Groehnaltica batophiloides Bukejs, Reid and Biondi, 2020

Bukejs, Andris, Reid, Chris A. M. & Biondi, Maurizio, 2020, Groehnaltica batophiloides, a new genus and species of flea-beetles (Coleoptera Chrysomelidae) from Baltic amber, described using X-ray microtomography, Zootaxa 4859 (3), pp. 397-408 : 403-406

Groehnaltica batophiloides Bukejs, Reid and Biondi , sp. nov.

( Figs. 1–17 ; Appendices 1–4) http://zoobank.org/ urn:lsid:zoobank.org:act:420E9217-A712-4B73-A62D-88E8F86276A2

Type material. Holotype: “C 7806”, deposited in GPIH collections; adult, male. A complete beetle is included in a transparent, yellow amber piece with dimensions of 14×10× 3 mm, and preserved without supplementary fixation. Syninclusions are absent.

Type strata. A predominantly Bartonian age is interpreted for the extinct Central European resin-producing forests, which produced the amber that has eroded out of Eocene Blue Earth layers (Bukejs et al. 2019).

Type locality. Baltic Sea coast, Yantarny settlement (formerly Palmnicken), Sambian (Samland) Peninsula, Kaliningrad Region, Russia .

Description. Measurements: body length 1.7 mm, body maximum width 0.85 mm; pronotal length 0.4 mm, maximum pronotal width 0.6 mm; elytral length 1.2 mm, maximum elytral width 0.85 mm.

Body ovate, moderately convex; integument reddish brown (as preserved) with antennae, mouth parts, fore and middle legs, and metatarsus paler (pale brown to yellow); glabrous dorsally, abdomen sparsely covered with fine, short, semierect setae.

Head. Without distinct punctation; head together with eyes slightly narrower than anterior margin of pronotum. Vertex slightly convex. Eyes large, prominent, entire, with distinct facets, oval, with vertical length 1.4× transverse width measurement; distance between eyes equal to about 1× transverse width of eye. Frontal calli lanceolate, rather wide (slightly narrower than diameter of antennal socket), oblique, almost flat, not contiguous, and not well delineated from vertex and frontoclypeal carina. Supracallar sulcus poorly developed. Frontoclypeal carina well developed, convex, narrow, about 0.6× as wide as diameter of antennal socket. Orbit narrow, about 0.5× diameter of antennal socket. Orbital sulcus deep, curved. Supraorbital sulcus moderately developed, shallow, almost straight. Supraorbital trichobothrium not visible. Genae impunctate, with sparse, moderately long, semi-erect setae; genae short, about 0.25× as long as greatest length of right eye. Clypeus transverse, slightly convex, with widely and shallowly concave anterior margin and few, long, setae at posterior margin. Labrum slightly convex, longer than clypeus; with shallowly convex anterior margin and six moderately long setae at posterior margin. Maxillary palpi slender, with 4 palpomeres; palpomere 4 conical, elongate, about 1.7× times as long as wide; palpomere 3 nearly as long as wide, 0.6× as long as palpomere 4, with few long setae apically. Mandibles large, moderately curved. Antennae filiform, slender, sparsely pubescent, moderately long, extending to vicinity of posterior one third of elytral length. Scape widest, subcylindrical, 1.8× as long as wide; pedicel cylindrical, 1.4× as long as wide, nearly as wide as scape; antennomeres 3–10 subcylindrical, subequal in size, 2.2–2.6× as long as wide, distinctly narrower than pedicel; antennomere 11 slightly fusiform, pointed apically, 3.3× as long as wide. Relative length ratios of antennomeres 1–11 equal to 16:11:11:13:15:13:15:15:15:15:20. Distance between antennal sockets nearly equal to diameter of left socket.

Prothorax. Pronotum transverse, 1.5× as wide as long, slightly convex dorsally; widest medially, laterally shallowly convex; pronotal posterior margin distinctly narrower than adjacent region of elytra. Pronotal punctation close and large but shallow. Lateral pronotal margins broadly bordered; posterior margin convex, apparently with narrow bordering; anterior margin almost straight in dorsal view, arcuate in frontal view, without bordering. Posterior pronotal angles obtuse; anterior angles nearly obtuse; anterior and posterior angles with trichobothrium, setae long and erect. Anterolateral callosities large, prominent. Hypomera slightly convex, apparently impunctate. Prosternum slightly convex, with sparse and fine punctation, and row of moderately large punctures at posterior margin; prosternal process about half as wide as transverse diameter of procoxa, with concave lateral margins and convex posterior margin, dilated apically, slightly projecting posterior to procoxae, with narrow carina medially and large coarse punctures either side of this.

Pterothorax. Scutellar shield moderately large, triangular, about 1.4× as wide as long, and impunctate. Elytra weakly convex dorsally, subparallel-sided, slightly narrowed posteriad, widest at middle of elytral length, and narrowly bordered laterally. Elytral strial punctation strong and close, fifth stria deepened at base; distance between punctures in striae about 0.5–1.0× diameter of one puncture; interstriae slightly convex, apparently impunctate, distance between striae about 1–1.5× diameter of one puncture. Elytral apices not separately rounded. Elytral epipleura rather wide, gradually narrowed posteriorly, with row of small punctures at inner lateral margin. Mesoventrite narrow, almost flat, with row of large deep punctures along posterior margin. Metaventrite transverse, about 2.6× as wide as long, convex, shiny, impunctate, with row of large deep punctures along anterior margin; metanepisternum with slightly concave lateral margins, anterior and posterior margins oblique, about 5× as long as wide, with row of moderately large punctures.

Legs moderately long and robust; sparsely covered with fine, recumbent pubescence and very fine punctation. Procoxa widely oval, transverse, 1.6× as wide as long; mesocoxa nearly spherical; metacoxa elongate oval, transverse, very narrowly separated. Pro- and mesofemora slightly flattened and widened medially, mesofemur 2.7× as long as wide; metafemur strongly swollen, about 1.8× as long as wide. Tibiae slightly curved, slightly dilated dis- tally (metatibia strongly dilated distally); pro- and mesotibiae equal in length to pro- and mesofemora respectively, metatibia slightly shorter than metafemur; protibia 0.6× as wide as profemur, without apical spur; mesotibia 0.6× as wide as mesofemur, without apical spur; metatibia robust, about 0.3× as wide as metafemur, with large apical spur and fringe of stout setae apically, with small spines dorsolaterally in apical portion. Pro- and mesotarsi distinctly elongated and dilated. Relative length of mesotarsomeres 1–3 and 5 equal to 5:3:4:4. Metatarsus attached to apex of metatibia; 0.7× as long as metatibia; metatarsomere 1 moderately long, nearly as long as metatarsomeres 2–4 combined, and 2.1× as long as mesotarsomere 1; relative length of metatarsomeres 1–3 and 5 equal to 11:5:4:3.

Abdomen. Ventrites sparsely covered with fine punctures; ventrite 1 distinctly longer than ventrites 2–4 com- bined (medially), with intercoxal process bordered by large deep punctures; ventrite 5 as long as ventrites 3–4 combined, widely lobed medially, with sharp, moderately shallow incision on either side of lobe. Suture between ventrites 1 and 2 convex; suture between ventrites 2 and 3 almost straight; sutures between ventrites 3–5 concave. Relative median length ratio of ventrites 1–5 equal to 25:7:6:6:12.

Median lobe of aedeagus ( Figs. 14–17 ) nearly parallel-sided, laterally strongly ribbed, lanceolate in apical portion, with sharp, triangular, flattened apex; with wide, V-shaped, longitudinal groove ventrally; in lateral view, almost straight, thin in apical fifth, moderately wide mesally and basally.

Etymology. The specific epithet refers to the apparent similarity of this species with members of the flea beetle genus Batophila .

Figures

FIGURES 1–3. Photomicrographs of Groehnaltica batophiloides holotype, C 7806 [GPIH]: 1—habitus, left lateral view; 2— habitus right lateral view; 3—right metatibia and metatarsus, lateral view. Scale bars represent: 0.4 mm for Figs. 1 and 2; 0.2 mm for Fig. 3.

FIGURES 4–7. X-ray μCT renderings of Groehnaltica batophiloides holotype, C 7806 [GPIH], habitus: 4—right lateral view; 5—dorsal view; 6—left lateral view; 7—caudal view. Scale bar represents 0.4 mm.

FIGURES 8–9. X-ray μCT renderings of Groehnaltica batophiloides holotype, C 7806 [GPIH], habitus: 8—ventral view; 9—ventral view without legs, showing details of thorax and abdomen. Scale bar represents 0.4 mm.

FIGURES 10–13. X-ray μCT renderings of Groehnaltica batophiloides holotype, C 7806 [GPIH], details of head and prothorax: 10—dorsal view; 11—ventral view; 12—frontal view; 13—right lateral view.Abbreviations: as—antennal socket, c—clypeus, fcl—postantennal callus, fcr—frontoclypeal carina, la—labrum, m—mandible, mp3–mp4—maxillary palpomeres 3 and 4 respectively, o—orbit, os—orbital sulcus, p—prosternal intercoxal process, pc—procoxa, scs—supracallar sulcus, sos—supraorbital sulcus. Scale bar represents 0.4 mm.

FIGURES 14–17. X-ray μCT renderings of Groehnaltica batophiloides holotype, C 7806 [GPIH], aedeagus: 14—dorsal view; 15—ventral view; 16—lateral view; 17—ventro-lateral view.