Orchesia (Orchestera) canaliculata, Alekseev, Vitalii I. & Bukejs, Andris, 2015

Alekseev, Vitalii I. & Bukejs, Andris, 2015, A new species of the genus Orchesia Latreille (Coleoptera: Melandryidae) from Baltic amber with a key to species described from fossil resins, Zootaxa 3947 (4), pp. 590-596 : 591-593

Orchesia (Orchestera) canaliculata sp. nov.

( Figs 1–6 )

Type material. Holotype: Nr. AWI-055 [ CVIA], possible male. The complete beetle is included in small, transparent, polished amber piece in the form of almost equilateral triangle (with lateral lengths 16 x 16 x 15 mm and maximum thickness 7 mm), yellowish in color, without supplementary fixation. Other animal syninclusions are absent, and plant syninclusions are represented by some small, dark pieces of organic matter and one stellate fagacean trichome.

Type strata. Baltic Amber, Upper Eocene, Prussian Formation (Priabonian). Estimated age: 37.2–33.9 Ma.

Type locality. Yantarny village [formerly Palmnicken], the Sambian [Samland] peninsula, Kaliningrad region, Russia.

Diagnosis. This new species belong to subgenus Orchestera Guillebeau, 1887 . This suggestion is based on two morphological characters which are diagnostic for this subgenus: 4-segmented antennal club and relatively narrow frontal area between eyes ( Nikitsky 2011). O. canaliculata sp. nov. differs from all described fossil species of Orchesia ( O. rasnitzyni Nikitsky, 2011 ; O. turkini Alekseev & Bukejs, 2012 ) in longer antennomere 1 (about 1.4 times as long as antennomere 2), longer metatibial spurs (equal in length to first metatarsomere), presence of shallow furrows on elytra, and shorter body length. This new species is similar to recent O. (Orchestera) luteipalpis Mulsant & Guillebeau, 1857 but differs in furrowed elytra, longer metatibial spurs, and shorter body length.

Description. Body length 2.7 mm (along midline from anterior margin of frons to abdominal apex), width 0.9 mm (at widest part of elytra); oblong, spindle-shaped, weakly convex; unicolorous fulvous; dorsally covered with short, dense, recumbent hairs.

Head inflexed downwards, densely and finely punctate. Eyes lateral, large, reniform and slightly prominent, with distinct facets larger than punctures on head. Frons between eyes narrow, with width equal to 0.5 times vertical diameter of one eye. Interantennal space narrow, about 1.5 times as wide as eye diameter. Antennae 11- segmented, clavate, inserted between and close to inner margin of eyes; short, reaching basal 1/5 of elytra; antennal club 4-segmented, relatively loose; length ratios of antennomeres 1-11: 7-5-4-4-3-3-3-3-4-4-6. First antennomere long cylindrical, about 4 times as long as wide. Maxillary palpi large (half as long as antenna), 4-segmented: basal palpomere minute; palpomeres 2 and 3 approximately equal in length, triangular; palpomere 4 large, cultriform; length ratios of palpomeres 1–4: 1-3-3-9.

Pronotum transverse, approximately 1.5 times as wide as long, broadest at base; with homogenous fine and dense punctures, interspaces smaller than one puncture diameter; lateral sides weakly rounded, gradually narrowed to anterior margin, posterior angles rounded, base weakly sinuate; with two shallow basolateral impressions.

Scutellum small, flat, widely rounded apically. Elytra gradually narrowed from base to apex; 2.3 times longer than wide (length 2.1 mm, max. width 0.9 mm); with clearly visible complete sutural stria reaching apex of elytra. Elytral punctures fine and dense. Each elytron with 4–5 very shallow furrows, intervals weakly convex on disc only.

Ventral surface covered with fine, dense and relatively homogenous punctures. Epipleura wide in anterior part and gradually narrowing posteriorly, extending to elytral apex. Metepisternum 4.6 times as long as wide. Metacoxae large, transverse, wider than metafemora. Abdominal ventrites 1 and 2 large, equal in length; length ratios of ventrites 1–5: 15-15-12-10 -10.

Legs moderately long; all tibiae and femora flattened; hind legs most robust; metatibiae distinctly dilated anteriorly, 0.7 times as long as mesotibiae. Mesotibiae with two spurs of different lengths (proportions 2:3); metatibiae with two equally long spurs, equal in length to metatarsomere 1. Protarsus equal in length to protibia, mesotarsus slightly longer than mesotibia, metatarsus 2.5 times as long as metatibia. Tarsal formula 5-5-4. Protarsi distinctly dilated, penultimate segment bilobed. Length ratios of protarsomeres 1–5: 5-5-5-5-6; length ratios of mesotarsomeres 1–5: 16-7-5-3-9; length ratios of metatarsomeres 1–4: 6-3-2-2. Claws simple, free, small.

Etymology. The epithet of this new species [Latin “canaliculatus” – grooved] refers to its furrowed elytra. Note. The distinctly dilated protarsi suggests that the specimen is probably male.

Figures

FIGURES 1 – 4. Orchesia canaliculata sp. nov., holotype. 1) habitus, dorso-lateral view; 2) habitus, lateral view; 3) habitus, dorsal view; 4) details of abdomen, matathorax and elytra, lateral view. Scale bar – 1 mm.

FIGURES 5 – 6. Orchesia canaliculata sp. nov., holotype. 5) head, frontal view (reconstruction); 6) hind leg (reconstruction).