Nothoderus australiensis (Alexander, 1922)

Ovtshinnikova, Olga G., Galinskaya, Tatiana V. & Lukashevich, Elena D., 2018, Skeleton and musculature of the male abdomen in Tanyderidae (Diptera, Nematocera) of the Southern Hemisphere, ZooKeys 809, pp. 55-77 : 59-64

Nothoderus australiensis (Alexander, 1922) Figures 1 C–H, 5, 6

Material.

Tasmania, Nothofagus -dominated forest, on riparian vegetation. Lake Saint Clair National Park (42°6'S, 146°9'E), 7.xii.2015, D.E. Shcherbakov, 2 males; Mystery Creek Cave (43°28'S, 146°51'E), 13.xii.2015, D.E. Shcherbakov, E.D. Lukashevich, 4 males. The specimens will be deposited in the Zoological Institute RAS, St-Petersburg, Russia.

Exoskeleton.

Abdomen: tergite I about 0.6 times as long as tergite II, sternite I about 0.3 times as long as sternite II (Figure 5). Segments II–VII well developed. Terminalia with 160-180° rotation of through segments VII–IX, with segment VIII rotated about 80-90°. Segment VIII reduced to one small sclerite situated dorsally (Figure 5B). Gonocoxites and gonostyli pubescent with long setae. Gonocoxites narrowly contiguous at base, divergent from each other at origin, each nearly cylindrical, tapered slightly toward apex (Figures 1C, 5, 6A). Gonostylus cylindrical, about 4/5 length of gonocoxite, slightly tapered at apex, curved medially, with dense macrosetae apically (Figures 1C, D, 5). Apparent hypandrium as narrow sclerotized stripe between gonocoxite bases (Figure 1E), according to muscle attachment sites (see musculature description). Epandrium slightly wider than long, with elongate setae along lateral margins and robust closely set macrosetae on two large convex lobes; tiny bare medial lobe between lateral ones; cercus inconspicuous, unmodified, setose, with semicircular rim (Figures 1D, F, 6B). Hypoproct small, situated ventrad of epandrium (Figure 6E). Paramere subdivided into dorsal bridge (pm db), dorsomedial element (pm dme) and parameral lobe at gonocoxite base (pm gbl) (Figures 1D, F, H, 6B): dorsal bridge arch-shaped, with one pair of long projections anterolaterally; dorsomedial element “I-shaped”, articulated with dorsal bridge basally and with lateral ejaculatory processes of aedeagus apically; parameral lobe at gonocoxite base bare inside and with group of elongated setae among shorter ones outside (Figure 1D, F, H). Ejaculatory apodeme extending anteriorly to segment VII, laterally compressed, clavate at base (Figure 6A, C); sperm sac balloon-like, surrounded by aedeagus posteriorly, attached to ejaculatory apodeme anteriorly; aedeagus relatively short, curved, with single trilobate phallotrema, placed between cerci when at rest (Figure 1 F–H).

Musculature.

Abdominal muscles. Tergosternal muscles TSM1 of segment I not found. Segments II–VII with one pair of wide short tergosternal muscles (TSM2-TSM7) (Figure 5B). Two pairs of long symmetrical intersegmental tergal muscles (ITM1a,b) extending from posterior part of tergite I to posterior part of tergite II; paired medial ITM1a and paired lateral ITM1b with same thickness (Figure 5B). One pair of long intersegmental sternal muscles ISM1 connecting posterior part of sternite I to posterior part of sternite II (Figure 5A). Intersegmental tergal and sternal muscles ITM2 and ISM2 connecting segment II and III not found. Intersegmental symmetrical tergal and sternal muscles ITM3a, b–ITM 5a,b and ISM3-ISM5 on segments III–VI with similar attachment sites as intersegmental muscles of segment I–II (Figure 5). Segments II–VII with wide short tergosternal muscles (TSM2-TSM7) (Figure 5B). Two pairs of intersegmental tergal muscles ITM6a,b extending from posterior part of tergite VI to anterior part of tergite VII. One pair of symmetrical wide intersegmental sternal muscles ISM6 passing from posterior part of sternite VI to anterior part of sternite VII. Posterior sites of attachment of muscles ITM6a,b and ISM6 slightly displaced clockwise (Figure 5). One pair of long asymmetrical muscles ISM7 right extending from right anterior part of sternite VII to membrane between sternite VII and epandrium. ISM7 left extending from left medial part of sternite VII to sternite VIII (Figure 5). Unpaired muscle ITM7 connecting left medial part of tergite VII to membrane between tergite VII and sternite VIII (Figure 5B).

Pregenital muscles. Short unpaired muscle M18 connecting sternite VIII to narrow sclerotized stripe or hypandrium between gonocoxite bases (Figure 5B). Narrow sclerotized stripe between gonocoxite bases interpreted as hypandrium, according to attachment sites of muscles M18. Muscles M19 not found. Segment VIII decreased to one small dorsal sclerite; tergite VIII completely membranous, sternite VIII reduced to narrow sclerite.

Tergosternal muscles. Paired, wide symmetrical M5 connecting anterolateral parts of epandrium to lateral thickenings of dorsal bridge of paramere in the point of connection of pm db with gonocoxites (= gonocoxal apodeme) (Figure 6B, C). Lateral thickenings of dorsal bridge of paramere interpreted as gonocoxites according to attachment sites of muscles M5.

Muscles of the hypandrial complex. Paired long retractors M1+2 extending from anterior edges of gonocoxites to aedeagal condyle, and also several muscle filaments of M1+2 extending from anterior edges of gonocoxites to posterior margin of dorsomedial element of paramere pm dme (Figure 6C). Paired long M23 extending from posterior edge of ejaculatory apodeme (dorsally) to membrane near aedeagus (Figure 6A). Paired wide protractors M30 extending from anterior half of ejaculatory apodeme (laterally) to anterior margin of gonocoxites (= gonocoxal apodeme) (Figure 6A, C). Paired wide retractors M31 extending from posterolateral part of ejaculatory apodeme to medial anterolateral projections of dorsal bridge pm db (Figure 6C). Paired long wide muscles M27 extending from anterior part of gonocoxites to ligament near anterior margin of gonostyli (Figure 6C). Paired long wide M28 extending from anteromedial part of gonocoxites to condyle of gonostyli (Figure 6C).

Muscles of the epandrial complex. Two pairs of M3 muscles; M31 extending from lateral parts of epandrium to anterolateral parts of hypoproct (X sternite); M32 extending from posterolateral parts of epandrium to membrane between epandrium and cercus (Figure 6D, E). Paired thin M7 extending from membrane near hypoproct to anterior lobe of cercus (Figure 6E). Hypoproct apparently partly membranous, according to site of attachment of muscles M32 and M7.