Chironomus oliveirai, 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 : 63-65

publication ID	https://doi.org/ 10.5281/zenodo.177153
DOI	https://doi.org/10.5281/zenodo.6251264
persistent identifier	https://treatment.plazi.org/id/03B84253-FFED-0C6E-FF26-4B05FAC79994
treatment provided by	Plazi
scientific name	Chironomus oliveirai
status	sp. nov.

Treatment

Chironomus oliveirai View in CoL sp. n.

( Figs. 6, 10 View FIGURES 1 – 11 , 18, 19 View FIGURES 12 – 21 , 27, 28 View FIGURES 22 – 29 , 47–52 View FIGURES 30 – 58 )

Type material. Holotype male. BRAZIL: São Paulo, Pirassununga, Nova Reservoir (Centro de Pesquisa e Treinamento em Aqüicultura - CEPTA / IBAMA), 18.iii.2002, L. Correia ( LEA). Paratypes: 2 males, 1 gynandromorphic female with pupal and larval exuviae, 7 larvae, as holotype ( LEA, MZUSP).

Etymology. Named in honor of the late Dr. Sebastião José de Oliveira, 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 tarsi, tibia and distal third of femur of foreleg dark brown, and tarsi, tibia and apex of femur of mid- and hind legs brown; abdomen pale brown with brownish posterior markings on tergites I–VI; and superior volsella comparatively stout, strongly curved. The pupa differs from other described pupae of Neotropical species by having strong spines near posterior margin of tergites IV–VI. The larva can be distinguished from other Neotropical species by the following combination of characters: postmentum with dark spot; antennal blade not surpassing segment four; premandible with 4 dark teeth; mandible with three inner teeth; mentum with trifid, slightly incised median tooth; and abdomen without lateral tubules, with 2 pairs of comparatively long ventral tubules which is slender in distal half.

Male (n = 3)

Length [5.5] 5.5–6.0 mm. Coloration: head yellowish brown, flagellum and maxillary palp pale brown. Thorax yellowish brown with brown mesonotal stripes. Sternum yellowish brown; scutellum yellowish; postnotum brownish, darkened in posterior portion (as in Fig. 2 View FIGURES 1 – 11 ). Abdomen ( Fig. 6 View FIGURES 1 – 11 ), pale brown; tergites I–VI with posterior brownish markings; tergites I and VI paler than tergites II–V. Legs ( Fig. 10 View FIGURES 1 – 11 ), yellowish brown; tarsi, tibia and distal 1/3 of femur of foreleg dark brown; apex of femur, tibia and tarsi of mid- and hind legs brown.

Head. Flagellum [1265] 1247–1281 µm long; AR = [3.04] 3.04–3.26. Palpomere 2–5 lengths (in µm): [40] 40–49, [201] 176–201, [204] 185–207, [302] 299–321. Frontal tubercles 15 µm long, about 2 times as long as wide. Dorsal and ventral interocular distance [123] 114–123 µm and [198] 191–198 µm, respectively. Temporal setae [28] 26–32. Clypeus with [16] 16–17 setae.

Thorax. Acrostichals [9] 8–11, biserial, beginning near antepronotum; dorsocentrals [10] 6–10, partly biserial; prealars 5; supraalar 1. Scutellum with 12 uniserial, transversally arranged setae. Scutal tubercle low.

Wing. Length [2.85] 2.70–2.85 mm. Membrane transparent, without setae; most veins pale brown; RM brown, darker than FCu. Brachiolum with [3] 2–3 setae, R with [37] 37–38 setae, R1 with [27] 27–32 setae, R4+5 with [31] 31–38 setae in distal 2/3. Squama with [9] 7–9 setae. R2+3 ends halfway between R1 and R4+5. VR = [1.08] 1.06–1.08.

Legs. Mid- and hind ta1 with [7] 7–8 and [7] 7–9 sensilla chaetica, respectively. Lengths and proportions of legs as in Table 4.

Hypopygium ( Fig. 18 View FIGURES 12 – 21 ). Anal tergal bands fully enclosing [15] 15 strong setae. Anal point with narrow base, apex curved ventrad. Superior volsella ( Figs. 18, 19 View FIGURES 12 – 21 ), stout, strongly curved ventromedially; basal lobe with [8] 7–8 long setae. Inferior volsella weakly clubbed, not extending beyond mid-point of gonostylus. Gonostylus elongate, [185] 185–191 µm long; distal part slender, with [5] 5–6 inner marginal setae.

Pupa (n = 1)

Length of abdomen 5.2 mm. Exuviae pale brown.

Cephalothorax. Cephalic tubercles conical, frontal setae 48 µm long. Thorax granulose in anteromedian dorsal region; scutal tubercle present; lateral antepronotals 2, precorneals 2, dorsocentrals 4. Dc1 and Dc2, 3, 4 as in Figure 24 View FIGURES 22 – 29 .

Abdomen ( Fig. 27 View FIGURES 22 – 29 ). Tergites IV–VI with strong spines near posterior margin, T VI with shagreen near anterior margin, T VII with pair of lateral patches of shagreen near anterior margin, T VIII with pair of median patches of shagreen near posterior margin. Conjunctives IV/V and V/VI with fine shagreenation. Hook row continuous, occupying 1/2 width of segment II. Pedes spurii B present on segment II. Pedes spurii A present on segment IV. Spur on segment VIII with 1 tooth ( Fig. 28 View FIGURES 22 – 29 ). Segments I–IV with 0, 3, 3, 3 L setae; segments V–VIII with 4, 4, 4, 5 taeniae, respectively. Anal lobe with 1 stout dorsal seta and about 148 taeniate fringe setae.

4th instar larva (n = 8)

Total length 10.0-12.0, 11.0 mm. Coloration: body red; head yellowish, postmentum ( Fig. 47 View FIGURES 30 – 58 ), with dark spot.

Head. Ventral head length 262–290, 273 µm; head width 463–540, 499 µm. Antenna ( Fig. 48 View FIGURES 30 – 58 ), 165–201, 187 µm long; AR = 1.30–1.65, 1.46; ring organ near base; antennal blade not surpassing mid of segment four. Pecten epipharyngis ( Fig. 49 View FIGURES 30 – 58 ), simple, consisting of about 14 subequal teeth. Premandible ( Fig. 50 View FIGURES 30 – 58 ), with 4 dark teeth and well-developed brush. SI ( Fig. 51 View FIGURES 30 – 58 ), plumose. Mandible (as in Fig. 40 View FIGURES 30 – 58 ), with yellowish brown dorsal tooth; apical and three inner teeth blackish; inner margin with 2–3 spines. Mentum ( Fig. 52 View FIGURES 30 – 58 ), with slightly incised, trifid median tooth; and 6 pairs of blackish, lateral teeth. Ventromental plates separated by about 1/4 width of mentum, anterior margin smooth.

Abdomen. Anal tubules with median constriction; without lateral tubules; with 2 pairs of ventral tubules, 0.9–1.1, 1.0 mm long, slender in distal 1/2.

Remarks. Chironomus oliveirai does not seem to be closely related to any other described Neotropical Chironomus species. The distinct superior volsella combined with the coloration of the legs and abdominal tergites will separate the male of C. oliveirai . In the pupa C. phytophilus is the most similar Neotropical species, but the pupa of C. oliveirai has strong spines near posterior margin of tergites IV–VI and a pair of lateral patches of shagreen near anterior margin of tergite VII, while C. phytophilus has strong spines near posterior margin of tergites V–VI and one single patch of fine shagreenation near anterior margin of tergite VII. In the larva C. phytophilus and Chironomus sp. AR 4 ( Reiss 1974) are the most similar Neotropical species. However, the larvae of C. oliveirai can be distinguished by the following combination of characters: postmentum with dark spot; mentum with slightly incised, trifid median tooth, which is more incised in Chironomus sp. AR 4; antennal blade not surpassing segment four, while it is surpassing segment five in C. phytophilus ; and abdomen with 2 pairs of ventral tubules which is slender in distal half, while they are not slender in distal half in C. phytophilus .

Ecology. Larvae of Chironomus oliveirai were collected from sandy sediments in two reservoirs, Represa Nova and Represa Velha, at the fishing farm station of CEPTA/IBAMA in Pirassununga, São Paulo.