Doncricotopus sp.

Namayandeh, Armin & Beresford, David V., 2021, Review of the genus Doncricotopus (Orthocladiinae: Chironomidae): with the description of a new species from Canada, Journal of Natural History 55 (19 - 20), pp. 1195-1211 : 1208-1210

Doncricotopus sp.

( Figure 8 (a-d))

Material examined. 1 larva, Canada, Ontario, Bowmanville Creek , 43° 54 ʹ 22.90” N 78° 41 ʹ 12.8” W, 7 . VI. 2018, leg . Central Lake Ontario Conservation Authority, deposited at CNC; 1 larva, Canada, Ontario, Lynde Creek ; 43° 54 ʹ 42.27” N 78° 57 ʹ 52.4” W, 7 . VI. 2018, leg . Central Lake Ontario Conservation Authority , deposited at CNC .

Description

Larva (n = 2).

Length. 4.1–5.0, 4.6 mm.

Coloration of mounted and preserved specimens. Head capsule light (yellowish brown) with occipital region darker in contrast.

Head ( Figure 8 (a-d)). Head 303–305, 304 μm long, 310–326, 318 μm wide, HL/ HW = 0.99–1.0. Antenna five segmented. Fifth and third segment longer than fourth. AR 2.0. Blade 12.1 μm long, barely reaching the tip of second segment. Lauterborn organ small covering the third segment and only the base of fourth segments. Ring organ located at 1/ 5th from the base of the first segment ( Figure 8 (a)). SI–SIII simple. Pecten epipharynges with three subequal branches. Premandible 70 μm long, simple with bulging accessory teeth ( Figure 8 (b)). Mandible 114–117, 115 μm long, with 1 apical and 4 inner teeth, apical teeth 1.3 x the length of combined inner teeth. Seta subdentalis simple reaching the base of third inner teeth; seta interna with five branches ( Figure 8 (c)). Mentum 71–72, 71 μm long, 1126– 130, 128 μm wide, with very wide bifid median teeth and six pairs of lateral teeth, median teeth about 4.8 × the first laterals. Ventromental plate prominent, 57–65, 61 μm long, 10 μm wide. Cardinal beard with four setae. Posterolateral margins of mentum slightly extending beyond the base of ventromental plates ( Figure 8 (d)).

Abdomen (n = 1). Procercus well-sclerotized, 25–29, 27 μm long, 18–20, 19 μm wide, with two small tubercles and five apical setae, 226–249, 237 μm long. Posterior parapods 187 μm long, 114 μm wide; claws simple and dark.

Remarks. The larva differs from the larva of D. bicaudatus based on the size and shape of mentum and antennae. In addition to the above characters, it differs from D. nunavummiuti based on the color of the head capsule. However, it closely resembles the larva illustrated by Cranston (2010) from Lake Superior; but we could not confirm whether they belong to the same species. Exact geographical locations and measurements of the Cranston (2010) larva are not available as far as we can tell. There have been other reports of Doncricotopus from USA, e.g., by Sealock (2007) in Minnesota and by Berg and Hellenthal (1991) from Indiana, but we can not confirm these records. Based on the description given by Namayandeh and Culp (2016) it is likely that the larvae from Ontario and Alberta belong to the same species.

Distribution and Ecology. This species has a Nearctic distribution: Ontario, and likely also Alberta, Michigan, Minnesota, Indiana, and Wisconsin. The larva inhabits lotic habitats.

A key to the known adult males of Doncricotopus

1a. AR ≥ 1.6. Gonostylus with 1 megasetae ( Fig. 1 D-Saether 1981)......................................... ......................................................................................................................... D. bicaudatus Saether 1b. AR ≤ 1.6. Gonostylus with more than 1 megasetae ........................................................... 2 2a. Anal point <36 μm. Gonostylus small, outer margin curved ( Fig. 7 - Tuiskunen 1985 and Figure 1 (d))...................................................................................... D. dentatus Tuiskunen 2b. Anal point ≥ 36 μm. Gonostylus racquet-shaped and large, outer margin quadrate ( Figure 3 (b))............................................................................................ D. nunavummiuti sp. n.

A key to the known pupae of Doncricotopus

1a. Tergite III with no median spines ( Fig. 2 A-Saether 1981). Thoracic horn with pointed apex covered with spinules ( Fig. 2 C-Saether 1981).................... D. bicaudatus Saether

1b. Tergite III with cluster of few median spines ( Figure 5 (d)). Thoracic horn with curved and bare apex ( Figure 5 (b-c)).......................................................... D. nunavummiuti sp. n.

A key to the known larva of Doncricotopus

1a. Posterolateral margin of the mentum extend well-beyond seta submenti ( Figure 6 (d)). Procercus with four apical setae ( Figure 6 (e)). Head capsule dark ( Figure 7 (a))... ..................................................................................................................... D. nunavummiuti sp. n.

1b Posterolateral margins of the mentum not much extended beyond seta submenti. Procercus with five apical setae. Head capsule light ( Figure 7 (b)). ................................ 2

2a. Median tooth of mentum ≥ 4.7 × the length of first inner teeth ( Figure 8 (d)). AR ≈ 2.0................................................................ ................................................................ D. sp.

2b. Median tooth of mentum ≤ 3.8 × the length of first inner teeth ( Fig. 3 A-Saether 1981). AR ≈ 2.5.......................................................................................... D. bicaudatus Saether

Figures

Figure 1. Doncricotopus dentatus Tuiskunen, 1985, a-d adult male. a. Head; b. Antenna; c. Wing; d. Hypopygium.

Figure 2. Doncricotopus nunavummiuti sp. n., a-d adult male. a. Head; b. Antenna; c. Sensilla clavata on apex of 3rd palpomere; d. Thorax, lateral view.

Figure 3. Doncricotopus nunavummiuti sp. n., a-d adult male. a. Wing; b. Hypopygium; c. Anal point.

Figure 5. Doncricotopus nunavummiuti sp. n., a-d pupa. a. Frons; b. Thorax; c. Thoracic horn; d. Abdominal tergites, anal lobes and genital sacs; e. Sternites IV–VI.

Figure 6. Doncricotopus nunavummiuti sp. n., a-f larva. a. Antenna; b. Labro-epipharyngeal region; c. Mandible; d. Mentum; e. Procercus; f. Claws of posterior parapods.

Figure 7. Coloration contrast of Doncricotopus head capsules. a-b, larva. a. Doncricotopus nunavummiuti, paratype; b. Doncricotopus bicaudatus, holotype.

Figure 8. Doncricotopus sp. a-d, larva. a. Antenna; b. Premandible; c. Mandible; d. Mentum.