TROSIA. By Walter Hopp. 
1079 
12. Genus: Trosia Hbn. 
Trosia Hbn. (Sarothroma H. Sch., Seiathos, Edebessa Wkr., Endobrachys, Isochroma Fid., Alimera 
Mdschl., Langucys Bull., Tboscora Schs.) is characterized by the little pigeon shape of the appendage of the 
10th male ventral segment, produced by the coalescence of the uncus with the socii into an azygous body, co¬ 
vered by a thin skin with a structure of tactile hollows, only the extreme end being sometimes bare. As in the 
13th genus Macara, the socii are situate ventrally to the uncus. Brightly coloured species which are only rarely 
white owing to a loss of the pigment, often with characteristic markings. But the colourings and markings fre¬ 
quently form transitions to each other, and the species are partly more closely allied than in other genera. For 
the usual distinctive mark of the the shape of the sexual armature, is not always suitable here for deter¬ 
mining the species. Only few species can be safely separated in this way; the organization of the sexual arma¬ 
ture is the same in nearly all the species, and smaller differences in the shape of the stout or slender uncus, of 
the glandular-lobate, hairy sacculi, the shelled slender harpes, the cornuti etc., prove to be inconstant. Besides 
some species exhibit a great variability of size, colouring and marking, though they are not exactly races. Ex¬ 
treme forms appear to be confined to certain localities, but the same tendency of variation occurs in distantly 
remote parts of Central and South America. The way the colourings have developed as pigmenting stages can 
often be recognized: black is replaced by red, red by orange, orange by yellow, yellow fades into white. On 
the other hand, however, also dark brown pigments occur as new formations, and besides reddish ochreous pig¬ 
ments are covered by black owing to certain climatic conditions (in alpine districts or rainy forests). Also other 
morphological details, such as the length of the hair, the wing-contours, are only average distinctive marks for 
the species. Distinct morphological differences between the real species, as far as they have been explored, are 
present in the female genitals, but tbev cannot yet be described to-day, especially since the 99 of many species 
and forms are not yet known. 
1. Edebessa- group. 
In many respects the Edebessa- species are the most generalized of the genus. They are relatively large 
and show especially bright colours and markings. The 10th male ventral segment is broader and flatter than 
in the other species and sometimes exhibits yet dorsally at the end a middle seam as a rudiment of former 
pairedness. 
T. nigropuncta Drc. (160 c) unites on the wings the markings of the other species of the group, but it nigro- 
seems to be little variable. It has a black abdomen, a red mesothorax, a black prothorax and head, and black vuncia. 
legs. All the black is more or less dusted over with leaden grey. The width of the forewings is rather variable. 
Peru, Ecuador, Colombia. 
T. nigrorufa Wkr. (= obusta Dogn.) (160 c) has a black head, thorax and 1st ventral segment, dusted nigroruja. 
with leaden grey, a light vermilion abdomen, black legs, sometimes with small white or red parts. The marking 
of the wings is variable; the large black parts are broken up into smaller spots and streaks, the red places become 
ring-shaped or moon-shaped. Extreme such forms are: 
T. bicolor Mschlr. (= languciata Sehs.) (160 c) both in the <J and 9- nigroruja and its transitions are bicolor. 
known from Peru, Ecuador, Colombia, the Amazons and Guiana, bicolor hitherto only from Guiana. 
T. circumcincta Schs. (160 d) has a black head, thorax and 1st abdominal segment dusted with leaden circum- 
grey, the rest of the abdomen is light vermilion above, black beneath. Femora and tibiae outside red. inside cmcia - 
black, tarsi red. These marks are noteworthy, especially for the distinction of the 9$ of circumcincta and parens , 
which are otherwise sometimes very similar. - - purens Wkr. (160 d) has a red head and thorax, the prothorax purens. 
with a dorsal saddle which is dusted with whitish grey, similar lateral spots on the mesothorax and a dorsal 
one on the metathorax. The legs are red, with scanty whitish hairs. Abdomen red also beneath; also the 1st 
ventral segment is red above, circumcincta is hitherto only known from Guiana, purens from Rio de Janeiro, 
Minas Geraes, Paraguay, the Lower x4mazons, and Guiana. 
2. Revocans- group. 
T. revocans Fldr. (160 d) (described as Endobrachys) is allied to the dimas- group in spite of the different revocans. 
scheme of markings; its male sexual armature can be hardly distinguished from that group. The name is due 
to a figure of the 9 from French Guiana, by which Kirb v y was induced to regard the species as a Notodontida, 
Synonymous are jeanette Dyar from French Guiana and arpi Schs. (ferugina Jones) from Rio de Janeiro; the 
differences of colour, according to which the latter were named, vary individually, though in South Brazil 
the yellow tints may be more common and the grey tints of the hindwings frequently more reduced than in 
