should be excluded from the subgenus Dannella in order to prevent a polyphyletic and impractical classifica- tion. A classification in the subgenus Eurylophella is more consistent with the species' phyletic relationships. The phyletic relationships within that g ~ o u p  of Ephemerella species which lack gills on abdominal segment 3 have recently been shown (McCafferty, 1977) and clearly indicate that each of the four subgenera within this group (Edmunds, 1959) are monophyletic. Independent of the phyletic study, Allen (1977) proposed modifications in the subgeneric limits within this group in order to accommodate a newly described species into the subgenus Dannella. Since E. bartoni Allen (known only from the larval stage) did "not fit the published characterization" of Dannella, this subgenus was radically redefined by Allen. The examination of E. bartoni material, in light of phyletic relationships and total larval characters, has indicated that its placement in Dannella is unnatural, and that Dannella, as redefined by Allen, is polyphyletic. The classificatory integrity of related subgenera was also weakened by this redefinition. E. bartoni shares the commonly derived character states of gill operculation, setaceousness, and lateral development of the abdomen with Eurylophella, Dannella, and Timpanoga. It thus can be easily excluded from consideration in Attenella. However, with only this much evidence, three possibilities regarding E. bartoni's phyletic position remain. I t  could be part of the Dannella-Timpanoga lineage, part of the Eurylophella lineage, or it could have evolved prior to the split into the above two lineages but after the origin of Attenella. E. bartoni does not possess either of the two exclusively derived character states which delimit the Dannella-Timpatzoga lineage, ie., the loss of denticles on the claws and the reduction of medial maxillary setae. The complete loss of dorsal abdominal tubercles is another derived character state which has previously characterized Danella, but is not found in E. bartoni. There is, therefore, no apparent phyletic evidence that would indicate a position on the Dannella-Timpanoga lineage. On the other hand, E. bartoni possesses three synapomorphic larval character states that delineate the Eurylophella lineage. This evolution included the loss of maxillary palpi, the apical rounding of the gills, and the reduction of the midlengths of abdominal segments 5, 6, and 7. The midlength of segment 9 shows a slight tendency towards elongation in my specimens of E. bartoni, although this is not the case in the figure of Allen (1977). Larval characters of E. bartoni clearly indicate that the species does not belong to the Dannella-Timpanoga lineage, but that its origin is with the Eu~lophel la  lineage. Ecologi- cal observations also lend support to this conclusion. Larvae of E. bartoni were found IPurdue Agricultural Experiment Station Journal No. 7066. a ~ e ~ a r t m e n t  of Entomology, Purdue University, West Lafayette, IN 47907. 1McCafferty: A Natural Subgeneric Classification of <i>Ephemerella Bartoni</i>Published by ValpoScholar, 1978138 THE GREAT LAKES ENTOMOLOGIST Vol. 11, No. 3 sparsely along the limestone shores of northern Lake Huron (D. R. Barton, pers. comm.) at less than 2 m depth and within 400 m of the shoreline. Patches of boulders or smaller stones and sometimes a fine layer of silt were present on the Limestone shelving substrate. Dannella species (McCafferty, 1977) are not known from lake habitats. Eulylophella species are commonly taken in lake habitats. In terms of the relative sizes of abdominal segments, E. bartoni is obviously not as highly specialized as other species of the Eulylophella lineage. Because of this, it can be inferred that E. bartoni is of relatively early origin in the Eulylopheh lineage. The species also demonstrates a unique condition of having dorsal abdominal tubercles on segments 5, 6, and 7 only. I t  remains to be seen whether or not adult males of E. bartoni possess the uniquely shaped penes typical of Eulylophella, or whether or not the eggs of E. bartoni have lost the polar cap (Koss, 1968) which is also typical of Eurylophella. These derived character states of other life stages may or may not have already been acquired in the Eurylophella lineage prior to the origin of E. bartoni. From all of the above, it is appropriate to exclude E. bartoni from the subgenus Dannella and thus maintain a natural classification. I would suggest, at least until adults and eggs of E. bartoni are known, that it be conservatively considered in the subgenus Eulylophella. The erection of a new subgenus to include this species may eventually be justified, possibly if, e.g., there prove to be large gaps in adult and egg characters between E. bartoni and other Eulylophella. In either case, a natural classification will have been retained. Dannella larvae will continue to key out effectively with the use of Edmunds et  al. (1976). E. bartoni will definitely not key to Dannella, but will only roughly key to Eulylophella. The special taxonomic characteristics, ecology, and distribution of this species should, therefore, be kept in mind. LITERATURE CITED Allen, R. K. 1977. A review of Ephemerella (Dannella) and the description of a new species (Ephemeroptera: Ephernerellidae). Pan-Pac. Entomol. 53:215-7. Edmunds, G. F., Jr. 1959. Subgeneric groups within the mayfly genus Ephemerella (Ephemeroptera: Ephemerellidae). Ann. Entomol. Soc. Amer. 52:543-7. Edmunds, G. F., Jr., S. L. Jensen, and L. Berner. 1976. The mayflies of North and Central America. Univ. Minn. Press, Minneapolis. Koss, R. W. 1968. Morphology and taxonomic use of Ephemeroptera eggs. Ann. EntomoL Soc. Amer. 61:696-721. McCafferty, W. P. 1977. Biosystematics of Dannella and related subgenera of Ephemerella (Ephemeroptera: Ephemerellidae). Ann. Entomol. Soc. Amer. 70:881-9. 2The Great Lakes Entomologist, Vol. 11, No. 3 [1978], Art. 4https://scholar.valpo.edu/tgle/vol11/iss3/4

A Natural Subgeneric Classification of \u3ci\u3eEphemerella Bartoni\u3c/i\u3e and Related Species (Ephemeroptera: Ephemerellidae)

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A Natural Subgeneric Classification of \u3ci\u3eEphemerella Bartoni\u3c/i\u3e and Related Species (Ephemeroptera: Ephemerellidae)

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