A new fossil lacewing (Ithonidae) from the Lower Cretaceous (Barremian-Aptian) Sinuiju Formation, Democratic People’s Republic of Korea
By: Kwang Sik So and Chol Guk Won
Summarized by Karla Rodriguez, a senior geology undergraduate major at the University of South Florida. She has always had an interest in hydrology and geophysics. She is currently a water quality scientific technician at the Southwest Florida Water Management District. Once she graduates, she is planning to continue work in the private sector of hydrogeology. Outside of work, she loves playing competitive video games, hoping to join tournaments in the future.
Hypothesis: The purpose of this research was to describe the first fossils of a net-wing insect, belonging to the lacewings group, found in the Democratic People’s Republic of Korea (DPRK) and establish these finds as an entirely new genus and species. This paper describes the morphology of Sinuijuala paekthoensis gen. et sp. nov. (gen. et. sp. nov. means new genus and species), and compares it to known, related lacewings.
Data used: Recovered Sinuijuala paekthoensis specimens were encapsulated in a portion of shale (fine-grained sedimentary rock deposited in aquatic environments) within the Lower Cretaceous Sinuiju Formation, located in Sinuiju City, North P’yŏngan province of DPRK. The lacewings were continuously buried by sediment, flattening the organisms. However, the burial allowed for unique preservation of wing features, head, and thorax (the middle part of the body). Wing venation provides one-of-a-kind patterns that can distinguish net-winged individuals, like lacewings, from other types of winged insects.
Methods: All recovered specimens were kept in the Paleontology laboratory at Kim II Sung University, which is in Pyongyang, DPRK. Microscope photographs of recovered Sinuijuala paekthoensis were taken with a Zeiss Discovery V20 microscope. Drawings of the images were created using Adobe Photoshop software. The number and positions of veins in the wing of the samples were measured using a microscope.
Results: This study provides the first documentation of lacewing fossils in DPRK. Researchers determined that Sinuijuala paekthoensis shares similarities with Ithonidae, a taxonomic family grouping of lacewings. Features like the lack of regular wing veining in part of the wing, and the branching of cross veins further in the middle anterior of the wing, as seen in Figure 1, are shared with the insect family, Ithonidae. Other fossils that have been found in the Sinuiju Formation are fossils of woody plants, indicating Sinuijuala was likely a woodland insect, similar to modern lacewings.
Why is this study important? The recovered specimens introduce a new genus and species of lacewings. This study was the first to find lacewings in DPRK, expanding the geographic range of these insects and increasing the total biodiversity of lacewings in the Early Cretaceous. The discovery of the net-winged insects here suggests the Sinuiju Formation may represent similar environments to other geological formations of the same age, such as the Yixian Formation in the People’s Republic of China, the Crato Formation in Northeast Brazil, and many others.
Broader Implications beyond this study: Finding new species of lacewings in DPRK shows that new discoveries can expand the biodiversity and biogeographic range of fossil insects, which are not commonly preserved in the fossil record. The compaction of the shale allowed for rare preservation of their delicate wings and unique features. Knowing more about how they were preserved, too, may help us identify other places where delicate organisms may have been encapsulated in sediment and fossilized. There are many more insect species waiting to be discovered, including but not limited to, lacewings!
Citation: So, & Won, C. G. (2022). A new fossil lacewing (Ithonidae) from the Lower Cretaceous (Barremian-Aptian) Sinuiju Formation, Democratic People’s Republic of Korea. Cretaceous Research, 138, 105288. https://doi.org/10.1016/j.cretres.2022.105288