Caladomyia humboldti Säwedal

Trivinho-Strixino, Susana, 2012, A systematic review of Neotropical Caladomyia Säwedal (Diptera: Chironomidae), Zootaxa 3495, pp. 1-41 : 6-11

Caladomyia humboldti Säwedal

( Figs 1–13 )

Caladomyia sp. C: Trivinho-Strixino 2011: 76.

Tanytarsini Gênero C: Trivinho-Strixino & Strixino 1995: 193.

Main data of the original description: “Wing length (0.99–1.04 mm). Frontal tubercles very short, about 2 µm. AR = 0.74–0.87. Pa 1. Scts 1–3. Brachiolum with 1–2 long setae. LR1 = 2.64–3.33, LR2 = 0.59–0.66, LR3 = 0.69–0.75. Front tibia spur about 16 µm. Middle and hind tibiae with two combs, on each comb a long spur. Anal tergite with 0 or 2 setae. Anal tergal bands Y-shaped, confluent on anterior part of tergite, fused part about 30 µm long. Anal point bars long, 31–37 µm, tips of bars branched. ALR = 50.8–56.1. AnPBR = 0.9–1.1. Anal point broad with 3–4 setae on each margin. Superior volsella elongated with 4–6 setae on dorsal part and 2–3 setae. Digitus of median length, ending about half-way between its base and median margin of superior volsella. Median volsella short, 8–9 µm, on distal part with about 3 simple lamellar setae, on anteromedian part with about 4 normal setae. Gonostylus short with apex roundedly pointed.”

Material examined. BRAZIL, SP. One male with pupal exuviae (in Euparal), Itirapina, Lagoa Dourada (21° 11’ S, 47° 55’ W), 06/x/2003 (C1–33, LEIA /UFSCar). Two males with pupal exuviae, Itirapina, Lagoa Dourada, 8/ iii/2003 (C1–32; C1–40, LEIA /UFSCar). One male, Luiz Antônio, Represa do Beija-Flor (21° 36’ S, 47° 47’ W), 23/ix/2010 (C1–34, LEIA /UFSCar). One female with pupal and larval exuviae, São Carlos, Lagoa Mayaca (21° 58’ S, 47° 53’ W), (C1–35, LEIA /UFSCar). One female, Luiz Antônio, Represa do Beija-Flor, 5/v/2011) (C1–36, LEIA /UFSCar). Two larvae in the same slide (in Hoyer), Itirapina, Represa do Lobo, (22° 15’ S, 47° 49’ W), x/1987 (C1–37, LEIA /UFSCar). One larva (in Hoyer), SP, São Carlos, Quinta da Felicidade, 1984 (C1–38, LEIA / UFSCar). All specimens collected by S. Trivinho-Strixino.

Diagnostic characters. Caladomyia humboldti differs from other species of Caladomyia by the combination of the following characters. Adult male: AR 1.0; fore leg ratio 3.3; hypopygium with anal tergite bands of Y-type, fused part 28 µm long; anal point 39 µm long with posterior ending appearing divided in three protrusions; bars stout brownish, 36 µm long; digitus short (10µm), not reaching median margin of superior volsella. Adult female. AR 0.68–0.71; wing membrane as in male; genitalia with strait GcaVIII; GcIX with 1 seta; GpVIII simple, rounded. Pupa: pupal exuviae with rugose frontal apotome, cephalic tubercle absent; TIII –V with anterior paired patches of short spines surrounded by fine shagreenation. Larva: clypeal seta S3 simple; antenna 5-segmented, placed on large pedestal with prominent lateral aliform projection; Lauterborn organs large, placed on pedicels 2 times as long as antennal segments 3–5, with proximal half sclerotized.

Description

Male (n = 4)

Dimensions. Small, length about 2.10–2.36 mm. Wing length 1.25–1.28 mm.

Coloration. Head brown, flagellum and maxillary palp pale brown. Thorax brown. Abdomen white brown with bands brown on distal margin of tergites I–IV. Legs yellow.

Head. Eyes ratio 2.7–3.1. Antennal flagellum 856–900 µm long; AR 0.90–1.10. Palpomeres 2–5 lengths: 23–37; 74–83; 80–100; 146–174 µm. Frontal tubercles short, 6.2 µm. Temporal setae 7–9, uniserial. Clypeus with 12–15 setae.

Thorax. Ac 7–9 biserial, beginning near antepronotum; Dc 4–5; Pa 1, Scts 2–3. Halteres with 3–4 setae. Wing 0.34–0.46 mm wide. VR 1.24–1.27. WW 0.27–0.32. Brachiolum with 1 seta. Legs. Fore tibia with short slender white spur. Mid and hind tibiae with two black combs, each with one spur.

Lengths and proportions as in Table 1.

fe ti ta1 ta2 ta3 ta4 ta5 LR p1 594–638 250–281 813 419 344 244 113 3.3 p2 575–650 456–481 250–294 125–137 81–94 56–62 37–50 0.6 p3 656–675 594–612 425–481 250–256 212–219 137–156 81–87 0.7–0.8 Hypopygium ( Fig. 1 ). Anal tergite 103 µm long, with 2 distal setae. Anal tergite bands Y-shaped; fused part about 27–29 µm long. Anal point 37–42 µm long, lateral margins with 3 setae; posterior ending appearing divided into three protrusions; median protrusion 6–8 µm long; AnPr 2.7–3.4. Anal point bars 34–38 µm long, placed on basis of anal point, their tips not reaching apex of anal point; AnPBR 0.8. Superior volsella subrectangular 31–35 µm wide, with 6 dorsal setae and 3 setae on anterior part of inner margin (2 dorsal, 1 ventral); posteriomedian part drawn into rounded tip, digitus 9–12 µm long, not reaching beyond posteromedian corner of superior volsella. Inferior volsella near 70 µm long. Median volsella short with 2 lamelliform and 4 simple setae. Gonostylus near 62 µm long. Hypopygium ratio 1.0–1.6.

Female (n = 2)

Dimension and coloration. Length near 1.75 mm. Wing length 1.03 mm. Coloration as in male.

Head. Eyes bare, with little dorsomedian extension. Eyes ratio 2.0. Antennal flagellum slightly longer than palp; Fm 2–5 lengths: 52–61, 46–49, 52–55, 94–116 µm. Palpomeres 2–5 lengths: 30–31, 41–42, 51–76, 104–137 µm. Frontal tubercles not discernible in slide-mounted specimens. Temporal setae 5. Clypeus with 10–15 setae.

Thorax. Ac 8–10 biserial, beginning near antepronotum; Dc 7; Pa 1; Scts 3. Scutal tubercle absent.

Wing. Width 0.33 mm. VR 1.25. Macrotrichia covering all cells and veins except M and basal third of M1+2. R 2+3 not distinct; R4+5 ends proximal of M3+4.

Legs. Fore tibia with one short spur; mid and hind tibial with two black combs, each with one spur. Lengths and proportions as in Table 2.

fe ti ta1 ta2 ta3 ta4 ta5 LR p1 406 212 556 268 219 150 81 2.62 p2 425 325 212 94 62 58 50 0.65 p3 431 406 281 150 131 87 62 0.69 Genitalia ( Fig. 2 ). Sternite VIII bearing 20 setae distributed regularly; SVIII form a large floor under anterior part of vagina; posteromedian margin of SVIII rounded. GpVIII not divided, densely covered with caudolateral microtrichia. Notum slightly longer than free rami. Notum as long as seminal capsules. Seminal capsules ovoid, near 50 µm long, without neck. Spermathecal duct very long, forming loop. GcaVIII nearly straight running, diagonally to posteromedian corner of SVIII. GcIX with 1 seta.

Pupal exuviae (n = 2).

Dimensions. Small, abdomen length about 2.5 mm. Coloration yellowish brown.

Wing sheath 815–861 µm long, with short nose.

Cephalothorax ( Fig. 3 ). Frontal seta elongate and slender, near 38 µm long; cephalic tubercle absent. Thoracic horn slender somewhat rugose, 392 µm long ( Fig. 4 ). Thorax with weak granulation close to median suture. Wing sheath with short nose. Thoracic setation on both sides: 3 precorneals (PC1–3) situated in front of basal ring; PC1 with 31 µm, shorter than PC2 and PC3 (44 µm long). Two lateral antepronotals (Laps). Four dorsocentrals (DC1–4) situated in two widely separated pairs; distance between DC1–DC3 = 312 µm.

Abdomen ( Fig. 5 ). TI bare; TII with central field of fine shagreen; TIII–V with anterior paired patches of short spines surrounded by fine shagreenation ( Fig. 6 ). TVI with anterior pair of fine pontuation. TVII and TVIII bare. Hook row continuous, occupying 1/3 width of segment II. Segment VII with posterolateral comb consisting of 5 marginal large teeth and 5–6 overlapping ventral teeth ( Fig. 7 a); comb with few teeth in female pupa ( Fig.7 b). Anal lobe well developed with complete fringe of about 30 taeniae and 2 large dorsal taeniae on each side. Segments II–IV all with 3 L setae; segments V–VI with 2 L and 1 ta setae; segment VII with 2 L and 2 ta setae; segment VIII with 5 taeniae.

4th instar larva (n = 3)

Dimensions. Small, total length 3.5 mm.

Head. Width 200–220 µm, length 288–300 µm; IC 0.69–0.73. Clypeal S3 simple, partially covered by aliform projection of the antennal pedestals. Antenna 5-segmented ( Fig. 8 ), placed on prominent pedestal, 75–90 µm long, bearing.distinct apical tooth and large aliform projection ( Fig. 9 ); basal segment (107–114 µm) longer than flagellum, with basal ring organ and small seta in proximal 1/2; segment 2 unsclerotized distally, slightly shorter than segments 3–5; Lauterborn organs (LO) large, pedicels, including LO, 100 µm long, 2 times as long as antennal segments 3–5, proximal half sclerotized. Pecten epipharyngis consisted of 3 distally serrated scales. Premandible with 3 teeth ( Fig. 11 ); brush well developed. Mandible ( Fig. 10 ) with pale dorsal tooth; apical and two inner teeth brown. Mentum ( Fig. 12 ) with pale median tooth and 5 pairs of lateral teeth brown, decreasing in size laterally. Ventromental plates close together medially.

Abdomen ( Fig. 13 ) with anal tubules, near 180 µm long, curved down. Claws of posterior parapods simple.

Remarks. The best diagnostic character for the male of C. humboldti is the shape of the anal point bars. The majority of the specimens analyzed have thorax brownish and abdomen with dark brown bands on tergites I–IV. Excepting the coloration they differ also from those originally described in presence of anal tergite setae (cf. Säwedal 1981). The shagreenation on tergites and the distribution of lateral abdominal setae are the main diagnostic charatcters for C. humboldti . The larva can be separated by the large aliform projection in the antennal pedestal.

The larvae live associated to aquatic macrophyte in many lentic reservoirs of central region of São Paulo State.

Figures

FIGURES 1 – 2. Caladomyia humboldti. 1. Male hypopygium, dorsal (left), ventral (right). 2. Female genitalia, ventral.

FIGURES 3 – 7. Caladomyia humboldti. Pupa. 3. Thorax, lateral. 4. Thoracic horn. 5. Abdominal tergites. 6. Spine patches of tergites III – V. 7. Posterolateral comb of abdominal segment VIII (a), variation (b).

FIGURES 8 – 13. Caladomyia humboldti. Larva. 8. Antenna. 9. Antennal pedestal. 10. Mandible. 11. Premandible. 12. Mentum and ventromental plate. 13. Abdomen, posterior.