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.

Zhi-Teng Chen [741208116@qq.com], School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang, 212004, China. Hong-Ling Liu [wstcczt@outlook.com] (corresponding author), Institute of Plant Protection, Sichuan Academy of Agricultural Sciences, Key Laboratory of Integrated Pest Management of Southwest Crops, Ministry of Agriculture, Chengdu, 610066, China.