Cortana carvalhoi ( Brito, 1967 ) Salvador & Simone, 2013

Salvador, Rodrigo Brincalepe & Simone, Luiz Ricardo Lopes De, 2013, Taxonomic Revision Of The Fossil Pulmonate Mollusks Of Itaboraí Basin (Paleocene), Brazil, Papéis Avulsos de Zoologia 53 (2), pp. 5-46 : 5-46

Cortana carvalhoi ( Brito, 1967) comb. nov.

( Figs. 40-42 )

Bulimulus carvalhoi Brito, 1967: 18 (pl. 2, fig. 4-6); Palma & Brito, 1974: 394 (pl. 1, fig. 2); Breure, 1979: 137; Simone & Mezzalira, 1994: 50 (pl. 14, fig. 418).

Itaborahia carvalhoi : Bergqvist et al., 2006: 58 (fig. 66).

Holotype: DGM 4995 -I (examined; Figs. 40-42 ).

Paratype: DGM 4996 -I (1 specimen, examined) .

Type Locality: Limestones of Parque Paleontológico de São José de Itaboraí, Rio de Janeiro, Brazil. Park’s center coordinates: 22°50’20”S, 42°52’30”W .

Geographic and stratigraphic occurrence: Known only from the type locality: Sequence S1 ( Medeiros & Bergqvist, 1999; Bergqvist et al., 2006).

Age : Tertiary, Middle Paleocene. Etymology: Species dedicated to its collector, Julio S. Carvalho (Divisão de Geologia e Mineralogia do Departamento Nacional de Produção Mineral, DNPM, Rio de Janeiro, Brazil).

Diagnosis: Shell fusiform. Spire apex acuminated, with straight outline. Profile of whorls flat. Peristome greatly reflected, with exception of upper palatal region. Aperture oval, elongated anteroposteriorly, orthocline; median palatal tooth, columellar lamella and channel-like structure immediately above the lamella. Umbilicus imperforated.

Re-Description: Shell large, fusiform. Greatest width on body whorl; width ~2/5 shell length. Spire angle ~45°. Spire apex acuminated, with straight outline. Profile of whorls flat. Suture well-marked, linear, oblique (diagonal) to columellar axis, Protoconch apparently smooth; transition to teleoconch unclear. Teleoconch smooth, except for growth lines. Aperture medium-sized, oval elongated anteroposteriorly (width ~½ height), orthocline, occluded by columellar lamella and palatal tooth in its median portion; aperture ~2/5 shell length. Peristome greatly reflected, with exception of upper palatal region; incomplete (absent in parietal region). Aperture with columellar lamella extending itself towards interior and a median palatal tooth. Aperture with channel-like structure immediately above columellar lamella (makes columella seem twisted). Body whorl ~½ shell length. Umbilicus imperforated.

Measures (in mm): Holotype: 8 whorls; H = 30.5; D = 12.0; S = 17.9; h = 13.0; d = 6.1. Paratype: D = 9.1.

Examined material: Types.

Discussion: This species was originally classified in the genus Bulimulus by Brito (1967) and was posteriorly transferred to Itaborahia by Bergqvist et al. (2006). Clearly, this species differs greatly from species of both genera and from all other orthalicids (mainly due to its unique aperture) and was thus reallocated in the new genus Cortana , as stated above.

As explained in the discussion above for the genus, C. carvalhoi ’s aperture shows some similarities to the genera Eudolichotis and Otostomus . However, the aperture still differs greatly from both due to the dentition and the channel-like structure. The aperture shows a partial occlusion in its median region due to the palatal tooth and the columellar lamella. Apertural occlusions by strong structures such as seen in C. carvalhoi are typical barriers that protect against predators that attack through the aperture ( Solem, 1972; Goodfriend, 1986; Stanley, 1988; Vermeij, 1993; Gittenberger, 1996; Barker & Efford, 2004).

Remarks: The holotype shows markings similar to a sculpture pattern on part of the body whorl ( Fig. 40 ). However, this does not seem to be a natural pattern; instead, it seems to have been caused during fossil diagenesis.

Figures

FIGURES 32-42: 32-33. Temesa magalhaesi (DGM 4997-I) with broken aperture, showing the parietal lamella (pt). 34-35. Cecilioides sommeri (MNRJ 5016-I; holotype); shell length 2.5 mm. 36. Bulimulus fazendicus (AMNH 24243; holotype); shell length 16.5 mm. 37. B. fazendicus (AMNH 24242; paratype); shell length 16.5 mm. 38-39. Bulimulus trindadeae (MNRJ 5022-I; holotype); shell length 9.5 mm. 40-42. Cortana carvalhoi (DGM 4995-I; holotype); shell length 30.5 mm.