Psen rhyssothoracicus Deng & Ma, 2025

Deng, Yao, Ma, Li & Li, Qiang, 2025, Taxonomic update of Psen Latreille, 1796 (Hymenoptera, Crabronidae), with descriptions of three new species from China, Journal of Hymenoptera Research 98, pp. 971-1003 : 971-1003

3. Psen rhyssothoracicus Deng & Ma sp. nov.

Figs 5 A – J , 6 A – M

Type material.

Holotype. China • ♀; Tibet, Shigatse , Yadong County; 27°37'7.18"N, 88°55'49"E; 3591 m a. s. l.; 25.VII.2018; coll. Shijie DU . Paratypes. 39 ♀♀ 16 ♂♂, same data as holotype . All types deposited in YNAU.

Diagnosis.

The new species is similar to Psen seminitidus van Lith, 1965 sharing with it the following: 1) frons, interocellar area, and vertex medially with dense, fine punctures; scutum with dense, midsize to large punctures; mesopleuron and metanotum with sparse, tiny punctures; 2) petiole with median keel ventrally; 3) pygidial plate narrowly triangular, shiny, laterally with one row of sparse, fine punctures, apex truncate, basally slightly concave; 4) gastral sternum IV with dark brown fasciculate setae on hind margin in male. It differs from Psen seminitidus and other congeners by the following characteristics (characters of P. seminitidus given in parentheses): 1) propodeal pad with dense, slender, oblique longitudinal rugae (with narrow and smooth area); 2) lateral surface of propodeum with oblique, short rugae and fine punctures (with sparse, tiny punctures, without ruga); 3) male antennal articles IV – VII beneath with linear tyloids (articles V – VI or V – VII beneath with linear tyloids); 4) ratio: PL: PW: LT I: WT I: HFL: HTL = 80: 13: 41: 45: 62: 75 in female ( PL: PW: LT I: WT I: HFL: HTL = 59: 11: 41: 50: 60: 70).

Description.

Female. Body length 9.7–12.0 mm. Black; mandible apically reddish brown; wing veins and claws dark brown. Appressed setae on clypeus silvery; vertex and scutum with appressed long, dense, pale brown pubescence; mesopleuron, legs, propodeum and petiole with dense, long, silvery pubescence (Fig. 5 A, B ).

Head. Clypeus with dense, fine punctures, clypeal middle lobe with shallow, arcuate emargination, side with two square teeth, basal half of clypeal disk moderately elevated (Fig. 5 C ). HW: HLF: AOD: WAS: IAD = 90: 71: 6: 8: 12. Mandible bidentate apically, broad and blunt, wide basally: medially: apically = 19: 9: 5. Interantennal tooth moderately elevated, apex slightly acute; frontal carina complete, inconspicuous, extending from median ocellus to apex of interantennal tooth (Fig. 5 C ). Scape slightly bent, pedicel partially concealed within scape, relative lengths of articles III – XII = 20–25, 13–14, 13–14, 12–13, 11–12, 10–11, 10, 10, 10, 14; article III approximately 3.3–4.2 × as long as wide apically, article IV about 1.8–2.0 ×, article XII about 1.4 ×, respectively (Fig. 5 D ). Frons, interocellar area and vertex medially with dense, fine punctures, interspaces less than puncture diameter; lateral ocellar area and vertex with sparse, fine punctures, interspaces equal to or slightly larger than puncture diameter (Fig. 5 C ). Ocellar area moderately raised, area between ocelli with shallow, longitudinal sulcus, behind postocelli without transverse sulcus, vertex behind postocelli not raised, occipital carina smooth (Fig. 5 E ). HW: HLD: POD: OOD: OCD = 90: 35: 12: 15: 17.

Thorax. Scutum with dense, fine to midsize punctures, interspaces 1–2 × puncture diameter. Anterior admedian lines slightly expanded, backward parallel, parapsidal lines and notauli nearly parallel (Fig. 5 F ). Scutellum with dense, midsize punctures, interspaces equal to or larger than puncture diameter, metanotum with sparse, tiny to fine punctures (Fig. 5 G ). Mesopleuron shiny, with sparse, tiny punctures, posteriorly with sparse, inconspicuous longitudinal striae (Fig. 5 H ). Mesosternum with short acetabular carina, longitudinal medioventral carina slightly conspicuous, medially with many transverse carinae. Propodeal enclosure broadly semicircular, slightly depressed, shining, laterally with some slightly inconspicuous, longitudinal carinae; propodeal pad with dense, slender, oblique longitudinal rugae (Fig. 5 G ). Posterior surface of propodeum with irregular, slightly conspicuous reticulate ridges reaching propodeal enclosure, medially with deep sulcus reaching enclosed area, above sulcus with two or three transverse carinae (Fig. 5 I ). In profile, dorsal surface of propodeum together with posterior surface nearly obtuse angle, lateral surface of propodeum with slightly dense, tiny punctures, upper with oblique, short rugae (Fig. 5 H ). Second recurrent vein received by second submarginal cell near apically (Fig. 5 B ). Hind tibia with row of long thick, pale yellow spines on outer surface.

Gaster. PL: PW: LT I: WT I: HFL: HTL = 80: 13: 41: 45: 62: 75. Petiole nearly quadrate in cross section, slightly bent upwards basally, slightly widened backwards, width apically 1.5 × basally, dorsally completely smooth (Fig. 5 A ). Lateral surface with two conspicuous carinae, shallowly depressed (Fig. 5 B ); ventrally with slightly conspicuous median keel, laterally with dense, tiny punctures. Gaster shiny, terga with sparse, tiny punctures (Fig. 5 A, B ). Pygidial plate narrowly triangular, shiny, 1.8–2.1 × as long as wide basally, laterally with one row of sparse and fine punctures, apex truncate, basally slightly concave (Fig. 5 J ).

Male. Similar to female, but slender and smaller, body length 9.2–10.8 mm. Gastral sternum IV with dark brown fasciculate setae on hind margin (Fig. 6 B ). Antennae slenderer than in female, pedicel partially concealed within scape; antennal articles IV – VII beneath with linear tyloids, articles IV and VII shorter, articles V – VI longer; relative lengths of articles III – XIII = 20–25, 18–20, 17–18, 16–18, 16–18, 15–17, 15–17, 15–17, 15–17, 15–16, 19–21; article III approximately 2.5–3.1 × as long as wide apically, article IV about 2.0–2.2 ×, article XII about 1.9 ×, respectively (Fig. 6 D ). In front view, HW: HLF: AOD: WAS: IAD = 83: 60: 5: 7: 10; in dorsal view, HW: HLD: POD: OOD: OCD = 83: 31: 10: 14: 13. Hind tibia with four or five short, thick, brownish spines on outer surface. Venter of petiole with median keel medially and posteriorly, PL: PW: LT I: WT I: HFL: HTL = 68: 12: 36: 40: 56: 68. Genitalia large, dark brown, gonostyle broad and long, inner (or dorsal) margin of apical portion with narrow translucent membrane apically, outer (or ventral) margin and apex provided with fringe of sparse, long setae (Fig. 6 J – M ). Volsellar digitus flattened, hollowed ventrally, with apex round and turned ventrally, inner area slightly produced apically (Fig. 6 J – M ).

Distribution.

China ( Tibet).

Etymology.

The specific name is derived from Greek stem: rhyss - (= rugose) and Greek word thoracicus (= thoracic), referring to the propodeum with some longitudinal carinae and sturdy reticulation.

Figures

Figure 5. Psen rhyssothoracicus Deng & Ma, sp. nov. Female. Holotype. A. Habitus, dorsal view; B. Habitus, lateral view; C. Head, frontal view; D. Antennae; E. Head and pronotum dorsal view; F. Scutum, dorsal view; G. Scutellum, metanotum and propodeum, dorsal view; H. Thorax, lateral view; I. Propodeum, posterior view; J. Pygidial plate, dorsal view. Scale bar: 1 mm.

Figure 6. Psen rhyssothoracicus Deng & Ma, sp. nov. Male. Paratype. A. Habitus, dorsal view; B. Habitus, lateral view; C. Head, frontal view; D. Antennae; E. Head and pronotum dorsal view; F. Scutum and scutellum, dorsal view; G. Metanotum and propodeum, dorsal view; H. Thorax, lateral view; I. Propodeum, posterior view; J. Male genitalia, dorsal view; K. Male genitalia, ventral view; L, M. Male genitalia, lateral view. Scale bar: 1 mm.