Zopheridae, Solier, 1834

ALEKSEEV, VITALII, MCKELLAR, RYAN C. & BUKEJS, ANDRIS, 2024, A revision and addition to Zopheridae (Coleoptera: Tenebrionoidea) in Baltic amber: possible connections between modern Holarctic distributions and Eocene ‘ amber forests’, Zootaxa 5536 (2), pp. 201-247 : 237-238

4. Key to adult of Zopheridae known from Baltic amber

The following key separates all the zopherid taxa described from Baltic amber. It should be noted that characters are chosen for conspicuousness and ease of recognition, not necessarily because they directly reflect the phylogeny, or are the most important characters in systematics of this group. Representatives of Sarrotriini and Synchitini are especially difficult to distinguish during the study of inclusions. Unequivocal separation of these tribes (at least for the Baltic amber representatives studied with optic tools) is not easy. Identification should be made with use of the full character combination, presented in the key below.

1. Tarsal formula 5-5-4................................................................................... 2

- Protarsi tetramerous................................................................................... 4

2. Antenna moniliform, with weak club; pronotum without anterolateral antennal cavities; body longer than 4.5 mm ( Zopheromimini )........................................................................................................3

- Antenna with distinct 3-segmented club, not moniliform; pronotum with deep anterolateral antennal cavities; body length 4.1 mm ( Usechini )............................................................. Usechus andrushchenkoi sp. nov.

3. Eyes hemispherical; antenna 11-segmented; pronotum evenly arcuate anteriorly; smaller, body length 4.9–5.3 mm ............................................................... Zopheromimus auriborussiensis Alekseev et Nabozhenko

- Eyes longitudinally oval; antenna 10-segmented; pronotum with protruding anterior half that partially covers vertex; larger, body length 6.6–8.2 mm .............................................. Yantaroxenos colydioides Nabozhenko et al.

4. Mesotarsi pentamerous; body strongly elongate (about 4× as long as wide), subcylindrical; metaventrite and abdominal ventrite 1 with femoral lines; body length about 4.0 mm ( Gempylodini )............................ Damzenia groehni Alekseev

- Tarsal formula 4-4-4; body comparatively shorter; metaventrite and abdominal ventrite 1 without femoral lines; body shorter than 4.0 mm......................................................................................... 5

5. Body glabrous with punctate surface; procoxal process with distinctly expanded truncate apex; procoxae widely separated by distance larger than procoxal length; anterior portion of head with two pits ( Pycnomerini )............................ 6

- Body usually setose (at least partially), with surface granulate or coarsely punctate; procoxal process not expanded and not truncate apically; distance between procoxae narrower than one procoxal length; anterior portion of head without two pits.. 7

6. Pronotum elongate, 1.1× as long as wide; antennomere 11 oblong, tapered, distinctly narrower than antennomere 10; body length 2.9 mm ................................................................ Pycnomerus simukovi Alekseev

- Pronotum transverse, 1.2× as wide as long; antennomere 11 transverse, rounded apically, and almost as wide as antennomere 10; body length 3.1 mm ................................................... Pycnomerus agtsteinicus Bukejs et al.

7. Antennae 11-segmented with gradually widened antennomeres, antennal club never distinctly separated; plus antennal setation thick and curved; plus intercoxal process of abdominal ventrite 1 triangular with rounded apex; plus pronotum with more or less straight lateral sides and without prominent anterior angles ( Sarrotriini )....................................... 8

- Some of the following characters present in combination: antennae 10- or 11-segmeneted with antennal club more or less developed (if 10-segmenetd, then distinctly clubbed and finely pubescent); intercoxal process of abdominal ventrite 1 narrowly triangular and acute apically or truncate and broadly rounded apically; pronotum with arcuate lateral sides and with anterior angles prominent ( Synchitini )........................................................................... 9

8. Pronotum with one longitudinal median impression; antennomeres 4–5 slightly elongate, subcylindrical, antennomeres 6–8 subquadrate, as long as wide; body length 3.1 mm ................................... Helioctamenus groehni sp. nov.

- Pronotum with three rounded impressions; antennomeres 4–9 trapezoidal, strongly transverse; body length 2.9 mm ............................................................................ Thanatoplagia tamutisi gen. et sp. nov.

9. Intercoxal process of abdominal ventrite 1 broadly rounded apically; elytra ovate; body length 2.25 mm ..................................................................................... Diodesma slipinskii Alekseev et Bukejs

- Intercoxal process of abdominal ventrite 1 triangular, pointed; elytra almost parallel-sided in anterior two-thirds......... 10

10. Antennal club 3-segmented; pronotum with two pairs of longitudinal carinae; body length 3.5 mm ............................................................................................. Lasconotus tenebrisilvarum sp. nov.

- Antennal club 1- or 2-segmented; pronotum with one pair of longitudinal carinae or not carinate..................... 11

11. Antennae 10-segmented with rounded 1-segmented antennal club.............................................. 12

- Antennae 11-segmented with clearly separated antennomeres 10 and 11......................................... 13

12. Body with distinct setae dorsally; pronotal disc without elevated central area and longitudinal carinae; elytral intervals not carinate; body length 1.93 mm .................................................. Synchita andrisbukejsi Alekseev

- Body without distinct setae dorsally (setation inconspicuous); pronotal disc with elevated central area and two longitudinal carinae; elytral intervals carinate; body length 2.4 mm .................................. Paha vanivanitatum sp. nov.

13. Pronotal disc with two curved admedian costae; pronotal lateral sides widely explanate; body length 2.8–3.5 mm .............................................................................. Endophloeus gorskii Alekseev et Bukejs

- Pronotal disc without costae; pronotal lateral sides not explanate............................................... 14

14. Antennomeres without distinct curved setae; antennal club distinct, antennomeres 10–11 more than 2.0× as wide as antennomere 3–9............................................................................................... 15

- Antennomeres with distinct curved setae; antennal club less distinct, antennomeres 3–9 comparatively wider than antennomeres 10–11............................................................................................. 16

15. Pronotum elongate, 1.3× as long as wide; scutellary striole present; body distinctly elongate (about 3.2× as long as wide); body length 2.75 mm ............................................................... Bitoma glaesisepulta Alekseev

- Pronotum transverse, 1.2× as wide as long; scutellary striole not apparent; body elongate (about 2.9× as long as wide); body length 2.3 mm ............................................................... Coxelus carstengroehni sp. nov.

16. Body convex dorsally, short (about 1.6× as long as wide); eyes vertical, weakly convex, slightly emarginate; body length 1.85 mm ............................................................ Semicoxelus sontagae Alekseev et Pankowski

- Body flattened dorsally, longer (more than 1.6× as long as wide), subparallel-sided; eyes hemispherical; body length larger than 3 mm .............................................................................................. 17

17. Antennal club weak, loose, with antennomere 10 not dilated; pronotum without impression medially; elytra without fascicules; body length 3.2 mm ..................................................... Xylolaemus sakhnovi Alekseev et Lord

- Antennal club more distinct, loose, with antennomere 10 dilated; body length more than 3.2 mm ..................... 18

19. Elytra with fascicules of scales; pronotum without distinct impression medially, covered with large granules and with 7–8 denticles laterally; anterior margin of pronotum strongly arcuate and protrudes anteriad more than pronotal anterior angles; body length 3.5 mm .................................................... Xylolaemus legalovi Alekseev et Bukejs

- Elytra without fascicules of setae; pronotum with distinct longitudinal impression medially, covered with small granules and with 12 small denticles laterally; pronotal anterior angles protrude anteriad more than weakly arcuate pronotal anterior margin; body length 3.4–4.1 mm ............................................. Xylolaemus richardklebsi Alekseev et Bukejs