Paraphloeostiba morosa 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

† Paraphloeostiba morosa Shavrin & Yamamoto sp. nov. Figures 5, 6, 45-46, 47, 48, 49-53

Type materials examined.

Holotype (female), FMNHINS-3260632, complete specimen as inclusion in a piece of small yellow Baltic amber, 15.6 mm × 13.1 mm × 4.0 mm in size (Figs 5, 6), with the following labels: "14[printed] 11[handwritten]- SYAC 00 [printed]06 [handwritten] | Baltic / Burmite | Other: | Larva / Adult | Omaliinae [handwritten] | Kalini[n]grad [handwritten] | Shûhei Yamamoto’s | Amber Collection" <large rectangular label, printed>, "Kaliningrad, RUSSIA | Shûhei Yamamoto’s | Amber Collection | (SYAC0006)" <small rectangular label, printed>, "[FMNH barcode at left side of label] FMNHINS | 3260632 | AMBER [handwritten] | FIELD MUSEUM | Wet" <small rectangular label, printed>, "HOLOTYPE | Paraphloeostiba | morosa sp. nov. | Shavrin A. & Yamamoto S. des. 2019" <red rectangular label, printed> (FMNH).

Preservation.

The specimen is located at an angle with the head somewhat deeper in the amber piece (Figs 5, 6); the specimen is clearly visible from both dorsal and ventral sides. Syninclusions: round and elongate air bubbles near the specimen on from the ventral side of its body, and elongate piece of plant material located close to the dorsal surface of amber piece near the beetle.

Locality and horizon.

Baltic amber from Yantarny, Kaliningrad, westernmost Russia; mid-Eocene (ca 44 Ma; Wappler 2005).

Description.

Measurements: HW: 0.36; HL: 0.29; OL: 0.17; AL: 0.51; PML × PMW (III, IV): III: 0.03 × 0.03, IV: 0.06 × 0.02; PL: 0.31; PW: 0.74; ESL: 0.52; EW: 0.77; MTbL: 0.38; MTrL: 0.15 ( I–IV: 0.07; V: 0.08); AW: 0.75; TL: ~1.80. Antennomeres with lengths × widths: 1: 0.07 × 0.03; 2: 0.05 × 0.02; 3: 0.05 × 0.01; 4: 0.03 × 0.02; 5: 0.04 × 0.02; 6-7: 0.03 × 0.03; 8: 0.03 × 0.04; 9-10: 0.04 × 0.05; 11: 0.10 × 0.05.

Body moderately wide, glossy (Fig. 45), black, with mouthparts, femora, and apical parts of abdominal tergites reddish-brown, and tarsi yellow-brown. Body laterally as in Figures 47 and 48. Body without visible microsculpture and setation except of paratergites and abdominal tergite VIII with long erect setae (Fig. 48).

Head 1.2 times as wide as long, with slightly convex posterior portion, dense and small punctation and postocular carina (Fig. 49). Head laterally as in Figure 49, anteroventrally as in Figure 50, and ventrally as in Figure 51. Eyes large, with medium-sized facets, broadly convex, with distinct infraorbital carina (Figs 49-51). Ocelli moderately large, situated at level of posterior third of eyes, distance between ocelli about twice as long as distance between ocellus and medial margin of eye (Fig. 45). Labrum with widely rounded apical margin (Figs 46, 51). Apical maxillary palpomere distinctly longer and slightly narrower than penultimate, swollen in middle and elongate, from middle gradually narrowing toward rounded apex (Figs 49-51). Submentum large, trapezoidal; apical labial palpomere elongate, from middle narrowing apicad (Fig. 49). Gular sutures with markedly rounded posterior parts widely separated from each other below level of posterior margins of eyes (Figs 50, 51). Gena with rugose isodiametric microsculpture (Figs 50, 51). Antenna moderately short, exceeding basal portion of pronotum, with sparse elongate setation; basal antennomere swollen, more than twice as long as wide, antennomere 2 elongate, slightly widened apicad, 3 thin, as long as 2, 4, and 5 markedly widened apicad, 6 and 7 as long as wide, 8-10 slightly transverse, apical antennomere wide, from apical third slightly narrowing toward rounded apex (Figs 45-49).

Pronotum with slightly convex surface, markedly transverse, more than twice longer than broad, twice wider than head, from middle slightly more narrowed anterad than posterad, with widely rounded anterior and scarcely rounded posterior angles; apical margin widely rounded, distinctly shorter than somewhat concave posterior margin; paramedian longitudinal impressions indistinct, wide and long, occupying most of middle portion; lateral margins narrowly emarginate, with indistinctly concave laterobasal margins; posterior angles without depressions (Fig. 45). Dorsal surface of pronotum with more or less regular small and dense punctation, distinctly denser than in posterior portion of head (Fig. 45). Prosternum with widely open procoxal fissures, exposing trochantins, and very long intercoxal process, with acute apex reaching apical part of procoxae (Figs 46, 51). Median part of mesoventrite somewhat convex, with very long acute intercoxal process, reaching more than halfway along the length of the mesocoxae and moderately wide apex of metaventral process (Fig. 46). Scutellum large and triangular, with rounded apex and dense punctation in apical part (Fig. 45). Metaventrite with moderately wide metacoxal cavities (Fig. 46). Median part of prosternum and metaventrite with indistinct and sparse small punctures; mesanepisternum with diagonal microsculpture; median portions of prosternum and metaventrite, including intercoxal processes, with transverse meshes (Fig. 46).

Elytra evidently flattened, 1.4 times as wide as long, 1.6 times as long as pronotum, with moderately parallel lateral sides (Fig. 45), with widely rounded apical angles (Fig. 52), reaching apical margin of abdominal tergite III, with apical margins slightly oblique toward suture (Fig. 45). Punctation as that in pronotum, slightly sparser in basal portion and near scutellum.

Legs moderately long and slender, with wide femora and slender tibiae, gradually widened apicad, covered by elongate setae on both inner and outer margins and with a few strong setae on outer margins (Figs 46-48); tarsi short, with small setae on tarsomeres 1-4, apical metatarsomere slightly longer than preceding tarsomeres together; tarsal claws simple, widely curved and elongate (Figs 46, 53).

Abdomen convex, slightly narrower than elytra, with wide brick-wall sculpture on intersegmental membranes between tergites III–VI (Fig. 52) and sternites III–VI (Fig. 45). Abdominal tergites with moderately dense and deep small punctation and distinct net-like microsculpture (Fig. 52); abdominal sternites with indistinct sparse punctation, with shallow isodiametric microsculpture (Figs 45, 52).

Male unknown.

Female. Apical margin of abdominal tergite VIII rounded. Apical margin of abdominal sternite VIII broadly concave (Fig. 53). Genital segment with moderately wide apical portions of gonocoxites; shape and length of styli invisible, each with very long seta (Figs 47, 48).

Etymology.

The specific epithet is the Latin adjective morosus, -a, -um (strange). It refers to somewhat broad body with markedly transverse pronotum of the new species.

Remarks.

Based on the shape of body and maxillary palpomeres (see also Zanetti 2012: fig. 55l), slightly convex pronotum, punctation and microsculpture of the surface of body, the fossil presumably belongs to the genus Paraphloeostiba . The genus was erected by Steel (1960a) and was compared with Phloeostiba Thomson, 1858 and Phloeonomus Heer, 1839. It differs from Phloeostiba by the shape of short maxillary palpomere 3 and relatively elongate apical palpomere, and from Phloeonomus by a different shape of ligula and maxillary palp (for details see Steel 1960a). Paraphloeostiba includes more than 30 species distributed in the Palaearctic, Madagascan, Nearctic, and predominantly in Oriental, Australian, and Oceanic regions ( Steel 1960a; Herman 2001; Shavrin and Smetana 2016; Shavrin 2017b); one species, P. gayandahense (W.J. MacLeay, 1873) is widely adventive around the world to New Zealand, several countries of Europe, and the USA ( Herman 2001). The new species is difficult to compare reliably with known species as these mostly differ by the structure of the aedeagus, and shapes of accessory sclerite and spermatheca. The apical antennomeres of P. morosa sp. nov. are slightly transverse, beginning with antennomere 8 (Figs 48, 49) while other known species have transverse antennomeres beginning with 6 or 7. Based on the punctation and microsculpture of the pronotum and shape of antennomere 10 (Fig. 49), the new species is similar to P. specularis (Bernhauer, 1915), known from New Britain (Bismarck Archipelago of Papua New Guinea) but differs by the somewhat larger and wider body, the absence of laterobasal pronotal depressions, and the more transverse pronotum (Fig. 45). Based on the shape and coloration of the body, similar punctation, pronotum without depressions on basal portions, and somewhat convex mesoventrite, P. morosa sp. nov. is also similar to P. electrica Zanetti et al., 2016, recently described from Baltic amber, from which it differs by the wider body with more transverse pronotum, as well as elongate antennomeres 4-7, and wide apical and penultimate palpomeres.

Paraphloeostiba requires revision due to unclear morphological boundaries between described species and related genera, as well as many undescribed species from the Oriental and Australian regions deposited in institutional and private collections. The new species is tentatively attributed to this genus, making it the second extinct representative of the genus after P. electrica .