Aporrhaidae, their evolution from Rupelian, Oligocene onwards

Abstract

The family Aporrhaidae (Gastropoda: Stromboidea) comprises six extant species. In a study of the soft parts
of three of them, a deep evolutionary split between “Aporrhais” serresiana on the one hand and Aporrhais
pespelecani/Arrhoges occidentalis on the other hand was found.
This talk presents an attempt to explain this based on an analysis of the fossil record. Several thousand
specimens from Rupelian (Oligocene) to recent faunas were examined and classified regarding their age
and geographical origin. A search for morphological patterns reveals some basic characters: the form of
rostrum and spines and the existence of a ventral callus. These characters make it possible to initially split
the aporrhaids into three basic lineages. However, detailed examination of the callus in relation to environmental
factors and the sympatric occurrence of two differently callused species point to the existence
of a fourth lineage. The species and characters of the lineages are a) the spiky aporrhaids with fingers like
in “Aporrhais” uttingeriana or “Triacontium” mirandum; b) those without a callus, but with a shovel-like
rostrum and with a solid wing like in “Aporrhais” speciosa or Aporrhais pespelecani; c) those with a thick,
sledge-like ventral callus, like in “Aporrhais” margerini or “Strombopugnellus” digitolabrum and d) those with
a thin, irregular ventral callus like in “Cerycium” paradoxum or “Aporrhais” unisinuata.
The formation of isolated or nearly isolated basins like the Central and Eastern Paratethys, the Mediterranean
and the North Sea basin further splits the above mentioned four aporrhaid lineages. It leads to a complex
evolutionary lineage pattern, which is at the moment not reflected in taxonomy and nomenclature. Most of
the examined specimens fit into this pattern; some, like “Aporrhais” serresiana, do not. Possible explanations
for the existence of these extra-pattern species are hybridization or introgression, extreme environmental
conditions, immigration from other areas, and merging evolutionary lineages.

Full text

Aporrhaidae

Ulrich Wieneke


Introducon

Recent Aporrhaidae
Aporrhais eleganssima  !"#
Aporrhais pesgallinae $ !%&
Aporrhais senegalensis ' (&()
Aporrhais serresiana ' (*()
Aporrhais pespelecani '+ ",()
Arrhoges occidentalis (Beck, 1836)


-
.

/
Study of the stromboidean Anatomy
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/
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Method

Results

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%5
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The Callused Ones

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
&(5
The Spiky Ones

The Normal Ones
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
&35

Discussion

7
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9 #+>9:?/$*,#3% 4 #'@)
Paleogeography

The Evoluonary Cac

Summary
A-@
1/

Thank you
for your a&enon
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