Publ. 23. V. 1929. 
THYRIDIDAE. By Dr. A. Seitz. 
489 
20. Family: Thyridiriae. 
The relation of this family of the Heterocera to the other groups of the ,,Bombyces“ has already been 
dealt with in Vol. 2, p. 371. Particular stress had been laid there upon the fact that the Thyrididae or Siculidae 
are so closely allied to some Pyralid genera that they might be most justly reckoned among the microlepidoptera. 
Amidst the Pyralidae, the Simaethistis seem to be very near to some of their genera, but the Thyrididae are 
so very variable in their habitus that nearly each of their genera exhibits other special relations. Some small 
white species from the genus Rhodoneura (= Siculodes ) are so much like caddis-flies ( H ydrocampinae ) that they 
are only recognized as Thyrididae in the killing-bottle; this deception is effected not only by their way of flying 
but also by resting on their very thin and long legs with their wings spread. Quite different again are the Dysodia 
with their stout bodies; particularly the $$ of Dys. ignita resemble a flying forest-bug or Getonida (vid. Vol. 2, 
p. 372). 
When the 2nd volume comprising the palaearctic species was published, hardly 200 forms had been 
ascertained. Today more than 500 are known, some of which, however, are doubtfully ranged among this 
family. More than half of the forms known belong to the gigantic genus Rhodoneura in which, however, by 
reason of great neural resemblances, very heterogeneous forms have been comprised. It most clearly shows 
the entire absence of all the bifurcations in the veins of the forewings, the subcostal branches and radials arising 
separately though close together from the upper cell-angle. In this way the Thyrididae differ particularly from 
the Chrysanginae which they resemble in other respects. Above all in a great disposition to deformations of 
the wings which are often most strangely distorted. In the very beautifully coloured Risama picta Wh\, from 
Southern Brazil, and the entirely dotted Vadata macropterana Wkr. the forewing shows a vesicularly lobated 
costal margin; in Hepialodes, from Guiana, the costal margin of the hindwing is bilobate; in Draconia, from South 
America, each wing despatches two large notches at the distal margin, whilst in the Indian Camadena both wings 
are acuminate at the apices. Moreover, the wings of a great many species are most variably vitreous by hyaline 
places, from which the entire family and the typical genus derives its name (thyris=little window). 
The family itself is presumably phylogenetically old. Certain genera, such as the Herimba which were 
formerly reckoned to the Callidulidae (vid. Vol. 10, p. 491) infer connections with the latter and the Drepanidae 
which are stated to have probably developed directly from a branch of the Thyrididae. In favour of their old 
age is, above all, the geographical range extending over the whole globe and comprising not only all the continents 
but also distantly remote islands. Only in Northern Europe and various places of Central Europe the family 
seems to be altogether absent; in all the warmer regions of the Earth it is well represented. In the Ethiopian 
region one fifth of the species known have been encountered, and among them are quite a number of genera 
which are also well represented in other faunae; anyhow it is characteristic of phylogenetically old genera that 
their frequently similar species are distributed over the whole Earth through all the faunal regions. 
In the same way as the shape of the wings also the colouring and marking of the Thyrididae is frequently 
very peculiar, and nowhere do they exhibit any distinct connection with other creatures of the present epoch. 
A very strangely complicated netting, frequently with narrow meshes, covers — particularly in many South- 
American species — the whole surface of the wings and it is only interrupted by tiny hyaline spots and single 
confused lines the position and extent of which varies so much that even in large series there occur hardly two 
specimens of a species that are entirely alike in the scheme of markings, as for instance in many Rhodoneura . in 
nearly all the Draconia , and in the Striglina. In the Ethiopian fauna from which, however, almost only smaller 
forms are known, this reticulated marking is the most conspicuous in Rhodoneura eugrapha (76 e), Rh. scardialis 
(76 f), Rh. obliquifascia and others. 
XIV 
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