A. A. Girault and G. E. Sanders.
The Chalcidoid Parasites of the Common House or Typhoid Fly and Its Allies.
Psyche 17:108-117, 1910.

Full text (searchable PDF, 920K)
Durable link: http://psyche.entclub.org/17/17-108.html

The following unprocessed text is extracted from the PDF file, and is likely to be both incomplete and full of errors. Please consult the PDF file for the complete article.

108 Psyche [June
THE CHALCIDOID PARASITES OF THE COMMON
HOUSE OR TYPHOID FLY (MUSCA DOMESTICA
LINN.) AND ITS ALL1ES.l
11. RECONSTRUCTION OF THE GENUS Pachycrepoidews ASHMEAD OF THE FAMILY PTEROMAIIDAE, WITH DESCRIPTIOX OF P. DuhWs ASHMEAD, SP. Nov., ITS TYPE SPECIES.
The University of Illinois.
Introduction.
This second of the series of papers on the chalcidoid parasites of the house fly and its allies considers a monotypical genus which occurred but rarely in connection with its host. We met with it but four or five times during the course of our rearing work and are not perfectly sure as to its role as a parasite. The tribe to which it belongs is composed of genera supposed to be mostly hyperparasitic, but at the present state of our knowledge of the host relations of the group, this is no reason for classing the genus as the same. Our records lead us to believe that it attacks Musca domestics as a primary parasite, with the possible alternative of being secondary, its host Muscidifurax raptor Girault and Sanders MS.' or one of the species of Spalangia, also to be considered later. History and Description of the Genus.
In a table of the genera of the Sphegigasterine tribe Pachyneu- rini published in 1904, Ashmead, in his memoir on the classification of the chalcid flies, briefly described the genus under consideration, merely naming the species Pachycrepoideus dubius Ashmead as type, without describing the species or even indicating that it was new to science. The genus was proposed as follows: "Table of Genera.
1. Females .......................................................... 2 Males ............................................................. 7 2. Mesothoracic furrows distinct, complete.. ........................ .3 Mesothoracic furrows incomplete, indicated only anteriorly. ........ .! Continued from Vol. XVII, p. 28.
a Described in the third paper of this series.



================================================================================

19101 Girault and Sanders - Chalcidoid Parasites 109 3.
Stigmal vein with a large knob; abdomen ovate, pointed at apex, the second segment large, the third segment very short, the fourth and fifth rather large, sub-equal, the following very short. Pachycrepis Fdrster (type Curuna clavata Walk.) Stigmal vein with a small knob; abdomen ovale, the second and third segments large, the fourth and fifth very short, the sixth and seventh longer.
Pachycrepoideus Ashmead, g. nov. (type P. dubius Ashm.) 4.
Abdomen above flat or depressed.. ................................ .5 Abdomen above convexly rounded.. ............................... .6 5." Etc., p. 329.
Extracting, the genus was described thus, including both sexes: Pteromalids with the abdomen distinctly petiolate; fore wings with the marginal vein not especially long but thick and stout; cephalic aspect of head short and rounded, the occipital line incomplete; antennae inserted on or near the middle of the face, far above the clypeus; mesothoracic furrows distinct, complete; stigma1 vein with a small knob; abdomen ovate, the second and third segments large, the fourth and fifth very short, the sixth and seventh longer. It is only through the kindness of Mr. J. C. Crawford of the United States National Museum, who compared our specimens with the single type specimen of the genus, that we were able to establish their identity. The existing codes of nomenclature do not clearly cover this case. As a matter of principle, we are greatly opposed to accepting genera belonging to this class, especially those of recent description, believing them to be obstructions; the species is a nomen nudum, for in this case it is obvious that the generic de- scription does not include the species or have reference to any specific characters; it cannot be, therefore, in any sense an indica- tion, definition, or description for the species. Hence, it is our opinion that all genera and species of this class are without status in nomenclature, the many opinions and the codes to the contrary notwithstanding. Accepting this fact, the genus Pachycrepoideus and its type species is subject to arbitrary treatment at the hands of the first systematist who happens to deal with it. We have nothing to do here with so-called credit or with courtesy, but solely with expediency and nomenclatorial science, which is impersonal. So we protest, not against this genus alone, but against all of the genera of its class, irrespective of authorship ; as we protested



================================================================================

110 Psyche [June
against Nasonia Ashmead in the first paper of this series. At the
present day, the formation of genera in this manner is both obstruc- tive and inexcusable; it should be prevented. Recognizing expediency alone in this case, we are of the opinion that both the generic and the specific name should be retained on the basis of reconstruction and that in order to avoid confusion, the Fig. 1. Antenna of Pachycrepoideus dubius Ashm., and right and left mandibles showing dentition.
original author of the names should be cited. We therefore retain
the name Pachycrepoideus dubius Ashmead with the single female specimen, upon which the genus was founded as type. Type: P. dubius Ashmead sp. nov.
Female.
Normal in size and aspect for the tribe; submetallic, reticulated. Head (cephalic aspect) circularly triangular, slightly wider than long; clypeus slightly wider than long, its apical margin slightly emarginate at the meson, the whole margin trisinuate; dorsal aspect, head wider than the thorax, the vertex broad and rounded, the occipital margin broadly concave but the vertex not noticeably narrowed at the meson, the ocelli in a flat triangle in the center of the vertex, distant from the margin of the eyes; latral aspect, gense rounded, as long as the rounded-ovate eyes, the genal sulcus absent. Antennae inserted about two thirds down the face, slightly ventrad of an imaginary line drawn between the ventral ends of the eyes, the flagellum clavate; antennae 13-jointed, with three ring-joints (see fig.) and a 3-jointed club, the pedicel long, distinctly longer than the moderately long first funicle joint (Fig. 1).
Pronoturn distinct, transverse, narrower than the mesothorax; parapsidal



================================================================================

19101 Girault aud Sanders - Chalcidoid Parasites Ill furrows distinct, complete; axilla; widely separated, extending mesad to the parapsidd furrows; scutellum normal, rounded; metatborax moderate in length, shorter than the scutellum, declivous, the pro- and mesonotum flat, the metanotum punctate, with complete lateral carinse, without spiracular auici and with no tree median farina but with a distinct, subaeute rotundity at its base medially; its spiracle moderately large, subrmiforma; no meta- thoracic neck. Abdomen with a moderate petiole, variable in shape, usually ovate and depressed, concave dorsad, flatly convex ventrad, with a slight ridge along the venter at the meson; rarely compressed and conic-ovate, flat dorsad, very convex ventrad but not long; second and third abdominal segments large, united forming about half the length of the abdomen (ex- cluding petiole), the fourth and fifth segments subequal, much smaller ; abdomen about equal in length to the thorax. Wings normal, hyaline, the short and broad marginal vein subequal to the clavate sti&al vein and a fourth shorter than the narrow post-mar+ nal vein; hind wings uniformly ciliate discally. Knob of siigmal vein small.
Tarsi b-jointed, all tibia1 spurs single. Mandibles 3 and &dentate (Fig. 9). Maxillary palpi &jointed, the distal joint largest, labial palpi 3-jointed, the middle joint smallest, the others subequal. Hale. The same, but the antenna are cylindrical and inserted nearer to the middle of the face, the gem1 sulc-us present, the abdomen obconic and aepressed and more or less truncate at the caudal end. The genus cannot be confused with any other of the tribe Pachy- neurim, excepting PacJtycrepis Forster, the complete, distinct mcaoilioxacic furrows distmguiahing it. From Pwhycrepis it dif- fers in the smaller stigma! knob and the abdominal characters brought out in the quoted portion of Ashmead's table given previously.
No locality for the type species has been recorded in the litera- tore, but the single type specimen now in the United States Na- tional Museum formerly bore the number 602 of C, F. Baker, Agricultural College, Michigan. We have found it only at Cham- paign, Illinois.
Our knowledge concerning the host relations of the genus is too scanty for positive statement. As shown on a later page, the single species was reared always in connection with Musca domedica, and in four of the six rearing records it was definitely connected with that host of which it appears to be a primary parasite. Muscidi-
fwax Girault and Sanders MS. and Spalangia Latreille are com- mon primary parasites of the home fly, and in one instance each was



================================================================================

112 Psyche [June
reared in numbers in connection with this species from the same host lot. In several of the host puparia in other lots from which P. dubius emerged (single specimens) there was found in each the blackened, compact meconium of the parasite, somewhat similar to that of Spalangia and Muscidifurax, as well as the remains of a pupa of Musca, which fact indicates primary parasitism. The evi- dence available, therefore, points to Musca dornestica as the host of this species, which we consider as a solitary, external parasite with habits similar to those of Muscidifurax and Spalangia. Pachycrepoideus dubius Ashm. sp. nov.
Ashmead, Mem. Carnegie Mus., I, pp. 329, 383 (1904). .
Female. Length variable, 1.45-2.10 mm. Normal for the tribe. Gen- eral color nigroseneous, black with slight aeneous reflections, submetallic but in bright sunlight metallic dark-greenish, the abdomen smooth and shining, polished black, like surface of tar, the head and thorax closely retic- ulated or confluently punctate, reflective, somewhat glossy and sparsely hispid; antennae concolorous but not metallic, the scape, pedicel and first two ring-joints variable, usually fuscous, the pedicel dusky dorsad; cox= concolorous, the cephalic and intermediate coxae more diluted in color, the posterior cox= metallic; legs variable, uniformly fuscous, with the apical tarsal joint dusky or black, or else fuscous with more or less blackish in the dorsal aspect of the femur or the whole femur distinctly darker than the following joints; tegulae fuscous; wings hyaline, venation neutral black, the marginal vein conspicuous. Eyes inconspicuous in color, dark garnet, the middle longitudinal third much darker, forming a dark median longitudinal stripe; ocelli liquid pinkish. Venter concolorous. Clothing of body in- conspicuous.
(Cephalic aspect) head sub-circular, circularly triangular, slightly wider than long, face with a median impression along the scrobes, the scapes lying side by side in the impression and extending not quite to the cephalic margin of the vertex or to the dorsal apex of the eyes and less near to the cephalic ocellus; clypeus slightly wider than long, slightly emarginate at the meson of its apical (ventral) margin, its basal or proximal (dorsal) margin slightly convex, its
sutures obsolete, but the whole sclerite slightly im- pressed and finely, longitudinally striate; antennae inserted nearly two thirds down (ventrad) the face, slightly below (ventrad) an imaginary line drawn between the ventral ends of the eyes, but not especially near the clypeus, being slightly more the distance above (dorsad) that sclerite as the latter is long at the median line; (lateral aspect) genal sulcus absent; the cheeks rounded and as long as the length of the eyes; the latter rounded- ovate, longer than wide, with sparse, minute setse, practically naked, their



================================================================================

19101 iitrault and SaadertÌÔChalcidoi Parafltes 118 surface about: equal in roughness to the general sculpture of the head; face declivous ventrad from the insertion of the antenna; (dorsal aspect) head twice wider than long, wider than the greatest width of the thorax, the vertex broad, its. cephalic margin straight and rounded, the occipital margin rounded, concavdy cud, the visible portions of the margins of the eves regularly convex, entire; portions of the head caudad of the eyes narrow but not acute or sharp; lateral ocelli narrow or hear-ovate, the cephalic ocellua circular; each lateral odlns slightly farther from the te- ~pective eye margin than from the cephalic wellus and a third farther apart from each other than each is from the cephalic ocetlus. Occipital foramind hpre~ion tounded.
(Dorsal aspect) pronoturn visible, distincb not as wide as the mesonotum and about a fourth its length, not narrowed at the meson, its margins straight and rounded, obtuse; pro- and mesonobun practically flat, slightly convex
(lateral aspect, viewed in outline), the thorax declivous at the mesopostscutdlum; parapsidal furrows distinct, complete, narrow, con- vexly curved; cephalic margin of the mesoscutmn straighti its caudal margin broadly convex; axillae, with their mesa1 apices or angles, reaching to the base of the respective parapsidal furrow, the suture separating them from the scutellum widening caudad and with a few transverse ridges; scutduin broadly rounded caudad, nearly as long as the inesoseutuin, with a, Mat cross-furrow before apex; mesopostscutellurn narrow; metathorax moderate in length, not quite as long as the scutellnm, tteclivous, punctate, bicarinate, without a spiracular sulcus, the spiracle moderately large, sub- renifom (Unear and slightly cud), lying in an oblique position and with its cophalo-mesd end near the lateral carina and not distant from the meso- po~lscukllum; disk of the Baetathii~ax, or portion Included between the lateral carinse, produced, farther caudad than the lateral portions of the segment, its lateral angles subacute; neck absent; folds or lateral carina distinct, complete, running mudo-mesad in a gently curving line; median carina absent, but at the base of the metathorax at the meson and against the mesopostscutelhim is a distinct, subacute rotundity, best seen from the direct lateral aspect. Thorax moderately, confluently punctate, or coarsely reticulated, the sculpture slightly coarser than that of the head, and still more coarse on the dish of the metanoh Thoracic pleura simOari~ sculptured, as are also the posterior coxte; anterior coxte reticulated, the intenmediate coxse nearly smooth.
Abdomen distinctly petiolate, the petiole moderate in length; the tip of the ovipositor slightly exserted ; ventral valves inconspicuous ; segments two and three aiibequal, lone, the second longer, both taken together occupying half the surface, the fourth and fifth segments subeqnd, short, each about a half the length of either the second or third segment^; caudal margins of the second and third segments in the dorad aspect straight, in the lateral aspect curved convexly and in the ventral aspect bilobed, incised at the meson; remaining abdominal segments inconspicuous, the apical segment acute. Wings normal for the tribe, that portion of the fore wing distad



================================================================================

Psyche
[June
of the submarginal vein closely ciiiate, the remaining proximal part mostly naked, the marginal cilia of fore wing short and close, absent prorimad on both margins; marginal vein abnormally broadened as in Pachyn̤uro' Walker, conspicuous, about thrice the width of the postmarginal vein, short and broad, about the length of the stigma1 vein and about a fourth shorter than the slender postmarginal vein; snbmarginal vein narrow, widening at distal sixth at its carve before joining the marginal win and more than four times longer than the latter, much slenderer and bearing about fifteen large bristles from its surface; stigrod vein shorter than the post- marginal vein, straight, elevate, and with a small UDCUS, its hob or club distinct but not formed abruptly; postmarginal vein long and slender, mi- form in width, distinctly longer than either the marginal or stigma1 veins, being about a fourth longer than either; marginal cilia of the costal margin of Hie wing beginning at the proidma1 end of the marginal vein; fore wing broadly rounded at the apex, the wing being widest at a point slight1~ ahtad of the end of the poshnarginal vein; several spurious veins present. Hind wings uniformly, but not densely, ciliate on the disk, the submarginal vein extending to the booklets; the costal cell irregular in shape, dilated in the middle, the ~uhoaarginal vein consisting of a moderately broad prori- ma1 half, confluent, or nearly, with the costal margin, then an abrupt nar- row portion not aa long as the proximal thickened half and curving caudad away from the costal margin, the costal cell distinct and moderately broad at that point, and finally a third, short curved part distad, as broad as the proximal half and carved latero-cephalad to join the marginal vein at the booklets and uniform in width with the marginal vein; mb- marginal vein about one and a half tirocs longer than the marginal vein; posterior wings broadest at a point just distad of the apical end of the marginal vein, that is to say, a short distance &tad of the praxtmal half of the wing; apex subacute; marginal dlla longer, sparser, longest on the caudal margin of the distal half or third of the wing. Tarsi 5-jointed, the tibia1 spurs all single.
Antenna consisting of a scape, pedicel, three ring-joints, five funicle joints and three dub joints; funide and club hispid-pubescent, the flagel- lum regularly clavate, the chib not abruptly formed or much larger or wider than the funide. Scape long, cylindrical, slightly tapering distad, more than half the length of the flagdlwn and longer than the funiele, snbeqnd in length to the united length of the pedicel, three ring-joints and the first three fmide joints; pedicel chronic, conspicuously longer than the third ring-joint and equal in length to it and the first funicle joint combined; the two proximal ring-joints distinct, equal, combined slightly longer than the third ring-joint, the latter abruptly smaller than the first fnnicle joint, a large ring-joint, nearly twice the size of either of the other ring-joints. and not bare like them. but only a third the length of the fot- lowing joint and about a. fourth the length of the pedicel, wider than long; funicle joints cylihdrical, but gradually becoming shorter, so that the



================================================================================

19101 Gt~auIt and Sander* - Chdcidoid Parasites 116 fourth and fifth are subquadrate and subequal, the second and third sub- equa.1, longer than wide and the first the longest joint of the funlcle, about a third longer than the fourth or fifth; the basal joint of the dub sub- quadrate but slightly longer and wider than the fourth or fifth fdde joints; the intermediate joint wider than long, and the apical joint obtusely conical, slightly larger than the third ring-joint:; %it a single row of hispid hairs on each joint of the funicle and club, in baltam mounts of anten- nas appearing aa white longitudinal ridges (Fig, 1). Mandibles 3- (left) and 4-dentate (right), in the former case, the inner mesal tooth is truncate and shortest, the two others acute, the lateral tooth longest; in the latter cafe, the three inner (mesal) teeth small, obtuse and subequal, the lateral outer tooth much longer, obtusely conic (Fig. 3). From fourteen specimens.
SIah. Length, variable, averaging 1.60 mm. The same, more asceous metallic, the sculpture coarser, the body more slender, the aoteimee pilose- pubescent, inserted nearer to the middle of the face, distinctly above
(dorsad) of an imaginary line drawn between the ventral ends of the eyes, but not half way up the eye margins, the face more convex; antenna! strobes deep, margined, running vertically nearly to the cephalic ocellus aad nearly confluent at the meson, the medial impression not as noticeable as in the female; gend sdcus present, but very faint, narrow; the abdomen more distinctly petiolate and depressed, obconic, broadly truncate caudad, the second segment longest, covering two thirds of the surface, the ab- domen widest at its apex, the third segment about a half shorter and the remaining ones hidden within; genitalia exserted in death; abdomen, in- cluding the petiole, not quite as long as the thorax, slightly concave dorsad, slightly convex ventrad; petiole not coarsely rugose. Antennae the same in general, but more slender, the flagellum cylindrical; dub somewhat narrower than the funide, the scape slightly curved, not tapering distad, cylindrical) not as hag in proportion to the flagellnm, less than half its length and not quite as long as the funide; pedicel large but not as long as the united lengths of the third ring-joint and first funi- cie joint; the proxitnal ring-joint smaller than the intermediate one; all funicle joints longer than wide and subequal; the third ring-joint is sub- quadrate, yet longer than wide and about half the length of any one of the funicle joints and longer than the united lengths of the two prosdroal ring- joints; first funiele joint not noticeably longer than the fifth; club cytindri- cal, its first two joints subequal, longer than wide, somewhat shorter than funide five, the apical joint conical, a fourth shorter than the basal joints. At least three rows of pilose hairs on funicle joints one to five and the three club joints and two rows on the third ring-joint; a few short hairs on the dorsal aspect of the pedicel, the two proxfrnal ring-joints and scape naked. Mandibles as in the female; the distal joint of the maxillary palpi twice longer than any of the three remaining joints, which are all subequal and



================================================================================

116 Psyche [June
moderately short; the distal joint of the maxillary palpi clavate and hairy at its tips.
Described from eight males and fourteen females, unless other- wise stated, now in thg collections of the Illinois State Laboratory of Natural History, Urbana, Illinois, and reared in the insectary of the office of the State Entomologist of Illinois, at Urbana during the late summer of 1908, from the following experiments: (1) One female appeared Sept. 11, 1908, in company with two females of Nasonia brevicornis Ashmead from decomposed chicken entrails infested with dipterous maggots, taken from the city dumping grounds, Champaign, August 22, 1908; from these viscera were obtained Chrysomyia macellaria (Fabricius), Sept. 7, Calliphora erythrocephala (Meigen), Sept. 11, and Sarcophaga sp. "K,"l Sept. 22. (Accession No. 41003, 1
tagmounted ; 9 head in xylol-
balsam) ; (2) One female appeared Sept. 3 from a cage containing maggots in decomposed watermelons from the same place, and from which were reared a Drosophila, August 30 to Sept. 17, and Musca dornestica, September 1. (Accession No. 39808, 1 9 tagmounted.) (3) On Sept. 10, a number of PtCromalids were collected from the cages in which muscid and other dipterous larvae were breeding and confined separately in capsules each with a single puparium of Musca dornestica. One of these Pteromalids proved to be a female of P. dubius which was observed to oviposit into the host puparium on Sept. 10. The resulting progeny proved to be a single female which was found on the fifth of the following October. (Accession No. 40177, 19 tagmounted, ?head in xylol-balsam). (4) Five males and nine females appeared October 24 or previously from a cage containing a quantity of puparia of Musca dornestica reared from the maggots collected in horse manure, Sept. 20, in a manure box in Urbana, and then left until Sept. 30 exposed in the insectary where they were evidently parasitized. On the latter date, each puparium was isolated in a capsule, and from these capsules were taken the nine females and five males; other pteromalids, Muscidi- furax and Spalangia, were very abundant. (Accession No. 40253, 4^'s, 99's tagmounted; CJ' head in xylol-balsam. Remaining d, 1 New species ; designated thus for convenience. * Homotype in IT. S. National Museum collection.



================================================================================

19101 Girault and Sanders - Chalcidoid Parasites 117 homotype in U. S. N. M.)
(5) One male appeared on October 2 in
company with a number of Muscidifurax from a large lot of puparia of Musca domestica reared from maggots in horse manure and ex- posed to parasites for three days, Sept. 8-11. On Sept. 17, the host puparia were isolated in gelatine capsules and from one of these puparia the male emerged. The puparium contained the host pupa in fragments and the single, large meconium of the parasite. (Ac- cession No. 40171, 1^ tagmounted). (6) Nine days later, October 11, from each of these isolated puparia of the same lot (Musca domestica) there emerged two males and one female. Both Spa- langia and Muscidifurax were very common in this experiment. (Accession No. 40206, 2d's, I? on tags). The characteristics of this species are the blackish aeneous color, the generally uniformly fuscous legs, the concolorous coxae, the gen- erally fuscous scape, pedicel, and basal ring-joints, the remainder of the antennae being neutral in color or nearly concolorous with the body, the polished abdomen and uniform sculpture of the thorax, the position and shape of the ocelli and the hyaline wings. Among the thousands of Chalcidoid, mostly pteromalid, parasites reared from muscid and other Dipterous larvae during the course of breeding experiments with the house fly during the latter part of the season of 1908 this species occurred very rarely as recorded in the foregoing.
Type: - Type No. 12260, United States National Museum, Washington, D. C., 1 9, tagmounted (C. F. Baker). Homotypes:- Id, 19 in the same collection, Urbana, Illinois, both tagmounted. Nothing is known concerning the biology of this genus. The
adults emerge (three cases) from the host puparium through a single circular hole with jagged edges but so far we know of no characteristic distinguishing these emergence holes from those of Spalengia or Muscidifurax. The meconium is a single dark com- pact mass circular in outline, but is not very characteristic and beggars description.




================================================================================