Mythenteles evenhuisi, Perkovsky & Sun & Perkovsky & Pape, 2025

Mythenteles evenhuisi sp. nov.

( Figs 1 View FIGURE 1 , 2 View FIGURE 2 , 3D–F View FIGURE 3 )

Diagnosis. V ein R 2+3 joining R 1 much before midpoint; r-m vein positioned in the middle of dm cell, perpendicular to M 4 attachment in relation to longitudinal axis of the wing ( Fig. 2E–F View FIGURE 2 ); male terminalia has a long, ventromedian process, externally viewed ( Fig. 1C–F View FIGURE 1 ).

Type material. Holotype ♂ SIZK UA-27921 [ Rovno amber; holotype indicated by arrow engraved on the surface] . Paratypes: 13 ♂♂ from one piece of amber, distributed in four samples: 1 ♂, UA-27919 ; 2 ♂♂, UA-27920 ; 8 ♂♂, UA-27921 (a ninth male is the holotype) ; 2 ♂♂, UA-27922 .

Etymology. Named in recognition of Neal L. Evenhuis of the Bishop Museum for his many major contributions to dipterology.

Description. Holotype ♂ ( Fig. 1B View FIGURE 1 ). Length: 1.75 mm (from antennal insertion to posterior part of epandrium).

Head. Black; occiput and vertex black; eyes dichoptic separated at vertex by distance between lateral ocelli; antennae black; scape minute; pedicel cylindrical, slightly wider than long; first flagellomere ovoid, length slightly less than twice the greatest width; second flagellomere about 0.6 × as long as first, with apical style; proboscis brown, short; palpus not evident.

Thorax. Scutum with a pair of yellow admedian vittae from humeral calli to prescutellar area ( Fig. 1B View FIGURE 1 ); lateral sclerites, prescutellar area and scutellum yellow; legs dark brown.

Wing ( Fig. 1B View FIGURE 1 ; 2E, F View FIGURE 2 ). Hyaline; Costa ends just beyond vein R 4+5; vein Sc incomplete, ending about where R 2+3 joins R 1; R 2+3 joins R 1 much before midpoint; R 2+3 arising almost perpendicularly from Rs; R 4+5 with a slight curve; vein M 1 slightly curved toward wing margin; M 2 fairly straight to wing margin except for slight curve in distal fifth; crossvein dm-cu closing discal cell present; line through cell dm from attachment of r-m to attachment of M 4 almost perpendicular to longitudinal axis of wing; vein A 1 present as a curved fold; sparse fringe of rather long setulae along posterior margin of wing.

Abdomen. Dorsum brown or black, with a yellow fascia on posterior margin of each tergite; venter brown or yellow. Parameral sheath long, apically bifid; a straight, strongly sclerotized, parallel-sided rod (fused gonocoxae?) almost half as long as the abdomen projects ventromedially ( Fig. 1C–F View FIGURE 1 ).

Remarks. Mythenteles evenhuisi differs from all other species of Mythenteles by vein R 2+3 joining R 1 much before midpoint; and by a unique shape of wing cell dm, where a line drawn from the attachment of r-m to the attachment of M 4 is almost perpendicular to the longitudinal axis of the wing (this line is clearly slanting in other species of Mythenteles , with anterior part more proximal than posterior part, see Evenhuis 2003). Additionally, the male terminalia of M. evenhuisi feature a long, ventromedian process, here tentatively interpreted as elongated and fused gonocoxites, not observed in any other species of the genus. Mythenteles evenhuisi has the second flagellomere about 0.6 × as long as first, R 2+3 arising almost perpendicularly from Rs, and the abdomen with a yellow fascia on the posterior margin of each tergite; while M. baltica has the second flagellomere about 1/3 as long as the first, vein

R 2+3 arising at an acute angle from Rs, and the abdominal terga all shining brown ( Evenhuis 2002).

Mythenteles evenhuisi is similar to M. baltica by both having a pair of yellow admedian vittae, but in M. evenhuisi the vittae reach the entire length of the scutum to fully separate the black marking into a dorsomedian part and a pair of lateral parts (some variation is apparent, and some specimens have the anterior part of vittae very narrow). The bifid parameral tip is shared with M. baltica .

The length of M. evenhuisi is 1.6–2.0 mm vs. 0.98–1.06 mm indicated for M. baltica ( Evenhuis 2002) , but this is partly an artefact from difficulties in measuring, and the two species are probably about the same size (Evenhuis pers. comm. 2023).