Phyllodrepa icari Shavrin & Yamamoto

Shavrin, Alexey V. & Yamamoto, Shuhei, 2019, Unexpected palaeodiversity of omaliine rove beetles in Eocene Baltic amber (Coleoptera, Staphylinidae, Omaliinae), ZooKeys 863, pp. 35-83 : 35

† Phyllodrepa icari Shavrin & Yamamoto sp. nov. Figures 10, 11, 65-66, 67-72

Type materials examined.

Holotype (female), FMNHINS-3260628, complete specimen as inclusion in small rectangular light yellow Baltic Amber, 19.2 mm × 7.9 mm × 5.1 mm in size (Figs 10, 11), with the following labels: "15[printed]04[handwritten] - SYAC 00[printed]94[handwritten] | Baltic / Burmite | Oher: | Larva / Adult | Omaliinae[handwritten] | Baltic Sea Coast, [handwritten] | close to the Wisla Riv. | Estuary, Poland[handwritten] | Shûhei Yamamoto’s | Amber Collection" <large rectangular label, printed>, Nadewca / Sender: | Artur Michalski" <large light yellow rectangular label, handwritten>, "[FMNH barcode at left side of label] FMNHINS | 3260628 | AMBER [handwritten] | FIELD MUSEUM | Wet" <small rectangular label, printed>, "HOLOTYPE | Phyllodrepa | icari sp. nov. | Shavrin A. & Yamamoto S. des. 2019" <red rectangular label, printed> (FMNH).

Preservation.

The specimen is in relatively good condition and best visible from the dorsal side of the body, except the head and right antennomeres 9-11, and with head visible from the narrow side of the amber piece (Fig. 10). The details of the ventral side of inclusion are not visible except for the apical antennomeres, middle and hind legs, and a part of the mesothoracic segment and abdominal sternites (Figs 66, 69, 72). Syninclusion: imago of small Diptera about 1.20 mm in length.

Locality and horizon.

Baltic amber from Baltic Sea Coast, close to the estuary of Wisła River, Gdańsk, Poland; mid-Eocene (ca 44 Ma; Wappler 2005).

Description.

Measurements: HW: 0.31; HL: 0.18; OL: 0.11; AL: 0.50; PML × PMW (III, IV): III: 0.03 × 0.02, IV: 0.05 × 0.01; PL: 0.25; PW: 0.46; ESL: 0.58; EW: 0.66; MTbL: 0.16; MTrL: 0.11 ( I–IV: 0.05; V: 0.06); AW: 0.66; TL: ~1.80. Antennomeres with lengths × widths: 1: 0.08 × 0.03; 2: 0.05 × 0.02; 3: 0.04 × 0.02; 4-5: 0.03 × 0.02; 6: 0.02 × 0.02; 7: 0.04 × 0.03; 8: 0.04 × 0.04; 9: 0.05 × 0.05; 10: 0.05 × 0.06; 11: 0.07 × 0.06.

In general appearance, body (Fig. 65) and legs as in Ph. daedali sp. nov., reddish-brown, with darker head and pronotum; mouthparts, antennae and legs yellow-brown. Body ventrally as in Figure 66.

Head transverse, 1.7 times as wide as long, with slightly convex median portion (Fig. 67); punctation and postocular carina invisible. Eyes very large and broadly convex (Fig. 67). Ocelli large and convex, situated almost at level of posterior margins of eyes, distance between ocelli about twice as long distance between ocellus and medial margin of eye; grooves in front of ocelli very short and moderately deep (Fig. 67). Labrum wide and transverse, with slightly rounded apical margin (Fig. 67). Apical segment of maxillary palp narrow, narrowing from base toward moderately acute apex, distinctly longer and narrower than swollen penultimate segment (Fig. 67). Antenna moderately long, reaching basal third of elytra; antennomeres 1 and 2 swollen and elongate, 3 with very narrow elongate base, 4-6 ovoid, 7-9 slightly and 10 distinctly transverse, apical antennomere slightly longer than wide, strongly narrowed from about apical third (Figs 65, 68).

Pronotum transverse, 1.8 times as wide as long, 1.4 times as wide as head, from middle more narrowed posterad than anterad, with widely rounded slightly protruding anterior and obtuse posterior angles (Fig. 67); apical margin moderately widely concave, distinctly shorter than posterior margin; lateral margins narrowly marginate and slightly crenulate, more distinct posteriorly; laterobasal portions with indistinct wide impressions (Figs 65, 67). Dorsal surface of pronotum with moderately sparse, large and deep punctation, distinctly sparser in basal and apical portions, with narrow impunctate longitudinal area (Figs 65, 67). Scutellum large, with triangular apex, without punctures or microsculpture (Fig. 65).

Elytra 1.2 times as long as wide, reaching apical margin of abdominal tergite III, slightly widened apicad, with widely rounded apicolateral angles and apical margins truncate at suture (Figs 65, 70). Punctation denser, markedly larger and deeper than that on pronotum, smaller in basal and apical, and sparser in lateral portions. Surface between punctures with dense isodiametric microsculpture.

Tarsi long, with apical tarsomere markedly longer than previous tarsomeres together (Figs 66, 69).

Abdomen slightly convex, as wide as elytra or slightly wider, intersegmental membranes between tergites IV–VII with brick-wall sculpture (Fig. 65). Abdominal tergites with indistinct small and very sparse punctation and microsculpture, and with sparse and short pubescence, wing-folding patches not visible.

Male unknown.

Female. First four mesotarsomeres 1-4 without modified setae (Figs 66, 69). Apical margin of abdominal tergite VIII slightly rounded (Fig. 71). Apical margin of abdominal sternite VIII widely concave (Fig. 72). Genital segment with markedly elongate and wide gonocoxites, with very small narrow styli, each with very long seta (Fig. 72).

Etymology.

The specific epithet is the Latinized name of Icarus (Ikaros), son of Deaedalus in Greek mythology.

Remarks.

Despite the shape of antennomere 3 and the posterior angles of the pronotum, which are usual in members of the genus Acrolocha Thomson, in other external characters (see details above), the new species belongs to the genus Phyllodrepa . The fossil shares with that genus slightly protruded anterior angles of the pronotum with impressed laterobasal portions (Fig. 67), similar to those of extant North European Ph. sahlbergi Luze, in addition to similar coloration of the body and proportions of antennomeres 4 and 5 (Fig. 68). However, the fossil differs from that species by the significantly smaller and slightly more convex body (Fig. 65), with more prominent eyes (Fig. 67), coarser punctation of the elytra and pronotum, pronotum with less sinuate lateral margins (Figs 65, 67), less transverse antennomeres 6-10 (Fig. 68), and longer elytra (Fig. 70). Based on the shape of its small and pale body, and large and deep punctation of the elytra (Figs 65, 70), Ph. icari sp. nov. is similar to Ph. daedali sp. nov., from which it differs by the paler abdomen, narrow apical maxillary palpomere (Fig. 67), the shape of anterior angles of the pronotum protruding apicad, sparser punctation of the pronotum, distinctly transverse head and pronotum (Fig. 67), shorter antennomeres 4, 5, and 11 (Fig. 58), and shorter elytra.