Chales W. Johnson.
Note on the Species of the Genus Acrocera.
Psyche 22:198-202, 1915.

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198 Psyche [December
EXPLANATION OF PLATE.
Fig. 1. Egg.
1. 2. Egg-mass.
3. Longitudinal section of stem showing position of egg at base of old bud scale.
4. First instar.
5. Second instar.
6. Third instar.
7. Fourth instar.
8. Fifth instar.
9. Adult female.
10. Adult male.
NOTE ON THE SPECIES OF THE GENUS ACROCERA. BY CHARLES W. JOHNSON,
Boston Society of National History, Boston, Mass. Most of the species of this genus have remained practically unknown since they were described. This is undoubtedly due to poor description on the one hand and to the scarcity of material on the other. Since obtaining my first specimen in 1895, only seventeen additional specimens have come under my observation, representing perhaps seven species. The variable and vestigial character of the venation offers an attractive field for study if only sufficient material could be obtained. The species, so far as known, parasitize the ground spiders of the genera Lycosa and Amauro- bius, and no doubt a number could be obtained by raising the various species of spiders of these genera. The late Dr. T. H. Montgomery in conducting some studies on the Lycosids, bred a number of Acroceraj'asciata, and I remember he said that he could detect those which were parasitized, long before there was any other indication, by their weaker and more poorly constructed webs, the parasite evidently affecting the functions of the spinneret. The brief Latin descriptions by Westwood (Trans. Ent. Soc., London, V, 91, 1848), are very trying, and the positive identifica- tion of some of his species seems almost impossible with so little material, especially from the southern states-three of his species being described from Georgia. I can therefore present only the following provisional table and notes, trusting that they may lead to a further study of this interesting genus:



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PSYCHE, 1915.
VOL. XXII. PLATE XVII.




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19151
Johnson-Note on the Species of the Genus Acrocera Dorsum of the thorax marked with yellow.. ........................... 2
Dorsum of the thorax entirely black. ... : ............................. 3
Thorax with two elongated spots or stripes (Wash.). .......... liturata Will. Thorax with two cuneiform markings (N. Y., N. H.) ...... subfasciata Westw. Venation typical (N. Y., Mass., Me.). ...................... .bulls Westw. Venation not typical.. ............................................. 4 Second longitudinal vein wanting. ................................... 5 Second longitudinal vein rudimentary, present only at the apex (D. C., Pa., Que,, Mass.) ..................................... biimaculata Loew Third longitudinal vein branched and the anterior cross vein present ..... 6 Third longitudinal vein with the branch and the anterior cross vein obso- leteorwanting .................................................. 7 Abdomen with a complete uninterrupted fascia on all the segments (Ga., Pa., Ill., Mass.) ........................................ fasciata Wied. Abdomen with irregular maculation on the third and fourth segments (Ga., ...................................
Conn., Vt., N. H.) .nigrina Westw.
Abdomen yellow, except at the very base; veins extremely light (Wis., Me.) obsoleta V. d. Wulp
...... Abdomen black, wings fuscous at the base (Ga.) .fumipennis Westw.
Abdomen yellow, base of the segments black; wings hyaline (Ga., Md., Pa., ........................................... Wis.) .unguiculata Westw.
Acrocera subfasciata Westwood. Figure 1. A specimen collected by J. C. Bridwell at Pelham, N. H., Sep- tember 8, 1905, agrees well with Westwood's description, except that the yellow cuneiform markings on each side of the anterior part of the thorax extend in two very narrow subdorsal lines to the base of the scutellum, a likely variation, apparently resembling A. liturata Will., which may prove to be an extreme variation. The abdomen is yellow with dorsal and lateral spots of black, those on the second segment narrowly connected with those on the sides. Venation typical. As Westwood lays considerable stress on obso- lete veins and Williston does not mention the venation of A. liturata, I take it for granted that both are typical in this respect. Acrocera bulla Westwood.
Again I take it for granted that Westwood's species has typical venation. A specimen collected at Bailey's Island, Me., August 20, 1915, by Dr. G. M. Allen agrees well with the description. The specimen referred to has very light yellow markings, those on the second segment consisting of two widely separated triangular spots on the posterior margin; the third segment



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200 Psyche [December
similarly marked, except that the spots are quadrate and very narrowly separated at the posterior margin; fourth seg- ment largely yellow, with a dorsal triangle and small triangles at the anterior angles, black; venter black, with narrow white posterior maxgins on all the segments. Legs a very light yellow, last joint of the tarsi and the claw black, halteres yellow. Length, 4.5 mm.
Fig. 1
Fig. 3
Fig. 2
Fig. 4
A second specimen collected by Stanley W. Bromley, at South- bridge, Mass., has dark yellow markings, the two widely separated spots on the second segment are quadrate, those on the third triangular and narrowly connected, and those on the fourth quad- rate and also narrowly connected at the posterior margin. The wings and squamae are a slightly darker hyaline than the Maine specimen. It is also more robust but measures about the same in length owing to a slight contraction of the abdomen. A third specimen in the Museum of Comparative Zoology, from Maine (Osten Sacken), has the markings on the abdomen reduced in size, those on the second segment consisting of two small spots, while those on the third are somewhat larger and widely separated. Acrocera birnaculata Loew. Figure 2.
This species is most readily recognized by its rudimentary second longitudinal vein, as the markings on the abdomen are somewhat variable. A specimen from Levis Co., Quebec (G. Chagnon), agrees with the type in having two large maculations on the posterior margin of the fourth segment. A specimen collected by Mr. C. A. Voelker at Clifton, Delaware Co., Pa., has two additional



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19151 Johnson-Note on the Species of the Genus Acrocera 201 small spots on the posterior margin of the third segment. A third
specimen, collected by Stanley W. Bromley at Southbridge, Mass., June 25, 1915, represents a small male, with only a margin of yel- low at the posterior angle of the fourth segment. The wings are
light hyaline. Length, 4 to 6 mm.
Acrocera fasciata Wiedemann. Figure 3.
This is the best known species.
It has been bred from Lycos
ocreata Hentz (L. stonei Montg.) near Philadelphia, Pa., by Dr. T. H. Montgomery (PSYCHE, XI, 17,1904) and by Mr. J. H. Emerton from Amaurbius qlvestris at Waltham (PSYCHE, V. 404, 1890). A specimen collected by Mr. C. A. Frost at Framingham, June 9, 1915, represents a small male, 3 mm. in length. The scutellum is black except the apex, and the wings are a clear not a brownish hyaline. The uninterrupted bands on all of the segments readily distinguish the species. The female measures 5 mm. and has the scutellum entirely yellow. The wing figured shows an adventi- tous cross vein between the forks of the third vein, present on the left wing of one specimen.
Acrocera nigrina Westwood.
I am referring to this species four specimens which show some variation in the abdominal markings but no more than would probably exist in a large series. One has two large spots on the third segment, very narrowly connected on the posterior margin. The other three have small irregular spots. In all of the specimens the fourth segment is largely light yellow. Legs yellow, femora and tibise obscurely brown on the middle third; sqnamse margined with brown; wings pale brown, the second longitudinal vein want- ing, a character probably overlooked by Westwood. The speci- mens measure from 4 to 5 mm.
These four examples are from the following localities : Darien, Conn., June 12, and Bennington, Vt., June 18, 1915 (C. W. John- son); Shirley Hill, N. H., June 17, 1911 (F. W. Grigg); Quebec (Provancher) Museum of Comparative Zoology. The latter has the usual abdominal markings, but the second longitudinal vein is indicated by a short stub at the base and by two short, inter- rupted dashes on one wing and one on the other midway between the base and where the apex should be.
The entire absence of




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202 Psyche [December
yellow markings on the second segment would indicate that it belongs here rather than to A. bulla, while the great amount of yellow on both the third and fourth segments bars it from A. bimaculata. This characteristic suggests, however, that bulla, bimaculata and nigrina may possibly represent extreme variations of one species, but much more material would be necessary to prove this.
Acrocera obsoleta Van der Wulp.
A. obsoleta V. d. Wulp.
Tijdschr. v. Ent., 11, 2nd. ser., p. 139 pi. 3, f. 17, 1867. A specimen which I am referring to this species was taken by Mr. A. P. Morse at Orona, Me., August 5, 1915. The abdomen is
bright yellow except for a narrow basal margin, a dorsal triangle at the base of the third segment, and a small anal spot of black; venter yellow, segment with narrow, whitish, posterior margins and la,teral spots of black. Wings whitish hyaline, with very pale veins, giving them an obsolete appearance. Length, 5.5. Van der Wulp in figuring the wing indicates all but the auxil- iary and first longitudinal veins by dotted lines; " alarum nervis, prseter nervos longitudinales duos priores obsoletissimis; furca in apice petiolo breviori," would, however, indicate that they were present and all are shown except the second longitudinal vein. The branch of the third longitudinal vein and anterior cross vein are the first to disappear as in the case of A. unguiculata. Acrocera unguiculata Westwood. Figure 4. I am referring to this species two specimens which have two important characters in common, i. e., the branch of the third vein and the anterior cross vein are wanting. The smaller specimen
which was taken at Fort Washington, Md., May 26,1895, measures 3 mm. in length. The third segment has a large, yellow, transverse spot on the posterior half, not reaching the lateral margins; the fourth segment is yellow except for a narrow anterior margin.
Wings whitish hyaline.
The larger specimen measuring 5 mm.,
was collected at Lehigh Gap, Pa., July 10, 1897 (H. 1,. Viereck). The yellow on the abdomen covers all of the fourth, all but a nar- row anterior margin on the third, and the posterior dorsal fourth, of the second segment. The wings are brownish hyaline. The abdominal markings agree fairly well with Westwood's description



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