In Sminthuridesspecies, the male antenna is modified to grasp the female during mating and the long spine on the second antennal segment (ant2) is curved. Females do not possess sub-anal appendages (SAA). The distinguishing feature of Sminthurides cruciatus is the presence of a prominent cross-shaped mark on the dorsal side of the body. The morphology is very similar to the common Sminthurides aquaticus and Sminthurides malmgreni although the female antennae are apparently shorter in Sminthurides cruciatus than in these two species.
Sminthurides cruciatushas only been recorded once from England. Jackson (1928) reported finding a single specimen (sex not stated) on the surface of a puddle at Wicken Fen (the single green dot on the map). There are no specimens in the NHML slide collection.