Goeldichironomus pampeanus, Donato & Andersen, 2022

Donato, Mariano & Andersen, Trond, 2022, A new species of Goeldichironomus Fittkau, 1965 from Argentina (Chironomidae Chironominae), Zootaxa 5092 (1), pp. 143-150 : 144-149

Goeldichironomus pampeanus n. sp.

( Figs 1–21 )

Type material. Holotype: Male with larval and pupal exuviae, ARGEnTInA: Buenos Aires: Laguna Cuero de Zorro , 35,795°S 62,915°W, 28.iii.2013, hand net, M.C. Fuentes ( MLP) . Paratypes: 2 males with larval and pupal exuviae, same data as holotype ( MLP) ; 2 males, same data as holotype except 01.ii.2013 ( ILPLA) ; 1 male with larval and pupal exuviae, same data as holotype except 19.i.2015 ( ZMBN)

Etymology. From the indigenous language Quechua: pampa, meaning plain, referring to the lowland plains covering large areas in Argentina, Uruguay, and southern Brazil, using the Latin suffix - anus meaning belonging to.

Diagnostic characters. The species can be separated from its congeners on the combination of the following characters: male without dark markings on thorax and an evenly curved superior volsella projecting mesad; pupa with extensive shagreen on tergites II–VI, sternites with fine shagreen only without transverse bands of points, dorsal setae on tergite IX extending beyond anal lobe and basal ring of thoracic horn kidney-shaped; larva with bifid premandible, mentum with 6 pairs of lateral teeth, anterior pair of ventral tubules simple, labral sclerite 1 intact and labral sclerite 2 consolidated on the inner side.

Description. Male (n = 5–6).

Total length 4.68–5.38, 5.08 [4.68] mm. Wing length 1.90–3.20, 2.39 [1.90] mm. Total length/wing length 1.58–2.46, 2.17 [2.46], wing length/profemur length 2.20–3.27, 2.42 [2.26].

Coloration: Head brownish, thorax and abdomen mostly light green; vittae, median anepisternum, preepisternum, postnotum and foreleg brownish. Wing membrane hyaline without spots.

Antenna: AR 2.35–2.86, 2.67 [2.35]. Antennae with 11 flagellomeres, ultimate flagellomere 828–1041, 951 [828] μm long.

Head: Tentorium 92–190, 143 [120] μm long, 42–70, 54 [46] μm wide. Temporal setae 32–42, 37 [32]. Clypeus with 10–16, 14 [12] setae. Palpomere lengths (in μm): 28–60, 45 [34]; 40–60, 49 [40]; 86–110, 100 [90]; 108–136, 120 [108]; 160–188, 178 [160]. Third palpomere with subapical group of 6–7 sensilla arising from pit, sensilla about 20 μm long.

Thorax: Antepronotum with 4–9, 7 [5] setae; acrostichals 15–22, 20 [15]; dorsocentrals 9–19, 14 [9]; prealars 6 [6]. Scutellum with 7–10, 8 [8] setae.

Wing ( Fig. 1 ). VR 1.1–1.15, 1.12 [1.15]. Brachiolum with 1 seta, R with 14–23, 20 [16] setae; R 1 with 4–18, 13 [15] setae; R 4+5 with 7–22, 18 [22] setae. Squama with 6–10, 7 [6] setae.

Legs: Apex of fore tibia as in figure 2. Spurs of midtibia 40–60 [40] μm and 44–62 [44] μm long; spurs of hind tibia 46–56 [46] μm and 54–84 [54] μm long. Width at apex of fore tibia 80–92, 87 [80] μm; of midd tibia 82–100, 91 [82] μm; of hind tibia 82–100, 97 [82] μm. Lengths and proportion of legs in Table 1 .

Hypopygium ( Figs 3–4 ). Anal point parallel-sided, 114–130, 125 [116] μm long. Tergite IX with 25–28, 27 [25] setae. Laterosternite IX with 3–5, 4 [4] setae. Phallapodeme 124–150, 138 [144] μm long; transverse sternapodeme 64–100, 81 [64] μm long. Superior volsella evenly curved, projecting mesad. Inferior volsella digitiform, a few of the setae subapically are split. Gonocoxite 162–208, 186 [162] μm long. Gonostylus 170–222, 192 [179] μm long, abruptly narrowing subapically, with rows of weak, split setae along inner margin subapically. HR 0.88–1.12, 0.97 [1.07]; HV 2.42–2.85, 2.65 [2.75].

Pupa (n = 4).

Total length 5.26–6.28, 5.87 [5.26] mm. General coloration pale brown.

Cephalothorax: Frontal apotome ( Figs 5 , 18 ) with short cephalic tubercules; frontal setae inserted subapically. Scar of thoracic horn kidney-shaped ( Fig. 6 ). Precorneals 2, 26–94, 59 [26] μm long; lateral antepronotals 2, median antepronotals 1. Dorsocentrals 4, 50–60, 55 [50] μm long, distance between Dc 1 and Dc 2 14–24, 18 [14] μm; between Dc 2 and Dc 3 186–208, 198 [188] μm; between Dc 3 and Dc 4 12–30, 22 [24] μm.

Abdomen ( Figs 7–8 ). Tergite I with two small, median patches of fine shagreen; tergites II–VI with extensive shagreen; tergites VII–VIII and anal lobe with anterior patches of fine shagreen. Sternites II–VIII with fine shagreen. Posterior margin of tergite II with transverse row of 71–85 [71] hooklets. Pedes spurii B present on segment II; pedes spurii A present on sternite IV. Posterolateral corners of paratergites V–VI with patches of small, inconspicuous spines. Caudolateral comb on tergite VIII ( Figs 9 , 19 ) with 2–4 stronger spurs and additional small basal spurs. Segments II–IV with 3 fine L setae, segments V–VII with 4 taeniate L setae, segment VIII with 5 taeniate L setae. Anal lobe 224–320, 261 [320] μm long; with 110–149, 132 [110] taenia. Anal macrosetae 168–220, 195 [202] μm long. Genital sac 112–154, 138 [148] μm long.

Fourth instar larva (n = 3 except when otherwise stated).

Head ( Figs 10–16 , 20 ). Total length 584–623 [605] μm; cephalic capsule 316–363 [363] μm long. Postmentum 88–102 [88] μm long. Labral sclerite 1 intact, labral sclerite 2 consolidated on inner side. Mandible 180–194 [194] μm long; seta interna with 3 branches. Pecten epipharyngis with 13 (1) teeth. Premandible with 2 teeth. Mentum with median tooth crenate, with 6 pairs of lateral teeth, 2 nd lateral tooth partially fused to 1 st lateral tooth. Length of antennal segments (in μm): 62–68 [62]; 22–26 [24]; 18–22 [22]; 14–16 [14]; 6–8 [6]. AR 0.94–1.06 [0.94].

Abdomen ( Figs 17 , 21 ) With 2 pairs of ventral tubules on segment VIII, about 260 (1) μm long, anterior pair of ventral tubules simple; anal tubules short, about 130 (1) μm long.

Figures

FIGURES 1–4. Goeldichironomus pampeanus n. sp., male. 1—wing. 2—apex of fore tibia. 3—hypopygium, dorsal aspect. 4—Hypopygium, ventral aspect.

FIGURES 5–9. Goeldichironomus pampeanus n. sp., pupa. 5—frontal apotome. 6—basal ring of thoracic horn. 7—tergites I–VI. 8—tergites VII–VIII and anal lobe (fringe not drawn). 9—anal comb on tergite VIII.

FIGURES 10–17. Goeldichironomus pampeanus n. sp., larva. 10—mentum. 11—antenna. 12—mandible. 13—labroepipharyngeal area. 14—premandible. 15—pecten epipharyngis. 16—head, dorsal view. 17—posterior part of abdomen.

FIGURES 18–21. Goeldichironomus pampeanus n. sp., pupa (figs 18–19) and larva (figs 20–21). 18—frontal apotome. 19— anal comb on tergite VIII. 20—mentum. 21—posterior part of abdomen.