Baltiomiris Kim, Chérot & Jung, 2021

Kim, Junggon, Chérot, Frédéric & Jung, Sunghoon, 2021, A new genus and species of the subfamily Mirinae (Hemiptera: Cimicomorpha: Miridae) from Eocene Baltic amber with a new generic combination for Calocoris antennatus Statz in Statz & Wagner, 1950, Zootaxa 5057 (4), pp. 571-576 : 572-574

Genus Baltiomiris Kim, Chérot & Jung gen. nov.

( Fig. 1 )

Diagnosis: Differs from other extinct genera in the subfamily Mirinae by an elongate body, moderate in size approximately 5 mm; vertex carinate, not sulcate, slightly wider than single compound eye; antennae long, total length longer than body; third antennal segment much longer than first segment; apex of labium reaching hind coxae; pronotum with relatively wide but shallow punctures, densely covered with short pubescence; pronotal collar longer than first antennal segment diameter; hemelytra with small shallow punctures, densely covered with short pubescence; cuneus elongate; hind femur exceeding apex of abdomen; and last tarsal segment longest.

Description: Male: Body elongate, moderate in size, partly punctate, covered with one type of setae, bristleshaped, round in cross section, semi-erect; head prognathous, projected dorsally, wider than long; vertex carinate, not sulcate, slightly wider than compound eye, as wide as first antennal segment length, with tufts of setae; ventral margin of compound eye reaching maxillary plate suture; antennae cylindrical, total length longer than body, covered with short pubescence; first segment thickest; second segment slightly thicker than third segment; third segment much longer than first but shorter than second segment; apex of labium reaching hind coxae; labrum short, shorter than ½ first labial segment; pronotum trapezoidal, longitudinal pronotal length more than ½ posterior width, lateral margin straight, posterior margin concave, densely covered with bristle-shaped setae; pronotal collar width thicker than first antennal segment maximal width; callosities area indistinctly swollen; scutellum flat, wider than long, impunctate; hemelytra densely covered with bristle-shaped setae, partly punctate, lateral margin slightly rounded; commissure length longer than scutellum length; corium punctate along embolio-corial suture (see arrow in Fig. 1a ); cuneus elongate; leg long; hind femur apex exceeding apex of abdomen; tibiae with rows of spine; third tarsal segment longest; claws with pulvilli ( Fig. 1G ); abdomen short, not reaching apex of cuneus.

Type species: Baltiomiris herczeki sp. nov. (fossil) by original designation.

Etymology: Named after combination of ‘ Baltic ’ and ‘ miris ’ the type genus of the subfamily Mirinae , referring to the mirine group from the Baltic amber; gender masculine.

Discussion: By the habitus, particularly the global body shape, the head structure, the presence of pronotal collar, the presence of pulvilli and the shape of parameres, the new plant bug described in the present work could belong to subfamily Mirinae , tribe Mirini ; the subfamilies Bryocorinae , Cylapinae and Isometopinae seeming excluded. Indeed, the head (see Figs. 1D, 1E ) devoid of ocelli, not vertical and not flattened antero-posteriorly differs from Isometopinae highly modified cephalic morphology. The short claws with pulvilli (arrow in Fig. 1G ) differ from Cylapinae and Bryocorinae claws. Unfortunately, the presence and structure (including their eventual orientation) of parempodia could not be confirmed, however based on the provided documentation, placement of the new genus in the other subfamilies is unlikely.

Within the Mirini only two monospecific genera, Mixocapsus Herczek, 1991 and Stenoptera Herczek & Popov, 2009 , are described from Eocene Baltic amber ( Schuh & Weirauch 2020).

Mixocapsus eocenicus Herczek, 1991 was described from a Baltic amber inclusion of apparently unknown origin ( Herczek 1991) and is easily separated from B. herczeki sp. nov. by the vertex not being carinate, and by the claw structure. Mixocapsus eocenicus claws bear a wide “outgrowth”, maybe a pulvillus (see Fig. 2 in Herczek (1991) for this structure); small pulvilli are present in B. herczeki sp. nov. however, they are obviously more reduced, and in M. eocenicus they are phyline-like, to such extent than classification of this taxon in Mirini remains debatable. The two taxa are further separated by the pronotal collar length (shorter than first antennal segment maximal diameter in M. eocenicus , longer in B. herczeki sp. nov.) and by the wide and protruding veins on clavus and corium of M. eocenicus .

Stenoptera sambiensis Herczek & Popov, 2009 was described from a Baltic amber inclusion of the Kaliningrad region ( Herczek & Popov 2009). It is a larger plant bug than B. herczeki sp. nov. (total length about 10 mm versus 5.2 mm), with a longer labium (reaching beyond half of abdominal length versus reaching hind coxae in B. herczeki sp. nov.) and a proportionally longer and thicker first tarsal segment (first tarsal segment is longest and thickest in S. sambiensis , and shorter and thinner in B. herczeki sp. nov.).

Stomatomiris funebris Maldonado & Poinar, 1995 was described from an upper Oligocene to upper Eocene Dominican amber inclusion, and differs obviously from B. herczeki sp. nov. by its habitus, particularly its dorsal pattern (black with anterior part of embolium, a wide spot on the cuneus and some lines on corium and scutellum stramineous versus brown in B. herczeki ), by its vertical head, short in lateral view, with globular eyes, particularly wide and high, by its very narrow vertex, by its longer labium and by the presence of globular ostioles on the three thoracic pleurae with corresponding evaporative area, a totally unique character state in the Miridae .

Remarks: Maldonado & Poinar (1995: 282) use the specific name “ lugubris ” in the caption of their figs 1–7 and the name “ funebris ” two times in the text (to designate the type-species of the genus Stomatomiris , p. 281, first column and to introduce the description of their new Stomatomiris species , p. 282, first column). We consider “ lugubris ” as a lapsus calami and we consequently use the name funebris to designate their species, as the former authors, for example Schuh & Weirauch (2020).

Calocoris antennatus Statz in Statz & Wagner, 1950 was described on a relatively well-preserved compression fossil from an Upper Oligocene formation of Germany (Roth) by Statz & Wagner (1950). This more recent plant bug differs from B. herczeki sp. nov. by its larger total size (total length = 8.2 mm versus 5.2 mm), by its wider hind femora and by its antennal shape, particularly by the amazingly wide first antennal segment comparatively to the size of the diatone (head width across eyes), widened from base to apex, and the club-like second antennal segment (see Statz & Wagner’s photos, op. cit., Taf. XXI, Fig. 4, and Taf. XXIV, Fig. 18).

Here we debate the attribution of the Statz’ and Wagner’s species to the recent genus Calocoris Fieber. The modern concept of Calocoris resulting from Rosenzweig’s works (1997, 2001) differs from Wagner’s concept and “ Calocoris ” antennatus is very unusual for a Calocoris even as defined by Wagner (for example, 1974). The observed character states of C. antennatus , particularly the antennal, pronotal and hemelytral shapes, but also pronotal and hemelytral markings (if they are not artefacts), could fit to the concept of the (recent) genus Mermitelocerus as defined by Yasunaga & Miyamoto (1991) and Rosenzweig (1997, 2001). We provide a photo of M. annulipes Reuter, 1908 , the type-species of the genus, for comparison ( Fig. 2A ). These structures of the first and second antennal segments are observed only in the genus Mermitelocerus within the so-called Calocoris - complex sensu Rosenzweig (1997) as well as within the taxa related to Calocoris sensu lato in Kim & Jung (2019). Therefore, we herein propose that Calocoris antennatus should be treated as Mermitelocerus antennatus comb. n. ( Figs. 2B–C ).

Lygus (?) oligocenica Statz in Statz & Wagner, 1950, described from the same formation in the same work, is separated from B. herczeki sp. nov. by the globose body shape (proportionally shorter and wider, more rounded in “ L ” oligocenica, whose membership to the genus Lygus in the modern sense of the name itself seems very doubtful).

The combination of a carinate vertex, the relatively elongate body shape, the pilosity and the dorsal punctation observed in B. herczeki is unusual compared to recent mirine plant bugs. Such pilosity and row of punctures along embolio-corial suture are known in Argenis Distant and so-called Hyalopeplini , but B. herczeki sp. nov. differs from the first by the body shape, by the first antennal segment shape (being not narrowed just after the base), and by the pattern of hemelytra (devoid of pruinose areas) and from the members of the later by the carinate vertex.

Consequently, we could not assign our fossil specimen to an already described taxon and now describe it as a new genus Baltiomiris gen. nov. and new species B. herczeki sp. nov. based on the only available specimen.

Figures

FIGURE 1. Baltiomiris herczeki gen. and sp. nov. A: dorsal view; B: ventral view; C: lateral view; D: head and pronotum; E: head in lateral view; F: antenna; G: hind tarsus. Scale bars: A–C: 1 mm; D–G: 0.5 mm.

FIGURE 2. Photo of Mermitelocerus annulipes Reuter, 1908 and drawings of M. antennatus comb. n. A: M. annulipes in dorsal view; B: redrawing of M. antennatus comb. n. based on Statz in Statz & Wagner (1950) fig. 4; C: original reconstruction drawing of M. antennatus comb. n. Scale bars: A–C: 2 mm.