Tanytarsus caipira, Trivinho-Strixino, Susana & Strixino, Giovanni, 2007

Trivinho-Strixino, Susana & Strixino, Giovanni, 2007, A new Neotropical species of Tanytarsus van der Wulp, 1874 (Diptera: Chironomidae), with an unusual anal process, Zootaxa 1654, pp. 61-67 : 62-66

Tanytarsus caipira sp. n.

( Figs 1 –15)

Type material: Holotype male, slide-mounted in Euparal. BRAZIL: São Paulo State, São Carlos, UFSCar Campus, x.1999, S. Trivinho-Strixino. Paratypes: 4 male as holotype; 4 females, 4 pupal exuviae, 5 larvae, as holotype except slide-mounted in Euparal or Hoyer, ix–x.1999; 1 female with associated pupal exuviae, as holotype except ix.1999; 1 female pupa with associated larval exuviae, as holotype except ix.1998.

Etymology. From the indigenous Tupi language, Caa-pira, meaning a rustic provincial backwoodsman. The name is to be regarded as a noun in apposition.

Diagnostic characters. The long, forked, dorsal anal process distinguishes the male of T. caipira from all other Tanytarsus species. The process resembles the bifid anal point of Tanytarsus richardsi Glover, 1973 from Australia. However, in T. caipira it is not the anal point proper that is forked, but a process superposed over the tergite margin. The hypopygium of T. caipira also differs from that of T. richardsi by the short digitus and by the V-shaped anal tergite bands, which is T-shaped in T. richardsi . The pupa differs from other Tanytarsus species in having 2 pairs of taeniate setae on sternite VIII. The larva of T. caipira has a large Lauterborn organ placed on a short, weakly sclerotized pedicel, a feature approaching the Australian species T. richardsi , T. rosario Cranston, 2000 , T. humphreyi Cranston, 2000 , and T. K10 Cranston, 2000.

Male (n = 5)

Small, total length about 2 mm. Body color greenish in life, yellowish in alcohol. Head greenish yellow, antennal flagellum and plume yellowish, maxillary palp yellowish. Thorax greenish with yellow mesonotal stripes, scutellum and postnotum greenish.

Head. Antennal flagellomeres [738] 705–748 Μm long, AR = [0.76] 0.75–0.88. Length of palpomeres 2–5 (in Μm): [34] 32–40, [101] 96–104, [114] 104–120, [169] 160–200. Temporal setae 6–8, in single row. Clypeus with 10–12 setae.

Thorax. Acrostichals 12–14, dorsocentrals 6–8, prealar 1. Scutellum with 4 setae in single row.

Wing. Length [1.27] 1.24–1.31 mm, width [0.37] 0.36–0.38 mm; transparent with yellowish veins. FCu ending distal to RM; VR = [1.17] 1.09–1.22; C ending close to R4+5 and before M1+2. Macrotrichia present on all veins, except M and proximal half of Cu.

Legs. Foretibia with slender, pale spur; mid and hind tibia with two black combs, each bearing a single spur ( Fig. 3 ). Lengths (in Μm) and proportions of legs as in Table 1.

Hypopygium ( Figs 1–2 ). Anal tergal bands V-shaped. Posterior margin of tergite IX with 2 dorsolateral and 8 ventral setae; dorsally with prominent bare, forked, process, [49] 44–52 Μm long. Superior volsella bare, with distal margin hook-like, with 4 dorsal and 3 marginal setae. Digitus short, with rounded apex. Inferior volsella cylindrical, densely microtrichiose, bearing 4 long distal and 8 shorter dorsal setae. Median volsella short, with 6–8 short, spindle-shaped lamellae.

Female (n = 5)

Coloration as in male.

Head. Length of flagellomeres 2–5 (in Μm): 72–80, 56–60, 56–64, 104–120; AR = 0.44–0.51. Length of palpomeres 2–5 (in Μm): 28–40, 92–100, 92–108, 168–184. Temporal setae 6–8, in single row. Clypeus with 12–13 setae.

fe ti ta1 ta2 ta3

p1 [585] 585–600 [285] 270–300 [750] 735–765 [345] 345–375 [285] 285–315 p2 [609] 585–630 [480] 465–495 [285] 285–300 [132] 120–135 [90] 90–105 p3 [636] 630–645 [615] 600–630 [420] 405–445 [246] 240–270 [228] 225–240

continued.

ta4 ta5 LR BV BR p1 [225] 225 [105] 105 [2.66] 2.45–2.83 [1.69] 1.63–1.66 [3.2] 3.2 p2 [60] 60 [45] 45 [0.59] 0.58–0.62 [4.17] 4.17 [5.8] 5.8 p3 [138] 135–150 [75] 75 [0.68] 0.67–0.70 [2.43] 2.43 [7.7] 7.7 Thorax. Acrostichals 10–12, dorsocentrals 7–8, prealar 1. Scutellum with 4 setae in single row. Wing. Length 1.06–1.25 mm, width 0.38–0.41 mm. VR = 1.13–1.26. Setation as in male. Legs. Tibial spurs as in male. Lengths (in Μm) and proportions of legs as in Table 2.

fe ti ta1 ta2 ta3 ta4 ta5 LR BV BR p1 525–585 270–300 675–750 315–360 270–300 195–225 75–105 2.42–2.63 1.65–1.72 3.1 p2 525–600 420–510 195–240 105–120 75–105 45–60 45 0.40–0.53 4.09–4.22 5.3 p3 525–600 480–615 315–375 180–225 180–210 105–135 60–75 0.61–0.65 2.46–2.51 7.2 Abdomen. Yellowish green.

Genitalia ( Fig. 4 ). Sternite VIII bearing 17–18 setae in irregular transverse band; floor under vagina large. Gonocoxapodeme VIII straight, running diagonally to anteromedian corner of sternite VIII. Gonapophysis VIII simple, rounded, with weakly curved caudolateral microtrichia. Gonocoxite IX with 4–5 setae. Tergite IX with about 15 strong setae. Postgenital plate triangular. Seminal capsule ovoid, without neck. Spermathecal duct with long loop.

Pupa (n = 5)

Cephalothorax. Cephalic tubercles and frontal warts absent ( Fig. 5 ). Thoracic horn slender, 350 µm long, with few short spinules, tapering to distal point ( Fig. 6 ). Wing sheath with well developed nose. Antepronotals 2, about 60 µm long. Precorneals 3, in semi triangular pattern; Pc1 about 100 Μm long, twice as long as Pc2 and Pc3. Two pairs of dorsocentrals; Dc1 and Dc3 longer than Dc2 and Dc4; distance between Dc1/Dc2 and Dc3/Dc4 140 µm.

Abdomen ( Fig. 7 ). Abdominal exuviae 2.04–2.40 mm long. Tergite I bare, T II with median field of shagreen, T III–IV with paired longitudinal band of spines, T V–VI with paired point patches anteriorly, T VII bare, T VIII with paired anteriolateral field of fine shagreen, T IX with anterior field of shagreen. Hooklets continuous, occupying about 1/3 width of segment. Pedes spurii A absent; pedes spurii B present on segment II. Anal comb on segment VIII with 6–7 yellowish brown teeth in addition to 13–14 smaller ones ( Fig. 8 ). Abdominal setation: segments II–IV with 3 L setae, V–VI with 3 lateral taeniae, VII–VIII with 4–5 lateral taeniae. Sternite VIII with 2 pairs of taeniate setae. Anal lobe with complete fringe of c. 24–26 taeniae and 2 dorsal taeniae on each side.

4th instar larva (n = 5)

Total length 4.16–4.92 mm. Color pale red.

Head. Width 216–240 Μm, length 296–320 Μm; IC = 0.75. Clypeus with S3 simple ( Fig. 9 ). Antenna placed on short pedestal bearing single apical spur ( Figs 9–10 ); basal segment longer than flagellum, with basal ring organ and small seta in proximal 1/2; AR = 1.04–1.30; segment 2 unsclerotized distally, shorter than segment 3. Lauterborn organs large, placed on 27 Μm long pedicels. Pecten epipharyngis consisting of three indented scales. Premandible with three teeth ( Fig. 11 ). Mandible 135–152 Μm long, apical and inner teeth brown ( Fig. 12 ). Mentum with pale median tooth and brown lateral teeth ( Fig. 13 ).

Abdomen ( Fig. 14 ) with anal tubules about 224 Μm long. Posterior parapodes with large, smooth claws (Fig. 15).

Remarks. The presence of large Lauterborn organs mounted on a short pedestal may be a good character grouping T. caipira with some Australian Tanytarsus species. However, this character is also found in some Caladomyia species, like C. castelnaui Säwedal, 1981 and C. friederi Trivinho-Strixino et Strixino, 2000 . But in the Caladomyia larvae this pedestal is more strongly sclerotized in the proximal half than in the distal half, or it has annulations, characters not seen in the Tanytarsus larvae.

Figures

FIGURES 1 – 4. Tanytarsus caipira sp. n., adults. 1. Male hypopygium, left dorsal, right ventral. 2. Male hypopygium, lateral. 3. Spurs of fore, mid and hind tibiae. 4. Female genitalia. Scale: 100 Μm.

FIGURES 5 – 8. Tanytarsus caipira sp. n., pupa. 5. Frontal apotome. 6. Thorax. 7. Abdominal tergites. 8. Anal comb. Scales: Fig. 5 = 100 Μm; Figs 6 – 7 = 500 Μm; Fig. 8 = 50 Μm.

FIGURES 9 – 14. Tanytarsus caipira sp. n., larva. 9. Clypeal seta S 3 and antennal bases. 10. Antenna. 11. Premandible. 12. Mandible. 13. Mentum and ventromental plates. 14. Anal end, lateral view. 15. Claws of posterior parapods. Scales: Figs 9 – 13 = 100 Μm; Fig. 14 = 500 Μm; Fig. 15 = 50 Μm.