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Key to Myrmica of European ambers
Key to identifications of fossil Myrmica species from late Eocene European ambers (workers) (modified from Radchenko, 2023).
1
- Propodeum with short, blunt teeth; head and mesosoma with not coarse reticulation; frontal carinae merge with rugae, which surround antennal sockets; antennal funiculus with 3-segmented club (Fig. 1, A, B). Meso- and metatibiae with pectinate spurs => Myrmica paradoxa
- Propodeum with long spines; head and mesosoma with much coarser rugosity and/or reticulation (Figs 1, C, D; 2, A, B, D-H; 3, A, C, D; 4, A, C-F). Frontal carinae merge with rugae that extend to posterior third of head dorsum, they do not curve outwards and do not merge with rugae that surround antennal sockets (Figs 2, F; 3, A; 4, E). Antennal funiculus with 4-segmented club (Figs. 1, C, D; 2, A, B, D, E, H, I; 3, A, D; 4, A, C). Meso- and metatibiae with or without spurs => 2
Radchenko (2023), Figure 1. Myrmica paradoxa, workers: (A) holotype and paratype, general view (arrows indicate propodeal teeth); (B) holotype, head and antenna (arrows indicate shape of frontal carina and 3-segmented funicular club); Myrmica longispinosa, worker, neotype: (C) body, right side lateral view; (D) body, left side dorso-lateral view; (E) hind tibia. Scale bars: A–D – 1 mm, E – 0.5 mm.
Radchenko (2023), Figure 2. Myrmica rudis, worker, neotype: (A) body, right side lateral view; (B) body, left side dorso-lateral view; (C) hind tibia; Myrmica intermedia, workers: neotype (D) body, left side lateral view; (E) body, right side dorso-lateral view; specimen GPIH 4942: (F) head, dorsal view; (G) body, dorsal view; specimen F-650: (H) body, dorso-lateral view; (I) antenna. Scale bars: A, B, D, E, G–I – 1 mm, C, F – 0.5 mm.
Radchenko (2023), Figure 4. Myrmica dictyosa, worker, holotype: (A) body, dorsal view; (B) scape; Myrmica damzeni, worker, holotype: (C) body, lateral view; Myrmica saxonica, worker, holotype: (D) body, dorsal view; (E) head, dorso-lateral view; (F) waist and propodeum, dorsolateral view. Scale bars: A, C, D – 1 mm, B, E, F – 0.5 mm.
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2
return to couplet #1
- Entire mesosoma reticulated; propodeal spines directed mainly backward and strongly divergent (ESD/ESL 1.09) (Fig. 4, A). Meso- and metatibiae without spusr. Eyes located in front of midlength of sides of head (GL/OL 1.00). Scape gradually, but quite strongly curved at base (Fig. 4, B) => Myrmica dictyosa
- At least propodeal dorsum (often also sides of mesosoma) with longitudinal rugae (Figs 1, C, D; 2, A, B, D, E, G, H; 3, A, C, D; 4, C, D). Meso- and metatibiae with or without spurs. Position of eyes, shape of scape and propodeal spines varied => 3
- Radchenko (2023), Figure 1. Myrmica paradoxa, workers: (A) holotype and paratype, general view (arrows indicate propodeal teeth); (B) holotype, head and antenna (arrows indicate shape of frontal carina and 3-segmented funicular club); Myrmica longispinosa, worker, neotype: (C) body, right side lateral view; (D) body, left side dorso-lateral view; (E) hind tibia. Scale bars: A–D – 1 mm, E – 0.5 mm.
- Radchenko (2023), Figure 2. Myrmica rudis, worker, neotype: (A) body, right side lateral view; (B) body, left side dorso-lateral view; (C) hind tibia; Myrmica intermedia, workers: neotype (D) body, left side lateral view; (E) body, right side dorso-lateral view; specimen GPIH 4942: (F) head, dorsal view; (G) body, dorsal view; specimen F-650: (H) body, dorso-lateral view; (I) antenna. Scale bars: A, B, D, E, G–I – 1 mm, C, F – 0.5 mm.
- Radchenko (2023), Figure 4. Myrmica dictyosa, worker, holotype: (A) body, dorsal view; (B) scape; Myrmica damzeni, worker, holotype: (C) body, lateral view; Myrmica saxonica, worker, holotype: (D) body, dorsal view; (E) head, dorso-lateral view; (F) waist and propodeum, dorsolateral view. Scale bars: A, C, D – 1 mm, B, E, F – 0.5 mm.
3
return to couplet #2
- Mesosoma relatively short and robust (ML/MH ≤ 2.50); petiole relative short and high (PL/PH < 1.30) (Figs. 3, C, D; 4, D, F) => 4
- Mesosoma long and slender (ML/MH > 2.85); petiole long and low (PL/PH > 1.50) (Figs 1, C, D; 2, A, B, D, E, G, H; 3, A; 4, C) => 5
- Radchenko (2023), Figure 1. Myrmica paradoxa, workers: (A) holotype and paratype, general view (arrows indicate propodeal teeth); (B) holotype, head and antenna (arrows indicate shape of frontal carina and 3-segmented funicular club); Myrmica longispinosa, worker, neotype: (C) body, right side lateral view; (D) body, left side dorso-lateral view; (E) hind tibia. Scale bars: A–D – 1 mm, E – 0.5 mm.
- Radchenko (2023), Figure 2. Myrmica rudis, worker, neotype: (A) body, right side lateral view; (B) body, left side dorso-lateral view; (C) hind tibia; Myrmica intermedia, workers: neotype (D) body, left side lateral view; (E) body, right side dorso-lateral view; specimen GPIH 4942: (F) head, dorsal view; (G) body, dorsal view; specimen F-650: (H) body, dorso-lateral view; (I) antenna. Scale bars: A, B, D, E, G–I – 1 mm, C, F – 0.5 mm.
- Radchenko (2023), Figure 4. Myrmica dictyosa, worker, holotype: (A) body, dorsal view; (B) scape; Myrmica damzeni, worker, holotype: (C) body, lateral view; Myrmica saxonica, worker, holotype: (D) body, dorsal view; (E) head, dorso-lateral view; (F) waist and propodeum, dorsolateral view. Scale bars: A, C, D – 1 mm, B, E, F – 0.5 mm.
4
return to couplet #3
- Meso- and metatibiae without spusr (Fig. 3, E). Head, mesosoma and waist very coarsely sculptured; propodeal spines longer (ESL/HL > 0.55), curved down along their length and weakly divergent (ESD/ESL < 0.90) (Fig. 3, C, D) => Myrmica electrina
- At least metatibiae with pectinate (or at least barbulate) spurs. Head, mesosoma and waist finely sculptured; propodeal spines shorter (ESL/HL 0.38), strongly widened at base, massive, somewhat curved inward and distinctly divergent (ESD/ESL 1.11) (Fig. 4, D-F) => Myrmica saxonica
- Radchenko (2023), Figure 4. Myrmica dictyosa, worker, holotype: (A) body, dorsal view; (B) scape; Myrmica damzeni, worker, holotype: (C) body, lateral view; Myrmica saxonica, worker, holotype: (D) body, dorsal view; (E) head, dorso-lateral view; (F) waist and propodeum, dorsolateral view. Scale bars: A, C, D – 1 mm, B, E, F – 0.5 mm.
5
return to couplet #3
- Eyes located in front of midlength of sides of head (GL/OL < 1.15) (Fig. 2, A, B, D, E). Meso- and metatibiae without spurs (Fig. 2, C) => 6
- Eyes located at midlength of sides of head (GL/OL > 1.25) (Figs 1, C, D; 3, A; 4, C). Meso- and metatibiae with or without spurs => 7
- Radchenko (2023), Figure 2. Myrmica rudis, worker, neotype: (A) body, right side lateral view; (B) body, left side dorso-lateral view; (C) hind tibia; Myrmica intermedia, workers: neotype (D) body, left side lateral view; (E) body, right side dorso-lateral view; specimen GPIH 4942: (F) head, dorsal view; (G) body, dorsal view; specimen F-650: (H) body, dorso-lateral view; (I) antenna. Scale bars: A, B, D, E, G–I – 1 mm, C, F – 0.5 mm.
- Radchenko (2023), Figure 1. Myrmica paradoxa, workers: (A) holotype and paratype, general view (arrows indicate propodeal teeth); (B) holotype, head and antenna (arrows indicate shape of frontal carina and 3-segmented funicular club); Myrmica longispinosa, worker, neotype: (C) body, right side lateral view; (D) body, left side dorso-lateral view; (E) hind tibia. Scale bars: A–D – 1 mm, E – 0.5 mm.
- Radchenko (2023), Figure 4. Myrmica dictyosa, worker, holotype: (A) body, dorsal view; (B) scape; Myrmica damzeni, worker, holotype: (C) body, lateral view; Myrmica saxonica, worker, holotype: (D) body, dorsal view; (E) head, dorso-lateral view; (F) waist and propodeum, dorsolateral view. Scale bars: A, C, D – 1 mm, B, E, F – 0.5 mm.
6
return to couplet #5
- Propodeal spines somewhat longer (ESL/HL ≥ 0.60), directed backward and upward at an angle ca. 45° and strongly divergent (ESD/ESL > 0.95) (Fig. 2, A, B) => Myrmica rudis
- Propodeal spines somewhat shorter (ESL/HL ≤ 0.50), directed mainly backward at an angle ca. 40° and weakly divergent (ESD/ESL < 0.85) (Fig. 2, D, E) => Myrmica intermedia
- Radchenko (2023), Figure 2. Myrmica rudis, worker, neotype: (A) body, right side lateral view; (B) body, left side dorso-lateral view; (C) hind tibia; Myrmica intermedia, workers: neotype (D) body, left side lateral view; (E) body, right side dorso-lateral view; specimen GPIH 4942: (F) head, dorsal view; (G) body, dorsal view; specimen F-650: (H) body, dorso-lateral view; (I) antenna. Scale bars: A, B, D, E, G–I – 1 mm, C, F – 0.5 mm.
7
return to couplet #5
- Meso- and metatibiae without spurs. Propodeal spines somewhat shorter (ESL/HL 0.45); body with very sparse scattered thin suberect hairs, appears almost hairless; scape and legs with sparse thin decumbent hairs (Fig. 4, C) => Myrmica damzeni
- Meso- and metatibiae with pectinate spur (Fig. 1, E). Propodeal spines longer (ESL/HL > 0.55); body with numerous erect to suberect hairs; scape and legs with abundant suberect hairs (Figs 1, C, D; 3, A) => 8
- Radchenko (2023), Figure 4. Myrmica dictyosa, worker, holotype: (A) body, dorsal view; (B) scape; Myrmica damzeni, worker, holotype: (C) body, lateral view; Myrmica saxonica, worker, holotype: (D) body, dorsal view; (E) head, dorso-lateral view; (F) waist and propodeum, dorsolateral view. Scale bars: A, C, D – 1 mm, B, E, F – 0.5 mm.
- Radchenko (2023), Figure 1. Myrmica paradoxa, workers: (A) holotype and paratype, general view (arrows indicate propodeal teeth); (B) holotype, head and antenna (arrows indicate shape of frontal carina and 3-segmented funicular club); Myrmica longispinosa, worker, neotype: (C) body, right side lateral view; (D) body, left side dorso-lateral view; (E) hind tibia. Scale bars: A–D – 1 mm, E – 0.5 mm.
8
return to couplet #7
- Propodeal spines weakly divergent (ESD/ESL < 0.85) (Fig. 1, D). Scape gradually but quite strongly curved at base (similar to Myrmica sulcinodis) => Myrmica longispinosa
- Propodeal spines strongly divergent (ESD/ESL > 0.95) (Fig. 3, B). Scape very feebly curved at base (similar to Myrmica rubra) => Myrmica eocenica
- Radchenko (2023), Figure 1. Myrmica paradoxa, workers: (A) holotype and paratype, general view (arrows indicate propodeal teeth); (B) holotype, head and antenna (arrows indicate shape of frontal carina and 3-segmented funicular club); Myrmica longispinosa, worker, neotype: (C) body, right side lateral view; (D) body, left side dorso-lateral view; (E) hind tibia. Scale bars: A–D – 1 mm, E – 0.5 mm.