Aquatic Insects of Michigan

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

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 µm 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 µm long. Stipes 210 µm long. Palp lengths (µm): 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 µm long; spurs of middle tibia 78 µm and 65 µm long; of hind tibia 89 µm and 74 µm long. Width of apex of front tibia 66 µm; of middle tibia 71 µm; of hind tibia 74 µm. Sensilla chaetica 8 or 9 on ta1, of each p2 and p3. Lengths (µm) 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 µm long; transverse sternapodeme 196 µm long. Gonocoxite 310 µm long. Pars ventralis 80 µm long and completely divided into two 18 µm wide lobes. Intermedian volsella 144 µm long, lateral volsella 122 µm long, median volsella 22 µm long. Gonostylus 190 µm long. HR 1.63; HV 2.84.
Pupa: (n = 1). [under contruction]

References

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