Maculonomia (Maculonomia) rufomysteria Engel, Tran & A.D. Nguyen

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 : 61-65

Maculonomia (Maculonomia) rufomysteria Engel, Tran & A.D. Nguyen , n. sp.

( Figs 8-10 )

urn:lsid:zoobank.org:act:5782C286-D12A-4C72-969B-430DCF01B896

TYPE MATERIAL. — Holotype. Vietnam • ♂; Lam Dong, Bidoup Nui Ba; 24.IX.2019; Pham N.T. leg.; IEBR.

ETYMOLOGY. — The specific epithet is a combination of the Latin adjectives rūfus, meaning, a “reddish”, and mystērius, meaning, “mysterious”.

DIAGNOSIS. — This species superficially resembles M. rufocaudata owing to the overall black coloration combined with abundant reddish orange setae on the apical metasomal terga, as well as the presence of enamel apical bands. Unlike M. rufocaudata , however, the reddish orange setae are restricted to terga V and VI, while in M. rufocaudata the color is extensive across terga III-V. Additionally, in the new species the orange, apical, enamel bands are complete on terga V and VI, and only present as small spots at the extreme lateral portions of tergum IV, rather than the complete bands found in M. rufocaudata on terga III-V. In M. rufocaudata the wing is uniformly yellowed to yellowish brown, often a bit lighter apically beyond the veins. In the new species the forewing is yellow, then paler just beyond the veins before forming a large, apical, infumate spot, resembling somewhat the apical spot of M. terminata . In M. rufocaudata the mesoscutellum is unmodified or with weak paramedial callosities, while in the new species there are prominent elevated tubercles on either side of the midline. Naturally, given that the male of M. rufocaudata is currently unknown it was tempting to consider this male as conspecific with the aforementioned females attributed to M. rufocaudata . We have erred on the side of splitting, however, given the rather prominent habitat differences: M. rufocaudata from mountains in the North of Vietnam and Tibet, versus the more isolated mountain of Bidoup National Park in Central Highlands Vietnam. Moreover, the pattern of wing coloration is quite divergent between the two. Additionally, the punctures of tergum II are smaller and separated by about a puncture width in M. rufocaudata versus the slightly larger punctures distinctly separated by much less than a puncture width in the male described here. Thus, pending the discovery of a male from Tibet or the mountainous populations of northern Vietnam that might indicate otherwise, we consider this Central Highlands male as distinct but obviously closely allied.

DESCRIPTION

Male

Measurements. Total body length 13.5 mm, forewing length 11.5 mm.

Structure. Head broader than long, approximately 1.2× as broad as long ( Fig. 10A ); compound eyes approximately 1.4× genal width; mandible simple; clypeus slightly convex laterally, approximately 1.3× as broad as long; supraclypeal area slightly convex ( Fig. 9A ). Mesosoma approximately 1.2× as long as broad; mesoscutellum with mediolongitudinal depression apically and strongly bigibbous ( Fig. 9B ). 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. 8A ). Metafemur slightly swollen ( Fig. 9C ); metatibia gradually expanding toward apex and inner surface with slightly raised knob at one-third length from base. Metasomal S4 with deeply, narrowly emarginate medioapically, margin relatively straight and sloping to middle on either side of emargination ( Fig. 10A ). S5 with an isosceles-triangle-shaped process medio-apically, and long thin processes on either side of midline bearing abundant setae ( Fig. 10B ). S6 apical margin emarginate medially, emargination shallow and comparatively narrow, apical margin as in Figure 10C. S 7 apical margin broadly concave with apicolateral lobes on either side of concavity bearing elongate setae, smaller lobe mesad apicolateral lobes and also with many long setae ( Fig. 10D ). S8 with broad spiculum, apical margin slightly concave with broad medial plate ( Fig. 10E ). Dorsal gonostylar lobe expanded, flattened, and lamelliform mesally, apex bifid, with ventral portion long, thin and mesally directed, ventral apical margin with smaller lamella, then narrowed toward apex and round apically with many long setae ( Fig. 10F ), with elbowed mesal process proximally with thin, flattened plate apically ( Fig. 10F, G ). Ventral gonostylar process narrow with rounded apex, inner margin curved, outer margin strongly wavy ( Fig. 10G ).

Sculpturing. Clypeus with dense punctures on basal half, sparser, and somewhat wrinkled punctures on remainder; punctures on supraclypeal area denser than those on clypeus; paraocular area with dense punctures on basal half and sparser punctures on remainder; scape with small, sparse punctures ( Fig. 9A ); frons with dense, nearly contiguous punctures; vertex with shiny, shallow punctures, punctures sparser than those on frons, except outer margin of median ocellus with shiny, smooth, impunctate area. Mesoscutum and mesoscutellum with dense (not contiguous) round punctures ( Fig. 9B ). Disc of metasomal T1 with round punctures separated by about a puncture width, apical marginal zone broad, with small, dense punctures basally but otherwise impunctate; punctures on discs of T2-T6 smaller and denser than those of T1, with apical margin zones impunctate except small, dense punctures in basal quarters to thirds ( Fig. 9D ).

Color. Body black except forewing yellow, then paler just beyond veins before forming a large, apical, darkly infumate spot ( Fig. 8A ). Metasomal T5-T6 with shiny, orange bands apically ( Figs 8 ; 9D, E ).

Pubescence. Clypeus and supraclypeal area with some blackish, plumose setae; paraocular area from base to lower torular tangent with long, dense, blackish, plumose setae; scape with some blackish setae; face above antennal torulus with tufts of long, yellowish-black to blackish, plumose setae ( Fig. 9A ). Mesoscutum covered with dense, soft, blackish, plumose setae; setae of mesoscutellum longer than those on mesoscutum ( Fig. 9B ). Propodeum with tuft of blackish, plumose setae laterally. Ventral surfaces of coxae, trochanters, pro- and mesofemora with tufts of soft, blackish, plumose setae. Outer surfaces of tibiae and basitarsi with bristle-like and blackish setae, inner surfaces of metatibia and metabasitarsus with bristle-like and ferruginous setae. Metasomal T1-T4 covered with dense, soft, blackish setae; T5-T6 with reddish-orange setae.

Female

Unknown.

NON-COLORED-BANDS GROUP ( APICALIS GROUP)

Figures

FIG. 8. — Maculonomia (Maculonomia) rufomysteria Engel, Tran, & A.D. Nguyen, n. sp., holotype male: A, lateral habitus; B, dorsal habitus. Scale bars: 1 mm.

FIG. 9. — Maculonomia (Maculonomia) rufomysteria Engel, Tran, & AD Nguyen, n. sp., holotype male: A, facial view; B, mesosoma in dorsal view; C, metatibia showing the basal plate; D, metasoma in dorsal view; E, metasomal T5-T7 in dorsal view. Scale bars: 1 mm.

FIG. 10. — Maculonomia (Maculonomia) rufomysteria Engel, Tran, & AD Nguyen, n. sp., holotype 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. 7. — Maculonomia (Maculonomia) rufocaudata (Wu, 1988), female from Lao Cai province: A, facial view; B, mesosoma in dorsal view; C, metatibia showing the basal plate; D, metasoma in dorsal view. Scale bars: 1 mm.