216
worm-like - one of the very few cases in Caenogastropoda (Ponder et al. 2008).
Eulimids are very diverse but their alpha taxonomy is notoriously difficult because
of their small size and the limited disparity of shell morphology among many species of this group. The smooth glossy shell can be interpreted as an adaption to the
parasitic life style.
The number of living eulimid species is unknown but certainly >1000. The fossil
record shows that the family Eulimidae has a minimum age of Campanian (Dockery
1993)—older reports are doubtful. Eulimids have become increasingly diverse and
abundant throughout the Cenozoic (Warén 1983). Some eulimids display a pronounced convergence with Late Palaeozoic subulitoid shells representing the genera
Meekospira and Ceraunocochlis (Fig. 6.2) but the Carboniferous species have a
blunt apex/protoconch instead of a pointed larval shell as found in Eulimidae.
6.2.2.2 Epitoniidae
Epitoniidae (wenteltraps) is a highly diverse caenogastropod family that is associated with or feeds on cnidarians. They feed and live in association with anthozoans,
such as species of Actiniaria, Zoantharia or Scleractinia (e.g., Gittenberger and
Hoeksema 2013 and references therein). Most are considered to be ectoparasitic,
others as carnivorous grazers respectively foraging predators or as symbionts (e.g.,
Robertson 1980; Gittenberger and Hoeksema 2013). Robertson (1980) observed
that an Epitonium species lives in symbiosis with the Coelenterates feeding, together
with another gastropod species representing Coralliophila, on mucous, nematocysts
and zooxanthellae of its host bot not on its tissue of polyps. Bandel (1991) reported
that larger epitoniids feed with their proboscis on anthozoans until their prey dies.
Gittenberger and Gittenberger (2005) observed that epitoniids are attached to the
underside of mushroom corals by mucous threads. They also found that epitoniid
species have specialized on one or few host species.
More than 700 recent epitoniid species have been described validly (Brown and
Neville 2015). The diversity may be much greater because unexplored cryptic radiations are likely (cf. Gittenberger and Gittenberger 2005). Epitoniids have small to
medium sized shells commonly with lamellar axial ribs and a holostomatous aperture (Fig. 6.3a). Epitoniids are unusual for caenogastropods in having a calcitic
shell. They possess the ptenoglossate radula with needle-shaped teeth. Epitoniidae
have a smooth larval shell (Fig. 6.3a). By contrast, Nystiellidae, the likewise parasitic sister-group of Epitoniidae, have a larval shell with axial ribs.
Previous reports of a Middle Jurassic first occurrence of Epitoniidae (Cossmann
1912; Tracey et al. 1993) are doubtful because this species, Proacirsa inornata, has
smooth whorls and its protoconch is unknown. Gründel (2012) placed Proacirsa in
the heterobranch family Gordenellidae and hence outside Epitoniidae. The oldest
known members of Epitoniida with smooth larval shell have a Campanian age
(Dockery 1993). Guzhov (2006) reported a nystiellid from the Upper Jurassic of
Russia. It has an axially ribbed protoconch and teleoconch and thus resembles the
A. Nützel
worm-like - one of the very few cases in Caenogastropoda (Ponder et al. 2008).
Eulimids are very diverse but their alpha taxonomy is notoriously difficult because
of their small size and the limited disparity of shell morphology among many species of this group. The smooth glossy shell can be interpreted as an adaption to the
parasitic life style.
The number of living eulimid species is unknown but certainly >1000. The fossil
record shows that the family Eulimidae has a minimum age of Campanian (Dockery
1993)—older reports are doubtful. Eulimids have become increasingly diverse and
abundant throughout the Cenozoic (Warén 1983). Some eulimids display a pronounced convergence with Late Palaeozoic subulitoid shells representing the genera
Meekospira and Ceraunocochlis (Fig. 6.2) but the Carboniferous species have a
blunt apex/protoconch instead of a pointed larval shell as found in Eulimidae.
6.2.2.2 Epitoniidae
Epitoniidae (wenteltraps) is a highly diverse caenogastropod family that is associated with or feeds on cnidarians. They feed and live in association with anthozoans,
such as species of Actiniaria, Zoantharia or Scleractinia (e.g., Gittenberger and
Hoeksema 2013 and references therein). Most are considered to be ectoparasitic,
others as carnivorous grazers respectively foraging predators or as symbionts (e.g.,
Robertson 1980; Gittenberger and Hoeksema 2013). Robertson (1980) observed
that an Epitonium species lives in symbiosis with the Coelenterates feeding, together
with another gastropod species representing Coralliophila, on mucous, nematocysts
and zooxanthellae of its host bot not on its tissue of polyps. Bandel (1991) reported
that larger epitoniids feed with their proboscis on anthozoans until their prey dies.
Gittenberger and Gittenberger (2005) observed that epitoniids are attached to the
underside of mushroom corals by mucous threads. They also found that epitoniid
species have specialized on one or few host species.
More than 700 recent epitoniid species have been described validly (Brown and
Neville 2015). The diversity may be much greater because unexplored cryptic radiations are likely (cf. Gittenberger and Gittenberger 2005). Epitoniids have small to
medium sized shells commonly with lamellar axial ribs and a holostomatous aperture (Fig. 6.3a). Epitoniids are unusual for caenogastropods in having a calcitic
shell. They possess the ptenoglossate radula with needle-shaped teeth. Epitoniidae
have a smooth larval shell (Fig. 6.3a). By contrast, Nystiellidae, the likewise parasitic sister-group of Epitoniidae, have a larval shell with axial ribs.
Previous reports of a Middle Jurassic first occurrence of Epitoniidae (Cossmann
1912; Tracey et al. 1993) are doubtful because this species, Proacirsa inornata, has
smooth whorls and its protoconch is unknown. Gründel (2012) placed Proacirsa in
the heterobranch family Gordenellidae and hence outside Epitoniidae. The oldest
known members of Epitoniida with smooth larval shell have a Campanian age
(Dockery 1993). Guzhov (2006) reported a nystiellid from the Upper Jurassic of
Russia. It has an axially ribbed protoconch and teleoconch and thus resembles the
A. Nützel