Pseudobothrideres rugiorum, Alekseev, 2015

Alekseev, Vitalii I., 2015, Two new cocoon-forming beetles (Coleoptera: Cucujoidea: Bothrideridae) from Baltic amber, Baltic Journal of Coleopterology 15 (1), pp. 9-16 : 10-12

P. rugiorum sp.nov.

( Figs. 1A , 2 A-B, 3A-B)

Material examined. Holotype Nr. 273-1 [ CCHH], sex unknown. The beetle inclusion is preserved in a polished piece of transparent amber with a yellowish shade, possibly thermal processed in an autoclave. The amber piece is embedded in polyester resin (total measurements are 14 x 10 x 6 mm). The syninclusions are represented by four fagacean stellate hairs.

Type strata. Baltic Amber. Eocene.

Description:

Body: elongate, subparallel, dark; dorsal surface with short and small setae that arise from punctures; ventral surface moderately shiny, glabrous. Length 5.25 mm. Width 1.5 mm (in humeral area).

Head: slightly narrowed anteriorly; without supra-ocular ridges, dorsolateral margin almost straight; punctures small and dense (distance between punctures is about twice less than diameter of puncture). Frontoclypeal suture indistinct in the middle, very fine laterally. Anterior margin of clypeus broadly arcuate. Antennal groove well-developed, impunctate. Antennae clavate, stout, sparsely setose, reaching apical 1/3 of pronotum; scape (antennomere I) and pedicel (antennomere II) wide (wider than antennal club), rounded; antennomeres with single transverse row of moderately long setae, setae extending at least to distal margin of antennal segment; antennal club segments with sparse setae, setae long and located at or near distal margin of the segment. Antennal club symmetrical, loose, 2-segmented. Penultimate segment broader than long and broader than last one. Eyes: strongly pr otuber an t, coar sely facetted, lackin g interfacetal setae.

Thorax: Pronotum almost as long as wide, widest near anterior 1/3; distinctly wider than head; trapezoidal in outline; dorsal surface flattened to slightly impressed at middle, convex laterally; anterior margin almost straight; anterior angles triangular, nearly right; posterior margin slightly sinuate, distinctly narrower than elytral bases; posterior angles pronounced. Lateral margins finely bordered basally, with small denticle behind the middle. Pronotal surface with small, dense, longitudinally oval punctures. Pronotal disc with tubercle enclosed by well impressed sulci, with additional more or less parallel sulci. Additional sulci reaching base of pronotum. Punctation of hypomeron elongate and coarse. Prosternum with rounded punctuation, not foveate in front of coxae. Prosternal process between coxae widened apically, roundly impressed, but without transverse suture. Metasternum with long and deep femoral lines almost reaching metacoxa. Scutellum triangularly rounded.

Elytra: Elytra flattened dorsally, convex laterally; jointly rounded apically. Five alternate intervals on each elytron carinate, especially

apically. Suture carinate at apex only. Hind wings are not apparent.

Legs: Relative distances between coxae 3-1-6. Procoxae separated by distance twice width of coxal diameter. Femora and tibiae irregularly and densely punctate. All tibiae with two acute short apical spurs. Protibiae with sharp and long terminal outer teeth, mesotibiae with short apical teeth. Tarsal formula 4-4-4. Last tarsomere the longest; basal tarsomere distinctly longer than second segment and 1.5 times shorter than segments II and III combined; segments II and III equal in size and form. All tarsomeres with sparse long setae ventrally. Tarsal claws are simple, large, equal in size.

Abdomen: with five similarly articulated ventrites; ventrite length proportions according to the formula: 35-15-12-8-15. Ventrite V more densely punctured than preceding segments, impressed. The intercoxal process of abdominal ventrite I truncate, straight.

Differential diagnosis: The specimen 273-1 can be referred to the subfamily Bothriderinae due to the procoxae widely separated by the prosternal process and the full combination of morphological characters of the family (elongate shape, 4-4-4 tarsi, capitate antennae with 11 segments, antennal insertions exposed, five abdominal ventrites). The new fossil species is assigned to the genus Pseudobothrideres Grouvelle, 1908 because of the following characters: elongate, striate-punctate elytra without tubercles and with carinate alternate intervals; 11-segmented antennae with 2-segmented antennal club; upper surface without scales; the trapezoidal in outline pronotum without carinae but with tubercle enclosed by well impressed sulci; not foveate in front of coxae prosternum; apical teeth on mid and anterior tibiae present; apically prosternal process expanded; metasternum with long femoral lines. Pseudobothrideres rugiorum sp.nov. can be distinguished from extant representatives of the genus by the indistinct transverse suture of prosternal process, by the absence of the row of denticles along outer margin of anterior tibia, by the not subequal in length tarsomere I-III (basal mesoand metatarsomere distinctly longer than second one), by the finely bordered pronotum with small denticle behind the middle, by the upper surface with short hair-like setae and by presence of additional sulci on pronotum.

Remarks. The femoral lines of ventrite I, an important character for diagnosis are not visible on the specimen because of the legs position.

Derivatio nominis. Specific epithet is formed from the Rugians (also Rugii, Rygir, Ulmerugi, or Holmrygir), a Germanic tribe of Scandinavian origin, inhabiting the territory of the southern Baltic Sea coast and the island Usedom until the 5th century AD.

Figures

Fig.1. The Baltic amber Pseudobothrideres, reconstructions: A – P. rugiorum sp.nov.; B – P.criwecriwayto sp.nov.

Fig.2. Pseudobothrideres rugiorum sp.nov. Habitus: a) Dorsal view; b) Ventral view.