Image of Periploma orbiculare Guppy 1882

Description:

An empty shell of the rare bivalve Periploma orbiculare Guppy, 1882 was observed and collected at University Beach, Corpus Christi Bay, Texas, on 2012-04-18. It is about 15.5 mm long, and one valve is broken, as sen on one of the photos. This is a very rare species in Texas. In fact, during research for our Encyclopedia of Texas Seashells book (Tunnell et al, 2010), we only found a single specimen deposited at the Houston Museum of Natural History. That shell is illustrated on page 337 of the book. It is interesting that the related species, Periploma margaritaceum is abundant locally, but P. orbiculare is so rare. Since finding this single specimen have have kept an eye on more specimens but so far this is the only one I have seen. Edit (2016): This species is found offshore in deeper waters in the Gulf of Mexico, and not in the shallow bays. There are at least a few records of this species collected live in research collections.