Pseudosencera baltica, Makarkin & Wedmann & Weiterschan, 2018

Makarkin, Vladimir, Wedmann, Sonja & Weiterschan, Thomas, 2018, The first green lacewings from the late Eocene Baltic amber, Acta Palaeontologica Polonica 63 (3), pp. 527-537 : 529-531

Pseudosencera baltica sp. nov.

Figs. 2–4 .

Etymology: In reference to Baltic amber.

Holotype: SMF-Be-2518; an incompletely preserved specimen.

Type locality: Baltic amber (precise collecting locality unknown). Type horizon: Late Eocene.

Diagnosis.—Antennal flagellomeres with 5‒6 rings of setae. In forewing, RA relatively short, entering margin far before wing apex; basal subcostal crossvein (1scp-r) located far proximad origin of RP; single distal subcostal crossvein; apparent intramedian cell absent; Psm well developed, straight; Psc well developed, slightly zigzagged; AA1 simple; basal crossvein 1m-cu short; distal crossvein 2icu very long. In hind wing, MA fused with RP proximally; Psm well developed, straight; CuA partially fused with MP.

Description.— Head: vertex not elevated; eyes large; ventral border of clypeus slightly concave. Frontal sutures and epistomal suture well developed. Anterior margin of labrum deeply concave. Galea enlarged (long, broad) with short digitus (finger-like apical process). Maxillary palpus five-segmented: two basal segments appear short; third to fifth (terminal) segments elongate (relative length of third to fifth segments: 1.5–1–2.4); terminal segment longest, fusiform. Labial palpus three-segmented; all segments elongate, terminal segment fusiform. Antennae incompletely preserved: scapus rather broad, but short; pedicellus elongate (ca. 1.4 as long as wide), probably very slightly constricted medially (poorly visible); proximal flagellomeres elongate, each probably with 5‒6 rings of setae (difficult to count).

Details of thorax not clearly discernible; pronotum dorsally covered with rare long setae. Forelegs and mid-legs shorter than hind legs; all legs covered (especially femur and tibia) with dense, relatively long, fine setae.

Abdomen: complete, but poorly preserved.

Forewing: 13.2 mm long, 4.6 mm wide (length/width ratio 2.9). Costal space moderately broad for most part, basally and apically narrowed; with simple subcostal veinlets relatively widely spaced, and closely spaced apically. ScP relatively short, entering margin far before wing apex. Subcostal space moderately broad; proximal subcostal crossvein (1scp-r) located very basally, nearly at mid-way from wing base to origin of RP; only one distal crossvein in area of pterostigma detected. Tympanum on basal portion of R not detectable with confidence. RA relatively short, entering margin before wing apex, with 4‒5 short, simple distal branches. Origin of RP located relatively close to wing base (at 0.18 of complete length), slightly proximad 2m-cu. Length of RP proximad 1r-m and 1r-m nearly equal. RA space (between RA and RP) relatively narrow, with 13 crossveins. RP strongly zigzagged, with 12 branches, four of them entering Psm; two distal-most branches simple, other branches forked. Basal crossvein 1r-m long, inclined at acute angle to M, connecting RP, M slightly distad fork of M. M appears to originate from R near wing base; forked at nearly a right angle and at level of origin of RP. Apparent intramedian cell absent (actually, it is formally represented by a square formed by the basal crossvein-like part of MP, the proximal part of MP+CuA, the crossvein 1im and the proximal part of MA, see below for details). MA proximally fused with RP1; distally (distad Psc) with two simple branches (left wing) or once forked branches (right wing). MP basally crossvein-like, then fused with CuA; distally (distad Psc) with two simple branches (left wing) or one simple, one forked branch (right wing). Psm well developed, nearly straight. Psc well developed, slightly zigzagged distally. Basal crossvein 1m-cu (“M5”) short, located opposite origin of CuP; 2m-cu absent. CuA partially fused with MP, probably with three long simple branches. CuP once forked, with widely-spaced branches (anterior branch more than twice longer than posterior branch). Two intracubital crossveins: 1icu long, located far proximad basal part of MP; 2icu very long, located distad posterior branch of CuP fork; length of CuP from 2icu to fork nearly equal to branch of CuP fork. Crossvein between CuP, AA1 very short. All anal veins short, simple; AA1 arched; AA2 incurved proximad 1aa1-aa2, arched after; AA3 incurved proximad 1aa2-aa3, nearly straight after. Two crossveins between anal veins: 1aa1-aa2 rather short; 1aa2-aa3 long. Two complete gradate series of crossveins, slightly divergent distally; 8 crossveins in inner series anterior to Psm; 10 crossveins in outer series anterior to Psc (i.e., RP3). Wing membrane apparently hyaline throughout.

Hind wing: markedly narrower than forewing; 11.0 mm long as preserved (estimated complete length ca. 11.8‒12.0 mm), ca. 3.1 mm wide. Costal space narrow, with simple subcostal veinlets relatively widely spaced before pterostigmal region (basally relatively closely spaced). Termination of ScP, RA not preserved. Subcostal space narrow; subcostal crossveins not detected. RP originates relatively near wing base, strongly zigzagged, with 11 preserved branches, four of them entering Psm. Psm well developed, straight. M basally not fused with R, forked slightly distad origin of RP. MA basally crossvein-like (oblique), then fused with RP for considerable distance; probably simple. MP probably simple. Psc well developed, slightly zigzagged. CuA fused with MP for some distance; one preserved branch (CuA1) originated before fusion with MP. Two gradate series of crossveins (incompletely preserved).

Remarks. —A chrysopid specimen figured by Weitschat and Wichard (1998: pl. 55d) appears to be conspecific with Pseudosencera baltica gen. et sp. nov. as its venation is nearly identical with that of the holotype. This specimen was previously treated as probably belonging to Belonopterygini (a tribe of Chrysopinae ) by Makarkin and Archibald (2013) and Archibald et al. (2014), but the phylogenetic relationships of Pseudosencera baltica gen. et sp. nov. are obscure, what is discussed below. Its antennae (if they are completely preserved, what is rather likely) are markedly shorter than the forewing (nearly two-thirds).

Stratigraphic and geographic range.— Late Eocene Baltic amber.

Figures

Fig. 2. Green lacewing Pseudosencera baltica gen. et sp. nov.from the late Eocene Baltic amber.Holotype (SMF-Be-2518) in dorsal (A) and lateral (B) views.

Fig.3. Green lacewing Pseudosencera baltica gen.et sp. nov.from the late Eocene Baltic amber.Head and legs of the holotype SMF-Be-2518.A. Photograph, fronto-lateral view. B. Line drawing of the head, latero-frontal view. Abbreviations: ant, antenna; ept, epistomal suture; fs, frontal suture; ga, galea; lbr, labrum; lp, labial palpus; mp, maxillary palpus; mtfe, metafemur; mtti, metatibia; pe, pedicellus; pfe, profemur; pti, protibia; sc, scapus; vt, vertex.

Fig. 4. Green lacewing Pseudosencera baltica gen. et sp. nov. from the late Eocene Baltic amber. Wing venation of the holotype SMF-Be-2518, right (A) and left (B) forewing, left hind wing (C). B, C converted to right dorsal view. Abbreviations: 1aa1-aa2, first crossvein between AA1 and AA2; 1aa2-aa3, first crossvein between AA2 and AA3; 1icu, first (basal) crossvein between CuA and CuP; 2icu, second crossvein between CuA and CuP; 1cu-aa, fist crossvein between CuP and AA1; 1im, first crossvein between MA and MP; 1m-cu, first (basal) crossvein between M and Cu; AA1–3, first to third anterior analis; CuA, anterior cubitus; CuA1, first (proximal-most) branch of CuA; CuP, posterior cubitus; M, media; MA and MP, anterior and posterior branches of the media; Psc, pseudocubitus; Psm, pseudomedia; RA, anterior radius; RP, posterior radius; RP1–5, first (proximal-most) to fifth branches of RP; ScP, posterior subcosta.