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Entomacis ambigua (Brues, 1903)Hemilexodes ambigua Brues, 1903: 126. Original description.Entomacis ambigua: Kieffer, 1912: 19. Generic transfer. Entomacis ambigua: Brues, 1916: 563. Redescription (essentially repeats Brues 1903). Entomacis ambigua: Kieffer, 1916: 41, 44. Redescription (apparently based on Brues 1903), keyed. Entomacis ambigua: Muesebeck and Walkley, 1951: 673. Cataloged. Entomacis ambigua: Masner, 1965: 298. Lectotype designation. Entomacis ambigua: Muesebeck, 1979: 1140. Cataloged. Diagnosis.Anteromedian and parapsidal lines indicated as short rows of bumps; forewing marginal vein never reaching anterior margin of wing; malar sulcus present; occipital carina with longitudinal carinae throughout; pronotal shoulder sharply pointed, bearing a tuberculate verricule; notaulus deeply impressed along full length of mesoscutum; median propodeal keel well developed, lower blade well developed, sharply carinate; axillae, posterior mesopleuron and usually anterior scutellar pit irregularly carinate or rugulous.Description - female.Length: 1.9-2.5mm, m=2.2 (n=10). Head (Figs. 1-3). Length: 0.34-0.40mm, m=0.37; width: 0.40-0.48mm, m=0.44 (n=10); labrum distally bearing 5-6 chalazae; clypeus semicircular, in lateral view bulging slightly, uppermost surface projecting, strongly sloping, three setae present along lateral margin; supraclypeal face in lateral view slightly projecting throughout, except for medial asetose area evenly covered with many semidecumbent setae that are generally shorter than those found elsewhere on head; malar sulcus impressed along full length of malar space (Fig. 3); torular space much narrower than base of antennal rim; patch basolaterally to antennal rim slightly irregularly sculptured; OOL longer than POL longer than LOL; postocellar vertex transversed with a few semierect setae; gena without semidecumbent setae as found on supraclypeal face, with longer semidecumbent setae that are frequently medially bent; occipital carina longitudinally carinate throughout. Antenna (Fig. 10, top). A4-A6 subequal; A7 and A8 sequentially larger; A9-A12 subequal; A13 sharply conical; MGS brush densely covering distinctly flattened ventral surfaces of A9-A13; flagellomeres slightly compressed, in dorsal view broadening from base to A10, A11-13 narrowing; antennomere connection of apical segments distinctly asymmetrical; upper sensillar line present. Mesosoma (Figs. 5-8). Length: 0.62-0.79mm, m=0.71; width: 0.41-0.53mm, m=0.46; height: 0.40-0.54mm, m=0.48 (n=10); pronotal shoulder extremely well developed, in dorsal view anterior and lateral margins forming square corner, in lateral view shoulder projecting to smooth point; anterior pronotal verricle very well developed, located on anteromedial surface of pronotal shoulder (Fig. 7); pronotum immediately anteroventral to spiracle smoothly depressed; lower pronotal seta immediately anterior to spiracle; posterolateral corner of mesoscutum flexed upwards forming rounded point; notaulus deeply impressed along full length of mesoscutum; humeral sulcus well impressed posteriorly, fading anteriorly; suprahumeral sulcus absent; anteromedian and parapsidal lines indicated as short rows of fine bumps; three pairs medial mesoscutal setae present; epicnemial pit well defined, broadly rounded with upper margin slightly vertically elongate; patch posterior to epicnemial pit finely longitudinally rugulose; post-epicnemial pit setae forming line traversing ventrolateral mesopleuron; mesopleuron with at least one, most often more, parallel longitudinal grooves in upper posterior corner; matte spot very well defined, circular, upper margin extending to around midpoint of lower mesopleural suture; upper mesopleural suture setate; anterior margin of mesoscutellum distinctly sunken relative to posterior margin of mesoscutum; anterior scutellar pit transverse, anterior margin abutting mesoscutum, pit filled with irregular rugulose sculpture, sculpture varying from nearly absent to indicated as three or more strong longitudinal keels; axilla completely obliquely carinate, carinae extending to anterolateral corners of scutellar disk; axillar depression surface covered with fine evenly spaced carinae, carinae obliterated to varying degrees in some individuals, few scattered setae present, particularly posteriorly; scutellar disk smooth, posterior margin scrobiculate; lateral trough finely carinate throughout; postmetanotal rim thin; outer process more or less parallel to postmetanotal rim; inner process reduced, indicated only as truncate corner of medial postmetanotal rim; dorsal propodeum more or less smooth, setate, lateral and posterior margins carinate; median propodeal keel very well developed, upper blade surface thick, lower blade surface sharply carinate; plical process absent; nuchal area covered with fine arcuate carinae. Wings (Figs. 32, 35). Forewing apex slightly truncate to broadly rounded; costa absent; marginal vein not reaching anterior margin of wing, area below submarginal, marginal and stigmal vein usually slightly infuscate; stigmal vein straight, thin (Fig. 32); venation otherwise absent, though course of distal RS and to lesser degree distal M and distal CU very slightly pigmented and impressed (spectral); hind wing with subcosta present at base, veination otherwise absent. Metasoma. Petiole with lines of straight semierect setae present laterally and ventrolaterally, ventrally asetose; gaster with six tergites and five sternites; T2 flange moderately developed; T2 notch short, not extending past T2 flange; T2 lateral groove absent; S2 lateral groove narrowly impressed basally, with outer margin sharply carinate; S2 nearly glabrous basally, setal line strongly indicated as fine line of setae, line nearly completely obliterated in some, marked only by few scattered fine setae; tergites and sternites past T2 usually not fully retracted (visible in dorsal view) in dead specimens. Color. Head almost black, slightly darker than dark brown mesosoma and metasoma; base of S2 distinctly lighter to darker yellow (rare in southernmost members); legs and basal antennomeres similarly colored, lighter brown-yellow; A9-A12 distinctly darker brown; A13, especially apex, often lighter than A9-A12 (females and males); overall color often lighter in individuals from southern parts of range and darker in northern.Male (differing from female)Antennae (Figs. 4, 10 (bottom)). A3 broadening from base to apex; A4 in dorsal view with apical 1/3 distinctly broader than all other flagellomeres; A4 RSS present from base A4 to near apex (best seen in ventral oblique view, in dorsal view RSS appears present only in basal 0.8); A5-A7 subequal, very slightly sequentially incrassate; A8-A13 each slightly pedunculate, together forming very slight club, ventral apices sometimes bluntly pointed; MGS brush present on very slightly flattened surface of A9-A13; upper sensillar line present; at least one ventral sensillar line present; apical antennomeres slightly asymmetrically connected. Metasoma. Gaster formed by six tergites and seven sternites.Figures
Biology and Distributions.Widespread, in eastern North America (red circles in map below). Collection dates: 1901-2000; Jan. 1 to Dec. 24. Elevation range: 80 to 1600m (n=6). Host: Brues (1903) states that the syntypical series was collected in a nest of Stennama fulvum var. piceum (Formicidae). He believed it to be parasitizing myrmecophilous Diptera. Muesebeck and Walkely (1951) note the ant to be Stenamma fulva aquia var. picea Emery. Muesebeck (1979) notes the ant to be Aphaenogaster rudis picea (Emery). If there is a specific relationship between fly and ant then correlation of these data with elevational distributions of Aphaenogaster species may aid in the search for hosts of E. ----- sp. nov. Entomacis ambigua appears to be a stronger flyer than most species of Entomacis , it is commonly collected in Malaise traps. Elevation data suggest that E. ambigua and E. ----- (green triangles in map below) the two species are allopatrically separated via elevation. Entomacis ambigua is known from 80 to around 1600m while E. ----- sp. nov. is known from 1554-2514m.
Material Examined66 females, 14 males.Primary Type Material:USA: Connecticut: Litchfield Co.: Lectotype ?; "Nest Stenam{?m}a / bu{?liriru} piceum / Colebrook 8.25.01,", "Type,", "M.C.Z. / Type / 31021,", "LECTOTYPE Female / Hemilexodes / ambigua Brues / By L[ubomir]. Masner, [19]'64,", "Hemilexodes / ambigua / Brues." (MCZ). Condition: Good, no parts missing, color likely slightly faded from original state.Additional Material:Additional Material: Paralectotypes: USA: Connecticut: Litchfield Co.: (CNC) 1 fem.; Other: Canada: Ontario: (CNC) 11 fem., 2 ml.; Quebec: (CNC) 4 fem.; USA: Arkansas: Johnson Co.: (CNC) 1 fem., 1 ml.; Washington Co.: (UADE) 1 fem.; Florida: Alachua Co.: (CNC) 1 fem., 2 ml.; Indian River Co.: (CNC) 1 fem.; Orange Co.: (UCFC) 9 fem., 2 ml.; Sarasota Co.: (UCFC) 1 ml., 1 fem.; Seminole Co.: (UCFC) 1 ml.; Illinois: McHenry Co.: (INHS) 1 ml.; Kentucky: Whitley Co.: (CNC) 1 fem.; Maryland: (CNC) 1 fem.; (MJY) 1 fem.; Calvert Co.: (CNC) 1 fem.; Michigan: Berrien Co.: (CNC) 1 fem.; Washtenaw Co.: (CNC) 2 fem.; Missouri: Wayne Co.: (CNC) 1 fem.; North Carolina: Jackson Co.: (CNC) 1 ml.; Macon Co.: (CNC) 1 fem.; Oklahoma: Latimer Co.: (CNC) 1 fem., 1 ml.; South Carolina: Charleston Co.: (CNC) 1 fem.; Tennessee: Henderson Co.: (CNC) 1 fem.; Virginia: (CNC) 1 ml.; Essex Co.: (CNC) 17 fem., 1 ml.; Fairfax Co.: (CNC) 1 fem.; Wisconsin: Fond du Lac Co.: (IRCW) 1 fem.; Grant Co.: (IRCW) 1 fem.; Jackson Co.: (IRCW) 3 fem.Remarks.This species is one of the more morphologically distinct species of Entomacis . Its species-group name and original description in a new genus (Hemilexodes) reflect the uncertainty of Brues (1916) as to its relative place within the Diapriinae and its relationship to other species of Entomacis . Based on the phylogenetic analysis it is clear that ambigua belongs in Entomacis . Entomacis ambigua has an interesting mix of apomorphic and plesiomorphic characters. While the malar sulcus and well developed clava suggest a relationship with basal Entomacis species, the very well-defined matte spot, marginal vein that does not meet the anterior margin of the forewing, and well-developed pronotal shoulder suggest a derived position. Within E. ambigua, due to the variation in color, sculpture, and size exhibited by both males and females, smaller lighter males and larger darker females (or vice versa) appear morphologically distinct. Although sculpture over all parts of the body (e.g. longitudinal carinae of occipital carina, rugose sculpture of anterior scutellar pit, longitudinal grooves of mesopleuron and fine carinae of axillar depression) may be obliterated to varying degrees, there is always at least some indication of sculpture in each area noted in the description. Smaller individuals may have the anterior scutellar pit more rounded, and not transverse. The matte spot may be smaller in males. In particular a male specimen from Arizona had a distinctly smaller spot. Color varies strongly with latitude, with southern members possessing distinctly lighter (in extreme cases dark yellow) legs, propodeum and base of S2. Male antennae (Fig. 10, bottom) of E. ambigua are unusual among species of Entomacis in that they exhibit a reduced clava similar to that found in females. Entomacis ambigua is sister to E. ----- sp. nov. The latter can be seen as a transitionary form between the majority of members in clade D and E. ambigua (phylogeny). Entomacis ------- sp. nov. is smaller (the largest measured specimen of E. ----- was smaller than the smallest measured specimen of E. ambigua) and less robustly sculptured throughout. Entomacis ----- is much less robust than E. ambigua. Carinae present on the body of E. ambigua are generally reduced or absent in E. -----. The anteromedian and parapsidal lines that consist of rows of bumps in E. ambigua are clearly absent in E. -----. However, these areas are occasionally slightly irregularly formed or elevated (particularly around the ancestral location of the anteromedian lines) but are never indicated as in E. ambigua. |
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Red circles mark ambigua distribution, Green triangles mark its undescribed sister speciesThis material is based upon work supported
by the National Science Foundation under Grant No. 9712543. Any opinions,
findings and conclusions or recommendations expressed in this material are
those of the author(s) and do not necessarily reflect the views of the National
Science Foundation.