Calcitrapessa leeana (Dall, 1890) An Unusual Muricid Gastropod

This species, known as a fossil in the Pleistocene of southern California, also lives today in the Gulf of California. Originally, this species was assigned to genus Calcitrapessa, but then for many years, workers began identifying it as genus Pteropurpura. It is now, however, known once again as Calcitrapessa leeana (Dall, 1890).

Many years ago, I was fortunate enough to find four specimens of this gastropod in an upper Pleistocene terrace deposit near the campus of Loyola College in Los Angeles. The specimens were easily freed from their sedimentary matrix. Sadly, this outcrop and surrounding area have since then been completely destroyed by “development."

According to the website WoRMS (2024), the classification of genus Calcitrapessa is:

Class Gastropod

Order Neogastropoda

Family Muricidae

Subfamily Ocenebrinae

Genus Calcitrapessa

Tuskes and Tuskes (2016) reported this species as Pteropurpura leeana and that it lives today off the west coast (Pacific side) of Baja California, primarily from Cedros Island south to Magdalena Bay. They reported also that these living specimens of P. leeana are only “infrequently collected,” usually by dredging (depths about 180 m) or by tangle nets. They also reported that the shells of leeana are the most divergent (i.e., different) when compared to other species belonging to the muricid family of gastropods. The northernmost known occurrence of a Recent (i.e., modern-day) specimen of P. leeana is Anacapa Island, and that specimen was found in 1941.

The largest fossil specimen that I found (illustrated below) is 6.5 cm [about 2.5 inches] in length and 4 cm [1.5 inches] in width. The tips of the stout spines on the last (body) whorl of this specimen are unfortunately missing, but otherwise preservation is excellent. 

Front and back, of a Pleistocene specimen of Calcitrapessa leeana from a now bull-dozed terrace deposit near Loyola College in Los Angeles. Length 6.5 cm [about 2.5 inches] and width 4 cm [1.5 inches].

Tuskes, P. and A. Tuskes. 2016. Native Pteropurpura of the eastern Pacific (Muricidae). The Festivus 48(4), pp. 211–220.