Tropicomyia atomella (Malloch, 1914)
Identification of Tropicomyia species is very difficult. Many species differ only in very slight characters of the male aedeagus. Moreover, due to the insufficient availability of type material the status of several species is not fully clarified. Hence in most cases an approximation to the species can only be achieved by the comparison of pictures of the male genitalia (see also the Genus Tropicomyia) and, to some extend also the geographical range. Identification by external characters only is absolutely impossible.
T. atomella is closely related to Tropicomyia theae and Tropicomyia polyphyta and also highly similar. Because a male holotype is lacking, the taxonomic status of the present species is unclear. For this reason the species name was retained by Spencer, 1973. Additionally the larval description by Singh and Beri, 1971 provided some slight larval and puparial differences to that species referred to as theae by the authors (see below).
We don't know, if these names exactly correspond with the species concept to be inferred from the type material but they could represent real species.
IMMATURE STAGE (based on the description by Singh and Beri, 1971)
Puparium that always remains within the mine is light brown or yellow and is, as certainly also other Tropicomyia puparia, dorsoventrally flattened.
A series of characters were used by the authors to distinguish atomella from that species they identified as theae. Of these, the most distinct character for atomella is the following: Upper and lower part of dorsal arm of cephalopharyngeal skeleton posteriorly not fused. However, this character is not absolutely reliable since the appearance of the basal part of the cephalopharyngeal skeleton depends widely on the age of the material and the preparation method.
BIONOMICS
The larva produces a linear epidermal mine on the upper surface of leaves, where also the eggs are placed. Generally the mine follows the margin of the leaf. In some parts of India, Singh and Beri, 1971 observed a high abundance on various plants during August until November.
HOST PLANTS
The main host among the cultivated plants is Camellia sinensis (tea). Further host plants and host plant families are (Spencer, 1973): Nerium (Apocynaceae), Daemium (Asclepiadaceae), Combretum, Quisqualis (Combretacea), Flacourtia (Flacourtiaceae), Albizzia (Fabaceae), Gloriosa (Liliaceae), Sida (Malvaceae), Barringtonia (Myrtaceae), Bougainvillea (Nyctaginaceae), Passiflora (Passifloraceae), Murraya (Rutaceae), Wightia (Scrophulariaceae).
Spencer, 1990 (additionally): Gnetaceae, Actiniaceae, Cucurbitaceae, Styracaceae, Alangiaceae, Aquifoliaceae, Hydrangeaceae, Pittosporaceae, Asteraceae.
DISTRIBUTION
Formosa, India, Ceylon; probably Thailand (Spencer, 1973); Malaysia (Sasakawa, 1988).
ECONOMIC IMPORTANCE
No serious damage is known to be caused by Tropicomyia atomella.