Proneuronema minor, Makarkin, Vladimir N., Wedmann, Sonja & Weiterschan, Thomas, 2016

Makarkin, Vladimir N., Wedmann, Sonja & Weiterschan, Thomas, 2016, A new genus of Hemerobiidae (Neuroptera) from Baltic amber, with a critical review of the Cenozoic Megalomus - like taxa and remarks on the wing venation variability of the family, Zootaxa 4179 (3), pp. 345-370 : 347-352

Proneuronema minor sp. nov.

( Figs. 1–6 )

Diagnosis. May be distinguished from other species by the following characters: crossveins in costal space in forewing absent [at least four costal crossveins in other species]; M only once forked proximad third gradate series [two to three times in other species]; distinct color pattern in forewing absent [present in P. w e hr i; at least a dark band through outer gradate series in P gradatum sp. nov.]; comparatively small size [forewing length 6.3–6.9 mm; 7.9–9.5 mm in P. gradatum sp. nov., 9 mm in P. wehri ].

Description. Holotype GZG.BST.05246 ( Figs 1–3 ). Female. Body length 5.2 mm as preserved. Head cuneiform in lateral view. Eyes relatively large. Vertex slightly elevated. Postocular lobe narrow. Terminal segment of maxillary palps rather broad, without additional subsegment. Antennae: scapus rather large; pedicel markedly larger than proximal flagellomeres; both flagella 40-segmented. Pronotum rather short, covered with dense long setae. Procoxa very long. Metatibia about 1.7 times as long as metafemur, slightly curved and thinner proximally, not especially swollen medially. Two small apical tibial spurs present in each leg.

Abdomen completely visible in left lateral view, but mostly obscured by milky covering. Female terminalia typical for Megalomus -like genera, but indistinctly visible: 7th tergite, 7th sternite long, not specialized; 8th tergite probably rather narrow, extending laterally to 7th sternite; 8th sternite not visible (probably transformed to subgenitale); 9th tergite extending laterally to ventral part of abdomen; ventrally it is strongly dilated; gonocoxite 9 almost entirely hidden, but its gonostylus faintly visible; upper part of 9th tergite and ectoproct almost entirely obscured by milky covering and strange flower-like structure ( Fig. 3 A, ‘?’); probably, this structure does not belong to the body.

Forewing oval with subacute apex, 6.9 mm long, 3.0 mm wide. Trichosors prominent all around wing margin. Costal space very broad, dilated basally (0.8 mm maximum width). Majority of subcostal veinlets branched once or twice. Humeral veinlet recurrent, pectinately branched, with five branches (one to two forked). Presumable ScA distinct. No true crossveins in costal space. Subcostal space moderately wide for entire length, with four crossveins (basal 1scp-r, intermediate 2scp-r, 3scp-r, distal 4scp-r). Posterior trace of RA forked apically, with two distal branches, one of them forked once, the other simple. RA space as wide as subcostal space basally. RP with two (left forewing) or three (right forewing) ORBs. ORB1 with two (right wing) or three (left wing) branches directed anteriorly, originating proximad third gradate series of crossveins. ORB2 (left forewing) simple. ORB3 (left forewing) or ORB2 (right forewing) (RP proper) possesses two (left wing) or three (right wing) branches, originating proximad fourth gradate series. M appears not fused basally with R. M forked proximal to second gradate series; MA, MP parallel before terminal branching. Cu dividing into CuA, CuP close to wing base. CuA pectinately branched, with five branches, all of which have marginal forks. CuP deeply forked, each branch with marginal fork. 1AA deeply forked, anterior branch with two short simple pectinate branches; posterior branch only with marginal fork. 2AA pectinately branched. 3AA probably simple (not clearly visible). Four gradate series of crossveins (series 1–4 of Oswald 1993) posterior to RA. First series consists of four crossveins: 1m-cu, 1icu, 1cu- a1, 1a1-a2; an additional (aberrant) crossvein located distad 1icu (present in right forewing only). Second series includes four crossveins: 2r-m, 2im, 2m-cu, 2icu; an additional (aberrant) crossvein located basad 2icu (present in left forewing only). Third (‘inner’) series with eight crossveins, from 3ra-rp to 3m-cu; 3ra-rp (left forewing) and 2irp (right forewing) aberrantly doubled. Fourth (‘outer’) series complete, with 21 (right forewing) and 19 (left forewing) crossveins, from 4ra-rp to 4cu-a1. All longitudinal veins relatively pale. Membrane slightly fuscous, no pattern.

Hind wing 5.9 mm long as preserved (estimated length 6.1 mm), 2.6 mm wide. Trichosors prominent all around wing margin. Costal space narrow, slightly dilated distally, 31 simple veinlets, one distal-most forked. Humeral lobe triangular. Humeral plate bears long, dense bristles. Only distal subcostal crossvein detected. RA distally with three veinlets (one-two forked). RA space proximally only slightly dilated, narrowest at crossvein 1r1- rs, which is strongly oblique. RP with five (left wing) to six (right wing) branches before outer gradate series, one of them originating before 1ra-rp. Basal sinuous crossvein 1r-m connecting RP1 and M. M forked distad origin of RP1; MA, MP nearly parallel before outer gradate series, then both forked. CuA pectinate, with five branches; proximal-most branch of CuA forked twice; most of other branches with marginal fork. CuP thin, with two short branches (right wing). AA1 pectinate. Second (inner) gradate series includes two crossveins (between RP2, MA); third (outer) series with 10 crossveins (from RA to CuA). One marginal crossvein between CuA, CuP, and one between CuP, AA1. All longitudinal veins relatively pale. Membrane paler than in forewing; no pattern.

Specimen SMF Be 2535 ( Figs 4–6 ). Male. Head cuneiform in lateral view. Eyes relatively large. Postocular lobe narrow. Terminal segment of maxillary palps rather broad, without additional subsegment. Scapus rather large.

Metatibia about 1.5 times as long as metafemur, slightly curved and thinner proximally, markedly swollen medially. Apical tibial spurs small. Male abdominal terminalia: 8th sternite long, unspecialized; 9th tergite narrow, extending laterally almost to 9th sternite; 9th sternite long and rather narrow (boat-like), extending caudally to level of outer margin of ectoproct; ectoproct in general rounded, appears slightly concave ventrally (poorly visible), with long setae and large rounded callus cerci ( Fig. 6 ); outer, ventral margins of ectoproct without visible processes.

Forewing oval with rounded apex, 6.3 mm long, 2.9 mm wide. Trichosors prominent all around wing margin. Costal space very broad, dilated basally. Eight proximal and one distal-most subcostal veinlets forked; 14 distal subcostal veinlets simple. Humeral veinlet recurrent, pectinately branched, with six branches (of these one forked). Presumable ScA short. No crossveins in costal space. Subcostal space moderately broad for entire length, with four crossveins (basal 1scp-r, intermediate 2scp-r, 3scp-r, distal 4scp-r). RA forked apically; its two branches once forked. RA space as wide as subcostal space basally. RP consists of three ORBs. ORB1 twice deeply forked, originating far proximad third gradate series, with branches directed anteriorly. ORB2 simple for most length, distally dichotomously branched. ORB3 (RP proper) originating relatively far from wing base, with three branches originating proximad fourth gradate series in left forewing; second branch rather deeply dichotomously branched. M basally not fused with R, forked distad origin of ORB1. MA, MP parallel before terminal branching. Cu dividing into CuA, CuP close to wing base. CuA pectinately branched, with five forked branches; in right wing, two branches touching each other at their origin, and one other branch deeply forked. CuP rather deeply forked; anterior branch with marginal fork, posterior branch simple. AA1 rather deeply forked; anterior branch with two short simple pectinate branches; posterior branch with marginal fork. AA2 rather deeply forked; each branch with marginal fork (right wing). AA3 short, deeply forked; each branch simple (right wing). Four gradate series of crossveins posterior to RA. First (basal) series consists of three crossveins: 1m-cu, 1cu-aa1, 1aa1-aa2. Second series consists of four crossveins: 2r-m, 2im, 2m-cu, 2icu. Third (‘inner’) series consists of nine crossveins (left wing), from RA to CuA; 3rp1-rp2 aberrantly doubled. Fourth (‘outer’) series complete, with 20 crossveins (left wing), from RA to AA1. No color pattern.

Hind wing 5.0 mm long, 2.2 mm wide as preserved (left wing). Trichosors prominent along all preserved wing margin. Costal space narrow, somewhat dilated distally, with all subcostal veinlets simple. Only one (distal) subcostal crossvein detected. RA distally dichotomously branched. RA space slightly wider than subcostal space; crossvein 1ra-rp not detected in right wing, indistinct in left. Six (right wing) to seven (left wing) branches of RP before outer gradate series. Basal sinuous crossvein 1r-m long, connecting RP1 and M. M forked probably much distad origin of RP1; MA, MP nearly parallel for most length; MA simple (right wing) and with terminal fork (left wing); MP once (left wing) and twice (right wing) forked distally. Cu dividing into CuA, CuP near wing base. CuA pectinate, with four distal branches preserved. CuP, anal veins poorly visible. Second (‘inner’) gradate series consists of three crossveins (from RP3 to MA) in left wing; poorly preserved in right wing (only one clearly visible). Third (‘outer’) with 11 preserved crossveins (from RA to CuA) in right wing, 10 crossveins in left wing (4ra-rp abnormally doubled).

Material. Holotype GZG.BST.05246, deposited in GZG. Old labels: “B[ernstein] S[ammlung] d[er] Univers[itat] Koenigsberg i[n] Pr[eussen].”; N 19”; “5238” “5864”. A complete female specimen (but apical tip of one of the forewings is missing); left body side is obscured by a milky covering.

Specimen No. SMF Be 2535, deposited in SMF (formerly in the private collection of Thomas Weiterschan, coll. No. 1655). An almost complete male specimen (distal part of right forewing is missing); the body is partially obscured by a milky covering.

Type locality and horizon. Baltic amber (the holotype was probably collected near present-day Kaliningrad; precise collecting site of specimen SMF Be 2535 is unknown); late Eocene.

Etymology. From the Latin parvus [- a, - um] (comparative minor ), small (smaller), in reference to its smaller size compared to other species of the genus.

Remarks. These two specimens have a very similar venation (considering its variability) but differ in particular by the shape and relative length of the metatibia. The absence of the crossvein 1ra-rp in the hind wing as found in SMF Be 2535 occurs as an anomaly also in a specimen of M. flinti (see Monserrat 1997: Fig. 104).

The venation of a specimen of Hemerobiidae from Baltic amber (the forewing is about 6 mm long) reported by Erichson & Weitschat (2000: Fig. 45) is similar to that of Proneuronema minor sp. nov. However, its forewing appears darker, and third and fourth gradate series of crossveins appear to be margined with dark brown.

Figures

FIGURE 1. Proneuronema minor gen. et sp. nov., holotype GZG. BST. 05246, lateral view. A, right side. B, left side. Scale bars = 1 mm.

FIGURE 2. Proneuronema minor gen. et sp. nov., wing venation of the holotype GZG. BST. 05246. A, right forewing. B, right hind wing. C, left forewing. D, left hind wing (C, D converted to standard right dorsal view). Scale bar = 1 mm (all to scale).

FIGURE 3. Proneuronema minor gen. et sp. nov., holotype GZG. BST. 05246, apex of female abdomen. A, photograph. B, line drawing. gx 9, gonocoxite 9; S 7, 7 th sternite; st, gonostylus of gonocoxite 9; T 7, T 8, T 9, 7 th to 9 th tergites. Scale bar = 0.5 mm.

FIGURE 4. Proneuronema minor gen. et sp. nov., specimen SMF Be 2535 as preserved. A, right side. B, left side. Scale bar = 3 mm (both to scale).

FIGURE 5. Proneuronema minor gen. et sp. nov., wing venation of the specimen SMF Be 2535. A, right forewing. B, right hind wing. C, left forewing. D, left hind wing (C, D converted to standard right dorsal view). Scale bar = 1 mm (all to scale).

FIGURE 6. Proneuronema minor gen. et sp. nov., apex of abdomen of the male specimen SMF Be 2535 (lateral view). A, photograph. B, line drawing. cc, callus cerci; ect, ectoproct; S 7, S 8, S 9, 7 th to 9 th sternites; T 8, T 9, 8 th and 9 th tergites. Scale bar = 0.3 mm.