Hydrosmittia virgo (Strenzke) Ferrington Jr & Saether, 2011

Ferrington Jr, Leonard C. & Saether, Ole A., 2011, A revision of the genera Pseudosmittia Edwards, 1932, Allocladius Kieffer, 1913, and Hydrosmittia gen. n. (Diptera: Chironomidae, Orthocladiinae) 2849, Zootaxa 2849 (1), pp. 1-314 : 126-129

Hydrosmittia virgo (Strenzke) comb. n.

( Fig. 45 )

Pseudosmittia virgo virgo Strenzke, 1950: 303 . Pseudosmittia holsata, Thienemann et Strenzke 1940: 240 , female pupa and larva, not male and female pupa.

Pseudosmittia virgo Strenzke ; Schmid 1993: 180, fig. 124.

not Pseudosmittia virgo montana Strenzke, 1950: 303 (= P. montana ).

Material examined: GERMANY: Schleswig-Holstein, Holstein , holotype male, 1940/41 No. 346 (GP731); paratypes, 2 females, 5 pupal exuviae, 1 misidentified larva of A. arenarius , as holotype (GP732, 733, 735), other material, 1 pupal exuviae, as holotype (GP734) . NORWAY: Hordaland, Vaksdal, Ekso River , weir basin, 4 larvae, 7 vii 1976, R. Larson, 17.vii.1984, 6.xi.1984, G. Raddum ( ZMBN) . GREENLAND: 11 larvae, 1949, leg. Delasse, det. K. Strenzke, No. 10, no further data (GP730) ( NMS) .

Diagnostic characters: The female imago is characterized by having well developed median antepronotal lobes, 2 acrostichals, Cu 1 sinuate, R 4+5 ending distal to the apex of M 3+4, costa between FR and apex of R 4+5 with 17–23 nonmarginal setae, and seminal capsules with rather strong microtrichia. The pupa lacks frontal setae and anal macrosetae like the two preceding species, has few or no spinules on tergal conjunctives II/III and VII/VIII like H. ruttneri , but differs from the last species in having no or very faint shagreen on sternite I. The larva has a mandible with 3 inner teeth, posterior parapods with 7–10 claws and postmentum length of 70–85 µm in the fourth instar.

Female imago (n = 2–3)

Total length 1.75–1.82 mm. Wing length 1.04–1.08 mm. Total length/ wing length 1.69–1.72. Wing length/length of profemur 3.58–3.62. Coloration blackish brown.

Head. AR 0.39–0.43. Flagellomeres 3–5 slightly flask-shaped, no apical strong seta ( Fig. 45 B ). Length (in µm) of flagellomeres: 18–23, 32–39, 59–71, 53–59, 73–87. Temporal setae 4–5, including 1–2 inner verticals and 3 outer verticals. Clypeus with 9–11 setae. Tentorium 85–89 µm long, 11–13 µm wide. Stipes 69–91 µm long, 34 µm wide. Palpomere lengths (in µm): 18–23, 32–39, 59–71, 53–59, 73–87. Third palpomere with 2–3 sensilla clavata, fourth palpomere with 1 sensillum clavatum. Coronal suture nearly complete, 59–75 µm long.

Thorax ( Fig. 45 C ). Median antepronotal lobes well developed, and 1–2 lateral setae. Dorsocentrals 6, acrostichals 2, prealars 2–4, supraalar seta absent. Scutellum with 4–8 setae.

Wing ( Fig. 45 A ). VR 1.25–1.36. Anal lobe well developed. Costal extension 11–50 µm long with false vein extending 103–114 µm from apex of R 4+5. R 4+5 ending distal to apex of M 3+4; Cu 1 sinuate. Brachiolum with 1 seta, costa between FR and apex of R 4+5 with 17–23 setae, costal extension with 0–7 setae, R with 6–7, R 1 with 2–3, R 4+5 with 7– 10 setae, other veins bare.

Legs. Spur of front tibia 25–27 µm long, spurs of middle tibia 18–19 µm and 16–17 µm long, of hind tibia 30–34 µm and 14–16 µm long. Width at apex of front tibia and mid tibia each 23–26 µm, of hind tibia 29–32 µm. Comb of 11 setae, 18–32 µm long. Lengths and proportions of legs as in Table 25.

Abdomen. Tergite I with 10 setae, T II–VIII each with about 16 setae. Sternite I bare, S V–VII each with about 8–10 setae, S VIII with 28 setae.

Genitalia ( Fig.45 D–H ). Gonocoxite with 5–7 setae, including 2–3 strong and 2–5 weak setae. Tergite IX divided, with 18–20 setae. Segment X with sharply triangular outer corners. Cercus 71–80 µm long. Apodeme against gonocoxite 69–87 µm long. Seminal capsule dark, ovoid; 59–69 µm long, excluding neck, 39–43 µm wide, with rather strong and short microtrichia about 7 µm long. Notum 80–91 µm long.

Pupa (n = 5)

Total length 2.20–2.88, 2.58 mm. Exuviae with yellowish tinge, especially on margins of wing sheath and of genital sheath.

Cephalothorax. Frontal setae absent. Larger precorneals, ventral median antepronotal and Dc 4 about 45–50 µm long. Shorter precorneal, dorsal median antepronotal, lateral antepronotal (apparently only 1), and postorbitals all about 25–35 µm long. Dc 1, Dc 2 and Dc 3 about 15–20 µm long. Distance between Dc 1 and Dc 2 48–66, 57? µm; between Dc 2 and Dc 3 1–5, 3 µm; between Dc 3 and Dc 4 5–7, 6 µm.

Abdomen. Tergite I with anterolateral shagreen; T II–IX with strong even shagreen on whole segments, no bare preapical band on VIII, but with larger fenestrae. Sternites I–II bare or with very faint, pale anterolateral spinules on S I, S III with few posterior spinules, S IV with more extensive posterior spinules, S V with anterolateral spinules and posterior band of spinules, S VI with broad anterior band and narrow posterior band of spinules, S VII with spinules over most of segment except anteromedian and caudolateral regions, S VIII with spinules in anterior half except medially, S IX with anterolateral spinules. Tergal conjunctive II/III with 0–8, 4 spinules; III/IV with 17–28, 23; IV/V with 17–39, 29; V/VI with 32–53, 41; VI/VII with 23–47, 39 spinules. Sternal conjunctive III/IV with 0–12, 3 spinules; IV/V with 18–77, 56; V/VI with 64–83, 74; VI/VII with 36–103, 71; VII/VIII with 16–33, 23 spinules. Anal segment without setae. Female genital sac rugulose.

Fourth instar larva (n = 5–7 except when otherwise stated)

Total length 2.66–4.37, 3.74 mm. Head capsule length 0.23–0.25, 0.26 mm. Head capsule light brown, thorax with reddish brown spots, abdomen brownish violet, fat body grayish blue.

Head. Antenna as in Fig. 45 J . Length of antennal segments (in µm): 6.5–10, 8; 2.5–4, 3; 1.5–2, 2; 2–2.5, 2.5. AR 1.00–1.29, 1.08. Basal antennal segment 11.5–13, 12.5 µm m wide; blade 7–9, 8 µm long; accessory blade 5–6.5, 5.5 µm long. Sensilla basiconica 2.5–4, 3.5 µm (4) long. Subapical style of second segment 3.5–5.5, 4.5 µm long. Labrum and epipharyngeal area as in Fig. 40 J . Premandible ( Fig. 45 K ) 53–59, 56 µm long. Mandible ( Fig. 45 L ) 89–119, 100 µm long; with 3 inner teeth; seta subdentalis not measurable; seta interna absent. Mentum as in Fig. 45 I , with 4–5 pairs of lateral teeth; median tooth 25–30, 27 µm (4) wide, ventromental plate 7–9 µm wide in flattened mentum. Postmentum 70–85, 78 µm long.

Abdomen. Anterior parapods 75–110, 91 µm long, nearly completely fused along their length; each with about 30 longer weakly serrated claws. Posterior parapods 69–75 µm (3) long; each with 7–9, 8 claws, each 30–34, 33 µm long. Dorsal anal tubules 50 µm (2) long, 25–30 (3) µm wide. Ventral anal tubules 46–64 µm (2) long, 59–41 µm (2) wide.

Third instar larva (n = 2–6, as indicated)

Total length 1.80–3.16, 2.69 mm (5). Head capsule length 0.16–0.22, 0.19 mm (6).

Head. Length of antennal segments (in µm, n = 2): 5.5–7; 2.5–3.5; 2; 2. AR 0.75–1.00 (2). Basal antennal segment 9–13.5, 11 µm (4) wide, blade 9–9.5 µm (3) long, accessory blade 5.5 µm (1) long; Premandible 39 µm (1) long. Mandible 62–82, 75 µm (6) long. Postmentum 48–66, 57 µm (6) long.

Abdomen. Anterior parapods 46 µm (1) long. Posterior parapods 48 µm (1) long; with 7–10 (2) claws, each 21– 25, 24 µm (4) long. Anal tubules 25–59 µm (2) long, 21–25 µm wide.

Remarks

The larvae described here fit the description by Strenzke (1950) but none are part of the type material and thus only tentatively associated. The larvae of the type material were misidentified second or possibly third instars of A. arenarius .

Ecology and distribution

The larvae live on submersed moss in the littoral region of lakes near their borders with streams. This obligate parthenogenetic species has been found in Germany, and if the assumed associations are correct, it also occurs in Norway and Greenland. There also are records from Austria, Estonia, The Netherlands and Russia ( Saether & Spies 2004) which are in need of confirmation.

Figures

FIGURE 40. Hydrosmittia setavena (Saether) comb. n., male. A—wing; B—head; C—third palpomere; D—cibarial pump and stipes; E—virga; F—hypopygium, left dorsal aspect, right ventral aspect.

FIGURE 45. Hydrosmittia virgo (Strenzke) comb. n., female, larva. A—wing; B—female antenna; C—antepronotum; D— dorsomesal lobe; E—ventrolateral lobe; F—apodeme lobe; G—genitalia, ventral view; H—genitalia, dorsal view; I—mentum; J—larval antenna; K—premandible; L—mandible.