Piogaster albina Perkins, 1958

Figs 4, 5, 6

Piogaster albina Perkins, 1958: 264.

Diagnosis.

Piogaster albina can be distinguished from its congeners by possession of the combination of the following: 1) mesoscutum polished, impunctate in most specimens (Fig. 4 E) or punctate anteriorly with at most a few sparse setae laterally and anteriorly; 2) metasomal T 2 – T 5 coarsely, densely punctate (Fig. 5 H) to moderately punctate (Fig. 6 B). P. albina closely resembles P. lucida, however P. albina T 2 – T 5 are coarsely densely to moderately punctate, whereas P. lucida T 2 – T 5 are sparsely punctate anteriorly and laterally and otherwise smooth.

Redescription.

Adult. Female. Body length 4.4–6.8 [5.4] mm. FW length 3.5–4.9 [3.9] mm. Head. Antennae with 20–23 [21] flagellomeres (Fig. 4 A). Clypeus 1.5–2.2 [1.65] × as wide as high, polished, weakly rugulose, with sparse long light brown setae (Fig. 4 C). Face polished, sculpture variable from completely smooth, to smooth laterally and ventrally and weakly rugulose punctate mediodorsally [as in holotype, (Fig. 4 C)], to entirely weakly rugulose punctate, with sparse medium length yellow-white setae. Frons and vertex polished, smooth [as in holotype, (Fig. 4 B)] to coriaceous (Fig. 4 D) but finely densely punctate in some specimens, with sparse to moderately dense short to medium length yellow-white to medium brown setae (Fig. 4 D). Occipital carina complete (Fig. 4 B). MSL 0.7–1.0 [1.0] × as long as BWM. OOD 1.3–1.7 [1.3] × as long as LOD. Mesosoma. Pronotum with epomia absent; polished, smooth (Fig. 6), weakly coriaceous (Fig. 5 A), or weakly rugulose punctate [as in holotype, (Fig. 4 A)], lacking setae or with sparse, medium length yellow setae. Mesoscutum polished, smooth to weakly coriaceous, anterolaterally smooth (Fig. 5 A) to densely punctate, sometimes posteriorly sparsely setose, medially with at most 10 sparse medium to long brown setae (Fig. 4 E). Scutellum polished, smooth, with only a few very sparse, short yellow-white to medium brown setae (Fig. 4 E). Mesopleuron polished, smooth [as in holotype] (Fig. 6 A) or weakly coriaceous (Fig. 5 B), lacking setae centrally, with sparse, medium length, yellow-white setae dorsally, posteriorly and especially ventrally (Fig. 5 B). Metapleuron polished, weakly rugulose, moderately densely punctate with medium length white setae (Fig. 5 C). Propodeum polished, variable sculpture from almost completely smooth (Fig. 6 B) to mostly rugulose [as in holotype] (Fig. 5 D), with sparse long yellow-white setae, setae absent medially. Propodeum with pleural carina complete in most specimens, present and strongly indicated anteriorly (Fig. 5 C), but indistinct and / or sinuous medially to posteriorly in some specimens [including holotype] (Fig. 4 A); lateral longitudinal carina present in posterior 0.2–0.5 [0.5], all other propodeal carina absent (Figs 5 D, 6 B). Wings. Fore wing. Vein Rs + M without ramellus extending conspicuously anteriorly into cell 1 M + 1 R 1 (Fig. 5 F) (at most indicated by a small stub where these two veins meet). Vein 2 rs-m 0.5–1.0 [1.0] × as long as M between 2 rs-m and 2 m-cu (Fig. 5 F). Vein 2 m-cu not thickened or angulate between bullae (Fig. 5 F). Hind wing. Vein 1 / Cu & cu-a inclivous, strongly angled where 2 / Cu intercepts in lower 0.3–0.4 [0.3] (Fig. 5 E), with 2 / Cu ranging from completely tubular to tubular at extreme base and nebulous more apically [as in holotype] to completely nebulous. Metasoma. T 1 polished, anteriorly smooth [as in holotype] to sparsely punctate, medially to posteriorly punctate (Figs 5 G, 6 B), sometimes posterolaterally punctate reticulate, punctures with dense medium length yellow-white setae. T 1 median dorsal carina absent (Fig. 6 B), or present anteriorly but short and weak (rounded) [as in holotype] (Fig. 5 G), 0.1–0.2 [0.2] × length of T 1; dorsolateral carinae variable, completely absent in some specimens, present anteriorly for 0.2–0.4 × length of T 1 [as in holotype], present in posterior 0.3 × length of T 1 in some specimens, absent medially in all specimens (Fig. 5 C). T 2 – T 5 polished, densely to moderately densely punctate, with sparse to dense medium length white setae, T 2 and T 3 laterally punctate reticulate in some specimens (Figs 4 B, 5 H, 6 A, 6 B). T 6 polished, with punctures varying from sparse (Fig. 6 A) to moderately dense (Figs 5 H, 6 C) to dense [dense] (Fig. 4 A), with medium length white setae (Figs 5 H, 6 A, 6 C). T 7 and T 8 polished, smooth (impunctate), with a few short to medium length white to medium brown setae anteriorly and laterally (Figs 4 A, 5 H, 6 A, 6 C). Tergites without grooves or tubercles (Figs 4 A, 5 H, 6 A, 6 C). Ovipositor sheath 0.8–1.0 [0.9] × as long as hind tibia (Fig. 6 C). Colour. Face, frons, and gena medium brown [as in holotype (Figs 4 A – C)] to black (Fig. 4 D). Clypeus medium brown [as in holotype, (Fig. 4 C)] to black, some specimens yellow-brown medially. Malar space medium brown to black, some specimens with yellow-brown spot [as in holotype]. Vertex and occiput medium brown to black [medium brown, (Fig. 4 B)], vertex with long thin irregular shaped yellow [as in holotype (Fig. 4 B)] to red-brown mark (Fig. 4 D). Mandible black with thin transverse basal red-brown stripe or brown basally, red-brown apically with medial transverse black stripe [as in holotype]. Maxillary and labial palps medium to dark brown [medium brown, Fig. 4 C]. Antenna colour uniformly brown-black or with scape and pedicel light to dark brown with pale to medium brown flagellomeres [as in holotype, Figs 4 A, 4 B] (Fig. 4 B). Pronotum uniform medium brown [as in holotype, (Fig. 4 A)] to black (Fig. 6 A), sometimes lighter dorsally (Figs 6 C, 5 A). Tegula light [as in holotype, Fig. 4 B] to medium brown (Fig. 4 E). Mesoscutum medium brown [as in holotype, (Fig. 4 B)] to black (Fig. 4 E), sometimes with yellow to red-brown lateral margins (Fig. 5 A) and yellow to red-brown posteriorly. Scutellum, post-scutellum and axillary troughs uniform medium brown [as in holotype, (Fig. 4 B)] to black (Fig. 4 E). Mesopleuron medium brown [as in holotype, (Fig. 4 A)] to black, sometimes with yellow-brown or red-brown area anteriorly (Fig. 6 C). Metapleuron uniform medium brown [as in holotype] to black. Propodeum uniformly medium brown [as in holotype, (Fig. 4 B)] to black (Fig. 6 B). Wings hyaline, veins light brown transparent, SC + R medium brown, stigma variable from light brown transparent [as in holotype, (Fig. 5 E)] to medium brown. Fore, middle and hind coxae medium brown [as in holotype] to black, white apically in some specimens, trochanters medium brown [as in holotype, (Fig. 4 A)] to black (Fig. 5 C), white apically in most specimens, femur and tibia yellow-white with medium brown to black longitudinal stripe on dorsal and ventral surfaces, fore tibia without ventral stripe in most specimens, tarsi yellow-white, light brown to black on dorsal surface (Fig. 4 A). Metasomal tergites variable, uniform yellow-brown (Fig. 5 H), medium brown [as in holotype, (Figs 4 A, 4 B)] (Fig. 4 B) or brown-black (Fig. 6 A). Ovipositor sheath variable, medium brown with a yellow-white band from 0.2–0.4 [as in holotype, (Fig. 4 A)], uniform medium to dark brown (Fig. 6 A), or medium brown fading to white at apical 0.2 (Fig. 6 C).

Male. A male was described by Aubert (1963) as P. albina because it was collected in the same locality on the same day as four female P. albina. We have examined this male and whereas we could not refute Aubert’s identification, we also could not find any characters that would associate it unequivocally with females of P. albina.

Distribution.

Fig. 26. Western Palaearctic: England (Shaw 2006), France (Aubert 1963), Germany (Perkins 1958), Hungary (current study, new record), Poland (Sawoniewicz 1978), Romania (Pisica 2002), Spain (del Castillo 1994), Sweden (personal communication, Harald Havnås, new record). A male Piogaster specimen from Austria was listed as P. albina in Kazmierczak (1990), but this specimen was not examined. With so little known about males of Piogaster and no justification for identification of this male as P. albina, this record cannot be confirmed.

Biology.

Host unknown. Reared from an oak marble gall, A. kollari (Hymenoptera: Cynipidae) in southern England (Shaw 2006), with the assumption that the host of P. albina had entered the gall after being parasitized.

Material examined.

Holotype. Germany • 1 ♀; B. M. Type Hym. 3 b. 2023; Ruthe Coll. 59.101; NHMUK 010880786; [NHMUK].

Condition of type: Metasoma detached and glued to a separate point, otherwise intact.

Paratype. England • 1 ♀; Norfolk, King’s Lynn; viii. 1911; Atmore; [NHMUK].

Other material.

England • 1 ♀; Leicester; vi. 1973; Jennifer Owen; [EMUS] • 1 ♀; Goblin Combe, vc 6, Somerset ST 47 65; 5. iii. 2000; D. Gibbs; Em. 6. v. 2000; Emerged from oak marble gall; CNC 310408; [NMS] • 1 ♀; Kent, VC 16, Halling, St. Andrews Lakes centroid; v-vii. 2022, M. C. Townsend; CNC 1754425; [NMS] • 1 ♀; same data as for preceding; [NMS] • 1 ♀; Norfolk, Holme Dunes, site ENDURE_MARRAM_INVERT_12_UK; 13. vii. 2019; 52.97528°N, 0.54713°E; Ruben Van De Walle; Sweep on Ammophila arenaria; coastal dune, marram dominated; [RBINS] (photo only). France • 1 ♀; Vendée, Longeville; 19–26. ix. 1965; J. A. J. Clark; B. M. 1965-489; NHMUK 012850730; [NHMUK] • 1 ♀; FR 44, Notre-Dame-des-Landes, La Freusière (WGS 84); 47.3487°N, 1.7709°W; 16. vii. 2013; Naturalistes en lutte - PM 1; Genbank: SRX 14790939; ICH_PIMP_00026; [USNM] (photo only) • 2 ♀; Bouches-du-Rhône, Fos-sur-Mer; 13. ix. 1962; J. A. Aubert; [MZLS] (photo only) • 1 ♀; Pont du Gard; 4. vi. 1967; Matile; [MZLS] (photo only). Hungary • 1 ♀; Vas Co., Kétvölgy; 46.88333°N, 16.21667°E; 18. v. 2001; G. Gibson; CNC 842511; [CNC]. Spain • 1 ♀; Cantabria, Trillayo; 20. viii. 1991; Carmen Rey del Castillo; Yellow pan trap; MNCN_Ent 203194; [MNCN]. Sweden • 1 ♀; Gotlands kommun, Roleks; 57.53678°N, 18.33788°E; 10. iv – 6. vi. 2005; The Swedish Malaise Trap Project; Malaise trap ID 28; Border between mixed pine forest and open grazed calcareous pasture; [NHRS].

Comments.

There is a great variation in the degree of rugosity of parts of the head, mesosoma and metasoma, especially the face, pronotum and propodeum, from highly rugose as in the specimen from England, Goblin Combe (Fig. 5 D showing propodeum) to highly smooth and polished in the specimen from Hungary (Fig. 6 B). The holotype tends towards more rugosity in these areas (Figs 4 A, 4 B).

Aubert named two new forms, form alboclypeata (Aubert 1963) and form rufa (Aubert 1969 a). We examined the specimen Aubert (1969 a) references for form rufa and the morphological variation found in this specimen is included in the above description. We examined two of the four females collected at Fos-sur-Mer on September 13, 1962 (the locality where form alboclypeata was collected), but neither of these had a white clypeus, so they were not likely the specimen assigned to form alboclypeata by Aubert (1963). As we did not see this specimen, and Aubert (1963) does not provide a detailed description of the morphology of the form, the morphological variation of this form is not captured in our description. As both were published after 1960, they are considered infrasubspecific categories rather than subspecies (see ICZN 1999: Art. 45.6).