This study reports the first Korean records of the genus Acerocnema Becker, 1894, with one new species, Acerocnema saurischia sp. nov., and one newly recorded species, A. flavifrons. A key to the Korean Scathophagidae is provided with morphological diagnosis and images of habitus and male genitalia structures. To assist in species identification, mitochondrial cytochrome c oxidase subunit I (COI) gene sequences were obtained from all specimens to conduct DNA barcoding.

Scathophagidae, commonly known as dung flies, is a small dipteran family of Muscoidea and is the sister group of Anthomyiidae. Currently, there are 373 described species distributed across 47 genera worldwide. Scathophagidae is subdivided into two subfamilies, Scathophaginae and Delininae. Notably, Delininae is characterized by tergite 6 short, bare, and firmly fused with syntergosternite 7+8. Delininae includes five genera and one uncertain genus with around 26 species described to date. Taxonomic instability within Delininae has been raised by notable inconsistencies, particularly evident in the classification of genera of Americina Malloch, 1923, Parallelomma Becker, 1894, and Leptopa Zetterstedt, 1838. These disparities necessitate a systematic reevaluation to rectify taxonomic uncertainties, acknowledging the nuanced variations introduced by different taxonomists. To address these taxonomic conundrums within Delininae, molecular approaches were employed, using three mitochondrial genes (16S, Cytb, COIb) and three nuclear genes (28S, Ef1a, Pol II). Phylogenetic analysis was conducted by maximum likelihood and Bayesian methods to elucidate the comprehensive phylogenetic relationships within Delininae. Particularly, this study includes previously unexplored genera, namely Neochirosia Malloch, 1917 and Micropselapha Becker, 1894, and uncertain genus Synchysa Vockeroth, 1987, encompassing all genera in Delininae. The incorporation of all taxa contributes to a more thorough understanding of the evolutionary history within Scathophagidae, shedding light on previously overlooked aspects of its phylogenetic landscape.