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88 BRITISH BLOOD-SUCKING FLIES BRACHYCERA—TABANIDAE 89
G e n u s TAB A X U S Linnaeus
( I n c l u d i n g - the sub-genera S::¡/i7a'yfn/s Enderlein and Ochrops Szilády.)
F r o m all parts of the world nearly two thousand species of this genus are
k n o w n , of whi ch twenty occur in this country and are discussed in the following
p a g e s . Since the first publication of " British Blood-sucking Flies " in 1906,
c h a n g e s have been made in the names and in the definitions of several species,
l a r g e l y through the work of Goffe and Colhn.
^ l o s t of the specimens then listed as Taba-mis boviuKS Linn, are no\\- reg
a r d e d as belonging to the form perplexus \'errall {ven-alH, nom. nov., see p.
I I 3 \ which was described as a variety of T. sudeticus Zeller (see A'errall, 1909,
p . 399X, but which Collin ^1932, p. 38) is " convinced must rank as a species."
S i m i l a r l y T. bis/gnatns Jaennicke is now regarded not as a var iet y of T. tropicus
^ l e i g e n , but as a separate and quite distinct species. Nearly all the lighter
s p e c i m e n s which used to be called " T. tropicus'' are now regarded as light
s p e c i m e n s of bisignatus, while the true tropicus, like bovimis, is very much
l e s s c ommo n than was formerly supposed ; it is, indeed, almost indistinguisha
b l e from T. solstitialis Aleigen.
A u s t e n ^1906, p.36; added T. borealis Aleigen to the British List from one
m a l e i^Glen Avon, Banffshire, W.R.O. Grant'). A'errall (1909, p. 366) gave
h i s opinion that this specimen was merely a male of T. vwjitanus Meigen, a
v i e w with which INIajor Aus ten ^manuscript notes) finallv concurred. Meanw
h i l e Goffe (^1931, p. 37; recorded as borealis a single female in the Hope
M u s e u m , Oxford, but Collin i^'i932, p. 37) declared that this specimen was a
n o r m a l bisignatus Jaenn. With Professor Carpenter's permission I have been
a b l e to borrow this specimen from the Hope Aluseum, and it appears to be
i n d i s t i n g u i s h a b l e from the series of T. bisignatus in the British Museum
c o l l e c t i o n . Tabanus borealis Meigen has therefore been omitted from this
v o l u m e .
A discussion of the various generic and sub-generic names in use in this
g r o u p , particularly those proposed by Enderlein (1923} has been given by Goffe
( 1 9 3 O, and is outside the scope of this volume.
KEY TO THE FEMALES OF THE BRITISH SPECIES OF Tabanus.
1. Eyes .under ordinan.- hand-lens) distinctly hairy (sub-genus Sziladynus) 2
Eyes under ordinar\- hand-lens not obviously hain," 8
NOTE.—The eyes of females of the sub-genus Ochrops may appear hairy when seen
from certain angles, but they are not obviously so.
2. Legs entirely black Tlate 22) fiiicans Meigen (p. 90)
Legs not entirely black, tibiae at least being pale at base 3
3. Frontal triangle {i.e. space immediately above antennae) bare and shining (text-fig. 2Ó and
Píate 25) turidus Fallén (p. 91)
Frontal triangle pollinose and dull ^
4. L'pper surface of abdomen black, with whitish patches, and without or with not more
than a little dull reddish colouring at sides of segments near base (Plates 23, 24) 5
Each side of first three or four abdominal segments obvieusly orange to over one-third of
width (Plate 26) 5
V \'ertex with tuft of black hairs behind ocelligerous tubercule. Abdomen sometimes with
pale lateral areas near base bisignatus Jaenn. (p. 91)
\'ertex without tuft of black hairs montanus Meig. (p. 93)
6. Reddish abdominal colouring extending more or less distinctly to segment four, which has
8.
9-
short yellow pubescence at sides (Plate 26) distinguendus \t-cx. (p. 94)
Reddish abdominal colouring not extending beyond segment three. Segment four with
black pubescence at sides _ 7
7. Hair-fringes on hind tibiae pure white for basal half. 2nd sternite entirely orange, without
black central stripe. A rather larger, inland species solstitialis Meig. (p. 95)
Hair-fringes on hind tibiae with some black hairs on whole length. 2nd sternite with
pronounced black central stripe. A rather smaller, coastal species, .tropicus Linn. (p. 96)
Large forked vein near wing tip usually with small branch at base (Plate 27) (compare also
T. luridus, T. glaucopis). Frontal calli rudimentary' or almost wanting (sub-genus
Ochrops) 9
Forked vein usually without small branch (cf. T. plebeius). Frontal calli well developed
(sub-genus Tabanus)
A small species (i i mm. or less), mouse-grey in colour with only a trace of reddish coloration
near base of abdomen. Thorax and abdomen with long greyish pubescence. Forked
vein sometimes without appendix plebeius Fallen (p. 97)
Larger species (13 mm. or more) with more or less yellowish appearance. Pubescence short,
grey or partly golden-yellow. Forked vein rarely without appendix 10
10. Ochreous species clothed with short silky golden hairs. Abdomen brownish-golden, with
conspicuous yellow side margins to first three segments fulvus Meig. (p. 98)
Yellowish-grey species, abdomen with two dark bands separated by broad ashy stripe 11
11. Greyish species. Femora yellow at tips only; frontal callus narrow and parallel-sided
rusticus Linn, (p .99)
Yellowish-grey species, abdomen distinctly yellow at sides of base ; femora yellow on apical
half ; frontal callus not parallel-sided (plate 28) nigrifacies Gobert (p. 99)
12. \>ry large species (18 mm. or more) ; abdominal segments with pale margins, and one row
of pale triangular spots in the middle ; eyes in life unhanded 13
Smaller species (10 mm.-i8 mm.) with three rows of pale abdominal spots ; eyes often
banded in life 15
13. Ground-colour of abdomen black or dark blackish brown on all segments ; median triangles
short, equilateral, not reaching front margin of segments ; ground colour of underside of
abdomen blackish or grey sudeticus Zeller (p. 100)
Base of abdomen more or less reddish-yellow in ground-colour, with black central stripe
and row of pale triangles ; underside of abdomen with some pinkish colouration towards
base 14
14. Abdomen extensively reddish yellow at sides on four or more segments ; median triangles
long, concave-sided, first three practically reaching fore-border of their segment ;
abdomen extensively pink basally below ; frontal callus as in text-fig. 37
bovi7nis\JmTi. (p. 102)
Abdomen somewhat reddish at sides, but nearly all segments blackish on front half;
triangles variable, usually like sudeticus, sometimes like bovinus ; underside of abdomen
a little pinkish or yellowish at extreme base ; frontal callus as in text-fig. 38
verralli Oldr. {perplexus Verrall) (p. 103)
15. LTpper frontal callus heart-shaped and isolated from lower one 16
LTpper frontal callus elongate and united with lower 17
16. Frontal triangle bare and shining (text-fig. 39) ; eyes in life with three purple bands
glaucopis Meig. (p. 104)
Frontal triangle pollinose, not shining (text-fig. 40) ; eyes in life unhanded
cordiger Meig. p. 105)
17. Large species (16-18 mm.) ; abdomen ver)- dark, with three very prominent rows of pale
triangles autumnalis Linn. (p. 106)
Small species (13-16 mm.) ; abdomen grey, with three rows of triangles 18