Eucaudomyia longicerci, Grimaldi, 2016

Grimaldi, David A., 2016, Diverse Orthorrhaphan Flies (Insecta: Diptera: Brachycera) In Amber From The Cretaceous Of Myanmar: Brachycera In Cretaceous Amber, Part Vii David A. Grimaldi, Bulletin of the American Museum of Natural History 2016 (408), pp. 1-132 : 86-89

Eucaudomyia longicerci , new species

Figures 30 , 31 , 61–63

DIAGNOSIS: As for genus, by monotypy.

DESCRIPTION: Based on female. Holotype, paratype respectively: body length 5.33, 5.51 mm; wing length 2.38, 2.90 mm; thorax length 0.72, (not measured) mm; thorax width 1.18, (not measured) mm; head width 0.73, (not measured) mm; midleg length 1.87, (not measured) mm; abdomen length (including cerci) (not measured), 3.77 mm; length of cerci + telescoping abdominal segments 2.62, (not measured) mm. Head: Subspherical, relatively small in proportion to thorax; eye large, mouthparts vestigial. Eye bare, no interfacetal setulae; no differentiation of facets in female (male unknown); frontal and dorsal margins of eyes close but not touching, separated by distance ca. 3–4× diameter of eye facet; eyes occupying most of head (especially dorsally and ventrally); gena large and exposed. Ocelli present, well developed; ocellar triangle darkly pigmented, close to posterior margin of head capsule. Face very narrow, width 3–4× diameter of eye facets, with prominent vertical carina/ridge near the middle. Antenna: With insertions on opposite sides of carina (not on carina edge); antenna short, 0.10 mm length; slender, 0.01 mm thickness, apparently bare (with possible exception of apical setulae); 2-segmented, with short ringlike basal segment (presumably pedicel), and slender, slightly clavate-digitate postpedicel article (flagellum). Mouthparts: Highly vestigial, lacking labellum, theca, and maxillary palps; mouth opening present as a small subcircular ostiole (diameter ca. 0.05 mm). Anterodorsal to mouth opening is a tongue-shaped sclerite, possibly the clypeus. Posteroventral to the mouth opening is small, broad sclerite, 0.1 × 0.1 mm, probably the labium (though if internal as it appears, possibly the ventral floor of the cibarium); attached to this sclerite is a small, hourglass-shaped one, possibly the dorsal keel of cibarium. A small, heavily sclerotized, free sclerite internally, bearing a nipplelike lobe, which is possibly a vestigial cibarium. Thorax: Very broad, width 1.7× width of head; without macrosetae, with only fine, sparse/ scattered setulae. Insertion of cervical area ventral, not anterior. Dorsum of mesonotum slightly humped, with steep, slightly concave incline meeting scutellum; notum with pair of paramedian, shallow, incomplete furrows extending from posterior margin of notum to ca. 0.8× length of notum (not reaching anterior margin). Pronotum a broad, very thin collar. Scutellum a very small, posterior lobe. Pleuron not visible. Sternal region well preserved and visible in JZC Bu-241: katepisterna virtually form a ventral floor of the thorax (very little exposed laterally); proepimeron large, triangular, about half the size of katepisternum; sutures between katepispternum, proepimeron, anepisternum and anepimeron forming large, symmetrical X (fig. 62E). Thoracic phragmas highly reduced. Coxal articulations of both legs in each pair nearly touching; distance between ipsilateral pro- and mesocoxae approximately equal to diameter of articulation; distance between ipsilateral meso- and metacoxae twice this diameter. Legs: Without large setae or spines, only fine decumbent setulae. Coxae thick, slightly crassate; trochanters ca. 0.3× width of coxa; femur slightly longer than synpodal tibia; no apical tibial spurs; tarsus short, ca. 0.5× length of tibia; basitarsomere short (even metathoracic ones), slightly longer than other tarsomeres. Individual tarsomere lengths: 1> 2 = 5> 3> 4. Pretarsus with padlike empodium and pulvillus, pads relatively small, barely extending beyond claws; claws well developed (no preapical teeth), stout, thick at base. Wing: Simple, apically rounded; venation highly reduced. Vein C present only for one-half length of wing along C margin, without spinules; Sc thin, complete, slightly shorter than C (obscured in furrow between C and R 1). R 1 thick, sclerotized, slightly thicker where it meets C, diverging apically slightly away from wing margin. Rs simple, no branches, arched, running near middle of wing, apically evanescent. Vein M a short, basal spur <0.20× wing length. CuA arched, virtually complete, apically evanescent; CuP present near and parallel to CuA. Anal lobe essentially absent. Dense, fine microtrichia over entire membrane. Halter short, thick, with long ovoid apical knob; knob 0.6× entire length of halter, with narrow apex and longitudinal fold; small lobe on posterior margin of stem. Abdomen: Anterior portion (segments 1 to 6) short, broad in female (male unknown); greatest width (at tergite 2) approximately equal to width of thorax, tapered posteriad. Length of tergites 1 to 6 0.9× the greatest width of abdomen; width of segment 6 0.6× that of segment 2. Oviscapt very long, comprised of segments 7, 8 (possibly a 9th segment), cerci, and epiproct. Length of oviscapt 3.1× length of abdomen, 1.12× length of rest of body. Oviscapt: segment 7 funnel shaped at base, tubular apically, with notch on dorsal margin, length 0.6 mm (including section telescoped into segment 6), glabrous; segment 8 tubular and glabrous, also with dorsoapical notch, length 1.1 mm (including section telescoped into segment 7); cerci developed into pair of long, digitate, valvelike lobes (length 1.6 mm) flexed ventrally under segments 7 and 8 (elbow pivot between cerci and apex of segment 8), inner surfaces of cerci concave, dorsal surface closed by elongate epiproct (length 1.3 mm). Oviscapt apparently not any more sclerotized than rest of abdomen; cerci with fine, decumbent setulae (not glabrous); apices of cerci not particularly pointed, “valves” separated. Eggs (seen in paratype): small, ovoid, length 0.1 mm, width 0.05 mm, matured at least 15 at one time, passed through at least segment 8 (and probably through cercal “valves”).

TYPES: Holotype, female, JZC Bu-241. Paratype, female, Di-Ying Huang collection, Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China.

ETYMOLOGY: Latinized version from Greek, meaning “of the long cerci,” treated as a noun in apposition; in reference to the elongate cerci in the female.

COMMENTS: The holotype is a small, trimmed, polished piece 8 × 7 × 2 mm with a suspension of fine bubbles; fly is fully exposed dorsally and ventrally, with a frontal view of the head. The dorsum of the thorax and head are decayed away, but these tagmata are cleared, better exposing sutures, minute and internal structures such as the vestigial mouthparts. The paratype specimen is in an oblong piece 17 × 8 × 5 mm, which appears to be a segment of a runnel. Preservation of the paratype is fair to good: thoracic dorsum is visible, left side partially decayed, the head dorsoventrally compressed, ocellar triangle fully visible. Dorsum of abdomen and oviscapt are fully visible; much of the ventrum is obscured by a layer of air over the surface and by compression; mouthparts and sternites are entirely obscured. Legs and wings are mostly visible.

Figures

FIG. 30. Eucaudomyia longicerci, new genus and species (Eucaudomyiidae, new family), holotype JZC Bu-241. A. Wing. B. Female terminalia, ventral view. C. Anterior portion of head (frontal view), with antenna and vestigial mouthparts. D. Mouthparts, interior view (specimen was cleared). E. Apical tarsomeres and pretarsus. Panels C−E to same scale.

FIG. 31. Eucaudomyia longicerci, new genus and species, reconstruction of female dorsal habitus, based on holotype and paratype. The small circular structures within the base of the abdomen must be eggs (seen in paratype specimen).

FIG. 61. Eucaudomyia longicerci, new genus and species (Eucaudomyia, new family), paratype Huang coll., IGP, Nanjing. A. Habitus, dorsal. B. Habitus, ventral. C. Abdomen with telescoping abdomen and long cerci, left lateral.

FIG. 62. Eucaudomyia longicerci, holotype JZC Bu-241. A. Habitus, dorsal. The head and thorax are cleared. B. Head and thorax, dorsal. C. Head, ventral. D. Head, dorsal. E. Thorax, ventral, showing peculiar arrangement of sternites and pleurites. F. Left wing.

FIG. 63. Eucaudomyia longicerci, holotype. A. Tarsi. B. Abdomen, dorsal. C. Telescoping portion of abdomen and cerci, ventral.