Iheringiella patagonensis (Desor in Agassiz & Desor, 1847 )

Mooi, Rich, Martínez, Sergio A., Del Río, Claudia J. & Ramos, Maria Inês Feijó, 2018, Late Oligocene - Miocene non-lunulate sand dollars of South America: Revision of abertellid taxa and descriptions of two new families, two new genera, and a new species, Zootaxa 4369 (3), pp. 301-326 : 322-323

Iheringiella patagonensis (Desor in Agassiz & Desor, 1847)

Figures 1 , 4 .

Diagnosis. As for the family and genus. We note, in addition, that I. patagonensis is the only South American scutelliform clypeasteroid in which test length and width are nearly equal (all other such species being significantly wider than long).

Occurrence. Arguably the most commonly encountered species of clypeasteroid in South America, I. patagonensis was evidently widespread during the late Oligocene and early Miocene in the southern Patagonian region of Argentina from the southern edge of Golfo San Jorge south to the northern edge of Tierra del Fuego ( Fig. 1 , inset). The recent discovery of specimens from the early Miocene Guadal Formation extends the known range of I. patagonensis westward to the Pampa Castillo region of southern Chile ( Frassinetti & Covacevich, 1999; Andre Wyss, pers. comm.).

Remarks. We recommend usage of the original spelling of the species name used in Desor (1847) and Agassiz & Desor (1847). Desor (1847) only listed names of taxa from Patagonia, without accompanying figures or descriptions, and these names are therefore here considered nomina nuda. In the same year, Desor (in Agassiz & Desor, 1847) provided cursory, but valid descriptions of two taxa, with locality information from the Patagonian region. Lacking figures, these descriptions have been the source of great confusion ever since. The type of one of these forms, Echinarachnius juliensis , from "Port Saint Julien" (Desor in Agassiz & Desor, 1847: 134), is known to exist in the collections of the Museum of Comparative Zoology, in Cambridge, Massachusetts. All known specimens presently identified as Iheringiella patagonensis compare favorably with this type. The types of the second form, Scutella patagonensis , reported to be from "Port Desire" (Desor in Agassiz & Desor, 1847: 135), have not been yet been found.

The situation is made more difficult by our inability to locate the original material upon which Lahille (1898) based his revision. Given the complex taxonomic history of the species involved, along with the provenance of the material, a full revision of the nomenclature is warranted and pending. For comparison with other taxa described herein, we provide a map of plate architecture of the oral surface of a typical specimen from the Puerto Santa Cruz region of Argentina. This specimen compares most favorably with the type of Scutella juliensis . However, as is common for all such material, it is identified as Iheringiella patagonensis until the situation concerning the relationship between the types of S. juliensis and I. patagonensis can be resolved. What seems clear from the present evidence is that these two named entities are congeneric. Iheringiella does not have any indication of a posterior notch, making it the only described species of South American scutelliform to lack this feature.

Figures

FIGURE 1. Localities for taxa discussed in the text. Inset at lower left centers on the Santa Cruz region of Patagonia. Numbered occurrences correspond to unequivocal Iheringiella patagonensis localities (inside boxed region in main map): 1. Pampa Castillo, Chile (Andre Wyss, pers. comm.); 2. Cañadón El Lobo, Santa Cruz, Argentina (CPBA 16493-95); 3. Oven Point/Sholl's Tomb, Santa Cruz, Argentina (Ortmann 1902), Punta Cuevas, Santa Cruz, Argentina (MACN 4586 and Cuitiño 2011), Playa La Mina, Santa Cruz, Argentina (Cuitiño 2011); 4. Meseta Chica, Bajo de San Julián, Santa Cruz, Argentina (MACN 5144 and Cuitiño 2011); 5. Upper Rio Chalia, Santa Cruz, Argentina (Ortmann 1902); 6. Puerto Santa Cruz, Santa Cruz, Argentina (ROM 5433M, 5468M, 5469M); 7. Sector Flamenco, Tierra del Fuego, Chile (Larrain 1984)—reported to be from Eocene strata, but this is questionable (Mooi et al. 2000).

FIGURE 4. Comparison of oral plate architecture of Iheringiella patagonensis (Desor, 1847) (based on ROM 5433M), Abertella gualichensisMartínez et al., 2005(based on the holotype,MACN-Pi 4706),Abertella pirabensis(Marchesini Santos, 1958) (reconstruction based on the holotype and only known specimen, DNPM 4493, details of interambulcrum 2 inferred by comparison with interambulacrum 4, and of ambulacrum V by comparison with ambulacrum I), and Placatenella complanata (Brito, 1981) (based on the holotype, MNRJ 5460-I, as well as MNRJ 5536-I, MPEG 886-I, MPEG 2405-I). Food grooves indicated by dotted lines, peristome and periproctin solid black, interambulacra shaded, scale bars 10 mm in length.