Sinopolycentropus rasnitsyni Shih, Yang, Labandeira & Ren

Shih, ChungKun, Yang, Xiaoguang, Labandeira, Conrad C. & Ren, Dong, 2011, A new long-proboscid genus of Pseudopolycentropodidae (Mecoptera) from the Middle Jurassic of China and its plant-host specializations, ZooKeys 130, pp. 281-297 : 284-285

Sinopolycentropus rasnitsyni Shih, Yang, Labandeira & Ren sp. n. Figs 1,2

Material.

Holotype, an almost complete specimen with well-preserved body and wings, female, part and counterpart, No.CNU-MEC-NN-2010044 p/c, is housed in the fossil insect collection of the Key Lab of Insect Evolution and Environmental Changes, College of Life Sciences, Capital Normal University, Beijing, China.

Etymology.

The specific name is dedicated to Dr. Alexandr Rasnitsyn for his contribution to paleoentomology and his recognition, with M. V. Kozlov, of the first fossil scorpionfly ( Aneuretopsyche rostrata ) with a documented long proboscis in 1990 ( Rasnitsyn and Kozlov 1990).

Diagnosis.

As for the genus by monotypy.

Description.

A complete, small, female insect (Figs 1A-C); body length (excluding antennae and proboscis) 5.5 mm. Both forewings well-preserved, but hindwings only partially preserved, obscured due to overlap with forewings, thorax and abdomen.

Head and mouthparts. Head capsule spheroidal–prolate, prolonged anteriorly, housing prominent, hemispheroidal, and bulbous compound eyes (Figs 2A, E). Occipital region invested with conspicuously projecting, long bristles and smaller setae. Antennae 2.0 mm long, moniliform, compact and thick, with annulate hairs (Fig. 2C); about same length as proboscis. Each antenna consists of a basal scape and ca. 40 articles; each article bears hairs especially noticeable in profile along its distal annulus; proximal articles about twice as wide as long, distal articles equant. Undefined clypeal region evident below antennal base insertions and above the labrum (Fig. 2B). Mouthparts consistent with previously documented combination for pseudopolycentropodids (but see comments in discussion section below). There is the typical absence of mandibles and maxillary region, and presence of labral and labial elements; in part represented by discernable palps consisting of three articles (Figs 2B, E). Labrum triangular and inconspicuous. A long, decurved, siphonate proboscis 2.0 mm long, labially derived, occurring in an anatomically downturned position that lacks external cuticular ornamentation but bears very fine setae. Proboscis siphon diameter ca. 0.10 mm; housing an inner, eccentrically positioned food canal ca. 0.027 mm in diameter. Proboscis terminus lacks absorptive structures, such as pseudolabellae, related to feeding (Fig. 2D). Two, short labial palps present, adjacent and lateral to the proboscis base, each 0.5 mm long; about one-fourth proboscis length (Fig. 2B). Labial palps composed of three articles, the distal article slightly clavate, with a smooth, rounded terminus, the proximal articles thinner, the proximal-most attached to an enlarged labial area at the ventral base of the head capsule.

Thorax and legs. In lateral aspect pronotum short and neck-like; mesonotum broad, scutellum narrow, metanotum slightly shorter than scutum. Legs entirely covered with pubescence. Right foreleg originating from small, round coxa; long and slender femur (overlapping with thorax) and tibia (overlapping with head); left foreleg (overlapping with mouthparts) intersecting basitarsus of right foreleg and touching left antenna; tibia with at least two apical spurs. Midleg originating from small, round coxa; long and slender femur and tibia; tibia with at least 1 apical spur, tarsi of midleg 5-segmented, basitarsus longest, pretarsus with 1 evident claw. Hindleg originating from round coxa; long and slender femur and tibia; tibia with at least two, long, apical spurs. Tarsi of hindleg 5-segmented, basitarsus longest; length ratio of tibia and basitarsus 1:0.54 for left hind leg. Right hindleg disarticulated between femur and tibia.

Wings. Forewing broad, 6.1 mm long by 2.4 mm wide; length/width ratio 2.5; apical margin rounded (Figs 1A-D). (By comparison, the forewing length/width ratio is 2.0-2.3 for Pseudopolycentropus janeannae and 2.05 for Pseudopolycentropus novokshonovi. ) Membrane covered in macrotrichia. Sc short, without anterior branches; base of Sc merging with R apex; Sc reaching C considerably before than Rs origin. Humeral vein absent. Crossvein c–r perpendicular to both R1 and C, just before wing midsection. R1 rectilinear at base, slightly arched toward C near wing midsection, coursing into the distinct pt erostigma. Rs stem rectilinear. R2+R3 stem abruptly bent at crossvein r–m, then slightly arched toward C, with 2 long branches, R2 and R3. R2+R3 stem forking earlier than R4+R5; R4 longer than R2; R5 longer than R3. M forking slightly before that of Rs. Thyridium untraceable. M with 5 branches; M4+5 forking somewhat before the anterior M1+3 branch; M2+3 forking at about the same level as R4+R5 forking; M2+3 stem short and distinct. A crossvein between M4+5 stem and CuA, m–cua, near basal dc cell but present after M forking. M+CuA stem distinctly arched. M+CuA forking before R forking into R1 and Rs. Posterior wing margin almost rectilinear. Hindwing much smaller than forewing, but of similar shape. Right hindwing with only part of R2+R3 forking to R2 and R3; distal part of R4 and R5 preserved and left hindwing with a very short, terminal R1; basal Rs and part of R2+R3 forking to a preserved R2 and R3. Distal halves of fore- and hindwings suffused, pterostigma darkened (Figs 1A, 1B, 1D).

Abdomen. Abdomen elongate, tapering apically, with 9 visible segments. Basitergum (T1) fused to metathorax, segments 2-5 distinctly broad. Subgenitalis rectangular in shape and cerci visible (Figs 1B, 1C, 1E).

Locality and stratigraphic horizon.

Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China; Jiulongshan Formation, Middle Jurassic ( Bathonian–Callovian boundary interval).