Macrorrhyncha borealis Fitzgerald, 2023

Fitzgerald, Scott J., 2023, The Nearctic species of Asindulum Latreille and Macrorrhyncha Winnertz (Diptera: Keroplatidae), Zootaxa 5351 (1), pp. 72-106 : 94-98

Macrorrhyncha borealis Fitzgerald n. sp.

Figs. 64–74

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Type material. Holotype male ( Fig. 64 ) ( CNCI), pinned, terminalia dissected: CANADA: YUKON TERRITORY: Canyon Creek , 4 Aug. 1948, Mason & Hughes. A second smaller blue label (“ SLIDE, HCW, 6.I.77, No. F ”) refers to the slide-mounted right wing.

Additional material examined (tentatively associated; see Comments below). CANADA: BRITISH COLUMBIA: Alaska Bay , Lum & Abner, 58 degrees N., 29 Aug. 1948, Mason & Hughes, 1 female ( CNCI) ; SASKATCHEWAN: Hudson Bay , 13.IX.1959, J. R . Vockeroth, 1 specimen (missing terminalia, sex unknown) ( CNCI) .

Description. Holotype male. Body length ca. 4.5 mm (n = 1). Head, antennae, mouthparts dark brown. Antennae with 14 cylindrical, barrel-shaped flagellomeres plus a minute, apical, button-like apicule, all without distinct setae. Mouthparts as Fig. 65 ; very long, terminating well beyond apex of fore coxa. Palps five-segmented. Three centrally-positioned ocelli in an arc; median ocellus smaller. Mesonotum dark brown, slightly lighter brown laterally, with short black setae in broad irregular rows medially, dorsocentrally, and laterally. Thoracic pleura dark brown; anepisternum, katepisternum, laterotergite, and mediotergite bare. Posterior edge of anterior spiracle with several short black setae. Legs light brownish-yellow; left fore leg and right fore tarsus missing. Tibial spurs 1:2:2 with inner spurs longer. Fore tibia with apical, triangular sensory area on anterior surface. Hind tibia with trichia irregularly arranged and a small number of short black setae in regular rows on anteroventral, anterior, anterodorsal, dorsal, posterodorsal, and posterior surfaces. Wing ca. 3.8 mm (n = 1), hyaline. Posteroapical portion of left wing missing, right wing slide-mounted ( Fig. 66 ). Veins brown, anterior and posterior forks and CuP with short, widely-spaced setae on upper surface, especially apically. Anterior veins with more densely-spaced setae except Sc, base Rs, and R 2+3 bare. CuP not reaching wing margin. Halters brownish-yellow. Abdomen dark brown with short black setae. Male terminalia as Figs. 67–72 . Male tergite 9 approximately square, anterior margin with deep, broad, u-shaped emargination and posterior margin with slight, broad, emargination; without strongly developed posterolateral lobes. In dorsal view, cerci prominent, triangular, fleshy, setose. Ventrally, gonocoxites with deep, broad u-shaped emargination which nearly subdivides sclerite; a narrow strip of sclerite anteriorly connecting the two halves. In ventral view, a small lobe (terminating with a cluster of setae) is visible on the inner surface of the gonocoxite immediately below the attachment-point of the gonostyli. In lateral view, gonocoxites short, broad, broadly rounded with a short, broad, apically broadly rounded, asetose dorsal process that is shorter than (i.e. does not reach the level of the posterior apex of) the primary lobe of the gonocoxite. Gonostylus triangular in ventral view. In lateral view gonostylus somewhat triangular with tip slightly curved dorsally and with a long, thin, slightly curved, asetose, dorsally-projecting lobe which originates basally. Sperm pump (possibly fused with parameres?) large and anteriorly elongated, with apodemes reaching to anterior end of abdominal segment 7; notable are two pairs of very long, ventrolaterally-positioned apodemes (one pair laterally flattened and the second pair more rod-like) and an ejaculatory apodeme which is the longest of all the apodemes and the most strongly laterally compressed. Additionally, there is a pair of short, divergent apodemes dorsally. The posterior apex of the sperm pump is made up of two pairs of rounded lobes; a larger, dorsoventrally-flattened pair more ventrally (visible in Fig. 68 ), and a smaller, laterally-flattened pair that is more centrally located.

Female (tentatively associated; see Comments below). As in male except: Body length ca. 4.5 mm (n = 1). Mesonotum light brown laterally. Wing 4.5 mm. Abdomen broader than male. Female terminalia as Figs. 73–74 . Cerci fleshy, setose, oval, pad-like. Sternite 10 difficult to discern due to being retracted, but appears to be rounded posteriorly.

Etymology. The specific epithet is from Latin “ borealis ” (northern), referring to the northern distribution of this species.

Diagnosis. Mouthparts very long (terminating well beyond apex of fore coxa), thorax dark, and male terminalia as Figs. 67–72 .

Comments. The specimens listed above as M. borealis were associated with the box label “ Macrorrhyncha coxale ” in CNCI and the slide-mounted right wing of the holotype is labelled as “ Macrorrhyncha coxalis Lw. ” The note “IDEMA” on the slide indicates that the specimen was used for the illustration of the wing of “ Macrorrhyncha coxalis ” in the Manual of Nearctic Diptera ( Vockeroth 1981, Fig. 17 ); this figure caption should be corrected to “ M. borealis .”

The two specimens listed under “additional material examined” are only tentatively included here as one is missing the terminalia and the second is a female from a different site than the holotype male. However, both specimens have the thorax dark-colored and mouthparts longer than fore coxa which are characters unique to M. borealis in the known Nearctic species. While it is possible that one or both of these specimens represents an undescribed species, they are here associated with M. borealis as a working-hypothesis until further evidence can either confirm or refute this association. Based on keys and illustrations of the Palearctic species ( Matile 1975, Bechev 2010b), this species is similar to M. hispanica (Strobl) , though the dorsal process of the gonocoxite is shorter rather than taller than the remainder of the gonocoxite and the gonostylus is distinctly different in shape.

Distribution. Canada.

Figures

FIGURE 66. Macrorrhyncha borealis n. sp., holotype male. 64. Wing. Scale = ca. 0.5 mm. Abbreviations: CuP, posterior branch of cubital vein.

FIGURES 64–65. Macrorrhyncha borealis n. sp., holotype male. 64. Habitus. Scale = ca. 1.0 mm. 65. Head, anterolateral. Scale = ca. 0.5 mm. Abbreviations: cx1, coxa 1; lbl, labellum.

FIGURES 67–70. Macrorrhyncha borealis n. sp., holotype male, terminalia. 67. Dorsal. 68. Ventral. 69. Lateral. 70. Posterior. Scale bar = ca. 0.25 mm.Abbreviations: bl, basal lobe of gonostylus; ce, cercus; dp, dorsal process of gonocoxite; gc, gonocoxite; gs, gonostylus; t9, tergite 9.

FIGURES 71–72. Macrorrhyncha borealis n. sp., holotype male, terminalia including sperm pump. 71. Ventral. 72. Lateral. Scale = ca. 0.25 mm. Abbreviations: ea, ejaculatory apodeme; gc, gonocoxite; t9, tergite 9.

FIGURES 73–74. Macrorrhyncha borealis n. sp.? (female, tentatively associated), female terminalia. 73. Dorsal. 74. Ventral. Scale = ca. 0.25 mm. Abbreviations: ce, cercus; sp, spermathecae; s8, sternite 8; t7, tergite 7.

FIGURES 16–18. Asindulum flavidum n. sp., holotype male. 16. Habitus, lateral. 17. Head, anterior. 18. Wing. Scale bars = ca. 1.0 mm. Abbreviations: CuP, posterior branch of cubital vein; cx1, coxa 1; lbl, labellum.