Cercobarcon lasallei, Austin & Fagan-Jeffries, 2020

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 : 557-562

Cercobarcon lasallei sp. nov.

( Figures 2 , 3 (a,b), 4(a,d))

http://www.zoobank.org/urn:lsid:zoobank.org:act:F912578E-6257-4C67-8914-

C54B11AC9E21

Description (female)

Body and colour. Length of body 20.0 mm; ratio of antenna to body 1.1; ratio of length of fore wing to body 0.75; ratio of length of metasoma to mesosoma 1.3; body dark orange-brown, dorsal head and scutum/scutellum slightly darker than propodeum, base of T1 black; surface densely covered in fine white setae which are slightly longer on propodeum; wings very slightly infuscate; venation darkly pigmented.

Head. Medial horn on lower face broadly pointed, circular in cross section, about as high as basal width; lateral carinae on face broad, lower ends not expanded into blunt teeth; face and frons rugose, lower occiput rugose-punctate; dorsal occiput smooth except for micropunctures associated with pilosity; clypeus with lower margin evenly curved; temples bulging postero-laterally, almost reaching level with longitudinal tangent to eye; occiput broadly excavate; length of temple behind eye about 0.35× medial length of head; median ocellus about same size as lateral ocellus, lateral ocelli separated by about 0.8× their diameter, separated from median ocellus by 0.3× their diameter; in lateral view temple same width as eye; mandible with a single tooth; ventral basal surface of mandible with tuft of long setae; sensory structure on basal outer surface of mandibles identical in shape to that of other described Cercobarcon species; antenna longer than length of body, with approximately 86 flagellomeres.

Mesosoma. Dorsal surface of pronotum transversely wrinkled; mesoscutum slightly wider than long (4.0:3.5), broadly rounded anteriorly, antero-lateral margin slightly emarginate at point of notauli, covered with fine setae; medial and lateral lobes virtually smooth except for micropunctures associated with pilosity, medial lobe convex with ill-defined medial longitudinal carina; notauli smooth but very faintly crenulate; scutellar sulcus represented by two deep medial foveae; scutellum with long white pilosity medially, lateral indented areas smooth, without carinae, postscutellar depression divided by indistinct carinae; metanotum anteromedial area foveate, with several medial longitudinal carinae, posteromedial area slightly depressed; lateral metasoma smooth, deeply concave, without carinae; propodeum with medial longitudinal carina and few coarse carinae laterally and posteriorly, carinae enclosing spiracles but not forming a small medial areola; propodeal surface otherwise generally smooth anteromedially and rugose laterally, but sculpturing partly obscured by pilosity; spiracles of moderate size, 0.23× medial longitudinal length of propodeum (measured from inner margin of surrounding lip of spiracle); posterior marginal carina of propodeum evenly curved; in lateral view pronotum smooth, with pilosity sparser in dorsal part; mesopleuron mostly smooth except for micropunctures associated with pilosity; epicnemial area faintly crenulate; precoxal groove indicated by broad area of rugose-punctate sculpturing; metapleuron mostly smooth with a few coarse crenulae dorsally; coxae and femora with slightly more sparsely placed setae than on tibiae and tarsi; hind tibia widening from base to apex, at apex about as wide as widest part of hind femur; outer hind tibial spur almost equal in length to inner spur, tarsal claws finely pectinate.

Wings. Fore wing without faint spurious vein between 2-SR and 2-M forming an incomplete areolet (as in M. rieki holotype); proximal end of 1-SR + M distinctly swollen, 2-M slightly angled at point one-third length from proximal end; hind wing with 10 hamuli.

Metasoma. T1 2.2× as long as apical width, slightly longer than T2 + T3, about 0.4× length of metasoma, spiracle anterior of midpoint, 0.35× length of TI from base; border between T2 and T3 clearly indicated by depressed line and by change in density of pilosity; metasomal surface smooth except for micropunctures associated with dense, fine pilosity; pilosity slightly sparser on T1 compared with T2 – T6; hypopygium setose throughout, setae shorter than on ovipositor sheaths.

Male. Unknown.

Diagnosis

Cercobarcon lasallei can be separated from all other species in the genus on the following combination of characters: lower margin of clypeus evenly curved or at most very slightly indented medially; fore wing vein 1-SR+M with small terminal swelling; posterior marginal carina of propodeum evenly curved; median field of metanotum flat in posterior half, anterior depression without medial longitudinal carina; dorsal head, scutum and scutellum dark brown, propodeum red-brown, metasoma dark brown, T1 more red-brown than T2 – T6.

Specimen examined

Holotype, Australia (Queensland): ♀, ‘ Claudie R., near Mount Lamond, Qld, 18 January 1972, D.K. McAlpine, G.A. Holloway ’ ( AMS).

Biology

Unknown.

Etymology

This species is named in honour of our colleague and a close friend of ADA, the late Dr John La Salle.

Distribution

This species is known only from the type locality (Claudie River) in North Queensland ( Figure 5 ) .

Comments

Normally we would not consider describing a species based on a single specimen, but in this case we feel it is justified based on most members of the Trachypetidae being so rarely collected, and that it is clearly different from the other two species to which it is likely to be most closely related, C. niger and C. rieki (see key to species).

Figures

Figure 2. (a) Cercobarcon lasallei sp. nov., ♀ holotype: (a) anterior head; (b) dorsal head; (c) dorsal habitus; (d) lateral habitus.

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 5. Distribution map showing the collection site of the Cercobarcon lasallei sp. nov. holotype.