Cycadophila Xu, Tang & Skelley, 2015

Alekseev, Vitalii I. & Bukejs, Andris, 2017, First fossil representatives of Pharaxonothinae Crowson (Coleoptera: Erotylidae): indirect evidence for cycads existence in Baltic amber forest, Zootaxa 4337 (3), pp. 413-422 : 414

Genus Cycadophila Xu, Tang & Skelley, 2015

Note. The specimens considered here were assigned to the subfamily Pharaxonothinae based on a combination of the following visible external morphological characters: (1) lateral pockets on the mentum present; (2) tarsal shelf of tarsomere 5 absent; (3) metepisternal ctenidium absent; (4) antennal insertion hidden in dorsal view; (4) anterior angles of pronotum poorly developed; (5) mesometaventral articulation monocondylic; (6) ventrite 1 without subcoxal lines. According to Leschen (2003), the above mentioned combination of characters (especially possession of distinct lateral pockets on the mentum) can distinguish these specimens from the habitually similar representatives of the subfamily Xenoscelinae . However, characters not visible or that require dissection are needed to unequivocally confirm placement in the Pharaxonothinae .

Within the Pharaxonothinae , these fossils were assigned to the genus Cycadophila based on: (1) large eyes that encroach upon head ventrally; (2) 11-segmented antennae with a 3-segmented antennal club not flattened; (3) pro- and mesocoxal cavities open; (4) supraocular stria present, not extending posteriorly beyond eyes; (5) pronotal callosity absent; (6) elytra glabrous with non-impressed rows of punctures; (7) pronotum with narrow basal sulci; (8) submentum separated from gula by transverse impression (submental-gular suture); (9) 5-segmented tarsi with tarsomeres 1–3 pubescent ventrally with long, fine, dense, distally directed setae, not lobed beneath.

According to the up-to-date key of Skelley et al. (2017), the studied extinct specimens can be assigned to the subgenus Cycadophila Xu, Tang & Skelley, 2015 due to (1) lateral pronotal carinae narrow in lateral view, and (2) protibia without stout setae along lateral margin. Several morphological characters (e.g. head swollen dorsally; clypeus convex in lateral view; ventral interocular distance 0.58× head width; pronotal surface near anterior angles slightly impressed; pronotal lateral carinae parallel most length; elytra without colour patterns) allow placement of these specimens in the extant nigra species group. This placement is tentative and not irreproachable at the moment, because the shape of the prosternal process is not clear due to the position of the legs, and anterior pronotal angles are not sharply angulate as is typical for the nigra species group.