Introduction
The Chasmocarcinidae are a goneplacoid crab family comprising 16 genera and over 50 species (extant taxa) with a tropical–subtropical distribution in the Indo-Pacific and West Atlantic. Chasmocarcinids are mostly known from marine subtidal environments to depths of over 2000 m. The subfamily Trogloplacinae are highly atypical among chasmocarcinids in having a freshwater life cycle (apart from one euryhaline species) and direct development. — John W. Short, 2026
Diagnosis
Carapace subrectangular to semicircular; anterolateral margins convex, unarmed or with up to 4 teeth or rounded lobes; legs relatively long and slender; male abdominal segments 3–5 fused; female genital opening sternal, male penes lying in closed or open grooves in sternite 8, first male gonopod moderately stout, second male gonopod noticeably shorter to slightly longer than first male gonopod. — John W. Short, 2026
