Thalassaphorura (formerly Protaphorura) halophila is confined to the littoral zone. There are records from salt marshes, and under stones below high tide level. It is found together with Thalassaphorura debilis with which it has sometimes been confused (I have discovered several specimens of Thalassaphorura halophila 'hiding' under the name debilis in the NHML slide collection).
     Distinctive characters of
Thalassaphorura halophila include the complete absence of any trace of a furca, empodium about two thirds the length of the claw with a distinct lamella (Fig. 1), and post-antennal organ with about 25 simple vesicles (Fig. 2). There are two anal spines (Fig. 3). The arrangement of pseudocelli (PSO) on the hind margin of the head (Fig. 4) and abdomen (Figs. 5 and 6) is unusual. The typical PSO formula is 44/233/44454.

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Fig. 1 (above): Foot of the third leg of Thalassaphorura halophila collected from Cramond near Edinburgh in January 1937 by Bagnall.

Fig. 2 (above): Post-antennal organ (PAO) of Thalassaphorura halophila collected from Dalmeny near Edinburgh in May 1935 by Bagnall. There are four pseudocelli (1 to 4) adjacent to the PAO.

Fig. 4 (above): Posterior margin of the dorsal right side of the head of the same specimen of Thalassaphorura halophila shown in Fig. 2. There are four pseudocelli in an almost square arrangement. th1, first thoracic segment.

Fig. 3 (above): Posterior ventral side of a female specimen of Thalassaphorura halophila collected from Dalmeny near Edinburgh in May 1935 by Bagnall. There are two anal spines (*). fgp, female genital plate.

Fig. 5 (above): Dorsal side of the posterior abdomen of the same specimen of Thalassaphorura halophila shown in Fig. 3 (note different level of focus). The selected area is shown at higher magnification in Fig. 6.
Fig. 6 (below): There are five pseudocelli (1 to 5) on each side of the dorsal side of the fifth abdominal segment arranged in a 'crescent' shape.