Dolichovespula stigma Lee, 1986

Tan, Jiang-Li, Zhou, Tong, Tan, Qing-Qing, van Achterberg, Cornelis & Carpenter, James M., 2017, Nest structure and all stages of the long-cheeked yellow jacket Dolichovespula stigma Lee (Hymenoptera: Vespidae), with a new synonym, Journal of Natural History 51 (13 - 14), pp. 793-806 : 794-804

Dolichovespula stigma Lee, 1986

Dolichovespula stigma Lee, 1986: 195 .

Dolichovespula sinensis Archer, 1987: 29 . Synonymized by Archer, 1994.

Dolichovespula baileyi Archer, 1987: 30 , syn. nov.

Diagnosis

This species can be easily identified by the combination of the following characters: ocular sinus black with a ventral yellow stripe extending to the clypeal margin; clypeus yellow with a central brown or black spot, sometimes the black spot is elongated without reaching the dorsal or ventral margin of the clypeus; apical lateral angles of the clypeus semicircular; gena with a continuous anterior yellow band not interrupted by black markings; oculo-malar space long; pronotum punctate without rugae; male genitalia: dorsal margin of paramere (DMP) only slightly more projecting inwards than in Dolichovespula norwegica (Fabricius) and less than in Dolichovespula saxonica (Fabricius) .

Queen

Queen ♀ q (n = 3), length of body (measured from the anterior margin of the head to the end of the second metasomal tergum) about 11.0 mm, fore wing length about 13.5 mm; width of metanotum (including tegula) about 5.1 mm. Vertex black with two yellow spots or narrow stripes posteriorly ( Figure 1 (a–c)); OMS black with yellow mark, HW/ OMS = about 6.2; clypeus convex with emarginate apico-median margin, about 1.08× as broad as high ( Figure 1 (e)); inner antennal distance longer than antenocular distance; the anterior yellow band of gena relatively wide with its posterior margin smooth; metasoma black with yellow marks as follows: dorsal surface of tergum I, tergum II except basally and a central projection half-way across segment ( Figure 1 (d)), sometimes a central spot on tergum III, lateral apical spot on sternum II, basal margin of sternum V, apical and lateral margins of sternum VI ( Figure 1 (a–c)).

Worker

Worker ♀ w (n = 10), length of body (measured in the same way as the queen) about 9.3 mm, fore wing about 11.0 mm; width of metanotum (including tegula) about 4.0 mm. Vertex black; OMS black with or without yellow mark, HW/OMS = about 6.5; clypeus convex and apico-medially slightly emarginate, about 1.08× as broad as high ( Figure 1 (g)); anterior yellow band of gena (temple) medially narrowed and with its posterior margin notched; metasomal terga I–V and sterna II–V each with a narrow yellow band; tergum VI entirely black; sternum VI has a lateral yellow spot; yellow band may fail to reach margin of terga III–V and be centrally interrupted on tergum V and sterna III–V ( Figures 1 (f) and 2(a)); tergum II may have two yellow patches connecting or not with apical band ( Figure 2 (a–c)).

Male

Male ♂ (n = 10), length of body (measured in the same way as the queen) about 10.1 mm, forewing 13.0 mm; width of metanotum (including tegula) about 4.3 mm.

Head. Head in frontal view about 1.06× as wide as high ( Figure 3 (b)); in dorsal view 2.9× as wide as long, gradually contracting behind eyes, slightly emarginated posteriorly, about 0.8× as broad as mesoscutum (including tegulae; Figure 2 (d–f)). Gena in lateral view gradually widening ventrally; upper 0.8 of anterior yellow band of gena narrowed; occipital carina incomplete, reaching near ventral 0.4 ( Figure 3 (a)); OMS long, HW/OMS = about 5.2 ( Figure 3 (b)); OOL: diameter of ocellus: POL = 13: 6: 8; POL/ APOL = 1.5, POL/PBHL = 0.8 ( Figure 2 (d–f)); clypeus convex with roughly truncate apicomedian margin, about as broad as high. Inner antennal distance 4.4× longer than antenocular distance ( Figure 3 (b)); margin behind inner mandibular tooth straight. Antenna with 13-articles, 8th to 13th articles each with a raised tyloid ( Figure 3 (c,d)); scape slightly curved, about twice as long as its apical diameter; third article about 3.1× as long as its apical diameter, shorter (about 0.8×) than fourth and fifth articles combined; terminal article about 2.8× as long as its basal width ( Figure 3 (c,d)).

Mesosoma . Mesosoma stout, about 1.15× as long as wide ( Figure 2 (d–f)), 1.20× as long as high ( Figure 3 (a)). Pronotum in dorsal view narrowly rounded anteriorly, with straight lateral sides diverging posteriorly; ventral corner gradually narrowed; pronotal carina present, but indistinct or absent dorsally, interrupted by pronotal pit; pretegular carina incomplete ( Figure 3 (a)).

Metasoma. Metasomal segment I about 3.9× as long as wide in dorsal view ( Figure 2 (d–f)); metasomal tergum VII triangular in lateral view and truncate apically in dorsal view ( Figure 2 (g,h)); sternum VII curved with a narrow transparent lamella laterally and roughly truncate apically ( Figure 2 (g,i)).

Genitalia. Parameres (pa) in dorsal view smoothly curved inwards; dorsal margin of paramere (DMP) slightly inwards projecting and with long setae; dorsal terminal process indistinct, rounded apically ( Figure 3 (e)); in ventral view paramere distinctly projecting inwards at midpoint; ventral terminal process (namely, parameral process) flattened, pointed apically, widely folded inwards without setae ( Figure 3 (f)); in lateral view ventral margin nearly straight ( Figure 3 (g)); parameral spine ends in a distinct point dorsally, extending beyond the parameral processes ( Figure 3 (f)); volsella arises from the inner wall of each paramere, bearing a cuspis (cu) and a digitus (di), with rows of dark small spines basally ( Figure 3 (i)); digitus (di) flattened and oriented dorso-ventrally, densely covered with setae, extending to about level of ventral terminal process ( Figure 3 (h)); aedeagus (ae) shaft narrow, expanding apically as a bifurcated flattened structure, smoothly curved inwards without lateral compression, extending to about the level of apical digitus ( Figure 3 (f)).

Setosity and sculpture. Body densely covered with long erect setae; long setae on clypeus, frons, gena, vertex, mesoscutum, scutellum and fore leg mainly dark brown or blackish brown, while setae on other parts are pale brown. Clypeus finely punctate with interspaces about three times diameter of punctures, but punctures closer apically and laterally; vertex, gena, ocular sinus and frons between the two antennal sockets densely punctate ( Figure 3 (b)); pronotum punctate; mesopleuron and mesoscutum moderately to densely punctate, with interspaces slightly less than to 3× longer than diameter of punctures; propodeum punctate; metasoma superficially punctate ( Figures 2 (d–f), 3(a)).

Colour. Body black to blackish brown with irregular yellow patches or bands on the following parts: clypeus except its black margin and a central black spot or stripe, mandible except for inner margin, large shield-shaped frontal marking, antenna ventrally, ventral part of ocular sinus, anterior of gena, anterior and dorsal margin of pronotum, tegula, antero-lateral spots of scutellum and metanotum; mesal, lateral and apical patches on femur, tibia except anterior brown spot, tarsus, apical band of metasomal segments I–VII (generally narrow and parallel, but variable especially on tergum II), yellow apical band can be sinuate and broad as in Figure 2 (e,f). Wing membrane hyaline with veins dark brown.

Specimens examined

One ♀ w, Suifu , Sz, China, vi .1–21[19]28, alt. 1000–1500 m, coll. DC Graham, from coll. USNM, Dolichovespula sinensis Archer, 1987 , paratype, det . ME Archer . 14♀ w + 30♂, one

nest (males and workers, without queen), Huanghualing (33.79° N, 108.86° E, alt. 1565 m), Yingpan, Zhashui , Shaanxi, 2013 .vii .14, Jiangli Tan; 1♂, Liuba, Ziyang , Shaanxi, 26 .v .1983, Jinsheng Lu; 1♀ q + 13♀ w, 1 nest (workers and one queen, without males), Xunyangba (33.55° N, 108.55° E, alt. 1481 m), Ningshan , Shaanxi, 27 .vi .2016, Jiangli Tan; 3♀ w, Xunyangba, Ningshan , Shaanxi, 1 .vii–15 .viii .2016, Mal . trap, Jiangli Tan and Qingqing Tan; 2♀ w, Huangguan, Ningshan , Shaanxi, 1 .vii–15 .viii .2016, Mal . trap, Jiangli Tan and Qingqing Tan; 1♂, Liuba, Ziyang , Shaanxi, 26 .v .1983, Jinsheng Lu; 1♀ q, Mt . Liupan, Ningxia, 8 .ix .2005 , green trap; 1♀ q, Shennongjia , Hubei, 7 .vi .2010 , Maoling Sheng .

Distribution. China (Hubei, Shaanxi, Sichuan, Ningxia).

Nesting sites and nest structure

The two nests of D. stigma were both found in the montane zone at an altitude of about 1500 m, hanging in grass just above the ground. The envelope of the nest is blue grey striped with parallel lines of pulp composed of 7–12 layers of paper ( Figure 4 (a–d)). The round entrance to the nest was situated below ( Figure 4 (d)).

One nest, on which we failed to find any queens during our collecting, is supposed to be an orphan colony, because it only produced males; it is ball-shaped with a diameter about 9 cm, consisting of three combs with about 400 cells ( Figure 4 (f)). Each comb is typically circular and surrounds the central mainstay, where a slight swelling is apparent. The comb, however, does not become flat but bends upwards rather steeply toward its edge. Diameters of the combs (measured from top down) are 6.5 cm, 5.7 cm and 2.4 cm, respectively ( Figure 4 (f)). The uppermost comb is connected to the inner top of the envelope broadly by a central buttressed sheet (thin ribbon-like pillar each a few centimetres long, constructed surrounding the mainstay) with diameter of 3.8 cm and reinforced by the periphery connecting with the inner layer of envelope completely. Two generations are visible according to the cyclic arrangement of the successive broods and cocoons. The second comb is attached to the one above by a buttressed sheet about 1.0 cm wide centrally. Only one generation was observed; most cells are capped by silken cocoons. The lowest comb has only a narrow central pedicel. It has one developing generation without cocoons. One twig penetrates the envelope and is attached to the uppermost comb margin and the central top of envelope. The distance between the top of one comb and the next comb is short, about 0.5 cm. Cells are hexagonal and mostly regularly arranged with the average diameter (between opposite sides) 4–6 mm, usually 5 mm (n = 20). Cells are variable in length and in the degree to which cocoons extended outside, 3–9 mm (n = 20) high at the periphery without cocoon and increased as the stage advanced. Cells had been capped by silken cocoons about 12–14 mm high, usually 12 mm (measured without cocoon, n = 20). Cocoon caps are white and protrude about 5 mm beyond the cell mouth.

The other nest was a developing colony with many workers and one queen, ovalshaped with short diameter about 9.9 cm, longer diameter 11.3 cm, with three combs and about 520 cells ( Figure 4 (e,g)). Diameters of combs are 7.9 cm, 7.2 cm and 5.4 cm, respectively ( Figure 4 (g)). Similar to the former nest except the uppermost comb hangs from the inner top of the envelope by a broad central buttressed sheet with a diameter of 2.0 cm. Cells with cocoon caps are 20–24 mm high. Cocoon caps of second comb are slightly larger than those of the uppermost comb, protruding about 6 mm beyond the cell mouth. Unfortunately many larvae died and decayed after the survey, before the nests were examined in the laboratory.

Egg

The egg is milky-white, elongate oval, about 2.0 mm long, maximum width 0.8 mm, a little larger at one end, slightly curved, and is generally attached by its smaller end to the inner side wall of cell basally, adhering to the wall by a gummy substance on its surface. The egg chorion is membranous; its surface soft and smooth without any sculpture ( Figure 5 (a)).

Larva

The larval body is white and soft except for the chitinized head; it consists of three thoracic and ten abdominal segments, with no constriction between thorax and abdomen. The structure of the head in the younger larvae is generally the same as that in the mature larvae ( Figure 5 (b,c)). Subtle differences of mandible shape are present in different instars ( Figure 5 (h,i)).

Mature larva. Body 1.3–1.8 cm long and 4.3–5.4 mm wide; cranial width: 2.2–2.5 mm (n = 5). Cranium nearly unpigmented, at most whitish brown; margin of parietal band, apical part of mandible, margins of maxillary and labial palpi and of galea brown; mandibular teeth dark brown. Margins of spiracles pale brown ( Figure 5 (c,f– i)).

Cranium. Widest part of cranium in frontal view above level of line joining antennae, about 1.2 times as wide as high, with lateral margins sinuate near ventral margin; integument with scattered minute setae, except part of gena (or temple, along the latero-posterior margin) with dense minute setae ( Figure 6 (e)); gena ventrally with sparse spicules; clypeus with few punctures and short setae; numerous minute spicules present in the area between clypeus and labrum. Outer 0.4–0.6 of parietal band reticulate. Ecdysial sulcus shallow, distinct in upper part, obliterated ventrally. Antenna with three minute sensilla. Labrum with punctures, several punctures bearing short setae, and with more than 10 conical papillae along two lateral margins ( Figure 6 (d)). Each side of palate with three small yellowish brown patches bearing more than 10 relatively large sensilla; dense minute spicules present in median part and ventro-lateral area; medio-ventral margin with about 14 conical papillae ( Figure 6 (c)). Mandible well chitinized in its concave apical part, with single, distinct apical tooth, which is blunt apically; two dorsal teeth shallowly serrated and very poorly defined ( Figure 5 (f)), inner surface with dense spicules ( Figure 6 (c)). Maxilla with scattered short setae; upper surface and apex with spicules; three and two apical sensilla were observed on maxillary palpus and galea, respectively ( Figure 6 (b)). Labium with sparse minute setae in area ventral to labial palpi, and two setae above each labial palp; area between labial palpi and spinneret with spicules ( Figure 6 (b)); spinneret shorter than the distance between the two labial palpi and surrounded by dense spicules; labial palp with five apical sensilla, one of which is relatively small.

Mesosoma and metasoma. The cuticle integument with scattered, short setae and minute spicules ( Figure 6 (f)). The abdomen has 10 pairs of spiracles, with the second and tenth pairs distinctly smaller than the rest ( Figure 5 (c)); atrial wall of spiracle with dense minute spicules; processes at perimeter of primary tracheal opening of spiracles variable in shape, with numerous micro-branches and many branches arising all over processes ( Figure 6 (a)).

Pupa

Body 1.5–1.9 mm long and 4.5–6.5 cm wide (n = 10); pupa exarate, creamy-white; compound eye brown; mandible tips yellowish brown. Similar to adults in appearance;

wing pads extending approximately to the posterior margin of first metasomal segment ( Figure 5 (d,e)).

Figures

Figure 1. Dolichovespula stigma Lee, 1986. (a–e) Queen (♀q): (a) Habitus (from Shaanxi), dorsal view; (b) ibid, Ningxia; (c) ibid, Hubei; (d) habitus (from Shaanxi), lateral view; (e) head, anterior view. (f, g) Worker (♀w): (f) Habitus, lateral view; (g) head, anterior view.

Figure 2. Dolichovespula stigma Lee, 1986. (a–c) Worker (♀w), dorsal view, showing variation of colour pattern; (d–f) male (♂), dorsal view, showing variation of colour pattern; (g) metasomal terminal segments of ♂, lateral view; (h) ibid, dorsal view; (i) ibid, ventral view.

Figure 3. Dolichovespula stigma Lee, 1986 (♂). (a) Habitus, lateral view; (b) head, anterior view; (c) right antenna; (d) terminal four segments of antenna; (e) genitalia, dorsal view; (f) ibid, ventral view; (g) ibid, lateral view; (h) paramere, inner view; (i) volsella with cuspis and digitus. Abbreviations: ae, aedeagus; cu, cuspis; di, digitus; pa, paramere; DMP, dorsal margin of paramere; PP, parameral process; PS, parameral spine.

Figure 4. Dolichovespula stigma Lee, 1986. (a, b) Nest from Xunyangba; (c, d) nest from Niubeiliang; (e) combs of nest; (f) three layers of the combs from nest of Niubeiliang; (g) ibid, from Xunyangba.

Figure 5. Dolichovespula stigma Lee, 1986, immature stages. (a) Egg (slightly deteriorated); (b) young larva, ventral view (slightly deteriorated); (c) mature larva, lateral view; (d, e) pupa; (f) head of mature larva, anterior view; (g) ibid, dorsal view; (h) mouth parts of mature larva; (i) mouth parts of young larva.

Figure 6. Dolichovespula stigma Lee, 1986, mature larva. (a) Spiracle; (b) part of mouth parts, showing maxillary palp, galea, labial palpi and spinneret; (c) palate and part of mandible; (d) left half of labrum, frontal view, showing minute setae and conical papillae; (e) part of gena, showing dense short setae; (f) cuticle integument with scattered, short setae and dense minute spicules.