Arbacia ballenensis Courville & Mooi & Poulin & Saucede 2023, n. sp.

Arbacia ballenensis n. sp. Figures 2–4, table 1 Diagnosis. Arbacia with low, numerous interambulacral plates (N = 19 at TD = 20 mm); up to five subequal tubercles in interambulacral plates at the ambitus (TD = 20 mm); inner interambulacral tubercles close to the adoral plate margin; naked interambulacral areas elevated above adjacent ambulacra. Type material. Holotype specimen CASG 103360, housed in the Geology collections at the CAS, San Francisco, California, USA (Figs. 2A–D). The remaining specimens in lot CASG 91189, which includes 49 complete or partial tests, are designated as paratypes. Referred material. Sixty-two complete tests lacking articulated spines ranging from 6 to 20 mm TD, plus seven test fragments. In addition, there are several isolated spines in the poorly consolidated sandy sediments, some of which are also preserved within the peristome. Etymology. The name is derived from the type locality on Punta Ballena, as this species is so far known only from the Pliocene—Pleistocene of this point along Bahía San Rafael, close to San Francisquito (Baja California Norte, México). Stratigraphy. Late Pliocene to Early Pleistocene. Unnamed beds, middle part of the Punta Ballena fan (Johnson et al. 2017). Taphonomy. Specimens with complete tests (except for seven fragments), locally abundant in one specific layer, sometimes with attached balanomorph barnacles. It would appear from this, and the excellent condition of the surface details on the specimens that they were dead when buried, with little or no post-mortem transport (see below). Description. Test small, largest specimen barely reaching 20 mm TD (Fig. 2), test relatively low (height to diameter ratio 17 mm), decreasing in number slightly in small specimens to 12 or 13 plates in each interambulacrum (TD = 8 mm). Plates lowest above ambitus, height of plate constant on aboral surface (