Aquatic Insects of Michigan

by Ethan Bright, Museum of Zoology Insect Division and School of Natural Resources and Environment
University of Michigan

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Pseudochironomus richardsoni Malloch, 1915

Diagnosis: Male imago characterized by having about 60 dorsocentrals in 3-6 rows; thorax and abdomen almost uniformly blackish; AR 1.7-2.6; LR1 0.84-0.94; HR about 1.6; about 8-9 snesilla chaetica on each ta1 of p2 and p3; Ab9 tergite with apical notch; pars ventralis small and completely divided. Pupa is characterized with having only about 15 filamentous setae confined to the caudal half in the fringe of the anal lobe. The larva has an AR of about 1.7, the basal antennal segment about 120 Ám long, and Ant3 0.6x as long as Ant2.

    Male Imago: (n = 1). Total length 5.40 mm. Wing length 2.55 mm. Total length / length of profemus 2.12. Coloration as mentioned by Townes (1945, p.15).
      Head: AR 2.13. Temporals 51. Clypeus with 28 setae. Tentorium 200 Ám long. Stipes 210 Ám long. Palp lengths (Ám): 64, 90, 160, 202, 270.
      Thorax: Antepronotum with 6 setae. Dorsocentrals 59 in 3-6 rows, prealars 10, parascutellars 1. Scutellum with 22 setae in 2 or 3 rows. Wing. VR 1.9. Brachiolum with 3 setae, R with 15 setae, R1 with 1 seta, R4+5 with 1 seta. Squama with 39 setae. Legs. Spur of front tibia 78 Ám long; spurs of middle tibia 78 Ám and 65 Ám long; of hind tibia 89 Ám and 74 Ám long. Width of apex of front tibia 66 Ám; of middle tibia 71 Ám; of hind tibia 74 Ám. Sensilla chaetica 8 or 9 on ta1, of each p2 and p3. Lengths (Ám) and proportions of legs:

         
        femur
        tibia
        ta1
        ta2
        ta3
        ta4
        ta5
        LR
        BV
        SV
        BR
        p1
        1018)
        1288
        1159
        527
        417
        294
        153
        0.90
        2.49
        1.99
        3.25
        p2
        1153
        1251
        601
        331
        270
        184
        117
        0.48
        3.33
        4.00
        2.00
        p3
        1153
        1404
        810
        478
        393
        215
        141
        0.58
        2.75
        3.16
        2.64
      Hypopygium. Ab9 tergite without distinct projection, with 78 setae; Ant9 laterosternites with 7 setae. Phallapodeme 130 Ám long; transverse sternapodeme 196 Ám long. Gonocoxite 310 Ám long. Pars ventralis 80 Ám long and completely divided into two 18 Ám wide lobes. Intermedian volsella 144 Ám long, lateral volsella 122 Ám long, median volsella 22 Ám long. Gonostylus 190 Ám long. HR 1.63; HV 2.84.
      Pupa: (n = 1). [under contruction]

    References

      SŠther OA. 1977. Taxonomic studies on Chironomidae: Nanocladius, Pseudochironomus, and the Harnischia complex. Bulletin of the Fisheries Research Board of Canada 196. 143 p.