Parachironomus cayapo 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 : 7-10

Parachironomus cayapo Spies, Fittkau & Reiss, 1994

( Figs. 17–27 )

Material examined. Male with pupal exuviae, BRAZIL: São Paulo State, Pirassununga, Cepta Reservoir (21º55’55”S; 47º22’354”), ix/2003, S. Trivinho-Strixino. 1 male with pupal exuviae, as previous except for São Carlos (21º59’10”S; 47º52’52”W), Represa do Monjolinho, 23/iv/2002, T. Siqueira. 1 male with pupal exuviae, as previous except v/2002, L. C. S. Correia. 3 larvae, as previous. 1 larva, as previous except for Represa da Mata /Canchim Farm, 11/xi/2000, S. Trivinho-Strixino.

Diagnostic characters. The pupa and larva of P. cayapo can be differentiated by combination of the following characters. Pupa: cephalic tubercles present; posterolateral corners of segment VIII with 4–6 spines; sternite II without anterior and posterior transversal band of spines. Larva: mentum with 7th lateral tooth divided into 3 or 4 denticles clearer than others; premandible with 3 teeth decreasing gradually.

Description. Pupa (n = 3 unless otherwise stated)

Dimension. Abdomen 2.70–3.80 mm long.

Coloration. Exuviae pale brown.

Cephalothorax. Cephalic tubercles 45 (1) μm long, short, conical, apically pointed; frontal setae 38-34 (2) μm long, inserted subapically ( Fig. 17 ). Wing sheath 0.97–1.22 mm long. Thorax sparsely granulose dorsally ( Fig. 18 ); scutal tubercle weakly developed; prealar tubercle well developed; antepronotals 2, precorneals 2, dorsocentrals 4. Basal ring weakly constricted medially ( Fig. 19 ).

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-V with small spines concentrated on posteromedian area; T VI with conspicuous posteromedian patch of small spines ( Fig. 20 ). Sternites without conspicuous armature. Posterolateral corners of segment VIII with 4–6 spines ( Fig. 21 ). 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 76–108 (2) taeniae; lamelliform dorsal seta present.

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

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

Head 294–363 μm long, 256–288 μm wide; ventral length 144–175μm long. IC 0.79–0.91.

Antenna ( Fig. 22 ) 125–148 μm long, with 5 segments, basal antennal segment 74–86 μm long, with ring organ placed 28–31 μm from base. AR 1.29–1.45. Antennal blade well developed arising from apical portion of basal segment reaching the middle of 4th segment. 4th antennal segment 1.5 times as long as 3rd 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 23 . Premandible with 3 teeth decreasing gradually; brush absent ( Fig. 24 ).

Maxilla ( Fig. 25 ). Basal palp segment 18–25 μm long, 14–17 μm wide, with ring organ 8–9 μm from base.

Mandible ( Fig. 26 ) 108–120 μm long, with apical tooth and 2 triangular inner teeth brown. Seta subdentalis short, not surpassing 1st inner tooth.

Mentum ( Fig. 27 ). With one simple middle tooth and 7 pairs of lateral teeth; 7th lateral lighter-colored than all other teeth and divided into 3 or 4 denticles. Ventromental plate about 0.81–0.85 times as wide as mentum, anterior margin crenulate.

Abdomen. Procercus 1.08–1.15 (2) times as long as wide, with 7 anal setae. Anal tubules 163–200 (2) μm long. Posterior parapod with pale yellowish claws.

Remarks. The pupa of P. cayapo differs from P. longistilus and P. lupus by the presence of spines in the posterolateral corners of segment VIII, and can be separated from P. tirio by the absence of transverse spine bands on sternite II. The number of taeniae in the anal lobe allows separated P. cayapo from circum-Caribbean P. directus Dendy & Sublette, 1959 and the eastern Nearctic P. carinatus Townes. The serrated 7th lateral tooth of mentum separates the larva of P. cayapo from those of other species known from Brazil. However, the character is also seen in P. d i re c t u s and P. c a r i n a t u s ( Beck & Beck 1969; Epler 2001).

Figures

FIGURES 17 – 21. Parachironomus cayapo Spies, Fittkau & Reiss, 1994, pupa. 17. Frontal apotome. 18. Thorax. 19. Basal ring. 20. Abdomen, dorsal view. 21. Posterolateral spurs on segment VIII. Scales: Figs. 16, 20 = 100 μm; Fig. 18 = 50 μm; Figs. 17, 19 = 500 μm.

FIGURES 22 – 27. Parachironomus cayapo Spies, Fittkau & Reiss, 1994, larva. 22. Antenna. 23. Pecten epipharyngis. 24. Premandible. 25. Maxillary palp. 26. Mandible. 27. Mentum and ventromental plates. Scale: 50 μm.