Vabole Alekseev and Nabozhenko

Alekseev, Vitalii I. & Nabozhenko, Maxim, 2015, A New Fossiltenebrionid Beetle of the Tribe Palorini (Coleoptera: Tenebrionidae) from Eocene Baltic Amber, The Coleopterists Bulletin (mo 14) 69, pp. 127-130 : 128

Family Tenebrionidae Latreille, 1802 Subfamily Tenebrioninae Latreille, 1802 Tribe Palorini Matthews, 2003 Genus Vabole Alekseev and Nabozhenko ,

new genus

Type Species. Vabole triplehorni Alekseev and Nabozhenko , new species.

Etymology. The genus name is derived from the word “vabole” (Latvian for “beetle”). The gender is feminine.

Description. Body small (slightly more than 2 mm in length), oblong, subparallel-sided, strongly flattened, glabrous. Edge of frontoclypeus weakly arcuate. Labrum weakly transverse, subcircular. Antennae without club, 11-segmented, antennomere 11 very small. Antennae moderately long, reaching middle of pronotum, antennomeres 1–10 longer than wide. Apical maxillary palpomere acuminate. Dorsal margin of eye above lateral edge of gena. Pronotum narrowing basally. Prosternal process between procoxae apically widened and rounded, 2 times as broad as diameter of procoxa. Elytra without scutellary striole, scutellum transverse, angulate. Metathoracic wings present. Mesocoxal cavities narrowly closed by ventrites. Abdomen with membranes between abdominal ventrites 3–5. Abdominal ventrite 5 with lateral groove along edge. Tarsomeres subparallel, cylindrical, tarsal formula 4-4-4. All tibiae with strong spines on inner side.

Diagnosis. Vabole must be included in the family Tenebrionidae based on the following characters: antennae inserted under lateral expansions of frons, which conceals at least base of scape dorsally; external membranes visible between abdominal ventrites 3–5 and accordingly abdominal glands are likely to be present. Nearly perfect correlation between the presence of glands and external membranes between abdominal ventrites 3–5 was established by Doyen (1972). With one known exception (the tribe Palorini ), Tenebrionidae with the aedeagus inverted lack defensive glands, while species with the aedeagus in the normal position possess them ( Doyen 1972; Watt 1974). According to Doyen (1972), “the tenebrionid subfamily Tenebrioninae , together with the Alleculidae , Lagriidae and Nilionidae possess defensive glands and external abdominal membranes and have the aedeagus in the normal position”. For this reason, Doyen (1972) treated Tenebrioninae , Alleculinae , Lagriinae , and Nilioninae as subfamilies in the family Tenebrionidae .

Matthews and Bouchard (2008) defined a combination of characters for recognition of the tribe Palorini following the works of Halstead (1967) and Matthews (2003a, b): prominent subquadrate labrum; round or oval eyes; simple antennal sensilla; usually compact antennae; tarsomeres cylindrical, not lobed; mesocoxal cavities usually closed by ventrites; frequently scutellum transverse and aedeagus inverted; scutellary striole absent or not. Vabole has the following combination of tribal characters ( Figs. 1–3 ): round eyes; compact antennae (but with weakly longitudinal antennomeres); unlobed cylindrical tarsomeres; mesocoxal cavities closed by ventrites; transverse, angulate scutellum. Additionally, Vabole has a 4-4-4 tarsal formula, which is characteristic among some tenebrionid genera of the tribes Palorini , Hyocini, Rhipidandrini, and Archaeoglenini , and the subfamily Lagriinae .

Vabole is most similar to the extant genus Platycotylus Oliff, 1883 , which is distributed across Australia (eastern New South Wales, eastern Queensland, Northern Territory), Africa, and Southeast Asia ( Merkl 1992; Matthews and Bouchard 2008; Schawaller 2014), based on its strongly flattened body and longitudinal antennomeres, but differs from this genus and most other Palorini genera in tarsal formula (4-4- 4 in Vabole , Eutermicola Lea, 1916 , and some species of Pseudeba Blackburn, 1903 ; 5-5- 4 in others), the smaller antennomere 11, the presence of strong spines on the inner side of the metatibiae, and the wider prosternal process.

Remarks. The mesoventrite and head are only partly visible ventrally because of gas bubbles.

Stratigraphic and Geographic Range. Eocene amber of Central Europe.

Figures

Figs. 1–3. Vabole triplehorni, habitus. 1) Dorsal view; 2) Ventral view; 3) Lateral view.