Dirhinus quadrhinus Delvare, 2018

Delvare, Gérard & Copeland, Robert S., 2018, Four-horned wasps, description of some remarkable Dirhinus (Hymenoptera, Chalcididae) from Kenya, with a discussion of their taxonomic placement, Zootaxa 4374 (3), pp. 301-349 : 326-328

publication ID	https://doi.org/ 10.11646/zootaxa.4374.3.1
DOI	https://doi.org/10.5281/zenodo.5970458
persistent identifier	https://treatment.plazi.org/id/03C97E04-EA00-FFB6-CA86-4547FF49ABA0
treatment provided by	Plazi
scientific name	Dirhinus quadrhinus Delvare
status	sp. nov.

Treatment

Dirhinus quadrhinus Delvare sp. nov.

( Figs 6 View FIGURES 3–8 , 18 View FIGURES 17–20 , 28 View FIGURES 21–30 , 85 View FIGURES 85–98 , 112–118 View FIGURE 112 View FIGURES 113–118 ) ( Tables 3 and 4)

Registered in ZooBank, http://zoobank.org/NomenclaturalActs/AE6BE690-33A0-4ADA-9CA5-ADF7F88B3069

Material examined. Holotype ♀. KENYA: Eastern Province, Samburu National Reserve, nr. Ewaso Ng'iro River , 874 m, 0.56797°N 37.53563°E, 24.VII-07.VIII.2007, Malaise trap, riverine forest, next to headquarters. R. Copeland leg. [F01] [ NMK] GoogleMaps .

Condition of holotype. Specimen complete, glued on rectangular card. Fore right leg [except coxa], left wings and hind leg glued separately.

Etymology. The name refers to the outstanding character of the head, bearing four horns.

Description of female holotype. Body length 4.2 mm. Body black including labrum, mandibles, all coxae and metafemur. Antenna up to second flagellomere, fore and mid legs except coxae, hind tarsus and venation, brownish testaceous ( Fig. 113 View FIGURES 113–118 ). Wings hyaline. Setae on entire surface of fore wing and beyond venation on hind wing, dark; setae white behind venation on hind wing. Setae generally thin and suberect except on pronotum, mesoscutum, axillae and basal half of mesoscutellum where lanceolate, thick and adpressed.

Head 0.93× as wide as long and 0.84× as high; eye 1.28× as long as high; temple 0.63× as long as eye, with convex lateral outline. Genal carina visible from above. Occiput, vertex and dorsal surface of the four horns densely punctured. Setae on occiput lanceolate, adpressed and proclinate; setae on vertex thin and short, no longer than diameter of punctures. Head with four horns; in dorsal view apex of outer horn broadly rounded, that of inner horn more narrowly so, and apex of inner horn extending past that of outer horn ( Fig. 114 View FIGURES 113–118 ); lateral margin of outer horn almost adjacent to inner margin of eye, separated from it by a row of small punctures only; all horns with a narrow coriaceous strip along their margins; inner horns quite broad, separated by a moderately long scrobal depression; inner horn length (IHL) 1.44× as long as distance from end of scrobal depression to median ocellus ( Fig. 114 View FIGURES 113–118 ) and 1.33× as long as ocular-ocellar distance; inner edges of inner horns diverging at a very acute angle, of approximately 20°. Frontovertex 2.82× as wide as IHL. Ocelli forming together a slightly acute angle. Distance from median ocellus to lateral ocellus about as long as ocellar diameter. Distance between lateral ocelli 1.59× as long as that of the inter-ocellar distance. Posterior outline of head forming a regularly convex and semi elliptic curve. Anterior margin of horns without teeth, forming, with dorsal margin, an acute angle, of about 60° for inner horn and 45° for outer horn. Sculpture and setation of gena identical to that of vertex. Faint preorbital ridge present along almost entire height of eye, isolating an admarginal row of punctures ( Fig. 115 View FIGURES 113–118 ). Outer margin of antennal scrobes straight. Mandible grooved both on outer and inner sides, with teeth broadly rounded at apex; outer groove bearing 4 long and thin setae, the inner one with 8–10 long setae, the setae towards apex of mandible closely set. Labrum much higher than wide, depressed on disc and with 3 long setae on either side. Clypeus as a bulging surface about as wide as high and bearing 2 long setae on either side, oriented straight forwards. Clypeus bordered on either side by a stripe of 4 or 5 piliferous punctures and, more laterally, by a moderately large fovea. No malar groove or carina. Lateral outline of gena distinctly convex (as Fig. 143 View FIGURES 141–147 ). Genal margin forming an acute and sharp angle with lateral edge of oral fossa. Sculpture and setation of adscrobal area as for vertex but setae along oral margin longer and thicker. Entire surface of scrobal depression finely and superficially reticulate.

Antenna ( Fig. 116 View FIGURES 113–118 ). Scape linear, inflated towards base. Combined length of pedicel plus flagellum 0.91× as long as head width. Pedicel elongate, 2.1× as long as wide. All flagellar segments transverse, second flagellomere [= 1 st funicular segment] 0.81× as long as wide and tapering basally; followings segments progressively decreasing in relative length, with 8th flagellomere [= last funicular segment] 0.62× as long as wide and 1.33× as wide as 2nd flagellomere. Setation of flagellum short and adpressed, each segment with one row of elongate sensilla. Clava ovoid, narrowly rounded at apex and bearing a small apical area of micropilosity.

Mesosoma relatively short, only 1.46× as long as wide, dorsally flattened ( Figs 112–113 View FIGURE 112 View FIGURES 113–118 ). Pronotal collar transverse, progressively merging to collus, its sides virtually straight; puncturation uniform, in 3 transverse rows; setae at least as long as diameter of punctures, reclinate on mesal surface, oriented inwards laterally. Lateral panel of pronotum flat, with a ventral fovea, and 3 vertical rows of punctures, sparse on the mid one. Mid lobe of mesoscutum with smooth anterolateral surfaces, otherwise densely punctured; the lanceolate setae oriented towards a medio-subanterior imaginary point. Notaulus impressed and punctured. Lateral lobe smooth on most of its surface except a few punctures on their disc and admarginal ones along anterior and posterior margins; setae oriented towards a mesal imaginary point of axillae. Axilla densely punctured, the setae oriented towards a central imaginary point. Mesoscutellum 0.78× as long as wide, weakly convex, angulate anteriorly because axillar grooves almost join each other on transscutal line; setae on posterior half of mesoscutellum thinner than on rest of mesonotum; puncturation somewhat sparser than on mid lobe of mesoscutum and missing on oblong mesal surface; small pores, irregularly distributed, visible on interspaces between punctures. Postscutellum bulging. Propodeum appearing dull because of dense secondary areolation on bottom of areolae; setation short, thin and suberect all over; anteromedian areola cordiform, as long as wide, followed by an incomplete and irregular median carina; sublateral areolae trapezoidal, adpetiolar one angulate anteriorly; spiracle situated within a setose fovea; spiracular tooth moderately broadly rounded, not sharp and somewhat raised upwards. Mesepisternum: mesodiscrimenal groove wide but shallow, ventrally truncate and tapering dorsally; adscrobal area, ventral shelf of mesepisternum and metepimeron densely punctured; adscrobal area bearing short, lanceolate and adpressed setae; ventral shelf with long and erect ones; metepimeron with moderately long, lanceolate and suberect setae; femoral scrobe entirely strigose, the longitudinal crests complete even dorsally. Subcoxal tooth on posterior margin of metepimeron not much projecting but sharp. Metepisternum areolate strigose in front of petiolar foramen, widely and faintly reticulate anteriorly, the posterior projection vestigial.

Legs. Procoxa with anterobasal fovea accommodating temple, the fovea carinately margined on outer side; coxa with 2 long setae at base of apical flange on outer side. Profemur thickened. Mesofemur strongly inflated apically. Mesotibia compressed laterally. Metacoxa short, 1.49× as long as wide, finely transversely strigose dorsally, but smooth towards apex; coxa setose anteroventrally, the setation continuing in 2 or 3 rows on ventral margin of outer surface. Metafemur quite broad, 1.57× as long as wide and with strongly convex dorsal margin at base; short basal tooth visible on ventral margin of metafemur before the serrulation; inner basal boss present; disc of femur with sparse punctulation; setae thin and adpressed, at least as long as interspaces between the points. Metatibia, in addition to tarsal sulcus, with a narrow groove tapering apically; tibia with a row of 13 short and adpressed setae visible along edge of carina that margins the sulcus ( Fig. 117 View FIGURES 113–118 ); outer side of tibia moderately densely setose, the setae thin and adpressed.

Wings. Fore wing 2.74× as long as wide; marginal vein 0.83× as long as costal cell. Basal and cubital folds bare; Rs setose. Basal cell bare. Costal cell with 15–17 setae on underside, aligned on apical half; setae shorter and irregularly distributed at base of cell. Marginal cell with 10 irregularly distributed setae. Setation sparse on rest of wing. Two sensilla placodea at apex of submarginal vein, stigmal vein with 4 aligned sensilla.

Metasoma. Petiole with dorsal surface transverse, 2.15× as wide as long, with low submedian ridges and sloping backwards ( Fig. 118 View FIGURES 113–118 ); anterior margin strongly emarginate mesally; ventral part with weakly protruding basal tooth, rest of surface areolate rugose and with posterior furrow.

Gaster 2.02× as long as wide, 1 st gastral tergite large, 0.62× as long as gaster, longitudinally strigose on basal third, the outer ridges arcuate, stronger than other ridges; seven primary ridges (joining the basal transverse carina) and 10 secondary crests visible; strigose surface smooth between ridges; tergite punctulate on a subapical transverse stripe, with sparse setae laterally and apically. Following tergites much shorter; posterior margin of GT2 straight, the following margins progressively more concave; each tergite bearing a row of setae. Hypopygium almost reaching apex of gaster, bearing 2 long and diverging thin setae.

Male. Unknown.

Diagnosis. Body without extremely long setae. In dorsal view, apex of inner horn extending past that of outer horn. Inner horns moderately long, their inner edges diverging at a strongly acute angle. Preorbital ridge present. Pedicel relatively long. Dorsal surface of petiole transverse, with low submedian ridges (raised carinae visible in D. gigasetosus , D. kambae and D. leakeyorum ), sloping distinctly backwards; anterior margin strongly emarginate mesally.

Recognition. This species can be recognized by the following features. The absence of extremely long setae separates it from D. gigasetosus . The presence of a preorbital ridge distinguishes it from D. leakeyorum . The proportions of the pedicel (2.1× as long as wide), and the inner horns only moderately long, with their inner edges diverging at a very acute angle (approximately 20° only), separate it from all other species. Additionally, the transverse dorsal surface of the petiole with its low submedian ridges differentiates it from D. gigasetosus , D. maasaii and D. leakeyorum .

Distribution. The species is known only from its type locality, in Kenya.

Host(s). Unknown, but probably Diptera based on the behaviour of other species in the subfamily to which it belongs.