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

Fig. 6A-G

Type material.

Holotype. Vietnam: ♀, Gia Lai, Mang Yang, Ayun, Kon Ka Kinh NP, 14°13'18"N, 108°19'02"E, alt. 907 m, 26.iii.2022 [26 March 2022], Lien Thi Phuong Nguyen, Ngat Thi Tran, Cuong Quang Nguyen leg. [IEBR].

Paratypes. Vietnam: 3♀♀, same data as holotype [1♀ in IEBR; 2♀♀ in AMNH]; 2♀♀, Gia Lai, Mang Yang, Ayun, Kon Ka Kinh NP, 14°12'11"N, 108°18'58"E, alt. 834 m, 25.iii.2022 [25 March 2022], Lien Thi Phuong Nguyen, Ngat Thi Tran, Cuong Quang Nguyen leg.; 1♀, Gia Lai, Mang Yang, Ayun, Kon Ka Kinh NP, 14°12'11"N, 108°18'58"E, alt. 834 m, 26.iv.2022 [26 April 2022], Lien Thi Phuong Nguyen, Ngat Thi Tran leg.; 1♀, Gia Lai, Mang Yang, Ayun, Kon Ka Kinh NP, 14°12'11"N, 108°18'58"E, alt. 834 m, 27.iv.2022 [27 April 2022], Lien Thi Phuong Nguyen, Ngat Thi Tran leg.; 1♀, Gia Lai, Mang Yang, Ayun, Kon Ka Kinh NP, 14°12'11"N, 108°18'58"E, alt. 834 m, 28.iv.2022 [28 April 2022], Lien Thi Phuong Nguyen, Ngat Thi Tran leg. [IEBR].

Diagnosis.

The female of this species is most similar to that of A. (P.) carinatum ( Wu 1962) as both have the metatibia and metabasitarsus each with a longitudinal carina on the prolateral surface; tridentate mandibles, with the teeth sharp apically; similar yellow markings on the face; and metasomal T2 black. The new species can be distinguished in the female from the latter species by the following: mesoscutum with short anterior-facing surface at medioapical margin, with anterior surface polished and impunctate (mesoscutum nearly straight medioapically, with dense punctures just before margin in A. carinatum ); mesoscutellum black, strongly convex, with mediolongitudinal depression apically and giving apical surface a weakly bigibbous appearance (mesoscutellum nearly flat and yellow to yellowish brown on margin apicolaterally in A. carinatum ).

Description.

♀: body length 6.5-7.0 mm (holotype = 7.0 mm), forewing length 6.0-6.2 mm (holotype = 6.2 mm).

Structure. Head broader than long, about 1.2 × as broad as long (Fig. 6C ). Compound eyes about 2.1 × as long as broad and 1.4 × genal width. Mandible tridentate, teeth gradually longer, interspace between first two teeth broad, second tooth contiguous with third tooth (Fig. 6C ). Clypeus slightly convex medially, about 1.6 × as broad as long. Supraclypeal area slightly convex medially. Scape slender, about 3.2 × as long as broad, pedicel approximately 1.7 × as long as broad and about 1.6 × length of F1, F1 broader than long and approximately 1.3 × length of F2, F3-F9 gradually increasing in length, F3-F5, F6-F7, and F8-F9 subequal in length, F10 longest flagellomere, approximately 1.5 × as long as broad. Mesosoma approximately 1.2 × as broad as long; mesoscutellum strongly convex, mediolongitudinal depression in apical half, giving bigibbous appearance (Fig. 6D ). Forewing with two submarginal cells, first submarginal cell broader than second submarginal cell. Prolateral surfaces of metatibia and metabasitarsus each with a longitudinal carina (Fig. 6F ). Metapretarsus with arolium (Fig. 6G ). Metasoma faintly cordate (Fig. 6B ) owing to concave anterior surface of T1 in dorsal view (Fig. 6A, B ).

Sculpturing and texture. Clypeus and paraocular area extending from base to antennal torulus with wrinkled punctures. Supraclypeal area and frons with coarse, dense punctures. Vertex with round punctures, punctures sparser than on supraclypeal area and frons. Mesoscutum with round, contiguous punctures, except polished and impunctate on short anterior-facing surface at medioapical margin; mesoscutellum with small, round, contiguous punctures (Fig. 6D ). Metasomal T1-T3 with small, round, dense punctures; T4-T5 with small, round punctures, punctures sparser than those on T1-T3; T6 with wrinkled punctures.

Color. Body black except as follows: clypeus yellow except black on apical margin; supraclypeal area with yellow laterally bordering subantennal sulci; paraocular area with yellow marking extending along inner margin to about lower tangent of antennal toruli. Frons with small yellow drop above medially (Fig. 6C ). Gena with yellow mark above near vertex and posterior to upper margin of compound eye (Fig. 6E ). Pronotal lobe yellow except small, round, dull spot medially, mesoscutum with thin, transverse, yellow markings latero-anteriorly on anterior border; axilla yellow (Fig. 6A ). Prolateral surface of protibia yellow to yellowish brown. Metasomal T1 with yellow markings laterally, T3 basally yellow except broadly interrupted medially, T4-T5 with basal yellow bands, T6 yellow medially (Fig. 6B ).

Pubescence. Apical margin of clypeus with sparse, erect, yellow setae. Clypeus, supraclypeal area, and paraocular area with short, sparse, white to yellowish setae. Antennal scape with short, yellowish setae; above antennal toruli with long, dense, plumose tuft of diffuse white setae. Frons and vertex with short, sparse, yellowish setae. Anterior, posterior, and apical margin of mandible with short yellowish setae intermixed with some longer setae. Mesoscutum and mesoscutellum dorsally with short yellowish setae; mesoscutellum ventro-apically with longer, erect, yellow setae; propodeum with long, plumose, dense, yellowish setae. Prolateral surfaces of basitarsi and tarsi with dense, erect, yellowish setae; retrolateral surfaces of these same podites with tawny yellow setae. Metasomal T1 and T3-T5 with short, sparse, yellowish setae; T2 almost bare except some short yellowish setae laterally; T6 with short yellowish setae except dense, yellowish setae on apical margin; S2-S5 with long, dense, tawny yellow scopal setae.

♂: Latet.

Etymology.

The specific epithet is taken from the Latin adjective flāvus (meaning, “yellow”) and the noun axilla (meaning, “armpit” or “side”), and refers to the notable yellow markings on the axillae.

Figures

Figure 6. Anthidiellum (Pycnanthidium) flavaxilla Tran, Engel & Nguyen, sp. nov., holotype, female A dorsolateral oblique habitus B dorsal habitus C facial view D mesosoma in dorsal view E head and mesosoma in profile, red arrow indicating omaular carina F prolateral surfaces of metatibia and metatarsus, with red arrows indicating longitudinal carinae G metatarsus and metapretarsus, red arrow indicating metapretarsal arolium. Scale bars: 1 mm (A, B, D, E); 0.5 mm (C, F, G).