Nodifaunus gainesi DeVries 2019, sp. nov.
Creators: name: DeVries, Thomas J.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Pachychilidae
Nodifaunus
Nodifaunus gainesi

description: Nodifaunus gainesi sp. nov.
(Figure 4 (dd – ii))
Diagnosis
Early teleoconch whorls smooth; later whorls with tubercles or tuberculate axial ribs situated near posterior suture. Base smooth, separated from side of whorl by single spiral cord. Anterior canal short.
Description
Shell length to about 45 mm, high-spired, cerithiform, spire angle about 35° for early whorls, 15° for later whorls. Protoconch unknown. Teleoconch of nine or 10 slightly convex whorls; sutures impressed; sutures of early teleoconch whorls weakly canaliculate to turriculate. Spiral sculpture on earliest five or six whorls smooth; later whorls with spiral row of tubercles along posterior margin, present as blunt spines or developed as coarse prosocline, orthocline, or opisthocline axial ribs (variable orientation between and within individual shells) with blunt erect spines rising above posterior suture and extending partly or entirely to anterior suture; as many as 12 tubercles/axial ribs per whorl at first appearance, as few as eight on last whorl. No varices or ventrolateral varix. Faint spiral lines may be diagenetic artefacts. Growth lines orthocline to opisthocyrt. Base poorly preserved; steeply rounded, smooth, separated from side of whorl by spiral cord. Aperture rhombohedral; parietal area with broad callus, raised above body whorl; columella straight, thickened, without folds; anterior canal very short, slightly recurved abaxially. Outer lip mostly missing, posterior portion adjacent to suture extended abaxially with extension aligned with last subsutural tubercle; shallow posterior canal present.
Remarks
Nodifaunus gainesi sp. nov., with one spiral row of tubercles, differs from the early Eocene species, N. dimorphica, from the Talara Basin of northern Peru, which has a second row of nodes at the angled boundary of the base. Nodifaunus gainesi differs from N. propinqua and N. venusta, both also from the Talara Basin, which have one row of tubercles, but medially located. All three northern Peruvian species also have spiral cords or threads on the base and on the early whorls. The posterior suture-hugging single row of tubercles on specimens of N. gainesi most resembles the sculpture of specimens of Late Cretaceous N. nodosus, which also lack spiral cords, but the number of tubercles on the earliest nodose teleoconch whorls of N. gainesi (about 12) is double the number on the Late Cretaceous species.
Juvenile specimens of Nodifaunus gainesi have a widely flaring aperture with a thickened outer lip. Both a twisted anterior canal and posterior canal are present.
Etymology
‘ Gainesi ’, in recognition of Arthur G. Gaines, Oceanographer Emeritus, of the Woods Hole Oceanographic Institution, Woods Hole, MA, USA, and ocean sciences mentor to the author in the early 1970s.
Material
UWBM 107609, holotype, B8769 (type locality), L (42.4), W (19.1); remainder are paratypes: UWBM 107591, B8769, L (31.8), W (19.9); UWBM 107610, B8769, L (25.9), W (17.0); UWBM 107611, B8770, L (36.9), W (18.2); UWBM 107612, B8770, L 14.2, W 7.4; UWBM 107613, B8769, L 18.0, W 8.0; UWBM 107614, B8772, L (11.9), W 7.4; UWBM 107615, B8769, L (22.0), W (13.7); UWBM 107616, B8769, L (11.9), W (6.0); MUSM INV 263, B8769, L (33.0), W (15.8); MUSM INV 264, B8772, L (31.0), W (16.5); MUSM INV 265, B8769, L 15.9, W 8.1.
Occurrence
Lower Paleogene, Cuenca Member, Caballas Formation, East Pisco Basin, southern Peru.
description: Published as part of DeVries, Thomas J., 2019, Early Paleogene brackish-water molluscs from the Caballas Formation of the East Pisco Basin (Southern Peru), pp. 1533-1584 in Journal of Natural History 53 (25) on pages 1565-1566, DOI: 10.1080/00222933.2018.1524032, http://zenodo.org/record/3670229