The genus Psen can be identified as a member of the tribe Psenini Costa, 1858 within the subfamily Pemphredoninae based on Mandible bidentate apically; occipital carina joining hypostomal carina before midventral line of head; no genal process; scrobe sulus deep, hypoepimeral area raised; omaulus ending as it becomes ventral and turning a little posteriorly; forewing second recurrent vein ending in second or interstitial or third submarginal cell, hindwing M diverging before cu-a; propodeum usually coarsely reticulate posteriorly, sometimes multivariate; dorso-median area of petiole usually smooth, rarely with coarse punctures, without carinae but rarely with a posterior longitudinal groove, no conspicuous laterodorsal setae but abundant strong setae lateroventrally; male gastral sterna III and IV, or only III or IV, with marginal setae posteriorly, rarely without marginal setae, VIII an upturned pseudo-sting; female pygidial plate subtriangular, narrow or broad, sparsely or densely bristled (Bohart and Menke 1976).

Holotype. China • ♀; Inner Mongolia, Helan Mountain; 38°57'45"N, 105°51'8"E; 24.VII.2006; 1833 m elev.; collected by Ming LUO. Paratypes: China • 1♂; same data as holotype; China • 1♀; Yunnan Province, Gaoligong Mountain, Dulong River Tunnel; 27°50'56"N, 98°28'3"E; 15.VII–2.VIII.2020; 2824 m elev.; collected by Lang YI; China • 1♂; Shaanxi Province, Yan’an City, Ganquan County, Liulimao; 36°10'3"N, 109°21'26"E; 5.VII.1971; 1077 m elev.; collected by Jikun Yang. All types deposited in YNAU.

The new species is similar to Psen seminitidus van Lith, 1965, but differs from it and other congeners by the following characteristics (characters of P. seminitidus in parentheses): 1) the posterior surface of the propodeum lacks an oblique longitudinal ridge (the posterior surface of the propodeum has weakly oblique longitudinal carinae); 2) flagellomeres VII–X have linear tyloids beneath in the male (flagellomeres V–VI or V–VII beneath have linear tyloids); 3) the female POD: OOD: OCD = 12: 17: 21 (the female POD: OOD: OCD = 12: 13: 15); 4) the female PL: PW: LT I: WT I: HFL: HTL = 80: 14: 52: 64: 71: 88 (the female PL: PW: LT I: WT I: HFL: HTL = 69: 11: 41: 50: 60: 70); 5) the ocellus and vertex areas feature dense, midsized to large punctures (the ocellus and vertex area feature dense, fine punctures); 6) the scutum has dense, fine punctures anteriorly, dense and midsized to large punctures medially and posteriorly (the scutum has dense, fine punctures); 7) the petiole lacks a median longitudinal keel ventrally in the female (the petiole has median longitudinal keel); 8) the second recurrent vein ends in the third or interstitial submarginal cell (the second recurrent vein ends in the second submarginal cell).

Female. Body length 11.0–11.8 mm. Black; mandible and pygidial area apically reddish brown; fore and mid tarsi dark brown. Appressed setae on clypeus golden or silvery, vertex, scutum, scutellum, and metanotum with long, dense, pale yellow pubescence. Setae on mesopleuron, legs, propodeum, and petiole mid length and silvery (Fig. 1A, B).

Figure 1. 

Psen fronistriatus sp. nov., holotype ♀ A habitus, dorsal view B habitus, lateral view C head, frontal view D antennae E head, pronotum and scutum, dorsal view F scutellum, metanotum and propodeum, dorsal view G thorax, lateral view H propodeum, posterior view I left wing J pygidial plate, dorsal view. Scale bars: 1 mm.

Head. In frontal view, clypeus with dense, fine punctures except margin, mid portion prominent with arch shallow emargination medially, basal 1/2 of clypeal disk moderately convex. HW: HLF: AOD: WAS: IAD = 102: 78: 10: 8: 14. Mandible bidentate apically, broad, blunt; width basally: medially: apically = 18: 10: 3. Interantennal tooth conspicuous, high, apex obtuse or slightly acute; frontal carina weak and reaching interantennal tooth around median ocellus (Fig. 1C). Scape of antennae slightly bent, relative lengths of joints III–XII = 24–26, 16–17, 15–16, 15, 13–14, 12–13, 11–13, 11–12, 11–12, 16–17; joint III ~ 3.4–4.3× as long as wide apically, joint IV with 2.0–2.4×, joint XII with 1.8–1.9× (Fig. 1D). Frons shiny with dense, fine to midsized punctures, and below anterior ocellus with weak longitudinal ridges (Fig. 1C). In dorsal view, ocellus and vertex area shiny, with dense, midsized to large punctures, interspaces larger than frons; ocellar area not raised, behind postocelli with shallow sulcus, vertex behind postocelli region not raised, occipital carina without longitudinal ridge (Fig. 1B, E). HW: HLD: POD: OOD: OCD = 102: 36: 12: 17: 21.

Thorax. Scutum with dense, fine punctures anteriorly, dense, midsized to large punctures medially and posteriorly, interspaces 1–2× as wide as diameter of puncture. Admedian lines and notauluses weak, nearly parallel (Fig. 1F). Scutellum with dense, fine punctures, metanotum with sparse, microscopic punctures (Fig. 1F). Propleuron with five or six short oblique striae, epicnemial areas shiny, with sparse, microscopic punctures, omaulus ending as it becomes ventral and below normally curved backwards. Mesopleura shiny with sparse, microscopic punctures, posteriorly without longitudinal striae (Fig. 1G). Mesosternum without acetabular carina, with slightly strong, longitudinal medioventral carina, medially with one or two transverse carinae. Enclosed area of propodeum depressed, bordered by a narrow horizontal area which is distinctly separated from back of propodeum, horizontal area slightly wider on either side of sulcus, laterally with some sturdy oblique longitudinal carinae; propodeal pad with a smooth area, slightly wider on sides and narrower in middle (Fig. 1F). Posterior surface of propodeum with sturdy reticulation, medially with deep sulcus reaching enclosed area, upper of sulcus with three or four transverse carinae (Fig. 1H). In profile, dorsal surface of propodeum with posterior surface nearly obtuse angle, upper lateral surface of propodeum with oblique, short rugae (Fig. 1G). Second recurrent vein ending in third or interstitial submarginal cell (Fig. 1I). Hind tibia with a row of long, thick, brownish thorns on outer surface (Fig. 1B).

Gaster. PL: PW: LT I: WT I: HFL: HTL = 80: 14: 52: 64: 71: 88. Petiole nearly quadrate in cross section, slightly bent upwards basally, slightly widened backwards, width apically 2.2× basally, dorsally completely smooth (Fig. 1B, F). Lateral side with two slender longitudinal carinae and deeply depressed (Fig. 1B); ventrally without median longitudinal keel. Gaster shiny, terga with sparse microscopic punctures. Pygidial area elongate-triangular, coriaceous, 1.8–2.1× as long as wide basally, laterally one or two rows of coarse, midsized punctures and stiff bristles, apex truncate, slightly concave in middle, basally not convex (Fig. 1J). Sterna smooth.

Male. Similar to female, but body slender, smaller, body length 9.0–11.0 mm (Fig. 2A, B). Mandible, fore and mid tibiae, and tarsi dark brown. Vertex and scutum with long, dense, palely yellow pubescence (Fig. 2C). Gastral sterna III and IV without fasciculate setae on hind margin (Fig. 2B). Clypeus mid prominent portion with arch shallow emargination in middle, two triangular protections in both sides; partially covering labrum. Frons shiny with dense, fine to midsized punctures, and below anterior ocellus with indistinct longitudinal ridges (Fig. 2C). Ocellar area slightly raised (Fig. 2A). Antennae slenderer than female, pedicel partially concealed within scape (Fig. 2A); flagellomeres VII–X beneath with linear tyloids; relative lengths of joints III–XIII = 21–24, 18–20, 17–20, 17–20, 17–19, 16–18, 15–16, 17, 16, 15–17, 20–21; joint III ~ 2.6–3.0× as long as wide apically, joint IV 2.1–2.5×, joint XII 1.6–2.0× (Fig. 2D). In frontal view, HW: HLF: AOD: WAS: IAD = 81: 61: 7: 8: 10; dorsal view, HW: HLD: POD: OOD: OCD = 81: 32: 11: 15: 16 (Fig. 2C). Hind tibia without long, thick, brownish thorns on outer surface (Fig. 2B). Petiole ventrally with median longitudinal keel medially and posteriorly, PL: PW: LT I: WT I: HFL: HTL = 70: 11: 43: 46: 53: 60. Genitalia large, yellowish brown, gonostyle slender and long, apical portion with inner (or dorsal) 1/2 turned into a semitransparent membrane, outer (or ventral) margin and apex provided with a fringe of sparse long setae (Fig. 2I–L). Volsella divided into two branches medially, dorsal and ventral, each roundly curved and united with each other again at base of apical elongate body, cuspis flattened, hollowed ventrally, with apex gently rounded and turned ventrally, slightly produced on inner apical area.

Figure 2. 

Psen fronistriatus sp. nov. ♂ A habitus, dorsal view B habitus, lateral view C head, frontal view D antennae E head, pronotum and scutum, dorsal view F scutellum, metanotum and propodeum, dorsal view G propodeum, posterior view H thorax, lateral view I male genitalia, dorsal view J male genitalia, ventral view K, L male genitalia, lateral view. Scale bars: 1 mm.

China (Inner Mongolia, Shaanxi, Yunnan).

The specific name is derived from two Latin words: froni - (= frons) and -striatus (= striate), referring to the upper frons weakly striate.

Holotype. China • ♀; Guangdong Province, Ruyuan County Nanling National Nature Reserve; 24°56'15"N, 113°0'40"E; 26.VI–28. IX.2021; 1278 m elev.; collected by Institute of Zoology, Guangdong Academy of Sciences. Paratype: China • 1♀; Guangdong Province, Fogan County, Guanyin Mountain; 23°58'13"N, 113°33'49"E; 15–16.IX.2007; 184 m elev.; collected by Zaifu XU. All types deposited in YNAU.

The new species is similar to Psen leclercqi van Lith, 1974, but differs from it and other congeners by the following characteristics (characters of P. leclercqi in parentheses): 1) free margin of the clypeus has three teeth, middle tooth small, lateral teeth large (free margin of the clypeus has two arch-shaped teeth); 2) the frons has coarse, midsized to large punctures, which gradually increase in size from the lower frons to the mid-ocellus (the frons up to ocelli is densely striate-punctate, interstices shining, very narrow margin along the oculi with finer and sparser punctures); 3) the vertex behind the postocellus distinctly raised (not distinctly raised); 4) the mid ocellus postero-laterally has reticulate punctures with coarse interstices (with fine, sparse punctures, interstices shiny); 5) the hind tibia has a row of long, thick, brownish thorns on the outer surface only (with row of short thick thorns and thin, long, white spines); 6) the scutellum has dense, large punctures, the diameter of punctures is 2–3× as the width of the interspaces, although medially the puncture diameter as wide as interspaces (the scutellum is somewhat striate-punctate, interstices larger than punctures); 7) antennae dark brown, yellowish brown apically, while segments III–VII reddish beneath (antennae black but underside of scape and of segments II, III, and XII are reddish brown); 8) the thorax is black (the pronotum dorsally and upper part of foreside, pronotal tubercles, anterior corners of scutum, and upper 2/3 of anterior plate of the mesepisternum are reddish brown).

Female. Body length 13.0–13.6 mm. Black (Fig. 3A, B); mandible apically reddish brown; palpi and antennae apically yellowish brown, antennae dark brown but joints III–VII reddish beneath (Fig. 3C, D). Fore and mid tibiae and tarsi reddish brown with subsequent parts yellowish brown and inner parts black; tarsi, tegulae, veins of wings, and stigma dark brown; margin of gastral terga yellowish brown (Fig. 3A, B). Appressed setae on clypeus golden, frons with less appressed golden pubescence and long erect setae. Long setae on vertex, occiput, collar, posterior margin of pronotum, scutum, scutellum, and metanotum golden (Fig. 3C–E). Mid-length setae on mesopleuron, legs, and propodeum palely yellow, prospectus and ventral side of petiole silvery; gaster with very dense, short, golden pubescence (Fig. 3B).

Figure 3. 

Psen scabrosus sp. nov., holotype ♀ A habitus, dorsal view B habitus, lateral view C head, frontal view D head, pronotum and scutum, dorsal view E scutellum, metanotum and propodeum, dorsal view F thorax, lateral view G propodeum, posterior view H pygidial plate, dorsal view. Scale bars: 1 mm.

Figure 4. 

Comparison of midtarsus features of selected species of Psen A P. ater (Olivier, 1792), ventral view B P. ater (Olivier, 1792), lateral view C P. foveicornis Tsuneki, 1982, lateral view D P. shirozui Tsuneki, 1966, lateral view E P. shirozui Tsuneki, 1966, lateral view F P. bnun Tsuneki, 1971, ventral view G P. simlensis van Lith, 1968, ventral view. Scale bars: 0.5 mm.

Head. In frontal view, clypeus with shiny margin, impunctate, free margin sinuate, with three teeth medially, middle tooth small, lateral teeth large; basal 1/2 of clypeal disk moderately convex (Fig. 3C). HW: HLF: AOD: WAS: IAD = 128: 100: 9: 12: 15. Mandible bidentate apically, broad, blunt; width basally: medially: apically = 26: 15: 5. Carina ending below antennae in low triangular tooth, connected with inner side of antennal sclerites by slender carinae, interantennal tooth distinctly high, apex straight or obtuse; frontal carina distinct and reaching interantennal tooth around median ocellus (Fig. 3C). Scape of antennae slightly bent, relative lengths of joints III–XII = 29, 21, 18, 18, 16, 16, 15, 15, 16, 23; joint III ~ 2.9× as long as wide apically, joint IV with 1.9×, joint 12 with 2.1×. Frons with coarse, midsized to large punctures, diameter of puncture 2–3× as wide as interspaces; lower 2/3 of frons slightly shiny, punctures gradually increase in size from lower frons to mid ocellus (Fig. 3C). In dorsal view, mid ocellus postero-laterally with reticulate punctures, interstices coarse; ocellar area with dense, shallow, large punctures, diameter of puncture approximately as wide as interspaces or slightly more (Fig. 3D). Vertex behind ocellus with deep, large punctures, posteriorly coarser and somewhat striate-punctate, diameter of puncture 2–3× as wide as interspaces, interspaces of vertex slightly larger than frons, barely shiny (Fig. 3D). Ocellus area not raised, behind postocellus with deep sulcus, vertex behind postocellus region distinctly raised (Fig. 3B, D). Occiput with sparse, fine punctures, occipital carina without longitudinal ridge (Fig. 3B, D). HW: HLD: POD: OOD: OCD = 128: 48: 18: 17: 36.

Thorax. Scutum densely and coarsely rugose-punctate, diameter of punctures 2× as wide as interspaces, punctures on both sides arranged in longitudinal trend, interspaces slightly shiny medially; anterior 1/2 of admedian lines slightly expended, posteriorly parallel, parapsidal lines and notauluses nearly parallel (Fig. 3D). Scutellum with dense, large punctures, diameter of puncture 2–3× as wide as interspaces, but diameter of punctures medially as wide as interspaces. Metanotum with dense, oblique carinae, striate-punctate (Fig. 3E). Propleuron with dense, short striae, epicnemial areas densely and finely punctate, omaulus ending as it becomes ventral and below normally curved backwards (Fig. 3F). Mesopleura with dense, midsized to large punctures, interspaces smooth and as wide as diameter of puncture, puncture becoming smaller from top down, upper part of posterior margin of mesopleura with long striae more striking, lower part with fine punctures; subalar area with dense, large punctures, diameter of puncture 2.5× as wide as interspaces, hypo-epimeral area densely, largely striate-punctate (Fig. 3F). Metapleura shiny, with some upper transverse rugae on posterior 1/2 (Fig. 3F). Mesosternum without acetabular carina, with strong, longitudinal medioventral carina; medially with three or four strong transverse carinae. Propodeal enclosure forming a broad triangular shape, enclosed area depressed, shiny, laterally with some longitudinal carinae, medially with irregular carinae; propodeal pad with dense, slender, oblique longitudinal rugae; posterior surface of propodeum with irregular reticulate ridges reaching enclosed area (Fig. 3G). In profile, dorsal surface of propodeum together with posterior surface nearly arc-shaped, lateral surface of propodeum with oblique, short rugae and fine punctures (Fig. 3F). Second submarginal cell receiving first recurrent vein at approximately medially; second recurrent vein ending in second submarginal cell (Fig. 3A). Femora heavy, hind tibia with a row of long, thick, brownish thorns on outer surface (Fig. 3B).

Gaster. PL: PW: LT I: WT I: HFL: HTL = 80: 17: 77: 87: 82: 70. Petiole nearly quadrate in cross section, slightly bent upwards basally, widened backwards, width apically 1.8× basally, dorsally completely smooth (Fig. 3B, E). Lateral side with two slender longitudinal carinae, deeply depressed medially (Fig. 3B); ventrally with an indistinct, blunt, median longitudinal keel, two sides with dense, fine punctures. Gastral terga I and II with sparse, microscopic punctures, interspaces 2× as wide as diameter of puncture; terga III and IV with dense, fine punctures medially and posteriorly, interspaces as wide as diameter of puncture, but basally 1/3 of tergum III and basally 1/4 of tergum IV smooth, impunctate. Pygidial area elongate-triangular, polished, 1.7× as long as wide basally, laterally with one or two rows of coarse punctures and stiff bristles, apex truncate, slightly concave medially (Fig. 3H). Sterna wholly with sparse, fine punctures except sternum II with dense, fine to midsized punctures.

Male. Unknown.

China (Guangdong).

The specific name from Latin word: scabrosus (= scabrous), referring to the head and thorax with large, scabrous punctures.