(Coleoptera: Chrysomelidae: Alticinae)
Head (Figs. 1-3 and 4-6)
Three important regions of the
flea beetle head, common to Coleoptera in general, are the
epicranium, epistome and basicranium (sensu Du Porte 1960, Matsuda
1965, sensu Kryzhanovsky 1983). The epicranium consists of the
vertex, frons and gena. The frons is usually recognizable as a
distinct ridge, separated from the gena by the frontogenal suture
(Fig. 4). The vertex is situated dorsal to
the frons and sometimes
delimited by a transfrontal suture. Usually there are two raised
areas on the lower part of the vertex known as antennal calli. Du
Porte (1960) named the region of the vertex bearing these calli
the epifrons. For the purpose of our key and descriptions we have
defined the area between the vertex and basicranium as the "facial
part" of the head (Fig. 4) .
The epistome
is situated on the
anterior margin of the head, delineated from it by the
frontoclypeal suture. This suture is indistinct in the majority of
Palearctic flea beetles.
The basicranium (Fig. 6) consists of the combined gula and
submentum, situated on the midventral part of the head capsule
between the gular and hypostomal sutures. There are two posterior
tentorial pits at the juncture of these two sutures.
Mouth parts (Figs. 7-10 and 11-12)
The mouth parts consist of a
labrum, labium, and the paired mandibles and maxillae.
The
alticine labrum is a flat, sclerotised, rectangular structure with
two posterolateral elongated tormae (Fig. 8) and numerous marginal
setae on the anterior margin. The upper surface has a number
(usually 6) of symmetrically placed setiferous pores.
The
mandibles are highly sclerotised, symmetrical structures with
triangular bases. The apex of this triangle is situated ventrally
(Fig. 9). The outer surface is strongly convex and has very
complicated sculpturing. The inner surface is strongly concave
with a membranous prostheca covered by many small setae. The
absence of a mola (with the probable exception of Blepharida,
Ophrida, and Podontia) is one of the more notable features of the
alticine mandible. There are 5 mandibular teeth in the majority of
Palearctic flea beetles.
The maxilla of flea beetles consists
of a basal segment (cardo), basi- and mediastypes, galea, and
lacinia; a 4-segmented maxillary palpus is attached to each
basistipe. The basal segment of the palpus is usually very small
(Fig. 11).
The flea beetle prementum is attached
to the mentum
and bears a pair of 3-segmented palpi, which differ in morphology
from genus to genus (Fig. 12).
Antennae (Figs. 13-16)
Alticine
antennae are usually 11-segmented and filiform. Only 2 genera
differ in segment number: Psylliodes and Nonarthra have 10 and 9
segments, respectively. The antennae of Nonarthra are serrated. In
some genera living on the soil near plant roots (e.g. Mniophila,
Orestia) the antennae have acquired a moniliform structure.
Thorax (Figs. 17-21 and 22-25)
For thoracic structures we have
adapted the terminology proposed by Snodgrass (1935), Crowson,
(1938, 1944) and Hlavac (1972).
The prothorax of the Alticinae
is a highly sclerotized structure nearly lacking sutures. In
several genera, the pronotum has a transverse antebasal impression
and/or two short, laterally placed impressions. The lateral
infolded portions of the pronotum, visible in a ventral view, are
the hypomera. It is important to mention that the flea beetle
prothorax lacks visible pleura. The prosternum is usually narrow,
especially the intercoxal prosternal process. The procoxal
cavities are termed "closed" if the inner hypomeral projection
touches the posterolateral part of the intercoxal prosternal
process.
The meso- and metathoraces have
been neglected as
sources of diagnostic or phylogenetic characters. In figures 19-22
we have simply labeled some of the more prominent morphological
features.
The metendosternite is an internal
structure, attached to the posterior margin of the metasternum
between the metacoxal cavities (Fig. 23). This structure is useful for
extrapolating intergeneric relationships. It also provides
important characters for generic identification (Konstantinov and
Lopatin 1987).
Wings and appendages (Fig. 26)
The elytra (= mesothoracic wings) of
Alticinae exhibit a large
diversity of surface sculpturing. Sometimes they are covered by
irregularly placed punctures, or with punctures arranged in
striae. The interspaces between striae can be minutely punctate
and/or shagreened.
The metathoracic wing venation is a popular
subject for comparative morphological studies at the family level.
The commonly accepted terminology (Suzuki 1994) is given on figure
26.
The legs of flea beetles consist of coxae, trochanters,
femora, tibiae and tarsi (Fig. 1). The hind femora are usually
strongly swollen and contain the metafemoral spring (Maulik 1929).
The hind tibiae are useful for generic identification.
Abdomen (Fig. 1 and Figs. 27-28)
The ventral
part of the flea beetle abdomen consists of 5 visible sternites.
The primordial first sternite has become lost in the evolution of
the Alticinae. The first visible sternite is composed of the fused
second and third true sternites. The dorsal part of the abdomen
consists of 7 membranous tergites. The 8th and the 9th segments
are telescoped within the abdomen and variously modified in the
different genders.
The male internal genitalia (Fig. 27), consisting of a penis and
significantly reduced tegmen, is one of the most important
diagnostic features for species identification.
The chitinized
structures of the female genitalia (Fig. 28) are the modified 8th and 9th abdominal
segments, but their homology and terminology is poorly known
(Lindroth 1957, Teotia 1958, Konnerth & Juga 1963, Konstantinov
1994). All tergites have preserved the plate shape, but the
sternites are represented by the highly modified vaginal palps ( =
styli in part sensu Konstantinov 1994) and tignum. The vaginal
palps are elongate sclerotized structures contained within the
vagina and attached to the inner wall of its dorsal surface. All
the structures of the female genitalia appear to be very useful
for studying intergeneric relationships and for species
identification. The spermatheca can also be used for species
identification, but only in some genera where its intraspecific
variability is fairly well known.
