Instar sizes and growth in the Middle Permian monuran Dasyleptus brongniarti (Insecta: Machilida: Dasyleptidae)

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Andrew B. Heckert Ph.D., Professor (Creator)
Appalachian State University (ASU )
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Abstract: We used probability plotting to identify six sequential instars in the monuran Dasyleptus brongniarti Sharov, 1957. Data from 25 specimens from the Middle Permian (Ufimian) Kaltan locality in the Kuznetsk Formation in southwestern Siberia were used in the study. A probability plot of the statistical distribution of body lengths (excluding the caudal filament) shows six distinct normal component modes that represent size groups. The most parsimonious explanation of the size groups is that they represent instars. The component modes were resolved to yield the approximate mean size and standard deviation for each instar. These resolved instar data were then used to generate a partial growth curve that spans the range of 3.5 to 12 mm. The resolved instars of D. brongniarti compare favorably to those of the extant wingless insects, the silverfish, Lepisma saccharinum, and the bristletail, Petrobius. Using L. saccharinum as a model, the D. brongniarti instars probably represent numbers five through 10. The instar sizes generally obey Przibram’s rule, which predicts a doubling of mass and hence an increase of (factor of 1.26) in the linear dimensions at each molting. Our D. brongniarti data show body length increasing by a factor that varies between 1.13 and 1.37 at each instar, and averaging 1.24 over the six instars.

Additional Information

Rinehart, L.F., Rasnitsyn, A.P., Lucas, S.G., and Heckert, A.B., (2005) Instar sizes and growth in the Middle Permian monuran Dasyleptus brongniarti (Insecta: Machilida: Dasyleptidae). New Mexico Museum of Natural History and Science Bulletin 30, p. 270-272. (ISSN 1524-4156) Archived in NC DOCKS with permission of the editor. The version of record is available at:
Language: English
Date: 2005

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