The lacewing family Nevrorthidae (Insecta, Neuroptera) is reported from mid-Cretaceous Burmese amber for the first time. This paper describes the new genus and species Cretarophalis patrickmuelleri. Moreover, fossil nevrorthid larvae are recorded in Burmese amber for the first time. These mid-Cretaceous lacewings are the hitherto oldest representatives of the family Nevrorthidae.
The small family Nevrorthidae belongs to the insect order Neuroptera. All over the world this family comprises 19 extant species belonging to four genera. They are distributed in warm-temperate or subtropical regions, namely in the Mediterranean region, with the genus Nevrorthus (Monserrat & Gavira 2014), in South Asia with the genera Nipponeurorthus and Sinoneurorthus (Liu et al. 2012, 2014), and in southeast Australia with Austroneurorthus (Aspöck 2004). In addition, nine fossil species belonging to five extinct genera of Nevrorthidae are reported from the Eocene Baltic amber. Rophalis relicta is a very common fossil species in the Eocene; it is also found in the Bitterfeld amber (Germany) and in the Rovno amber (Ukraine). Previously, these Eocene amber species were the only known fossil nevrorthids (Wichard 2016).
In Burmese amber, an adult and two larvae of Nevrorthidae have been recently found. These amber inclusions reveal the first evidence of the presence of the family Nevrorthidae in the mid-Cretaceous (Albian—Cenomanian), with an age of about 100 million years (Shi et al. 2012; Ross 2015). In the first record of the Burmese amber arthropod taxa (Ross et al. 2010) listed six Neuroptera families: Berothidae, Coniopterygidae, Nymphidae, Osmylidae, Psychopsidae, and Rachiberothidae). Since that time some further families have been reported from Burmese amber, e.g. Babinskaiidae (Lu et al. 2017) and Dipteromantispidae (Liu et al. 2016). The small family Nevrorthidae, however, was not yet described except by Grimaldi et al. (2002: fig. 28e), who illustrated a larva of “apparent Nevrorthidae”, but this determination is doubtful (cf. Makarkin & Perkovsky 2009). Makarkin (2016) pointed to an undescribed lacewing in Xia et al. (2015, right upper photograph on page 101), which possibly proves to be an adult of the family Nevrothidae. Here, an adult specimen and larvae from Burmese amber are described.
2. Material and methods
The fossil specimens, completely embedded in small amber blocks, were cut out from larger Burmese amber pieces. An adult female is visible in ventral and dorsal view. The hindwings are partially covered by the forewings. The genitalia show signs of strong decomposition and maceration. Moreover, two larvae including mouthparts and legs are nearly completely preserved and visible in lateral view, legs partially with indication of decomposition.
The specimens were examined under a Leica M5 or MZ12.5 dissecting microscope (Leica, Wetzlar, Germany). Pictures were taken by a Leica stereomicroscope M 420 Apozoom equipped with the Canon EOS 600D using the EOS utility software and the Zerene Stacker programme. All illustrations were edited with Adobe Elements 15, using Wacom Intuos4 tablet.
Terminology: The wing venation terminology (Fig. 1) follows Kukalova-Peck & Lawrence (2004) using the venation abbreviations in text and figures: A — Analis; CuA — Cubitus Anterior; CuP — Cubitus Posterior; MA — Media Anterior; MP — Media Posterior; R — Radius; RA — Radius Anterior; RP — Radius Posterior and RP1, RP2, RP3, RP 4 or RP3+4 — subordinate branches of Radius Posterior; Sc — Subcosta. Following Oswald (1993) the forewing crossveins are arranged in more or less aligned gradate series. These series are numerically designated 1 to 4 starting at the base of the wing: 1 — basal, 2 — inner, 3 — middle, 4 — outer crossvein gradate series.
3. Systematic palaeontology
Order Neuroptera Linnaeus, 1758
Family Nevrorthidae Nakahara, 1958
Genus Cretarophalis nov.
Type species: Cretarophalis patrickmuelleri n. sp., monotypic.
Etymology: The name Cretarophalis of new genera refers to “creta” and “rophalis”. “Creta” means the Cretaceous age and “rophalis” should remember the Eocene nevrorthid genus Rophalis.
Diagnosis: See diagnosis of type species.
Cretarophalis patrickmuelleri n. sp.
Fig. 1a, b
Etymology: The species patrickmuelleri is named after Patrick Müller. His excellent collection of Burmese amber has facilitated the description of the first Cretaceous nevrorthid species.
Holotype: Female embedded in Burmese amber, kept in the collection of the Staatliches Museum für Naturkunde Stuttgart, SMNS BU-296 (ex coll. Patrick Müller). Preserved in cloudy amber, forewings visible, hindwings partially covered by forewings. Head, antennae and legs present. Female genitalia strongly decomposed.
Diagnosis: Head bearing filiform antennae with slightly enlarged scapus, smaller pedicellus and 31 uniform cylindrical flagellomeres, instead of 25 flagellomeres (Rophalis) or of 35 or more flagellomeres in case of all other extinct genera. In forewings costal crossveins simple (like in Rophalis, Electroneurothus, Palaeoneurothus) and not partially branched (like in Proberotha, Balticoneurorthus); Sc and RA running parallel to apical wing margin, only interconnected apically by a crossvein, typically of all nevrothid adults. RP pectinate, threebranched in the subordinate branches RP1, RP2, RP3; in forewing crossvein 3rp3+4 — rp2 absent (as in Rophalis). CuA with few small terminal branches.
Description: Small adult female, forewing length 4.5 mm, as small as Rophalis relicta from Eocene Baltic amber. Wings light brown, translucent, apical margin rounded. In foreand hindwings rows of setae along with the wing veins; crossveins often slightly pigmented.
Head: Ocelli absent; antennae filiform, about half as long as forewings, consisting of enlarged scapus, smaller pedicellus, following 31 flagellomeres. Maxillary palps five-segmented, labial palps three-segmented, their terminal segments pointed.
Wings: In fore- and hindwings costal crossveins all simple, not partially branched. Sc and RA running parallel to each other distantly and connected distally by a short crossvein. The area between RA and RP interrupted by three crossveins: 2ra— rp, 3ra—rp and 4ra—rp. Crossvein 2ra-rp participating in the inner crossvein gradate series, crossvein 3ra—rp in the middle crossvein gradate series and crossvein 4ra—rp in the outer crossvein gradate series. RP pectinate, three-branched in the subordinate branches RP1, RP2, RP3. In forewing crossvein 3rp3+4 — rp2 absent. MA simple, apically with terminal forks. MP with a dichotomous branch in MP1+2 and MP3+4. The longitudinal veins always divided apically into small terminal branches at margin. CuA running straight to margin, apically in both forewings pectinately branched; in right wing bifurcated, in left wing trifurcated, always with small terminal branches. CuP with a bifurcate terminal fork. Anal veins A1, A2 and A3 running separately to anal margin; in right forewing A1 with four small terminal forks, A2 with three small terminal forks.
Genitalia: Female genitalia strongly macerated and decomposed, above all densely covered by cloudy amber; outlines of the tergites of 8th and 9th segments, the ectoproct and the gonocoxite of 9th segment are passably visible.
Larvae of Nevrorthidae
Fig. 2a, b
Material: Larva in Cretaceous Burmese amber, embedded together with a cockroach (amber stored in coll. Patrick Müller); larva in Cretaceous Burmese amber (amber stored in coll. Carsten Lammerskötter).
Description: Body elongate and slender, length 7–8 mm. Head including the mandibles about 1.2 mm in length. Prothorax length about 1.2 mm, proximal part 1/3 and distal part about 2/3 of the prothorax length. Head and prothorax dorsoventrally flattened, sclerotised and brown colored. Meso-, metathorax and abdomen more cylindrical, white coloured, “verlumt”. All six legs present, with signs of decomposition and maceration. Head capsule ventrally with a long median gula, dorsally with frontoclypeus and a frontomedian triangular rostrum (ro), frontolaterally with a pair of typical filiform antennae (ant). Mouthparts with a pair of five-segmented palpus labialis (pl). Mandible and maxillary stylet forming a functional complex (md + mxst). The head is articulated at the thorax via the socalled “Rollengelenk” (Zwick 1967).
The new extinct species, Cretarophalis patrickmuelleri n. gen. et n. sp., is recorded from mid- Cretaceous Burmese amber in Southeast Asia. In the warm temperate region of Southeast Asia some extant nevrorthid species are distributed and belong to the genera Nipponeurorthus and Sinoneurorthus (Liu et al. 2012, 2014). The extinct Cretaceous species is apparently not closely related to the extant Asian taxa. The forewing venations show clear differences by comparison: 1. Costal crossveins are unbranched in Cretarophalis but patially branched in both extant genera. 2. Crossvein 3rp3+4 — rp2 is absent in the fossil species but present in Nipponeurorthus and Sinoneurorthus and present in all other extant and extinct species, except for Rophalis relicta. 3. Cubitus anterior is five- to eight-branched in Nipponeurorthus and Sinoneurorthus but two- to three-branched in the Cretaceous species Cretarophalis patrickmuelleri n. gen. et sp.
My thanks go to the reviewers, Ulrike Aspöck and Vladimir Makarkin, for providing valuable comments. I thank Patrick Müller and Carsten Lammerskötter for loaning the Burmese amber pieces with the nevrorthid inclusions. The flattened small amber with the embedded adult (holotype) is donated to the Staatliches Museum für Naturkunde, Stuttgart, Germany (SMNS) by Patrick Müller. Last but not least, many thanks to the editor Günter Schweigert for giving the paper its final shape.