O. A. Johannsen.
North American Dixidae.
Psyche 30(2):52-58, 1923.

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Psyche
NORTH AMERICAN DIXIDB.
Cornell Universty, Ithaca, N. Y.
Some years ago I published a key to the species of Dixa (Bull. New York State Museum, 68:431, 1903) based largely on the color characters given in the descriptions. Through the kindness of Mr. Nathan Banks I have recently had the oppor- tunity to compare my specimens with the Loew types in the Museum of Comparative Zoology at Cambridge, and now offer a new table which includes three new species. A study of a series of specimens collected at the same time and place, having similar color characters, and an identical type of hypopyguim, therefore presumably one species, shows that the venation of the wings in this genus is subject to some variation, for which allowance must be made in identification. The length of the fork of the media is particularly variable. In one wing of one of the type specimens of D. fusca Lw. the petiole and the fork are nearly subequal in length while in the other wing of this specimen and in both wings of the second specimen the petiole is noticeably longer than the anterior branch of the fork. In D. cornuta described below, a species having a very characteristically formed clasper, the variation in the proportions is even greater.
Key to species of Dixa.
a. Costal half of the wing distinctly smoky; a dark spot at the apex of Cu 2; proboscis and scutellum yellow; knob of halteres black. D. C. . . . . . marginata Lw. aa.
Costal part of the wing not distinctly differentiated in color. b.
Tips of the hind tibiae noticeably enlarged, deep black, sharply contrasting with the remainder of the member; wing veins with clouded margins; proboscis black; hal- teres yellowish; scutellum fuscous testaceous; terminal clasper segment tapering, mesa1 process of the basal seg- ment simple, elongate.(fig. 2)Me., Mass., N.Y, clavata Lw. Pswhe 3052-58 (1923). hup Ytpsycht rinclub orgtlW30-052 html



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19231 North American Dixidce
bb.
Tips of hind tibiae not so sharply differentiated. c.
Petiole of R2+3 (measured on a straight line from its base to base of fork), less than 3/g as long as R3; pro- boscis, scutellum, and knob of the halteres yellow; crossvein of wing very feebly clouded; r-m crossvein slightly distad of the base of R4+5. N. Y., terna Lw. cc. With other characters.
d. Wing with one or more spots.
e. The space between the bases of the cubitus and anal vein, between the branches of the cubitus, and the basal part of the anallobe infuscated; terminal clasper segment triangular, mesa1 process of basal segment forked (fig. 1)) californica n. sp. ee.
With but a single, rather distinct spot on the wing. f. Petiole of R 2 + 3 and R3 subequal in length, wing spot very distinct, veins strongly marked; pro- boscis and scutellum blackish; halteres sordidly yellow; terminal clasper segment not tapering, truncate apically, mesa1 process of basal segment forked (fig 6). Me., N. Y. centralis Lw . ff.
Petiole shorter; proboscis, scutellum, and halteres yellow, N. J.; Md. . . . notata Lw.
dd.
Wing spot very indistinct or wanting.
e.
The r-m crossvein is situated slightly proximad of the base of R4+5 thus intersecting the petiole of the radial sector; Sc endsopposite the base of Rs. St. Vincent Is. f calvula Will.
ee.
The r-m crossvein is situated at or slightly distad of the base of R4+5 thus connecting this vein with the media.
f. Dorsum of the thorax yellowish with thoracic darker . stripes which may be more or less confluent; palpi dark.
g.
Proboscis yellow; scutellum and halteres black- ish; wing veins strongly marked, subcosta ends opposite to base of Rs; thoracic stripes black and more or less confluent, large part of the pleura yellow. Texas venosa Lw.




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Psyche [~~ril
gg.
Proboscis dark; s.cutellum yellowish ; wing veins not unusually pronounced; intervals between the thoracic stripes yellow.
h.
Fore basitarsus about 213 as long as the tibia; Sc ends proximad of the base of Us; knob of the halteres dark; basal segment of the clas- per of the male with a black, ventrad pro- jecting, and much curved mesal process (fig. 4). N. Y. cornuta n. sp.
hh. Fore basitarsus about 3/4 as long as the tibia. i. Apical segment of the clasper of the male fully as broad beyond the middle as at the base (fig. 3); Sc ends about opposite the base of Rs; distance between the crossveins meas- ured on the media usually not exceeding 112 the length of the m-cu crossvein. N.Y ., N- C., Cal. modesta Joh.
. .
11. Apical segment of the clasper tapering (fig.7) ; Sc ends distinctly proximad of the base of Rs; distance between the crossveins about equal to the length of the m-cu crossvein. N. Y. . simtlis n. sp.
ff. Dorsum of the thorax as well as the upper part of the pleura, black; proboscis, halteres and scutel- lum dark; Sc ends opposite the base of the radial sector. N. Y. . fusca Lw.
Dixa californica sp. nov.
Male. Head black, proboscis, palpi, and flagellum of antennae brown, basal antenna1 segments light brownish. Dorsum of the thorax and upper part of the pleura, yellow; dorsal stripes rich dark brown, nearly confluent, laterals anteriorly,
median one posteriorly abbreviated; scutellum, metanotum, and larger part of pleura brown. Abodmen black; the mesal process of the basal clasper segment forked; the apical segment in ventro-lateral aspect more or less triangular, apically with acute angle, mesally with a number of stout black setae (fig. 1).



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19231 North American Dixidoe 55
Legs yellowish brown, becoming darker towards their extremi- ties; tips of femora and of tibise darker; coxse yellow; fore barsitarsus nearly 7/8 as long as the tibia. Wings grayish hyaline, a distinct cloud covering the r-m crossvein extending up on the petiole of R2+3; space between the petiole of the cubitus and the anal vein, between the branches of the cubitus, and basal part of the anal angle more or less infuscated; veins yellowish brown; Sc ends opposite the base of Us, petiole of R2 +3 (measur- ed on a straight line from its base to base of fork) .64 as long as R3, petiole of the media measured from the crossvein 1.3 as long as MI +2, the distance between the cross veins 2/3 as long as the m-cu crossvein. Halteres brownish with yellow peduncle. Length 2.5 mm. Type in my collection. Stanford University, Cal., March.
Fig. 1. Claspers of males. Figs. 1, 3, 7 are in ventro-lateral aspect; 2, 4, 6 in ventral aspect . 1. D. califo~?zica. 2. . D. clavata. 3. D. modesta. 4. 23. cornuta. 6. D. centralis. 7. D. Sirnilis. 5. Wing of male 23. modesta. Dixa cornuta sp. nov.
Male. Head, including proboscis, palpi and antennae, brown, front shining. Thorax, including scutellum, brownish yellow, with three dull, dark brown lines, the middle one divided by a



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56 Psyche hpril
hair line, the laterals abbreviated anteriorly; metanotum and sternopleura pale brown. Abdomen blackish; the basal segment of the clasper yellow, moderately swollen, with a black, elongate, ventrad projecting and much curved mesal horn-like process; terminal segment of clasper viewed from the ventral side elon- gate as shown in fig. 4 with rows of ventro-mesa1 black spines; when viewed from the side, quadrangular, shaped somewhat like that of D. californica (fig. 1) but with the mesal angle much truncated and more spinous.
Legs brownish yellow, extreme
tips of tibiae and of tarsi darker, the hind tibiae distinctly swollen at tip; fore basitarsus about 213 as long as the corresponding tibia. Wings hyaline, very faintly cinereous, veins yellowish, crossveins not clouded; Sc ends slightly before base of Rs; petiole of R2+3 (measured on a straight line from its base to base of fork) about 0.4 as long as R3; petiole of the media measured from the crossvein, about 1.12 as long as Ml+2. Halteres dark with yellow peduncle. Length 2.5 mm. Holo- type in my collbction. McLean, N. Y. October. Female. In coloring like the male. Allotype in my collec- tion. Ithaca, N. Y. August.
Paratypes from Ithaca, N. Y., October, and from Orono, Me., June. In the Cornell University Collection and in the Museum of Comparative Zoology, Cambridge, Mass. The coloring is rather constant, except in teneral speci- mens. In the paratypes the venation is rather variable. The ratio measurement, as defined above for the radius, ranges from .36 to .50 in male specimens while the ratio measurements of the media ranges between 1.12 and 2.1.
The distance between the ,
bases of the crossveins measured along the media, is in most cases nearly equal to the length of the m-cu crossvein. The fore tibia-tarsus ratio ranges between .61 and .71, with an average of .65.
Dixa modesta Joh.
Too hastily, in the Entomological News (14:302), I de- clared this species to be the same as D. clavula Will. A careful examination of a co-type specimen of Williston's species shows



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19231 North American Dixidoe 57
modesta to be quite distinct, as indicated sufficiently in the key. To my original description may be added that Sc ends about opposite or slightly beyond, or at most but slightly proximad of the base of the radial sector (fig. 5) ; the petiole of R2 +3 (measur- ed in a straight line) is about .55 as long as R3; the petiole of the media, measured from the crossvein, about equal to M1-I-2; the distance between crossveins along the media less than 1/2 as long as the m-cu crossvein. In the western specimen there is a very faint suggestion of a cloud on the r-m crossvein. The fore basitarsus is about 314 as long as the tibia. The basal clasper segment is somewhat enlarged, mesal process short with some stout apical setae; apical segment broadest beyond the middle when viewed from the side, thence tapering to the tip; viewed more ventrally the sides are more or less parallel (fig. 3). Specimens from Ithaca N. Y., April, May; Black Mts., N. C. May; and S. Jacinto Pk., Cal., August. Type in my col- lection.
Dixa similis sp. nov.
Closely resembling D. modesta, differing chiefly in the characters given in the key.
Male. Head including proboscis, palpi, and antennae, brown; front shining. Thorax including scutellum, yellow, with three dull dark brown stripes, the middle one divided by a hair line, the laterals abbreviated anteriorly; metanotum and lower part of the pleura brown. Abdomen brown, including the glo- bose basal segment of the clasper whose mesal process is simple and provided with a few stout apical setae (fig. 7); terminal segment rather tapering when viewed more or less from the side. Legs yellow, tarsi and tips of hind tibiae a little darker; fore basitarsus about 3/4 as long as the corresponding tibia. Wings hyaline, very faintly cinereous, veins yellowish, crossvein not clouded; Sc ends in the costa at least the length of the r-m cross- vein proximad of the base of the radial sector, the distance be- tween the crossveins measured along the media about equal to the length of the m-cu cross vein; petiole of R2+3 (measured in



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58 Psyche [~~ril
a straight line from its base to the base of the fork) about .55 as long as R3; petiole of the media measured from the cross- vein about 1.25 as long as Ml+-2. Halteres yellow. lenght, 2.5 mm. Holotype in my collection. Ithaca, N. Y., August. Female. In coloring like the male. Allotype in my collec- tion. Ithaca, N. Y., August.
Paratypes collected at the same time and place in the Cornell University collection and in the Museum of Comparative Zoology at Cambridge, Mass. The radius ratio in the paratype specimens varies from .44 to .66, the media ratio from 0.8 to 1.3.



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