>Can someone tell me whether there are Turritella with beaded spirals? At
>least on the early whorls?

Certainly are. Many species have granular or even strongly beaded
spiral cords on the upper spire whorls.  If anyone finds a spiny one,
please send it to me. Many retain beading to large size eg some of
the New Zealand fossil Zeacolpus spp. Said beading can be weak or
distinct and tends to be rather irregular on later whorls, produced
by growthlines crossing spiral cords.

>Or is Turritella necessarily only with spiral sculpture?

>I've got a small specimen with beaded spirals and a flattened base. Not sure
>what else it could be.

No way to tell without seeing an image. Can you send me one please?
No guarantee that I'll be able to place it even to generic level, as
it'll be immature if it's triphoroid, but at least I'll be able to
tell you what family or even genus it belongs to if the protoconch
shows up well.

>How about Triphoridae?  These are similar in shape to Turritellidae,
>typically have beaded sculpture, and are all rather small. Most of them are
>sinistral, but I don't think all of them are.

There are lots of dextral triphorids (Adelacerithiinae, Metaxiinae).
They, like the Cerithiopsidae (both of these families belong in
superfamily Triphoroidea or Cerithiopsoidea, depending on where you
look, and are distantly related to Epitoniidae), show determinate
growth ie the shape of the bodywhorl changes at full maturity and the
shell ceases growing. The flat base becomes convex; the aperture may
be slightly constricted and may bear several tubes reminiscent of
typhine muricids, though most have only the siphonal canal. They lack
a strong labral sinus... turritellids are characterized inevitably by
a deep sinus in the outer lip (labrum).

Triphoroidea most often bear spiral cords with strong gemmae, fas
stronger than any turritellid, but some are not gemmate. They tend to
have odd sculptured protoconchs, which may be narrowly conical and
bear a couple of fine spiral lirae with fine complex other sculptural
elements or else low domelike ones with strong axial folds.
Turritellid protoconchs are smooth and generally conical.

Almost inevitably the early whorls of turritellids are concave
medially, with a slight angulation at a cord above the suture.

But that turritellid sinus is the easiest giveaway... just look at
the growthlines.

Some workers place Turritellidae in its own superfamily
Turritelloidea, which makes sense to me. They are very different to
cerithioids. As to turritellid genera, in NZ and Australia what would
be regarded as subgenera elsewhere are elevated messily to generic
rank, based largely on the inception of the spiral elements during
early growth. This does not make sense to me, and until good
anatomical and molecular work is done, I personally will prefer to
regard these as subgenera (Maoricolpus, Gazameda, Zeacolpus,
Tropicolpus, Amplicolpus, Stiracolpus...).

A major characteristic of turritellids is lack of interest by collectors!

Speaking of Cerithiopsidae and Triphoridae, I would love to see some
good work spelling out exactly WHY they are still paced in separate
families. I remain unconvinced, but have yet to read a diagnosis
separating them.
--
Andrew Grebneff
Dunedin, New Zealand
64 (3) 473-8863
<[log in to unmask]>
Fossil preparator
Seashell, Macintosh & VW/Toyota van nut
I want your sinistral gastropods!
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