Psectrosciara makrochaites Amorim and Greenwalt, 2022

Greenwalt, Dale E., Amorim, Dalton De Souza, Hauser, Martin, Kerr, Peter H., Fitzgerald, Scott J., Winterton, Shaun L., Cumming, Jeffrey M., Evenhuis, Neal L. & Sinclair, Bradley J., 2022, Diptera of the Middle Eocene Kishenehn Formation II, Palaeontologia Electronica (a 22) 25 (2), pp. 1-52 : 4

Psectrosciara makrochaites Amorim and Greenwalt sp. n.

Figure 1 D-F

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Type species. Psectrosciara mahensis Kieffer, 1911 [= Psectrosciara brunnescens ( Brunetti, 1911) ], by original description.

Holotype. Female, USNM 625934 , deposited in the Paleobiology collections of the National Museum of Natural History in Washington, D.C.

Locality and horizon. Deep Ford site, Middle Fork of the Flathead River (Pinnacle, Montana, USA). Middle Eocene Coal Creek Member, Kishenehn Formation.

Etymology. The species epithet makrochaites is derived from the Greek words makro (long) and chaite (long hair, mane) in reference to the long hair on the abdomen of this species.

Diagnosis. Psectrosciara makrochaites i s differentiated from Psectrosciara fossilis by M 1 incomplete, interrupted at its base and from Psectrosciara crassieton by its relatively slim habitus.

Description. Female. Body length, 3.0 mm. Head dark brown, 0.24 mm long, 0.29 mm high; antenna uniformly dark brown, 0.25 mm long, flagellum with seven flagellomeres, terminal flagellomere elongated, 68 μm long, 60 μm wide; palpus light brown, elongated, 70 μm long, 24 μm wide, setose; labellum light brown. Thorax dark brown, longer than wide, 0.6 mm long; scutum apparently bare—some recent species have fine scattered setae, which is probably the case in the fossils, with these setae not preserved ( Figure 1 A-B). Fore leg dark brown, mid and hind legs lighter in color, coxae light brown; length of femora, tibiae and tarsomeres 1-5: 0.33 mm, 0.30 mm, 0.12 mm, 0.05 mm, 0.05 mm, 0.05 mm and 0.06 mm long (fore leg), 0.24 mm, 0.21 mm, 0.13 and 0.07 mm long (mid leg, last three tarsomeres not visible); and 0.36 mm, 0.30 mm, 0.17 mm, 0.08 mm, 0.06 mm, 0.04 mm 0.05 mm long (hind leg). Anteroapical quarter of hind femur not pigmented; claws pointed, apparently no tooth on tarsal claw. First tarsomere of fore and hind legs not particularly modified, with differentiated spines or stout setae ( Figure 1E ). Wing, 1.5 mm long, 0.5 mm wide, macrotrichia present. Wing length (WL)/C section 1 (C1) ratio, 3.43; WL/C2, 2.43; WL/C3, 3.21; C1+C2/WL, 0.70. Sc apparently absent, basal portion of M 1 absent, basal portions of M 2 and M 4 not visible, CuA sigmoid ( Figure 1 C-D). Abdomen, 2.2 mm long, 0.4 mm high; tergites brown, with light intersegmental areas, tergites covered laterally with long, thin hairs, 0.1 mm long, perhaps twice that long; spermatheca sclerotized, 85 mm in diameter. Tergite and sternite 7 dark brown, sternite 8 thinly sclerotized, yellowish, tergite 8+9 yellowish, slightly projecting beyond tip of T7 ( Figure 1F ).

Male. Unknown.

Synimpressions. Diptera (1).

Figures

FIGURE 1. Psectrosciara makrochaites Amorim and Greenwalt sp. n., female, USNM 625934 and P. crassieton Amorim and Greenwalt sp. n., female, USNM 625035. A, P. makrochaites, habitus; B, Head and antennae; C, Wing, veins M1, M2 and CuA; black arrows denote long abdominal hairs; D, Microsetae on wing surface; E, Legs. Short arrow denotes fore tibia not produced beyond base of tarsus, long arrow denotes apex of hind tibia not club-shaped, swollen at apex; F, Genitalia, spermatheca; G, P. crassieton, habitus. Scale bars equal 1.0 mm (A, G), 0.5 mm (B), 0.3 mm (C), and 0.2 mm (D-F).