(079/MIsen) Micranurida sensillata (Gisin, 1953)
Micranurida sensillata is an extremely tiny and very rare soil-dwelling species which reaches only 0.4 mm in length. The only specimen in the NHM is a superbly mounted individual collected by Harold Gough from calcareous soil at Tarlton, Gloucestershire in 1974 (Fig. 1). This specimen clearly shows the teardrop-shaped sensory structures on ant4 (Fig. 2) and on each side of the second thoracic segment and fourth abdominal segment (Figs. 5, 6), and the peculiar sickle-shaped sensillum on the third segment of the antenna (Fig. 3). The post-antennal organ (PAO) has between 9 to 14 lobes (Fig. 4).
There is one other literature record by Curry (1969) from Ireland. Micranurida sensillata is white, blind and does not possess a furca. It must be much more common and widespread than records would indicate.
Fig. 1: Micranurida sensillata of 0.4 mm in length collected from Tarlton, Gloucestershire in March 1974 by Harold Gough.
Fig. 2: Teardrop-shaped sensory structure on the fourth antennal segment (ant4) of the same specimen of Micranurida sensillata shown in Fig. 1.
Fig. 3: Sickle-shaped sensillum on the third antennal segment of the same specimen of Micranurida sensillata shown in Fig. 1. The arrow points to the tip of the sensillum.
Fig. 4 (above): PAO with ten lobes of the same specimen of Micranurida sensillata shown in Fig. 1.
Fig. 5: 'Teardrop'-shaped sensilla on the dorsal side of the fourth abdominal segment of the same specimen of Micranurida sensillata shown in Fig. 1 (the dark cross is an artifact).
Fig. 6: 'Teardrop'-shaped sensilla shown in Fig. 5 at higher magnification.