Muscina stabulans ( Fallen , 1817)

Sorokina, Vera S. & Ovtshinnikova, Olga G., 2020, The position of the Azeliinae in the Muscidae (Diptera) based on musculature of the male terminalia, ZooKeys 975, pp. 87-110 : 87

Muscina stabulans ( Fallen, 1817) Figures 5 , 6 , 7 , 8

Material examined.

2 males, Russia, Kurgan region, Lebyazh’e district, environs of Lisje village, 55°08'N, 66°47'E, gardens, 15.vii.2019, leg. V. Sorokina. 4 males, Leningrad region, Vyborg district, Gorkovskoe railway station, Skiph, 60°17'N, 29°31'E, 1-7.viii.2018, leg. V. Sorokina.

Description.

Abdominal segments. Sternite I reduced to narrow band, tergites I and II fused. Segments III and IV and tergite V not modified; sternite V enlarged, with wide median notch.

Pregenital segments (Fig. 5 ). Tergite VI reduced to long narrow sclerotized band. Sternite VI completely membranous. Sternite VII long, narrow, positioned on left side of body, dilated at articulation with syntergosternite VII + VIII; ventrally terminates on membrane between sternites V and VII (desclerotized sternite VI), laterally connected to syntergosternite VII + VIII. Syntergosternite VII + VIII relatively wide, positioned dorsally; left end wider than right end and connected to sternite VII, right end free; posterior margin extending to epandrium.

Genitalia. Hypandrium in form of concave plate, elongated, V-shaped (Fig. 6A ); lateral arms of hypandrium articulated with surstyli and epandrium (Fig. 7A ). Pregonites and postgonites of same size and both shorter than phallapodeme; pregonites tapered distally (Fig. 6B ). Phallus containing epiphallus and distiphallus; basiphallus inconspicuous, either absent or fused with distiphallus. Phallapodeme long, articulated with phallus. Epiphallus well-developed, shaped as long, distally rounded plate. Distiphallus not large, as long as epiphallus, little expanded distally. Ejaculatory apodeme very large, sclerotized, plate-like, rounded apically (Fig. 6B ). Epandrium semispherical, with large posteromedian notch (Figs 7B , 8 ). Cerci large, wide, fused distally (Fig. 7B ). Surstylus well developed, wide, expanded and rounded apically, bent inwards, with small process. Subepandrial sclerite present as two short, quite wide, not medially connected plates, merging with surstyli (Fig. 8 ).

Thoracic muscles . Paired symmetrical conical muscles extend from thorax to lateromedian parts of tergite I + II, and also straight muscles extend from thorax to basal parts of sternite II.

Abdominal muscles (Fig. 5 ): ITM 2-ITM 4, ITM 5a, ITM 5b, ISM 2-ISM 5, TSM 1-TSM 5. Flat, very short muscles ITM 2-ITM 4 extend from distal parts of tergites II-IV along their entire width to basal margins of tergites III-V. Paired and slightly asymmetrical muscles ITM 5a extend from median parts of tergite V to lateromedian parts of basal margin of tergite VI. Long, paired, slightly asymmetrical conical muscles ITM 5b extend from laterobasal parts of tergite V to membrane at lateral parts of tergite VI.

Paired symmetrical muscles ISM 2-ISM 4 extend along entire basal margin of sternites II-IV to basal margins of sternites III-V, respectively. Paired symmetrical muscles ISM 5 extend in two layers from sternite V to membrane between sternite V and sternite VII (membranous sternite VI), spread along this membrane, and extend to sternite VII at connection with membrane of sternite VI (powerful, fan-shaped muscles ). Muscles extending along membrane of sternite VI (lower layer) connected with distal part of sternite V, but muscles extending to sternite VII (upper layer) connected with basal part of sternite V. Wide and flat pleural abdominal muscles TSM 1-TSM 5 easily discernible on corresponding segments.

Pregenital muscles (Figs 5 , 6A , 7A , 8 ): ITM 6, ISM 6, ISM 7, TSM 7, M 18, M 191, M 192. Small and short, paired, slightly asymmetrical muscles ITM 6 extend from lateral parts of tergite VI to lateral parts of syntergosternite VII + VIII.

Paired muscles ISM 6: left ISM 6 extends from left part of membrane of sternite VI to lateral margin of inner surface of sternite VII close to articulation with syntergosternite VII + VIII; right muscle ISM 6 extends from right parts of membrane of sternite VI to membrane near right laterobasal margin of syntergosternite VII + VIII; left ISM 6 larger than right muscle ISM 6. Unpaired left muscle ISM 7 short, powerful, extending from lateral margin of outer surface of sternite VII to outgrowth on lateral part of basal margin of syntergosternite VII + VIII. Paired asymmetrical muscles TSM 7: left muscle TSM 7 wide, short, fan-shaped, extending from lateral part of inner surface of sternite VII to small outgrowth on lateral margin of syntergosternite VII + VIII; right muscle TSM 7 fan-shaped, extending from right basal margin of sternite VII to small sclerite adjacent to syntergosternite VII + VIII.

Paired asymmetrical muscles M 18: right muscle M 18 r wide and flat, extending from membrane covering genital cavity near syntergosternite VII + VIII to middle of basal margin of hypandrium (Figs 6A , 7A ); left muscle M 18 l long, extending from lateromedian left part of syntergosternite VII + VIII to inner surface of left laterobasal part of hypandrium. Paired asymmetrical muscles M 191 (Fig. 8 ): left muscle M 191 l powerful, extending from inner surface of left lateral part of syntergosternite VII + VIII (close to connection with sternite VII) to small area of left lateral margin of epandrium at connection with hypandrium; right muscle M 191 r weaker than M 191 l, extending from right part of syntergosternite VII + VIII to right lateral margin of epandrium at connection with hypandrium. Unpaired muscle M 192 powerful, fan-shaped, and oblique, extending from right lateral part of syntergosternite VII + VIII to slightly to right from middle of basal margin of epandrium.

Genital muscles . Tergosternal muscles (Fig. 7A ): M 5. Paired, symmetrical, powerful muscles M 5 extend from lateral parts of basal margin of hypandrium to lateral parts of basal margin of epandrium.

Muscles of hypandrial complex (Fig. 6 ): M 1, M 21, M 22, M 23, M 23. Wide and powerful, paired, symmetrical muscles M 1 extend from hypandrium, occupying considerable part of inner surface, to basal part of phallapodeme in front of pregonites. Paired symmetrical muscles M 21 extend from base of hypandrial arms to laterodistal parts of phallapodeme, opposite hypandrium. Long paired symmetrical muscles M 22 extend almost from entire basal part of pregonites to distal half of phallapodeme, opposite hypandrium. Symmetrical muscles M 23 long and close to each other, extending from membranous basal margin of epiphallus to distal part of phallapodeme, opposite epandrium.

Constrictors of ejaculatory apodeme wide and powerful; muscles M 23 surrounding ejaculatory apodeme and extending from rounded wide margin to tapered margin, contraction pumps seminal fluid into phallus.

Muscles of epandrial complex (Figs 7 , 8 ): M 3, M 4, M 7, M 24-M 26. Powerful paired symmetrical muscles M 3 extend from inner surface of basal parts of epandrium to inner surface of subepandrial sclerite. Powerful paired symmetrical muscles M 4 extend from lateral parts of inner surface of epandrium to inner surface of basal parts of surstyli. Paired symmetrical short and thin cercal muscles M 7 extend from inner part of basal part of subepandrial sclerite to laterobasal parts of cerci. Broad powerful muscle M 24 passes inside cerci, connecting lateral parts of two halves of cerci. Broad paired muscles M 25 extend from median parts of epandrium to integument of anus. Powerful, fan-shaped, paired symmetrical muscles M 26 extend from distolateral parts of epandrium (more medially than M 4) to lateral cercal outgrowths.

Figures

Figure 5. Muscina stabulans (Fallen, 1817). Male pregenital segments, inner view. Upper muscles ISM 5 removed left and lower muscles ISM 5 removed right.

Figure 6. Male genitalia of Muscina stabulans (Fallen, 1817) A hypandrium, inner view B aedeagal complex, lateral view.

Figure 7. Male genitalia of Muscina stabulans (Fallen, 1817) A genitalia, lateral view B epandrial complex, dorsal view.

Figure 8. Male genitalia of Muscina stabulans (Fallen, 1817). Epandrial complex, inner view.