Evolution of Janthina and Recluzia (Mollusca: Gastropoda: Epitoniidae)
Author
Beu, Alan G.
text
Records of the Australian Museum
2017
Rec. Aust. Mus.
2017-08-23
69
3
119
222
http://dx.doi.org/10.3853/j.2201-4349.69.2017.1666
journal article
10.3853/j.2201-4349.69.2017.1666
d63960a1-e0c5-4b97-8e7d-f8be80d376d6
2201-4349
4677010
Janthina pallida
Thompson, 1840
Figs 2K–L
,
5B
Janthina pallida
Thompson, 1840: 96
, pl. 2, fig. 2 (under “
J. nitens
?”, name attributed to Harvey; tentatively a new species).
Janthina pallida
Harvey.
–
Thorpe, 1844: 152
;
Küster, 1868: 5
, pl. 1, fig. 5;
Monterosato, 1878: 95
;
Locard, 1898: 2
;
Dall, 1908: 318
.
Ianthina striolata
A.Adams & Reeve, 1850: 54
, pl. 11, fig. 9; H. Adams & A. Adams, 1854: 87;
Reeve, 1858
: pl. 5, figs 24a–b; Hedley, 1900: 141; Pritchard & Gatliff, 1900: 141; Macpherson & Chapple, 1951: 124;
Cotton, 1959: 376
.
Ianthina pallida
Harvey.
–
Forbes & Hanley, 1853: 553, pl. 69, figs 10–11; H. Adams & A. Adams, 1854: 87;
Reeve, 1858
: pl. 4, figs 20a–b;
Benson, 1860: 412
; G. B. Sowerby II, 1882: 51, pl. 444, figs 19–20.
Table 8
. Dimensions of
Janthina exigua
.
Janthina (Amethistina) pallida
Harway
[sic].
–
Mörch, 1860: 281
.
| locality height |
diam. |
H/D |
| GNS RM5311, Piha Beach, W Auckland, NZ |
19.5 |
16.7 |
1.17 |
| GNS RM5311, Pih a Beach |
18.3 |
16.1 |
1.14 |
| GNS RM5311, Piha Beach |
16.7 |
15.7 |
1.06 |
| GNS RM5626, Nukumaru Beach, Whanganui, NZ |
16.9 |
14.9 |
1.13 |
| GNS RM5626, Nukumaru Beach |
16.0 |
13.6 |
1.18 |
| GNS RM5626, Nukumaru Beach |
15.9 |
13.9 |
1.14 |
| GNS RM5626, Nukumaru Beach |
16.2 |
14.3 |
1.13 |
| GNS RM5626, Nukumaru Beach |
17.2 |
14.1 |
1.22 |
| NMNZ M277699, Karioitahi Beach, Waiuku, NZ |
20.7 |
17.6 |
1.18 |
| NMNZ M277699, Karioitahi Beach |
20.8 |
18.8 |
1.11 |
| NMNZ M277699, Karioitahi Beach |
20.3 |
17.8 |
1.14 |
| NMNZ M277699, Karioitahi Beach |
19.7 |
18.3 |
1.08 |
| NMNZ M277699, Karioitahi Beach |
22.0 |
17.2 |
1.28 |
| NMNZ M214377, Raoul I, Kermadec Is. |
18.1 |
15.1 |
1.20 |
Janthina (Amethistina) striolata
Adams & Reeve.
–
Mörch, 1860: 282
.
Amethistina pallida
(Harvey)
.
–
Monterosato, 1884: 105
.
Janthina pallida
(Harvey Mss) Thompson.
–Bucquoy
et al
., 1886: 435, text-fig. 7.
Ianthina globosa
var.
pallida
Harvey.
–
Tryon, 1887: 37
, pl. 10, figs 15–16.
Janthina (Amethistina) pallida
Harvey.
–
Thiele, 1929
, p. 225
;
Priolo, 1959: 186
.
Ianthina pallida
Thompson.
–
Laursen, 1953: 31
, figs 36–39; Macpherson & Gabriel, 1962: 119.
Ianthina globosa
Swainson.
–
Morton, 1954: 167
(in part
J. pallida
, misidentified as
J. globosa
).
Janthina pallida
(Harvey) Thompson.
–
Pasteur-Humbert, 1962: 53
, fig. 75.
Janthina pallida
Thompson.
–
Bennett, 1966: 47
, pl. 10, figs 2–3; Fretter & Graham, 1982: 393, fig. 280; Kilburn & Rippey, 1982: 79; Wells & Bryce, 1986: 60, fig. 154;
Giannuzzi-Savelli
et al
., 1999: 54–57
, figs 96a–101;
Redfern, 2001: 76
, pl. 36, fig. 317; Ardovini & Cossignani, 2004: 28, 136;
Robertson, 2007a: 5
, fig. 4;
Luque, 2011: 209
, text-fig.;
Hernández
et al
., 2011: 98
, figs 30J–K.
Violetta pallida
(Thompson)
.
–
Kuroda
et al
., 1971: 246
, pl. 62, fig. 15.
Janthina (Violetta) pallida
Thompson.
–
Abbott, 1974: 113
, col. pl. 3, fig. 1180;
Higo
et al.,
1999: 174
.
Janthina (Violeta)
[sic]
pallida
Thompson.
–
Rios 1994: 102
, pl. 33, fig. 415.
Janthina (Amethistina) pallida
Thompson.
–
Okutani, 2000: 319
, pl. 158, fig. 3.
Janthina pallida
Harvey
in Thompson.–
Poppe, 2008: 722
, pl. 306, fig. 3.
Janthina exigua
Lamarck.
–
Severns 2011: 198
, lower fig (misidentification).
Type material
.
Janthina pallida
, no type material in
NHMUK
, location of any type material not known; from Milton Malbay, County
Clare
,
Ireland
.
Thorpe (1844: 152)
also stated the locality as “
Clare
”.
Janthina striolata
, three
syntypes
NHMUK
1951.3.14.4–6, from “Pacific Ocean”,
ex
Cuming collection. It would be preferable to use a specimen that has been included in a molecular study as the
neotype
for
J. pallida
, as for all other species, but this species has not been studied by this means. A. Adams & Reeve’s (1850: 54, pl. 11, fig. 9) and
Reeve’s (1858
: pl. 4, figs 20a–b) illustrated
syntype
of
J. striolata
,
NHMUK
1951.3.14.4, is here designated the
neotype
of
Janthina pallida
Thompson, 1840
. The three
syntypes
of
Janthina striolata
are unusual specimens with weak, irregularly spaced, insignificant spiral threads around the last whorl, but are otherwise typical of
J. pallida
. Because of the cosmopolitan distribution of this as well as all other
Janthina
species and the very wide locality stated for
J. striolata
, the type locality of these names is not considered to be an important consideration for a
neotype
designation, and the designation of this
neotype
is necessary for the stabilization of the name
Janthina pallida
.
Other material examined
. Present-day samples from
Australia
and
New Zealand
:
Australia
:
Northern Territory
:
Cape Wessel (
WAM
); E side Cape Wessel I., Arnhem Land (
AMS
C77883
); Port Darwin (
AMS
C13905
).
Western Australia
:
Cable Beach, Broome (
NMV
); City Beach, Perth (
AMS
); False Bay (
AMS
); King George Sound (many,
SAMA
); Cheyne Beach (
WAM
); Peaceful Bay,Bow Bridge (
WAM
); Bunbury (
AMS
);Windy Harbour, Cape D’Entrecasteaux (
GNS
WM15256, 1).
South Australia
:
Port Lincoln (
WAM
);
Victoria
:
Portland (
SAMA
;
NMV
); Mordialloc (
NMV
).
Queensland
:
Torres Strait (
AMS
).
Distribution
. The writer is not aware of fossils of
Janthina pallida
.
Laursen (1953: 33)
recorded
Janthina pallida
from “the three oceans, but north of the equator … where the temperature does not drop below 15°C”. This peculiar distribution, in which inter-ocean connections would not be possible, is proved incorrect by
Benson’s (1860)
much earlier records of
J. pallida
collected from the
Malcolm
near
Tristan da Cunha
in the South Atlantic (
30°S
18°W
–
33°S
10°W
) and NE of St Paul and Amsterdam Islands, as well as midway between Natal and
Western Australia
(
33°S
81°E
–
30°S
83°E
) in the southern Indian Ocean.
Bennett (1966: 47
, pl. 10, figs 2–3) illustrated specimens collected alive in the North Pacific (
31°06'N
130°06'W
; and “in North Pacific waters”) during a cruise c.
500 km
west of California,
31°N
125–
140°W
.Australian beach records of
J. pallida
also disprove Laursen’s statement. Although
J. pallida
has never been recorded from much of the coastline of
Australia
by Hedley, Iredale or other major Australian authors, museum collections show that it occurs sporadically around the southern, western and northern coasts (clockwise, from western
Victoria
to Torres Strait). It is relatively common in southern
Western Australia
, and specimens have been seen from
South Africa
(
Table 9
)—a pattern suggesting transport from the Atlantic via
South Africa
in the Antarctic Circumpolar Current. Kilburn & Rippey (1982: 79) also recorded specimens from
South Africa
. However, the writer is not aware of records from
New Zealand
, eastern
Australia
, or
Norfolk Island
, Lord Howe Island and the Kermadec Islands. It is one of the more northward-ranging species in the Atlantic, occurring in southern Britain, and seems to have a somewhat sporadic occurrence throughout the world tropical and warm-temperate ocean.
Savilov (1969: 402)
also noted that the
Vityaz
observed
J. pallida
only in the North Pacific. Samples were obtained at only 12 stations in the northern subtropical circulation, mainly in areas contiguous with the Kuroshio Current. However, it is evidently common in the Mediterranean (
Figs 4A
,
5B
);
280 specimens
were reported by
Palazzi (1979)
cast ashore on beaches in Sicily.
Dimensions
. See
Table 9
.
Diagnosis
. Moderate-sized (H to c.
30 mm
), spire moderately tall, whorls strongly and evenly convex, suture deeply impressed; surface lightly polished, without obvious sculpture other than fine spiral threads on a few specimens. Sinus occupying entire height of outer lip, most shallowly V-shaped of all living
Janthina
species; apex in centre of lip. Anterior end of aperture evenly semicircular; many specimens with widely flared outer lip; central columella curved forwards (abaperturally). Almost uniform very pale violet, slightly paler dorsally; palest of all
Janthina
species. Lays ovate-triangular egg capsules on underside of float.
Remarks
.
Thompson (1840: 96
, pl. 2, fig. 2) published the name
Janthina pallida
in the synonymy of “
J. nitens
?”, and stated that the name
J. pallida
had been suggested verbally by his friend Harvey, who collected the specimens.
Thompson (1840: 96)
stated that it was most similar to
Ianthina nitens
Menke
, as described and illustrated by Philippi in “Enumeration molluscorum Siciliae” (i.e.,
Janthina globosa
), but differs in the columella being curved, instead of being straight, so that the anterior end of the aperture is rounded, and “ … the colour … is very different”.
Thompson’s (1840
: pl. 2, fig. 2) drawing is an excellent one of
J. pallida
of all later authors, emphasising the evenly subcircular aperture. Many authors before 1961, beginning with
Thorpe (1844: 152)
, have treated
J. pallida
as the valid name for this species. Therefore, the name
J. pallida
is conserved under ICZN Article 11.6.1. Following Article 11.6.1 the name should be attributed to
Thompson (1840: 96)
, “its first publication as a synonym”. The name has been attributed correctly by many later authors. Many others have attributed it to Harvey, but the name definitely was made available by
Thompson (1840)
according to Article 11.6.1. The name
J. pallida
was attributed to Harvey in 13 references listed by
Priolo (1959: 186–187)
; only two of those Priolo cited attributed it to Thompson.
Thorpe (1844: 152)
provided a slightly muddled attribution of the name to “Thompson’s Annals of Nat. Hist. 5. p. 96. t. 2. f. 2.”, and was followed by
Dall (1908: 318)
.
Dall (1908)
provided a publication date of 1817, even though Forbes & Hanley (1853: 553) provided the correct reference, despite attributing the name to Harvey. The name
Janthina pallida
was not published in 1817 (Sherborn, 1922–1933) and the page and figure numbers cited by both Thorpe and Dall are the same as for
Thompson (1840)
, so their references were in error. Several other authors have published muddled references to this name, not having seen
Thompson’s (1840)
paper.
Table 9
. Dimensions of
Janthina pallida
.
| locality height |
diam. |
H/D |
|
Janthina striolata
syntype, neotype of
J. pallida
22.6
|
21.1 |
1.07 |
|
Janthina striolata
syntype, NHMUK1951.3.14.5 24.0
|
22.2 |
1.08 |
| GNS WM15256, Windy Harbour, S Western Australia 16.5 |
14.5 |
1.14 |
| GNS WM19277, Muizenberg, False Bay, South Africa 18.6 |
16.2 |
1.15 |
Janthina pallida
consistently is smaller than the largest specimens of
J. globosa
, but is otherwise very similar in most characters. The illustration by Ardovini & Cossignani (2004: 136) shows an unusually tall, narrow specimen. The obvious difference from
J. globosa
is that it lacks the small, angular, anterior extension of the columellar margin of the aperture of
J. globosa
, and instead the anterior end of the aperture is evenly and regularly curved in
J. pallida
. The outer lip sinus also is very shallow, considerably shallower than in all other living
Janthina
species. A unique character is that the central area of the columella is quite strongly convex, curving towards the anterior (abaperturally). Many specimens also have the outer lip quite broadly flared, or reflexed, a further unique character. Most specimens are also a much paler violet colour than all other
Janthina
species, fading almost to white on the sutural ramp of some specimens. Some specimens also have a weak spiral ridge or groove formed as the trace of the apex of the sinus in the outer lip, showing as a low spiral ridge on spire whorls of about 20% of specimens (as in
Laursen, 1953
: fig. 36), but this is an individual character. The radular teeth (
Laursen, 1953
: fig. 39) are much the shortest and most strongly hooked of all
Janthina
species.
Janthina pallida
also has a narrower distribution than most other
Janthina
species, and is one of the least common species throughout most of its range, particularly in the Southwest Pacific, although it is common in the Mediterranean and in southern
Western Australia
.
Palazzi (1979)
recorded
280 specimens
collected on the beaches of Terrasini, Sicily.
Priolo (1959: 186–187)
also listed 21 references in the literature on Mediterranean molluscs mentioning
J. pallida
, including under other species names. Dimitris Poursanidis sent the writer photographs of living specimens collected at
Arina Beach, Heraklion, Crete
, revealing that the eggs are bright pink (
Figs 4A
,
5B
), much deeper in colour than the other consistently pale pink
Janthina
eggs observed. These photographs also reveal that this is the one species of
Janthina
that does not seem to rest its head or snout in the (correspondingly very shallow) sinus in the outer lip. The specimens photographed by Dimitris Poursanidis did not expand out of their shells sufficiently to confirm their external anatomical characters fully, but do not appear to be distinguishable from other
Janthina
species anatomically.
Time range
. No fossil record; living only.