Labrundinia pilosella ( Loew, 1866 )

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 : 127-132

Labrundinia pilosella ( Loew, 1866)

( Figs 61–63 )

Tanypus pilosellus Loew, 1866: 5 (description female).

Ablabesmyia pilosella ( Loew, 1866) : Johannsen 1905: 152 (description female, new combination).

Tanypus pilosellus ( Loew, 1866) : Malloch 1915: 372 (description of adults and immatures).

Pentaneura pilosella ( Loew, 1866) : Johannsen 1946: 293 (description of adults, new combination); Roback 1962: 253 (description of male and immatures); Sublette 1964: 100 (description of male).

Labrundinia floridana Beck and Beck, 1966: 339 (description of adults and immatures).

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

Labrundinia pilosella ( Loew, 1866) : Roback 1971: 276 (description of male); Roback 1987: 169 (description of immatures).

Material examined. Type material: Lectotype female, USA: District Columbia, O. Sacken ( MCZ 10370). 3 Paralectotypes: 3 females same data as lectotype.

Additional material: 1 male, Canada: Alberta, Bigoray river, 7.vi.1973, H. Boeger ( CNC CH 3104). 1 male with pupal and larval exuviae, Northwest Territory, Martin river, 5.vii.1973, B. Bilyj ( CNC CH 801.5). 1 male, Ontario, St. Lawrence Island. N. P (S.L.I.N.P.), Grenadier Island, 1.viii.1975, M. E. Roussel ( CNC CH 4076); 1 male as previous except for Gordon Island, 7.vii.1976 ( CNC CH 7010). 1 male as previous except for Mallorytown landing, 3.vi.1975 ( CNC CH 4055). 2 females (as previous except for Waterloo, Canagagigue river, 24.x.1975, B. Bilyj CNC CH 2795 and CH 2810). 1 female with pupal and larval exuviae, USA: Florida, Clay County, Peter's Creek, 7.iii.1963, W. Beck; 1 female with pupal and larval exuviae as previous except for 20.viii.1963. 1 male with pupal exuviae, Georgia, west of Preston, Kinchafoonee creek, 25.v.1972, S. S. Roback; 1 pupa as previous except for Girard, Savannah river, M 157, 6 mi, S. S. Roback; 1 larva as previous except for Crisp, Gum Creek, R+30, 6m. w of Corde, 31.x.1983, S. S. Roback. 1 larva, Illinois, Illiapolis, Ditch, Trib. Long pt., 25/ix.1984, S. S Roback. 1 male, Minnesota, Garrison Bay, Bay lake, 3.viii.1981, P. L. Hudson. 1 pupa, South Carolina, Allendale, Savannah river, station 5 M149, ca 6 mi w of Martin, 10.ix.1980, S. S. Roback; 1 larva as previous except for Colleton, Ashepoo river, close to Waterboro, 2.iv.1977, P. H. Carlson/T. R. White; 1 larva as previous except for Lexington, 28.xi.1976; 1 larva as previous except for station 4 at S.C Route 63 bridge, 21.vii.1964, S. S. Roback.

Diagnostic characters. Labrundinia pilosella differs from other Labrundinia species by the combination of the following characters. Adult male: abdominal tergite II pale brown, T III and V completely brown, T IV and VI with continuous brown transverse band near proximal margin, T VII–VIII completely brown; hypopygium pale brown, sternapodeme with distinct anterior process. Pupa: thoracic horn club-shaped; preapical indentation moderately deep, forming a distinct diverticulum; male genital sac extending much beyond apex of the anal lobe. Larva: surface of head capsule covered with spinules, posterior margin may be darkened, lateroventral and posteroventral spine groups absent; subbasal seta of posterior parapod simple; bifid claw with V-shaped lower indentation.

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

Size. Total length 2.7–3.2 (4) mm. Wing length 1.7–1.9 (4) mm. Total length/wing length 1.60–1.83 (4). Wing length/ profemur length 2.66–3.19.

Coloration. Head brown with dark brown occipital margin; pedicel and antenna brown; maxillary palp pale brown. Thorax brown with dark scutum; antepronotum pale brown. Wing membrane transparent without any marking. Legs pale brown. Abdominal tergite II pale brown, T III, V completely brown, T IV, VI with continuous brown transverse band near proximal margin, T VII–VIII completely brown; hypopygium pale brown ( Fig. 61L ).

Head ( Figs 61A–E ). Temporal setae 13–20, uniserial ( Fig. 61B ). Eye ratio 1.18–1.47. Tentorium ( Fig. 61C ) 165–178 Μm long. Clypeus 129–153 (4) Μm long, 94–112 (4) Μm wide at largest part, bearing 17–26 setae. Cibarial pump 196–216 Μm long ( Fig. 61D ), with anterior margin concave. Lengths of palpomeres 1–5 (in Μm): 35–39; 73– 88 (4); 153–171 (4); 157–176 (4); 280–310 (3). Antennal flagellum 686–931 Μm long, diameter of pedicel 120– 157 (4) Μm, apical setae single ( Fig. 61E ), AR 1.12–1.39 (4).

Thorax. Antepronotum with 6–9 lateral setae. Acrostichals 45–50 (4), biserial, diverging evenly posteriorly, starting close to antepronotum and almost reaching scutellum; dorsocentrals 22–34, irregularly multiserial; prealars 15–17; supraalars 3 (4). Anapleural suture ratio 0.41–0.59. Scutellum with transverse row of 10–12 setae and group of numerous fine anterior setae.

Wing ( Fig. 61F ). Width 0.4–0.5 (4) mm. Costa 1.4–1.6 (4) mm long. R2+3 present. VR 0.66–0.72 (4). WW 0.26–0.28 (4). Brachiolum with 2 setae. Squama setiferous.

Legs ( Figs 61G–K ). Fore leg: width at apex of tibia 47 (4) Μm ( Fig. 61G ), tibia with single, apical and pectinate spur 14–20 Μm long ( Fig. 61H ), with three lateral teeth and two preapical setae; ta1-4 without any preapical pseudospurs. Mid leg: width at apex of tibia 39–47 (4) Μm long ( Fig. 61I ), tibia with single, apical and pectinate spur 24–27 (4) Μm long with three lateral teeth ( Fig. 61J ) and two preapical setae; ta1-4 each with two preapical pseudospurs. Hind leg: width at apex of tibia 47–55 (3) Μm long ( Fig. 61K ), tibia without spur; comb with 5 (4) bristles; ta1-4 without any preapical pseudospurs. Claws slender, hooked; pulvilli absent. Lengths and proportion of leg segments as in Table 41.

fe ti ta1 ta2 ta3

p1 570–633 703–758 390–484 305–344 211–234 p2 742–828 766–805 664–758 352–383 188–203 p3 680–758 1008–1078 766–859 336–375 234–250

ta4 ta5 LR BV SV

p1 141–164 86–102 0.56–0.64 2.15–2.32 2.94–3.40 p2 117–133 86–102 0.92–0.97 2.65–2.90 2.08–2.20 p3 156–172 86–102 0.80–0.84 2.94–3.00 2.05–2.12 Hypopygium ( Fig. 61M ). Tergite IX arched, with 14 (3) posterior setae. Membranous anal point trapezoidal. Phallapodeme 61–82 (4) Μm long. Sternapodeme with distinct anterior process. Gonocoxite cylindrical, 145–169 (4) Μm long, 67–71 Μm wide, with slightly concave inner margin. GcR 2.38–2.42 (3). Gonostylus simple and slender, 84–100 Μm long; megaseta 14–18 (4) Μm long. HR 1.52–1.75. HV 2.87–3.20.

Adult female (n = 5 unless otherwise stated)

Size. Total length 1.6–1.9 (3) mm. Wing length 1.1–1.4 (4) mm. Total length/wing length 1.30–1.51 (3). Wing length/ profemur length 1.88–2.23 (4).

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

Head. Temporal setae 13–15, uniserial. Eyes ratio 1.03–1.12 (2). Tentorium 107 (1) Μm long. Clypeus 82 (1) Μm long, 66 (1) Μm wide at largest part, bearing 20–31 setae. Cibarial pump 186–215 Μm long, as in male. Lengths of palpomeres 1–5 (in Μm): 35–39 (4); 67–82 (4); 120–148 (3); 127–155 (4); 153–227 (4). Antennal flagellum 335 Μm long, diameter of pedicel 55–67 Μm, AR 0.36 (1).

Thorax. Antepronotum with 5–7 (2) lateral setae. Acrostichals 40–48, irregularly biserial, starting close to antepronotum; dorsocentrals 30–38, irregularly biserial; prealars 12–16 (4); supraalars 3. Scutellum with transverse row of 10–12 setae and group of numerous fine anterior setae.

Wing. Width 0.5–0.6 mm. Costa 0.8 (1) mm long. R2+3 present. VR 0.69 (1). WW 0.35–0.40 (4). Brachiolum with 2 setae. Squama setiferous.

Legs. Fore leg: width at apex of tibia 39–47 (4) Μm, tibia with single, apical and pectinate spur 14–21 Μm long, with three lateral teeth and two preapical setae; ta1-4 each with one preapical pseudospurs. Mid leg: width at apex of tibia 39–55 Μm, tibia with single, apical and pectinate spur 17–23 Μm long, with three lateral teeth and two preapical setae; preapical pseudospurs on ta1-4 not observed. Hind leg: width at apex of tibia 39–55 Μm, tibia without spur; comb with 5 (3) bristles; preapical pseudospurs on ta1-4 not observed. Claws slender, hooked; pulvilli absent. Lengths and proportion of leg segments as in Table 42.

Genitalia. Gonapophysis VIII broadly rounded, 58 (1) Μm long. Coxosternapodeme 66 (1) Μm long. Postgenital plate rounded. Cerci oval-quadrate, 43 (1) Μm long and 13 (1) Μm wide. Labia with inconspicuous microtrichia. Notum length 81 (1) Μm long. Seminal capsules oval, 35–47 Μm long, 29–36 (2) Μm wide, with conical shaped necks. Length ratio SCa/No 0.47 (1).

fe ti ta1 ta2 ta3

p1 414–531 438–509 328–373 195–234 151–156 p2 590–700 593–645 570–618 258–291 141–172 p3 547–594 781–812 445–664 (2) 211–3.36 (2) 156–2.19 (2)

ta4 ta5 LR BV SV

p1 109–118 63–86 0.66–0.75 2.25–2.42 2.60–2.78 p2 86–118 70–93 0.95–1.28 2.83–3.03 1.88–2.23 p3 101–141 (2) 70–86 (2) 0.78–0.82 (2) 2.65–2.75 (2) 2.12–2.33 (2) Pupa (n = 4 unless otherwise stated)

Size. Abdomen 1.9–2.3 (3) mm long in male, 1.8 (1) mm long in female.

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

Cephalothorax ( Figs 62A–C ). Frontal apotome smooth ( Fig. 62A ). Wing sheath smooth 0.7–0.8 mm long. Thoracic horn 195–242 Μm long and 63–78 Μm wide ( Fig. 62B ), THR 2.6–3.50, preapical indentation moderately deep. Membranous preapical papilla 14–39 Μm long ( Fig. 62C ), PTH 0.06–0.20, aeropyle tube simple, short, 14– 29 Μm long; plastron plate small. Horn sac well developed, completely filling respiratory atrium. Reticulation of respiratory atrium indistinct. Basal lobe wedge-shaped. Thoracic comb with 8–12 conical tubercles ( Fig. 62B ).

Abdomen ( Figs 62D–E ). Tergite I with scar 103 (1) Μm long. T I–VI without shagreen, T VII–VIII with shagreen basally concentrated. Abdominal chaetotaxy as in figure 62D. Abdominal segment VII with 4 LS-setae. A VIII with 5 LS-setae. Anal lobe 250–313 (3) Μm long and 141–164 (3) Μm wide ( Fig. 62E ), outer margins sclerotized, with 11 (3) spines, longest spine 10–18 Μm long, inner margins of lobes membranous. ALR 1.62–1.90 (3). Male genital sac extending much beyond apex of anal lobe.

4th instar larva (n = 5 unless otherwise stated)

Coloration. Head pale yellow, posterior margin may be darkened; 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. 63A ). Length 407 (1) Μm, 277 (1) Μm wide. IC 0.68–0.84. Surface covered with small spinules; lateroventral and posteroventral spine groups absent. Ventral cephalic setae S9, S10 and SSm forming a more or less straight line perpendicular to longitudinal axis of head capsule ( Fig. 63A ).

Antenna ( Figs 63B–C ). Length 212–271 (4) Μm, A1 142–190 (4) Μm long, with ring organ located 0.61–0.84 (2) from base, A2 59–73 (4) Μm long. AR 2.33–2.34 (2). Blade longer than A2 over-reached by accessory blade.

Maxilla ( Fig. 63D ). Basal palp segment 26–38 Μm long and 8–14 Μm wide at the middle, with ring organ located 0.55–0.78 from base. PR 1.84–3.70. APR 5.05–8.62.

Mandible ( Fig. 63E ). Length 71–85 Μm. Sensillum campaniformium located 0.65–0.78 from apex, basal tooth bifid, with seta subdentalis projecting from sloping end towards apical tooth, accessory tooth present, AMD 2.23– 3.39 (3).

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

Hypopharyngeal complex ( Figs 63F–G ). Ligula 52–68 Μm long, 23–31 Μm wide, with row of 5 teeth. IO 0.94– 0.97, MO 1.00–1.06. Paraligula bifid, 23–29 Μm long, inner tooth 20–21 Μm long, shorter than outer tooth. Pecten hypopharyngis with 7–8 teeth almost equal in size.

Body ( Figs 63H–I ). Without lateral fringe. Anterior parapods with simple claws. Procercus 103–127 Μm long, 26–41 Μm wide, with 7 anal setae 411–565 (4) Μm long. L/ W 2.74 –4.48. Supraanal seta well developed. Anal tubules 167–176 (3) Μm long. Posterior parapod 294–366 (2) Μm long; subbasal seta on posterior parapod on posterior parapod simple, with 3–5 small teeth ( Fig. 63H ); parapod apex with numerous simple claws; bifid claw with V-shaped lower indentation ( Fig. 63I ). B/C 1.09–1.22.

Remarks. Adult males of Labrundinia pilosella are very similar to those of L. semicurvata , but can be distinguished by the longer wing, the pale brown hypopygium and by having about 14 posterior setae on the abdominal tergite IX. The pupae of Labrundinia pilosella appear most similar to those of L. parafittkaui and differences are discussed under this species. The larvae of L. pilosella can be separated from those of the related species L. separata and L. sofiae by the ratio between the inner and the outer tooth length on bifid claw (B/C) of the posterior parapod. This ratio is 1.09–1.22 in L. pilosella while it is 0.89–0.97 in L. separata and L. sofiae . Roback (1971) placed L. pilosella as a senior synonym of L. floridana Beck and Beck due to the absence of distinguishable features in the adult males. Later, the comparison of the reared material of L. pilosella with that of L. floridana revealed consistent differences between the immatures. The larva described for L. floridana has a cephalic posterior margin noticeably darker than rest of head capsule, a character not observed in the material previously attributed to L. pilosella . We have examined material assigned to both species. Although there are slight differences that might indicate different species, we do not have enough data to warrant separation and treat L. floridana as a junior synonym of L. pilosella . Labrundinia pilosella is the most widespread Labrundinia species in North America. The larvae were collected in lakes, creeks, pools, rivers and streams.

Figures

FIGURES 61 A – M. Labrundinia pilosella (Loew), 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 62 A – E. Labrundinia pilosella (Loew), 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 63 A – I. Labrundinia pilosella (Loew), larva. A. Head with chaetotaxy, 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.