Prophora dimorion, Grimaldi, 2018

Grimaldi, David A., 2018, Basal Cyclorrhapha In Amber From The Cretaceous And Tertiary (Insecta: Diptera), And Their Relationships: Brachycera In Cretaceous Amber Part Ix David A. Grimaldi, Bulletin of the American Museum of Natural History 2018 (423), pp. 1-97 : 1-97

Prophora dimorion , new species

Figures 17 , 47C , 48

DIAGNOSIS: As for genus, by monotypy.

DESCRIPTION: Based on both sexes. Body length 1.8 mm; setae not feathered. Head: Eyes large, well separated even in male, occupying entire lateral portions of head; bare, no differentiation of facets; margins entire. Frons: Parallel sided, with well-developed median sulcus. Frontal setae: 1 large pair of fronto-orbital setae in both sexes, midway between interfrontals and verticals; 1 large pair of reclinate interfrontals in male, 3 pairs in female (anterior two pairs smaller); 1 large pair of vertical setae in male (2 pairs in female); 1 large pair of upright ocellar setae (sockets in middle of triangle) in both sexes; postocellars ca. 0.65× length of ocellars, slightly divergent. No vibrissa. Occiput near posterior margin of eye with row of fine setae, decreasing in size ventrad. Antenna: Scape very thin, ringlike; pedicel small, conical, inserted into basal flagellomere on mesal surface of flagellomere; basal flagellomere small, short ovoid; arista dorsally situated, 3-articled, basal 2 articles very short; terminal article of arista long (greater than width of head), micropubescent. Mouthparts not fully observable. Thorax: Short, stout, dorsum gently to moderately arched. Proscutellum present, well developed, lenticular, prosternum large, exposed, bare. Setae: 1 central row of ca. 10 long, fine acrostichals; row of similar setae on each side of acrostichals, anterior to dorsocentrals, shorter row lateral to these; all setae in rows decreasing in length anteriad. One large pair of dorsocentrals present; 1 large supraalar; 1 large postalar; 1 large postpronotal; row of 4 large, presutural notopleurals; 2 pairs of large scutellars (apical pair slightly longer). Pleuron without setae. Wing: Very similar in shape and vein proportions to Hennigophora robusta ; membrane with microtrichia at posterior margin only. C with short spinules, widely spaced (distance between each greater than length of spinule). Tegula with row 4 strong setae on posterior margin, basicosta with 4 setae; details of wing base with poor visibility due to preservation (e.g., development of M stem, basal cells). R 4+5 relatively short; anal lobe relatively well developed (as in Hennigophora ); alular setae long, not feathered. Legs: All pretarsi with empodium either absent or so reduced as to be unobservable at 200×; tarsomeres 1–4 with setulae in longitudinal rows, hair seam on mesal surface. Foreleg: coxa with minute, fine setulae overall; row of 6 large setae on ventrodistal margin; coxa widely separated, by distance approximately equal to thickness of coxa. Femur: Stridulatum present (as seen in male holotype: 11 scalelike teeth of scraper observed on left profemur; file not observable; no large setae on profemur. Protibia without large setae. Mid- and hindlegs: coxa with several large setae on posterior margin; femur without large setae; tibia with 1 large ventroapical seta, several smaller ones partially encircling tibial apex. Abdomen: Tergites well developed in both sexes; at least 3–4 large anterior sternites present in male (more posterior ones obscured), female with all but two terminal sternites (7 and 8) lost. Male Terminalia: Epandrium exposed, well developed, with ventral lobe (has broad attachment); surstylus articulating with lobes (not fused), clavate, pendulous. Ventral epandrial lobes, surstyli, periphallic appendages asymmetrical. Female Terminalia: Largely obscured; abdominal segments 7 and 8 much smaller than anterior ones, terminalia do not appear telescoped; hypoproct well developed.

SPECIMENS EXAMINED: Holotype, male, AMNH Bu8783; paratype, female, JZC Bu242, both in Burmese amber, well preserved, complete.

ETYMOLOGY: From Greek, di- (“two”) and morion (“parts” in genitive plural) in reference to sexual dimorphism of the head setation.

COMMENTS: Differences between the holotype male and paratype female are attributed to sexual dimorphism, otherwise the two specimens are very similar: body size and proportions, identical setation of the thorax, proportions of the wing veins, even the widely spaced costal spinules. Differences are the frontal setation, with the female having 2 additional pairs of small interfrontals (vs. 1 pair in the male), and a pair of inner verticals. Also, the female has only two small sternites (7 and 8); the male has well developed ones. Head setation is sexually dimorphic in living sciadocerines; likewise for the development of abdominal sternites in some basal Euphorida.

Figures

FIG. 17. Prophora dimorion, n. gen., n. sp. (Phoridae), paratype female in Burmese amber, JZC Bu242. A, B. Habitus, dorsal and lateral. C. Head and thorax, dorsal.

FIG. 47. Wings of Sciadocerinae preserved in Eocene Baltic amber (B, D), and Cretaceous ambers (A, C), to different scales.A. Hennigophora pria in New Jersey amber, AMNH NJ-Ch1. B. Hennigophora robusta in Baltic amber, AMNH Ba-JH51. C. Prophora dimorion in Burmese amber, JZC Bu242. D. Eosciadocera pauciseta in Baltic amber, AMNH Ba-JVe565.

FIG. 48. Prophora dimorion, n. gen., n. sp., in Burmese amber. A, C–E. Holotype male, AMNH Bu8783; B. paratype female, JZC 242. A. Head and thorax, oblique frontal view (male). B. Head, frontal view (female). C. Head and thorax, oblique posterior view. D. Body, lateral view. E. Male terminalia, right lateral view.