Meso-bathypelagic. Known to occur at depths between 300 and 1000 m after Matthews (1972, p.27).
The male descibed by Grice & Hulsemann (1967) as Euaugaptilus sp 2 could be this species. According to the authors the characteristics pointed out by Brodsky (1950) to distinguish his E. pseudaffinis from E. affinis (differences in the length of A1 and A2, and the structure of P5) seem insufficient to distinguish the two forms. No difference is obvious between Brodsky's and Sars' figure of the P5 of the female.
According to Brodsky (1967, p.381) E. pseudaffinis differs from the closely related E. affinis Sars in the presence of a long antennal ramus, the length of A1, and the structure of P5.
The presence of this species in the South Chinese Sea and in the NW Pacific is to be confirmed. W. Zhang confirms the presence of this species in the Seas of China (comm. pers., 2006).
Vives & Shmeleva ( 2007, p.187) report the presence of this species in the Indian Ocean, near Madagascar.

In ''affinis"" Group after Matthews (1972, p.64) {See remarks in Euaugaptilus genus}