Conostigmus erythrothorax ( Ashmead, 1893 )

Trietsch, Carolyn, Mikó, István, Ezray, Briana & Deans, Andrew R., 2020, A Taxonomic Revision of Nearctic Conostigmus (Hymenoptera: Ceraphronoidea: Megaspilidae), Zootaxa 4792 (1), pp. 1-155 : 42-48

Conostigmus erythrothorax ( Ashmead, 1893)

Figs. 24 , 25 , 26

Species Comments and History. Ashmead (1893) described this species from several male and female specimens collected in Jacksonville, FL, noting the distinctive coloration of both sexes and remarking that it is an “easily recognized species” (pg. 120). Most descriptions and redescriptions focus on its coloration and wings (or lack thereof) ( Brues, 1916; Dodd, 1914; Kieffer, 1914), though Masner (1964) points out that while Ashmead (1893) described the species as apterous, there are vestigial wing stumps present. Brues (1916) also reports specimens being collected from the nest of “ Lasius umbratus mixtus aphidicola ” (pg. 559) in “Colebrook” (possibly in New Hampshire) of August of 1900, making this another Conostigmus species associated with ants.

The species has a unique taxonomic history. Ashmead (1893) designated this species as the type species of the genus Eumegaspilus Ashmead, 1888 and the sole species in the genus, moving canadensis and ottawensis to the genus Megaspilus . Dodd (1914) transferred erythrothorax to another new genus, Conostigmoides , and declared it as the type species for the genus. Because Ashmead transferred the only two species in the genus, canadensis and ottawensis , to Conostigmus before describing erythrothorax, Dodd (1914) reasoned that the genus Eumegaspilus was effectively synonymized with Conostigmus before erythrothorax was included in it. Dodd (1914) erected the new genus Conostigmoides to resolve this taxonomic issue.

Masner (1964) revisited the genera Eumegaspilus Ashmead and Conostigmoides Dodd. Finding that there were no differences between either genera and Conostigmus , he synonymized Conostigmoides , moving erythrothorax to the genus Conostigmus ( Masner, 1964) . Eumegaspilus later became considered a subgenus of Conostigmus ( Dessart and Cancemi, 1987) . Although Ashmead (1893) had designated C. erythrothorax as the type species for Eumegaspilus, Muesebeck and Walkley (1951) emended this because erythrothorax was described in a publication after Eumegaspilus . Muesebeck and Walkley (1951) designated C. canadensis as the type of Eumegaspilus . This decision stands with others; Dessart and Cancemi (1987) consider C. canadensis to be the type species of the Eumegaspilus subgenus of Conostigmus .

Variability. The preoccipital furrow is usually absent, but it can appear as a faint impression (USN- MENT 01212999, PSUC_FEM 34079). There is also color variation, especially with the age of the specimens. Fresher specimens tend to have a dark brown head, darker than the mesosoma (UCRC_ENT 00103618, UCRC_ ENT 00103621), whereas in older specimens, the head tends to be light brown and can even appear of similar color to the mesosoma (MCZ-ENT711742, USNMENT 01212999). This is likely a result of the specimen coloration fading over time (see Fig. 25 ).

Differences Between Males and Females. The median process on the intertorular carina is absent in females, but present and blunt in males. Other than this, as well as genitalia differences and sexual dimorphism in the antennae, there are no obvious differences between males and females.

Diagnosis. This species can be identified from the following combination of characters: postocellar carina absent; rugose sculpturing absent on head; pronotum not enlarged (pronotum shorter than the mesoscutum along the midline); median mesoscutal sulcus present and complete (median mesoscutal sulcus posterior end adjacent to the transscutal articulation); and sternaulus absent. This species also has unique coloration, with the cranium being light brown to black in color and darker than the mesosoma, which is yellow to light brown. Females can be matched to males by the characters above, as well as by their unique coloration.

This species can have similar coloration to C. nigrorufus , and also lacks a sternaulus, but the two species can be easily distinguished by the wings, which are always macropterous in C. nigrorufus and brachypterous in C. erythrothorax . Other differences include the rugose sculpturing on the head (present in C. nigrorufus ) and the male genitalia (gonocondyle blunt in C. nigrorufus and acute in C. erythrothorax ; dorsomedian conjunctiva in dorsal view extending more than or equal to 2/3 of the length of the gonostyle–volsella complex in C. erythrothorax , extending between 1/3 to 1/2 the length in C. nigrorufus ).

Another similar species is C. michaeli . These species share an incomplete occipital carina and lack the sternaulus, postocellar carina, preoccipital lunula and facial pit. The male genitalia are also similar, with the medioventral conjunctiva of the gonostyle–volsella complex present (parossiculi independent), proximal end of dorsomedian conjunctiva of the gonostyle–volsella complex shape acute, one apical parossicular seta, gonocondyle acute, and the proximodorsal notch of cupula present, U-shaped and wider than long. However, these two species differ in that C. erythrothorax has reduced wings, whereas all known specimens of C. michaeli are macropterous. There are also differences in the male ocellar triangle ratios, with OOL:POL equal to 1 in C. erythrothorax males but less than 0.8 in C. michaeli males, and OOL:LOL over 1.6 in C. erythrothorax males but equal to or less than 1.3 in C. michaeli males.

Other similar species include C. dimidiatus and C. muesebecki , which both have reduced or absent wings and similar coloration. However, both species differ in that the median mesoscutal sulcus is absent or incomplete (when present, the median mesoscutal sulcus posterior end is not adjacent to the transscutal articulation), whereas C. erythrothorax has the median mesoscutal sulcus present and complete. In addition, C. muesebecki has an enlarged pronotum (pronotum longer than the mesoscutum along the midline), whereas C. erythrothorax does not.

Description. Body length: 1.1–1.8 mm. Color hue pattern in male: cranium yellow to brown; mesosoma yellow to light brown; scape, pedicel and legs except hind coxae ochre; hind coxae white; petiole yellow; metasoma yellow to brown. Color intensity pattern in male: cranium darker than mesosoma, flagellomeres darker than legs; flagellomeres darker than scape and pedicel; petiole neck lighter than rest of metasoma; anterior half of mesosoma lighter than posterior half of mesosoma. Color hue pattern female: cranium light brown to black; scape, pedicel and flagellomeres ochre to brown; mesosoma yellow to light brown; legs light yellow to white; petiole yellow; metasoma light brown to dark brown. Color intensity pattern female: legs lighter than the flagellomeres, scape and pedicel; flagellomeres darker than scape and pedicel; cranium darker than mesosoma; petiole neck lighter than rest of metasoma; distal portion of pedicel lighter than rest of pedicel; basal portion of scape lighter than rest of scape; anterior half of mesosoma lighter than posterior half of mesosoma. Color intensity dorsal and ventral to the site of the sternaulus: concolorous. Color intensity pattern of syntergite: petiole neck and anterior region of syntergite lighter in coloration than the posterior region of the syntergite. Foveolate sculpture on body count: absent. Rugose sculpturing count: absent. Rugose region on upper face count: absent.

Antennae: Male scape length vs. pedicel length: 4.0. Male scape length vs. F1 length: 1.43. Male F1 length vs. pedicel length: 2.8. Male F1 length vs. male F2 length: 1.17. Longest male flagellomere: F1. Female scape length vs. pedicel length: 3.0–3.9. Female scape length vs. F1 length: 3.2–3.5. Female F1 length vs. F2 length: 1.1–1.3. Female F1 length vs. pedicel length: 0.8–1.2. Longest female flagellomere: F9. Length of setae on male flagellomere vs. male flagellomere width: setae shorter than width of flagellomeres. Sensillar patch of the male flagellomere pattern: F6–F9.

Head: Head width, dorsal view: at least 1.3× wider than mesosoma. Head height (HH, lateral view) vs. eye height (EHf, anterior view): HH:EHf=1.2–1.5. Head height (HH) vs. head length (HL): HH:HL=1.1–1.4. Head width (HW) vs. interorbital space (IOS): HW:IOS=1.8–2.6. Head width (HW) vs. head height (HH): HW:HH=1.1– 1.4. Cephalic size (csb): Mean: 250–400 μm. Maximum eye diameter vs. minimum eye diameter: 1.3–1.7. POL: OOL: POL equal to or shorter than OOL and ocellar triangle with short base. Male ocular ocellar line (OOL) vs. lateral ocellar line (LOL): OOL:LOL=1.67 (PSUC_FEM 34079). Male ocular ocellar line (OOL) vs. posterior ocellar line (POL): OOL:POL=1.0. Male ocular ocellar line (OOL): posterior ocellar line (POL): lateral ocellar line (LOL): 1.67:1.0:1.0. Female ocular ocellar line (OOL) vs. lateral ocellar line (LOL): OOL 1.2–1.4× as long as LOL. Female ocular ocellar line (OOL): posterior ocellar line (POL): lateral ocellar line (LOL): 1.2–1.4:1.2–1.7:1.0. Head shape (anterior view): circular or triangular. Preoccipital lunula count: absent. Preoccipital carina count: absent. Occipital carina structure: occipital carina not complete. Occipital carina sculpture: crenulate. Preoccipital furrow count: absent; present. Preoccipital furrow anterior end: preoccipital furrow ends posterior to ocellar triangle. Preoccipital furrow sculpture: appearing as a faint impression, smooth. Postocellar carina count: absent. Dorsal margin of occipital carina vs. dorsal margin of lateral ocellus in lateral view: occipital carina dorsal to lateral ocellus in lateral view. Transverse scutes on upper face count: absent. Transverse frontal carina count: absent. Randomly sized areolae around setal pits on upper face count: absent. Setal pit on vertex size: smaller than diameter of scutes. Ventromedian setiferous patch and ventrolateral setiferous patch count: absent. White, thick setae on upper face count: absent. Antennal scrobe count: absent. Facial structure count: no external corresponding structure present. Facial pit count: absent. Facial sulcus count: absent. Median facial keel count: absent. Supraclypeal depression count: present. Supraclypeal depression structure: present medially, inverted U-shaped. Intertorular area count: present. Intertorular carina count: present. Median process on intertorular carina count: present in males but not in females. Median process on intertorular carina shape: blunt on males, median process absent in females. Median process of intertorular carina structure: process does not extend across intertorular area to dorsal margin of clypeus. Median region of intertorular area shape: convex. Ventral margin of antennal rim vs. dorsal margin of clypeus: not adjacent, though very close together. Torulo–clypeal carina count: present. Subtorular carina count: absent. Mandibular tooth count: 2. Mandibular lancea count: absent.

Mesosoma: Weber length: WL=300, 310 μm.Anterior mesoscutal width (AscW) vs. posterior mesoscutal width (PscW): AscW/PscW=0.8–1.0. Mesoscutal length (MscL) vs. anterior mesoscutal width (AscW): MscL/AscW=1.2– 1.6. Mesoscutal length (MscL) vs. mesoscutellar length (MscIL): MscL:MscIL= 1.0–1.5. Wing count: absent. Fore wing size: wings reduced or brachypterous with apex never extending past scutellum. Pronotum median length: less than longest median anatomical line of the mesoscutum. Notaulus count: present. Crenulae of notaulus width: width of the crenulae does not increase more than 2× anteriorly. Notaulus posterior end location: adjacent to transscutal articulation. Posterior region of notaulus orientation: posterior end of notaulus curves and is adjacent to median mesoscutal sulcus. Median mesoscutal sulcus count: present. Median mesoscutal sulcus posterior end: adjacent to transscutal articulation. Scutoscutellar sulcus vs. transscutal articulation location: adjacent. Axillular carinae count: absent. Speculum ventral limit: not extending ventrally of pleural pit line. Metapleural sulcus shape: straight. Mesometapleural sulcus count: present. Ventrolateral invagination of the pronotum count: present. Sternaulus count: absent. Epicnemial carina count: complete. Epicnemium posterior margin shape: anterior discrimenal pit present; epicnemial carina curved. Transverse striations on the ventral metapleural area count: absent. Scutes on posterior region of mesoscutum and dorsal region of mesoscutellum convexity: flat. Ventral projection of the metapleural carina count: absent. Lateral propodeal carina count: present. Lateral propodeal carina shape: inverted “U” (left and right lateral propodeal carina are adjacent to the antecostal sulcus of the first abdominal tergum submedially). Mesopostscutellum count: absent (scutellum flat). Anteromedian projection of the metanoto–propodeo–metapecto–meso-pectal complex count: absent. Posterior margin of nucha in dorsal view shape: concave.

Metasoma: Transverse carina on petiole shape: straight. Paired blue iridescent ovoid patches on the syntergite count: absent. Shortest width of petiole neck vs. syntergal translucent patch maximum width: 1.6–2.6. Shortest width of petiole neck vs. synsternal translucent patch maximum width: 1.6, 3.25. Syntergal translucent patch maximum width vs. minimum width: 1.2–1.3. Synsternal translucent patch maximum width vs. minimum width: 1.5, 2.0. Syntergal translucent patch maximum width orientation: anterolaterally. Synsternal translucent patch maximum width orientation: anterolaterally. Synsternal setiferous patch shape: linear, with a patch of setae lateral or posterior to the synsternal translucent patch. Synsternal setiferous patch structure: comprised of a single row of setae. Synsternal setiferous patch anterior end: synsternal setiferous patch begins lateral to the synsternal translucent patch anterior margin. Synsternal setiferous patch posterior end: synsternal setiferous patch ends lateral to the synsternal translucent patch posterior margin. Synsternal setiferous patch length vs. synsternal translucent patch maximum width: synsternal setiferous patch as long as the maximum width of the synsternal translucent patch. S1 length vs. shortest width: S1 wider than long.

Male Genitalia: Distal margin of male S9 shape: convex. Proximolateral corner of male S9 shape: acute. Male S9 distal setal line/setal patch count: distal setae composing transverse setiferous line or lines. Male S9 distal setal line / setal patch structure: single or double transverse row of distal setae. Distomedian hairless area interrupting transverse row of setae or patch on male S9 count: absent with distal setiferous patch/line continuous medially. Submedial projections on proximal margin of S9 count: absent. Cupula length vs. gonostyle–volsella complex length: cupula less than 1/2 the length of gonostyle–volsella complex in lateral view. Proximodorsal notch of cupula count: present. Proximodorsal notch of cupula shape: arched (inverted U-shape). Proximodorsal notch of cupula width vs length: wider than long. Proximolateral projection of the cupula shape: blunt. Gonocondyle count: present. Gonocondyle shape: acute. Distodorsal margin of cupula shape: straight. Distoventral submedian corner of the cupula count: absent. Dorsomedian projection of the gonostyle–volsella complex count: absent. Dorsomedian conjunctiva of the gonostyle–volsella complex count: present. Dorsomedian conjunctiva of the gonostyle–volsella complex length relative to length of gonostyle–volsella complex: dorsomedian conjunctiva extending more than or equal to 2/3 of length of gonostyle–volsella complex in dorsal view. Dorsomedial margin of gonostyle–volsella complex shape: V-shaped. Proximal end of dorsomedian conjunctiva of the gonostyle–volsella complex shape: acute or V-shaped. Parossiculus count or parossiculus and gonostipes fusion: present and parossiculi not fused with the gonostipes. Medioventral conjunctiva of the gonostyle–volsella complex count or fusion of parossiculi: medioventral conjunctiva present and parossiculi independent or fused proximally. Apical parossicular setae count: one. Distal projection of the parossiculus count: absent. Distal projection of the penisvalva count: absent. Gonossiculus spine count: 2, sometimes with an additional dorsal apodeme below the second spine. Gonossiculus spine length: one spine not more than 2× as long as the other(s) (spines of similar lengths). Harpe length: harpe shorter than gonostipes in lateral view. Harpe shape: simple and not bilobed. Harpe orientation: medial. Lateral margin of harpe shape: widest point of harpe is at its articulation site with gonostyle–volsella complex. Distal margin of harpe in lateral view: acute or pointed. Lateral setae of harpe count: present. Lateral setae of harpe orientation: oriented distally. Lateral setae on harpe density: setae sparse. Dense patch of setae on the distoventral edge of the harpe count: absent. Distal setae on harpe length: setae of equal length across distal end of harpe. Distodorsal setae of sensillar ring of harpe length vs. harpe width in lateral view: setae as long as or shorter than harpe width. Distodorsal setae of sensillar ring of harpe orientation: distomedially. Sensillar ring area of harpe orientation: distomedially. Sensillar ring shape: circular. Distoventral margin of harpe in lateral view: convex.

Distribution. Nearctic.

Material Examined. Lectotype female: USA: USNMENT01339752 ( USNM) . Paralectotypes (1 male): USA: Florida : 1 male. USNMENT 01212999 ( USNM) .

Non-type material (6 females, 4 males): USA: California: 5 females, 1 male. UCRC _ ENT 00103616 , 00103618 , 00103619 , 00103621 , 00103622 , 00457106 ( UCRC) . USA: Connecticut: 1 female. MCZ-ENT 711742 ( MCZC) . USA: North Carolina: 2 males. PSUC _ FEM 1141 , 66352 ( EDNC) . USA: Tennessee: 1 male. PSUC _FEM 34079 ( TAMU) .

Figures

FIGURE 24. Conostigmus erythrothorax (Ashmead, 1893) type specimens in lateral view. A. Female lectotype (USN- MENT01339752). B. Male paralectotype (USNMENT01212999).

FIGURE 25. Conostigmus erythrothorax (Ashmead, 1893) females in dorsal view.A. Female lectotype (USNMENT01339752). B.A female collected in 2004 (UCRC_ENT 00103621). The differences in coloration between these two specimens is likely due to age. Abbreviation: median mesoscutal sulcus (mms).

FIGURE 26. Conostigmus erythrothorax (Ashmead, 1893) male genitalia. A. Ventral view (PSUC_FEM 1141). B. Lateral view (PSUC_FEM 34079). C. Dorsal view (PSUC_FEM 34079).