Sminthurides signatus is moderately common and widespread. It is pinkish yellow in colour usually with some patches of violet or brown pigment on the body. Males reach 0.35 mm in length whereas females grow to 0.5 mm. In Sminthurides species, the male antenna is modified to grasp the female during mating and the long spine on the second antennal segment (ant2) is curved (Fig. 1). Females do not possess sub-anal appendages (SAA). In Sminthurides signatus, the fourth antennal segment in the female is divided into four subsegments (Fig. 2). The lamellae on the mucro are striated only on the upper side and there is no indentation on the ventral side near to the tip (Figs. 3). A tibiotarsal organ (tt organ) is present on the third leg and the empodium of the foot has a short filament that is of similar length to the claw (Fig. 4).
Fig. 1 (above): Antenna of a male Sminthurides signatus collected from Sacrewell Farm in January 1978 by Peter Lawrence.
Fig. 2 (above): Antenna of a female Sminthurides signatus collected from Sacrewell Farm in January 1978 by Peter Lawrence. The fourth antennal segment (ant4) is divided into four subsegments (1 to 4).
Fig. 3 (above): Distal furca of Sminthurides signatus collected from Sacrewell Farm in January 1978 by Peter Lawrence. There is no indentation on the ventral lamella of the mucro.
Fig. 4 (above): Foot and tibiotarsus (tt) of Sminthurides signatus collected from Sacrewell Farm in January 1978 by Peter Lawrence.
