Labrundinia robacki Silva

Silva, Fabio Laurindo Da, Fonseca-Gessner, Alaide Aparecida & Ekrem, Torbjørn, 2014, A taxonomic revision of genus Labrundinia Fittkau, 1962 (Diptera: Chironomidae: Tanypodinae), Zootaxa 3769 (1), pp. 1-185 : 139-144

Labrundinia robacki Silva sp. n.

( Figs 67–69 )

Material examined. Type material: Holotype male with pupal and larval exuviae, Brazil: São Paulo, Ribeirão Preto, Monte Alegre Lake, 23.viii.1997, H. F. Mendes ( MZUSP). 12 Paratypes: 3 males with pupal exuviae same data as holotype ( NTNU); 1 female with pupal exuviae same data as holotype ( NTNU); 2 males same data as holotype ( NTNU); 1 male with pupal exuviae same data as holotype except for 26.ii.1997 ( NTNU); 2 pupa same data as holotype ( NTNU); 2 males same data as holotype except for 30.viii.1997 ( NTNU); 1 male same data as holotype except for Mato Grosso, Nova Mutum, Fazenda Buriti, Buriti stream, 09.i.1999 ( NTNU).

Etymology. Named in honour of Selwyn S. Roback, for his contribution to the knowledge of Chironomidae .

Diagnostic characters. Labrundinia robacki sp.n. differs from other Labrundinia species by the combination of the following characters. Adult male: fore leg with tibial comb; abdominal tergites I–II, VIII pale, T II–IV, VI– VII with continuous brown transverse band near proximal margin, T V with divided brown transverse band near proximal margin; hypopygium pale, sternapodeme with moderate anterior process. Pupa: thoracic horn light bulbshaped with lateromedial papilla, preapical indentation absent; genital sac elongated, not reaching apex of anal lobe. Larva: surface of head capsule covered with small spinules or nodules, with ventral maculation; lateroventral spine group present with one single, well-developed spine; posteroventral spine group present with about 18 spines; bifid claw of posterior parapod with U-shaped lower indentation.

Description. Adult male (n = 10)

Size. Total length 1.8–2.5 mm. Wing length 1.1–1.3 (9) mm. Total length/wing length 1.57–1.94. Wing length/ profemur length 2.01–3.05.

Coloration. Head yellow-brown with dark brown occipital margin; pedicel and antenna brown; maxillary palp pale brown. Thorax pale brown with dark scutum; antepronotum yellow-brown; supraalar callus brown. Wing membrane transparent without any marking. Legs pale brown. Tibia I-III with apex brown. Abdominal tergites I– II, VIII pale, T II–IV, VI–VII with continuous brown transverse band near proximal margin, T V with divided brown transverse band near proximal margin; hypopygium pale ( Fig. 67L ).

Head ( Figs 67A–E ). Temporal setae 10–14, uniserial ( Fig. 67B ). Eye ratio 1.00–1.39 (7). Tentorium ( Fig. 67C ) 125–146 (6) Μm long. Clypeus 91–106 Μm long, 58–67 Μm wide at largest part, bearing 16–20 setae. Cibarial pump 160–201 Μm long ( Fig. 67D ), with anterior margin concave. Lengths of palpomeres 1–5 (in Μm): 29–35; 34–49; 109–134; 111–142 (8); 197–208 (8). Antennal flagellum 680–790 (9) Μm long, diameter of pedicel 92–120 (8) Μm, apical setae single ( Fig. 67E ), AR 1.18–1.34 (9).

Thorax. Antepronotum with 2–4 (7) lateral setae. Acrostichals 34–40 (5), biserial, diverging evenly posteriorly, starting close to antepronotum and almost reaching scutellum; dorsocentrals 20–30 (7), irregularly biserial; prealars 7–9; supraalars 2 (9). Anapleural suture ratio 0.35–0.52. Scutellum with transverse row of 8–10 (6) setae and group of numerous fine anterior setae.

Wing ( Fig. 67F ). Width 0.3–0.4 mm. Costa 1.0– 1.2 mm long. R2+3 present. VR 0.71–0.78. WW 0.27–0.29. Brachiolum with 2 setae. Squama setiferous.

Legs ( Figs 67G–K ). Fore leg: width at apex of tibia 38–43 Μm ( Fig. 67G ), tibia with single, apical and pectinate spur 15–21 Μm long ( Fig. 67H ), with three lateral teeth and two preapical setae; comb with 6 bristles; ta1- 4 without any preapical pseudospurs. Mid leg: width at apex of tibia 38–44 Μm long ( Fig. 67I ), tibia with single, apical and pectinate spur 20–23 (8) Μm long with three lateral teeth ( Fig. 67J ) and two preapical setae; ta1-4 each with two preapical pseudospurs. Hind leg: width at apex of tibia 38–44 Μm long ( Fig. 67K ), tibia without spur; comb 6 setae; ta1-4 with two preapical pseudospurs. Claws slender, hooked; pulvilli absent. Lengths and proportion of leg segments as in Table 45.

Hypopygium ( Fig. 67M ). Tergite IX arched, with 10–15 (9) posterior setae. Membranous anal point rounded, apical edge slightly notched. Phallapodeme 51–69 (9) Μm long. Sternapodeme with moderate anterior process. Gonocoxite cylindrical, 110–137 (7) Μm long, 43–52 (7) Μm wide, with slightly concave inner margin. GcR 2.27– 2.51 (7). Gonostylus simple and slender, 75–100 Μm long; megaseta 12–18 Μm long. HR 1.37–1.50 (7). HV 2.40– 2.77 (7).

Adult female (n = 1)

Size. Total length 1.9 mm. Wing length 0.9 mm. Total length/wing length 2.24. Wing length/ profemur length 2.66.

fe ti ta1 ta2 ta3

p1 406–487 400–525 218–344 200–250 125–163 p2 581–675 381–487 575–618 231–275 118–175 p3 481–563 519–593 488–613 200–263 131–181

ta4 ta5 LR BV SV

p1 94–144 63–81 0.55–0.66 2.04–2.24 2.69–3.19 p2 106–118 63–88 1.22–1.31 2.61–2.85 1.73–1.89 p3 88–118 63–93 0.92–1.05 2.59–2.94 1.81–2.15 Coloration. Head yellow-brown with dark brown occipital margin; pedicel and antenna brown; maxillary palp pale brown. Thorax brown with dark scutum; antepronotum yellow-brown. Wing membrane transparent without any marking. Legs pale brown. Abdomen pale brown, with dark brown transverse bands near proximal margin, not much distinguishable. Seminal capsules brown.

Head. Temporal setae not observed. Eyes ratio not measurable. Tentorium 146 Μm long. Clypeus 98 Μm long, 76 Μm wide at largest part, bearing 21 setae. Cibarial pump 161 Μm long, as in male. Lengths of palpomeres 1–5 (in Μm): 27; 38; 91; 97; 139. Antenna flagellum 358 Μm long, diameter of pedicel 63 Μm, AR 0.37.

Thorax. Antepronotum with 1 seta. Acrostichals uncounted, irregularly uniserial, starting close to antepronotum; dorsocentrals 30, irregularly biserial; prealars 9; supraalars 2. Scutellum with transverse row of 8 setae and group of numerous fine anterior setae.

Wing. Width 0.3 mm. Costa 0.7 mm long. R2+3 present. VR 0.75. WW 0.37. Brachiolum with 2 setae. Squama setiferous.

Legs. Fore leg: width at apex of tibia 29 Μm, tibia with single, apical and pectinate spur 22 Μm, with three lateral teeth and two preapical setae; comb not observed; ta1-4 without any preapical pseudospurs. Mid leg: width at apex of tibia 37 Μm, tibia with single, apical and pectinate spur 20 Μm, with three lateral teeth and two preapical setae; ta1-4 each with two preapical pseudospurs. Hind leg: width at apex of tibia 36 Μm long, tibia without spur; comb with 6 bristles; ta1 with preapical two pseudospurs. Claws slender, hooked; pulvilli absent. Lengths and proportion of leg segments as in Table 46.

fe ti ta1 ta2 ta3

p1 285 316 225 133 84

p2 484 351 391 168 104 p3 416 419 386 163 141

ta4 ta5 LR BV SV p1 62 57 0.71 2.45 2.66 p2 94 66 1.12 2.82 2.13 p3 87 72 0.92 2.64 2.16 Genitalia. Gonapophysis VIII broadly rounded, 58 Μm long. Coxosternapodeme 79 Μm long. Postgenital plate rounded. Cerci oval-quadrate, 61 Μm long and 12 Μm wide; with 4 elongated setae. Labia with inconspicuous microtrichia. Notum length 78 Μm long. Seminal capsules oval, 41 Μm long, 26 Μm wide, with conical shaped necks. Length ratio SCa/No 0.53.

Pupa (n = 8 unless otherwise stated)

Size. Abdomen 1.7–2.1 (6) mm long in male, 2.0–2.1 (2) mm long in female.

Coloration. Exuviae mostly pale brown; thoracic horn and apex of anal lobe brown.

Cephalothorax ( Figs 68A–C ). Frontal apotome smooth ( Fig.68A ). Wing sheath smooth 0.7–0.8 mm long. Thoracic horn 263–325 (7) Μm long and 181–219 (7) Μm wide ( Fig. 68B ), THR 1.37–1.82 (7), preapical indentation absent. Membranous preapical papilla 32–66 (7) Μm long ( Fig. 68C ), PTH 0.12–0.24, aeropyle tube simple, short, 29–45 (5) Μm long; plastron plate small. Horn sac well developed, completely filling respiratory atrium. Reticulation of respiratory atrium indistinct, external membrane with pale spinules. Basal lobe wedgeshaped. Thoracic comb with 8–11 conical tubercles ( Fig. 68B ).

Abdomen ( Figs 68D–E ). Tergite I with scar 112–134 Μm long. T I without shagreen, T II–VI with a few spines medial basal concentrated, T VII–VIII with shagreen basally concentrated. Abdominal chaetotaxy as in figure 68D. Abdominal segment VII with 4 LS-setae. A VIII with 5 LS-setae. Anal lobe 293–363 Μm long and 163–194 Μm wide ( Fig. 68E ), outer margins sclerotized, with 10–12 spines, longest spine 11–15 Μm long, inner margins of lobes membranous. ALR 1.61–2.23. Male genital sac not reaching apex of anal lobe.

4th instar larva (n = 1 unless otherwise stated)

Coloration. Head pale yellow, with maculation as in figure 69A; postoccipital margin brown. Second antennal segment brown; distal tooth of mandible and apex of ligula brown. Abdomen pale yellow; procercus and anal setae pale brown. Posterior parapod claws all pale yellow.

Head ( Fig. 69A ). Length 570 Μm, 414 Μm wide. IC 0.72. Surface covered with small spinules or nodules; lateroventral spine group present with one single, well developed spine; posteroventral spine group present with about 18 spines. Ventral cephalic setae S9 and S10 and ventral pore (VP) forming a more or less right angle ( Fig. 69A ).

Antenna ( Figs 69B–C ). Length 274 Μm, A1 199 Μm long, with ring organ located 0.84 from base, A2 66 Μm long. AR 2.60. Blade longer than A2 over-reached by accessory blade.

Maxilla ( Fig. 69D ). Basal palp segment 32 Μm long and 8 Μm wide at the middle, with ring organ located 0.86 from base. PR 4.4. APR 6.12.

Mandible ( Fig. 69E ). Length 69 Μm. Sensillum campaniformium located 0.75 from apex, basal tooth bifid, with seta subdentalis projecting from sloping end towards apical tooth, accessory tooth present, AMD 2.89.

Mentum and M appendage . Dorsomental teeth reduced; pseudoradula uniformly granulate, 48 Μm long.

Hypopharyngeal complex ( Figs 69F–G ). Ligula 56 Μm long, 26 Μm wide, with row of 5 teeth. IO 0.94, MO 0.96. Paraligula bifid, 23 Μm long, inner tooth 21 Μm long, shorter than outer tooth. Pecten hypopharyngis with 6 teeth almost equal in size.

Body ( Figs 69H–I ). Without lateral fringe. Anterior parapods with simple claws. Procercus 98 Μm long, 29 Μm wide, with 7 anal setae, 489 Μm long. L/ W 3.34. Supraanal seta well developed. Anal tubules

not observed. Posterior parapod 458 Μm long; subbasal seta on posterior parapod simple, without spines ( Fig. 69H ); parapod apex with numerous simple claws; bifid claw with U-shaped lower indentation ( Fig. 69I ). B/C 0.84.

Remarks. Adult males of Labrundinia robacki are very similar to those of L. trilucida , but can be distinguished by the faint transverse band on abdominal tergite V, the pale tergite VIII, and the presence of a tibial comb on the fore leg, which contrast the completely brown abdominal tergite V, the almost brown tergite VIII, and the absence of a fore tibial comb in L. trilucida . The distinctive thoracic horn with lateromedial papilla distinguishes the pupae of L. robacki from any known Labrundinia species. The surface of the head capsule covered with nodules combined with the single, enlarged spur in the lateroventral spine group distinguish the larvae of L. robacki from all other Labrundinia species. Jacobsen (2008) illustrated and keyed the pupa of an undescribed species from Florida ( USA), which appears to be similar to L. robacki . The larva of this specimen was ascribed to the larval type called L. sp. B ( Epler 2001), which also seems to match with L. robacki except for having a bifid claw with V-shaped lower indentation in the posterior parapod. Although these specimens may represent one species, we hesitate to ascribe L. robacki to L. sp. B as the adult male of the latter remains unknown. Labrundinia robacki has been collected in the Monte Alegre lake (São Paulo State), a shallow system (2.90 m depth), with close to neutral water (pH 6.8), medium level of dissolved oxygen (6.5 mg.L-1), low electrical conductivity (64 ΜS.cm-1) and temperature ranging from 22–28ºC. This species has been also recorded from Mato Grosso State, Brazil.

Figures

FIGURES 67 A – M. Labrundinia robacki Silva sp. n., adult male. A. Head, frontal view. B. Temporal setae. C. Tentorium. D. Cibarial pump. E. Apex of antenna. F. Wing. G. Apex of fore tibia. H. Fore tibial spur. I. Apex of mid tibia. J. Mid tibial spur. K. Apex of hind tibia with comb. L. Abdominal coloration pattern, dorsal aspect. M. Hypopygium, left: ventral aspect, right: dorsal aspect.

FIGURES 68 A – E. Labrundinia robacki Silva sp. n., pupa. A. Frontal apotome. B. Thoracic horn with basal lobe and thoracic comb. C. Apex of thoracic horn showing preapical papilla. D. Abdominal segments with chaetotaxy, dorsal aspect. E. Anal lobe and male genital sac, ventral aspect.

FIGURES 69 A – I. Labrundinia robacki Silva sp. n., larva. A. Head with chaetotaxy and detail of lateroventral spine group, left: ventral aspect, right: dorsal aspect. B. Antenna. C. Apex of antenna. D. Maxillary palp. E. Mandible. F. Ligula and paraligula. G. Pecten hypopharyngis. H. Subbasal seta of posterior parapod. I. Bifid claw of posterior parapod.