Chironomus fittkaui, Correia, Leny Célia Da Silva & Trivinho-Strixino, Susana, 2007

Correia, Leny Célia Da Silva & Trivinho-Strixino, Susana, 2007, New species of Chironomus Meigen (Diptera: Chironomidae: Chironominae) from Brazil, Zootaxa 1504, pp. 53-68 : 65-66

publication ID	https://doi.org/ 10.5281/zenodo.177153
DOI	https://doi.org/10.5281/zenodo.6251266
persistent identifier	https://treatment.plazi.org/id/03B84253-FFEB-0C6F-FF26-4EFDFDA89E4C
treatment provided by	Plazi
scientific name	Chironomus fittkaui
status	sp. nov.

Treatment

Chironomus fittkaui View in CoL sp. n.

( Figs. 11 View FIGURES 1 – 11 , 20, 21 View FIGURES 12 – 21 , 29 View FIGURES 22 – 29 , 53–58 View FIGURES 30 – 58 )

Type material. Holotype male with pupal and larval exuviae. BRAZIL: São Paulo, Pirassununga, pisciculture tank B1 (CEPTA-IBAMA), 21.iii.2002, L. Correia ( LEA). Paratypes: 2 males with pupal and larval exuviae, 3 larvae, São Paulo, São Carlos, Mata Reservoir (Fazenda Canchim, Centro de Pesquisa de Pecuária do Sudeste, EMBRAPA), 30.x.2000, L. Correia ( LEA, MZUSP).

Etymology. Named in honor of Dr. Ernst Josef Fittkau, for his contributions to the knowledge of Neotropical Chironomidae .

Diagnostic characters. The male can be distinguished from other Neotropical Chironomus species by the following combination of characters: legs yellowish brown with apex of femur, tibia, and tarsi brown; abdomen pale brown, tergites I–V with median brownish bands, tergites VII–VIII brown; superior volsella straight with blunt apex; and gonostylus elongate with slender distal part. The pupa is similar to the pupae of most described Neotropical species, but can be distinguished on the abdominal shagreenation and the posterolateral point patches on tergites V–VI. The larva can be distinguished from other Neotropical species by the following combination of characters: head with postmentum pigmentation; antennal blade not surpassing the length of segment four; premandible with 2 dark teeth; mandible with two inner teeth; mentum with slightly incised, trifid median tooth and with fourth lateral tooth smaller than the fifth lateral; and abdomen with rather long lateral tubules and ventral tubules, which are slender in distal half.

Male (n = 3)

Length [4.6] 4.6–5.0 mm. Coloration: head yellowish brown, flagellum and maxillary palp pale brown. Thorax yellowish brown with brown mesonotal stripes (as in Fig. 2 View FIGURES 1 – 11 ). Sternum yellowish brown; scutellum yellowish; postnotum brownish, darkened in posterior portion. Abdomen, pale brown; tergites I–V with median brownish bands, tergites VII–VIII brown (as in Fig. 3 View FIGURES 1 – 11 ). Legs ( Fig. 11 View FIGURES 1 – 11 ), yellowish brown; apex of femur, tibia, and tarsi of all legs brown.

Head. Flagellum [1000] 833–1117 µm long; AR = [2.84] 2.21–2.84. Palpomere 2–5 lengths (in µm): [31] 31–40, [139] 120–154, [167] 130–167, [265] 213–265. Frontal tubercles [28] 12–28 µm long, about 2 times as long as wide. Dorsal and ventral interocular distance [93] 80–154 µm and [99] 99–160 µm, respectively. Temporal setae [27] 20–27. Clypeus with [18] 16–18 setae.

Thorax. Acrostichals [6] 6, biserial, beginning near antepronotum; dorsocentrals [10] 9–10, partly biserial; prealars [4] 4; supraalar [1] 1. Scutellum with [12] 8–14 uniserial, transversally arranged setae. Scutal tubercle low.

Wing. Length [2.09] 1.75–2.32 mm. Membrane transparent, without setae; most veins pale brown; RM brown, darker than FCu. Brachiolum with [2] 2 setae, R with [26] 18–33 setae, R1 with [23] 10–24 setae, R4+5 with [31] 11–31 setae in distal 4/5. Squama with [9] 7–9 setae. R2+3 ends halfway between R1 and R4+5. VR = [1.06] 1.04–1.06.

Legs. Mid- and hind ta1 with [8] 8–16 and [6] 6–12 sensilla chaetica, respectively. Lengths (in µm) and proportions of legs as in Table 5.

Hypopygium ( Fig. 20 View FIGURES 12 – 21 ). Anal tergal bands fully enclosing [7] 6–9 strong setae. Anal point parallel-sided. Superior volsella ( Figs. 20, 21 View FIGURES 12 – 21 ), straight, with blunt apex; basal lobe with [8] 6–9 long setae. Inferior volsella weakly clubbed, not extending beyond mid-point of gonostylus. Gonostylus elongate, [140] 140–168 µm long; distal part slender, with [4] 4–6 inner marginal setae.

Pupa (n = 3)

Length of abdomen [3.8] 3.0–4.0 mm. Exuviae pale brown.

Cephalothorax. Cephalic tubercles conical, frontal setae [25] 15–26 µm long. Thorax granulose in anteromedian dorsal region; scutal tubercle present; lateral antepronotals 2, precorneals 2, dorsocentrals 4.

Abdomen. Tergite VI with fine shagreenation more numerous near posterior margin, T VII with fine shagreenation near anterior margin, T VIII with pair of posteromedian patches of fine shagreen, T V–VI with posterolateral point patches. Conjunctives IV/V and V/VI with fine shagreenation. Hook row continuous, occupying 2/3 width of segment II. Pedes spurii B present on segment II. Pedes spurii A present on segment IV. Spur on segment VIII with 1 apical tooth ( Fig. 29 View FIGURES 22 – 29 ). Segments I–IV with 0, 3, 3, 3 L setae, respectively; segments V–VIII each with 4 taeniae. Anal lobe with 1 stout dorsal seta and about 100 taeniate fringe setae.

4th instar larva (n = 6)

Total length 8.0–11.0, 9.3 mm. Coloration: body red; head yellowish, postmentum ( Fig. 53 View FIGURES 30 – 58 ), with dark spot.

Head. Ventral head length [235] 224–239, 233 µm; head width [466] 466–521, 493 µm. Antenna ( Fig. 54 View FIGURES 30 – 58 ), [162] 150–162, 156 µm long; AR = [2.01] 1.71–2.01, 1,86; ring organ near base; antennal blade not surpassing segment four. Pecten epipharyngis ( Fig. 55 View FIGURES 30 – 58 ), simple, consisting of about 19 subequal teeth. Premandible ( Fig. 56 View FIGURES 30 – 58 ), with 2 dark teeth and well-developed brush. SI ( Fig. 57 View FIGURES 30 – 58 ), plumose. Mandible (as in Fig. 34 View FIGURES 30 – 58 ), with yellowish brown dorsal tooth; apical and two inner teeth blackish; inner margin with 3 spines. Mentum ( Fig. 58 View FIGURES 30 – 58 ), with slightly incised, trifid median tooth; and 6 pairs of blackish, lateral teeth. Ventromental plates separated by about 1/3 width of mentum, anterior margin smooth.

Abdomen. Anal tubules with median constriction; lateral tubules about 1/3 as long as 8th abdominal segment; with 2 pairs of ventral tubules, 1.0–1.8, 1.4 mm long, slender in distal 1/2.

Remarks. The most similar Neotropical males are C. anonymus , C. columbiensis , C. rincon and C. antonioi . However, C. fittkaui can be separated by the coloration of the legs and abdominal tergites; the shape of the gonostylus, which is more inflated and abruptly tapered at apex in C. antonioi ; and the length of the wing, which is shorter than in C. anonymus , C. columbiensis and C. rincon . The larvae of C. fittkaui can be distinguished from most known Neotropical species by the different shape of the postmentum pigmentation; the mandible having two inner teeth, which is also present in C. latistylus and C. detriticola ; and the ventral tubules with distal half slender, which is also present in C. oliveirai and Chironomus sp. AR 4.

Ecology. Larvae of C. fittkaui were collected from sediments in the Mata Reservoir (Fazenda Canchim - EMBRAPA, São Carlos), the Represa Velha Reservoir and from pisciculture tanks (CEPTA/IBAMA, Pirassununga). Chironomus larvae are common in the sediments in the Velha Reservoir and the pisciculture tanks ( Campos 1999). However, in the Mata Reservoir they only constitute 5–10% of the Chironomidae abundance ( Strixino & Trivinho-Strixino 1998).