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This
subfamily is based on the New World genus
Collomena
Möschler, and Kitching & Rawlins (1998) included the
Iscadia
Walker generic group of Poole (1989) and, with a broader generic content,
Holloway (1998) within it. Holloway (1998) indicated that Collomena and
the allied New World genus
Motya
Walker lacked nolid features in their highly modified male genitalia. Hence
application of this family-group name within the Nolidae is contentious, and
should be assessed further when the early stages of Collomena are known.
Mell (1943) included some of the genera and Selepa Moore in his Eligmini.
The Iscadia group has several features that indicate it is monophyletic.
The tongue is sometimes reduced or vestigial (New World taxa,
Gadirtha
Walker and Plotheia
Walker). The forewing is elongate and its reniform is enlarged, with a central
patch of raised scales. The male genitalia have the uncus reduced or lost, and
the valve has a strengthened costa that often is separated to a greater or
lesser degree as a distinct process or arm. The female genitalia have a
distinctive signum consisting of a pair of adjacent (fused in Phaeothripa
Hampson) sclerotised bands running longitudinally and bearing numerous, small,
outwardly directed spines: often there is a similar but much smaller signum
opposite and somewhat displaced. The wing venation is of the groundplan type
except in Ptisciana
Walker and Phaeothripa. The labial palps in several genera (e.g.
Gadirtha, Plotheia, Triorbis Hampson and Ptisciana)
have this terminal segment long and slender, but it never exceeds the second
segment in length. There are no tymbal structures, but the
eighth tergite usually has strong apodemes or lobes.
The pupa, where known, has beading on the margin of some abdominal segments and
shivers in the cocoon, which also has stridulatory ridges on its interior
surface. In two genera (Negritothripa
Inoue and Gadirtha) the stridulatory ridges incorporate the
characteristically long larval setae (Sugi, 1987). Known larval host-plants
include a high proportion of Euphorbiaceae.
The inclusion of several Asian genera in a broad concept of Iscadia by
Poole (1989) is not followed here, as clear groupings can be recognised that
merit generic status as much as groups in other nolid subfamilies and tribes
such as the genera with ‘careine’ male genitalia in the Ariolicini and those
with a dark-scaled process to the valve in the Sarrothripini. The relationship
of Indo-Australian members of the group to New World Iscadia needs
further study. As well as the genera discussed below, the Indo-Australian
representation also includes the monotypic tropical Australian Timorodes
Meyrick and Ochthophora
Turner, with two species shared between Australia and New Guinea. Representation
of the group in Africa is not clear, but there is at least one species of
Plotheia.
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