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WORKING CLASSIFICATION OF THE GASTROPODA 271
1 Scenelloidea, Yochelcionelloidea, Khairkhaniidae, and
Pelagiellidae included by Parkhaev (2002) in his sub-
class Archaeobranchia of the Gastropoda Conversely,
the families Maikhanellidae Missarzhevsky, 1989, and
Purellidae Vassiljeva, 1990, are excluded from Gas-
tropoda by Parkhaev. Contents and classification after
Parkhaev (2002), with nomenclatural adjustments.
2 Protoconchoididae treated as Gastropoda by Horny (1 997).
3 Archinacellidae treated as Gastropoda by Horny ( 1 997)
and Peel & Horny (1999), included in Patellogastropoda
by Geyer ( 1 994), placed in Monoplacophora by Wahlman
(1992) The archinacellid Barrandicella looks very simi-
lar to modern thin-shelled Monoplacophora. The lack of
visible lateral muscle scars is shared with most modern
Monoplacophora.
* Linsley & Kier (1984) established a separate class
Paragastropoda for mainly sinistral Early Paleozoic "gastropods",
consisting of the orders Orthostrophina and
Hyperstrophina [= Onychochiloidea + Macluritoidea +
Euomphaloidea]. Ponder & Lindberg (1997) suggested
that the Paragastropoda may include, at least in part,
early eogastropods. Geyer (1994) expanded the con-
tents of Pelagielloidea (which he treated as an order
Pelagiellida) and classified them in a class Amphi-
gastropoda together with the orders Bellerophontida,
Cyrtolitida, and Tryblidiida.
^ Assignment of Paleozoic symmetrical univalved mollusks
("bellerophonts") either to Gastropoda or to
Monoplacophora or Tergomya is controversial. The
Bellerophontida were not considered gastropods by
Geyer (1994). Bande! (1997) and Fryda (1999a) revived
the concept of a separate class Amphigastropoda for
the Bellerophontida. P J Wagner (2002) considered the
bellerophonts to be polyphyletic, with "tropidodiscids" as
ancestors of the "Archaeogastropods" and sinuitine
bellerophonts as secondarily derived bellerophonts
which would be the sister taxon of the murchisoniines.
^ Content and classification of Bellerophontoidea follows
Wahlman (1992), modified by Horny (1996) Sinuitidae,
treated as Monoplacophora by Wahlman (1992), here
placed in Bellerophontoidea after Horny (1992a). The
family Coreospiridae Knight, 1947 may also belong in
Bellerophontoidea.
^ Euomphaloidea included in Linsley & Kier's class
Paragastropoda (see Note 4 above). P. J. Wagner (1995)
suggested that a clade "euomphalids" unites Euomphalidae
(part) + Euomphalopteridae + Helicotomatidae
(part) + Pseudophoridae + Planitrochidae. Bändel & Fryda
(1998) ranked Euomphaloidea as a separate class
Euomphalomorpha, which is discussed by NiJtzel (2002a)
^ The order Macluritina, established by Cox & Knight
(1960), unites the Cambrian-Ordovician hyperstrophic
gastropods with sinistrally coiled teleoconch and calcareous
operculum. Macluritoidea included in Linsley &
Kier's class Paragastropoda (see Note 4 above).
^ The name Cycloridae has priority, but because the type
species of Cyclora appears to be a juvenile, badly preserved
specimen, we do not want to displace the wellknown
name Holopeidae.
'° Placed in Platyceratoidea by Tracey et al. (1993).
^^ This concept unites the Cambrian-Devonian sinistrally
coiled gastropods having sinistrally coiled, multiwhorled
protoconchs (Dzik, 1983; Fryda & Rohr, 1999). Alterna-
tive classifications were suggested by Knight et al.
(1960), Golikov & Starobogatov (1975) and Linsley &
Kier (1984)
^2 Fryda & Bändel (1997) established the order Stylo-
gastropoda to contain high-spired "loxonematoid" taxa
with archaeogastropod-type protoconch. They excluded
"
high-spired "loxonematoid taxa with multispiral larval
shells from Stylogastropoda and placed them in
Caenogastropoda. The Stylogastropoda probably involves
the majority of Ordovician to Devonian genera
assigned by Knight et al. (1960) to Loxonematoidea.
^3 Contents after P. J. Wagner (2002), who used Lopho-
spiroidea as the name of the superfamily and noted that
"due to the highly polyphyletic nature of the
Trochonematoidea and also to the very dissimilar taxon
definitions, it is recommended that the Trochonematoidea
be abandoned".
^'' Classification based on Lindberg (in Beesley et al., 1998).
A position of the Patellogastropoda as sister group to the
rest of the modern gastropods has long been emphasized
(eg. Ponder & Lindberg, 1997), but in recent mo-
lecular work (Colgan et al., 2003) they appeared as a
derived clade of some Vetigastropoda This fits with the
fact that the juvenile patellogastropod radula is of
rhipidoglossate type (Smith, 1935; Waren, unpublished).
The concept of Eogastropoda includes the hypothetical
coiled ancestors of the Patellogastropoda; thus some Paleozoic
taxa classified below under Orthogastropoda may
(or probably) belong in Eogastropoda.
^^ Reversal of precedence; see Nomenclátor.
^^ The distinctiveness of the radula, which seems to have
been the main reason for a superfamily level for this
group (McLean, 1990b), seems to be an apomorphy.
Fretter (1990) considered neolepetopsids closer to
Acmaeidae than to other patellogastropod limpets from
anatomical data and Harasewych & McArthur (2000)
indicated close relations to Acmaeidae from 18S infor-
mation, but were confused by the presence of a central
tooth in the radula. The central tooth, however, is present
in young Patellidae, Nacellidae and Acmaeidae, but is
lost during ontogeny (Waren, unpublished).
^' Position of Damilinidae after Peel & Horny (1999),
'^ Harasewych & McArthur (2000) considered the inclu-
sion of the Palaeozoic Lepetopsidae in Neolepetopso-
idea conjectural Knight (1 941 ) noticed that, in the three
specimens of Lepetopsis levettei White, 1882 he had
examined, "the apex is occupied by a hole with somewhat
irregular though seemingly rounded margins"; he
added "It is not thought that this represents an opening
similar to that of Fissurella, but it is possible that it does".
^3 Content of Vetigastropoda follows Ponder & Lindberg
( 1 997), with the addition of Porcellioidea (Bändel, 1 993a,
as Cirroidea) and Amberleyoidea, not explicitly included
in Vetigastropoda by Ponder & Lindberg. Arrangement