Procladius (Psilotanypus) bellus (Loew)

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 : 36-37

Procladius (Psilotanypus) bellus (Loew)

( Figs 2 ; 3; 12 A, G; 13 A, F, H, K; 14 A, D, I, J)

Tanypus bellus Loew, 1866: 4 .

Procladius bellus (Loew) , Johannsen 1905: 132. Tanypus pusillus Loew, 1866: 5 .

Procladius adumbratus Johannsen, 1905: 132 .

Prothenthes riparius Malloch, 1915: 389 .

Procladius flavidus Kieffer, 1923: 297 .

Procladius malifero Garrett, 1925: 10 .

Procladius (Psilotanypus) bellus (Loew) , Sublette 1964: 111; Roback 1971: 162, 19., 1980: 31; Saether 1977: 48.

Material examined. CANADA: Manitoba, Lake Winnipeg, Victoria Beach, 8 males, 9.vii. & 25.vii. 1969; Pine Dock, 20 males, 10.vii. & 31, vii. 1969; 0.5 km off George Island, 1 male, 11.vii. 1969; 3 km off Grand Rapids, 1 male, 13.vii. 1969; 3 km off McCreary Island, 3 males, 15.vii. 1969; Gull Harbor, 16 males, 16.vii. 1969; Grand Rapids Government Wharf, 3 males, 28, vii. 1969; McBeth Harbor, 1 male, 30.vii. 1969; Beaver Point, 12 males, 30.vi. & 19.viii. 1971; 20 Mile Creek, 11 males, 26.viii. & 1.ix. 1971; Old Fishing Dock, 34 males, 24.vi.–8.ix. 1971; Calders Dock, 2 males, 5.viii. 1971; Hecla Island, 11 males, 27.vii.–25.viii. 1971; Beaver Creek, 28 males from emergence traps, 4 reared from larvae, 8.vi–8.viii. 1971; outer buoy of Red River, 2 males reared from larvae, 9.vii. 1969; east of Elk Island, 1 male reared from larva, 10.vii. 1969; 13 km southeast of Pearson Reef, l female reared from larva, 10.vii. 1969; north of outer buoy of Red River, 1 female reared from larva, 24.vii. 1969; South Basin, 86 larvae, 1 pupa, 4.vi–31.x. 1969; Narrows, 25 larvae, 4.vi–31.x.1969; North Basin, 6 larvae, 4.vi–31.x. 1969.

There was considerable hypopygial variation; particularly in the gonostylus and in the expression of the inner projection of the gonostylus ( Fig. 2 B, C). Although the projection is not described or illustrated in Roback (1971: 165, plate 33), it is persistently present in numerous specimens from Lake Winnipeg. However, since there are also a number of intermediate specimens, this projection is just regarded as part of the normal variation.

The female lacks setae on anepisternum II, has 7–22 setae on segment X, curved lobe of gonapophysis VIII ( Saether 1977 fig. 20 C), and about 2–6 sensilla chaetica on each ta1 of p2 and p3.

Pupa (n = 9)

Cephalothorax. Thoracic horn ( Fig.12 A) 313–393, 344 µm long; 60–96, 76 µm wide; plastron plate diameter 52–96, 69 µm; apical constriction of horn chamber 26–52, 32 µm wide; length/width of horn 3.81–5.32, 4.58; width of plastron plate /width of horn 0.66–1.04, 0.88; width of plastron plate/ width of constriction 1.73–2.55, 2.21.

Abdomen. Anal lobe ( Fig.12 G) with 19–26, 23 well developed spines along outer margin.

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

Head capsule length 580–724, 650 µm (158) [ 470–540 µm in Moore & Moore (1978)].

Head. Antenna as in Fig. 13 A, F. Length of antennal segments 1–5 (µm): 145–163, 155; 14–24, 20; 4–6, 5.5, 2–4, 3; 1–2, 1.5. AR 4.16–5.43, 4.81 [4.4–5.4 in Roback (1980), 4.9–6.2 in Moore & Moore (1978)]. Basal antennal segment 28–32, 30 µm wide; 4.77–5.33, 5.13 times as long as wide; ring organ 0.74–0.81, 0.76 from base; blade 19–31, 25 µm; accessory blade 15–20, 18 µm long. Apical style of second segment 6–10, 8 µm long. Apex of labrum as in Fig. 13 H. Mandible 136–164, 147 µm long)[ 105–120 µm in Moore & Moore (1978)], 114–148 µm in Roback (1980)]. Maxilla ( Fig.14 A) with lamelles of galea and palpifer broad and apparently undivided; maxillary palp ( Fig.14 D) 36–44, 40 µm long; 17–18, 18 µm wide; 2.00–2.44, 2.23 times as long as wide. Length of basal antennal segment/length of palp 3.58–4.31, 3.88. Hypopharyngeal pecten ( Fig.13 K) with 6–9, 6.7 (13) teeth.

Abdomen. Claws of posterior parapods with two relatively short and broad claws ( Fig. 14 I)

Distribution and ecology. The species is known from all over North America ( Roback 1971: 165) and in all kinds of waters ( Roback 1971: 165, 1974: 358; Oliver et al. 1990: 15; Spies 1999; Epler 2003, 2010; Caldwell 2009).

In Lake Winnipeg the species is less common than the four other dominant species of Procladius ( Fig. 1 ). The species is much more common in the South Basin and the Narrows than in the north ( Fig. 1 ). Adults were caught from early June to late September ( Fig.3 ) indicating two or more generations a year.

Figures

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

FIGURE 2. Procladius (Ps.) bellus (Loew), male. A — cibarial pump, tentorium and stipes of male; B, C — male hypopygium.

FIGURE 3. Procladius (Ps.) bellus (Loew). 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, vertical lines = 1 – 25 specimens, 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.