Abertella gualichensis Martínez et al., 2005

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 : 317-318

Abertella gualichensis Martínez et al., 2005

Figures 1 , 4 .

2005 Abertella gualichensis Martínez et al. : 1230–1232, figs. 2–3.

Diagnosis. Abertella with pronounced, marginally-directed, curved extensions of oral ambulacral plates joining proximal edges of first interambulacral postbasicoronal plates in posterior interambulacrum; posterior notch shallow but acute; paired interambulacra narrower, than in other Abertella , not narrowing near the ambitus. Type material studied. Holotype MACN-Pi 4714, paratypes MACN-Pi 4705, 4706, 4709. Description. See Martínez et al. (2005).

Occurrence. A. gualichensis is recorded only from the earliest middle Miocene of Salina del Gualicho, Río Negro Province, Argentina in the lower part of the Gran Bajo del Gualicho Formation ( Fig. 1 ).

Remarks. In the original description, A. gualichensis was distinguished from other Abertella largely by its broad but shallow posterior notch and its relatively narrow, non-alate test compared to other members of the genus. In addition, the separation of the oral interambulacral postbasicoronals from the basicoronal plates is less pronounced in A. gualichensis than in most other Abertella , with the exception of A. pirabensis , and the oral interambulacra of A. gualichensis do not widen and then markedly attenuate as they approach the ambitus.

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.