SOME SIAMESE TABANIDAE. 433 



Genus Tabanus, Linn. 



Hitherto, so far as it has been possible to discover, only three species of 

 Tabanus — T. rubidus, Wied., T. brunnipennis, Ric, and T. siamensis, Ric. — have 

 been recorded or described as occurring in Siam. In the following pages the number 

 of recognised Siamese species of Tabanus is raised to fourteen, namely : — 



1. Tabanus barnesi, sp. n. 8. Tabanus striatus, Fabr. 



2. ,, nigrotectus, Big. 9. ,, virgulatus, sp. n. 



3. ,, insidiator, sp. n. 10. ,, rubidus, Wied. 



4. ,, praematurus, sp. n. 11. ,, pugnax, sp. n. 



5. ,, finalis, Walk. 12. ,, pugiunculus, sp. n. 



6. ,, yubiciindulus, sp. n. 13. ,, agnoscibilis , sp. n. 



7. ,, brunnipennis, Ric. 14. ,, siamensis, Ric. 



It might be supposed, especially in view of what has been stated above with regard 

 to the two species of Haematopota mentioned, that one or more of the four species of 

 Tabanus — T. leucosparsus, T. nigrotectus {Bellardia nigrotecta), T. (Atylotus) 

 melanognathus and T. {Atylotus) laotianus — described by Bigot (Nouv. Archiv. Mus. 

 Hist. Nat., Paris (3) ii,"^pp. 203-205 (1890)) from material stated to have been 

 collected by M. Pavie in the Laos Protectorate,* French Indo-China, would be likely 

 to occur in Siam. As will be seen below, in the case at least of T. nigrotectus this 

 surmise is certainly correct. 



Of the previously described species recorded in the following pages, two at 

 least — T. striatus, Fabr., and T. rubidus, Wied. — are widely distributed in the 

 Oriental Region. On the other hand, certain species {T. barnesi, sp. n., T. insidiator, 

 sp. n., T. praematurus, sp. n.) described below appear to be closely allied to, if not 

 the representatives of, other forms which occur in the Naga and Lushai Hills, Assam, 

 so that in their cases the mountain ranges of Upper Burma would seem to form 

 an effective barrier. 



Although the subjoined Key has been tested and found sufticient for the deter- 

 mination of the extremely limited amount of material at present available to its 

 author for comparison, infallibility under all circumstances is far from being claimed 

 for it. Nevertheless, it is hoped that it may prove better than nothing, and may 

 also serve to stimulate potential collectors of Tabanids in Siam. 



Even assuming that no change in the nature of the characters employed in the 

 Key will be necessitated by the acquisition of further material, it should be noted 

 that, in the case of a given species shown in the table, these characters are only 

 sufficient to distinguish it from the other species included in the present synopsis ; 

 they are not necessarily distinctive as regards additional species of Tabanus, which 

 may ultimately prove to form part of the Siamese fauna. 



It has been necessary to confine the Key to the female sex, since, in the case 

 of the majority of the species tabulated therein, the male is at present unknown. 

 Even so, the characters given for Tabanus pugiunculus , sp. n., are perhaps incorrect, 

 since, as will be seen below (p. 453), it is not absolutely certain that the solitary 

 female provisionally assigned to that species really belongs to it. 



The number in square brackets [ ] after the name of a species indicates the serial 

 position of the species in the ensuing pages. 



Key to the Fourteen Species o/ Tabanus recorded below {Females only). 

 1 (2). Wings with first posterior cell closed and petiolate. 



{a) Scutellum smoke-grey pollinose and clothed with silvery-white hair, 

 forming a sharp colour-contrast with remainder of body ; smaller 

 species, about 15 mm. in length . . . . . . barnesi, sp n. [1] 



* In Kertesz's Cat. Dipterorum, Vol. Ill, somewhat quaintly styled the Laos Islands 

 {" Ins. Laos "). 



