Allocladius arenarius (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 : 72-75

Allocladius arenarius (Strenzke) comb. n.

( Fig. 18 )

Pseudosmittia arenaria arenaria Strenzke, 1960b:414

Pseudosmittia arenaria flava Strenzke, 1960b:419 ; Saether & Ferrington, 2003: 3.

Pseudosmittia gracilis Thienemann & Strenzke 1940:33 , Goetghebuer 1942:289, Strenzke 1950:284, not Goetghebuer 1913.

Material examined: GERMANY: Lower Saxony, Wilhelmshaven, Zwischenhafen-Isliinde, Zucht Bauer , holotype female of P. arenaria arenaria on 2 slides, Ch 1239 (GP 588, 530), paratypes as holotype, 10 or parts of females, 81 pupal exuviae (GP 574–583, 589, 591) , Schleswig-Holstein, Holstein 1940/41, 26 females or parts of females, 5 pupal exuviae, 11 larvae (GP 567–572, 574, 575, 592–597, 599, 601, 603–605): Wilhelmshaven, Zucht Bauer, holotype female of P. arenaria flava on 2 slides, Ch 1238 (GP 587, 602), paratypes as holotype, 21 female or parts of females, 30 pupal exuviae (GP 573–577, 584–586, 600); Zuchten von Scholl, no other data, parts of about 25 females (GP 598)(all NMS) ; 3 pupal exuviae as P. gracilis Strenzke, Nos. 258, 273 ( ZSM). THE NETHERLANDS: Limburg, near Nederweert , bank of canal, 5° 47' E 51° 14' N, 1 female, 1 pupal exuviae, 7 larvae, 2.x.1992, H.K.M. Pillot ( UMSP, ZMBN) . TURKEY: Kars Province, W. Sarikamis, drift sample, 1 pupal exuviae, 5.viii.1985, W. Schacht ( ZSM) . CANADA: Nunavut: Bathurst Island, 1 pupal exuviae, 29.vii.1984, B. Hayes; Somerset Island, Stanwell Fletcher Lake , 2 larvae, 15.vii.1975 & 13.vi.1976, N.B. Snow ( CNC) . Yukon Territory: Caribou Creek , 1 larva, 5.vii.1972, Freshwater Institute Pipeline Project ( CNC) . USA: Alaska: Beaufort Sea, Barter Island , 1 larva, 1975, W. Ponds ( CNC) . South Carolina: Anderson County, Savannah River 4 mi below Hartwell Dam, moist bank, 1 third instar larva, 10.ix.1980, P.L. Hudson ( ZMBN) ; Georgia: Hart County, Savannah River 4 mi below Hartwell Dam, 1 pupal exuviae, 10.ix.1980, P.L. Hudson ( ZMBN) .

Diagnostic characters: The female imago may not be separable from those of A. nanseni and A. aizaiensis . These three species are separable from other known members of the group by having at most 1 seta on C between R 1 and the apex of R 4+5. The pupa can be distinguished by having anterior and posterior shagreen spinules clearly larger than median spinules, anal segment with setae, tergal conjunctive II/III bare, III/IV with 10–27 and VII/VIII with 7–63 spinules. The larva has 4 inner teeth on the mandible, 5 pairs of lateral teeth on the mentum and posterior parapods with 7–8 claws.

Female imago (including possible females of A. nanseni , n = 9–12, except when otherwise stated)

Total length 1.49–2.78, 2.08 mm (6). Wing length 0.83–1.65, 1.13 mm (21). Total length/ wing length 1.62–1.87, 1.73 (6). Wing length/length of profemur 3.43–4.17, 3.77. Coloration blackish brown with whitish halteres.

Head. AR 0.31–0.41, 0.35. Length (in µm) of flagellomeres: 57–87, 70; 32–54, 43; 32–48, 40; 32–54, 41; 55–89, 72. Flagellomeres 3–5 not flask-shaped. Temporal setae 3–6, 4 (8), including 1–2, 1 (8) inner verticals and 2–4, 3 outer verticals. Clypeus with 6–9, 7 setae. Tentorium 82–110, 101 µm (8) long, 14–23, 18 µm (6) wide. Stipes 75–110, 88 µm (7) long, 25–43, 29 µm (6) wide. Palpomere lengths (in µm): 16–27, 21; 30–43, 36; 43–59, 55; 39–64, 56; 66–110, 87. Third palpomere with 2–3, 2 lanceolate sensilla clavata at apex. Coronal suture absent to complete, when partly present in 1–2 parts, 16–18, 14 µm (4) and 7–18, 12 µm (2) long.

Thorax. Median antepronotal lobes well developed, with 1–3, 1 lateral setae. Dorsocentrals 5–11, 7 (21), acrostichals 6–15, 10 (19), prealars 2–4, 3 (20), supraalar 1 (21). Scutellum with 4–8, 5 (21) setae.

Wing ( Fig. 18 A ). VR 1.32–1.44, 1.37 (19). Anal lobe relatively well developed. Costal extension 16–34, 27 µm (19) long. R 4+5 ending slightly distal to apex of M 3+4; Cu 1 slightly sinuate. Brachiolum with 1 (21) seta; costa between FR and apex of R 4+5 with 0–1, 0 (21) setae; costal extension with 0–2, 1 (21) setae; R with 3–9, 6 (21) setae; R 1 with 0– 4, 1 (21) setae; R 4+5 with 1–10, 7 (21) setae; other veins bare.

Legs. Spur of front tibia 15–25, 21 µm long, spurs of middle tibia 14–21, 16 µm and 6–16, 12 µm long, of hind tibia 27–41, 35 µm and 11–18, 14 µm long. Width at apex of front and middle tibiae each 18–32, 26 µm, of hind tibia 27–41, 35 µm. Comb of 10–14, 12 setae, shortest seta 14–18, 17 µm long, longest seta 23–34, 30 µm long. Lengths and proportions of legs as in Table 10.

Abdomen. Tergite I with 2–9, 5 setae; T II–VI each with 6–18, 12; T VII with 13–30, 20; T VIII with 14–24, 18 (7) setae. Sternite I bare; S II with 0–4, 0 (8) setae; S III–VI each with 4–14, 8: S VII with 5–23, 10 (6); S VIII with16– 21, 18 (8) setae.

Genitalia ( Fig. 18 B ). Gonocoxite without caudal projection, with 6–12, 10 setae, including 1–3, 2 stronger and 5–9. 7 weak setae. Tergite IX divided, with caudal notch with altogether 11–22, 15 setae. Cercus 57–96, 78 µm (14) long. Apodeme against gonocoxite 59–112, 87 µm long; gonocoxite with triangular posterior projection not surpassing tergite IX. Seminal capsule pale, ovoid; 50–69, 58 µm long, excluding 14–16 µm long neck, 37–53, 43 µm wide, microtrichia not observed. Notum 78–114, 98 µm long.

Pupa (n = 14)

Total length 1.96–2.72, 2.36 mm. Exuviae tinged with yellow especially on margins of cephalothorax and anal segment.

Cephalothorax. Frontal apotome wrinkled, without warts, with frontal seta. Frontal seta, longer prealars, median antepronotals, longer lateral antepronotal and longer dorsocentral (usually Dc 2, occasionally Dc 3) all about 35–70 µm long. Shorter precorneal, shorter lateral antepronotal, postorbitals, and shorter dorsocentrals all about 20–30 µm long. Distance between Dc 1 and Dc 2 16–57, 36 µm; between Dc 2 and Dc 3 5–55, 22 µm; between Dc 3 and Dc 4 5–14, 10 µm.

Abdomen ( Fig. 18 C–E ). Tergite I bare, T II–VIII with strong anterior and posterior spinules and weaker median spinules covering most of tergite, T IX with extensive median shagreen. Sternites I–II bare or S II with a few posteromedian spinules, S III with weak median spinules, S IV with slightly stronger median spinules, S V–VIII with shagreen in anterior 2/3, S IX bare or with anterolateral shagreen. Tergal conjunctive III/IV with 10–27, 17 spinules; IV/V with 22–70, 51; V/VI with 37–102, 62; VI/VII with 30–100, 64; VII/VIII with 7–63, 25; VIII/IX with 0–6, 0 spinules. Sternal conjunctive III/IV with 0–19, 8 spinules; IV/V with 14–85, 58; V/VI with 45–112, 74; VI/VII with 35–118, 77; VII/VIII with 29–87, 56 spinules. Anal segment with basal seta about 40–50 µm long, 2–3 apical setae each about 25–40 µm long, and median seta about 40–50 µm long.

Fourth instar larva (n = 14–18, except when otherwise stated)

Total length 2.57–4.34, 3.80 mm (10). Head capsule length 0.23–0.32, 0.26 mm. Head capsule yellowish, body pale brownish violet.

Head. Length of antennal segments (in µm): 12–12.5, 11; 3.5–4.5, 4; 1.5–2, 2; 2–2.5, 2. AR 1.16–1.73, 1.38. Basal antennal segment 11.5–16.5, 13 µm wide; blade 9–11.5, 10.5 µm long; accessory blade 3.5–6.5, 5 µm long. Sensilla basiconica 2.5–3.5, 3 µm long. Subapical style of second segment 3.5–4.5, 3.5 µm long. Premandible ( Fig. 18 F ) 50–70, 56 µm long; with two inner teeth. Mandible ( Fig. 18 G ) 96–131, 105 µm long; with 4 inner teeth and 2 dorsal teeth; seta subdentalis 3–4.5, 4 µm long; seta interna absent. Mentum as in Fig. 18 H , with 5 pairs of lateral teeth, median tooth 23–31, 26 µm wide (3), ventromental plate 5–9, 6 µm (12) wide in–flattened mentum. Postmentum 78–110, 85 µm long.

Abdomen ( Fig. 18 I ). Anterior parapods 69–91, 78 µm (10) long, each with about 40 longer claws. Posterior parapods ( Fig. 26 I ) 69–91, 83 µm long, each with 7–8, 7 claws, each about 18–34, 24 µm long. Dorsal anal tubules 30–48, 41 µm long, 23–41, 32 µm (13) wide. Ventral anal tubules 53–91, 64 µm long, 41–71, 53 µm wide.

Third instar larva (n = 1–3)

Total length 1.80–3.11 mm. Head capsule length 0.18–0.22 mm.

Head. Length of antennal segments (in µm): 5.5–7, 2.5–3.5, 1–2, 1.5–2. AR 1.00–1.14. Basal antennal segment 8.5–10 µm wide, blade 10–10.5 µm long, accessory blade 4.5 µm long; sensilla basiconica 2 µm long. Subapical style of second segment 2.5–3 µm long. Premandible 39–47 µm. Mandible 67–82 µm long. Mentum of one specimen apparently with only indication of division of centre tooth to one side, giving the appearance of 4 lateral teeth on one side, 5 lateral teeth on other side; median tooth 16–21 µm wide. Ventromental plate when flattened 4.5 µm wide.

Abdomen. Posterior parapods 57–66 µm long, with 7 claws, each 16–23 µm long. Dorsal anal tubules 30–34 µm long, 21–25 µm wide. Ventral anal tubules 46–57 µm long, 30–34 µm wide.

Remarks

The females of A. arenarius apparently are not separable from those of A. nanseni and A. aizaiensis (see comments for these two species). However, additional associated material may resolve this problem. The possible Nearctic females are listed above among specimens from Delta Marsh, Manitoba. The differences between the two subspecies, A. arenarius arenarius and A. arenarius flavus , as described by Strenzke do not appear to hold for a larger series of specimens. Strenzke, however, separated the two subspecies primarily on the basis of color of eggs, brown in A. a. arenarius , and yellow in A. a. flavus.

Ecology and distribution

The species is apparently an obligate parthenogenetic species. The larva lives in wet sandy substrates, including the shores of at least brackish water bodies. Other records are from ponds, rivers and streams. The species is known from Germany, The Netherlands, Turkey, Canada and the USA, and it is likely to be much more widespread but confused with females of A. nanseni and A. aizaiensis .

Figures

FIGURE 18. Allocladius arenarius (Strenzke) comb. n. A—wing; B—female genitalia, dorsal view; C—pupa, posterior tergites; D—pupa, posterior sternites; E—larval premandible; F—larval premandible; G—larval mandible; H—mentum; I—apex of abdomen.

FIGURE 26. Allocladius azoricus (Storå) comb. n., male. A—wing; B—top of head; C—cibarial pump, tentorium and stipes; D—thorax; E—virga; F—hypopygium, left dorsal aspect, right ventral aspect.