Hydrosmittia ruttneri (Strenzke et Thienemann) 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 : 129-134

Hydrosmittia ruttneri (Strenzke et Thienemann) comb. n.

( Figs. 46 , 47 )

Pseudosmittia ruttneri Strenzke et Thienemann, 1942: 352 ; Makarchenko & Makarchenko 2007: 309;? Schmid 1993: 179, fig.123; Makarchenko & Makarchenko 2008: 223.

Pseudosmittia brevitarsus Brundin, 1947:40 ; Saether & Ferrington, 2003: 4.

Pseudosmittia schachti Caspers et Reiss, 1989:126 ; Saether & Ferrington, 2003: 4 (holotype only).

Smittia oxoniana Edwards, 1937: 146 not Camptocladius oxonianus Edwards, 1922: 204 .

No t Pseudosmittia kurobeokasia Sasa et Okazawa sensu Saether & Ferrington, 2003: 5 (= P. oxoniana Edwards, 1922 ).

Material examined: AUSTRIA: Lower Austria, Lunz , holotype male, 1941, A. Thienemann, No. 27b (GP654)( NMS) ; allotype female, as holotype, No. 34 (GP687); paratypes, 2 males, 1 female, 8 pupal exuviae, 6 larvae, as holotype, Nos. 20, 27, 41, 617, 682 (GP684, 685, 686, 688, 689, 690, 692, 693)( NMS) ; 3 males, as holotype, marked as "Typus", but paratypes ( IRSN) . Lower Austria, Lunz, Maiergraben , no date, F. Gowin, No. 28 (GP691)( NMS) . SCOTLAND: Stirling, Central Balguhidder, Monachiebuin, NN 478242, 1 larva 9.ix.1982, I. Fozzard, BM1983–68; Grampian , Deeside , Lock Muick , 1 larva 5.x.1977, 37/299 842, P. S. Cranston ( BMNH) . NORWAY: Hordaland, Vaksdal, Ekse, Ekso River , swarming over small stones at edge of river, larvae washed off periphyton on stones, 4 males ,, 1 female, 2 pupal exuviae, 11 larvae, 17.vii., 6.xi.1984, G. Raddum, 27.vi., 14.x.1987, 8.vi.1988, Ø. A. Schnell , Hordaland, Vaksdal, Ekse, Lake Eksetjønni , 1 male, 4 females, including pair in copula, 27.vi.1987, Ø. A. Schnell ( ZMBN) ; Buskerud, Lake Heimdalsvatn , 1 male, 1.vii.1972, K. Aagaard ; Buskerud, Hol, Tuvetjønn near Tuva , 1237 m a.s.l., 1 pupal exuviae 28.vii.1993, P.H. Langton ( ZMBN) ; Hedmark, Storelvdal, Solbakken, Atna River , Malaise trap, 1 male, 24.vi.1986, K. Aagaard & O. Hansen ( VMT) ; Sør-Trøndelag, Selbu, Nea R705 at Nedre Nea Powerstation , 204 m a.s.l., N 63.15260 0 E 11.23629 0, 3males, 11.vi 2006, T. Ekrem & E. Stur ( VMT) ; Nordland, Gildeskål, Otterstranda , 1 pupal exuviae, 9 vi.1988 E. Willassen ( ZMBN) . SWEDEN: Lapland , 2 males, 1 female, as P. oxoniana det. F. W. Edwards, leg. A. Thienemann (GP680–682)( NMS) . TURKEY: Hakkari Prov., Habur-Deresi Valley , holotype male of P. schachti , 26 vi 1985, W. Schacht ( ZSM) ; Hakkari Prov., Suwari-Habil Pass S Beytise Gap, 1200 m a. s. l., 1 pupal exuviae 26.vi.1985, W. Schacht ( ZSM) . CANADA: Northwest Territories, Jean Marie Creek , 7 larvae, 8.ix.1971, 7.v.1972, Freshwater Institute Pipeline Project ( CNC) , Terren Counsel River , 3 larvae, 16.viii.1972, Freshwater Institute Project ( CNC) . Yukon Territory: Caribou Creek , 11 larvae, 10–31.viii.1972, Freshwater Institute Pipeline Project ( CNC) ; Quebec, Lake Matamec , 2 males 7 vi 1969, G. Power ( CNC) . USA: Alaska: Happy Valley Camp, Happy Valley Creek , 3 pharate males, 1 pharate female, 1 mature female pupa, 4 pupal exuviae, 3 larvae, 7.vii.1976 , U. S. Geological Survey ( ZMBN) . Michigan: Leelanau County, Lake Michigan, Grand Traverse Bay , 2 males, 27.v.1984, P. L. Hudson ( UMSP) .

Diagnostic characters: The male imago differs from other members of the Pseudosmittia complex except H. falsicostata in lacking inner vertical setae. The smaller size and male with wing length of 1.3–1.8 mm will separate it from H. falsicostata . The male imago of the species differs from other members of the group in having better developed accessory lobe of the inferior volsella, which is free at the apex. The female imago differs from other known females of the group by having 1–5 non-marginal setae on the costa between FR and the apex of vein R 4+5. The pupa is characterized by lacking frontal setae and anal macrosetae, tergal conjunctive II/III with 0–6 spinules, and sternite I with at least median shagreen. The larva has mandible with 3 inner teeth and weak seta interna, and 10–12 claws on the posterior parapods. It can be separated from H. falsicostata by having longer posterior parapods (150–200 µm long).

Male imago (n = 12–15, except when otherwise stated)

Total length 2.16–3.01, 2.58 mm. Wing length 1.25–1.76, 1.58 mm. Total length/wing length 1.58–1.81, 1.69. Wing length/length of profemur 3.23–3.65, 3.44. Coloration brownish black.

Head ( Fig. 46 B ). AR 0.44–1.37, 0.94 (20, but 16 specimens with AR of 0.8–1.1). Terminal flagellomere 198– 518, 397 µm (20) long, more or less pointed. Temporal setae 3–7, 6, consisting of 0 inner verticals and 2–7, 4 outer verticals and 0–3, 2 postorbitals. Clypeus with 4–10, 7 setae. Cibarial pump and stipes as in Fig. 46 D . Tentorium 105– 143, 127 µm long, 23–35, 27 µm wide. Stipes 98–133, 117 µm long, 27–34, 31 µm wide. Palpomere lengths (in µm): 27–39, 30; 39–59, 49; 75–103, 87; 71–96, 81; 87–117, 101. Third palpomere ( Fig. 46 C ) with 1–3, 2 lanceolate sensilla clavata.

Thorax. Median antepronotal lobes well developed, antepronotum with 1–2, 1 lateral setae. Dorsocentrals 5–10, 6 (18); acrostichals 2–3, 2 (16, but when with 3, as in 4 of 16 specimens, third much weaker than the other 2); prealars 3–6, 4; supraalar seta absent. Scutellum with 5–10, 7 setae.

Wing ( Fig. 46 A ). VR 1.17–1.29, 1.23. Anal lobe well developed, projecting. Costal extension 14–46, 25 µm long. R 4+5 ending slightly distal to apex of M 3+4; Cu 1 sinuate. Brachiolum with 1 seta, R with 1–5, 3, R 4+5 with 0–1, 0 setae, costal extension with 0–1, 0 non-marginal setae, other veins bare.

Legs. Spur of front tibia 27–43, 40 µm long, spurs of middle tibia 18–25, 21 µm and 16–21, 18 µm long, of hind tibia 34–46, 42 µm and 14–21, 18 µm long. Width at apex of front tibia 25–30, 29 µm, of middle tibia 24–32, 28 µm, of hind tibia 34–46, 40 µm. Comb of 11–18, 15 setae, shortest seta 16–23, 19 µm long, longest seta 27–39, 32 µm long. Lengths and proportions of legs as in Table 26.

Hypopygium ( Fig. 46 F ). Anal point 0–25, 6 µm (19) long; tergite IX with 9–29, 20 (20) setae; laterosternite IX with 3–7, 5 (20) setae. Phallapodeme 75–104, 90 µm (18) long; transverse sternapodeme 69–96, 82 µm (18) long, with well developed oral projections. Virga ( Fig. 46 E ) consisting of weak median plate 16–46, 25 µm (18) long and 6–30, 20 (19) lateral spinules. Gonocoxite 194–242, 217 µm (20) long; inferior volsella well developed, reaching to 0.55–0.63, 060 (18) gonocoxite length; accessory lobe well developed, with more or less free apex, and reaching to 0.70–0.79, 0.76 (18) gonocoxite length. Gonostylus without distinct heel, 80–103, 89 µm (20) long; small, triangular, preapical crista dorsalis; megaseta 9–11, 10 µm (19) long. HR 2.34–2.58, 2.48 (20), HV 2.54–3.34, 2.99.

Female imago (n = 5–7, except when otherwise stated)

Total length 1.68–2.66, 2.12 mm. Wing length 1.39–1.68, 152 mm. Total length/ wing length 1.45–1.63, 1.53. Wing length/length of profemur 3.64–4.19, 3.99. Coloration as in male.

Head. AR 0.46–0.73, 0.56 (8). Length (in µm, n = 8–9) of flagellomeres: 41–69, 63; 27–50, 41; 27–53, 42; 32– 55, 43; 82–114, 101. Temporal setae 3–6, 5 (10), all outer verticals. Clypeus with 5–11, 7 (10) setae. Tentorium 87– 121, 109 µm long, 11–18, 13 µm wide. Stipes 101–128, 112 µm m long, 25–43, 33 µm wide. Palpomere lengths (in µm, n = 9): 25–39, 29; 37–50, 41; 48–89, 68; 46–82, 66; 69–105, 94. Third palpomere with 2 lanceolate sensilla clavata. Coronal suture complete or when nearly complete 50–75, 62 µm long.

Thorax. Antepronotum with 1 lateral seta. Dorsocentrals 4–6, 5; acrostichals 2–3, 2 (but when 3 third weaker); prealars 3–5, 4 (8); supraalar seta absent. Scutellum with 4–8, 6 setae.

Wing ( Fig. 47 A ). VR 1.20–1.30, 1.24. Anal lobe well developed. Costal extension 37–69, 50 µm long. 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 1–5, 3 nonmarginal setae, costal extension with 1–3, 2 setae, R with 4–8, 6, R 1 with 1–8, 3 and R 4+5 with 5–11, 9 setae, other veins bare.

Legs. Spur of front tibia 29–37, 32 µm long, spurs of middle tibia 18–23, 20 µm and 14–19, 16 µm long, of hind tibia 34–43, 39 µm and 14–18, 16 µm long. Width at apex of front tibia 25–39, 25 µm m, of middle tibia 26–31, 29 µm, of hind tibia 34–43, 39 µm. Comb of 13–15, 14 setae, shortest seta 16–21, 19 µm long, longest seta 27–37, 32 µm long. Lengths and proportions of legs as in Table 27.

Abdomen. Tergites I–VII each with 6–28, 15 setae, tergite VIII with 16–24, 19 setae. Sternite I bare, II with 0–2, 1 setae; III with 4–5, 5; IV with 5–10, 8; VI and VII each with 8–17, 12 setae; VIII with 15–34, 23 setae.

Genitalia ( Fig. 47 B–F ). Gonocoxite not wide, without caudal elongation, with 12–20, 14 setae, including 4–8, 6 strong and 6–12, 7 medium to weak setae. Tergite IX divided, with altogether 12–23, 16 setae and microtrichia covering whole segment. Microtrichia of ventrolateral lobe shorter than usual. Cercus 64–98, 86 µm long. Apodeme against gonocoxite 62–91, 78 µm long. Seminal capsule dark, ovoid, with a few 3–5 µm (3) long microtrichia; capsule 69–98, 77 µm long, excluding 9–14, 11 µm long neck, 50–66, 57 µm wide. Notum 73–112, 96 µm long.

Pupa (n = 10, except when otherwise stated)

Total length 2.66–3.60, 3.21 mm. Exuviae tinged with brown, except anal segment and apical half of wing sheaths.

Cephalothorax. Frontal apotome wrinkled or with spinules. Frontal seta absent. Thorax with a few spinules. Longer precorneal, ventral median antepronotal, and Dc 1, Dc 3 and Dc 4 all about 60–90 µm long. Shorter precorneal, dorsal median antepronotal, lateral antepronotals, and postorbitals all about 25–45 µm long. Distance between Dc 1 and Dc 2 59–112, 77 µm (9); between Dc 2 and Dc 3 5–25, 9 µm (9); between Dc 3 and Dc 4 2–18, 6 µm.

Abdomen ( Fig. 47 G, H ). Tergite I with strong anterior shagreen, weaker posterolaterally; T II–VII with shagreen of evenly strong spinules over whole segments; T VIII with even shagreen on anterior one-half plus a few posterior spinules; T IX bare. Sternites I with shagreen varying from extensively and evenly covering whole segment, to extensive on posterior portion, to a few weak median spinules (spinules appear finer and paler than on other sternites); S II with shagreen on anterior half plus finer caudomedian spinules; S III–IV with fine anteromedian and posteromedian spinules; S VI–VII with more coarse anterior shagreen and caudomedially with spinules or bare; S VIII with coarse anterior shagreen, bare posteriorly; S IX bare or with relatively few anterior spinules slightly more numerous in female. Tergal conjunctive II/III with 0–6, 1 spinules; III/IV with 9–26, 15; IV/V with 23–35, 25 (9); V/ VI with 18–42, 28; VI/VII with 16–30, 21 spinules (but one specimen possibly without spinules). Sternal conjunctives III/IV with 0–20, 8 spinules; IV/V with 36–117, 84; V/VI with 45–120, 83; VI/VII with 30–105, 69; VII/VIII with 16– 60, 40 spinules. Anal segment without setae. Male genital sac bare, overreaching anal segment by 78–103, 87 µm.

Fourth instar larva (n = 8–10, except when otherwise stated)

Total length 3.47–4.60, 4.09 mm. Head capsule length 0.28–0.37, 0.31 mm. Head blackish brown, abdomen dark grayish violet with bluish violet fat body.

Head. Antenna as in Fig. 47 I . Length of antennal segments (in µm): 8–9.5, 8.5; 2–3.5, 2.5; 1.5–2.5, 2; 2–2.5, 2. AR 1.13–1.50, 1.34. Basal antennal segment 11–13, 12 µm wide; blade 6.5–10, 8.5 µm long; accessory blade 4.5–6.5, 5.5 µm (4) long. Sensilla basiconica 3–5.5, 4 µm (5) long. Apical style of second segment 3–5.5 µm (4) long. Labrum and epipharyngeal area as in Fig. 45 K . Premandible ( Fig. 47 J ) 48–64, 58 µm long. Mandible ( Fig. 47 L ) 87–114, 104 µm m (11) long; with 3 inner teeth, seta subdentalis 4–5.5 µm (4) long; seta interna with 4–5, 5 (4) branches, all weak. Mentum ( Fig. 47 M ) with 4 pairs of lateral teeth except one specimen with 5 teeth on one side; median tooth 25–30, 28 µm (7) wide; ventromental plate 9–13, 11 µm wide in flattened mentum. Postmentum 107–115, 112 µm long.

Abdomen. Anterior parapods fused for more than half their length, with about 40 slender, serrated claws on each parapod. Posterior parapods ( Fig. 47 N ) 149–194, 178 µm (5) long, with 10–12, 12 serrated claws 43–78, 71 µm (5) long. Dorsal anal tubules 64–94, 85 µm (4) long, 23 µm (2) wide. Ventral anal tubules 103–139 µm (3) long, 30–32 µm (3) wide. Anal seta 69–80 µm (2) long.

Third instar larva (n = 1–2)

Total length 2.83–3.20 mm. Head capsule length 0.22–0.23 mm.

Head. Length of antennal segments (in µm): 5.5–7; 2–2.5; 1.5–2; 2–2.5. AR 0.92–1.14. Basal antennal segment 8 µm wide, blade 7 µm long, accessory blade 5 µm long; sensilla basiconica 2.5 µm long. Subapical style of second segment 3.5–4.5 µm long. Premandible 39–43 µm long. Mandible 71–73 µm long. Postmentum 80–87 µm long.

Abdomen. Anterior parapods 87–91 µm long; posterior parapods 110 µm long, 11–12 claws of posterior parapods 59–62 µm long. Dorsal anal tubules 46 µm long, 16 µm wide; ventral tubules 53 µm long, 25 µm wide.

Remarks

The variation within the examined specimens is very large and it is possible that more than one species is included. The antennal ratio of the holotype of P. schachti for instance, is only 0.44, of two specimens from Happy Creek 0.55 and 0.58, and of the specimen from Lake Michigan 1.37. However the other specimens have an AR varying between 0.78 and 1.13 and the specimen from Lake Nerka, Alaska, has an AR of 1.01. The Turkish specimen also has a lower number of lateral spinules than the other specimens (6 as compared to about 10–30). The pupa shows variation in the shagreen of sternite I. However, we could not find any clear groups of strong spinules versus no spinules which purportedly should separate H. ruttneri from H. oxoniana sensu Edwards 1937 not 1922 (see for instance Langton 1991: 113). Also Strenzke (1950: 297) doubted that H. ruttneri was not conspecific with H. oxoniana sensu Edwards 1937 .

Schmid (1993) does not mention the presence of a seta interna in his description and figure of H. ruttneri . Accordingly his description may be of another species. In other details, however, his description is in accordance with that given here.

Ecology and distribution

The species is truly aquatic, living on algal growths on stones in northern and montane lakes and rivers. It is known from Austria, The Faroe Islands, Finland, Germany, Great Britain, Italy, The Netherlands, Norway including Spitzbergen, Romania, Russian Far East, Spain, Sweden, Switzerland, and Turkey ( Saether & Spies 2004), and from Canada (Yukon, Northwest Territories) and the U.S.A. (Alaska, Michigan), but most records need to be checked.

Figures

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.

FIGURE 46. Hydrosmittia ruttneri (Strenzke et Thienemann) 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 47. Hydrosmittia ruttneri (Strenzke et Thienemann) comb. n., female, immatures. A—female wing; B—ventrolateral lobe; C—dorsomesal lobe; D—apodeme lobe; E—female genitalia, ventral view; F—female genitalia, dorsal view; G—male pupa, posterior segments, lateral view; H—female pupa, posterior tergites; I—larval antenna; J—larval premandible; K— labrum and epipharynx; L—larval mandible; M—larval mentum; N—posterior end of larva.