Diplazon tetragonus ( Thunberg 1824, Ichneumon

Klopfstein, Seraina, 2014, Revision of the Western Palaearctic Diplazontinae (Hymenoptera, Ichneumonidae), Zootaxa 3801 (1), pp. 1-143 : 46-47

Diplazon tetragonus ( Thunberg 1824, Ichneumon )

Ichneumon hortorius Thunberg 1824

Ichneumon ustorius Thunberg 1824

Bassus tricinctus Gravenhorst 1829

Bassus nemoralis Holmgren 1858

Bassus concinnus Cresson 1868

Bassus albicoxus Provancher 1874

Bassus amoenus Provancher 1874

Diagnosis. Fore wing length 3.7–5.2 mm. Antenna in females with 16–17, in males with 16–18 flagellomeres. Face with punctures usually distinct from the background sculpture. Mesopleuron smooth and polished weakly punctate largely restricted to lower half. Propodeum with a full set of carinae enclosing basal, lateral and petiolar areas. Tergite 1 1.0–1.25 times as long as wide in females, 1.2–1.4 in males, tergite 2 0.6–0.75 in both sexes; tergites 2 and 3 mainly rugose and coriaceous, at most with some irregular punctures, especially on tergite 3, the area between the punctures not entirely smooth. Transverse impressions distinct on tergites 1–4. Metasoma dorsoventrally depressed.

Colouration of females. Antenna dark brown. Head and mesosoma black, face with yellow along inner orbits, without yellow central face patch, yellow on clypeus and mouthparts, hind corner of pronotum, tegula, subtegular ridge, shoulder mark, upper mesepimeron; scutellum at least with yellow tip, usually largely yellow. Legs and coxae orange, fore coxa usually dark at extreme base; femora orange; hind tibia black-white-black banded, sometimes apical band with an orange or orange-brown area, hind tarsus dark. Metasoma black.

Colouration of males. As in females but with yellow ventrally on scape and pedicel, antenna often orange below, yellow over entire face, spot on propleuron, epicnemium and part of mesosternum. Fore and mid coxae yellow, hind coxa mainly orange. Tergites 2 and 3 sometimes with light posterior margins, the colour of which can be light brown to orange but never entirely yellow or white.

Material examined. Holotype of Ichneumon tetragonus Thunberg : Sweden, no locality data. 1♂, at UU . Holotype of Ichneumon hortorius Thunberg : Sweden, no locality data. 1♂, at UU . Holotype of Ichneumon ustorius Thunberg : Sweden, no locality data. 1♂, at UU . Lectotype of Bassus nemoralis Holmgren : Sweden, Småland, leg. Boheman. 1♀, at NRM .

Austria (1), Denmark (1), Finland (7), France (1), Germany (8), Hungary (50), Norway (1), Russia (3), Spain (1), Sweden (>100), Switzerland (>100), Turkey (1), United Kingdom (70), USA (1).

Distribution. Holarctic and Oriental.

Figures. Metasoma ♀ ( Fig. 7 B, 18A), hind wing ( Fig. 11 D), fore wing ( Fig. 12 C), clypeus ( Fig. 12 G), hind tibia ( Fig. 12 L).

Notes. This is a rather variable taxon and might not represent a single biological species. Several taxa have already been split from tetragonus in the past, e.g. D. scutatorius and D. pallicoxa , and it is possible that even the remaining taxon still consists of a complex of species.

Figures

FIGURE 7. Macro- and microsculpture of diplazontine metasomas and faces. A – D: tergites 1 – 3 of the metasoma. A. Diplazon scutatorius, smooth and shining between the strong and dense punctures. B. Diplazon tetragonus, with partly rugulous sculputure basally on tergite 2, and coriaceous sculpture on tergite 3, both tergites bearing weak punctures on a smooth background behind the strong transverse impressions. C. Tymmophorus obscuripes, with rugose sculpture on tergites 1 and 2, becoming more coriaceous on tergite 3. D. Woldstedtius holarcticus, with coriaceous tergites and striae basally on tergite 2. E – H: faces showing sculpture and shape of clypeus. E. Sussaba flavipes, with a face that is coriaceous only on the middle elevation. F. Woldstedtius holarcticus. G. Diplazon scutatorius. H. Homotropus signatus. F. – H. all with strongly coriaceous and matt sculpture. Scale bars represent 500 µm.

FIGURE 11. A. Sussaba cognata ♀, first to third segments of metasoma with laterotergites outflexed. B. Promethes sulcator ♀, first to third segments of metasoma with laterotergites outflexed. C. Sussaba erigator ♀, hind wing. D. Diplazon tetragonus ♀, hind wing. E. Sussaba cognata ♀, metasoma. F. Episemura ensata ♀, metasoma. G. Sussaba punctiventris ♀, scutellum. H. Episemura diodon ♀, scutellum. I. Episemura ensata ♀, ovipositor sheath. J. Eurytyloides umbrinus ♀, ovipositor sheath.

FIGURE 12. A. Diplazon laetatorius ♀, mesonotum showing notauli. B. Syrphoctonus tarsatorius ♀, mesonotum. C. Diplazon tetragonus ♀, fore wing. D. Enizemum ornatum ♀, fore wing. E. Promethes sulcator ♀, head. F. Tymmophorus obscuripes ♀, head. G. Diplazon tetragonus ♀, clypeus. H. Tymmophorus suspiciosus ♀, clypeus. I. Daschia brevitarsis ♀, clypeus. J. Campocraspedon caudatus ♀, clypeus. K. Xestopelta gracillima ♀, clypeus. L. Diplazon tetragonus ♀, hind tibia.