Palaeoiresina Wiesner, Will, and Schmidt, 2017

Wiesner, Jürgen, Will, Kipling & Schmidt, Joachim, 2017, Two new genera and species of tiger beetles from Baltic amber (Coleoptera: Carabidae: Cicindelinae), Insecta Mundi 2017 (577), pp. 1-14 : 4-6

Palaeoiresina Wiesner, Will, and Schmidt , new genus

Type species. Palaeoiresina cassolai Wiesner, Will, and Schmidt , new species.

Description. Body length: 8.8 mm in the type species.

Head. Moderately broad with eyes rather small, moderately protruded. Mandibles with two teeth of the incisor region, teeth of left mandible longer ( Fig. 18 ). Labrum markedly short, 3.8 times wider than long, with apical margin simple, slightly convexly produced in middle, undentated, with six setae, ( Fig. 17 ). Antennae filiform. Labial palpus with two palpomeres, the basal one sparsely setose, presumable 1.2 times longer than apical palpomere. Maxillary palpus with two visible sparsely setose palpomeres, basal two palpomeres invisible ( Fig. 19 ). Frons and vertex smooth or almost so, supraorbital area densely covered with longitudinal furrows. Two supraorbital setae each side; clypeus with a single seta each side ( Fig. 17 ). Vertex shallowly slanted towards front.

Pronotum. Approximately as long as wide, its maximum width distinctly before the middle, with base almost as broad as apical margin; latter nearly straight with lateroapical angles fully rounded, not protruded. Side margin convex in middle, slightly notched at level of anterior transverse groove, concave at level of posterior transverse groove, finely bordered (border line disappeares near apex). Basal margin moderately convex, distinctly and broadly bordered, with laterobasal angles markedly bent anterior, latter slightly obtuse, rounded at tip, slightly protruded laterally. Disc covered with distinct furrows on the plate. Anterior and posterior transverse grooves moderately deep, intermediate part distinctly globose ( Fig. 19 ).

Elytra. Elongated-ovate, with maximum width at the beginning of the apical third, not fused. Shoulders broad, with humerus suggestively obtuse angulate; lateral margin almost straight before widest point. Anterior part of elytra densely punctured, near anterior margin sparsely covered with setae ( Fig. 13 ; posterior part of elytra is lost in the fossil specimen).

Legs. Slender, of usual cicindelid shape, last tarsomeres with two small claws apically, three basal tarsomeres of protarsi widened.

Etymology. The name is composed of the prefix Palaeo (Greek palaios = ancient) and the name of the subtribe Iresina .

Diagnosis. As the ventral side of the fossil is not visible (see Preservation status of the type specimen below), determination of its systematic position within Cicindelinae is as difficult as in the preceding described species. The glabrous head with six labral and four suborbital setae, the two clypeal setae and the obviously glabrous pronotum, mesepisternum, mesepimeron, and metepisternum (as visible) are indicators for the membership in the subtribe Iresina Rivalier, 1971 . Given its total body length and the sculpture of its surface it somewhat resembles species in the genus Rhytidophaena Bates, 1891 , which is distributed along foothills on the southern slopes of the Himalaya from Pakistan to China. However, the fossil differs markedly by unicolored, undentated labrum, mandibles with two teeth of the incisor region and presence of setae on clypeus.

Palaeoiresina cassolai Wiesner, Will, and Schmidt , new species

( Fig. 13–20 )

Holotype. Male in Baltic amber; size of amber piece approximately 20 x 18 x 7 mm, irregularly cut, deposited in the University of California, Museum of Palaeontology , Berkeley , CA, specimen number UCMP404030 , locality number UCMP IP15208 ( Fig. 14 ).

Preservation status. The embedded fossil borders to the surface of the amber piece so that posterior parts of elytra and abdomen, parts of the left hindleg, and the right antenna, are lost ( Fig. 14–16 ). Several flow lines run through the amber piece and therefore, particularly the ventral parts of the embedded Cicindelini fossil cannot be viewed using light microscopy ( Fig. 14 ). As observed in the previously described Baltic amber inclusion, this fossil exposes few parts of the beetle body for adequate contrasts in the micro-CT analyses and is probably a result of microbial processes during embedding of the beetle in the resin. However, most details of diagnostic importance of the external morphology of the head and pronotum as well as the outline of the anterior part of the elytra were reconstructed based on a combination of the light and X-ray microscopic analyses.

Syninclusions. One tiny Diptera, stellate hairs, several tiny dirt particles.

Description. See diagnosis and description chapters of the monotypic genus above.

Body length. 8.8 mm.

Color. Head, pronotum and elytra seemingly unicolored rufescent-brown, with metallic luster all over.

Head. 1.1 times wider than pronotum. Supraorbital area densely covered with 8–10 moderately deep engraved longitudinal furrows, latter continuing towards disc with few additionally short diagonally furrows ( Fig. 13 , 17 ).

Pronotum. 1.01 times longer than wide, with apical margin 1.02 times broader than basal margin.

Elytra. 1.7 times longer than wide.

Etymology. This species is dedicated in honor of the world-renowned tiger beetle specialist, Fabio Cassola of Rome, who passed away on January 14, 2016, at the age of 77. His lifelong passion for tiger beetles leaves us with a legacy of 203 publications that he authored or co-authored, a body of work that is an extraordinarily important contribution to the knowledge of this group.

Differential diagnosis. This species differs from the above described Palaeopronyssiformia groehni new genus, new species, by its much smaller size, the short undentated labrum and the smaller eyes. It differs from Tetracha cf. carolina , another Cicindelinae species described from Baltic amber, by the shape of the labrum and pronotum. The labrum of T. carolina has four setae only and four short marginal teeth, the pronotum has its maximum width close to its anterior edge, the anterior corners of pronotum are more advanced than the anterior margin of prosternum.

Figures

Figures 17–20. Palaeoiresina cassolai, new genus, new species, volume rendering of the holotype. 17) Head, frontal aspect (the black arrows point to the insertions of the supraorbital setae, the clypeal seta and the labral setae); the reconstructed contour line of the labrum is shown below (the white circles represent the pores of the six labral setae). 18) Anterior part of head with mandibles; the reconstructed contour line of the apical portion of mandibles is shown below. 19) Anterior part of body with head and prothorax, right lateral view; the right apical palpomere of labium is shown based on an additional scan. 20) Pronotum, dorsal aspect. Abbreviations: ant: antenna; ce: compound eye; ga: galea; ita: anterior tooth of incisor region of mandibles; itm: median tooth of incisor region; lam: anterior margin of labrum; lbm: basal margin of labrum; lbp: labial palps; mdb-l: left mandible; mdb-r: right mandible; mxp: maxillary palps; paf: anterior transversal furrow of pronotum; pam: pronotal apical margin; pbf: posterior transversal furrow of pronotum; pbm: pronotal basal margin; pcx: procoxa; sc: antennal scape.

Figures 12–13. Simplified reconstructions of the general habitus of the holotypes. The probable respective outlines of those parts of the body which could not be visualized are marked as dotted lines. 12) Palaeopronyssiformia groehni, new genus, new species. 13) Palaeoiresina cassolai, new genus, new species.

Figures 14–16. Palaeoiresina cassolai, new genus, new species, light microscopic image of the holotype. 14) General view with contours of the amber piece. 15) Dorsal view; the amber piece is broken together with the apical portion of the elytra and makes a hole into the beetle’s abdomen. 16) Lateral view of the anterior portion of body.