Hapalocarcinus marsupialis Stimpson, 1859

Material examined. This species was recorded only by collected specimens because of its cryptic behavior. One ovigerous female (ICMyL MAZ 9306) from Ixtapa region; one ovigerous female (ICMyL MAZ 9080) from El Maguey.

Remarks. This species is considered symbiotic to corals and has a wide distribution in the Indo-Pacific, Central Pacific, and Eastern Pacific (see Pereyra 1998). In Mexican tropical waters out of the Gulf, there were no records, so our study closes a gap in its distribution and confirms the presence of H. marsupialis in the study area. The new range for Mexican waters is in the Huatulco region, about 1,700 km south of the previous data. This species occupies crevices in coral branches, so if is not easy to record by surveys, and our records were possible because of our collection of corals and picked out of the coral branches. Only ovigerous females were collected.