A new needle stonefly with parasitic mites from the Eocene Baltic amber

Baltileuctra dewalti Chen sp. nov., a new extinct species of needle stoneflies (Leuctridae, Plecoptera), is described and illustrated from the Eocene Baltic amber and compared to the other leuctrids. Baltileuctra dewalti Chen sp. nov. differs from both extant and extinct representatives of Leuctridae by a combination of morphological characters including wing venation, unique terminalia structures, and cercal modification. The most distinguishable character for the new taxon is the presence of two dentate long spines lateral to a well-developed subanal probe. Several parasitic mites are also found on the new stonefly. This is the earliest known fossil evidence for mite parasitism in Plecoptera. This study examines a well-preserved piece of Eocene Baltic amber and discovers a new needle stonefly as the second known species of Baltileuctra which is parasitized by mites. New infor-mation is provided for Baltileuctra foraminis Chen, 2018a, and Euroleuctra gillesi Chen, 2018b, for morphological comparison.