Parachironomus tirio Spies, Fittkau & Reiss, 1994

Trivinho-Strixino, Susana, Silva, Fabio Laurindo Da & Roque, Fabio Oliveira, 2010, A new species of Parachironomus Lenz, 1921 (Diptera: Chironomidae: Chironominae), and description of immature stages of two other species from the Neotropical Region, Zootaxa 2689, pp. 1-14 : 10-13

Parachironomus tirio Spies, Fittkau & Reiss, 1994

( Figs. 28–37 )

Material examined. Male with pupal and larval exuviae, BRAZIL: São Paulo State, Luíz Antônio (21º36’23”S; 47º47’58”W), Lagoa do Diogo, 20/x/2003, M. A. Jancso. 2 females with pupal and larval exuviae, as previous except for Beija-Flor Reservoir, 1/xii/2002, S. Trivinho-Strixino.

Diagnostic characters. The pupa and larva of P. t i r i o can be separated by combination of the following characters. Pupa: cephalic tubercles present; posterolateral corners of segment VIII with spurs; sternite II with anterior and posterior transversal band of spines. Larva: mentum with 7th lateral tooth not divided, shorter than 6th lateral and clearer than others; premandible with proximal tooth shorter.

Pupa (n = 3 unless otherwise stated)

Dimension. Abdomen 2.20–2.30 (2) mm long.

Coloration. Exuviae pale brown.

Cephalothorax. Cephalic tubercles 15-23 (2) μm long, short, conical, apically pointed; frontal setae 14-22 (2) μm long, inserted subapically ( Fig. 28 ). Wing sheath 0.71–0.83 mm long. Thorax sparsely granulose dorsally; scutal tubercle weakly developed; prealar tubercle inconspicuous; antepronotals 2 (2), precorneals 2 (2), dorsocentrals 4 (2). Basal ring weakly constricted medially.

Abdomen. T I–VIII apparently without reticulation. T II with posterior row of recurved hooks on distinct posteriorly projecting flap, uninterrupted medially, occupying about 1/3 the width of 2nd tergite. T III-VI with small spines concentrated on posteromedian area ( Fig. 29 ); Sternite II with anterior and posterior transversal band of pale spines ( Fig. 30 ). Posterolateral corners of segment VIII with 2–3 pale spines ( Fig. 31 ). Pedes spurii B inconspicuous. Pedes spurii A present in segment IV, reduced to few spinules. Segments I–IV with 0, 3, 3, 3 L setae, respectively; segments V–VII all with 4 taeniae; segment VIII with 5 taeniae. Anal lobe with complete fringe of about 64–80 taeniae; lamelliform dorsal seta present.

4th instar larva (n = 2 unless otherwise stated)

Coloration. Body pale red, head yellowish. Procercus and anal setae pale brown. Posterior parapod claws pale yellowish.

Head 281–344 μm long, 269–281 μm wide; ventral length 125–144μm long. IC 0.82–0.96.

Antenna ( Fig. 32 ) 94–132 μm long, with 5 segments, basal antennal segment 52–83 μm long, with ring organ placed 14–31 μm from base. AR 1.26–1.69. Antennal blade well developed arising from apical portion of basal segment reaching the middle of 4th segment; 3rd antennal segment as long as 4th antennal segment.

Labrum. SI short, blade-like; SII blade-like, twice as long as SI; SIII seta-like; SIVa very small, 2 segmented. Pecten epipharyngis as in Figure 33 . Premandible with proximal tooth very short; brush absent ( Fig. 34 ).

Maxilla ( Fig. 35 ). Basal palp segment 20 μm long, 8–11 μm wide, with ring organ 9–11 μm from base.

Mandible ( Fig. 36 ) 95–105 μm long, with long apical tooth and 2 triangular inner teeth brownish. Seta subdentalis thin and long, surpassing 1st inner tooth.

Mentum ( Fig. 37 ). With simple, untoothed middle tooth and 7 pairs of lateral teeth; 7th lateral tooth not divided, shorter than 6th lateral and clearer than others. Ventromental plate about 0.84–0.95 times as wide as mentum, anterior margin crenulate.

Abdomen. Procercus 0.86 (1) times as long as wide, with 7 anal setae. Anal tubules 150 (1) μm long. Posterior parapod with pale yellowish claws.

Remarks. The presence of anterior and posterior transverse bands of pale spines on sternite II is sufficient to separate the pupa of P. tirio from other known Neotropical species of Parachironomus . The shape of the larval mentum with 7th lateral tooth not divided, shorter than 6th lateral and paler distinguish P. tirio from the other Neotropical Parachironomus .

Figures

FIGURES 28 – 31. Parachironomus tirio Spies, Fittkau & Reiss, 1994, pupa. 28. Frontal apotome. 29. Abdomen, dorsal view. 30. Sternite II. 31. Posterolateral spurs on segment VIII. Scales: Figs. 27, 30 = 100 μm; Figs. 28, 29 = 500 μm.

FIGURES 32 – 37. Parachironomus tirio Spies, Fittkau & Reiss, 1994, larva. 32. Antenna. 33. Pecten epipharyngis. 34. Premandible. 35. Maxillary palp. 36. Mandible. 37. Mentum and ventromental plates. Scale: 50 μm.