Glyptotendipes (Caulochironomus) cf. scirpi (Kieffer)

Saether, Ole A., 2011, Glyptotendipes Kieffer and Demeijerea Kruseman from Lake Winnipeg, Manitoba, Canada, with the description of four new species (Diptera: Chironomidae), Zootaxa 2760, pp. 39-52 : 50-51

Glyptotendipes (Caulochironomus) cf. scirpi (Kieffer)

( Fig. 4 C–D)

Material examined. CANADA: Manitoba, Lake Winnipeg, Pine Dock, 1 male, 31.vii. 1969.

The single male described below keys out to G.(C.) s c i r p i (Kieffer) in the keys of Contreras-Lichtenberg (2001: 425) and Goetghebuer [1937–54: 14, as G. mancunianus (Edwards) ]. It is characterized by vestigial frontal tubercles, bearded front tarsi, a ta2/ta3 of 0.95, an AR of about 4.0, black thoracic vittae and the presence of weak scarlike marks on T I–VI.

Description. Male imago (n = 1)

Total length 8.12 mm. Wing length 3.85 mm. Total length/wing length 2.11. Total length/length of profemur 2.79. Thorax with blackish vittae, median anepisternum II, preepisternum and postnotum. Scutellum brown. Halteres pale, slightly brownish. Coxa and trochanter pale brown on p l, dark brown on p2 and p3. Femora pale with darkened apices. Tibiae and ta1 light brown with darker apical half. All ta1-ta5 dark. Abdomen dark brown.

Head. AR 4.00. Temporals 36. Clypeus with 35 setae. Tentorium 210 µm long. Stipes 230 µm long. Frontal tubercles vestigial, 4 µm long, 6 µm wide. Palpomere lengths (in µm): 58, 98, 220, 220, 258.

Thorax. Antepronotum bare. Dorsocentrals 32, acrostichals about 20, prealars 8. Scutellum with 24 setae.

Wing. VR 1.03. Brachiolum with 3 setae, R with 13, R1 with 5, R4+5 with 2 setae. Squama with 36 setae.

Legs. Sensilla chaetica 10 at 0.41–0.59 of ta1 of p2, none on p3. BR of ta l on p l 6.27, of ta1 7.78, ta1/ta3 of p1 0.95. Lengths (in µm) and proportion of legs as in Table 3.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV BR p1 1380 1399 1518 690 729 621 256 1.09 1.87 1.83 6.1 p2 1518 1518 710 473 424 315 158 0.47 2.73 4.28 5.4 p3 1794 1912 1183 700 621 384 177 0.62 2.60 3.13 6.1 Abdomen ( Fig. 4 D). Scarlike impressions present but weak on T I–VI. About 0.4 times as long as tergite on T I, about 0.24 times as long as tergite on T II, about 0.18–0.21 times as long as tergite on T III–V, about as long as T VI as on T II.

Hypopygium ( Fig. 4 C). T IX with 26 setae, including about 10 to each side ventrolateraly of anal point; laterosternites IX each with 6 setae. Phallapodeme 200 µm long. Transverse sternapodeme 127 µm long. Gonocoxite 14 µm long, gonostylus 326 µm long. HR 0.96, HV 2.49.

Remarks. This species is unusual in possessing scarlike marks also on T I and II. However, the strongly reduced marks and vestigial frontal tubercles place it in the subgenus Caulochironomus . Although the rudimentary frontal tubercles and the faint marks on T I and II are not mentioned by Edwards (1929: 393), these easily can be overlooked. In the description of the male imago by Contreras-Lichtenberg (2000: 436) a page unfortunately appears to be missing. Only the leg measurements and a description of the hypopygium is given. The only significant difference with the present specimen is the slightly higher leg ratio of the front leg.

Gillespie (1974: 150) informally described three new species of Glyptotendipes (Caulochironomus) . One of these, “ G. (C.) sublettei ”, has a hypopygium similar to the present specimen and a long beard, but differs in several measurements.

Distribution. G. s c i r p i was previously known from lakes in Belarus, Britain, Finland, Germany, Hungary, Russia, Sweden and The Netherlands (Saether & Spies 2004).

Figures

FIGURE 4. Glyptotendipes spp. A. G. (G.) paulisensus sp. n., male hypopygium. B – G. (G.) sensilis sp. n., male hypopygium. C, D. G. (Caulochironomus) cf. scirpi (Kieffer); C – hypopygium; D – impression on tergites (schematic).