Melandryidae, Leach, 1815

Alekseev, Vitalii Igorevich & Bukejs, Andris, 2021, Fossil Melandryidae (Coleoptera: Tenebrionoidea) from Eocene Baltic amber of the Sambian peninsula: new genus, six new species, new records and key to described taxa, Zootaxa 4965 (1), pp. 142-166 : 164-165

Key to adult Melandryidae known from Eocene amber

1. Metatibial spurs longer than one-half length of metatibia, antennae clavate....................................... 2

- Metatibial spurs short, not longer than width of metatibia at apex, antennae non-clubbed............................. 6

2. Body oblong, spindle-shaped, longer than 2.5 mm; antennal club 4-segmented.................................... 3

- Body sub-globose, shorter than 2.5 mm; antennal club 3-segmented............................................ 5

3. Elytra with longitudinal furrows; metatibial spurs as long as metatarsomere 1; smaller, body length 2.7 mm ............................................................................... Orchesia canaliculata Alekseev & Bukejs

- Elytra without longitudinal furrows, metatibial spurs slightly shorter than metatarsomere 1; larger, body length greater than 3.0 mm ................................................................................................ 4

4. Elytra with transverse rugosity in basal 1/10; antennomere 11 more than twice as long as antennomere 10; larger, body length 3.6–4.1 mm .................................................................. Orchesia rasnitzyni Nikitsky

- Elytra without transverse rugosity; antennomere 11 1.7× longer than antennomere 10; smaller, body length 3.25–3.6 mm ........................................................................ Orchesia turkini Alekseev & Bukejs

5. Scutellar shield with rounded sides; sutural stria not reaching scutellar shield anteriorly; smaller and comparatively broader, body length 1.5 mm ......................................................... Microscapha kugelanni sp. nov.

- Scutellar shield triangular, with straight sides; sutural stria reaching scutellar shield anteriorly; larger and comparatively more elongate, body length 1.7–1.8 mm ..................................... Microscapha andrzeji Bukejs & Alekseev

6. Antennae long, not shorter than one-half of body length...................................................... 7

- Antennae shorter than one-half of body length............................................................. 12

7. Penultimate metatarsomere bilobed...................................................................... 8

- Penultimate metatarsomere simple, cylindrical.............................................................. 9

8. Antennomeres widened distally, conical; procoxae separated by prosternal process; pronotum wider than elytra at humeri; body length about 2.7 mm ..................................................... Electroabdera marisbaltici Alekseev

- Antennomeres cylindrical; procoxae contiguous, pronotum narrower than elytra at humeri; body length about 2.2 mm ............................................................................ Quasianisoxya curonensis Alekseev

9. Last maxillary palpomere short, triangular; metatibial spurs equal in length; smaller, body length 3.5 mm ................................................................................................ Abderina helmi Seidlitz

- Last maxillary palpomere elongate, cultriform; metatibial spurs of different length; meso- and metatibae with distinct transverse ridges; body larger than 4.0 mm................................................................... 10

10. Meso- and metatibiae with 12-14 transverse ridges; body length 6.5–9.5 mm .......... Serropalpus ingemmescus Alekseev

- Meso- and metatibiae with 6-8 transverse ridges........................................................... 11

11. Mesosternal process slightly concave apically; elytra without furrows; body length 4.5–5.2 mm .............................................................................................. Serropalpus ryzhkovianus Alekseev

- Apex of mesosternal process squarely truncated; elytra with shallow furrows; body length 7.4–7.6 mm ............................................................................................... Serropalpus vivax Alekseev

12. Head horizontally oriented, distinctly visible in dorsal view; pronotum slightly narrower than elytra at base; metatibial spurs short, about as long as one-half metatibial width at apex..................................................... 13

- Head vertically oriented, usually not visible in dorsal view; pronotum not narrower than elytra at base; metatibial spurs shorter or equal to metatibial width at apex..................................................................... 16

13. Pronotum without triangular basal impressions; fronto-clypeal suture distinct, impressed; last maxillary palpomere subtriangular................................................................................................ 14

- Pronotum with two basal triangular impressions; fronto-clypeal suture poorly discernible, not impressed; last maxillary pal- pomere elongate and cultriform......................................................................... 15

14. Base of pronotum with two small rounded basal impressions; elytron about 3.5× longer than pronotum; body length 2.1 mm .............................................................................. Symphora pollocki sp. nov.

- Base of pronotum without rounded basal impressions; elytron about 5× longer than pronotum; body length 2.3–3.2 mm .............................................................................. Symphora glaesonauta sp. nov.

15. Dorsal pubescence inconspicuous and decumbent; metatarsomere 2 as long as one-quarter of metatarsomere 1; body length 3.3–5.8 mm .................................................. Madelinia gedanoposita Alekseev & Pankowski

- Dorsal pubescence longer, conspicuous, including sparse erect hairs; metatarsomere 2 as long as one-half of metatarsomere 1; body length 4.2 mm ............................................................. Madelinia capillata sp. nov.

16. Last maxillary palpomere elongate, cultriform; metatibial spurs equal to metatibial width at apex; body larger than 5.0 mm.. .................................................................................................. 17

- Last maxillary palpomere triangular, rounded; metatibial spurs shorter; body smaller than 4.5 mm .................... 18

17. Last maxillary palpomere as wide as penultimate; penultimate tarsomeres bilobed; body length 6.7 mm ........................................................................................... Phloiotrya inmarinata sp. nov.

- Last maxillary palpomere distinctly wider than penultimate; penultimate meso- and metatarsomeres simple; body length 5.1 mm ........................................................... Electroxylita chronographica gen. et sp. nov.

18. Body more elongate (ratio of body length:width 2.6); metatarsomere 1 not longer than metatarsomeres 2–4 combined; smaller, body length 2.5–3.5 mm ....................................................... Abdera hoffeinsorum Alekseev

- Body wider (ratio of body length:width 2.2); metatarsomere 1 longer than metatarsomeres 2–4 combined; larger, body length 3.1–4.2 mm .................................................................. Abdera rikojotensis Alekseev