Dallas (1851), Stål (1876) and Distant (1902) considered Cimex sulcatus Thunberg, 1783 as a synonym of Halys dentatus (Fabricius, 1775) based on the external morphology. Kirkaldy (1900) designated H. dentatus (Fabricius, “1803”) as a type species of the genus. Later he (Kirkaldy, 1909a) replaced this name, which turned out to be a junior primary homonym of Cimex dentatus De Geer, 1773, with the name H. sulcatus (Thunberg, 1783). Chopra (1974), accepting the synonymy established by Dallas (1851), described the species H. magnus. Ghauri (1988), having studied the types of H. dentatus, H. serriger and H. sulcatus, established the conspecificity of H. dentatus and H. serriger, and also placed H. magnus and H. qadrii in synonymy with H. sulcatus. Memon et al. (2002) resurrected H. dentatus from the synonymy with H. serriger. They proposed H. fabricii Memon, Ahmad & Perveen, 2002 as a new replacement name for H. dentatus. Salini (2019), having studied photos of habitus and the dissected male genitalia of the lectotype of H. dentatus synonymised H. fabricii with H. serriger. Gapon (2023) showed that the name H. sulcatus was applied to the taxon described as H. magnus, based on a variable character of the female terminalia, which has no diagnostic value. The type locality of H. sulcatus is in the southern regions of India, where no reliably identified specimens of H. magnus have been found. Therefore, H. sulcatus was recognised by Gapon (2023) as a senior synonym of H. serriger, and the name H. magnus was resurrected to the taxon distributed in the north of India.
There are no reliable records of H. sulcatus from the Palaearctic and it should be excluded from the Palaearctic fauna if H. magnus is confirmed to be a separate species.