Janthina pallida
W. Thompson, 1840
Description:
Dimensions range from 15 mm - 25 mm high and 14.5 mm - 22.1 mm wide.
Width to height ratio: 0.97:1 ~ 0.88:1
Shell: ; Spire low; small to moderately small. Exterior colour uniform very pale violet, palest of all Janthina species. About 6 whorls, inflated with rounded periphery, strongly and evenly convex, rounded, spirally engraved with striae, striae fine and wavy. Spire moderately tall. Suture deeply impressed. Columella arched, joins the outer lip in a tight curve and forming an anterior spout. Aperture rounded, circular-ovate, lip with central sinus which spans entire height of outer lip, most shallowly V-shaped of all living Janthina species [Beau, 2017]; outer lip widely flared outer lip.
Wilson [1983:281] notes that the central position of the lip sinus and anterior spout distinguish this species from J. janthina., Betti et al. [2017:491] discuss a large-scale stranding event of Janthina pallida along the Ligurian coast in May 2017, generated when offshore banks were driven inshore by sustained southerly winds. Recorded densities varied markedly between sites, from as low as 12.8 specimens m² to peaks of 2408 specimens m², with several localities exceeding 1000 specimens m² before a subsequent wind shift rapidly dispersed the banks offshore.
Distribution:
World wide in warm seas; Recorded from Mediterranean, Ireland[Thompson, 1840]; Morocco [Gofas et al., 2011:208]; South Africa;St Paul and Amsterdam Islands; Australia, Victoria, clockwise to Torres Strait [Beau, 2017:195]; Indonesia, Banda Sea [Adams & Reeve, 1858]; Bermuda to Brazil and entire Gulf of Mexico [Rosenberg et al., 2009:643]; common in Rio Grande du Sol in summer [Rios, 1985: 160].
Habitat:
Open sea, found on beaches after storms [Alf et al., 2020].
Etymology:
[latin] from pallidus = pale or faint.
Type Material:
Beu [2017:194] designated NHMUK 1951.3.14.4, a syntype of Janthina striolata A. Adams & Reeve, 1850, as the neotype of Janthina pallida Thompson, 1840, as no type material of J.pallida Thompson, 1840 was known to exist in the NHMUK.
Styntype [3]: NHM ZOO:1951.3.14.4-6 [as Ianthina striolata A. Adams & Reeve, 1850] - Type Locality: Pacific Ocean. [Natural History Museum, 2014]
Thompson, W. (1840). Plate II. Fig. 2.
Distribution
as listed in source literature
Thompson, W. (1840).
Plate II. Fig. 2.
pp: 96-97.
Adams, A. & Reeve, L. A. (1850a).
Shown in text as Ianthina striolata A. Adams & Reeve, 1850
Plate XI. Fig. 9.
pp: 54.
Shell subglobose-ovate, with a short spire, sutures slightly impressed, whorls rounded, spirally engraved with striae, striae fine and wavy, aperture circular-ovate; pale violet in colour
Reeve, L. A. (1858).
Plate IV. Fig. 20b.
Plate IV. Fig. 20a.
Translation: Shell globose, with a small spire; whorls flatly immersed at the sutures, then rounded, with decussate striations throughout; bluish, purplish-violet at the base; columella slightly reflexed; aperture broad and open.
Reeve, L. A. (1858).
Shown in text as Ianthina striolata A. Adams & Reeve, 1850
Plate V. Fig. 24a.
Plate V. Fig. 24b.
testá globosá, solidiusculá, spirá obtusè conicá, plus minus immersá, anfractibus converis, tumidiusculis, spiraliter peculiariter lineari-sulcatis, sulcis undulatis, valdè irregularibus; violas-cente-albá, medio subopacá, nitente; columella sublate reflexá, appressá; aperturá mediocri, haud sinuatá.
Tryon, G.W. (1887).
Shown in text as Ianthina globosa var. pallida Harvey
Plate 10. Fig. 15.
Plate 10. Fig. 16.
pp: 37.
Beu, A. G. (2017).
