Maculonomia (Maculonomia) alveolus Engel & Tran, 2025

Tran, Ngat Thi, Phuong, Lien Thi, Anh, Phuong Nguyen, Nguyen, Anh Duc & Engel, Michael S., 2025, New species and records of the nomiine bee genus Maculonomia Wu, 1982 from Vietnam (Hymenoptera, Halictidae), Zoosystema 47 (4), pp. 51-73 : 54-59

Maculonomia (Maculonomia) alveolus Engel & Tran , n. sp.

( Figs 1-5 )

urn:lsid:zoobank.org:act:3B92492F-AF02-4477-82B8-8BEB725C6704

TYPE MATERIAL. — Holotype. Vietnam • ♂; Bac Kan, Cho Don, Binh Trai , Nam Xuan Lac NR; 22°15’19.4”N, 105°30’43.7”E; alt. 650 m; 15.VIII.2020; Truong L.X., Nguyen L.T.P., Nguyen C.Q., Tran N.T., Mai T.V., Tran U.T.P. leg.; IEBR.

Paratypes. Vietnam • 1 ♀; same data as holotype; IEBR • 2 ♀, 1♂; Bac Kan, Cho Don, Binh Trai , Nam Xuan Lac NR ; 22°16’65”N, 105°11’08”E; alt. 780 m; 12.VIII.2020; Truong L.X., Nguyen L.T.P., Nguyen C.Q., Tran N.T., Mai T.V., Tran U.T.P leg.; IEBR • 1 ♀; Bac Kan, Cho Don, Binh Trai , Nam Xuan Lac NR ; 22°16’10”N, 105°31’09”E; alt. 827 m; 13.VIII.2020; Truong L.X., Nguyen L.T.P., Nguyen C.Q., Tran N.T., Mai T.V., Tran U.T.P leg.; AMNH • 1♂; Cao Bang, Ha Lang, Duc Quang ; 22°43’12”N, 106°39’21”E; alt. 454 m; 21.IX.2023; Nguyen L.T.P., Nguyen A.D., Tran N.T. leg.; AMNH • 1 ♀; Tuyen Quang, Ham Yen, Yen Thuan , Cao Duong , Cham Chu N.R. ; 22°20’16.4”N, 103°51’09.4”E; alt. 670 m; 15.V.2019; Truong L.X., Nguyen C.Q., Mai T.V. leg.; IEBR • 2♀; Tuyen Quang, Ham Yen, Yen Thuan , Cao Duong , Cham Chu NR; 22°20’16.4”N, 103°51’09.4”E; alt. 670 m; 17.V.2019; Nguyen C.Q., Nguyen L.T.P. leg.; IEBR • 1 ♀, 1 ♂; Lang Son, Huu Lung, Huu Lien , Lan Chau , Huu Lien NR ; 21°43’22.9”N, 106°22’40.2”E; alt. 370 m; 12.VI.2018; Nguyen L.T.P., Truong L.X., Tran N.T., Luong T.V., Nguyen H.T.T. leg.; IEBR • 1♀; Hoa Binh, Mai Chau, Hang Kia-Pa Co NR ; 20°44’39”N, 104°53’30”E; alt. 1315 m; 19.V.2022; Nguyen L.T.P., Tran N.T. leg.; IEBR • 7 ♀; Hoa Binh, Kim Boi, Ha Bi , Mo Da ; 12-14.VI.2019, Nguyen C.Q. leg.; IEBR.

DIAGNOSIS. — This species is most similar to M. planiventris ( Friese, 1911) from Taiwan, as in both species the male metafemur has a lamella, parallel to the longitudinal axis of the metafemur, that spans nearly the entire length of the podite, and forms a narrow trough. Unlike M. planiventris , the apical margin of tergum I in both sexes is impunctate (punctate in M. planiventris ).

ETYMOLOGY. — The specific epithet is the Latin noun alveolus , meaning, a “small trough”, “small hollow”, or “small channel”, and refers to the small channel that is formed by the lamella that extends across the metafemur. The name is a noun in apposition.

DESCRIPTION

Male

Measurements. . Body length 11.5-12 mm (n =4; holotype = 12 mm).Forewing length 10.5-11 mm (n=4; holotype = 11 mm).

Structure. Head broader than long, approximately 1.3× as broad as long ( Fig. 2A ). Compound eyes about 1.4× genal width. Mandible simple. Clypeus broader than long, approximately 1.5× as broad as long and apical margin slightly curved. Labrum with triangular process, broader than long, approximately 2.9× as broad as long and slightly swollen basally ( Fig. 2A ). Mesosoma longer than broad, about 1.2× as long as broad; mesoscutellum with medio-longitudinal depression apically and strongly bigibbous ( Fig. 2B ). Forewing with three submarginal cells, first and third submarginal cells broader than second submarginal cell, 1m-cu entering near apex of second marginal cell ( Fig. 1B ). Metafemur swollen, ventral surface with a narrow trough extending along two-thirds length, metatibia gradually expanding toward apex and inner surface with an obvious spine at one-third length from base ( Fig. 2C ). Metasomal T2 half-basally concave ( Figs 1A ; 2D ). Metasomal S4 with deeply emarginate medioapically and bilobed, apical margin of each lobe raised medially ( Fig 3A ). S5 thin basally, apically thickened and with an equilateral triangular process medio-apically ( Fig. 3B ). S6 emarginate medioapically, apical margin as in figure 3C. S7 with apical margin broadly and deeply concave, with apicolateral lobes at margins of concavity bearing tufts of elongate setae, minute lobe mesad apicolateral lobe and also with a few long setae ( Fig. 3D ). S8 with broad spiculum and apical margin slightly concave with broad protrudent plate medially ( Fig. 3E ). Gonostylus complex, with dorsal and ventral gonostylar lobes (referred to as individual gonostyli – dorsal and ventral – by some authors but the genitalia of Hymenoptera have a single gonostylus on each side, which may then be further subdivided). Dorsal gonostylar lobe expanded, flattened, and lamelliform mesally, with long, slender, apically spatulate process bearing, ventroapical margin with smaller lamella, before tapering to short, slender process (i.e., apex bifid) ( Fig. 3F ), with elbowed mesal process proximally with thin, flattened plate apically ( Fig. 3F, G ). Ventral gonostylar lobe a thinner process with rounded apex, inner margin curved, outer margin slightly wavy ( Fig. 3G ).

Sculpturing. Clypeus medially with dense coarse punctures, punctures sparser latero-apically; supraclypeal area with dense, coarse, contiguous punctures; paraocular area with dense, contiguous punctures; scape with small, sparse, shallow punctures; frons with coarse, dense, contiguous punctures ( Fig. 2A ); vertex with dense punctures, generally puncture sizes larger and coarser than those on frons, except outer margin of ocellus with shiny, smooth, impunctate area. Mesoscutum with small, dense, round punctures; mesoscutellum with sparse punctures except latero-basally with dense round punctures ( Fig. 2B ). Metasomal T1 with dense (not contiguous), round punctures; metasomal T2 disc half-basally with small, sparse punctures and larger and denser punctures on remainder, metasomal T3-T6 with small, dense (not contiguous) punctures except relatively sparse medially; marginal zones of T1-T5 basally with small, dense (not contiguous) punctures and smooth, shiny, and impunctate on remainder ( Fig. 2D ).

Color. Body generally black except mandible ferruginous medially ( Fig. 2A ). Forewing relatively hyaline except infumate apically ( Fig. 1B ). Metasomal T2-T5 with shiny, pale yellowish-green band apically ( Figs 1 ; 2D ).

Pubescence. Clypeus, supraclypeal area, and paraocular area extending from base to lower torular tangent with yellowish, plumose setae; scape with some short, yellowish setae; face above antennal torulus with tufts of long, yellowish, plumose setae ( Fig. 2A ); frons and vertex with yellowish setae; gena with yellowish, relatively dense, plumose setae. Pronotum with short, dense, white setae intermixed with longer, yellowish, plumose setae. Pronotal lobe with blackish setae except outer margin with short, dense, whitish, plumose setae ( Fig. 1A ). Mesoscutum with short, yellowish setae intermixed with some blackish setae ( Fig. 2B ). Mesosoma laterally and ventrally with long, dense, yellowish, plumose setae ( Fig. 1A ). Propodeum laterally with tuft of yellowish, plumose setae ( Fig. 1 ). Ventral surfaces of coxae, trochanters, pro- and mesofemora with tufts of yellowish, plumose setae. Outer surfaces of protibia, probasitarsus, mesotibia, and mesobasitarsus with short, yellowish setae and inner surfaces of these podites with bristle-like ferruginous setae. Outer surfaces of metafemur, metatibia, and metabasitarsus with yellowish setae. Inner surfaces of metatibia and metabasitarsus with bristle-like, ferruginous setae. Metasomal T1 with yellowish setae, T2 with yellowish setae except some long, blackish setae apically, metasomal T3-T5 with blackish setae ( Fig. 1 ).

Female

Measurements. Total body length about 10-11 mm, forewing length 9.5-10 mm (n = 16).

Structure. Basically similar as male (vide supra) except usual sex differences (e.g. mandible with preapical tooth, metafemur not swollen, metabasitibial plate present, metabasitarsus compressed) ( Figs 4A ; 5B ).

Sculpturing. As described for male (vide supra) except punctures of clypeus and mesoscutellum denser ( Fig. 5A, B ).

Color. As described for male (vide supra) except pale yellowish-green bands on metasomal T2-T4 thinner and metasomal T5 black ( Fig. 5D ).

Pubescence. As described for male (vide supra) except outer surface of metatibia with yellowish scopa ( Fig. 4A ), metasomal S2-S5 with yellowish setae apically.

Figures

FIG. 1. — Maculonomia (Maculonomia) alveolus Engel & Tran, n. sp., holotype, male: A, lateral habitus; B, dorsal habitus. Scale bars: 1 mm.

FIG. 2. — Maculonomia (Maculonomia) alveolus Engel & Tran, n. sp., holotype, male: A, facial view; B, mesosoma in dorsal view; C, metafemur and metatibia in profile; D, metasoma in dorsal view. Scale bars: 1 mm.

FIG. 3. — Maculonomia (Maculonomia) alveolus Engel & Tran, n. sp., paratype, male: A, S4 in frontal view; B, S5 in frontal view; C, S6 in frontal view; D, S7 in frontal view; E, S8 in frontal view; F, male genitalia in dorsal view; G, male genitalia in ventral view. Scale bars: A-C, F, G, 1 mm; D, E, 0.5 mm.

FIG. 4. — Maculonomia (Maculonomia) alveolus Engel & Tran, n. sp., paratype, female: A, lateral habitus; B, dorsal habitus. Scale bars: 1 mm.

FIG. 5. — Maculonomia (Maculonomia) alveolus Engel & Tran, n. sp., paratype, male: A, facial view; B, mesosoma in dorsal view; C, metatibia showing the basal plate; D, metasoma in dorsal view. Scale bars: A, B, D, 1 mm; C, 0.5 mm.