Sphaeroma walkeri Stebbing, 1905

Material Examined: CNCR­20403; number of specimens: 2; SM station; collection date: 16/10/98.

Type locality: Sri Lanka

Distribution: This species occurs on eastern Florida (Camp et al., 1977; Nelson & Demetriades, 1992); the Gulf of Mexico (Kensley & Schotte, 1989; Nelson & Demetriades, 1992); Puerto Rico, Brazil (Nelson & Demetriades, 1992); the California coast (Carlton & Iverson, 1981), Hawaii (Nelson & Demetriades, 1992); Hong Kong (Mak et al. 1985); Australia, India, Sri Lanka, the Red Sea and Africa (Nelson & Demetriades, 1992; Kensley & Schotte, 2000).

Range extension: In the Gulf of Mexico, Sphaeroma walkeri has been recorded from the western Florida and Texas coasts (Kensley & Schotte, 1989; Nelson & Demetriades, 1992). The presence of S. walkeri at SM inlet, extends its geographic distribution to Tamaulipas State, Mexico.

Remarks: This species has mangrove roots and dead trees as preferred habitats (Kensley et al. 1995), but may also be associated with colonies of sabellariid worms (Nelson & Demetriades, 1992). It occurs in marine, shallow, intertidal warm waters and probably it is limited to a pantropical distribution (Kensley & Schotte, 1989, 2000).

The salinity and temperature ranges measured at site were 24 to 26 %o and 27 to 28 °C, respectively.