Background

The diversity of irregular echinoids along the Pacific coast of Mexico is still not well known. This group has developed a selection of a restricted substrate; in addition, they are morphologically adapted to bury themselves in sediment that makes them difficult to locate in the field.

Goals

To prepare a checklist of species of irregular echinoids including new records of the Cassiduloida, Clypeasteroida, Holasteroida, and Spatangoida orders found along the coasts of Nayarit, Jalisco, and Colima.

Methods

Organisms were collected through various sampling operations undertaken between December 2013 and August 2017, in subtidal zones with Scuba diving gear (up to 10 m) and in sandy beaches using manual collection. In addition, we carried out a review of bibliographic sources and scientific collections.

Results

Eighteen species from nine families and four orders of irregular urchins were registered for the coasts of Nayarit, Jalisco, and Colima. For Nayarit there are nine species and the species Encope micropora was registered for the first time in Playa Novillero. Ten species were recorded in Jalisco and 14 species in Colima, which for both states established new records for the species Rhyncholampas pacificus, Agassizia scrobiculata, Brissus obesus, Metalia spatagus, and Plagiobrissus pacificus.

Conclusions

The literature review, complemented with field sampling, helped increase the diversity of species of irregular sea urchins in the central Mexican Pacific region. Determining the diversity of these species will make it possible to propose future studies on their ecology, in order to specify their ecological role in coastal ecosystems and their potential use for the conservation of marine communities.