Labrundinia becki Roback, 1971

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 : 18-24

Labrundinia becki Roback, 1971

( Figs 5–7 )

Labrundinia pilosella Beck and Beck (nec. Loew), 1966: 340 (description of adults and immatures).

Labrundinia becki Roback, 1971: 279 (description of male); Roback 1987: 184 (description of immatures).

Material examined. Type material: Holotype male, USA: Florida, Tucker, 15.iv.1952, J. R. Vockeroth ( CNC). Additional material: 1 male with pupal exuviae, USA: Florida, Flagler County, Rayonier Forest, 27.x.1967. W. Beck; 1 larva as previous except for Leon, Polk Creek, 10 mi SW Tallahassee, 9.vi.1972; 1 pupa with larval exuviae as previous except for Little Haw Creek, 8.vi.1964. 1 male, Georgia, Clarke, Sways Area (near Oconee River) 24.vii.1978; 1 female with pupal and larval exuviae as previous except for Laurens County, 13.iii.1986; 1 female with pupal exuviae as previous. 1 male with pupal exuviae. 1 male with pupal exuviae, Pennsylvania, Wayne County, Lake Lacawac, 19.ix.1970. S.S. Roback; 1 female as previous. 1 male, South Carolina, Tinken Creek, Savannah River Plant, 19–20.ix.1980, P.L. Hudson; 3 larvae as previous except Horry, 1.vii.1979, T.R. White; 1 larva as previous except for Anderson, Charles Creek, 21.ix.1975, P.H. Carlson.

Diagnostic characters. Labrundinia becki differs from other Labrundinia species by the combination of the following characters. Adult male: R2+3 present; abdomen completely brown; hypopygium brown, sternapodeme with reduced anterior process. Pupa: thoracic horn semi-globose with preapical indentation shallow; male genital sac extending somewhat beyond apex of anal lobe. Larva: Surface of head capsule smooth, lateroventral spine group with several small spines; posterior parapod with subbasal seta simple and bifid claw with V-shaped lower indentation.

Description. Adult male (n = 5 unless otherwise stated)

Size. Total length 1.9–2.6 (4) mm. Wing length 1.2–1.6 (3) mm. Total length/wing length 1.65–1.99 (4). Wing length/ profemur length 2.24–2.79 (3).

Coloration. Head brown with dark brown occipital margin; pedicel and antenna brown; maxillary palp pale brown. Thorax brown with dark scutum; antepronotum pale. Wing membrane transparent without any marking. Legs pale brown. Abdomen including hypopygium completely brown ( Fig. 5L ).

Head ( Figs 5A–E ). Temporal setae 14 (3), uniserial ( Fig. 5B ). Eye ratio 0.37–0.53 (2). Tentorium ( Fig. 5C ) 124–141(3) Μm long. Clypeus 98–120 (3) Μm long, 80–82 (3) Μm wide at largest part, bearing 14 (3) setae. Cibarial pump 153–182 (2) Μm long ( Fig. 5D ), with anterior margin concave. Lengths of palpomeres 1–3 (in Μm): 31 (1); 51(1); 98 (1). Antennal flagellum 639–676 (2) Μm long, diameter of pedicel 98–120 (2) Μm, apical setae single ( Fig. 5E ), AR 1.06–1.07 (2).

Thorax. Antepronotum with 3 (2) lateral setae. Acrostichals 36–42 (2), biserial, diverging evenly posteriorly, starting close to antepronotum and almost reaching scutellum; dorsocentrals 16–26 (2), irregularly uniserial; prealars 7–9 (2); supraalars 2 (2). Anapleural suture ratio 0.41–0.49 (2). Scutellum with transverse row of 9–10 setae and group of numerous fine anterior setae.

Wing ( Fig. 5F ). Width 0.3–0.4 (3) mm. Costa 1.5–1.2 (2) mm long. R2+3 present. VR 0.70–0.74 (2). WW 0.28– 0.29 (3). Brachiolum with 2 setae (2). Squama setiferous.

Legs ( Figs 5G–K ). Fore leg: width at apex of tibia 31–39 Μm ( Fig. 5G ), tibia with single, apical and pectinate spur 11–16 (2) Μm long ( Fig. 5H ), with three lateral teeth and two preapical setae; ta1-4 without any preapical pseudospurs. Mid leg: width at apex of tibia 39, 39 (3) Μm long ( Fig. 5I ), tibia with single, apical and pectinate spur 24 (1) Μm long with three lateral teeth ( Fig. 5J ) and two preapical setae; ta1-4 each with one preapical pseudospurs. Hind leg: width at apex of tibia 39 (2) Μm long ( Fig. 5K ), tibia without spur; comb with 5 (3) bristles; ta1-4 without any preapical pseudospurs. Claws slender, hooked; pulvilli absent. Lengths and proportion of leg segments as in Table 5.

fe ti ta1 ta2 ta3

p1 429–546 (3) 500–531 (3) 234 (1) 109 (1) 86 (1) p2 547–626 (3) 515–547 (2) 625 (1) 265 (1) 156 (1) p3 477–555 (3) 656–727 (3) 672 (1) 289 (1) 195 (1)

ta4 ta5 LR BV SV

p1 55 (1) 39 (1) 0.55 (1) 4.16 (1) 3.40 (1) p2 102 (1) 78 (1) 1.14 (1) 2.98 (1) 1.88 (1) p3 117 (1) 78 (1) 0.92 (1) 2.87 (1) 1.90 (1) Hypopygium ( Fig. 5M ). Tergite IX arched, with 11 (4) posterior setae. Membranous anal point trapezoidal. Phallapodeme 45–55 Μm long. Sternapodeme with reduced anterior process. Gonocoxite cylindrical, 90–113 Μm long, 47–59 Μm wide, with slightly concave inner margin. GcR 1.76–2.25 (4). Gonostylus simple and slender, 55– 64 Μm long; megaseta enlarged, 10–14 (4) Μm long. HR 1.58–1.85. HV 3.04–3.35 (3).

Adult female (n = 2 unless otherwise stated)

Size. Total length 1.5 mm. Wing length 1.1 mm. Total length/wing length 1.25–1.37. Wing length/ profemur length 2.50–2.76.

Coloration. Head, pedicel and antenna brown; maxillary palp pale brown. Thorax pale brown with dark scutum; supraalar callus brown. Wing membrane transparent without any marking. Legs brown to pale brown. Abdomen completely brown. Seminal capsules brown.

Head. Temporal setae 11–16, uniserial. Eyes ratio 0.78 (1). Tentorium 134 (1) Μm long. Clypeus 81 (1) Μm long, 74 (1) Μm wide at largest part, bearing 21–26 setae. Cibarial pump 143–185 Μm long, as in male. Lengths of palpomeres 1–5 (in Μm): 22–40; 47–52; 75–85; 118–130; 167–209. Antennal flagellum 407 (1) Μm long, diameter of pedicel 60–75 Μm, AR 0.42 (1).

Thorax. Antepronotum with 1 lateral seta. Acrostichals 32–34, irregularly biserial, starting close to antepronotum; dorsocentrals 32, irregularly uniserial; prealars 10–12; supraalars 2. Scutellum with transverse row of 10 setae and group of numerous fine anterior setae.

Wing. Width 0.4 mm. Costa 1.0 (1) mm long. R2+3 present. VR 0.68 (1). WW 0.34–0.36. Brachiolum with 2 setae (2). Squama setiferous.

Legs. Fore leg: width at apex of tibia 39–44 Μm, tibia with single, apical and pectinate spur 12–17 Μm long, with three lateral teeth and two preapical setae; preapical pseudospurs on ta1-4 not observed. Mid leg: width at apex of tibia 32–46 Μm, tibia with single, apical and pectinate spur 16–19 Μm long, with three lateral teeth and two preapical setae; preapical pseudospurs on ta1-4 not observed. Hind leg: width at apex of tibia 40–46 Μm, tibia without spur; comb with 7 bristles; preapical pseudospurs on ta1-4 not observed. Claws slender, hooked; pulvilli absent. Lengths and proportion of leg segments as in Table 6.

fe ti ta1 ta2 ta3

p1 401–421 367–375 195 (1) 156 (1) 102 (1) p2 485–561 438–493 445 (1) 195 (1) 140 (1) p3 468–503 515–617 – – –

ta4 ta5 LR BV SV

p1 78 (1) 62 (1) 0.53 (1) 2.47 (1) 4.04 (1) p2 94 (1) 78 (1) 1.02 (1) 2.69 (1) 2.07 (1) p3 – – – – – Genitalia. Gonapophysis VIII broadly rounded, 75 (1) Μm long. Coxosternapodeme 85 (1) Μm long. Tergite X with 10 lateroventral setae on each side. Postgenital plate rounded. Cerci squarish, 28 (1) Μm long and 26 (1) Μm wide; with 4 (1) elongated setae. Labia with inconspicuous microtrichia. Notum length 104 (1) Μm long. Seminal capsules oval, 45 (1) Μm long, 30 (1) Μm wide, with conical shaped necks. Length ratio SCa/No 0 43 (1).

Pupa (n = 4 unless otherwise stated)

Size. Abdomen 1.6–1.9 (3) mm long in male, 2.3 (1) mm long in female.

Coloration. Exuviae and thoracic horn brown. Apex of anal lobe brown.

Cephalothorax ( Figs 6A–C ). Frontal apotome smooth ( Fig. 6A ). Wing sheath smooth 0.7–0.8 mm long. Thoracic horn 197–248 Μm long and 65–70 Μm wide ( Fig. 6B ), THR 2.66–2.88 (3), preapical indentation moderately deep. Membranous preapical papilla 14–22 Μm long ( Fig. 6C ), PTH 0.07–0.09, aeropyle tube simple, short and robust, 20–24 (2) Μm long; plastron plate small. Horn sac well developed, completely filling respiratory atrium. External membrane with pale spinules basally concentrated. Basal lobe wedge-shaped. Thoracic comb with 12 (3) conical tubercles ( Fig. 6B ).

Abdomen ( Figs 6D–E ). Tergite I with scar 88 (1) Μm long. T I–VI without shagreen, T VII–VIII with shagreen basally concentrated. Abdominal chaetotaxy as in figure 6D. Abdominal segment VII with 4 LS-setae. A VIII with 5 LS-setae. Anal lobe 213–273 (2) Μm long and 139–156 Μm wide ( Fig. 6E ), outer margins sclerotized, with 6–10 (3) spines, longest spine 11–14 (3) Μm long, inner margins of lobes membranous. ALR 1.53–1.75 (2). Male genital sac extending somewhat beyond apex of anal lobe.

4th instar larva (n = 6 unless otherwise stated)

Coloration. Head pale yellow, without maculation; postoccipital margin brown. Second antennal segment pale 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. 7A ). Length 453–504 (3) Μm, 257–305 (3) Μm wide. IC 0.58–0.60 (3). Surface smooth; lateroventral spine group present but weakly developed, with 3–4 spines; posteroventral spine group absent. Ventral cephalic setae S9, S10 and SSm forming a more or less straight line perpendicular to longitudinal axis of head capsule ( Fig. 7A ).

Antenna ( Figs 7B–C ). Length 253–282 Μm, A1 165–189 Μm long, with ring organ located 0.45–0.76 from base, A2 77–84 Μm long. AR 1.89–2.08. Blade and accessory blade not observed.

Maxilla ( Fig. 7D ). Basal palp segment 18–23 Μm long and 7–9 Μm wide at the middle, with ring organ 0.72– 0.83 (3) from base. PR 2.33–2.89. APR 8.10–8.64.

Mandible ( Fig. 7E ). Length 56–71 Μm. Sensillum campaniformium located 0.70–0.86 from apex, basal tooth bifid, with seta subdentalis projecting from sloping end towards apical tooth, accessory tooth present, AMD 2.59– 3.26.

Mentum and M appendage . Dorsomental teeth reduced; pseudoradula uniformly granulate.

Hypopharyngeal complex ( Figs 7F–G ). Ligula 47–58 Μm long, 23–28 Μm wide, with row of 5 teeth. IO 0.92– 0.99, MO 1.01–1.04. Paraligula bifid, 23–29 Μm long, inner tooth 18–23 Μm long, shorter than outer tooth. Pecten hypopharyngis with 6 teeth almost equal in size.

Body ( Figs 7H–I ). Without lateral fringe. Anterior parapods with simple claws. Procercus 129–166 Μm long, 25–36 Μm wide, with 7 anal setae 437–572 (4) Μm long. L/ W 3.98 –4.60. Supraanal seta well developed. Anal tubules 129–157 (2) Μm long. Posterior parapod 331–368 (4) Μm long; subbasal seta simple on posterior parapod, basal spines reduced, 1–3 spines ( Fig. 7H ); parapod apex with numerous simple claws; bifid claw with V-shaped lower indentation ( Fig. 7I ). B/C 1.02–1.05 (4).

Remarks. Labrundinia becki is very similar to L. parabecki in the adult males, but can be separated from this species by the uniformly coloured abdominal tergites II–IV in contrast to the darker cruciate mark present on the same abdominal tergites of L. parabecki . The pupae of L. becki are perhaps most similar to those of L. neopilosella , but can be separated by the position of the aeropyle tube lying along the outer margin of the thoracic horn. The larvae are apparently most similar to those of L. longipalpis and L. neopilosella , but can be separated from these species by having a simple subbasal seta on the posterior parapod, which differs from the serrated subbasal setae present in L. longipalpis and L. neopilosella . Labrundinia becki has so far been recorded from the east coast of the United States ( Roback 1987a) in creeks, small rivers and lakes.

Figures

FIGURES 5 A – M. Labrundinia becki Roback, 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 6 A – E. Labrundinia becki Roback, 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 7 A – I. Labrundinia becki Roback, 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.