Procladius (Holotanypus) denticulatus Sublette

Saether, Ole A., 2010, Procladius Skuse from Lake Winnipeg, Manitoba, Canada, with keys to some females and immature stages of the genus (Diptera: Chironomidae), Zootaxa 2726, pp. 34-58 : 41-43

Procladius (Holotanypus) denticulatus Sublette

( Fig. 6 A, B; 7; 12 E, K; 13 D;14 C, G, L)

Procladius denticulatus Sublette, 1964a (in part): 124.

Procladius (Procladius) denticulatus Sublette ; Roback, 1971: 189; Roback 1980: 47; Saether 1977: 48.

Material examined. CANADA: Manitoba, Lake Winnipeg, 0.5 km off George Island, 203 males, 11& 12.vii. 1969; 3 km off Grand Rapids, 24 males, 13.vii. 1969; 10 km off (Sturgeonskin point) Long Point, 73 males, 14.vii. 1969; 3 km off McCreary Island, 14 males, 15.vii. 1969; Gimli Government Wharf, 8 males, 24.vii. 1969; 3 km off George Island, 320 males, 27.vii. 1969; Grand Rapids Government Wharf, 2 males, 28.vii. 1969; McBeth Harbor, 59 males, 30.vii. 1969; Pine Dock, 1 male, 31.vii. 1969; Hnausa Government Wharf, 1 male, 8.ix. 1969; Gimli Government Wharf, 4 males, 9.ix. 1969; Old Fishing Dock, 2 males, 16.vi. & 21.vii. 1969; emergence traps: Beaver Creek, 5 males, 9.vi. –14.vii. 1971; rearings: 10 km east southeast of Pearson Reef, 1 male, 5.vi. 1969; 24 km south-southeast of Long Point, 1 male, 10.vi. 1969; east-southeast of outer buoy Red River, 1 male, 9.vi. 1969; Saskatchewan River Buoy, 1 male, 13.vii. 1969; 35 km east-northeast of Sturgeon, 1 female, 14.vii. 1969; Outer buoy of Red River, 1 female, 17.iii. 1970; north of outer buoy Red River, 1 male, 17.iii. 1970; 12 km east-northeast of Winnipeg Beach, 1 male, 17.iii. 1969; South Basin, 148 larvae, 4.vi–31.x.1969; Narrows, 54 larvae, 4.vi– 31.x.1969; North Basin, 226 larvae, 4.vi–31.x.1969.

The males all conform to the description given by Roback (1971: 189). The gonostylus ( Fig. 6 B, C) varies between resembling mostly the Minnesota population ( Roback 1971, fig. 370) and resembling the Québec population ( Roback 1971, fig. 372).

The females have 0–5 setae on anepisternum II, segment X with about 56–58 setae, and 9–14 sensilla chaetica proximally on each ta1 of p2 and p3.

Pupa (n = 10)

Cephalothorax. Thoracic horn ( Fig. 12 E) 393–577, 469 µm long; 120–188, 146 µm wide; atrial wall of thoracic horn with reticulate pattern; plastron plate diameter 90–188, 135 µm; apical constriction of horn chamber 42– 94, 70 µm wide; length/width of horn 2.60–13.73, 13.26; width of plastron plate /width of horn 0.71–1.03, 0.90; width of plastron plate/width of constriction 1.64–2.14, 1.95.

Abdomen. Spinules on T IV relatively large, not grouped ( Fig. 12 M). Anal lobe ( Fig. 12 K) with 24–32, 28 spines on outer margin; sparse row of long spines posterolaterally; spines at apex either on distinct protuberance or enlarged.

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

Head capsule length 860–1060, 949 µm (356)[790–1050µm in Moore & Moore (1978)].

Head. Antennal apex as in Fig.13 D. Lengths of antennal segments 1–5 (µm): 194–220, 211; 24–27, 25; 7–10, 8; 3–4, 4; 2–3, 2. AR 5.11–6.11, 5.60)[5.4–7.5 in Moore & Moore (1978)]. Basal antennal segment 32–41, 39 µm wide; 5.10–6.44, 5.50 times as long as wide; ring organ 0.66–0.80, 0.73 from base; blade 34–42, 38 µm; accessory blade 26–30, 29 µm long. Apical style of second segment 6–9, 8 µm long. Mandible 200–232, 217 µm long [175– 225 µm in Moore & Moore (1978), 167–200 µm in Roback (1980)]. Maxilla ( Fig. 14 C) with lamelles of palpifer and some lamelles of galea divided. Maxillary palp ( Fig. 14 G) 55–74, 62 µm long; 19–23, 21 µm wide; 2.70–3.52, 2.96 times as long as wide. Length of basal antennal segment/length of palp 2.92–3.93, 3.40. Hypopharyngeal pecten with 11–13, 13 teeth.

Abdomen. Claws of posterior parapods ( Fig. 14 L) all relatively long and slender.

Distribution and ecology. The species was previously known from Sweden (?, Roback 1971: 189), and is widespread Nearctic ( Oliver et al. 1990: 15, Spies 1999, Caldwell 2009). Procladius signatus (Zetterstedt) , which according to Roback (1971: 189) may be a senior synonym is present in Northern Europe and on the New Siberian Islands. The pupa as illustrated by Langton (1991 plate 7f) is very similar to pupa described here. The species apparently is a northern lake form. The distribution in Lake Winnipeg is shown in Fig. 1 , the emergence pattern in Fig. 7 .

Figures

FIGURE 1. Larval distribution of the five most common species of Procladius Skuse in the benthos of Lake Winnipeg.

FIGURE 6. Procladius spp., male. A, B. Procladius (H.) denticulatus Sublette; A – cibarial pump, tentorium and stipes; B – hypopygium. C – G. Procladius (H.) sublettei Roback; C—cibarial pump, tentorium and stipes; E—thorax; F, G—hypopygium.

FIGURE 7. Procladius (H.) denticulatus Sublette. Numbers of adults caught in light traps and emergence traps in 1969 and 1971, and numbers of immatures in benthic samples from June to November 1969 and in March 1970. (LT = light traps, ET = emergence traps, short vertical lines = 1 – 25 specimens, medium long lines = 26 – 50 specimens, longest vertical lines = 201 – 400 specimens, 2 = second instar larvae, 3 = third instar larvae, 4 = fourth instar larvae, P = pupae.

FIGURE 12. Procladius spp., pupae; thoracic horn (A – F), anal lobe (G – L), spinule pattern of tergite IV (M, N). A, G – Procladius (P.) bellus; B, H— Procladius (H.) freemani Sublette; C, I— Procladius (H.) culiciformis (L.); D, J— Procladius (H.) rugulosus sp. n.; E, K, M— Procladius (H.) denticulatus Sublette, F, L, N— Procladius (H.) sublettei Roback.

FIGURE 13. Procladius spp., larvae, antennal apex (A – E), antenna (F – G), labrum (H – J), and ligula, paraligula and hypopharyngeal pecten. A, F, H, K— Procladius (P.) bellus (Loew); B, I, L— Procladius (H.) freemani Sublette; C— Procladius (H.) culiciformis (L.); D— Procladius (H.) denticulatus Sublette; E, G, J, M— Procladius (H.) sublettei Roback.

FIGURE 14. Procladius spp., larvae; maxillae ventral view (A – B), dorsal view (C); maxillary palp (D – H), claws of posterior parapods (I – L). A, D, I, J— Procladius (P.) bellus (Loew); B, F, K— Procladius (H.) culiciformis; C, G, L— Procladius (H.) denticulatus Sublette; E— Procladius (H.) freemani Sublette; H— Procladius (H.) sublettei Roback.