Astreptolabis laevis, Mao & Engel & Ren & Gao, 2020

Mao, Yue, Engel, Michael S., Ren, Dong & Gao, Taiping, 2020, A new species of Astreptolabis in mid-Cretaceous amber from northern Myanmar, with the discovery of the first male of Astreptolabidinae (Dermaptera), ZooKeys 911, pp. 101-112 : 101

Astreptolabis laevis sp. nov. Figs 1 , 2 , 3 , 4

Diagnosis.

The new species can be distinguished from A. ethirosomatia on the basis of the more sparse setation, particularly on the head, pronotum, and tegmina (distinctly and minutely hirsute in A. ethirosomatia ); the larger compound eyes, which encompass the entire lateral surface of the head from the antennal articulations to the posterior border (in A. ethirosomatia the compound eyes are smaller, distinctly separated anteriorly from the antennal base and posteriorly from the temple margin); distance between compound eyes subequal to compound eye length (distance between compound eyes in A. ethirosomatia distinctly greater than compound eye length); absence of ocular setae (present in A. ethirosomatia ). On the surface there would appear to be further proportional differences between the new species and the type species, but the holotype of A. ethirosomatia is poorly preserved and largely compressed with considerable taphonomic distortion ( Engel 2011).

Description.

Female: Total length as preserved (including cerci) ca. 3.61 mm (Fig. 1 ); sparsely setose; head medial length from clypeal apex to posterior border 0.47 mm, maximum width (across level of compound eyes) 0.59 mm; compound eye length 0.25 mm, separated from posterior border of head by minute distance. Pronotum medial length 0.51 mm, anterior width 0.37 mm, posterior width 0.60 mm (Fig. 2A ); tegmen length 1.18 mm, maximum width 0.46 mm. Abdominal length as preserved (excluding cerci) 1.43 mm, maximum width 0.54 mm; second tarsomere shortest but almost as long as third tarsomere; arolium vestigial; cercal forceps length 0.61 mm, basal width 0.07 mm, separation between bases 0.05 mm. Integument as preserved dark brown, punctate, somewhat smooth throughout. Legs without spines or bristle-like setae (Fig. 2C ). Valvulae extending slightly beyond apex of subgenital plate (Fig. 2D ).

Hind wings well developed (Fig. 1 ); area of hindwing 0.5 mm2 folded, 2.9 mm2 unfolded; squama sclerotized, extending a little beyond apex of tegmina; ulnary area distad squama; eight radiating veins and eight intercalary veins in anal area, with concave and convex folding lines between them; ring fold running through anal fan, intersecting with radiating and intercalary veins in broadened areas (Figs 1 , 2B ).

Male: Total length as preserved (including cerci) ca. 5.30 mm (Fig. 4A, B ); sparsely setose; head medial length from clypeal apex to posterior border 0.47 mm, maximum width (across level of compound eyes) 0.71 mm. Pronotum medial length 0.61 mm, anterior width 0.46 mm, posterior width 0.72 mm; tegmen length 1.53 mm, maximum width 0.64 mm. Abdominal length as preserved (excluding cerci) 1.96 mm; second tarsomere shortest but almost as long as the third; arolium vestigial (Fig. 4C ); cercal forceps length 0.74 mm. Integument as preserved brown, somewhat smooth throughout. Legs without spines or bristle-like setae. Parameres broad, tapering to acute apex, without incisions or teeth, with a series of sensory setae along inner margin; two virgae extended, apically, with comb-like accessory sclerites positioned ventrally on distal lobes (Fig. 4D, E ).

Hind wing well developed, congruent with the description above, and unfolded.

Remarks.

The hind wing of the holotype of A. laevis is well preserved, and one is unfolded and extended. The base of the hind wing is obscured because of the position of the specimen, but most of the preserved structures are similar to those of extant earwigs. The female paratype CNU-DER-MA2018002 shares the same characters with the holotype, but the integument of this paratype is somewhat roughened and the pronotum seems broader than the holotype; however, these differences may be the result of taphonomy. The male paratype CNU-DER-MA2018003 shares the same characters with the holotype except for a larger body size, which seems to be a sexual difference. Otherwise, differences in body size are mainly reflected in tegmen length and abdominal length which are longer than the female, but otherwise proportional.

Type material.

Holotype, ♀, CNU-DER-MA2018001, dorsal view, a well-preserved complete female. Paratype ♀ CNU-DER-MA2018002, dorsal view, a well-preserved complete female. Paratype ♂, CNU-DER-MA2018003. All type material deposited in College of Life Sciences, Capital Normal University, Beijing, China.

Locality and horizon.

Hukawng Valley, Kachin State, northern Myanmar; lowermost Cenomanian, mid-Cretaceous.

Etymology.

The specific epithet is the Latin word laevis, meaning, “polished” or “smooth”, in reference the integumental surface of the species.

Figures

Figure 1. Astreptolabis laevis sp. nov., holotype, CNU-DER-MA 2018001 A photo B line drawing. Scale bars: 0.5 mm.

Figure 2. Astreptolabis laevis sp. nov., holotype, CNU-DER-MA 2018001 A photo of pronotum B line drawing of hind wing C photo of legs D photo of vavula. Scale bars: 0.2 mm (A, C), 0.5 mm (B), 0.1 mm (D).

Figure 3. Astreptolabis laevis sp. nov., paratype, CNU-DER-MA 2018002 A photo B line drawing C photo of legs D photo of cerci. Scale bars: 0.5 mm (A, B), 0.2 mm (C), 0.1 mm (D).

Figure 4. Astreptolabis laevis sp. nov., paratype, CNU-DER-MA 2018003 A dorsal view B ventral view C photo of pronotum and legs D photo of male genitalia E enlarged view of male genitalia. Scale bars: 1 mm (A, B), 0.5 mm (C), 0.2 mm (D), 0.1 mm (E).