Pseudochironomus

Paggi, Analía C. & Rodriguez Garay, Gretel N., 2015, The presence of species of Pseudochironomus Malloch 1915 (Diptera: Chironomidae) in watercourses of Chaco Serrano Ecoregion (Argentina, South America), Zootaxa 3957 (3), pp. 334-341 : 339-340

Pseudochironomus c.f. richardsoni Malloch

Pseudochironomus richardsoni Malloch 1915: 500 ; Saether, 1977: 66; Jacobsen 2008: 16.

Material examined. ARGENTINA, 1 larval and pupal exuvia associated, San Luis, Carolina stream, 18.i.07; Rio Grande river, 1 pupal exuvia, 16.xi.08; A. C. Paggi and A. I. Medina col. ( ILPLA).

Pupal exuvia (n = 2): The following measurements are different from the original description. Total length 5.85. Cephalotorax: Thoracic horn with longer branch about 870, maximum width about 149, shorter branch not well discernible. Precorneal setae, anterior about 112; median about 150; posterior about 76; antepronotal setae about 102–122 long; Dc1–2 and Dc 3 –4 10–12 apart, Dc3 separate 265–376 of Dc2.

Abdomen: Tergite II with 65–80 posterior hooklets. Sternite VIII with 5 caudolateral spines. Anal lobe 298–– 373 long with 14 fringe setae.

Larva (n=1): (The following measurements are different from the original description). Total length about 4.15. Length of antennal segment (µm): 77:16:10:7:4; AR = 2.1; basal antennal segment 22 wide, distance from base to ring organ 12, to basal mark of seta 20, to distal mark 55; premandible 97.44 long; mandible 179 long.

Abdomen: Procercus 41 high, 30 wide, with 8 apical setae about 331 long; supraanal setae about 50 long. Each parapod with 15 claws.

Remarks. The studied specimens share widely the diagnostic characters of P. richardsoni except the larval mentum which has 13 teeth instead of 9, and each posterior parapod with 15 claws instead of 55 of the Nearctic specimens ( Saether, 1977), these differences probably represent a geographic variation within the same species. The presence of P. richardsoni in Argentina represents a wide distribution of this species from the Neartics to the Neotropical Region.