Labrundinia gregi 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 : 47-51

Labrundinia gregi Silva sp. n.

( Figs 20–22 )

Material examined. Type material: Holotype male with pupal and larval exuviae, Brazil: São Paulo, Ribeirão Preto, Monte Alegre Lake, 15.viii.1997, H. F. Mendes ( MZUSP).

Etymology. Named in honour of Greg Cowper, entomologist of the Academy of Natural Sciences of Philadelphia, for his friendship and encouragement.

Diagnostic characters. Labrundinia gregi sp. n. differs from other Labrundinia species by the combination of the following characters. Adult male: abdominal tergites II–VIII with continuous brown transverse band near proximal margin; hypopygium pale brown, sternapodeme with moderate anterior process; membranous anal point rounded, apical edge notched. Pupa: thoracic horn club-shaped, preapical indentation moderately deep, preapical papilla ratio 0.19; male genital sac extending somewhat beyond apex of anal lobe. Larva: head slender, head capsule surface covered with small spinules, lateroventral spine group present but weakly developed, with 3–4 spines, posteroventral spine group absent; subbasal seta of posterior parapod simple; bifid claw with V-shaped lower indentation.

Description. Adult male (n = 1)

Size. Total length 2.0 mm. Wing length 1.2 mm. Total length/wing length 1.68. Wing length/ profemur length 3.10.

Coloration. Head pale brown with dark brown occipital margin; pedicel and antenna brown; maxillary palp pale brown. Thorax brown with dark scutum; antepronotum pale brown; supraalar callus pale brown. Wing membrane transparent without any marking. Legs pale brown. Abdominal tergites II–VIII with continuous brown transverse band near proximal margin; hypopygium pale brown ( Fig. 20L ).

Head ( Figs 20A–E ). Temporal setae 10, uniserial ( Fig. 20B ). Eye ratio 1.17. Tentorium ( Fig. 20C ) 117 Μm long. Clypeus 76 Μm long, 46 Μm wide at largest part, bearing 15 setae. Cibarial pump 173 Μm long ( Fig. 20D ), with anterior margin concave. Lengths of palpomeres 1–5 (in Μm): 31; 50; 87; 118; 211. Antennal flagellum 689 Μm long, diameter of pedicel 96 Μm, apical setae single ( Fig. 20E ), AR 1.16.

Thorax. Antepronotum with 2 lateral setae. Acrostichals 26, biserial, diverging evenly posteriorly, starting close to antepronotum and almost reaching scutellum; dorsocentrals 16, irregularly uniserial; prealars 6; supraalars 2. Anapleural suture ratio 0.69. Scutellum with transverse row of 5 setae and group of numerous fine anterior setae.

Wing ( Fig. 20F ). Width 0.3 mm. Costa 1.0 mm long. R2+3 present. VR 0.74. WW 0.28. Brachiolum with 2 setae. Squama setiferous.

Legs ( Figs 20G–K ). Fore leg: width at apex of tibia 32 Μm ( Fig. 20G ), tibia with single, apical and pectinate spur 12 Μm long ( Fig. 20H ), with three lateral teeth and two preapical setae; ta1-4 without any preapical pseudospurs. Mid leg: width at apex of tibia 33 Μm long ( Fig. 20I ), tibia with single, apical and pectinate spur 14 Μm long with three lateral teeth ( Fig. 20J ) and two preapical setae; ta1-4 each with two preapical pseudospurs. Hind leg: width at apex of tibia 35 Μm long ( Fig. 20K ), tibia without spur; comb with 6 bristles; ta1-4 without any preapical pseudospurs. Claws slender, hooked; pulvilli absent. Lengths and proportion of leg segments as in Table 14.

fe ti ta1 ta2 ta3

p1 384 443 294 196 134 p2 526 454 583 247 130 p3 464 598 560 233 153

ta4 ta5 LR BV SV p1 101 65 0.66 2.26 2.81 p2 88 84 1.29 2.84 1.68 p3 106 72 0.94 2.87 1.90 Hypopygium ( Fig. 20M ). Tergite IX arched, with 10 posterior setae. Membranous anal point rounded, apical edge slightly notched. Phallapodeme 37 Μm long. Sternapodeme with moderate anterior process. Gonocoxite cylindrical, 89 Μm long, 33 Μm wide, with slightly concave inner margin. GcR 2.64. Gonostylus simple and slender, 60 Μm long; megaseta 10 Μm long. HR 1.50. HV 3.37.

Pupa (n = 1)

Size. Abdomen 1.6 mm long in male.

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

Cephalothorax ( Figs 21A–C ). Frontal apotome smooth ( Fig. 21A ). Wing sheath smooth 0.7 mm long. Thoracic horn 184 Μm long and 46 Μm wide ( Fig. 21B ), THR 3.96, preapical indentation moderately deep. Membranous preapical papilla 36 Μm long ( Fig. 21C ), PTH 0.19, aeropyle tube simple, short, 17 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 13 conical tubercles ( Fig. 21B ).

Abdomen ( Figs 21D–E ). Tergite I with scar 118 Μm long. T I–VI without shagreen, T VII–VIII with shagreen basally concentrated. Abdominal chaetotaxy as in figure 21D. Abdominal segment VII with 4 LS-setae. A VIII with 5 LS-setae. Anal lobe 269 Μm long and 133 Μm wide ( Fig. 21E ), outer margins sclerotized, with 9 spines, longest spine 12 Μm long, inner margins of lobes membranous. ALR 2.00. Male genital sac extending somewhat beyond apex of anal lobe.

4th instar larva (n = 1)

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. 22A ). Length 489 Μm, 249 Μm wide. IC 0.51. Surface covered with small spinules; lateroventral spine group present but weakly developed, with 3–4 spines; posteroventral spine group absent. Ventral cephalic setae S9, S10 and SSm forming a straight line diagonal to longitudinal axis of head capsule ( Fig. 22A ).

Antenna ( Figs 22B–C ). Length 262 Μm, A1 172 Μm long, with ring organ located 0.77 from base, A2 75 Μm long. AR 1.91. Blade longer than A2 over-reached by accessory blade.

Maxilla ( Fig. 22D ). Basal palp segment 20 Μm long and 8 Μm wide at the middle, with ring organ located 0.45 from base. PR 2.50. APR 8.60.

Mandible ( Fig. 22E ). Length 63 Μm. Sensillum campaniformium located 0.71 from apex, basal tooth bifid, with seta subdentalis projecting from sloping end towards apical tooth, accessory tooth present, AMD 2.73.

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

Hypopharyngeal complex ( Figs 22F–G ). Ligula 46 Μm long, 21 Μm wide, with row of 5 teeth. IO 0.99, MO 1.02. Paraligula bifid, 23 Μm long, inner tooth 18 Μm long, shorter than outer tooth. Pecten hypopharyngis with 8 teeth almost equal in size.

Body ( Figs 22H–I ). Without lateral fringe. Anterior parapods with simple claws. Procercus 112 Μm long, 25 Μm wide, with 7 anal setae 300 Μm long. L/ W 4.44. Supraanal seta well developed. Anal tubules not measurable. Posterior parapod 331 Μm long; subbasal seta on posterior parapod simple, without teeth ( Fig. 22H ); parapod apex with numerous simple claws; bifid claw with V-shaped lower indentation ( Fig. 22I ). B/C 1.10.

Adult female. Unknown.

Remarks. Adult males of Labrundinia gregi are very similar to those of L. parafittkaui , but can be separate by the notched apical edge of the anal point, which contrasts the convex apical edge present in L. parafittkaui . The pupae and larvae of L. gregi appear most similar to those of L. fittkaui and were fully discussed on the remarks of the latter. Labrundinia gregi has been recorded only from its type locality in São Paulo. The only larvae was collect in the Monte Alegre lake, a shallow system (2.90 m depth), with almost pH-neutral water (pH 6.8), medium level of dissolved oxygen (6.5 mg.L-1), low electrical conductivity (64 ΜScm-1) and temperature ranging from 22-28ºC.

Figures

FIGURES 20 A – M. Labrundinia gregi 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 21 A – E. Labrundinia gregi 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 22 A – I. Labrundinia gregi 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.