*COMMENT ~ Character notes. 
 
*CHARACTER NOTES
#1. ~ (alternatively) is here used to indicate sometimes not
unreasonably included in or reduced to.
#8. Head-to-tail body length of the insect in its natural posture,
exclusive of appendages. \par{}Data (British representatives only) from
Dolling (1991). 
#10. Detectable sound production (as distinct from the often very loud
and continuous creaking of \i{}Cicadidae\i0{}) is common among
Hemiptera, although there is a paucity of properly comparative data
taxonomic data. \par{}Stridulation is known to be conducted in a variety
of ways: \par{}1. By rubbing the tip of the labium against a
cross-striated furrow in the prosternum (many \i{}Reduviidae\i0{}).
\par{}2. By rubbing wart-like, toothed tubercles in the hind tibia
against the femur (\i{}Scutelleridae\i0{}). \par{}3. By rubbing a
spinose area inside the front femur against the clypeus
(\i{}Corixidae\i0{}). \par{}4. By rubbing dorsal abdominal files against
teeth on the under-sides of the hind-wings (some \i{}Pentatomoidea\i0{},
\i{}Lygaeoidea\i0{}). \par{}5. By rubbing tubercles on the hind femura
against strigose regions on abdominal sterna (some
\i{}Pentatomoidea\i0{}). \par{}Sound is generated by Cicadidae and (less
noticeably by many other auchenorrhynchous Homoptera) not by
stridulation, but via paired tymbals at the base of the abdomen. This
phenomenon seems to be restricted to males (by contrast with sound
production by other means, as exemplified in Pentatomoidea). 
#14. Many Hemiptera (e.g., in Pentatomoidea)notoriously emit
repugnatorial fluid when alarmed, but precise taxonomic data have not
been located. 
#21. Rostrum: the piercing and sucking mouthparts (beak)
characteristic of Hemiptera. This organ comprises two pairs of
sclerotized, flexible stylets, the (external) mandibular and the
(internal) maxillary stylets, residing in a dorsal groove of the 1-4
segmented labium. 
#22. Rostrum: the piercing and sucking mouthparts (beak)
characteristic of Hemiptera. This organ comprises two pairs of
sclerotized, flexible stylets, the (external) mandibular and the
(internal) maxillary stylets, residing in a dorsal groove of the 1-4
segmented labium. 
#23. Rostrum: the piercing and sucking mouthparts (beak)
characteristic of Hemiptera. This organ comprises two pairs of
sclerotized, flexible stylets, the (external) mandibular and the
(internal) maxillary stylets, residing in a dorsal groove of the 1-4
segmented labium. 
#26. Note that the data here refer to adults - nymphs may have fewer
antennal segments. 
#33. Pronotum: the single, dorsal sclerite of the prothorax, which
is large in Heteroptera and variable in expression but often small and
collar-like in Homoptera. \par{}Prothorax: the first (anterior)
segment of the (three-segmented) thorax, which bears the front pair of
legs. \par{}Mesothorax and Metathorax: the second and third thoracic
segments, which bear the fore- and hind-wings and the mid- and
hind-legs. 
#34. Scutellum (= mesoscutellum): the dorsal posterior portion of the
mesonotum (i.e., of the visible portion of the dorsal sclerite of the
mesothorax). The literature available to me is unclear regarding the
application and/or morphological applicability of this term to
Homoptera. 
#35. The metathorax of most adult Heteroptera is routinely stated to
incorporate a large gland, which opens either by a single median
aperture on the sternum (e.g., \i{}Gerridae\i0{}), or by paired
apertures on the metapleura (i.e., laterally). These gland openings are
discussed in all the standard texts, but are used in the keys seen only
to help separate \i{}Rhopalidae\i0{} from \i{}Coreidae\i0{}. Comparative
data on their presence or absence, location and structure in other
families is hard to find, and it is not even clear whether Homoptera
exhibit metathoracic glands at all. 
#36. Tegula: a scale-like sclerite basally subtending the costa of
each fore-wing. 
#37. Immature bugs (nymphs) are wingless, and might be mistaken for
apterous or brachypterous adults. They are recognisable in having an
incomplete separation of the scutellum from the wing pads, whereas in
adults the scutellum is a separate structure. 
#39. Note that some Heteroptera have homopterous forewings, in that
their fore-wings lack the distal membrane characteristic of that
assemblage. 
#42. Clavus: in (most or all?) alate Hemiptera, a narrow
basal-posterior portion of the fore-wing (next to the scutellum) is
delimited from the corium (in Heteroptera) or from the rest of the wing
(Auchenorrhyncha) by a concave vein (the claval suture). In
Sternorrhyncha, however, the claval suture (and hence, the clavus) is
lacking in all but the Psylloidea. 
#54. Note that the data here refer to adults - nymphs may have fewer
tarsal segments.
#65. K. Kinman (Taxacom, 2015) points out that, contrary to currently
fashionable cladistic classifications which lump the traditional suborders
in an enormous, heterogeneous Hemiptera, there is strong molecular
evidence for accepting the Homoptera as a holophyletic sister group to
Heteroptera. See Nan Song \i{}et al\i0{}. (2012),
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0048778
 
