Anterhynchium ( Dirhynchium ) conformalum Dang, Tran, AD Nguyen & Nguyen, 2025

Anterhynchium ( Dirhynchium) conformalum Dang, Tran, AD Nguyen & Nguyen , sp. nov.

( Figs 4–6 View FIGURE 4 View FIGURE 5 View FIGURE 6 , 7D View FIGURE 7 )

Anterhynchium ( Dirhynchium) flavomarginatum flavomarginatum View in CoL : Nguyen 2015: 137 View Cited Treatment , misidentification.

Diagnosis. This species can be distinguished from other congeners by the following characteristics: clypeus longer than wide (about 1.3 × as high as wide in male and 1.1 × as high as wide in female); inner eye margins in male strongly convergent ventrally, in frontal view about 1.4 × further apart from each other at vertex than at clypeus, in female about 0.9 × further apart from each other at vertex than at clypeus; male clypeus in frontal view about 1.3 × high as wide, with apical margin deeply emarginate medially, forming blunt tooth on each lateral side, width of emargination slightly greater 1/3 width of clypeus between inner eye margins; female clypeus in frontal view about 1.1 × as high as wide, apical margin shallowly emarginate medially, forming a blunt triagle tooth on each lateral side, width of emargination about 1/4 width of clypeus between inner eye margins; male genitalia with digitus almost knife shape apically, with swollen round apex, with dense and long setae on its surface, about 2.9 × as long as wide (at widest part); penis valve long, about 1.4× as long as basal apodeme, in profile apical part strongly produced into a small triangle lobe, middle rod shorter than basal apodeme; body black except large yellow mark on clypeus in male, small spot between antennal socket and anteral scape beneath, and in female tergum I or sometimes tergum II laterally with a narrow yellow band at apical margin.

Description. MALE ( Fig. 5B View FIGURE 5 , holotype habitus) (measurements of holotype are given in parentheses). Body length 12.0–13.0 mm ( 12.5 mm); fore wing length 11.0–12.0 mm ( 11.5 mm).

Head in frontal view subcircular, slightly less than 1.1 × as wide as high ( Fig. 4A View FIGURE 4 ). Vertex without cephalic foveae. Distance from posterior ocelli to apical margin of vertex about 3.4 × distance from posterior ocelli to inner eye margin ( Fig. 4B View FIGURE 4 ). Gena much narrower than eye, in lateral view about 0.4 × as wide as eye (at end of ocular sinus) ( Fig. 4D View FIGURE 4 ). Occipital carina complete, present along entire length of gena. Inner eye margins strongly convergent ventrally; in frontal view about 1.4 × further apart from each other at vertex than at clypeus. Clypeus in lateral view weakly convex at basal half, then straight to apical margin, in frontal view about 1.3 × high as wide, with basal margin almost straight, distinctly separated from antennal sockets, distance from basal margin of clypeus to antennal socket about half of socket diameter; apical margin deeply emarginate medially, forming blunt tooth on each lateral side ( Fig. 4A View FIGURE 4 ), width of emargination slightly greater 1/3 width of clypeus between inner eye margins. Mandible with prominent teeth, fifth tooth long and pointed apically. Antennal scape about 3.5 × as long as its maximum width; flagellomere I slightly more than 2 × longer than wide, flagellomeres II–VII slightly longer than wide, flagellomeres VIII–IX slightly wider than long, flagellomere X small, terminal flagellomere long and narrow, extends backward to reach near middle of flagellomere VII ( Fig. 4C View FIGURE 4 ).

Mesosoma longer than wide in dorsal view. Pronotal carina slightly raised, produced as humeral angles, reaching ventral corner of pronotum. Mesoscutum convex, shorter than wide between tegulae, about 0.93 × shorter than wide ( Fig. 4E View FIGURE 4 ); anterior margin broadly rounded. Disc of scutellum slightly convex. Metanotum angle. Propodeum excavated medially, surrounded laterally by sharp borders, basal triangular area with basal fovea, at lower end of area median furrow runs to apical margin, lower part of propodeum produced ( Fig. 4F View FIGURE 4 ); dorsal surface smoothly connected to posterior surface.

Tergum I narrower than tergum II, round at base ( Fig. 5A View FIGURE 5 ); anterior vertical surface of tergum I weakly convex, with some shallow punctures. Tergum I in dorsal view about 1.5 × as wide as long, tergum II in dorsal view about 1.4 × as wide as long ( Fig. 5A View FIGURE 5 ); sternum II gradually convex from base to apical margin.

Body covered with short, silver setae except temple and lower part of propodeum with longer setae. Clypeus with shallow ill-defined coarse punctures at center, punctures at sides smaller. Mandible with several shallow small punctures. Frons densely covered with flat bottom large and dense punctures. Vertex and gena with deep and welldefined punctures, interspaces between punctures smooth, area on vertex behind ocelli with large smooth area ( Fig. 4B View FIGURE 4 ). Pronotum with coarse punctures, spaces between punctures narrow, strongly raised to form reticulation. Mesocutum densely and coarsely covered with flatbottomed punctures, puncture near lateral margin with interspaces raised to form reticulation. Punctures on scutellum similar to those near lateral margin of mesoscutum. Punctures on metanotum very coarse and large.Mesepisternum with bigger and coarser punctures posterodorsally than in pronotum, barely punctured anteroventrally; border between posterodorsal and anteroventral parts distinct. Metapleuron with strong short striae at lateral of dorsal area, with sparse shallow punctures and very week short striae in ventral area. Propodeum with punctures on dorsal surface very coarse and large, with interspaces between punctures strongly raised to form reticulation, punctures on lateral parts much shallower than in dorsal part, posterior surface shiny, with oblique long and strong striae carinae on almost all surface, upper part of inferior ridges irregularly spinose ( Fig. 4F View FIGURE 4 ). Tergum I covered with dense and deep punctures, with interspace smaller than puncture diameter, punctures near apical margin of tergum I much deeper, larger and coarser than those on other part of tergum, punctures on tergum II smaller and sparser than punctures on tergum I, punctures near apical margin larger and coarser than those on other part of tergum, punctures on terga III–V much smaller and weaker than those on terga I–II, punctures near apical margin of terga III–V also deeper, larger and coarser than those on other parts of terga; tergum VI with minute punctures; punctures on sternum II uniform and slightly deeper and larger than those on tergum II, narrow basal part of sternite I smooth.

Color. Black, the following part yellow: a large mark on clypeus, small spot between antennal socket and anteral scape beneath, apex of all tibia reddish brown. Propodeal valvulae dark brown. Wings dark brown, slightly infuscate, veins dark brown.

Genitalia ( Fig. 6 View FIGURE 6 ) were taken from specimens from Ha Giang, Lao Cai, Yen Bai, Ninh Binh, Thanh Hoa (in the northern part), and Dong Nai (in the southern part) Provinces. Tergum VIII widest near base, with lateral margins almost parallel at half-base, about 2.2 × as long as wide (at widest part), with narrow part at apex long (about 0.3 × its length) ( Fig. 6A View FIGURE 6 ). Parameral spine without setae. Volsella flattened, spatulate, wide on inner aspect, and without setae at top ( Fig. 6B View FIGURE 6 ). Digitus almost knife shape apically, with swollen round apex, with dense and long setae on its surface, left margin strongly concaves from base to near apex and right margin gradually convex from base to apex, about 2.9 × as long as wide (at widest part) ( Fig. 6C View FIGURE 6 ). Penis valve long ( Figs 6D, E View FIGURE 6 ), about 1.4× as long as basal apodeme, in profile apical part strongly produced into a small triangle lobe ( Fig. 6E View FIGURE 6 ); middle rod shorter than basal apodeme.

FEMALE. ( Figs 5C, D View FIGURE 5 ) Body length 13.0–15.0 mm; fore wing length 12.4–14.4 mm. Structure as in male, but differing as follows. Head in frontal view about 1.1 × as wide as high ( Fig. 5C View FIGURE 5 ). Vertex with cephalic foveae small, bearing dense pubescence, situated close to each other with distance between foveae about half distance between posterior ocelli; depression for cephalic foveae conspicuous. Distance from posterior ocelli to apical margin of vertex about 3.0 × distance from posterior ocelli to inner eye margin. Inner eye margins weakly convergent ventrally; in frontal view about 0.9 × further apart from each other at vertex than at clypeus ( Fig. 5C View FIGURE 5 ). Clypeus in frontal view about 1.1 × as high as wide, apical margin shallowly emarginate medially, forming a blunt triagle tooth on each lateral side ( Fig. 5C View FIGURE 5 ), width of emargination about 1/4 width of clypeus between inner eye margins. Mandibular with five distinct teeth on inner side, basal tooth thick, shallowly excavated at inner margin, other tooth large, fifth tooth point apically. Antennal scape about 4.3 × as long as its maximum width; flagellomere I about 2.3 × as long as its maximum width, flagellomeres II–III longer than wide, flagellomeres IV–IX wider than long, terminal flagellomere bullet shape, as long as wide.

Color. Black, with following exceptions: spot on frons just above antennal sockets yellow; antennal scape beneath dark brown. In some specimens, tergum I or sometimes tergum II laterally with a narrow yellow band at apical margin.

Material examined. HOLOTYPE, ♂, pinned, VIETNAM, Yen Bai: Mu Cang Chai, road to Che Tao village , 12.IX.2017, L.T.P. Nguyen & C.Q. Nguyen (deposited in IB).

PARATYPES (all deposited in IB). VIETNAM. Yen Bai: 1 ♀ , same data as holotype ; Ha Giang: 1 ♂ , Tung Ba, Vi Xuyen , 3.VII.2013, V.T. Nguyen; 1 ♂ , Bac Me, Lung Cang , 22°43’47.2”N 105°12’24.3”E, 207 m, 24.VII.2019, C.Q. Nguyen, H.T. Dang & T.V. Mai (specimens with male genitalia dissected) GoogleMaps ; Cao Bang: 1 ♀ , Ha Quang, Truong Ha , 22°56’51.3”N, 106°2’21.7”E, 263 m, 13& 14.vii.2025, L.T.P. Nguyen, H.T. Dang, C.V. Duong & A.D. Nguyen; [ 2 ♀ 2 ♂, Tra Linh, Thang Hen Lake, 22°45’47.5”N, 106°17’35.7”E, 619 m, 20.V.2023; 1 ♀, Ha Lang, Thanh Nhat, 22°42’8”N, 106°39’49”E, 332 m, 18.V.2023], L.T.P Nguyen, N.T. Tran & C.Q. Nguyen GoogleMaps ; Lao Cai: 1 ♂ , Nam Cuong , 19.VIII.2006, L.T.P. Nguyen, F. Saito & J. Kojima (specimens with male genitalia dissected) ; Tuyen Quang: Ham Yen, Phu Luu, Nam Nuong , Cham Chu NP, [ 1 ♂, 22°12’36”N 105°03’22”E, 74 m, 28.X.2018; 1 ♀, 22°12’37”N 105°03’21”E, 135 m, 25.X.2018], L.T.P. Nguyen, C.Q. Nguyen, T.V. Luong GoogleMaps ; Hoa Binh: 1 ♂ , Mai Chau, Hang Kia—Pa Co National Reserve , 20°44’37.4”N 104°53’38.5”E, 1300 m, 15.VI.2025, L.T.P. Nguyen and T.T. Vu GoogleMaps ; Nam Dinh: 9 ♂ 10 ♀ ; Nghia Hung, Nghia Phong ; 20°4.9′N, 106°11.8′E; alt. 1m; VI–VIII & X.2014; Trap nests GoogleMaps ; Dang Thi Hoa; Ninh Binh: 1 ♂ , Nho Quan, Cuc Phuong NP, 20°21’06”N 105°35’23”E, 482 m, 07.VIII.2019, L.T.P Nguyen & C.Q. Nguyen (specimens with male genitalia dissected) GoogleMaps ; Thanh Hoa: 1 ♂ , Quan Hoa, Pu Hu NR, 20°29’13.3”N 104°57’47.2”E, 408 m, 13.VI.2016, L.X. Truong, D.D. Nguyen, N.T Tran & L.N. Ha (specimens with male genitalia dissected) GoogleMaps ; Dak Lak: 1 ♂ , Buon Don , Yok Don NP station, 12°52’19.1”N 107°48’25.9”E, 191 m, L.T.P. Nguyen (specimens with male genitalia dissected) GoogleMaps ; Dong Nai: 1 ♂ , Nam Cat Tien NP, Tan Phu , 10.VIII.2005, L.T.P. Nguyen & J. Kojima .

Other material examined (all deposited in IB). VIETNAM. Lao Cai: 3 ♀, Van Ban, Nam Xe, Hoang Lien- Van Ban NP, 22°2’8.7”N 103°58’16”E, 680 m, 25.VI.2021, L.T.P. Nguyen, C.Q. Nguyen & N.T. Tran; Lao Cai: 3 ♀, Ban Xeo, Bat Xat, 23.VI.2008, L.T.P. Nguyen & P.H. Pham; 1 ♂, Nam Cuong, 19.VIII.2006, L.T.P. Nguyen, F. Saito & J. Kojima; Yen Bai: 2 ♀ 1 ♂, Van Yen, Na Hau, Thon 5, 500 m, 9.IX.2017, L.T.P. Nguyen, L.X. Truong & T.T.T. Vu; 1 ♀, Tan Phuong, Khe Bin, 21°15’51.3”N, 104°38’07”E, 500 m, 7.IX.2017, L.T.P. Nguyen, C.Q.Nguyen & T.T.T. Vu; Tuyen Quang: Ham Yen, Phu Luu, Nam Nuong, Cham Chu NP, [ 1 ♀ 1 ♂, 22°12’37”N 105°03’21”E, 135 m, 27.X.2018; 2 ♀, 22°12’39”N 105°03’06”E, 74 m, 27–28.X.2018] L.T.P. Nguyen, C.Q. Nguyen & T.V. Luong; 2 ♂, Ham Yen, Phu Luu, Khieng village, Cham Chu NP, 22°10’20”N 105°03’25”E, 74 m, 27.X.2018, L.T.P. Nguyen, C.Q. Nguyen & T.V. Luong; 1 ♀, Na Hang NR; 10.VI.2017; MT; L.D. Long; 1 ♀ Tuyen Quang city, Trang Da, 21°55’48”N 105°14’23”E, 01.XII.2014, L.X. Truong, L.T.P. Nguyen, M. P. Nguyen, D.D Nguyen; Na Hang, Na Hang NR, Son Phu RS, [ 1 ♀, 22°21’07”N 105°25’34.7”E, 264m, 09.VI.2015; 1 ♂, 22°20’52.6”N 105°25’49”E, 121m, 10.VI.2015], L.T.P. Nguyen, D.D. Nguyen & L.X. Truong; Bac Kan: Cho Don, Binh Trai, Nam Xuan Lac NP, [ 1 ♂, 22°15’19.4”N, 105°30’43.7”E, 650 m, 15.VIII.2020; 2♀, 22°16’65”N, 105°30’43.7”E, 780 m, 12.VIII.2020], L.X. Truong, L.T.P Nguyen, C.Q. Nguyen, N.T. Tran, T.V. Mai & U.T.P. Tran; 1 ♀, Ba Be, 04.VII.2014, ISD-c; Lang Son: 1 ♀, Huu Lung, Huu Lien NR, Ba Leng, 21°40’45”N, 106°23’15”E, 151 m, 21.VII.2022, N.T. Tran; Huu Lung, Cai Kinh, [ 1 ♂, 21°43’36.2”N, 106°11’57.7”E, 129 m, 10.VI.2018, L.T.P Nguyen, L.X. Truong, N.T. Tran, T.V. Luong & NTTH; 1 ♂, 22°39’42.9”N, 106°15’36”E, 7 m, 24.IX.2015, L.T.P Nguyen, D.D. Nguyen & N.T. Tran]; Thai Nguyen: 15 ♂ 5 ♀; Phu Luong, Yen Lac; 21°47′N, 105°45.5′E’, alt. 73m; VII–X.2014; Trap nests; Dang Thi Hoa; Son La: 1 ♀, Nam Pam, Muong La, 660 m, 25.VII.2009, L.T.P. Nguyen, P.H. Pham & J. Kojima; 1 ♀, Copia NR, Thuan Chau, 400 m, 5.VI.2009, P.H. Pham; 1 ♀, Yen Chau, Muong Lum, 21°1’3.9”N 104°29’59.5”E, 798 m, 19.VI.2015, D.D. Nguyen; Vinh Phuc: Ngoc Thanh, Me Linh [ 1 ♀, 22.VIII.2000; 1 ♀, 11.V.2000; 1 ♂, 24.V.2000], L.T.P. Nguyen; Tam Dao NP [ 1 ♀, 19.IX.2013, T.V. Tran; 1 ♀, 20.IX.2011, D.D. Tran; 1 ♀, 900 m, 19.VIII.2005, L.T.P. Nguyen & J. Kojima; 1 ♂, 1000 m, 8.IX.2000, L.T.P. Nguyen]; Me Linh, Ngoc Thanh; 21°23′N, 105°42′E; alt. 50m [ 10 ♂ 2 ♀; VII–X.2013; 8 ♂ 5 ♀; V, VII–XI.2014]; Trap nests; Dang Thi Hoa; Tam Dao Town; 21°26.5′N, 105°37′E; alt. 400m, 5 ♂ 14 ♀; VIII-X.2014; Trap nests; Dang Thi Hoa; Ha Noi: Chuong My, Tran Phu, 20°48’44.2”N, 105°37’58.5”E, 33 m, [ 2 ♂, 6–15.V.2018; 1 ♂, 26.VI–5.VII.2018; 1 ♀, 25.IV.2029], MT, T.V. Lai; 1 ♂, Ba Vi, Ba Trai, Lam Nghiep, 9.VII.2017, L.T.P. Nguyen & T.V. Luong; 1 ♀, Khat Thuong, Ba Vi, 100 m, 16.VIII.2006, ISD-c; 1 ♂, Ba Vi NP, 10.VII.2016, P.H. Pham; Red River Delta; 21°03′N, 105°51′E; alt. 10m [ 7 ♂ 2 ♀; IV, VI, IX.2013; 20 ♂ 16♀; VIII–XI.2014]; Trap nests; Dang Thi Hoa; Hoa Binh: 1 ♀, Kim Boi, Ha Bi, Mo Da, 12–14.VI.2019, C.Q. Nguyen; 3 ♀, Da Phuc, Yen Thuy, 5, 15, 27.VII.2000, L.X. Truong; 1 ♀, Lac Thuy, Thanh Nong, 5.VIII.2017, P.H. Pham; Ninh Binh: 1 ♂, Cuc Phuong NP, Bong, 20°21’5.4”N 105°35’30.2”E, 340 m, 21.IV.2023, L.T.P. Nguyen & A.D. Nguyen; Nho Quan, Cuc Phuong NP: 1 ♂, Vuon thuc vat, 8.VIII.2019; 1 ♂, Bong khu B, 6.VIII. 2019, 356m; 1 ♂, 20°21’06”N, 105°35’23”E, 482 m, 7.VIII.2019, L.T.P. Nguyen & C.Q. Nguyen; Thanh Hoa: 3 ♂, Xuan Lien NP, Hon Can, Thuong Xuan, Van Xuan, 19°52’27.5”N 105°14’20.8”E, 106 m, 24.VIII.2012, L.T.P. Nguyen; 1 ♂, Pu Hu NR, Quan Hoa, 20°33’37.3”N 105°00’37.9”E, 15.VI.2016, D.D. Nguyen, N.T. Tran & L.N. Ha; Ha Tinh: 1 ♀, Huong Son, Son Kim, 6.V.2004, L.X. Truong; Gia Lai: 1 ♀, Kbang, Son Lang, Kon Chu Rang NR, 14°24’0.2”N, 108°32’40.2”E, 1148m, Nest#VN-TN-2018-Pp-07, 5.V.2018, L.T.P Nguyen, L.X. Truong & T.V. Luong; 1 ♂, Kon Ka Kinh NP, Dak Jo Ta, Mang Yang, 800–850 m, 1.III.2012, ISD-c; Kon Tum: 1 ♀, Dak Uy, Dak Mar, Dak Ha, 14°33’04”N 107°55’0.8”E, 630 m, 19.VII.2012, L.T.P. Nguyen.

Distribution. Vietnam (Northern, Tay Nguyen Highland, and Southern).

Etymology. The specific name refers to the similarity of the species compared to A. flavomarginatum .

Remarks. This species was recorded widely in Vietnam, from Ha Giang Province in the North to Dong Nai Province in the South under the name A. ( Dirhynchium) flavomarginatum fravomarginatum ( Smith, 1852) ( Nguyen 2015) . Carefully examination of male genitalia of this species and comparing them with those of A. ( Dirhynchium) flavomarginatum fravomarginatum ( Smith, 1852) , presented by van der Vecht (1963) and Kumar (2013), confirms that this is a new species.

This species is very similar to Anterhynchium ( Dirhynchium) flavomarginatum in general structure such as head, mesosoma, and metasoma but can be distinguished by the following combination of characters: terga I–II usually entirely black, sometimes with a narrow yellow band at apical margin laterally vs terga I–II with thick yellow apical bands in A. flavomarginatum ; male digitus with swollen round apex vs male digitus with tapered apex in A. flavomarginatum (van der Vecht 1963: fig. 6b; Kumar et al. 2013: fig. 8).