Key to the species of Pseudocaissa based on male genitalia

1. The valva is rounded and widened distally, densely covered with long hairs; the sacculus process is small......... P. apiata

- The valva is not distinctly broadened distally, covered with short hairs; the sacculus process is relatively larger........... 2

2. The juxta is broad, the upper margin without distinct lateral processes and lacking micro-spines; the phallus is stout, with one long, curved, strongly sclerotized sclerite and a spiny, large cornutus in the vesica......................... P. marvelosa

- The juxta is oval-shaped, the upper margin with a pair of distinct lateral processes densely covered with micro-spines; the phallus is slender, with only one long, slightly curved, weakly sclerotized sclerite and no cornutus in the vesica..... P. yutua