Janthina exigua
Lamarck, 1816
Description:
Dimensions range from 6 mm - 20 mm high and 5 mm wide.
Width to height ratio: 0.83:1 ~ 0.25:1
Shell: globose, ovate-conical; thin, fragile; minute to small. Exterior colour violet, paler near the sutures.. About 5 whorls, rounded, with chevron-shaped growth striae following the shape of the lip sinus. Spire elevated, apex sharp. Suture impressed. Umbilicate: very narrow, partially covered by a thin columellar callus. Columella straight, smooth, slightly reflected. Aperture more than half of shell length, angular, somewhat ovate; outer lip thin, with a central, sharp, angular, v-shaped sinus. Operculum not present.
Distribution:
Worldwide, in tropical and temperate seas, including southern Australian states NSW to WA including Tasmania; New Zealand [Beechey, 2008]; Florida Keys to Brazil and entire Gulf of Mexico [Rosenberg et al, 2009:643]; State of Rio Grande du Sol, Brazil [Rios 1985:60], Tierra del Fuego Rochebrune & Mabille (1889, p. 45) record Janthina courcelli; R. & M. from Orange Bay, Tierra del Fuego.[Powell, 1960:142]; Hawaii, California, West coast Chile, Madeira, Reunion [Tryon, 1887]
Habitat:
pelagic, found washed up on beaches
Etymology:
[latin] from exiguus = small, slight or insignificant, in relation to the small size of the shell
Type Material:
Syntypes: Janthina exigua, 3 syntypes MHNG1094/80 now catalogued as MHNG-INVE51377 for Janthina exigua Lamarck, 1816 - Locality: without locality. [Beu, A. G., 2017]
Reeve, L. A. (1858). Plate V. Fig. 25b.
Distribution
as listed in source literature
Lamarck, J. B. P. A. de M. de (1816).
Plate 456. Fig. 2a-b.
Orbigny, A. D. d' (1841).
pp: 414.
Reeve, L. A. (1858).
Shown in text as Ianthina bifida Reeve, 1858
Plate V. Fig. 25a.
Shell turbinate, with an acuminately conical spire; whorls rounded, somewhat narrow, densely striated with concentric lamellae, the striae in the middle very obliquely sinuated; intensely violet; columella delicately reflexed, arched; aperture small, deeply notched.
Plate V. Fig. 25b.
Reeve, L. A. (1858).
Plate V. Fig. 21a.
Plate V. Fig. 21b.
Shell conical-turbinate, with an elevated spire, impressed sutures, and a sharp apex; whorls rounded, concentrically lamellate-wrinkled, with folds sinuous in the middle; deep violet, translucent; columella rather short, slightly reflexed; aperture small, notched in the middle.
Tryon, G.W. (1887).
Shown in text as Janthina capreolata Montrouzier, 1859, Janthina vinsoni Deshayes, 1863, Ianthina bifida Reeve, 1858
Plate 10. Fig. 18-19, 22.
Fig 18 Janthina capreolata Montrouzier, 1859
fig 29 Ianthina bifida Reeve, 1858
Plate 10. Fig. 17, 20-21.
fig 20 Janthina vinsoni Deshayes, 1863
pp: 37-38.
Macpherson, J.H. & Gabriel, C.J. (1962).
pp: 121. Fig. 146.
pp: 119.
Beechey, D. (2008).
pp: Janthina exigua. Fig. 1.
North Curl Curl Beach, NSW
Australian Museum C.362634
pp: Janthina exigua. Fig. 2.
North Curl Curl Beach, NSW
Australian Museum C.362634
Beu, A. G. (2017).
pp: 123. Plate 2. Fig. M.
GNS RM5626
Nukumaru Beach, Whanganui, New Zealand.
