Ptocasius

According to Simon's original 1885 description^[2], Ptocasius is similar to the genus Hasarius but can be distinguished by several morphological characteristics. The cephalothorax is nearly identical to Hasarius but the eye area above is slightly longer, being barely one-quarter wider than long and either parallel or slightly wider posteriorly. Both anterior eye rows are convex. The eyes resemble those of Hasarius, but the posterior eyes of the second series are positioned wider apart from the posterior eyes than from the more distant anterior eyes.

The labial part is much more attenuated than in Hasarius. The chelicerae have an inferior margin furnished with two geminated teeth of very unequal size, with the second tooth being much smaller than the first. In males, the maxillae have an external posterior angular denticulation. The legs are similar to those of Hasarius, but the tibiae and metatarsi of legs I and II bear lateral spines on both sides, while tibiae I and II lack dorsal spines. Legs III and IV have a dorsal spine positioned in a smaller basin. The integument is clothed with simple hairs that are not squamiform.

Simon also noted that Ptocasius is closely related to the genus Cytaea but differs in having a shorter and more elevated cephalothorax, chelicerae with a superior margin provided with two teeth as in Hasarius (while Cytaea has four small teeth), two very unequal teeth on the inferior margin, and integuments furnished with simple pubescence rather than the squamous pubescence found in Cytaea.

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  P. weyersi from Thailand
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  P. weyersi from Thailand
• 
  P. yashodharae

As of August 2025^[update] it contains almost 70 described species, found only in Asia:^[1]