Chlorocytus analis (Ashmead, 1895),
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|Chlorocytus analis (Ashmead, 1895)|
Chlorocytus analis (Ashmead, 1895) n. comb.
Ashmead (in Davidson 1895) described Aetroxys analis as a parasitoid of the bee species now known as Hylaeus ellipticus (Kirby) ( Colletidae ) in twigs of “elder and mustard” near Los Angeles, California. The Antelope Valley was mentioned specifically as a rearing locality in the publication. However, R. Snelling (personal communication) assured me that H. ellipticus should not have occurred in that region. We have been unable to locate Davidson’s material, but it seems best to consider the host material of this species to be an unidentified species of Hylaeus Fabricius. The main diagnostic characters of the species as stated by Ashmead were the elongate gaster and whitish apical gastral tergites in females.
Aetroxys analis was later transferred without comment by Peck (1951) to Habrocytus Thomson , which is now a subgenus of Pteromalus Swederus. Graham (1956) described the genus Chlorocytus to contain many Palearctic species previously placed in a few different genera, mostly from Pteromalus and Habrocytus , but not all Nearctic species of those genera were reviewed to determine which species belonged in Chlorocytus . The senior author (RAB) examined the current holdings of the type series of Aetroxys analis from USNM, one female and three males, and determined that the species actually belongs to the genus Chlorocytus based on the following features: prepectus alveolate with its dorsal margin distinctly longer than tegula; pronotal collum relatively long, visible from dorsal view for a distance about twice the medial pronotal collar length (Figs. 1, 2; measured from dorsal view with pronotal collar presented flat to observer); clypeal margin broadly and shallowly emarginate medially; propodeal nucha present as a very short and unsculpted strip (Fig. 1); and petiole not elongate (Fig. 3). We are not aware of the location of the other seven males mentioned in the original description, and they are assumed lost. While none of the specimens remaining from the type series have an antennal flagellum, Ashmead’s description implies that some of the males did and that the first two flagellomeres are distinctly different in size from the 3 rd (presumably anelli). The propodeum is not of the typical kind for Chlorocytus in that it is relatively short (> 3 x broader than medial length) and with a straight and distinct median carina (Fig. 1), but these conditions occur to varying degrees in some other species of Chlorocytus and we do not consider them to have generic value. The only distinct difference from other Chlorocytus is the whitish 6 th and 7 th gastral tergites in females (Fig. 3), which we do not consider to alone justify separation from Chlorocytus .
Lonchetron Graham and Eulonchetron Graham are two small genera of Pteromalini similar to Chlorocytus and known for having a long gaster in females, but this species does not seem to belong to either of those genera. Species of Lonchetron differ in having a distinct genal concavity, while females of Eulonchetron have a greatly elongate apical gastral tergite that is at least 1 / 3 the total gastral length. The possibility that the species may belong to Mesopolobus Westwood was also considered and rejected for three main reasons: many body parts (including the propodeum, head, and pronotum) are considerably more like those of certain Chlorocytus than those of any Mesopolobus , it could not be placed in any species group of Mesopolobus either morphologically or biologically, and the males do not possess any of the special sexually dimorphic characters usually found in species of Mesopolobus . Likewise, the form of the propodeum, among other characters, eliminates certain other genera with southern Californian species possessing a similar gaster in females, such as Homoporus Thomson , Arthrolytus Thomson , and Holcaeus Thomson.
As there are many described and undescribed species of Chlorocytus and the genus is in need of review, a succinct diagnosis cannot be provided. Chlorocytus analis females are different from all other species of the genus in that the gastral apex (Fig. 3) is whitish and more nearly membranous than the remainder of the gaster (which is more normally sclerotized), but we have no guarantee that these characters are consistently present in the species as they may have been an artifact of rearing. Davidson mentions that all the specimens of the original series were attached to each other by the gastral tips upon pupation and he could not have observed that without physically opening the brood chambers and thereby exposing the specimens to unusual conditions. Nevertheless, these gastral characters are not present in males. The propodeum (Figs. 1, 2), being shorter than normal for the genus and having a strong and complete median carina and distinctly raised alveolate sculpture on the median panels, can be used to correctly identify both sexes. In Graham’s (1969) key to species of Chlorocytus , it would run essentially to couplet 20, except that the propodeum is nearly half the scutellar length and the nucha projects distinctly beyond the supracoxal flange. If keyed alternatively, it would run to couplet 19, where it would differ from both Chlorocytus spicatus (Walker) and Chlorocytus pilosus Graham by the much longer gaster in females.
Condition of types. 1 Ψ syntype (Figs. 1–3) “Los Angeles, Cal” “ Type ” “ Type No. 41249 U.S. N.M.”: the gaster is detached and glued to the same card as the rest of the body, the left forewing remains only weakly attached to the body, and the left hind leg is missing past the metacoxa; both antennae lack a pedicel and flagellum. There is a broken microscope slide, missing a section, associated with these specimens at USNM. The remainder of the slide is still viewable and contains various leg sections. However, these leg sections are variable in size and probably consist of parts of the legs from some males in addition to possibly containing parts of the hind leg of the female. The below redescription refers to the cardmounted female alone, without reference to the slide. The three male specimens are all card mounted and all lack the antennal flagellum. 1 ɗ Syntype “Los Angeles Cal” “ Type ” “Allotype No. 41249 U.S. N.M.”: (I have seen no published lectotype designation, and consider all of these specimens to be syntypes) lacking its head. 2 ɗ Syntypes “Los Angeles Cal” “ Type ” “ Paratype No. 41249 U.S. N.M.”: one is complete except that it lacks both antennal flagella; the other “ paratype ” consists only of a separately mounted head and mesosoma
Description. Syntype female. Body length 4.52 mm (24.4 in relative units used below).
Color: Head and mesosoma mostly dark bluishgreen, with dark setae; eye reddishgray; ocelli light brown. Gaster mostly dark brown with metallic luster, with slightly paler areas across the separation of each pair of tergites, but apical pair of tergites whitish with white setae; ovipositor sheaths dark brown. Exposed portion of mandibles reddish; maxillary and labial palps light brown. Scape light brown basally, becoming gradually darker in apical quarter. Venation light brown. Legs almost entirely light brown, except pro and mesotibiae slightly fuscate along most of their length, apical tarsomeres darker brown, and coxae same color as mesopleuron.
Sculpture: Head and mesosoma mostly alveolate, aside from the smooth upper mesepimeron and striate lateral panels of preaxilla and axilla. Gena behind malar sulcus distinctly more finely alveolate than area anteriad of the sulcus. Dorsellum transversely alveolate. Metapleuron mostly alveolate, with smaller and shallower meshes than those of lower mesepimeron and upper mesepisternum, posteroventral corner with a distinct pit. Propodeal median panels regularly alveolate, with areas behind and laterad of spiracles more shallowly alveolate in curved rows of meshes that give it almost a striate appearance; nucha finely transversely striate.
Head width 5.3, height 4.2, length 2.4; bottom of toruli very slightly above lower eye margin; VTD 2.4; MTD 1.5; clypeus shallowly emarginate; EH 2.2; MS 1.7; MW 2.55; POL 1.05; OOL 1.1; EL 1.5; TL 0.6; genal concavity not formed. Scape broken off near apex, remaining section long and narrow, reaching bottom of median ocellus, which is consistent with that of the males in which the scape is whole. Mandibular denticles not seen by me.
Mesosoma (Figs. 1–2). Medial pronotal collar length 0.3, pronotal collar lateral length 0.6, total medial pronotal length (from dorsal view, including collum) 0.9, width 3.1; mesoscutum length:width 2.4: 3.3; scutellum 2.3: 2.3 (width across frenal groove); dorsellum present as a small band 0.1 x scutellar length; propodeum length 0.9 (medially). Pronotal collar sharply margined anteriorly but not at all carinate, separated from mesoscutum laterally by a distinct notch, posterior smooth strip of uniform length, lateral scrobe deep and smoothly curved, collum moderately long and sloping; notauli incomplete; frenal groove relatively distinct; dorsal margin of prepectus about 1.3 x tegula length. Propodeum with complete median carina and indistinct plicae, ISD 2.2; anterior plical pits deep and nearly circular, not sculpted; posterior plical pits indistinct; spiracles long but not emarginate; postspiracular furrow broad and shallow, uninterrupted; callar setae present mesally to spiracle level; nucha extremely short and striplike, concave apically, basal crossfurrow crossed by small carinae in places, basal crosscarina present, apical width 1.1, projecting maximally 0.4 from supracoxal flange. PRF 3.4: 0.75; PRT 3.3: 0.4; MSF 3.4: 0.7; MST 4.7: 0.45; mesotibial spur not visible; basal mesotarsomere 1.1; MTF 5.2: 0.6; MTT 5.3: 0.5; metatibial spur 0.5; basal metatarsomere 1.9. FW 11.6: 4.6; CC 4.8; MV 2.1; PMV 2.5; stigma a blunt slight expansion of its stalk, shortest distance from uncal apex to postmarginal vein 0.6, from stigmal apex to postmarginal vein 1; uncus about 1 / 3 greatest stigmal width; costal cell with one complete row of ventral setae and additional ventral setae in apical quarter; speculum reaching parastigma anteriorly, open posteriorly; basal cell and fold bare; cubital and subcubital setal tracks ending at speculum. HW 8.45: 2.1, with a sclerotized but unpigmented basal vein.
Petiole medial length 0.6, apical width 1. Gaster (Fig. 3) dorsally collapsed and flattened, broadest at apex of 2 nd tergite, length x width 15.8: 3.7, dorsally without rigid form and tending to collapse beyond the first tergite. First gastral tergite 1.9: 3.4. Seventh (apical) tergite medial length 2.5, basal width 0.8, with separation from sixth tergite very difficult to discern; hypopygium not visible; ovipositor not exceeding gastral apex.
Male syntypes. Body length in the one relatively intact male 2.4 mm (13 in relative units); this is likely a small specimen, as it is the smallest in all other measurements. Differing from female in the following characters: basal metatarsomere much shorter: 0.8–0.9 (metatibial spur 0.3); petiole medial length 0.3, posterior width 0.7–0.8, with a fine but relatively long and sharp lateral denticle on each side near midlength, these denticles slightly over half as long as medial length of petiole; gaster length 3.5–3.6 (mesosomal length 2.8 – 3.0 in the same specimens), without a pale subbasal blotch, 6 th and 7 th tergites same color as remainder of gaster.
Variation: No significant variation noticed.
Meximalus Bou č ek
We collected a single female of this genus at the Southwestern Riverside County Multi Species Reserve (formerly the Shipley Reserve) northeast of Lake Skinner in Riverside Co., CA. Males were found upon searching malaise trap samples from nearby parts of the same reserve. The senior author (RAB) compared the female with the holotype and only known specimen of Meximalus heratyi Bouček ( USNM) and found them to differ in three important ratios given in the diagnosis below. They also differ in overall relative size of the vertex and occiput, a difference best appreciated comparing Figs. 4–5. These are the first records of the genus aside from the type locality of M. heratyi in Guerrero, Mexico, and first discovery of males of the genus.
Salient, possibly generic, characters of the male are provided here, in addition to generic characters for both sexes that have been discovered or clarified through the new material.
Males. Flagellomeres (Fig. 6) cylindrical and not pedicellate, transverse and shorter than pedicel, each with 1 dense row of longitudinal sensilla that are about equal in length to their respective segment, but project slightly beyond its apex. Segment surface between longitudinal sensilla glossy and with inconspicuous longitudinal setae between the longitudinal sensilla. Additional flagellar setae very tiny, in only one row arising at a distinct angle from each segment base, but rarely an occasional tiny erect seta arising from another location. Club without an apical spicule. Eyes relatively small: eye height 1.3–1.6 x malar space, 0.4–0.5 x head height, 0.5–0.6 x least interocular distance.
Scutellum not extending over propodeal base (Figs. 7, 8), but frenum and dorsellum perpendicular with remainder of scutellum; frenal division in the form of a weak dorsal crest (best seen in profile).
Petiole slightly longer than apical width, very shallowly coriaceous dorsally except at extremes; with a tiny lateral denticle on each side at midlength. Basal flange from first gastral sternite more reduced and very difficult to discern, not visible from dorsal view; gaster without a pale subbasal blotch.
Both sexes. the following information was not included by Bouček in the original generic description or needed clarification. Both mandibles are confirmed as having three wellseparated denticles (Fig. 9). Although occipital carina absent, occiput at a different slope from postocciput, the separation between the two abrupt (this more distinct in males). Pronotal collar without posterior smooth strip or row of posteriorlydirected setae (Fig. 8); pronotal scrobe open dorsally, such that pronotal collar has a broad middle notch on each side in dorsal view. Forewing basal cell with some scattered setae, basal fold setose; speculum posteriorly closed by a dorsal and ventral row of setae along subcubital fold, and with a few isolated dorsal setae in all specimens; costal cell with a complete ventral row of setae and additional dorsal and ventral setae in apical half. All specimens with only one discernable metatibial spur. Cerci peglike and exserted.
Discussion. Meximalus belongs to a vaguely defined group of Pteromalini which have a propodeal costula smoothly meeting the anterior plicae but which lack posterior plicae. This group includes Psilocera Walker and a large but currently indeterminate number of other genera, and will be more concretely definable after further analysis. Meximalus is unusual in this group in possessing only one metatibial spur. The form of the antenna suggests a possible relationship with certain other members of that group in which the flagellomeres in males have very few short or appressed flagellar setae and one row of regularlyspaced longitudinal sensilla that are about equal to their respective segment length, such as Bonitoa Bouček , which is known only from males. Males of these two genera share a number of other characters aside from antennal form, including detailed similarity in clypeal, genal, mandibular, male petiolar, and propodeal form. They differ in the form of the gastral tergites, in that the funicular segments in Bonitoa are more distinctly separated by their narrower stalks, and in the unique generic characters of Meximalus .
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