Key to species of the Scrapter carysomus group

Females

Females of this species group are very similar to each other and identification can be difficult without reference material or associated males due to sometimes very subtle differences in the surface sculpture.

1. Fore tibia on inner face medially, on outer face apically, and fore femur on outer face apically with dull yellow spot of varying size ........................................................................... S. oxalicus sp. nov.

– Foreleg blackish-brown, sometimes femur apically slightly dark yellowish-brown ........................ 2

2. Propodeum dorsolaterally (lateral to the matt propodeal triangle) partly smooth and shiny (Figs 23A– B); disc of T2 relatively coarsely and densely punctate (i=0.5–2 d) (Fig. 24A–B) ......................... 3

– Propodeum dorsolaterally (lateral to matt propodeal triangle) very finely shagreened and matt (e.g., Fig. 23C–D); disc of T2 finely, more dispersed punctate (i> 2d) or without punctation (e.g., Fig. 24C–D) ...................................................................................................................................... 4

3. Clypeus, vertex and dorsal side of mesosoma with white to light brown hair, at most few single black hairs intermixed; basal area of propodeum without rugae (Fig. 23A); T2 distinctly and densely (i=0.5–1d) punctate (Fig. 24A) ..................................................................... S. oxaliphilus sp. nov.

– Clypeus, vertex and dorsal side of mesosoma with abundant dark brown to blackish hairs intermixed with lighter hair; basal area of propodeum on anterior half with fine longitudinal rugae (Fig. 23B); T2 comparatively more shallowly and sparsely (i=2 d) punctate (Fig. 24B) ..................................... ......................................................................................................................... S. oxalissimus sp. nov.

4. Apical tergal depressions relatively broad, yellowish translucent with the adjacent apical area of the disc crescent-shaped dark reddish (Fig. 24C) .......................................... S. carysomus Davies, 2005

– Apical tergal depressions narrower and brownish translucent without reddish discoloration of the adjacent apical area of the disc (Fig. 24E–F), if apical tergal depressions yellowish translucent, then only very narrowly (Fig. 24D) .......................................................................................................... 5

5. Scutellum slightly smaller (shorter and narrower), more convex and shinier (Fig. 23E); hair on posterior surface of propodeum shorter than length of basal area of propodeum (Fig. 23E) ............. .................................................................................................................................. S. oxalis sp. nov.

– Scutellum slightly larger (longer and broader), flatter and duller (Fig. 23D–F); hair on posterior surface of propodeum longer than length of basal area of propodeum (Fig. 23D–F) ...................... 6

Separation of the following two species is very difficult:

6. Apical tergal depressions slightly broader (Fig. 24D); basal area of propodeum with slightly sparser and coarser reticulation (Fig. 23D) ..................................................................... S. oxalensis sp. nov.

– Apical tergal depressions slightly narrower (Fig. 24F); basal area of propodeum with slightly denser and finer reticulation (Fig. 23F) ......................................................................... S. oxaloides sp. nov.

Males

The male of S. oxaloides sp. nov. is unknown.

1. Foreleg with medio- and distitarsi completely bright yellow, basitarsus and tibia predominantly yellow ............................................................................................................................................... 2

– Foreleg completely dark brown to blackish, sometimes to small extent distitarsus and apical parts of mediotarsi orange-brown .................................................................................................................. 3

2. Tarsi of mid and hind leg completely bright yellow; hind tibia apically on inner side with hairs longer (Fig. 25A); genitalia as in Fig. 26A .......................................................... S. oxalicus sp. nov.

– Tarsi of mid and hind leg predominantly dark yellowish-brown to blackish; hind tibia apically on inner side with hairs shorter (Fig. 25B); genitalia as in Fig. 26B ............ S. carysomus Davies, 2005

3. Hind tibia apicomedially strongly swollen (Figs 9A, 18A); propodeum densely covered with thick, plumose hair of ± equal length (Figs 27A–B, 28A, C) ..................................................................... 4

– Hind tibia apicomedially not conspicuously swollen (Fig. 25E–F); propodeum sparsely covered with thin hair of variable length (Fig. 27C–D) ................................................................................. 5

4. S3–S5 with dense apical hair fringes (Fig. 28D); hind tibia apicomedially more strongly swollen, hairs on inner side in apical half comparatively short (Fig. 25D); genitalia as in Fig. 26C ............... .................................................................................................................................. S. oxalis sp. nov.

– S3–S5 with sparse apical hair fringes (Fig. 28B); hind tibia apicomedially less swollen, hairs on inner side in apical half comparatively long (Fig. 25C); genitalia as in Fig. 26D ....... S. oxalensis sp. nov.

5. Clypeus medially finely and sparsely punctate, shiny; basal area of propodeum without or anteriorly only with very short, indistinct longitudinal carinae (Fig. 27C); genitalia as in Fig. 26E ................. ......................................................................................................................... S. oxaliphilus sp. nov.

– Clypeus medially coarsely and denser punctate, matt; basal area of propodeum with distinct longitudinal carinae that extend over the majority of the length of the segment (Fig. 27D); genitalia as in Fig. 26F .................................................................................................. S. oxalissimus sp. nov.