Pseudosmittia trilobata (Edwards)

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 : 264-269

Pseudosmittia trilobata (Edwards)

( Figs. 100 , 101 )

Spaniotoma (Smittia) trilobata Edwards, 1929: 364 . Smittia avicularia Goetghebuer, 1950: 13 ; Saether & Ferrington, 2003: 4.? Chaetocladius hexalobus Kieffer, 1924: 395 , nomen dubium. Smittia (Pseudosmittia) trilobata (Edwards) ; Goetghebuer 1943:110. Pseudosmittia trilobata (Edwards) ; Thienemann & Krüger 1939: 157; Thienemann & Strenzke 1940 fig. 6; Strenzke 1950: 299,

1960b: 439, not Pseudosmittia trilobata ; Pinder 1978 fig. 136c, not Strenzke (= P. obtusa ); Langton & Pinder 2007: 136, fig. 70

F; Makarchenko & Makarchenko 2008: 223.

Material examined: ENGLAND: Cambridgeshire, Wicken , holotype male, 2.vii.1915, F. W. Edwards, BM 1915–261 ( BMNH) , paratypes, 1 male, 1 female, same data as holotype ( NMS, BMNH) ; Cambridgeshire, Wicken Fen , 1 male 1 female, in copula, 5.v.1977, P. H. Langton ( PHL) . GERMANY: Schleswig-Holstein, Holstein , 7 males or parts of males, 1 female, 9 pupal exuviae, 15 larvae (GP 706, 708–719) ( NMS, ZSM) ; Hamburg, Bach Nandsee , 1 male, 24.viii.1964, D. Schlee ( ZSM) ; Baden-Württemberg, Tübingen , botanical garden, 1 male, 4.vii.1975, C. Brakhaus ( ZSM) . AUSTRIA: Steiermark, Ennstal, Puterersee , holotype male of P. avicularia , H. Franz ( IRSN) . BELGIUM: West Flanders, De Panne , 1 male 1–18.iv.1932, M. Goetghebuer ( UMO) . CHINA: Inner Mongolia, Alex , 1 male, 31.vii.1987, X. Wang ( XW) .

Diagnostic characters: The male imago differs from P. obtusa in having a sharply pointed apical lamella on median volsella and inferior volsella with strongest point at apex pointing anteriorly. From P. subtrilobata it differs in having less slender volsellae and longer gonocoxite, giving a higher HR ratio. The female imago differs from other known females of the group by having a sinuate Cu 1 and 28–41 non-marginal setae on costa proximal to apex of R 4+5. The pupa has no setae on the anal segment and genital sac in both sexes but with both ventral and apical spinules. The larva appears indistinguishable from that of P. forcipata .

Male imago (n = 8–9, except when otherwise stated)

Total length 1.67–2.32, 1.88 mm. Wing length 0.95–1.32, 1.10 mm. Total length/wing length 1.65–1.87, 1.73. Wing length/length of profemur 3.05–3.31, 3.22. Coloration black with some traces of yellow on scutum.

Head ( Fig. 100 B ). AR 1.13–1.47, 1.33. Terminal flagellomere 311–486, 380 µm long. Temporal setae 3–6, 5 (5), consisting of 1–2, 2 (5) inner verticals and 2–4, 3 outer verticals. Clypeus with 4–7, 5 (5) setae. Tentorium 101– 117, 110 µm (6) long, 21–27, 25 µm (5) wide. Cibarial pump and stipes as in Fig. 100 D . Stipes 96–110, 106 µm (5) long, 27–39, 32 µm (4) wide. Palpomere lengths (in µm): 23–30, 25; 37–46, 41; 64–78, 70; 69–101, 82; 91–128, 109. Third palpomere ( Fig. 100 C ) with 2–3, 3 sensilla clavata.

Thorax. Median antepronotal lobes slightly reduced, antepronotum with 1–2, 1 (5) lateral setae. Dorsocentrals 9– 12, 10; acrostichals 2; prealars 3–4, 4. Scutellum with 4–6, 5 (6) setae.

Wing ( Fig. 100 A ). VR 1.37–1.47, 1.42. One specimen with postcubital fork, VR 2 1.40. Anal lobe small, slightly projecting. Costal extension 9–23, 19 µm long. R 4+5 ending well proximal to apex of M 3+4; Cu 1 distinctly sinuate. Brachiolum with 1 seta, other veins bare.

Legs. Spur of front tibia 37–48, 44 µm (7) long, spurs of middle tibia 16–23, 20 µm (6) and 14–22, 18 µm (6) long, of hind tibia 38–49, 42 µm (7) and 17–23, 19 µm (5) long. Width at apex of front tibia 18–30, 22 µm, of middle tibia 23–25, 24 µm, of hind tibia 27–43, 43 µm. Comb of 11–13, 12 (7) setae, shortest setae 21–27, 23 µm (7) long, longest setae 34–46, 38 µm (7) long. Lengths and proportions of legs as in Table 74.

Hypopygium ( Fig. 100 E ; Edwards 1929, fig. 7i; Thienemann & Strenzke 1940, fig. 6; Strenzke 1960b, fig. 39b). Anal point absent; tergite IX with 4–7, 5 (14) setae; laterosternite IX with 3–6, 5 (14) setae. Phallapodeme 80–107, 90 µm (14) long; transverse sternapodeme 46–64, 52 µm (14) long, no oral projections. Virga ( Fig. 100 F ) 18–30, 23 µm (13) long. Gonocoxite 123–178, 138 µm (14) long; superior volsella 32–41, 35 µm (14) long, median volsella 34–43, 40 µm (14) long, with sharply triangular lamella of somewhat variable size; inferior volsella 14–23, 19 µm (14) long, widened at apex and normally with anteriorly directed blunt to pointed tip. Gonostylus 52–64, 56 µm long; megaseta 5–9, 8 µm (13) long. HR 2.35–2.76, 2.46; HV 3.02–3.58, 3.30.

Female imago (n = 1–2)

Total length 1.39–2.05 mm. Wing length 0.85–1.15 mm. Total length/wing length 1.62–1.78. Wing length/length of profemur 2.95–3.20. Coloration of thorax yellow with dark brown vittae, preepisternum and postnotum.

Head. AR 0.39–0.45. Lengths (in µm) of flagellomeres: 61–75, 37–49, 38–50, 41–48, 85–121. Terminal flagellomere with 37 µm long strong apical seta. Temporal setae 6, including 2 inner verticals, 3–4 outer verticals and 0–1 postorbitals. Clypeus with 6–8 setae. Tentorium 98 µm long, 13 µm wide. Stipes 98 µm long, 18 µm wide. Palpomere lengths (in µm): 25–27, 34–39, 55–62, 69–82, 96–103. Third palpomere with 3 sensilla clavata, fourth palpomere with 1 sensillum clavatum. Coronal suture absent.

Thorax. Median antepronotal lobes slightly reduced, lateral setae of antepronotum 2. Dorsocentrals 11–12, acrostichals 2, prealars 4. Scutellum with 8 setae.

Wing. VR 1.35–1.39. Anal lobe as in male. Costal extension 41–71 µm long. R 4+5 ending proximal to apex of M 3+4; Cu 1 sinuate. Brachiolum with 1 seta; costa proximal to FR with 1–6 non-marginal setae, between FR and apex of R 4+5 with 27–35 non-marginal setae, costal extension with 8–9 non-marginal setae; R with 8–10, R 1 with 4–5, R 4+5 with 11–20 setae, other veins bare.

Legs. Spur of front tibia 26–34 µm long, spurs of middle tibia 16–21µm and 14–21 µm long, of hind tibia 39–48 µm and 16–21 µm long. Width at apex of front tibia 26–32 µm, of middle tibia 23–30 µm of hind tibia 34–42 µm. Comb of 14 setae, shortest setae 23–27 µm long, longest setae 39–41 µm. Lengths and proportions of legs as in Table 75.

Abdomen. Tergite I bare, T II with 16 setae, T III–VII each with 12–25, T VIII 10–15 setae. Sternite I and II bare, S III and IV each with 2–4 setae, S V–VII each with 4–9 setae, S VIII with 16––24 setae.

Genitalia ( Fig. 101 A, B ). Gonocoxite with 3–4 strong and 1–3 weak setae, with posterolateral projection. Tergite IX divided, with altogether 10–11 setae. Cercus 64–70 µm long. Apodeme against gonocoxite 66–80 µm long. Seminal capsule dark, ovoid; 66–69 µm long, 50–55 µm wide, with 16 µm long microtrichia. Notum 74–80 µm long.

Pupa (n = 7, except when otherwise stated)

Total length 1.29–2.22, 1.72. Exuviae nearly colorless, with slight yellowish tinge on margin of wing sheath.

Cephalothorax. Frontal apotome and wing sheath smooth, midscutum with or without a few spinules. Frontal seta, longer precorneals, ventral median antepronotal, lateral, postorbitals and longer dorsocentral setae all about 25– 35 µm long. Shorter dorsocentrals 15–20 µm long. Distance between Dc 1 and Dc 2 23–50, 34 µm (6), between Dc 2 and Dc 3 9–37, 22 µm, between Dc 3 and Dc 4 7–41, 21 µm.

Abdomen ( Fig. 101 C ). Tergite I bare or with very weak anterolateral spinules; T II–IX with extensive shagreen, with bare preapical band on VIII. Sternite I bare; S II–III bare or with weak anterolateral and posterior spinules; S IV– VII with anterolateral and posterior spinules, stronger on S VII; S VIII with anterolateral spinules; S IX bare except genital sac of both sexes with ventral and apicolateral spinules. Tergal conjunctive III/IV with 12–29, 18 spinules; IV/ V with 26–40, 32 (6); V/VI with 15–36, 32; VI/VII with 12–47, 32 spinules. Sternal conjunctive IV/V with 0–12, 2 spinules (present in one of two specimens); V/VI with 32–70, 42; VI/VII with 33–75, 40; VII/VIII with 16–42, 28 spinules. Anal segment without setae. Genital sac of male overreaches anal lobe by 89–96 µm (2), with both ventral and apical spinules.

Fourth instar larva (n = 10–11, except when otherwise stated)

Total length 3.24–3.71, 3.49 mm (9). Head capsule length 0.24–0.26, 0.25 mm. Head capsule pale yellow, body whitish with brownish yellow fat body.

Head. Antenna as in Fig. 101 D . Length of antennal segments (in µm): 9–13.5, 12; 3.5–5, 4; 1.5–2, 2; 2–2.5, 2. AR 1.11–1.63, 1.31. Basal antennal segment 11.5–15.5, 12 µm wide; blade 27–35, 33 µm long; accessory blade 4.5– 6.5, 5.5 µm long. Sensilla basiconica 2.5–4.5, 3 µm long. Subapical style of second segment 3.5–4.5, 3.5 µm long. Premandible ( Fig. 101 E ) 43–55, 52 µm long. Mandible ( Fig. 101 F ) 82–101, 92 µm long; with 3 inner teeth, seta subdentalis 3.5–7 µm (3) long; seta interna absent. Mentum as in Fig. 101 G , median tooth about 27 µm wide, ventromental plate 13 µm wide in flattened mentum. Postmentum 64–85, 76 µm long.

Abdomen. Anterior parapods 37–69, 53 µm (6) long, fused for most of their lengths, each with about 20 longer claws. Posterior parapods 27–39, 32 µm (7) long, each with 5 (5) claws, 7–13.5, 9 µm (5) long. Dorsal anal tubules 30– 53, 40 µm (6) long, 18–27, 23 µm (6) wide. Ventral anal tubules 41–89, 62 µm (5) long, 37–53, 43 µm (6) wide.

Third instar larva (n = 1)

Total length 3.06 mm. Head length 0.16 mm.

Head. Length of antennal segments (in µm): 11, 5, 1.5, 2.5. AR 1.20. Basal antennal segment 11 µm wide, blade slightly more than 18 µm long, accessory blade 4.5 µm long; sensilla basiconica 2.5 µm long. Subapical style of second segment 3.5 µm long. Premandible 39 µm long. Mandible 75 µm long. Postmentum 57 µm long.

Abdomen. Anterior parapods 23 µm long. Posterior parapods 25 µm long, with 5 claws. Dorsal anal tubules 27 µm long, 23 µm wide. Ventral anal tubules 34 µm long, 50 µm wide.

Second instar larva

Total length 1.36–2.09, 1.63 mm (5). Head length 0.09–0.13, 0.11 mm (5).

Head. Length of antennal segments (in µm, n = 1): 10, 4, 1.5, 2. AR 1.47 (1). Basal antennal segment 9 µm wide, blade slightly more than 14 µm (1) long, accessory blade 4.5 µm (1) long; sensilla basiconica 2.5 µm (1) long. Subapical style of second segment 2.5 µm (1) long. Premandible not measurable. Mandible 16–23 µm (5) long. Postmentum 32–42, 37 µm (5) long.

Abdomen. Anterior parapods 23 µm (1) long. Posterior parapods 18 µm (1) long, with 5 (1) claws. Dorsal anal tubules 25 µm (1) long, 18 µm (1) wide. Ventral anal tubules 30 µm (1) long, 34 µm (1) wide.

Ecology and distribution

According to Strenzke (1960b: 359) the species is euryoec but reaches its optimum in humus-rich wet meadow soil. It tolerates, however, large variations in water content and also increased salinity.

The species is known from Ireland, Austria, Belgium, Finland, France, Germany, Great Britain, Greece, Latvia, Sweden, Romania, Russia (including the Far East), Lebanon and China ( Ashe & Cranston 1990: 224, Makarchenko & Makarchenko 2008: 223), but many of the records may be of P. obtusa .

Figures

FIGURE 100. Pseudosmittia trilobata (Edwards), male. A—wing; B—head; C—third palpomere; D—cibarial pump and stipes; E—hypopygium, left dorsal aspect, right ventral aspect; F—virga.

FIGURE 101. Pseudosmittia trilobata (Edwards), female, immatures. A—female genitalia, ventral view; B—female genitalia, lateral view; C—pupa, posterior tergites; D—larval antenna; E—premandible; F—mandible: G—mentum.