Description of the second instar of Matus leechi Young (Coleoptera: Adephaga: Dytiscidae) is presented including a chaetotaxic and porotaxic analysis of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphi. Larvae of M. leechi are distinguished from those of other species of the genus Matus Aubé by (1) the non-pseudochelate pro-and mesothoracic tibiae, (2) the presence of spatulate lamellae clypeales, (3) the absence of secondary setae on the cephalic appendages, and (4) the very elongated urogomphi. It is postulated that the pseudochelate legs found in other species of Matus evolved within the genus Matus.