Standardized Terminology for Description of Diverse Morphology of Late Jurassic Galatheoid Squat Lobsters (Decapoda: Anomura: Galatheoidea)

The Late Jurassic Ernstbrunn Formation of Ernstbrunn, Austria, has yielded both numerous and diverse new galatheoid (squat lobster) genera and species. To effectively describe these galatheoids, a standard terminology needs to be adopted for both the regions of the dorsal carapace and the ornamentation. In general, these galatheoids are much more complexly ornamented than modern galatheoids, and there is no existing terminology that is sufficient to describe them. Given the variety in both regions and grooves, a standard terminology will allow more accurate communication of species descriptions. One of the defining characteristics, reflecting the complex nature of the carapace, is the large number of grooves and regions. There are two main grooves: the circumgastric and the branchiocardiac. The circumgastric groove surrounds the gastric region and has two branches that define the epibranchial and hepatic regions. The branchiocardiac groove marks the anterior border of the branchial regions and the posterior border of the cardiac region. The anterior part of the galatheoid is composed of all regions anterior to the circumgastric groove (gastric, epibranchial, and hepatic regions). The posterior part of the galatheoid is composed of all regions posterior to the circumgastric groove. Many of the Jurassic galatheoids have well defined gastric, hepatic, epibranchial, and branchial regions. Most have moderately defined mesogastric and metagastric regions, and many have mesobranchial and intestinal regions present. Jurassic galatheoids all display similar styles of rounded protrusions as ornamentation. The size of the ornamentation is usually proportional to the size of the carapace. Establishment of a standardized terminology is essential in understanding the earliest known radiation of the Galatheoidea. Research supported by NSF grants EF-0531670 and INT-0313606 to Feldmann and Schweitzer.