Cercobarcon Tobias 1979

Austin, Andrew D. & Fagan-Jeffries, Erinn P., 2020, A new species of the enigmatic Australian endemic family Trachypetidae (Hymenoptera: Ichneumonoidea): Cercobarcon lasallei sp. n., Journal of Natural History 54 (9), pp. 553-563 : 554-555

Genus Cercobarcon Tobias 1979

Type

Cercobarcon rieki ; Tobias, 1979: 75 (by original designation), ANIC (examined).

Cercobarcon: van Achterberg, 1984: 52 ; Naumann, 1991: 946; Austin et al. 1993:113; Quicke et al. 2020: 7.

Diagnosis

Occipital carina well developed; maxillary palps 4-segmented, labial palps 3-segmented; tarsal claws pectinate; fore wing vein 1-SR+M incomplete in basal half, SR1 evenly curved so that marginal cell is acute distally; hind wing vein 1-CU straight; spiracles approximately one-quarter length of propodeal lateral margin or less; in dorsal view metasoma fusiform in shape, terga 2 and 3 not forming a carapace, terga 4 – 6 visible dorsally.

Comments

Cercobarcon can be separated from Trachypetus most easily by the latter having a pedunculate metasoma which forms a carapace, and from Megalohelcon by this genus having an incomplete occipital carina, larger propodeal spiracles (0.35 greater than the medial length of the propodeum), simple claws, and fore wing vein CU-1 curved. The genus is known from five species, including the one described here. It is found broadly across the arid zone from central Queensland to the western margin of the continent, with two species occurring on Cape York Peninsula. The genus is apparently absent from the eastern coastal margin, and temperate/Mediterranean south-east and south-west corners of the continent. However, given that specimens are rarely collected, the distribution of the genus may be broader than is currently documented.

Key to species of Cercobarcon

1. Lower margin of clypeus evenly curved or at most very slightly indented medially ( Figure 1 (a))................................................................................................................................................. 2

- Lower margin of clypeus deeply sinuate or bilobed ( Figure 1 (b,c)).................................... 4

2. Fore wing vein 1-SR+M with small terminal swelling ( Figure 3 (b,e)); dorsal head, scutum and scutellum dark brown to black .................................................................................................. 3

- Fore wing vein 1-SR+M without small terminal swelling ( Figure 3 (c,d)); dorsal head, scutum and scutellum red-brown.............................. .............................. C. rieki Tobiası 1979

3. Posterior marginal carina of propodeum slightly sinuate ( Figure 4 (b)); metanotum anteromedial area without medial longitudinal carinae, posteromedial area flat ( Figure 4 (b)); body all black, except propodeum which is brown-black................................ ..................................................................... C. niger Austinı Wharton and Dangerfieldı 1993

- Posterior marginal carina of propodeum evenly curved ( Figure 4 (a)); metanotum anteromedial area foveate, with several medial longitudinal carinae, posteromedial area slightly depressed ( Figure 4 (a)); dorsal head, scutum and scutellum dark brown, propodeum red-brown, metasoma dark brown, T1 more red-brown than T2 – T6............ ..................................................................................................................................... C. lasallei sp. nov.

4. Clypeus deeply sinuate ( Figure 1 (b)); postscutellar depression evenly crenulated; propodeum rugose-punctate, with irregular slightly coarser carina............................................... .................................................................... C. grossi Austinı Wharton and Dangerfieldı 1993

- Clypeus bilobed ( Figure 1 (c)); postscutellar depression with strong medial carina and much fainter lateral crenulae; propodeum with strong medial and lateral carinae, background sculpturing varying from almost smooth to rugose-punctate.......................... ............................................................. C. bilobatus Austinı Wharton and Dangerfieldı 1993

Figures

Figure 1. (a) Cercobarcon rieki Tobias, 1979, anterior head showing shape of the clypeus; (b) Cercobarcon grossi Austin, Wharton and Dangerfield, 1993, lower face showing the sinuate shape of the clypeus; (c) Cercobarcon bilobatus Austin, Wharton and Dangerfield, 1993, lower face showing the bilobed shape of the clypeus.

Figure 3. Cercobarcon lasallei sp. nov., ♀ holotype: (a) fore and hind wing; (b) fore wing submarginal cell showing incomplete vein 1-SR+M with small terminal swelling; Cercobarcon rieki Tobias, 1979: (c) ♀ paratype from Western Australia, showing vein 1-SR+M without a terminal swelling; (d) ♀ holotype, showing submarginal cell with incomplete spurious areolet; (e) Cercobarcon niger Austin,Wharton and Dangerfield, 1993: (e) ♀ holotype showing incomplete vein 1-SR+M with small terminal swelling.

Figure 4. Metanotum and propodeum: (a) Cercobarcon lasallei sp. nov., ♀ holotype; (b) Cercobarcon niger Austin, Wharton and Dangerfield, 1993, ♀ holotype; (c) Cercobarcon rieki Tobias, 1979, ♀ holotype; (d) Cercobarcon lasallei sp. nov., ♀ holotype, lateral view of posterior metasoma.