Retiptera brennae, Cumming & Engel & Lian & Ulitzka, 2024

Cumming, Royce T., Engel, Michael S., Lian, Zhendong & Ulitzka, Manfred R., 2024, Small, intricate, and beautiful; a new species of lophioneurid from the Cretaceous (Insecta: Thripida: † Lophioneurida), Faunitaxys 12 (58), pp. 1-10 : 6-8

Horizon and age. –Upper Cretaceous ~98.79 ± 0.62 million years old ( Shi et al., 2012).

B

Preservation. – Holotype: Specimen preserved in a roughly ovular piece of amber (~14.7 x 25.2 mm; Fig. 5B). Specimen with excellent preservation, within an amber piece with excellent clarity. The amber piece has minimal debris inclusions, none obscuring the holotype, but does have many small bubbles, a few of which are near the holotype. The holotype specimen is excellently preserved and nearly complete, with the only damage being a missing terminal flagellomere on the right antenna. There are several syninclusions, namely a small coleopteran near the holotype ( Fig. 5C) and several fragmented dipteran pieces in the opposite end of the amber.

Paratype: Specimen preserved in a thin slice of amber (~13.0 x 11 mm). Specimen with excellent preservation, within an amber piece with excellent clarity. The amber piece has some debris inclusions, however none obscuring the paratype.The paratype specimen is excellently preserved and nearly complete, with a small piece of left forewing broken off, which lies beside the inclusion. Syninclusions: Remnants of an insect leg, plant detritus, and several stellate plant hairs.

Differentiation. – Currently the genus is monotypic. See the generic differentiation above for differentiation from the other two species presently known in the clade; Burmacypha longicornis and Iotacypha zherikhini.

Description

Head. – Antennae with eight segments (scapus, pedicellus, and six flagellomeres), long, originating near the base of compound eyes. Scapus stout, only slightly longer than wide with several short setae. Pedicellus slightly longer than scapus and cylindrical, longer than wide, also with several sparse setae throughout the surface. There are six flagellomeres which are ca. ½ as wide as the greatest width of the pedicellus. The flagellomeres vary in length as there are three longer followed by three shorter ([in mm] I=0.17, II=0.14, III=0.18, IV=0.11, V=0.09, VI=0.08; Fig. 4B). Each flagellomere is unadorned and simple, at most with only slight pubescence; Fig. 4B). Posterior of the head marked by three stout setae which are angled posteriorly ( Fig. 6B). Compound eyes round, large, but not overly protruding; ommatidia large and therefore few. Clypeus stout and oblong, traversing the front of the head. The mouth cone (labrum) is longer than the head and symmetrical; when viewed laterally is arcing to the apex ( Fig. 4D). Maxillary palps moderately long and thick, protruding belong the apex of the mouth cone ( Fig. 4D). Maxillary palps twosegmented with the second segment ca. twice as long as the first and marked along the dorsal surface with several prominent setae ( Fig. 4D). Labial palps shorter, only just slightly projecting beyond the apex of the mouth cone, and appear to be unsegmented.

Thorax. – Pronotum short, slightly wider than base of head, somewhat collar-like and adorned with closely packed stiff, straight setae. Mesonotum broad and prominently raised above the pronotum/head when viewed laterally; heavily adorned by short, stiff setae ( Fig. 4D). Metanotum not distinct in the specimens at hand.

Wings. – Forewing large and well-developed, projecting longer than the apex of the abdomen, about 1.57 times longer than wide. General shape is pyriform due to a narrow base widening out to a significantly broad, rounded apex ( Fig. 5D). The forewing membranes are sclerotized in regular hexagon tessellation with most cells being hexagonal in shape (most are approximately symmetrical) and the sclerotized veins between the cells are thin and angular, giving the membrane a honeycomb appearance ( Fig. 3E). Forewing venation prominent and thick (veins only slightly thinner near the apex, but still prominent). Forewing costal margin appears finely serrate ( Fig. 4E), while the other margins are relatively smooth but marked sporadically with stout, spine-like setae. The interior veins of the forewing also have these thick spine-like setae and they appear to be relatively evenly spaced. Costal margin for most of its length is relatively straight to the widest point near the distal ⅓ of the wing length where it then arcs to create a wide, rounded apex ( Fig. 3C). The anal margin is also relatively straight for most of its length until the widest point of the forewing. Sc distinct, fused with R+M+Cu at the base and runs with them for ca. ⅓ of the Sc length before the Cu splits from them, Sc then runs with the R+M for ca. ⅓ of its length, running parallel with the costal margin before it splits from R +M and runs to the costal margin slightly proximal to the wing mid length. As the Sc runs parallel with the costal margin and is spaced away from the margin, this creates a cell which is somewhat trapezoidal. Approximately ⅓ of the way through the wing length the Cu splits from the Sc+R+M vein and after a very short Cu, bifurcates at a 90 degree angle into the CuA (which runs parallel with the anal margin) and the CuP which is perpendicular to the anal margin. The Sc+R+M following the Cu split runs parallel with the costal margin until the Sc splits from it, leaving only the R+M which immediately arcs away from the costal margin for ca. the central ¼ of the wing length before the RA splits and runs slightly towards the wing base where itterminatesnear the wing mid length. Following the RA split, the Rs +M angles towards the anal/apical margin and near the distal ⅓ of the wing length near the center of the wing, the Rs1 splits and runs directly to the wing margin, terminating near the wing apex. The M following the split from the Rs+M is angled towards the anal margin and slightly back towards the base of the wing and runs for ca. ¼ of the wing width before bifurcating. The M bifurcates into the MA and MP which angle evenly away from each other (at an angle of ca. 120 degrees) with the MA terminating on the wing margin near the apical/anal margin. The MP is angled strongly back towards the wing base and fuses with the CuA and they run as a MP+CuA vein perpendicularly to the anal margin, where they terminate slightly more than halfway through the wing length. The 1A runs slightly converging with the anal margin for ca. ⅖ of the wing length before terminating on the anal margin. Approximately halfway through the 1A length the perpendicularly running CuP meets the 1A and fuses with it ( Fig. 3C). Hindwing is highly reduced and narrow, membranous, lacking sclerotization, with thinner veins than in the forewing. The hindwing is significantly narrower and shorter than the forewing (ca. ⅔ its length and about 1/7 of its width) and has a length:width ratio of 7.6 times longer than wide. The only veins present are a long fused R+M common stem which runs somewhat near the anal margin for ca. half of the wing length. Near the middle of the wing, a simple M splits at a right angle from R, and terminates near the middle of the hindwing anal margin. R runs simply for ca. ¼ of the wing length and then bifurcates on the posterior ¼ of the wing into the RA and Rs which angle strongly away from each other and terminate on the costal and anal margins respectively, near but not onto the wing apex.

Abdomen. –Abdomen short in the male holotype (~ 0.30 mm long), only extending ca. ⅓ of the way along the wings. In the specimen at hand the segmentation is somewhat indistinct, except for possibly a tapered terminal segment( Fig. 4A). The femaleparatype hasa longer abdomen(~ 0.45mm long) with more distinct segmentation, and a structure interpretable as a short ovipositor ( Fig.6A).

Legs. – Legs long, and moderately thick; femora and tibiae cylindrical, both with thin but numerous setae ( Fig. 4C). Tarsi appear to be composed of a single long segment (in the pro- and meso- legs the tarsi appear ca. ⅖ as long as the tibiae they are on, but on the long metatibiae the tarsi is only ca. ⅓ the length); simple pulvilla present and small claws.

Dimensions

- Measurements of the male holotype specimen ( Fig. 4A) which is in a flat profile view within the amber.

Body length (from front of head to apex of abdomen) 1.01 mm, Head depth (top of head to tip of mouthparts) 0.17 mm,

Head length 0.09 mm,

Thorax length 0.13 mm,

Abdomen length 0.30 mm,

Forewing length 0.88 mm,

Forewing maximum width 0.56 mm,

Hindwing length 0.61 mm,

Hindwing maximum width 0.08 mm,

Total antenna length ~ 0.86 mm,

Scapus 0.04 mm,

Pedicellus 0.05 mm,

Flagellomere I 0.17 mm,

Flagellomere II 0.14 mm,