Bulgaria is one of the smaller European countries, but it keeps great biological richness and diversity. It is generally believed that many thermophilic and drought-loving Mediterranean animals live in the southern regions of the country and on the Black Sea coast. This study is a part of a project researching faunal complexes along three large river valleys and the Black Sea coast, where a Mediterranean influence can be detected and which serve as main roads for the entry of thermophilic biota. The aim of this zoocenosis monitoring is to detect any changes in the composition of Bulgarian fauna. The first indication so far is the registration of Microlestes maurus cordatulus (Reitter, 1901) (Coleoptera: Carabidae). In April 2023, one male specimen of this subspecies was collected in an MSS trap, situated less than 20 km from the southernmost point of the Bulgarian coast: N of Ahtopol, N 42°06'33'', E 27°55'02'', 9 m a.s.l. Microlestes maurus Sturm, 1827 is a small (2.2 to 2.8 mm) black ground beetle with short, truncate elytra and bulging eyes with short temples. Its main identification characteristics are its genitals, as its penis is sclerotized and has a distinct apex with a hook-shaped denticle. In Bulgaria, this species is widespread in the plains and foothills. It is distributed in Europe (except in the north), Caucasus and Anterior Asia. According to the last edition of the Catalogue of the Palaearctic Coleoptera, the subspecies M. m. cordatulus is known only in Greece, Iran, Lebanon and Syria. The two subspecies of M. maurus clearly differ by the shape of their aedeagus, with that of M. m. cordatulus having a more elongated apex with a significantly less salient hook than that in the Bulgarian specimen. This new location suggests that M. m. cordatulus most certainly occurs on the Turkish Black Sea coast, too.