Orancistrocerus thanhnhat, Nguyen & Nguyen & Dang, 2024

Nguyen, Lien Thi Phuong, Nguyen, Anh D. & Dang, Hoa T., 2024, The solitary wasp genus Orancistrocerus from Vietnam, with descriptions of two new species (Hymenoptera, Vespidae, Eumeninae), ZooKeys 1193, pp. 95-110 : 95

Orancistrocerus thanhnhat sp. nov.

Figs 2A-G , 3A-D

Material examined.

Holotype. Vietnam • ♂, Cao Bang, Ha Lang, Thanh Nhat ; 22°42'8"N, 106°39'49"E; alt. 332 m; 18.v.2023; Lien Thi Phuong Nguyen, Cuong Quang Nguyen & Ngat Thi Tran leg.; IEBR.

Diagnosis.

This species can be distinguished from other species in the genus in the following combination of characters: clypeus in frontal view as wide as high, apical margin widely emarginate medially, forming short, blunt teeth on each side, distance between teeth> ½ width of clypeus between inner compound eye margins (~0.55 × width of clypeus between inner compound eye margins); occipital carina conspicuously widened laterally; mesoscutum in dorsal view slightly shorter than wide between tegulae; TI in dorsal view ~2.5 × as wide as long; TII sparsely punctate, interspaces much greater (2-3 ×) than puncture diameter, except at base and at apical margin with interspaces smaller than puncture diameter.

The new species is similar to O. drewseni in that both have TII sparsely punctate centrally, interspaces much greater (2-3 ×) than puncture diameter. However, it differs from O. drewseni in the following characters: mesoscutum in dorsal view slightly shorter than wide between tegulae (mesoscutum in dorsal view longer than wide between tegulae in O. drewseni ); TII with punctures conspicuous (TII with punctures less conspicuous in O. drewseni ); TII not lamellate apically (TII lamellate apically in O. drewseni ); TI-II with narrow, lateral stripes of orange-yellow (TI-II with apical thick yellow bands in O. drewseni ); and digitus gradually narrowed from base to apex, penis valves long, more than 2 × as long as basal apodeme (digitus almost parallel from base to half, then narrowed to apex in O. drewseni ( van der Vecht 1963: fig. 8f); penis valves shorter, less than 2 × as long as basal apodeme ( van der Vecht 1963: fig. 8g)).

Description.

Male (Fig. 3A ): body length 13.2 mm; forewing length 12.5 mm.

Structure. Head in frontal view subcircular, ~1.3 × as wide as high (Fig. 2A ). Vertex sloping down behind lateral ocelli towards occipital carina, without cephalic foveae. Distance from lateral ocelli to apical margin of vertex 2.7 × distance from lateral ocellus to inner compound eye margin (Fig. 2B ). Gena in lateral view much narrower than compound eye, ~0.6 × as wide as compound eye; occipital carina complete, present along entire length of gena, markedly widened laterally (Fig. 2F ). Inner compound eye margins in frontal view convergent ventrally, in anterior view 1.2 × further apart from each other at vertex than at clypeus (Fig. 2A ). Clypeus in lateral view gradually convex from base to apical margin; in frontal view as wide as high (Fig. 2A ), with basal margin almost straight medially and distinctly separated from antennal toruli; apical margin widely emarginate medially, forming blunt short teeth on each side, distance between teeth> ½ width of clypeus between inner compound eye margins (~0.55 × width of clypeus between inner compound eye margins). Mandible with prominent wide teeth. Scape long, ~4.2 × as long as its maximum width, slightly curved; FI long, ~2.3 × longer than wide, FII ~1.5 × as long as wide, FIII ~1.3 × as long as wide, FIV slightly longer than wide, FV-VIII almost as long as wide, FIX ~1.2 × longer than wide, FX small, terminal flagellomere slender, ~2.7 × as long as its basal width, slightly curved (Fig. 2C ). Mesosoma longer than wide in dorsal view (Fig. 2D ). Pronotal carina present, rounded at humeral angle, reaching ventral corner of pronotum. Mesoscutum slightly convex, slightly shorter than wide between tegulae, with depressed and oblique furrows apically, and two carinae laterally at apical one-third (Fig. 2D ) (with middle narrow furrow present at basal one-third). Disc of mesoscutellum convex, in lateral view at same level as mesoscutum (Fig. 2F ), narrowly depressed basally. Metanotum slightly convex. Propodeum (Fig. 2E ) conspicuously excavated medially, with posterior surface distinctly concave, at basal quarter with median carina running to apical margin; border between dorsal and lateral surfaces slightly angled, posterior and lateral surfaces angled. TI in dorsal view narrower than TII, truncate at base (Fig. 2G ); anterior vertical surface of TI slightly convex, with sparse shallow punctures, clearly separated from posterior horizontal surface by carina. TI in dorsal view ~2.5 × as wide as long; TII in dorsal view ~1.1 × wider than long (Fig. 2G ); SII in lateral view slightly depressed basally, then gradually and slightly convex to apical margin, with weak medial furrow at basal half.

Sculpturing. Clypeus with sparse, shallow, large, undefined punctures on disc; border between punctures smooth. Mandible with row of punctures laterally. Frons densely covered with coarse, flat-bottomed punctures; interspaces between punctures narrow and raised to form reticulation. Vertex with coarse punctures, punctures equal in size; gena with punctures similar to those on apical half of vertex, punctures smaller and less coarse in basal half, with several short transverse conspicuous striae laterally; occipital carina markedly widened laterally (Fig. 2F ). Pronotum with punctures less coarse than those on vertex. Mesoscutum covered with flat-bottomed punctures, punctures equal in size, interspaces between punctures forming reticulation that tends to form longitudinal carina centrally; mesoscutellum with punctures similar to those on pronotum, punctures on metanotum denser than those on mesoscutellum, interspaces between punctures narrow and raised to form reticulation. Mesepisternum with flat-bottomed punctures, punctures coarser and larger than those on pronotum posterodorsally, smooth anteroventrally; border between posterodorsal and anteroventral parts distinct, without epicnemial carina. Dorsal part of metapleuron largely smooth and with several short and conspicuous striae, ventral part largely smooth, with sparse and shallow punctures laterally. Propodeum with coarse, large, flat-bottomed punctures dorsally; punctures are shallower, smaller, and sparser laterally; angle between dorsal and lateral parts of propodeum somewhat rounded; posteriorly surface of propodeum with punctures at upper and lateral parts, with oblique weak carina at lower part, and with a large smooth area centrally. Tegulae with minute punctures. Metasomal segment I covered with sparse and conspicuous punctures dorsally, fine and sparse punctures dorso-anteriorly, distance between punctures greater than puncture diameter; TII with punctures shallower than those on TI, punctures near apical margins deeper, larger and coarser than those on other parts of the tergum, interspaces between punctures greater (~2-3 ×) than puncture diameter at central part; TIII-V with punctures conspicuous and deep, smaller than those on TII; TVI and TVII with minute punctures; SII with sparse punctures, punctures deeper and larger than those on margins of TII laterally; SIII-V with punctures smaller and shallower than those on SII; SI with narrow basal part smooth.

Color. Black; clypeus yellow, except for black margin; yellow spot near base of mandible; beneath scape yellow; flagellomeres beneath light brown; two short, orange-yellow bands at apical margins of TI and TII. Propodeal valvulae dark brown. Middle coxae with two short, yellow strips; hind coxae with a yellow spot. Wings brown, transparent; veins dark brown (Fig. 3A ).

Pubescence. Head and thorax with long, dense, yellow setae; metasoma with short, dense, yellow setae.

Female. Unknown.

Genitalia. As in Fig. 3B-D . Parameral spine lacking setae. Volsella flattened, spatulate, wide on inner aspect, and without setae apically. Digitus gradually narrowing from base to apex, all setose (Fig. 3B ). Penis valve long, ~2.2 × as long as basal apodeme (Fig. 3C ), in profile apical part conspicuously produced into triangular lobe (Fig. 3D ).

Distribution.

Northern Vietnam.

Etymology.

The specific epithet is a noun in apposition that refers to the name of the town where the holotype was collected.

Figures

Figure 2. Orancistrocerus thanhnhat sp. nov., male holotype A frontal view B head, dorsal view C antenna D mesosoma, dorsal view E propodeum, posterior view F head and mesosoma, lateral view G metasoma, dorsal view. Scale bars: 1 mm.

Figure 3. Orancistrocerus thanhnhat sp. nov., male holotype A habitus, dorsolateral view B genitalia, inner aspect of paramere with volsella and digitus C aedeagus, ventral view D aedeagus, lateral view. Scale bars: 1 mm.