Podonomus tehuelche, Siri, Augusto & Donato, Mariano, 2012

Siri, Augusto & Donato, Mariano, 2012, Two new species of Podonomus (Diptera: Chironomidae: Podonominae) of the Brundin’s decarthrus group from Ventania system, Argentina, Zootaxa 3548, pp. 39-54 : 41-43

Podonomus tehuelche sp. n.

Type material. Holotype: adult male with pupal exuviae, Argentina, Buenos Aires province, Sierra de la Ventana, Parque Provincial E. Torquinst, Cueva del Toro stream, 38º01’19.0’’S / 62º01’33.3’’W, 672 m a.s.l., collected on 4.xi.2011, emerged on 7.xi.2011, D-net, M. Donato, A. Siri & F. Spaccesi. Allotype: adult female from rock pool, Argentina, Buenos Aires province, Sierra de la Ventana, Parque Provincial E. Torquinst, Ventana Stream, 38º03’31.7’’S / 62º01’11.8’’W, 574 m a.s.l., 5.xi.2011, sweep net, M. Donato, A. Siri & F. Spaccesi. Paratypes: 1 adult female same data as allotype but 38º03’09.0’’S / 62º01’08.8’’W, 782 m, 21.v.2011; 1 prepupa, same data as holotype; 1 adult male with its pupal exuviae; 1 adult female with its pupal exuviae; 1 pharate female; 1 prepupa and 4 pupae mounted in the same slide, one of these is a pharate female, 1 prepupa and 1 larva mounted in the same slide and 1 prepupa same data as allotype, but D-net, M. Donato, A. Siri & F. Spaccesi.

Etymology. The specific epithet " tehuelche " is in honor of the native South American people Tehuelches, historically settled in Patagonia, and reaching south of the province of La Pampa and the Ventania system.

Diagnostic characters. The species can be separated from the other species of the Brundin’s decarthrus group by the following combination of characters. Male. Inner margin of the gonocoxite abruptly contracted close to the mid region; gonostylus with a relatively short apical lobe; the subapical lobe reduced as a triangular spine, clearly separated from the apical one and lacking the “ t ” seta; the “ p ” seta inconspicuous. Female. Antenna with 9 flagellomeres; inner margin of cercus subapically contracted; 5 long and strong apical setae on cercus; postgenital plate well developed and robust. Pupa. Atrium of plastron plate of the horn with triangular shape; the aeropyles opening in a furrow placed from the center towards the posterolateral edge of the plastron plate. Dorsal setae in the mid section of segments III–VII surrounded by a group of strong tubercles. Transverse ridge at the posterior margin of segments III–VII with 2 irregular rows of small denticles.

Description

Male (n = 2, except when otherwise stated) ( Figs 2–6 )

Total length 1.38–1.51 mm; total length / wing length 1.23 (1); wing length / profemur length 3.31 (1). Head ( Fig. 2 ). Eyes bare. Antenna ( Fig. 3 ) 510–600 [600] long; AR 0.35–0.36 [0.36]. Temporals 10–12 [10]; postorbitals 12 [12]. Clypeus with 2–3 [2] setae. Tentorium 125 [125] long. Lengths of palpomeres (1–5): 15–18 [15]; 28–30 [28]; 68 [68]; 53–57 [57]; 75–80 [80].

Thorax. Antepronotum with 1–3 [1] lateral setae; acrostichals 16–17 [16]; dorsocentrals 13–15 [15]; prealars 8 [8]; supraalar 1 [1]; scutellars 2 [2]; prescutellars 2 [2].

Wing (1) ( Fig. 4 ). Length 1.23 [1.23] mm; width 0.44 [0.44] mm; L / W = 2.78 [2.78]. VR 1.00 [1.00] (1). C extended 75 [75] beyond R4+5. Cell r1 at distal end of vein R1 80 [80] wide; cell r4+5 110 [110] wide; r1 width / r4+5 width 0.73 [0.73]. Wing membrane bare with R vein bearing 5 setae [5]. Brachiolum with 2 setae [2], squama with 2 setae [2].

Legs. Tibial spur on p1 36–40 [36] long; on p2 25 [25] and 26–33 [33] long; on p 3 30–33 [30] and 53–63 [53] long. Comb on p3 with 12 [12] spines. Lengths and proportions of legs in Table 1 .

Hypopygium ( Fig. 5 ). Setae on tergite IX, 3–4 [3]; on laterosternite 3–4 [3]. Gonocoxite 75–98 [98] long. Inner margin of gonocoxite contracted at 0.50–0.59 [0.59] from the base. Phallapodeme 30–57 [57] long; transverse sternapodeme 50 [50] (1) long. Gonostylus ( Fig. 6 ) 50 [50] long. Apical lobe on gonostylus 12–13 [12] long; subapical lobe 7 [7] long; apical seta on apical lobe (" t " seta) 13–15 [15] long. Setae " x " and " y " discernible at the base of the apical lobe. The " p " seta is present but not very conspicuous. HR 1.50–1.96 [1.96]; HV 2.76–3.02 [3.02].

Female (n = 4 except when otherwise stated) ( Figs 7–9 )

Total length 1.87–1.96 (2); total length / wing length 1.16–1.22 [1.22] (2); wing length / profemur length 3.39–3.63 [3.63] (2).

Head (3). Antenna with 9 flagellomeres ( Fig. 7 ), total length 255–298 [278]; AR 0.30–0.34 [0.30]. Temporal setae 10–12 [10], postorbitals 10–14 [14]. Clypeus with 2–3 [3] setae. Lengths of palpomeres (1–5): 13–20 [13]; 43–45 [43]; 60–65 [60]; 50–55 [50]; 68–75 [68].

Thorax. Antepronotum with 2–6 [2] lateral setae; acrostichals 18–20 [20]; dorsocentrals 16–25 [20]; prealars 8–9 [9]; supraalar 1 [1]; scutellars 4–6 [5]; prescutelars 2 [2].

Wing (3) ( Fig. 8 ). Length 1.16–1.22 [1.16] mm; width 0.49 [0.49] mm; L / W = 2.31–2.37 [2.37]. VR 0.95–0.98 [0.95]. C extended 60–75 [63] beyond R4+5. Cell r1 at distal end of vein R1 65–70 [65]; cell r4+5 140–145 [140] (2); r1 width / r4+5 width 0.46–0.48 [0.46]. R vein with 3–4 setae [3], R1 with 12–14 [12] setae; R4+5 with 10–12 [12]; M1+2 with 2–5 [2]; M3+4 with 1–4 [4] (2) setae; Cu1 with 0–1 [0]; An 0–1 [0]. Wing cell bare, except r4+5 with 2 apical setae. Brachiolum with 2 setae [2], squama with 2–3 setae [2].

Legs. Tibial spur on p1 35–40 [35] long; on p 2 20–28 [23] and 28–38 [28] long; on p 3 25–33 [25] and 53–63 [58] long. Comb on p3 with 11–13 [12] spines. Lengths and proportions of legs in Table 2 .

Genitalia ( Figs 9 a–c). Cercus 88–118 long; its inner margin contracted at 0.70–0.85 [0.72] from the base; 5 [5] large and strong setae on apex of cercus. Postgenital plate well developed and robust, 73–85 [73] long, with 4 laterobasal setae on each side. Postgenital plate length / cercus length 0.66–0.80 [0.68]. Seminal capsule 38–40 [38] long; notum 125–135 [125] (2) long; sternite VIII with the following setal pattern: 20–22 [20] setae, the more central pair longer, 85–88 [88] long, plus, a single row of 30–34 [30] strong setae at the caudal border. Gonapophysis VIII with 3 setae; tergite IX with 18–21 setae; sternite IX with 1–2 lateral setae.

Pupa (n = 5–8, except when otherwise stated) ( Figs 10–15 )

Total length 2.00–2.44 [2.21] mm.

Cephalothorax. Frontal apotome as in Fig. 10 . Thoracic horn ( Fig. 11 a–b): 248–288 [248] long; 163–200 [163] wide; L / W 1.32–1.58 [1.52]; plastron plate 176–215 [176] long; atrium 150–195 [150] long, with a narrow base and a broad apex; stalk 53–75 [73] long; plastron plate length / thoracic horn length 0.71–0.80 [0.71]. Aeropyles opening in a furrow 65–77 [65] long, from near the center toward the lateral side of the plastron plate ( Fig. 11 b).

Thoracic setation ( Fig. 12 ). Dc1 12 (1) long; Dc 2 10–12 (2) long; Dc 3 15–30 (2) long; Sa 12–18 long (2); 2 MAps 20–25 [25] long; 2 LAps, the thinner one 20–25 [20] long, the spine shaped 12–15 [15] long; 3 Precorneals. Distance between Dc1 and Dc2 = 10–13 (4); between Dc2 and Dc3 = 20–25; between Dc3 and Sa = 140–145 (3).

Abdomen (Figs 13,14). Ventral lamella on segment II vestigial. Shagreen with very short and sparse spines. Caudal border of each segment with 2 rows of tubercles. Chaetotaxy as in Figs 13 and 14 . Dorsal and ventral setae surrounded by strong tubercles. Segments VIII with 7–10 [8] and AL with 7–9 lateral wavy setae. Anal lobe ( Fig. 15 ) 182–213 [182] long; 2 anal macrosetae, 20–33 [30] and 63–85 [70] long. Male genital sac 175–185 [185] long.

Fourth-instar larva (n = 4–7, except when otherwise stated) ( Figs 16–21 )

Total length 2.83–3.13 mm. Each body segments with anterior and posterior ring of strong and long setae.

Head. Capsule dark, 243–270 long. Postmentum dark with clearest lateral borders. Antenna ( Fig. 16 ). AR 1.00–1.47; A 1 20–25 long, ring organ situated at 0.50–0.70 from base; blade 17–18 long; A 2 11–13 long; style 4–7 long; A3 4–6 long; A4 2–3 long.

Labrum ( Fig. 17 ): SI 16–18 long (2), pedestal of SI 5 long; SII 22–27 long, pedestal of SII 12–20 long; SIII 17–29 long, pedestal very short 2–3 long; SIVa 4–6 long, pedestal of SIVa 12–15 long; SIVb 7–11 long. Mandible ( Fig. 18 ) 73–82 long. A1 / Mn 1.75–1.83. Mentum ( Fig. 19 ) 50–68 wide, with 5 central teeth, of which the central one is slightly longer, plus 5 pairs of lateral teeth.

Abdomen. Procercus 100–138 long ( Fig. 20 ); L / W 1.82–2.82; with 7 setae with 2:2:2:1 disposition: 2 equal setae 25–40 long; 2 equal setae 95–120 long; 2 equal setae 190–215 long; and 1 longer seta 280–350 long. Preanal seta 93–125 long. Four rounded anal tubules are present. Base of the posterior parapods with dorsal lobe, bearing 4 setae ( Fig. 21 ): 1 thin seta 33–50 long; 1 bifid-trifid seta 63–80 long; 1 thick seta 20–33 long; 1 longer seta 95–107 long. Two rings of claws on posterior parapods: the longer claws forming an apical ring, the shorter forming a subapical ring.

Figures

FIGURES 2 – 6. Podonomus tehuelche sp. n. Male: 2, head; 3, antenna, 4, wing; 5, hypopygium, dorsal view, draw and photograph; 6, gonostylus. Scale bars = 100 μm, except for Fig. 6 = 20 μm.

FIGURES 7 – 9. Podonomus tehuelche sp. n. Female: 7, antenna; 8, wing; 9, genitalia: a—ventral view, draw and photograph, b—dorsal view, c—lateral view, draw and photograph. Scale bars = 100 μm.

FIGURES 10 – 15. Podonomus tehuelche sp. n. Pupa: 10, frontal apotome; 11, thoracic horn: a—draw and photograph, b—furrow of plastron plate with aeropyles (arrow indicating the aeropyles); 12, cephalothoracic setation; 13, entire abdomen, dorsal view; 14, abdominal setation of segment IV: dorsal (up), ventral (down); 15, segments VII – VIII and anal lobe. Scale bars: Figs 10, 11, 14, 15 = 100 μm; 12, 13 = 200 μm.

FIGURES 16 – 21. Podonomus tehuelche sp. n. Larva: 16, antenna; 17, labral setae; 18, mandible; 19, mentum; 20, procercus; 21, posterior parapods. Scale bars: Figs 16, 17, 19 = 20 μm; Figs 18, 20 = 50 μm; Fig. 21 = 100 μm.

Tables

TABLE 1. Lengths (μm) and proportions of male legs of Podonomus tehuelche sp. n. (n = 2); value of holotype in brackets.

fe	ti	ta1	ta2	ta3
p1 360–370 [370]	395–400 [395]	210–213 [210]	120–130 [120]	68–70 [70]
p2 445–450 [450]	390–400 [390]	180–188 [180]	110–113 [110]	63 [63]
p3 450–460 [460]	490–500 [500]	260–268 [260]	160–175 [160]	78–83 [78]