Praeanchodemus punctaticeps sp.

Will, Kipling, 2017, Description of the first flightless platynine ground beetle preserved in Baltic amber (Coleoptera: Carabidae), Zootaxa 4318 (1), pp. 110-122 : 114-115

Praeanchodemus punctaticeps sp. n.

FigS. 1-18 .

Holotype. Female in Baltic amber; Size of amber piece 14.0 x 7.0 x 6.5 mm, with collection number BB-1752-K in StaatlicheS MuSeum für Naturkunde, Stuttgart, Germany ( Fig. 4 ).

Preservation status. The amber piece iS clear and in a good conServation State, however, the embedded Platynini foSSil iS only partly viSible uSing light microScopy due to Several flowlineS adjoining the beetle body ( FigS 1-3 ). Six (left antenna) reSpectively three (right antenna) apical antennomereS are loSt. The hind coxa iS covered by milky coating. The left elytron appearS artificially inflated. The foSSilized exoSkeleton of the Specimen iS in partS markedly Shrunken and thuS diSSociated from the incluSion wall ( FigS. 8-11 ). However, moSt detailS of diagnoStic importance of the external morphology could be reconStructed baSed on both, the remainS of the foSSilized exoSkeleton and the negative imprint of the beetle body on the incluSion wall, uSing micro-CT ( FigS. 5- 17 ).

Syninclusions. No SynincluSionS except for a few dirt particleS.

Description. See diagnoSiS and deScription chapterS of the monotypic genuS above.

MeaSurementS: Body length 5.4 mm; length of head (from tip of half-opened mandible to cervical collar) 1.1 mm; width of head between eyeS 0.9 mm; length of pronotum along midline 1.05 mm; width of pronotum 1.3 mm; length of right elytron (from baSe of Scutellum to apex) 3.3 mm; maximum width of right elytron 0.9 mm. ConSequently, the maximum width of elytra Should be approximately 1.5 mm; the inflated left elytron waS not meaSured.

ProportionS: Width of pronotum/width of head = 1.43; width/length of pronotum = 1.23; width of pronotum/ width of pronotal baSe between laterobaSal angleS = 1.22; length/width of elytra uSing two timeS width of right elytron = 1.64; width of pronotum/ width of elytra uSing two timeS width of right elytron = 1.40.

Colour: Unicoloured dark and Shiny, probably Slightly metallic, however, not clearly diStinguiShable in the foSSil Specimen.

Etymology. The SpecieS epithet referS to the markedly punctate head which iS a conSpicuouS character of the new taxon.

Figures

FIGURES 1 – 4. Praeanchodemus punctaticeps sp. n., light microscopic images of the holotype. Fig. 1, dorsal aspect. Fig. 2, Ventral aspect. Fig. 3, left lateral aspect. Fig. 4, general View with contours of the amber piece.

FIGURES 5 – 9. Praeanchodemus punctaticeps sp. n., Volume rendering of the holotype. Fig. 5, anterior part of body, dorsal aspect; the arrows point to the insertions of the supraorbital setae, pronotal lateral and laterobasal seta, and parascutellar seta. Figs 6 – 7, Ventral aspect of head using different grayscale thresholds; the arrows point to the insertions of the setae at the mentum tooth and at the submentum. Fig. 8, anterior part of body, right dorsolateral aspect. Fig. 9, elytra, View from caudat; the arrows point to the insertions of the third discal seta and the subapical seta. Note in Figs. 8 – 9 that the fossilized exoskeleton is markedly dissociated from the inclusion wall (= the negatiVe imprint of the beetle body).

FIGURES 10 – 14. Praeanchodemus punctaticeps sp. n., Volume rendering of the holotype. Figs 10 – 11, elytra using different grayscale thresholds; the arrows point to the insertions of the discal setae (note that the fossilized left elytron is markedly dissociated from the inclusion wall). Fig. 12, left lateral aspect of pro-, meso-, and metathorax; the arrow points to the insertion of the seta at the mesocoxal ridge. Fig. 13, coxa, trochanter, and femoral base of hind legs; the arrows point to the insertion points of setae (see text for details). Fig. 14, abdominal sternites V-VII; the arrows point to the insertions of the two pairs of setae near apical margin of the seVenth sternite. AbbreViations: mep: metepisternum; mscx: mesocoxa; mtcx: metacoxa; pcx: procoxa.

FIGURES 15 – 17. Praeanchodemus punctaticeps sp. n., Volume rendering of the holotype. Figs 15, anterior part of body, right lateral aspect. Fig. 16, posterior part of body, right lateral aspect; the arrows point to the insertions of the setae of the elytral umbilical series. Fig. 17, seVenth abdominal segment and caudal parts of the female genital using different grayscale thresholds (17 a – b), and reconstructed shape of the gonocoxites (17 c). AbbreViations: acxt: apical gonocoxite; bcxt: basal gonocoxite.

FIGURE 18. Praeanchodemus punctaticeps sp. n., reconstruction of the external shape in dorsal View.