Xylolaemus richardklebsi Alekseev et Bukejs, 2016

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 : 227-229

Xylolaemus richardklebsi Alekseev et Bukejs, 2016

( Figs 33–36 )

Material examined. One specimen with collection number JDC-12545 [ JDC], Baltic amber; adult, sex unknown ( Fig. 33 ) . A complete beetle is included in a transparent, yellow amber piece with dimensions of 23× 17 mm and a maximum thickness of 7 mm, preserved without supplementary fixation. Ventral portion of specimen is obscured by cracks and ‘milky’ opacity within amber. Syninclusions: one Formicidae ( Hymenoptera ) specimen; large leg of? Araneae ; few stellate Fagaceae trichomes; and numerous minute detrital particles.

One specimen with collection number JDC-12546 [ JDC], Baltic amber; adult, sex unknown ( Figs 34–35 ). A complete beetle with partially exposed metathoracic wings is included in a transparent, yellow amber piece with dimensions of 25× 23 mm and a maximum thickness of 8 mm, preserved without supplementary fixation. Ventral portion of specimen is visible, partially obscured by gas bubble on right side. Syninclusions: few stellate Fagaceae trichomes.

One specimen with collection number No. KA-CLP-002 [ CKVA], Baltic amber; adult, sex unknown ( Fig. 36 ). A complete beetle included in a transparent, yellow amber piece with dimensions of 20× 27 mm and a maximum thickness of 4 mm, preserved without supplementary fixation. Syninclusions: one specimen of Hymenoptera (? Chalcididae ).

Note. Body length of beetle JDC-12545 (including visible part of head) 3.9 mm, maximum body width 1.4 mm. This specimen has a dilated antennomere 10, elytra without fascicules, pronotum with longitudinal impression at middle, and about 10–12 small denticles on each side of pronotum laterally. Although the specimen is slightly smaller than the holotype, and it is obscured for study on the ventral side, no morphological differences were found, and the specimen is assigned to extinct X. richardklebsi .

Body length of beetle JDC-12546 (including visible part of head) 3.4 mm, maximum body width 1.2 mm. This specimen has dilated antennomere 10, elytra without fascicules, pronotum with distinct longitudinal impression medially, and 12 small denticles on each side of pronotum laterally. While the specimen is smaller than the holotype, no morphological differences were found, and the specimen is assigned to extinct X. richardklebsi .

Body length of beetle KA-CLP-002 (including visible part of head) 4.25 mm, maximum body width 1.5 mm. Although the specimen is slightly larger than the holotype, no morphological differences were found and the specimen is assigned to extinct X. richardklebsi .

Our study of Zopheridae amber inclusions in Baltic amber (including present material and specimens not considered in the current publication) shows that X. richardklebsi was abundant in the Eocene amberiferous forests of Fennosarmatia, and that it is seemingly the most common inclusion among the Baltic amber zopherid species.

Figures

FIGURES 33–38. Fossil Xylolaemus in Baltic amber: 33—X. richardklebsi, specimen No. JDC-12545 [JDC], habitus in dorsal view; 34—X. richardklebsi, specimen No. JDC-12546 [JDC], 34—habitus in dorsal view; 35—idem, habitus in ventral view; 36—X. richardklebsi, specimen No. KA-CLP-002 [CKVA], habitus in dorsal view; 37—X. legalovi, specimen No. KA-CLP- 003 [CKVA], 37—habitus in dorsal view, 38—idem, habitus in lateral view. Scale bars = 1.0 mm.