Jökull - 01.12.1986, Blaðsíða 50

calculated on the basis of the minimum number of
individuals needed to account for all of the exoskeletal
parts recovered.
A total of 46 samples were examined for insect
remains and 28 taxa of Coleoptera (beetle) were
identified; 23 of the samples were from deposits previ-
ous to the deposition of the Landnám ash (-900).
Fragments of Dipterous puparia, head capsules of
Hymenoptera (Parasitica), a few larval fragments of
Tricoptera and large numbers of mites, principally
Oribatei, also occurred but only in the case of the
Tricoptera (cf. Buckland et al., 1986) is knowledge of
the fauna sufficiently advanced to allow identification.
Only 11 samples, of which four were pre-Landnám,
were processed for plant macrofossils.
NOTES UPON PARTICULAR TAXA
Hydraena britteni Joy
By far the most surprising find in the Ketilsstadir
samples were large numbers of heads, thoraces and
elytra of a small Hydraenid (sensu Lohse, 1971) beetle
whose identification as Hydraena britteni Joy was
confirmed by the recovery of an abdomen, complete
with aedeagus, from sample BRl/8. This insect has
yet to be found living at the present day in Iceland
and some of the implications of its discovery have
been discussed elsewhere (Buckland et al., 1983). An
inhabitant of wet Sphagnum moss (Lohse, 1971) and
shallow flooded grassland (Balfour-Browne, 1958), it
is difficult to collect by standard entomological
techniques and it may have been overlooked in Ice-
land. It has also been found fossil in ninth to fifteenth
century deposits at Holt in Eyjafjallasveit, some 32km
to the west (Sveinbjarnardóttir, 1983). Its presence in
samples of sixteenth to seventeenth century age from
archaeological deposits on the farm site at Stóraborg,
east of Holt (Perry et al.\ 1985), may, however, be re-
lated to peat taken to the site as fuel, a problem noted
elsewhere in samples from wholly man-made deposits
(Hall et al., 1981). In Iceland, there is some evidence
to suggest that the post-medieval period includes some
of the coldest years since the last glaciation (cf. Thór-
arinsson, 1981; Buckland et al., 1986) and the possi-
bility of a ‘Little Ice Age’ extinction, as recently sug-
gested by Girling (1984) for the water beetle Gyrinus
colymbus Er. in England, has been considered (Buck-
land et al., 1983).
Lathrobium brunnipes Fabricius
Whilst the identification lacks the confirmatory evi-
dence of the aedeagus, there can be little doubt that
the many fragments of a species of Lathrobium in the
Ketilsstadir samples belong to L. brunnipes F. and not
the more widespread species at the present day, L.
fulvipenne. The former is known in Iceland from a few
specimens taken by Lindroth (1965) at two localities
in Hornafjördur and a recent find in Landbrot,
W.-Skaftafellssýsla (Erling Ólafsson, pers. comm.).
Like H. britteni, it is also an insect of Sphagnum bogs
and is widely distributed in upland areas of northern
Europe (Lohse, 1964). This Staphylinid beetle is a
much more common fossil than its present frequency
would lead one to expect, occurring also at Holt in
Eyjafjallasveit and Kópavogur, near Reykjavík (Buck-
land et al., 1986) in some numbers in both pre- and
post-Landnám deposits. Whether the widespread
drainage and improvement of suitable habitats has
resulted in its present rarity is uncertain.
Bryaxis puncticollis Denny
Six individuals of the minute Pselaphid beetle
Bryaxis puncticollis were found in Ketilsstadir de-
posits and the species is clearly part of the fauna
which predates the arrival of man in Iceland. It is
known at the present day from only two localities,
Dynjandi in Hornafjördur (Lindroth, 1931) and
Ásólfsskáli in Eyjafjallasveit (Lindroth et al., 1973).
The modern Icelandic records are from grassland but,
in Central Europe, the species is a pronounced forest
animal, occurring “in withered leaves at the base of
old tree stumps” (Larsson & Gígja, 1959). It is possi-
ble, therefore, that it should be regarded as an Ur-
waldrelikt in the Icelandic fauna (cf. Buckland (1979)
on the British forest fauna), although Pierce (1957)
notes the beetle from habitats similar to its Icelandic
one in Britain.
THE PALAEOENVIRONMENT
Pre-Landnám
Whilst there is evidence from elsewhere in southern
Iceland for settlement before the eruption which dis-
tributed the so-called ‘Landnám tephra’ over much
of the country (Larsen, 1984), this distinctive layer
provides a suitable horizon before which the land-
scape is essentially unaffected by man. For sev-
eral hundred years, until Landnám, the bog at Ket-
ilsstadir shows relatively little environmental change.
Neither stratigraphy nor macrofossils provide evi-
dence for birch woodland occupying the surface of the
bog, although fragments of wood occur in several pre-
Landnám samples, suggesting that trees occasionally
gained a foothold on temporarily drier areas. Whilst
48