Proacoenonia olgae, Nel & Prokop, 2006

Nel, André & Prokop, Jakub, 2006, New fossil gall midges from the earliest Eocene French amber (Insecta, Diptera, Cecidomyiidae), Geodiversitas 28 (1), pp. 37-54 : 47-49

Proacoenonia olgae n. sp. ( Fig. 4 )

TYPE MATERIAL. — Holotype specimen PA 1599 1/2, paratype PA 1599 2/2 (in the same piece of amber).

ETYMOLOGY. — After Olga Prokopová, wife of one of us (J.P.).

DIAGNOSIS. — That of the genus.

DESCRIPTION

Head 0.15 mm long, 0.20 mm high; eyes holoptic, with mediodorsal part not separated from the two lateral parts; three ocelli; antenna 0.58 mm long, scape 0.06 mm long, 0.04 mm wide, pedicel 0.04 mm long, 0.04 mm wide, 14 flagellomeres, of nearly the same sizes, all longer than wide (0.06 mm long, 0.04 mm wide), and with a distinct neck, but nodes of flagellomeres distinctly longer than necks (ratio length of node/length of neck = 0.75), last flagellomere 0.05 mm long, flagellomeres with three rows of long curved setae, sligthly longer than the width of the flagellomere; palpus with four visible long segments, with palpal segment 1 short and stout, palpal segment 2 0.05 mm long, palpal segment 3 0.05 mm long, palpal segment 4 0.10 mm long.

Thorax 0.32 mm long, 0.20 mm high, longer than broad.

Wing 0.92 mm long, 0.46 mm wide, hyaline, macropterous, wing membrane with macrotrichia, especially in the area between R5 and M1+2; veins of posterior part of wing less strong than those of anterior part; strong anterior portion of Costa ending at apex of R5; humeral vein absent; subcostal vein very close to R, incomplete, 0.26 mm long, not reaching wing margin; vein R1 0.36 mm long, 18 times longer than Rs, reaching anterior wing margin 0.22 mm basal of apex of R5; R5 abbreviated, much shorter than wing; Rs emerging from R 10.4 mm from wing base; Rs basal of cross-vein r-m very short (0.02 mm long); cross-vein r-m distinctly longer than Rs, 0.04 mm long; vein M1+2 not forked into M1 and M2, and distinctly weaker than radius; vein M3+4 absent; CuA forked 0.43 mm from wing base, fork not very opened; CuP absent; A1 and A2 absent; anal area weakly convex; no visible pore (“Sinnesporen” sensu Jaschhof 1998) on R1, Rs, R5, and CuA (preservation?).

Haltere with large knob, 0.05 mm wide and 0.04 mm long, and stem 0.09 mm long, bare.

Legs slender, without visible scales but with numerous short setae; all tibiae with 3-4 distoventral rigid and sharp setae, stronger than other setae on the tibia but narrower than those of the recent Acoenomia ( Jaschhof 1998: fig. 42h); fore femur 0.31 mm long, tibia 0.35 mm long, tarsi 0.32 mm long; mid femur 0.34 mm long, tibia 0.18 mm long, tarsi 0.22 mm long; hind femur 0.35 mm long, tibia 0.33 mm long, tarsi 0.37 mm long; femora and tibiae not especially swollen; tibial spurs absent; empodia well developed and very setose; all legs with five tarsomes, with tarsomere 1 distinctly shorter than tarsomeres 2-4.

Abdomen (male) 0.52 mm long, 0.20 mm wide, bearing numerous long setae; genital appendages poorly visible.

DISCUSSION

Following the keys to genera of Gagné (1981) and that of Skuhravá (1997), Proacoenonia n. gen. would fall in the Acoenoniini because of the following characters: three ocelli, macropterous, M1+2 simple, CuA forked, M3 absent, R5 abbreviated, much shorter than wing, tibiae with distoventral spines. After the phylogenetic analysis of Jaschhof (1998), Proacoenonia n. gen. has two of the three autapomorphies of Acoenonia Pritchard, 1947 , unique recent genus of this tribe, viz. tibia with distal rigid and sharp setae (although narrower than those in Acoenonia ), and shortening of R5 and of distal part of C. The third apomorphy, “Sinnesporen” few, cannot be observed in Proacoenonia n. gen.

Proacoenonia n. gen. differs from Acoenonia in numerous characters: wing membrane with macrotrichia, especially in the area between R5 and M1+2; male antenna with 14 flagellomeres, instead of 12; eyes holoptic, with mediodorsal part not separated from the two lateral parts, instead of the presence of “three” eyes in Acoenonia ; tarsomere 1 distinctly shorter than tarsomeres 2-4, instead of being of the same length (at least in A. nana Meyer & Spungis, 1994 ) ( Pritchard 1947, 1960; Meyer & Spungis 1994). One further difference is the presence of four palpal segments in Proacoenonia n. gen., instead of 2-3 in the Acoenonia species.

Subfamily PORRICONDYLINAE Kieffer, 1913

Figures

FIG. 4. — Proacoenonia olgae n. gen., n. sp., holotype (PA 1599 1/2), general habitus: A, drawing; B, holotype and paratype (PA 1599 2/2), photograph. Scale bars: A, 0.5 mm; B, 1 mm.