Gibberula vignali Dautzenberg & Fischer 1896
Creators: name: Sacchetti, Claudia
name: Landau, Bernard
name: Ávila, Sérgio P.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Neogastropoda
Cystiscidae
Gibberula
Gibberula vignali

description: Gibberula vignali Dautzenberg & Fischer, 1896
Plate 4 G 1 -G 3
* Gibberula vignali Dautzenberg & Fischer 1896: 433, pl. 15, fig. 17.
? Gibberula lazaroi Contreras 1992: 44, 45, unnumbered fig.
Gibberula vignali (Dautzenberg & Fischer, 1896) — Martins 2009: 64, fig. 198.
Santa Maria material examined. Maximum height 2.8 mm, width 1.6 mm. DBUA-F 1044-1 (1), Pedra-que-pica, Santa Maria Island, Azores, Touril Complex, Lower Pliocene.
Description. Shell small for genus, solid, cylindrical-ovate, with low spire. Protoconch covered by callus. Teleoconch of about two whorls, suture superficial. Last whorl more than 95% total height, convex, maximum diameter situated just above mid-height, not constricted at base. Surface smooth and glossy. Aperture narrow, elongate, weakly curved, slightly wider abapically. Outer lip moderately thickened, not extending adapically to level of suture, abapically extending just beyond tip of siphonal fasciole, smooth within; siphonal canal very short, open, shallowly notched. Columella weakly convex, bearing about six plications on the lowe half, the adapical two subobsolete, abapical four plications more strongly developed, strengthening abapically. Two abapical plications extend externally over columella. Parietal callus weakly developed, narrowly expanded over venter. Siphonal fasciole not delimited.
Discussion. Gibberula vignali (Dautzenberg & Fischer, 1896), is characterised by small sized shells for the genus, low spire, outer lip that slopes steeply downwards from the point of insertion, and is not alate adapically, the inner lip bearing small, weak denticles and columella seven folds, increasing in strength abapically. The last two folds do not extent over the venter as they do in some of its congeners. Contreras (1992) described G. lazaroi from present-day Pico and Terceira Islands, Azores. In his discussion he did not compare his new taxon to G. vignali. Comparing the illustration of the holotype (Contreras 1992: 45, unnumbered figure) with that of G. vignali (Dautzenberg & Fischer 1896: pl. 15, fig. 17) we fail to see any significant differences between the two, which are both 2.0 mm in height. On the WoRMs database is a photograph of a specimen identified as G. vignali from Morocco. This specimen is squatter with a more alate outer lip and fewer columellar folds than the holotype, and we are unsure if it represents the same species. We have not seen the holotypes of these two species and therefore refrain from synonymising them.
Several small, eastern Atlantic Gibberula species need to be compared. Gibberula lazaroi is closely similar to G. jansseni Van Aartsen, Menkhorst & Gittenberger, 1984, from the Bay of Algeciras, Spain, but differs in being slightly more globose and having more numerous columellar folds, which are coarser. Gibberula hernandezi Contreras & Talavera, 1988, from the Madeira, Selvagens and the Canary Islands, is immediately separated by a taller spire with two sutures visible and the anterior columellar folds that extend over the venter.
Gibberula vignali, together with Alvania mediolittoralis Gofas, 1989, and A. sleursi (Amati, 1987) form part of the endemic Azorean fauna that was already present in the early Pliocene.
Distribution. Lower Pliocene: Atlantic, Santa Maria Island, Azores (this paper). Present-day: Atlantic, Azores (Dautzenberg & Fischer 1896;? Contreras 1992; Martins et al. 2009).
description: Published as part of Sacchetti, Claudia, Landau, Bernard & Ávila, Sérgio P., 2023, The Lower Pliocene marine gastropods of Santa Maria Island, Azores: Taxonomy and palaeobiogeographic implications, pp. 1-150 in Zootaxa 5295 (1) on pages 64-65, DOI: 10.11646/zootaxa.5295.1.1, http://zenodo.org/record/7965273