Duplacrorhynchus heyleni Artois & Schockaert, 1999

(Fig. 5 A–B)

New locality. iSimangaliso Wetland Park, Kosi Bay estuary, eastern shore of main lake, water plants, salinity 3– 4‰, December 15, 2009 (collected by Xander Combrink).

Known distribution. Tanzania, Zanzibar, widely distributed in mangrove sand flats (see Artois & Schockaert 1999).

Material. Several animals studied alive. One whole mount and three serially-sectioned individuals (HU, nos VII.3.43–VII.3.46).

Additional remarks. One individual measured on whole mount, considerably larger (1.4 mm) than those from Zanzibar (1 mm; see Artois & Schockaert 1999). Habitus and internal organisation almost identical to the original description, showing all diagnostic features of the taxon (Artois & Schockaert 1999), the only difference being the shorter length of the common genital atrium in comparison with that of specimens from Zanzibar. This observation could, however, be the result of the slightly-different orientation of the sections.

The South African specimens occur in a brackish habitat with very low salinity, whereas on Zanzibar they were only found in pure marine habitats. This seems to indicate that this species is euryhaline.