Bioacoustics of Platynus (Platynus) hoffeinsorum

Etymology. The new species is dedicated to Christel and Hans Werner Hoffeins, Hamburg, for their diverse contributions to the study of arthropods in amber. Species group recognition and differential diagnosis. Tribus: A species of the tribe Platynini based on the combination of the following characters: 1) mandibular scrobe asetose; 2) penultimate article of maxillary palpus bisetose; 3) two pairs of supraorbital setae present in normal position; 4) head and pronotum without stridulating mechanism; 5) elytra with dorsal setae in third interval; 6) elytra with apical margin entire, not truncate; 7) elytra without internal plica; 8) prosternal process not marginated; 9) anterior coxal cavities closed posteriorly; 10) mesepimeron not reaching the mesocoxal cavities (= mesocoxal cavities conjunct); 11) metepimeron lobe-like dilated; 12) protibia not markedly broadened towards apex, with 13) antennal cleaner organ situated subapically and 14) with groove almost complete on dorsal surface; 15) claws simple, not pectinate. Remarks: The systematic position of the Platynini within the “modern Carabidae ” (= Harpalinae sensu auct.) is still largely unsettled. They are often considered the sister group of Sphodrini (e.g., Habu 1978 , Casale 1988 , Lorenz 2005, Bousquet 2010 ), or even the sister group of a single branch of the latter tribe (Synuchi: Lindroth 1956 ), however, not a single synapomorphy is known that supports these assumptions. In addition, although representatives of the Platynini tribe are relatively easy to recognize (e.g., based on the combination of the character states mentioned above) the currently known diagnostic characters of Platynini seem to be plesiomorphic as well. The combination of the above listed characters 4, 8, 14, and 15, is suitable for differentiation of the fossil specimen from species groups of Sphodrini . Genus: The new fossil species is a representative of the genus Limodromus based on the combination of the following characters: 1) dorsal and ventral surfaces of body glabrous beside normal setation; 2–4) head capsule completely blackish without reddish brown spots, without punctures on disc, and with a distinct constriction towards neck; 5) eyes large and hemispherical; 6) mandible normal, not markedly slender; 7) mentum tooth developed, simple; 8) mentum setae small, inserted very close to each other immediately basad of mentum tooth; 9) third antennomere glabrous, only with a ring of primary setae apically; 10–13) pronotum distinctly broader than head, cordate with laterobasal angles large, with lateral gutter and laterobasal grooves very broad, and with laterobasal seta present; 14) elytra with anterior dorsal seta in third interval present; 15) metacoxa bisetose (inner seta absent); 16) ventral lobes of fourth protarsomeres short, almost symmetric. Remarks: Monophyly of Limodromus is well supported based on at least four synapomorphies of which three are features of the male genital armature ( Schmidt 2000 , 2005). This cannot be determined in L. hoffeinsorum sp. n. because the abdomen is lost in the fossil specimen. The position of the mentum setae as observed in L. hoffeinsorum sp. n. and in other Limodromus species is the fourth proposed synapomorphic character but it is also present in the following four lineages of Platynini : Clade of Agonum Bonelli, 1810 + Agonidium Jeannel, 1948 (see Liebherr & Schmidt 2004 ): In general, species of this clade are easily to recognize based on the derived shape of pronotum with +/- rounded hind angles. In addition, species of Agonidium differ by the antennal pedicellus bearing a ring of setae at apex, species of Europhilus Chaudoir, 1859 differ additionally by the pubescent distal portion of third antennomere, and both the latter taxa as well as Agonum s. str. differ by the very narrow anterior half of the pronotal marginal gutter. In all other lineages of Agonum s.l. (summarized in the subgenus Agonothorax Motschulsky, 1850 = Olisares Motschulsky, 1865 , see Liebherr & Schmidt, 2004 , Liebherr et al. 2005 ), the mentum setae are inserted laterad of the base of the mentum tooth, and thus they are different from Limodromus .