264 GNATS OR MOSQUITOES — CHAPTER X amateur entomologist may be able to determine the position of any species he may take.
In the following systematic descriptions, to avoid the continual repetition of such long phrases as "first longitudinal vein," " supernumerary transverse vein," and so on, the several long veins are simply indicated by the Eoman numerals from I. to VI. respectively ; while for the transverse veins, the Arabic figures are employed, 1 meaning the humeral transverse, 2 the supernumerary, 3 the middle, and 4 the posterior transverse veins. It is also convenient to speak of the point at which a vein falls into the costa simply as its "junction," so that the three lines of printing occupied by the statement that the " auxiliary vein joins the costa at a point opposite that at which the anterior branch of the fifth longitudinal vein reaches the margin of the wing," is simply stated thus : " aux. junct. opposite post. V. junct."
In the case of banded, jointed appendages such as the palpi and legs, the statement that the bands are on the articulations will be taken to imply that the band of colour involves both the apex of the joint above, and that of the base below, in contradistinction to purely basal and apical banding, where one piece only of the appendage is involved. The use of certain other abbreviations, such as " ant." for anterior, " post." for posterior, and so on, scarcely needs detailed explanation, but their use greatly economises space in the long run, and is almost indispensable in view of the enormously increased volume of facts that must be condensed in the following pages. In addition to these, it is sometimes convenient to use the mathematical signs = for equal to, and || for parallel to, in a line with, or opposite. The distinguishing characters of the two principal subfamihes, the Anoplielina and Gulicina, in their various stages, are further illustrated in the accompanying plate, reprinted from a short paper by the author, in the Journal of the Nat. Hist. Society of Bombay.
Breiit?anq aperture^ PLATE VII.
Tiieanteriorpartsareshownin thepronepositionandthehinder endsinprofile,owingtothebody beingtwistedbythepressureof the cover glass.
/Anopheles Rossii, Giles, SarvoJ J?rea t/u7u/ t^i l^e (Culcx impellcns, WalKer, laruo) Culcx WGi«;.0'.'r.at.dei
265 CHAPTEK XI.
The Megarhinina Sub-family.
The members of this sub-family form a very natural group, which, especially in the type genus, present a general appearance which is so characteristic that its members can be recognised at a glance, once one has become familiar with a few species. They are all comparatively large insects, the smallest of them being a good deal over the average size of the family, and are generally conspicuous for their brilliant metallic colouring, of green, gold, and violet, some of them rivalling the well-known "diamond beetles" in their gorgeous reflections. The apex of the abdomen is usually broadened in appearance by a pair of large lateral, subterminal tufts of hairs, which are commonly brilliantly coloured, often in effective contrast with the hairs that fringe the end of the abdomen in the middle. Another peculiarity is that the proboscis, w^hich is always large, is bent downwards, almost into a hook. In length the palpi of the type genus resemble those of Anopheles, being as long or longer than the proboscis in both sexes, but they differ in the terminal joint being subulate, instead of club-shaped.
Although the number of species is not large they are widely distributed throughout the tropical and sub-tropical regions, and are essentially forest insects, never being found in houses. In both genera of the sub-family the nape and vertex is clothed with flat, imbricating scales only. They are distinguished from each other as follows : — Palpi long in <? , shorter in 2 ; first sub-marginal cell very small, much smaller than second posterior cell ; proboscis long, bent Sub-family Megarhin^. Palpi 5- jointed in 5 (long) Geivis,! Megarhince. PalpiS-joiutedin $ (comparatively short) Genus 2 Toxorliynchitcs. Genus I. MEGARHINA.
The original definition of this genus is sufficiently detailed to stand good, but the scale characters of the head and scutellum already mentioned are thoroughly generic, and it may be added
266 GNATS OR MOSQUITOES — CHAPTER XI that the second joint of ^ antenna has always an external lateral patch of iridescent scales. The generic characters of the venation of the wing, with its tiny ant. fork cell, are sufficiently indicated in the subjoined figure.
Fig. 39. — Typical Wing of Genus Mcfjarhina.
The following is the formal definition of the genus : — Desvoidy, "Essai sur les Culicides, Mem. Soc. d'Hist. Nat. de Paris," iii, 1827, p. 412 ; Macquart, " Diptera Exotica," vol. i, 1838, pi. i, fig. 1. (Extracted from F. A. A. Skuse. " Proc. Linn. Soc," N.S.W., 1889, p. 1720).
Proboscis bent downwards about the middle of its length ; in the male almost the length of the body, in the female a little shorter. Palpi in the male a little longer than the proboscis ; the first joint short, second, third and fourth elongate and cylindrical, of equal length, except the second, which is a little shorter ; in the female a little shorter than the proboscis with five cylindrical joints of nearly equal length. Antenna; in the male with bushy plumes, the second joint a little elongate ; in the female the joints elongate with a few long hairs at the base. Prothorax projecting from each side in the form of a scale ; bordered with hairs in the male, naked in the female. Abdomen : the three last segments bordered laterally with hairs in the male ; the copulatory organ accompanied by two appendages terminating in a point. Wings : first marginal cell very small ; transverse veins very remote from the petiolated cells.
It used to be thought that these giant mosquitoes, in spite of the alarming names of certain species, were harmless, but the information collected by Mr. Theobald during the past year shows that this is a mistake.
" It is erroneously supposed that they are not annoying to man and animals; several occasion severe irritation from their bites. Captain James, I. M.S., sends me the description of one {M. immisericors, Wlk.) which is very troublesome in India ; another comes m a collection from Mashonaland (M. lutescens, mihi), another M. speciosa) from Australia, and others have been received from New Amsterdam amongst the collections of mosquitoes sent to the Museum. They are, however, not of much importance as mosquitoes, because they are not troublesome in habitations, being entirely sylvan in habits, and thus only annoying to travellers." — (Monog.)
ON THE CLASSIFICATION OF THE FAMILY "267 In the first edition of this hand-book the descriptions of thirteen undoubted species of this genus were inckaded, and two more were placed along with them, because from their scanty descriptions as Cidices, it appeared on the whole most likely that they should really be placed here. Of the thirteen good species, one which appeared simply as " Megarhina, sp., from Sikim, has been redescribed by Mr. Theobald and reappears under the guise of M. Gilesii, Theob. ; and four more new species have been received in the museum and described by him, making the present total seventeen.
The members of this genus often present very distinct sexual differences, and this is noticeably the case with the marking of such species as have patches or bands on the tarsi, which generally differ somewhat in detail in the two sexes ; and in M'a. hamorrlioidalis, separata, and inornata, though present in the females, are quite absent in their consorts, and the same may be the case with some others which have been described from specimens of one sex only. In using the table given below, this point should be borne in mind.
Table of the Species of the Genus MEGAEHINA.
A. With the caudal tufts red and black.
II. The tarsi, with some joints marked whitish in the ? only. 1. M. hcemorrhoidalis (Fabr.) Third joint of the palpi much longer than the fourth.
2. M. separata, Arribalzaga. Third joint of the palpi as long as the fourth. Tarsi not specially described.
B. With the caudal tufts more or less yellow and black. I. The tarsi with certain joints or bands whitish, in one or both 3. M. inornata, Walker. Tarsi banded in the ? only. Thorax bronzy-brown, blue at roots of wings and on prothoracic lobes. 4. M. splendens (Wiedj. Tarsi (as in remaining cases of species with yellow and black tufts in which both sexes are known) banded in both sexes. Thorax with metallic green and gold scales. Abdomen green at base, purple behind. 5. M. i)urpiircea, Theob. Thorax chestnut with median azure line ; abdomen brilliant purple.
6. M. lutescens, Theob. Thorax dull bronze with azure patches over roots of wings ; abdomen golden-green scaled. 7. M. suhulifer, Doleschall. Thorax brown with greenish-gold scales ; anterior margin of the wing metallic-blue scaled. 8. M. speciosa, Skuse. Thorax brown with greenish scales : margin of wing pale.
268 GNATS OR MOSQUITOES — CHAPTER XI 9. M. immisericors, Walker. Thorax metallic-green ; scales on costa blackish.
10. M. Christoj^hi, Portschinsky. Thorax black with metallic -blue scales.
11. M. Gilesii, Theob. Thorax chocolate-coloured, with a greenish lustre.
12. M. rutilla, Coquillett. Thorax brown with golden and violet scales and pale yellow margins.
C. Caudal tufts steel-blue and white.
I. The tarsi with certain joints or bands whitish. 13. M. Portoricensis, Von Roder. Thorax bay, with green-gold scales.
D. Caudal tufts showing no contrasted colours, or not obviously present. I. Tarsi with certain bands or joints whitish. 14. M. Amboinensis, Doleschall. Thorax dark with glittermg golden scales ; abdomen steel-blue.
15. M. trichopyga (Wied.) Thorax black with greenish-golden scales ; abdomen brown.
16. M. ferox (Wied.) Thorax chestnut with azure inedian line ; abdomen steel-grey.
II. With the tarsi uniformly coloured in the J , adorned in the $ . 17. M. Jongipes. No distinct caudal tufts. Thorax bronze and green-scaled. Abdomen pale olive-green.
The characters on which the above table is based, and which should, therefore, be especially noted are : — (a) The colouration of the characteristic " caudal tufts." These consist of dense brushes of hairs on the sides of one or two of the last abd. segs., which are often brilliantly coloured, and may contrast in a striking manner with the similar, but somewhat shorter, hairs that densely fringe the end of the abdomen.
(h) The presence and position, or absence of pale tarsal markings. In this genus, the tarsi are rarely banded, so that these usually take the form of patches, and not of complete rings ; owing to which, they are apt to be overlooked, unless both sides of the legs are inspected.
(c) The colouration of the thorax, in connection with which, as with all colour qualifications of these brilliantly iridescent insects, it must be borne in mind that they are mostly of the sort usually spoken of as " metallic," or in other words, depend, not on pigment, or natural colour, but upon the phenomenon known as the interference of light passing through the thin plates of the scales, and which, therefore,
GENUS MEGAEHINA 269 13 12 Fig. 40. — To Illustrate the Genus Megaehina.
8 6 1, M. luEmcyrrhoidalis (Fabr.) ; 2, head of a J^ ; 3, base of antenna of M. inomata ^, Walker ; 4, one of its scales; 5, of M. ferox (Wied.) ; 6, a body scale ; 7, fore tarsal claws of «? ; 8, palpi of male — a, of M. ferox (Wied.) ; 6, of M. hcBmorrJwidalis (Fabr.) ; c, of M. separata, Arribdl. ; 9, palpus of M. purptirea, Theob. ; 10, M. ferox, head and thorax ; 11, a, venation of ? wing of the same ; b, cross veins oi ^ ; 12, toxorhynchites brevipalpis, Theoh., palpus of J ; 13, base of antenna of the same species.
270 GNATS Oil MOSQUITOES — CHAPTER XI vary according to the angle at which it falls upon them, so that the reader must be prepared to find a part described as black, appear deep violet, mauve or greenish, just as do the beautiful tail feathers of the domestic fowl : — or vice versa. This character is, of course, often noticeable in the colours of other mosquitoes, but seldom to the same extent as in these, where it is often strongly marked in the entire scaly armature.
1. MEGARHINA HiEMORRHOIDALIS (Fabr.)
Culex hcB7norrhoidalis.—'Fah., " E. S.," 401, 5; and Fab., " S. A.," 25.
Caudal tufts blood-red, with black hairs between them. Fourth joint of palpus between two and three times as long as the third. Tarsi with white markings on hind and middle legs in ? but not in c? . Third joint of palpus longer than the fourth. No fresh material has come to hand of this species, but Fabricius' desci-iption is as follows : — " Fuscous, abdomen at apex, with reddish cilia, very large for this genus (he refers to Culex), antennae very densely verticillate pilose, fuscous with the first joint nude, glistening blue ; head fuscous, glistening blue on the apex ; thorax elevated, fuscous, with anterior margin and a spot in front of the wings glistening blue ; abdomen fuscous, apex strongly rufous-ciliate ; feet blue, metallic, femora testaceous beneath ; antennae fuscous ; palpi steel-coloured ; frons and vertex gUstening emerald-green and copper ; thorax steel-grey and glistenmg green ; pleurae ferruginous ; scutellum dull yellow ; abdomen steely with ferruginous spots on either side and forming an interrupted median line, sides with silvery spots, apex with blood-red cilia ; venter sihery with yellowish tomentum ; legs steely, femora silvery below." Habitat. — South America.
2. MEGARHINA SEPARATA, Arribalzaga. '' L. A.," p. 33. Caudal tufts blood-red, with violet-black hairs between them ; legs unhanded in ^, but with second and part of third tarsal joints white in the ? . Thorax brown with fusiform metallic bronze scales, azure over the wings. Abdomen violet, purple, and coppery-red. Fourth joint of palpus equal in length to the third, otherwise differs little from preceding. Length. — 8 to 9 mm. ? to 11 S , with palpi 19 mm.
Habitat. — Para, Brazil (Walker) ; Cayenne ; Chaco in Formosa ; Argentina ; Eio de Janeiro (Lutz) ; Lower Amazon.