Beu: Evolution of Janthina and Recluzia 
161 
evolved by at least Piacenzian-early Gelasian time, it likely 
also evolved from J. krejcii, the Zanclean species without 
spiral folds. Janthina pallida is assumed to be a daughter 
species that originated from J. globosa. The evolution of J. 
globosa would have required a moderate increase in spire 
height, increase in whorl convexity, loss of all axial ridgelets, 
and development of a wider, deeper sinus with its apex in 
the centre of the outer lip, although the sinus is significantly 
shallower than that of J. exigua. If the suggested phylogeny 
is correct, it implies that the progression of the outer lip sinus 
from a narrow feature at the base of the lip to occupying the 
entire height of the outer lip, with its centre in the middle 
of the lip, evolved twice; it took place in descendants of 
both J. chavani and J. krejcii. This lends some doubt to the 
suggested phylogeny, and its significance will not be clear 
until the function(s) of the sinus are clear. 
The four living Janthina species that lay eggs enclosed in 
capsules clearly fall into two pairs of closely similar species. 
Janthina globosa and J. pallida resemble each other much 
more closely than either does the other pair of similar species, 
J. exigua and J. umbilicata. It is feasible that each pair of 
species resulted from the origination of a daughter species 
from the parent species as a result of geographical isolation, 
i.e., “standard” allopatric speciation, within an enclosed area 
such as the Mediterranean Sea. This possibly was aided by 
their occurrence in isolated neuston “rafts” (e.g., Bennett, 
1840: 63; Dakin, 1933; Savilov, 1969). Subtle genetic 
differences likely result between “rafts”, and could have led 
to genetic drift and speciation during isolation as a result of 
Plio-Pleistocene glacial-interglacial sea-level fluctuations. 
Sympatric speciation as a result of ecological change across 
an ecotone, such as a sharp temperature gradient, is another 
possible explanation (e.g., Johannesson et al ., 2010; Krug, 
2011; Bowen et al., 2013). These species are all so similar 
in most characters that their inclusion in the single genus 
Janthina seems reasonable. The suggested phylogeny of 
Janthina is shown in Figure 23. 
The loss of spiral folds is a significant event in the 
evolution of Janthina. Spiral folds are the character by 
which Bronn (1861) separated Hartungia from Janthina. 
It could be interpreted as indicating that J. krejcii was the 
earliest species of a separate genus Iodina Morch, 1860, 
which evolved from Janthina during Zanclean time. Iodina 
would include the species now identified as Janthina krejcii, 
J. exigua, J. globosa, J. pallida and J. umbilicata. Janthina 
would then include only J. typica, J. chavani and J. janthina. 
However these species are classified, there is no doubt 
that Hartungia is a synonym of Janthina if the proposed 
phylogeny approaches reality. At present the phylogeny of 
Janthina species is so little understood and all species are so 
similar that it is preferable to retain all species in Janthina. 
While the suggested phylogeny is plausible, it is of course 
based solely on morphology and should be tested, including 
evaluating the recognition of Iodina, by comparing molecular 
sequences. It would be preferable if all living Janthina and 
Recluzia species were compared with as many benthic 
species of Epitoniidae as possible, including species of Alora, 
Surrepifungium and Alexania. 
Systematic revision 
Gastropoda 
Epitonioidea Berry, 1910 (1812) 
Epitoniidae Berry, 1910 (1812) 
Scalariidae Lamarck, 1812. 
Janthinidae Lamarck, 1822. 
Recluziidae Iredale & McMichael, 1962, not available; 
Bouchet & Rocroi, 2005: 72, 254. 
Epitoniinae Berry, 1910 (1812) 
Janthina Roding, 1798 
Janthina Roding, 1798: 75. Type species (by tautonymy): 
Helix janthina Linnaeus, 1758 (H. janthina cited in 
synonymy of Janthina violacea Roding, 1798); Recent, 
cosmopolitan. 
lanthina Lamarck, 1801: 427. Incorrect subsequent spelling 
of Janthina Roding, 1798 (many later authors used this 
incorrect spelling). 
Janthinus Montfort, 1810:214. Incorrect subsequent spelling 
of Janthina Roding, 1798. 
Zanthina Fischer von Waldheim, 1823: 236. Incorrect 
subsequent spelling of Janthina Roding, 1798. 
Ametistina Schinz, 1825a: 586 (suppressed under ICZN 
Opinion 989, 1972). 
HyanthinaVoxxo , 1841: 87. Incorrect subsequent spelling of 
Janthina Roding, 1798. 
Achates Gistel, 1848: 169 (unnecessary substitute name for 
Janthina)', Morch, 1860:277. Type species (automatically 
that of the substituted name): Janthina violacea Roding, 
1798 (= Helix janthina Linnaeus, 1758). 
Ametistina H. Adams & A. Adams, 1854: 86 (nomen nudum). 
Amethystina Chenu, 1859: 118 (nomen nudum). 
lodes Morch, 1860: 273. Type species (by subsequent 
designation, Tryon, 1887: 34): lodes britannica “Leach” 
Forbes & Hanley, 1852 {= Helix janthina Linnaeus, 1758). 
Iodina Morch, 1860: 282. Type species (by subsequent 
designation, Tryon, 1887: 34): Janthina exigua Lamarck, 
1816; Recent, cosmopolitan. 
Amethistina Morch, 1860: 282; section of nominotypical 
subgenus of Janthina', attributed by Morch to “Schintz”. 
Type species (by subsequent designation, Tryon 1887:34): 
Janthina pallida Thomson, 1840; Recent, cosmopolitan. 
Hartungia Bronn, 1861: 110. Type species (by monotypy; 
combined description of a new genus and species): 
Hartungia typica Bronn, 1861; early Pliocene (Zanclean), 
Santa Maria Island, Azores; late Messinian to early 
Piacenzian, cosmopolitan. 
Jantina Weinkauff, 1873: 66. Incorrect subsequent spelling 
of Janthina Roding, 1798. 
Jodes Marschall, 1873: 122. Incorrect subsequent spelling 
of lodes Morch [ex Leach ms], 1860. 
Jodina Marschall, 1873: 122. Incorrect subsequent spelling 
of Iodina Morch, 1860. 
Eligmope Dennant, 1889: 48 ( nomen nudum). 
Heligmope Tate, 1893: 328. Type species (by monotypy): 
Heligmope dennanti Tate, 1893 (= Hartungia typica 
Bronn, 1861). 
Amethystina Pallary, 1920: 56. Incorrect subsequent spelling 
of Amethistina Morch, 1860. 
