How small is the smallest? New record and remeasuring of Scydosella musawasensis Hall, 1999 (Coleoptera, Ptiliidae), the smallest known free-living insect.

Alexey Polilov

doi:10.3897/zookeys.526.6531

Abstract

The smallest known beetle Scydosella musawasensis Hall is recorded for the second time. Precise measurements of its body size are given, and it is shown that the smallest examined representative of this species has a length of 325 µm.

Highlights

The smallest insects have recently attracted considerable attention as models for studying animal miniaturization, since they are among the smallest metazoans and since many morphological features unique to them and resulting from their extremely small size have been described (Polilov 2015)
Scydosella musawasensis was measured only from cleared specimens embedded in preparations for microscopy studies, which makes it difficult to measure length precisely
Measuring of ten specimens of S. musawasensis has shown that the smallest of them has a length of 325 μm, the largest has a length of 352 μm, and the average length is 338 μm (Fig. 1)

Summary

Introduction

The smallest insects have recently attracted considerable attention as models for studying animal miniaturization, since they are among the smallest metazoans and since many morphological features unique to them and resulting from their extremely small size have been described (Polilov 2015). LeConte (1863) described Ptilium fungi, specifying its length as ‘scarcely more than 1-100 of an inch,’ i.e., 254 μm. Motschoulsky (1868) almost simultaneously described Nanosella fungi from Georgia, North America, specifying its length 1/10 l., i.e., 212 μm (1 line = 2.116 mm).

Results

Conclusion