Beu: Evolution of Janthina and Reduzia 
127 
Table 1 . Similarities and differences between benthic Epitoniidae, Janthina species and Reduzia species; based on Collin 
(2000: table 1), Churchill et al. (2011a: supplementary table SI) and AGB personal observation. Characters of unknown 
condition queried (?); the likely condition in Reduzia is stated where known. 
character 
benthonic 
Epitoniidae 
Janthina 
species 
Reduzia 
species 
neustonic, with bubble float 
no 
yes 
yes 
feeding on (mainly) 
benthic cnidarians 
Velella, Porpita, etc. 
minyadid anemones 
shell calcitic 
yes/no? 
yes 
yes 
obvious periostracum 
no/intritacalx 
no 
conchiolin 
teleoconch axial ridges prominent 
yes/no 
yes/no 
no 
shell colour 
white/brown 
violet 
yellow-brown 
sinus in outer lip 
no 
yes 
no 
operculum in adult 
yes 
no 
no 
eyes in adult 
obvious 
minute 
? (not obvious) 
aphalic males 
yes/no 
yes 
yes 
cephalic tentacles 
single 
forked 
single 
epipodia 
no 
yes 
no 
unpaired labial gland 
large 
reduced 
large 
spermatozeugmata 
yes 
yes 
?yes 
protandrous hermaphroditism 
yes 
yes 
yes 
ptenoglossate radula 
yes 
yes 
yes 
divided radula and odontophore 
yes 
yes 
yes 
stylets in inner salivary glands 
yes 
no 
yes 
central tooth distinctive 
yes/no 
no 
no 
purple dye secreted 
yes/no 
yes 
no 
larval pigmented mantle organ 
yes 
yes 
?yes 
acrembolic proboscis 
yes 
no 
no 
cuticularized oesophagus 
yes 
yes 
?yes 
osphradial ridges 
1 or 3 
1 or 2 
7 
open pallial oviduct 
yes 
no 
no 
pairs of salivary glands 
2 
2 
2 
statocysts 
yes 
no 
yes 
egg capsules 
small, linked 
large, separate 
large, separate 
chalazae 
yes 
no 
no 
number of adult teleoconch whorls 
5-20 
3-5.5 
4.5-7 
juvenile stage associated with 
yes, on adult 
no, juvenile 
yes, on adult 
adult’s egg mass or float 
egg mass 
has float 
float 
cnidarians (e.g., Robertson, 1963,1970,1981a; Bosch, 1965; 
Gittenberger, 2003; Gittenberger & Gittenberger, 2005). 
Epidendrium reticulatum (Habe, 1962) is an example of a 
benthic epitoniid species, tentatively assigned to Epidendrium 
by Nakayama & Hasegawa (2016: 21), that feeds on the 
plumulariid hydrozoan Dentitheca habereri (Stechow, 1909), 
which in turn lives attached to the anthozoan Parazoanthus 
gracilis (Lwowsky, 1913) (Habe, 1962; Nakayama & 
Hasegawa, 2016). Janthina and Recluzia appear merely to 
be epitoniids that feed on neustonic cnidarians, mainly the 
siphonophore Physalia and the chondrophores Porpita and 
Velella in the case of Janthina (e.g., Hardy, 1956; Ganapati 
& SubbaRao, 1959; Okutani, 1964; Palazzi, 1979; Rolan & 
Trigo, 2003) and “the rare floating anemone Minyas ” in the 
case of Reduzia (Abbott, 1968: 93, text-fig.; Abbott, 1974: 
114; Minyadidae, Cheng, 1975: 195; Robertson, 1997: 11; 
2007a: 7) (note that Actinecta Blainville, 1830 has priority 
over the j unior homonym Minyas Cuvier, 1817; Fautin et al., 
2007; Fautin, 2013). The lack of a fossil record of Reduzia 
species indicates that Reduzia adopted the neustonic habit 
very recently, in geological terms. Although the most 
spectacular siphonophore, Physalia, has no fossil record 
(Harrington & Moore, 1956: 147), fossils convincingly 
similar to Velella are known from Devonian rocks and fossils 
similar to Porpita from Ordovician rocks (Harrington & 
Moore, 1956: 149-150). The origination of its main prey 
was not an impetus for the evolution of Janthina. 
The most important consideration for the classification of 
Janthina and Reduzia is the phylogenetic significance of the 
synapomorphies that previously suggested the recognition 
of a separate family Janthinidae. Similarities and differences 
between benthic Epitoniidae, Janthina and Reduzia are listed 
in Table 1. Janthina and Reduzia species share with benthic 
Epitoniidae the ptenoglossan radula, aphalic males (also the 
case in some but not all benthic epitoniids), protandrous 
hermaphroditism, the radula and large odontophore being 
subdivided into two and used as an eversible grasping organ 
to pull large pieces of food into the gut (Graham, 1965: 
336, fig. 5; see below), a hypobranchial gland secreting 
a purple dye (Robertson, 1983: 10; 2007a: 9) (although a 
purple secretion apparently is not produced by Reduzia 
species), a larval pigmented mantle organ, a cuticularized 
oesophagus, two pairs of salivary glands, stylets in the inner 
pair of salivary glands (in Epitonium and Reduzia, but not 
Janthina, Fretter & Graham, 1962: 260; Churchill et al., 
2011a: supplementary table SI), and longitudinal ridges 
on the osphradium (although not as yet demonstrated in 
Reduzia). Further differences listed by Collin (2000: table 
