Bittacopsocus megacephalus Beutel, Prokop, Müller et Pohl, 2019

Beutel, Rolf Georg, Prokop, Jakub, Müller, Patrick & Pohl, Hans, 2019, † Bittacopsocus- a new bizarre genus of † Permopsocida (Insecta) from Burmese Cretaceous amber, Zootaxa 4576 (2), pp. 357-366 : 358-364

† Bittacopsocus megacephalus Beutel, Prokop, Müller et Pohl sp. nov.

Material examined. Currently only one nearly complete specimen is known (No. BUB2853). The winged adult designated as the holotype of the new species is housed in the collection of Patrick Müller (66894 Käshofen, Friedhofstrasse 9, Germany). The specimen will be made freely available upon request.

Etymology. The genus name “ Bittacopsocus ” refers to the habitus resembling the mecopteran hanging flies ( Bittacidae ), combined with “psocus” referring to the resemblance with Psocoptera (barklice) (Greek “psōchos” = dust). The species epithet refers to the large relative size of the head (Greek “mega” = large, “cephalon” = head).

Diagnosis. In the case of the fossil described here, it is not possible to assign a specific diagnosis to species and genus. Consequently, we provide only a single diagnosis. Parts of this can be assigned to a particular rank when further related new taxa will be discovered and described.

The new species can be recognized by the following combination of characters: body small, total length excluding legs ca. 2.5 mm; head semi-prognathous and flattened, very large, in relation to total body size, about as large as thoracic segments combined; mouthparts with elongate mandibles with strongly developed molar plate and long incisors; antennae extremely thin and seven-segmented; transverse crest present on vertex; pronotum with thin collar-like differentiation; pterothoracic segments subequal in size, mesothorax slightly larger; legs extremely elongated and thin, with four-segmented tarsi; wings very slender, forewings slightly larger, with distinct pterostigmata and two series of pentagonal, hexagonal and heptagonal cells delimited by crossveins; ScP connected to costa over short distance close to wing base, then diverging posteriorly towards radius; M + CuA basally attached to R; long fusion of veins M and CuA with successively diverging CuA1 and CuA2 enclosing a narrow, almost triangular cell, the areola postica; long crossvein cua-cup with alternating polarity from proximally convex to distally concave; anal area formed by two stiffened anal veins; A1 with numerous strong spines; forewing with three branches of RP and six main branches of M; hindwing with two branches of RP and four branches of M; abdomen slightly narrowed anteriorly, widest in middle region, apparently neither compressed dorsoventrally nor laterally; segmental borders distinctly recognizable in middle region; posteriorly with moderately enlarged last exposed sternum and small appendages, likely parameres.

Remarks. We assume that the specimen is a male as otherwise an exposed ovipositor (gonapophyses VIII and IX [=1 st and 2 nd valve], as shown in Liang et al. 2016: fig. 2B) should be recognizable.

Description (adult male). Habitus ( Figs 1 , 2 )

With very large head and relatively compact postcephalic body. Length from anterior cephalic margin to abdominal apex ca. 2.5 mm, but legs much longer. Only few long setae recognizable but some regions like antennae, legs, outer margin of wings and posterior abdominal sternites with dense vestiture of short hairs. Coloration light brown, probably due to taphonomy.

Head ( Figs 3A, B ) semi-prognathous, moderately inclined, flattened. Large in relation to size of postcephalic body, head capsule longer than thoracic segments combined. Foramen occipitale large, neck region broadly connected with prothorax by exposed cervical membrane. Ventral closure of head well sclerotized, probably formed by gula, with dense pattern of distinct punctures. Coronal suture present, originates at anterior border of transverse crest, extends to middle region of compound eyes; other ecdysial sutures not recognizable, apparently absent. Compound eyes well-developed, with numerous ommatidia, oval, moderately flattened dorsoventrally, separated from ventral region of head capsule by distinct lateral edge. Median ocellus located between antennal insertion areas, paired ocelli present between middle region of compound eyes. Region of vertex with conspicuously raised transverse crest, continuous with lateral sub-ocular edge. Clypeus divided in longer postclypeus and shorter transverse anteclypeus; paraclypeal lobes (see Huang et al. 2016: fig. 2g) absent; postclypeus only very slightly convex; frontoclypeal and clypeolabral suture distinct, transverse. Right anterior tentorial pit recognizable at proximolateral edge of frontoclypeal suture. Free labrum well-developed, large, with curved, short setae on surface and longer setae along anterior edge. Antennal insertion areas located antero-dorsad anterior margin of compound eyes, widely separated. Scapus very large, slightly shorter than compound eyes, slightly narrowing proximad, then again widened at base; surface with indistinct pattern of short setae; pedicellus less than half as long as scapus and distinctly narrower, with oblique distal edge; pattern of setae similar to that of scapus; flagellum thin and very long, composed of only five segments, with dense pattern of spine-like setae; two first flagellomeres subequal in length, 2 slightly longer than 1; flagellomeres 3 and 4 almost equal in length, each slightly longer than 2; apical segment two-thirds the length of flagellomere 4, even thinner than proximal flagellomeres. Mandibles well-developed, long, slightly intercrossing in midline, with long incisors. Proximal maxillary parts not clearly recognizable, endite lobes not visible; maxillary palp slender, four-segmented, normally developed. Prementum very distinctly separated from proximal labial elements; labial endite lobes not recognizable; labial palp unmodified, slender, probably three-segmented, but proximal palpomere not clearly recognizable; apical palpomere spindle-shaped.

Thorax ( Figs 2 , 3A , 4 , 5 ) slightly longer than head. Cervical sclerites not recognizable, apparently absent. Pronotum anteriorly with thin-walled elevated ridge forming dorsal collar-like structure; posterior pronotal subunits present as two transverse bulges, anterior one with strong lateral seta. Pleural region with very distinct oblique line, probably representing propleural suture, ventrally reaching proximal procoxal margin. Precoxal sternal region sclerotized, well-developed, as wide as entire segment, about as long as procoxal base; profurcal or prospinal pits not recognizable. Procoxae medially adjacent, conical, about 1.5 as long as wide at base. Protrochantin not recognizable. Short protrochanter distinct, with group of pointed, anteriorly directed spine-like setae. Femur cylindrical, thin and elongated, about as long as head and thorax combined, slightly widening distally; surface with dense vestiture of short, spine-like setae. Tibia approximately 1.5 times as long as femur, distinctly thinner, smallest diameter in middle region; vestiture similar to that of femur; single stout tibial spur visible. Tarsus thin and four-segmented, without euplantulae or hairy soles; tarsomere 1 much longer than others, with similar vestiture as femur and tibia; tarsomere 2 about 1/3, 3 about half as long 2; distal segment longer than penultimate tarsomere, distinctly widening distally, with claw and arolium.

Both pterothoracic segments larger than prothorax, mesothorax slightly larger than metathorax. Mid legs similar to prolegs, but medially adjacent coxae more elongated, and hind legs distinctly longer than other two pairs. Details of meso- and metanotum and pleural regions not visible. Mesoventrite extensive, metaventrite much smaller.

Two pairs of wings well-developed but narrow, with distinctly reduced anal field; pterostigma distinct, black, larger on hind wing. Forewing length 4.68 mm, maximum width 0.94 mm. Hind wings slightly shorter and narrower than fore wings, with fewer terminal branches of M. Row of distinct spines present at antero-basal edge, and also possible stridulatory organ close to wing base; entire margin of both wings with seam of fine long setae. Wing venation strongly affected by extremely narrow base, with a long stem of M + CuA; long part of anterior margin formed by C + Sc + RA; short branches of CuA1 and CuA2 diverge successively from M.

Forewing venation with two series of closed pentagonal, hexagonal and heptagonal cells; ScP basally connected to costa over short distance, then diverging obliquely towards radius 0.63 mm distad of wing base; division of RA and RP 0.97 mm from wing base; convex RA continues anteriad to connect with C + ScP towards wing apex; three short crossveins present between RA and RP short of the pterostigma; RP distally connected to anterior branch of M, ending with three branches, two of them directed anteriad and parallel, covering wing apex; pterostigma well developed, with distal limit 0.42 mm from wing apex; crossvein perpendicular to RA and to RP exactly below middle of pterostigma; M+CuA diverges posteriad from stem of R 1.77 mm from wing base; short posterior branches of CuA1 and CuA2 diverge successively from M forming areola postica as long and almost triangular cell; M deeply bifurcated shortly behind branch of CuA2; anterior branch zigzag-shaped, ending on posterior wing margin approximately at level of pterostigma; posterior branch also zigzag-shaped, with five main short posterior branches ending on posterior wing margin; long crossvein cua-cup present with alternating polarity from proximally convex to distally concave; division of CuA and CuP very close to wing base; slightly concave and faint CuP running nearly straight closely parallel to crossvein cua-cup towards posterior wing margin; two convex and reinforced anal veins A1 and A2 diverge 0.24 mm from wing base; A1 with numerous strong spines.

Hindwings similar to forewings in shape and general venation pattern, but slightly smaller and differing in several specific features: only one large closed cell present, located in distal 3 rd of wing; proximal rows of spines absent; ScP approaching costal margin close to wing base, afterwards connected with it over distance of 0.10 mm, then diverging posteriad towards radius; RP ending with two branches at wing apex; M pectinate with four short posterior branches ending on posterior wing margin.

Abdomen ( Fig. 6 ) probably composed of eight distinctly developed segments, but proximal segments not clearly visible. Anterior segments moderately narrowed but without distinct constriction. Presumptive segments III–VII distinctly separated, with distinctly developed tergites and sternites of similar length. Tergites and sternites not overlapping. Presumptive sternite VIII elongated, forming subgenital plate; tergite VIII shorter but apparently strongly sclerotized. Paired processes, presumably parameres of aedeagus, recognizable between tergite and sternite VIII. Paraproct indistinctly visible on one side. Spiracles not recognizable.

Figures

FIGURE 1. A, B, Microphotograph, †Bittacopsocus megacephalus, from both sides.

FIGURE 2. †B. megacephalus, line drawing. Abbreviations: ab—abdomen, cx—coxa, fe—femur, fl—flagellomere, pedpedicellus, prn—pronotum, sc—scapus, ta—tarsomere, tr—trochanter.

FIGURE 3. †B. megacephalus, line drawings, A, head, dorsolateral view; B, ventrolateral view. Abbreviations: aclanteclypeus, atp—anterior tentorial pit, ce—compound eye, col—collar, cor—coronal suture, cre—transverse crest, cx—coxa, ga—galea, lbr—labrum, md—mandible, oc—ocellus, pcl—postclypeus, ped—pedicellus, pl—labial palp, pmx—maxillary palp, sc—scapus.

FIGURE 4. †B. megacephalus, wings. Abbreviations: Ap—areola postica, C—costa, CuA—cubitus anterior, M—media, RA—radius anterior, RP—radius posterior, ScP—subcosta posterior.

FIGURE 5. †B. megacephalus, wing bases. A, forewing; B, hindwing. Abbreviations: A1, A2—anal veins, Ap—areola postica, CuA-CuP specialized crossvein, CuA—cubitus anterior, M—media, RA—radius anterior, RP—radius posterior, ScP—subcosta posterior.

FIGURE 6. †B. megacephalus, abdomen. A, entire abdomen, right side; B, posterior abdomen, left side. Abbreviations: parparamere, prp—paraproct, sVIII—sternum VIII.