Anthidiellum (Pycnanthidium) cornu Tran, Engel & Nguyen, 2023

Tran, Ngat Thi, Engel, Michael S., Nguyen, Cuong Quang, Tran, Duong Dinh & Nguyen, Lien Thi Phuong, 2023, The bee genus Anthidiellum in Vietnam: descriptions of five new species and the first male of Anthidiellum coronum (Hymenoptera, Megachilidae), ZooKeys 1144, pp. 171-196 : 171

Anthidiellum (Pycnanthidium) cornu Tran, Engel & Nguyen sp. nov.

Figs 7A-G , 10C, D

Type material.

Holotype. Vietnam: ♂, Kon Tum, Sa Thay, Sa Son, Chu Mom Ray NP, 14°25'19"N, 107°43'54"E, alt. 653 m, 25.iv.2022 [25 April 2022], Lien Thi Phuong Nguyen, Ngat Thi Tran leg. [IEBR]

Paratype. Vietnam: 1♂, same data as holotype [IEBR].

Diagnosis.

The male of this species is similar to that of A. (P.) coronum . The new species differs from that species by the generally dull integument (integument shinier in A. coronum ); the form of the male gonostylus in which the mesal surface of mesal branch bears some long setae and the mesal branch is long with its lateral margins slightly convex, while the outer branch is shorter, slender, and nearly straight, and the apical margins of both branches are straight (the mesal branch is long, swollen, with lateral margins curved, the outer branch is shorter, slender, and nearly straight, and the apical margin of both branches is rounded in A. coronum ).

Description.

♂: body length 7-7.2 mm (holotype = 7.0 mm), forewing length 6.3-6.5 mm (holotype = 6.5 mm).

Structure. Head broader than long, about 1.2 × as broad as long (Fig. 7C ) Compound eyes approximately 2.1 × as long as broad, about 1.7 × genal width. Mandible tridentate, first two teeth short and equal in length, third tooth longest (Fig. 7C ). Clypeus flat, 1.8 × as broad as long. Supraclypeal area slightly convex. Antennal scape short, about 2.8 × as long as broad, pedicel approximately as broad as long and about 1.3 × length of F1, F1 broader than long and approximately 0.4 × length of F2, F2-F9, subequal in length, F10 longest flagellomere, 2.5 × as long as broad. Mesoscutum about 1.2 × as broad as long; mesoscutellum slightly convex, with mediolongitudinal depression apically (Fig. 7D ). Forewing with two submarginal cells, first submarginal cell broader than second submarginal cell. Metatibia and metabasitarsus enlarged (Fig. 7A ); metapretarsal arolium present (Fig. 7G ). Anterior surface of metasomal T1 concave; T7 with a short spine medially (Fig. 7E ); apical margin of S5 with comb of stiff, black peg-like and scale-like setae (Fig. 7F ). Male genitalia with gonostylus forked into two unequal branches, mesal surface of mesal branch with some long setae, mesal branch long, lateral margins slightly convex, outer branch shorter, slender, nearly straight, apices of both branches straight, transverse (Fig. 10C, D ).

Sculpturing and texture. Mandible with shallow, sparse punctures. Clypeus, basal half of supraclypeal area, and paraocular area from base to lower tangent of antennal toruli with shallow, dense, wrinkled punctures; remainder of supraclypeal area with coarse, dense punctures. Frons with coarse, contiguous punctures. Vertex with round, dense punctures. Mesoscutum with coarse, contiguous punctures, punctures larger than those on frons; mesoscutellum with coarse, contiguous, wrinkled punctures, punctures smaller than those on mesoscutum. Metasomal T1-T2 with small, round, dense punctures; T3-T5 with sparse punctures basally, blending to dense, wrinkled punctures on remainder of terga; T6 with shallow, dense punctures.

Color. Body dull black except as follows: mandible yellow except brownish black apically; clypeus yellow except tawny yellow on apical margin; paraocular area with yellow extending along inner ocular margin to lower tangent of antennal toruli; supraclypeal area yellow apically and laterally; antennal space apico-ventrally with small, dull yellow-orange marking; gena with yellow markings posterior to upper border of compound eye, extending from near tangent with top of eye to exceeding tangent (Fig. 7A, C ). Mesoscutellum with thin, dull yellow marking on apical margin and interrupted medially (Fig. 7B ). Profemur apically with small yellow mark; prolateral surface of protibia with thin, yellow mark; mesotibia with small yellow mark basally; superior margin of prolateral surface of metatibia with thin, yellow mark; entire metabasitarsus yellow. Metasomal T3 with yellow band interrupted medially; T4 with yellow band (interrupted medially in paratype), T5-T6 with yellow, T7 with yellowish mark medially (T7 blackish in paratype) (Fig. 7B, E ).

Pubescence. Outer surface and dorsal and apical margins of mandible with short, sparse, yellowish setae; ventral margin of mandible with short, yellowish setae intermixed with longer setae. Apical margin of clypeus with some short, yellowish setae; clypeus laterally, paraocular area, and basal half of supraclypeal area with some sparse, short, yellowish setae. Antennal scape with short yellowish setae; face above antennal torulus with tuft of long, yellowish, plumose setae. Vertex with sparse, short, yellowish setae. Mesoscutum and mesoscutellum with short, yellowish setae. Propodeum with dense, long, plumose, white setae. Prolateral surfaces of metabasitarsus and metatarsus with dense, erect, white setae; retrolateral surfaces of these same podites with tawny yellow setae. Metasomal S1 with short, white tuft of setae on apical margin; S2 with longer, white tuft of setae on apical margin; S3 with long, tawny yellow tuft of setae on medioapical margin; S4 with yellowish tuft of setae on apical margin; surface of S6 with long, yellowish setae, apical margin of S6 with long, yellowish, plumose setae.

Etymology.

The specific epithet is the Latin noun cornū (meaning, “horn” or “antler”) and refers to the shape of the gonostyli of the male genitalia, which superficially resemble antlers.

Figures

Figure 7. Anthidiellum (Pycnanthidium) cornu Tran, Engel & Nguyen, sp. nov., holotype, male A lateral habitus B dorsal habitus C facial view D mesosoma in dorsal view E oblique dorsal view of metasoma F metasomal apex, red arrow indicating stiff peg-like and scale-like setae on apical margin of metasomal S 5 G metapretarsus, red arrow indicating arolium. Scale bars: 1 mm (A, B, F); 0.5 mm (C-E, G).

Figure 10. Male genitalia of two Vietnamese species of Anthidiellum Cockerell (Anthidiini) (dorsal views at left, ventral views at right) A, B Anthidiellum (Pycnanthidium) coronum (Wu, 2004) C, D A. (P.) cornu Tran, Engel & Nguyen, sp. nov. Scale bars: 0.5 mm.