Stenodynerus fastidiosissimus (de Saussure, 1855) PT Salema

Selis, Marco, Cilia, Giovanni, Wood, Thomas J. & Soon, Villu, 2024, Taxonomic revision of the Stenodynerus fastidiosissimus species-group in Western Europe and North Africa (Hymenoptera: Vespidae: Eumeninae), Zootaxa 5418 (1), pp. 34-56 : 52-53

Key to the species of the Stenodynerus fastidiosissimus -group

1. Clypeus as long as wide; apical margin of clypeus deeply emarginate, emargination 0.3× as deep as wide. Gena narrow, 0.55× as wide as eye at bottom of ocular sinus; occipital carina highly lamellate in upper half and delimiting a crenate furrow ( Fig. 5A ). Parategula straight and pointing out, nearly horizontal. Lateral carinae of propodeum absent, transition between dorsal and lateral faces entirely rounded. Scutellum entirely yellow. Female: apical teeth of clypeus sharply pointed and carinate, carinae reaching up to middle of clypeus; ocular sinus entirely yellow.................................. S. muelleri (Dusmet)

-. Clypeus variable. Gena wide, 0.85–1.0 (♀) or 0.75–0.85 (♂) × as wide as eye at bottom of ocular sinus; occipital carina shortly lamellate and not delimiting a furrow ( Fig. 4B ). Parategula curved and pointing behind. Lateral carinae of propodeum present, transition between dorsal and lateral faces marked by an irregular but distinct margin. Scutellum usually black or with small lateral spots, rarely with a band covering the posterior half at most. Female: apical teeth of clypeus with short blunt carinae; ocular sinus entirely black.............................................................................. 2

2. Black with ferruginous-red markings; propodeum black. Apical emargination of male clypeus 0.55× as deep as wide, lateral teeth long and narrow, acutely pointed................................................ S. rufescens Giordani Soika

-. Black with yellow markings; propodeum usually marked with yellow, often black in males. Apical emargination of male clypeus 0.15–0.35× as deep as wide, lateral teeth shorter and variable in shape..................................... 3

3. ♀: flagellum 10-segmented and apically simple, six metasomal segments......................................... 4

-. ♂: flagellum 11-segmented and apically hooked, seven metasomal segment....................................... 7

4. Apical margin of clypeus shallowly but distinctly concave. Occipital carina on gena wider and distinctly curved in the middle. Pronotal carina evenly rounded on sides, pronotal humeri obtuse in dorsal view ( Fig. 5C )............................ 5

-. Apical margin of clypeus usually subtruncate. Occipital carina on gena of same width for its entire length and almost straight. Pronotal carina produced at extreme sides, pronotal humeri sharply right-angled in dorsal view ( Fig. 5D )................ 6

5. Clypeus shorter, 0.9× as long as wide; apical teeth not carinate; apical emargination shallower, 0.2× as deep as wide. T2 with a short translucent lamella exceeding apical crenulate margin ( Fig. 5E ). Punctures finer and sparser on head, mesosoma and T1, most interspaces narrow but flattened and sparsely micropunctate, shiny; lateral face of propodeum with fine striation and dense small punctures; punctures on T2 finer and denser, interspaces on disc up to 2× puncture diameter ( Fig. 5E ). T3–T5 with wide yellow bands........................................................................ S. difficilis (Morawitz)

-. Clypeus longer, as long as wide; apical teeth carinate; apical emargination deeper, 0.25× as deep as wide. T2 without lamella exceeding apical crenulate margin ( Fig. 5F ). Punctures coarser and denser on head, mesosoma and T1, most interspaces reduced to ridges and densely micropunctate, matte; lateral face of propodeum with flat-bottomed polygonal cells forming irregular ridges and sparse small punctures; punctures on T2 coarser and sparser, interspaces on disc up to 4× puncture diameter ( Fig. 5F ). T3–T6 entirely black................................................................. S. laborans (Costa)

6. Disc of S2 sparsely punctured, punctures irregularly scattered and interspaces at least equal to puncture diameter ( Fig. 5G ). Triangular lobes of submarginal carina entirely black or with a narrow yellowish margin, about 0.3× as long as the distance between their bases ( Fig. 5I )........................................................ S. montanus Selis , sp. nov.

-. Disc of S2 densely punctured, punctures arranged in transverse series and interspaces shorter than half puncture diameter ( Fig. 5H ). Triangular lobes of submarginal carina largely yellow and with a broad translucent margin, about 0.5× as long as the distance between their bases ( Fig. 5J )............................................ S. fastidiosissimus (de Saussure)

7. Apical margin of clypeus wider than distance between toruli, and emargination 0.3× as deep as wide; punctures on clypeus dense but nearly absent on upper fourth, rounded on dorsal half and elongate in dense irregular shallow striae on ventral half. F11 longer and broader, reaching middle of F 8 in lateral view, 2.3× as long as basally wide in dorsal view; flattened dorsoventrally and elliptical in section. S2 densely punctured, most interspaces narrower than puncture diameter, especially on lateral thirds; several punctures arranged in irregular transverse series ( Fig. 5H ). Ventral lobe of aedeagus elongate, with rounded apex and a small denticle in lateral view................................................... S. fastidiosissimus (de Saussure)

-. Clypeus variable. F11 shorter and slimmer, reaching base of F 9 in lateral view, 2.8× as long as wide in dorsal view; not flattened, nearly circular in section. S2 sparsely punctured, interspaces wider than puncture diameter, except sometimes on posterior corners; punctures isolated and not forming series ( Fig. 5G ). Ventral lobe of aedeagus different, shorter and subtriangular in lateral view.......................................................................................... 8

8. Apical teeth of clypeus blunt and shorter, apical emargination 0.15–0.2× as deep as wide and with a broad translucent margin. Apical part of aedeagus wider, maximum width 2.5× as wide as basal width of median apodeme; ventral lobes right angled and pointing out, slightly diverging in ventral view; lateral apodemes sinuate in basal half but otherwise nearly straight........................................................................................ S. montanus Selis , sp. nov.

-. Apical teeth of clypeus sharp and longer, apical emargination 0.3–0.35× as deep as wide and with a short translucent margin. Apical part of aedeagus narrower, maximum width 2× as wide as basal width of median apodeme; ventral lobes straight and slightly converging basally in ventral view; lateral apodemes angled in the middle.................................. 9

9. Clypeus longer, as long as wide. T1 more coarsely and densely punctured, interspaces reduced to narrow irregular ridges ( Fig. 5K ); T3–T6 with coarser and denser punctures. Metasoma black starting from T3 and S3.............. S. laborans (Costa)

-. Clypeus shorter, about 0.9× as long as wide. T1 more finely and sparsely punctured, most interspaces equal to half puncture diameter or wider and flattened ( Fig. 5L ); T3–T6 with sparser and finer punctures. Metasoma with yellow bands on T3–T6 and sometimes on S3–S4.................................................................. S. difficilis (Morawitz)

Figures

FIGURE 4. A, Stenodynerus muelleri (Dusmet, 1917): habitus of male, habitus of female, head of male, head of female, flagellum of male, aedeagus in ventral and lateral view. B, female holotype of Stenodynerus gusenleitneri Giordani Soika, 1986: habitus in dorsal view and labels. C, Stenodynerus rufescens Giordani Soika, 1977: habitus of male, habitus of female, head of male, head of female, flagellum of male, aedeagus in ventral and lateral view.

FIGURE 5. A, Stenodynerus muelleri, gena in lateral view. B, Stenodynerus difficilis, gena in lateral view. C, Stenodynerus difficilis, pronotum in dorsal view. D, Stenodynerus fastidiosissimus, pronotum in dorsal view. E, Stenodynerus difficilis, apex of T2 in dorsal view. F, Stenodynerus laborans, apex of T2 in dorsal view. G, Stenodynerus montanus, S2 in ventral view. H, Stenodynerus fastidiosissimus, S2 in ventral view. I, Stenodynerus montanus, apex of propodeum in dorsal view. J, Stenodynerus fastidiosissimus, apex of propodeum in dorsal view. K, Stenodynerus laborans, disc of T1 in dorsal view. L, Stenodynerus difficilis, disc of T1 in dorsal view.