(^62) SAMUEL T. TURVEY
Fig. 4. Area cladogram derived from the strict consensus cladogram in Figure 3a. The nodes numbered 1 to 4
are discussed in the text.
2001). These three regions are here interpreted
as representing a single Early Ordovician SE
Asian palaeogeographic area. A restricted
interpretation of Cimmeria is thus employed in
this analysis.
Area assignment was generally straight-
forward, with the exception of some Asian and
Australian taxa. The Himalayan species Caly-
mene nivalis Salter, 1865b was interpreted as
representing Neseuretus by Dean (1967b, 1975),
Fortey & Morris (1982), Morris & Fortey (1985)
and Rabano (1990); examination of the type
material in the Natural History Museum,
London, suggests that this species should instead
be referred to Sarrabesia. 'Synchomalonotus'
sulcatus Kolobova in Sokolov & Yolkin, 1978,
from the Ashgill of Uzbekistan, previously
reassigned to Sarrabesia by Hammann & Leone
(1997), is here interpreted as a species of
Vietnamia. Calvmenesun longinasuta Dean &
Zhou, 1988, from the early Ashgill of the Zap
Valley, SE Turkey, is extremely similar to
Neseuretinus turcicus, and is certainly con-
generic. Several different authors (Banks 1988;
Corbett & Banks 1974; Legg 1976) have
recorded the presence of reedocalymenine taxa
in Australia, but the taxonomic position of these
specimens has remained unclear. Edgecombe et
al. (1999) tentatively assigned some of this
material to Sarrabesia; although other Aus-
tralian material may well represent different
reedocalymenine taxa, only Sarrabesia is
considered to occur in Australia during the
Ordovician in this analysis.
The consensus cladogram indicates that
Neseuretus as currently understood represents
both a paraphyletic and a polyphyletic genus.
Whereas Neseuretus sensu stricto (i.e. Neseuretus
exclusive of N. sanlucasensis, N. intermedius and
N. planus) is known to have occurred in
shallow inner-shelf conditions amenable to high-
resolution biogeographic analysis, and Caly-
menella and Pradoella occupied similar
shallow-water conditions during the Early
Ordovician (e.g. Beckly 1989; Rabano 1990), the
ecological requirements of Middle Ordovician
Asian reedocalymenine taxa, and the species
previously assigned to Neseuretus which occur at
the base of the Neseuretinus-Sarrabesia-
Vietnamia subclade, are less well understood
or are known to have differed. Neseuretinus
turcicus is recorded from offshore shallow shelf
