Aquatic Entomofauna: Bug and Beetle Diversity of Hyderabad - Aquatic Ecosystem: Biodiversity, Ecology and Conservation - page 107

from the adults, and their diversity is high. In
temperate regions, beetles from most major
groups commonly exhibit univoltine life cycles.
A particularly interesting suite of aquatic and
semiaquatic habitats inhabited by beetles occurs
at the edge of the sea. In general, insects have not
made major inroads into salt water, but a consid-
erable number of beetles are able to tolerate such
environmental conditions by either physiological
tolerance or behavioural adaptation. The
Coleoptera are divided into four suborders. The
fi rst two are very small relict groups, of which the
Myxophaga are more or less aquatic, mainly in
running water. The Adephaga or carnivorous bee-
tles are a large suborder containing six aquatic
families. In the very primitive Amphizoidae,
nearly all the Dytiscidae and the Noteridae, the
larvae are metapneustic, breathing by means of a
single pair of abdominal spiracles. In the primi-
tive Hydrobiidae, the Haliplidae, one genus of
Dytiscidae and the Gyrinidae, the larvae have tra-
cheal gills. Beetles are found in a very wide range
of aquatic habitats. Aquatic beetles are classifi ed
as clingers, climbers, sprawlers, swimmers, div-
ers and burrowers.
Water beetles display a wide array of respira-
tory adaptations. Many larvae are able to breathe
via the integument; and many of them are
equipped with various kinds of gills (tracheal
gills, spiracular gills), which may be even retract-
able, as in many Dryopidae. In contrast to the lar-
vae, adults have no gills. Most species carry a
smaller or larger air bubble with them, which is
in contact with the tracheal system. This air sup-
ply may be stored in the subelytral space (e.g.
Dytiscidae, Gyrinidae), underneath the coxal
plates (Haliplidae), on the ventral surface
(Hydrophilidae) or on any part of the body, where
it is usually held by hydrofuge pubescence or
scales; in Elmidae, for instance, the air bubble
can replace oxygen through diffusion of dis-
solved oxygen from the surrounding water while
the beetle is fully submerged. In such a case the
air bubble is called gas gill (or plastron) because
it functions as a physical gill. Two kinds of
plastron can be distinguished microplastron and
macroplastron. The Gyrinidae, or whirligig bee-
tles, occur on the surface of ponds in aggrega-

tions of up to thousands of individuals. Water
beetles can be used to control water plants that
have become pests.
The major studies on aquatic Coleoptera also
include the works from Andhra Pradesh
(Mukhopadhyay and Ghosh 2003 ), West Bengal
(Biswas and Mukhopadhyay 1995 ) and Sikkim
(Mukhopadhyay and Ghosh 2003 ). More than
223 species of aquatic coleopterans are known
from India. Only 31 species of beetles are
reported from the present study. More intensive
survey spread over different seasons would be
required to provide a complete picture of the
aquatic beetle diversity of this area.

Key to Five Families of Adult Coleoptera,
from Hyderabad
01. Each eye divided into two, usually shiny
black elytra, often seen swimming on the
water surface in groups - Gyrinidae
Eyes normal, not divided into two - 2
02. Plates covering almost the entire fi rst leg
segment and fi rst few abdominal segments.
Hind coxa, hind femur and basal abdominal
ventrites concealed under conspicuous
“hindcoxal plates” - Haliplidae
No plates on ventral surface covering legs
or abdominal segments - 3
03. First segment of hind legs dividing the fi rst
abdominal segment. Overall body shape
streamlined. Metasternum with characteristic
lateral “wings”. Metacoxae large, posteriorly
with a paired posterior metacoxal process. Size:
1-50 mm, often streamlined - Dytiscidae
First abdominal segment not divided by
hind coxae - 04
04. Maxillary palps long, visible dorsally.
Antennae with last four segments in the form
of a club starting with a “cuplike” segment,
pubescent antennal club with 3 segments,
abdomen usually with 4-5 clearly visible
sternites - Hydrophilidae
Maxillary palps short, not extending beyond the
head so no seen in dorsal view. Antennae may
be clubbed or not but not as above. Antenna
long or short, 7-11 segments, second segment
never greatly enlarged. Frontoclypeal suture
usually present. Size: 0.8-11 mm. Usually