Polypedilum

Saether, Ole A., Andersen, Trond, Pinho, Luiz C. & Mendes, Humberto F., 2010, The problems with Polypedilum Kieffer (Diptera: Chironomidae), with the description of Probolum subgen. n., Zootaxa 2497, pp. 1-36 : 15-17

Polypedilum subgenus Probolum Andersen et Saether subgen. n.

Type species

Polypedilum (Probolum) marcondesi Pinho et Mendes sp. n.

Other included species

Polypedilum (Probolum) excelsius Townes sensu Grodhaus et Rotramel

Polypedilum pedatum excelsius Townes sensu Grodhaus et Rotramel, 1980: 70 . Polypedilum (Probolum) simantokeleum Sasa, Suzuki et Sakai

Polypedilum (Uresipedilum) simantokeleum Sasa, Suzuki et Sakai, 1998: 59 .

Polypedilum (Uresipedilum) simantokeleum Sasa, Suzuki et Sakai ; Saether and Oyewo (2008: 4). Polypedilum (Probolum) bullum Zhang et Wang

Polypedilum (Uresipedilum) bullum Zhang et Wang, 2004: 7 .

Polypedilum (Uresipedilum) bullum Zhang et Wang ; Saether and Oyewo (2008: 3). probably Polypedilum longinervis (Kieffer)

Microtendipes longinervis Kieffer, 1922: 10 .

Polypedilum (Polypedilum) longinervis (Kieffer) ; Freeman (1958: 290). possibly Polypedilum (Uresipedilum) excelsius Townes stat. n.

Polypedilum pedatum excelsius Townes, 1945: 55 .

Polypedilum (Uresipedilum) pedatum excelsius Townes ; Saether and Oyewo (2008: 3).

Etymology. From Greek probolos, any projecting or jutting object or prominence, referring to the inner basal projection of the superior volsella. Also Afro-American slang for a problem.

Diagnostic characters. The male imagines of the subgenus differ from the males of other subgenera primarily by having the base of the superior volsella much longer than wide with the apicomedian projection directed inwards, i.e. as in Uresipedilum , but with an additional inner lobe carrying 1–6 (10?) setae (or perhaps sometimes without the inner lobe).

The pupa has thoracic horn with 3–9 branches; lacks well developed frontal warts, but has relatively well developed cephalic tubercles with short frontal setae; often prealar tubercle; well developed pedes spurii A and B; transverse band of shagreen anteriorly on tergites II–V; conjunctives III/IV–V/VI with spinules; segment VIII with 4–5 taeniae and anal lobe without dorsal setae.

The larva has third antennal segment distinctly to slightly shorter than fourth; antennal blade slightly shorter than flagellum; accessory blade less than half as long; premandible bifid, with prominent premandibular brush; mentum with median teeth only slightly higher than first lateral pair and ventromental plates without posterior lobes and with median apices pointing towards each other.

Imago. Moderately sized species, wing length about 1.1–2.7 mm (or to 3.0 mm if P. longinervis is included). Thorax entirely pale or brown with darker markings. Abdomen entirely pale or broadly banded. Legs pale, femora and tibia with or without rings. Wing membrane with or without markings.

Antenna. AR higher than 1 (1.1–1.8 or 2.8 if P. longinervis is included).

Head. Eyes bare, frontal tubercles absent. Third palpomere bearing 3–4 lanceolate sensilla clavata. Temporals consisting of inner and outer verticals and few postorbitals.

Thorax. Antepronotum reduced, widely separated, without setae. Scutal tubercle present or possibly absent. Acrostichals long, dorsocentrals uniserial, supraalars absent. Scutellars uniserial.

Wing. Membrane bare, clear or with several darker spots. Brachiolum with 1 seta, R, R1 and R4+5 each with several setae, other veins bare. Squama with few to several (3–15) setae.

Legs. Fore tibial scale rounded, with or possibly sometimes without apical spur. Mid and hind tibiae with broad, unspurred anterior comb separated from posterior (narrower) comb with elongate spur. Sensilla chaetica absent.

Hypopygium. Anal tergite band well developed, fused basal to median anal tergite setae, several long median anal tergal setae, weaker apical anal tergite setae present lateral to anal point. Anal point narrow, parallel-sided, sometimes slightly spatulate. Superior volsella much longer than wide with apicomedian projection directed inwards, i.e. as in Uresipedilum , but with an additional inner microtrichiose lobe carrying 1–6 (10?) setae; base covered by microtrichia or with median part bare, with long outer seta; projection bare without setae or microtrichia. Inferior volsella slightly broadened subapically or more or less distinctly apically divided, with several sometimes apically split setae, long apical seta arising from tubercle.

Pupa. Small to medium sized, 4–7 mm long. Exuviae pale, marked with brown on margins of cephalothorax and abdomen, anal spur brown.

Cephalothorax. Frontal apotome smooth. Cephalic tubercles comparatively well-developed, frontal tubercles absent, frontal setae short. Prealar tubercle present or absent. Antepronotum with 1 median and 2 lateral antepronotals. Thoracic horn with 3(?)–9 branches. All thoracic setae short. Anterior dorsocentral (Dc1) close together with Dc2, Dc3 and Dc4 also close together.

Abdomen. Tergite I and IX without spines and shagreen; T II with broad anterior band of spinules, sometimes divided medially, otherwise with or without shagreen; T III–VI with broad anterior band of strong spinules, central line of sparse and weak to more numerous spinules which may be absent on T III, and posterior band of spinules. T VII and sometimes T VIII with bands of weak anterior spinules, otherwise bare. Sternites VI–VIII with or without weak anterior spinules. Tergite II with caudal hooklets arranged in single row. Spinules on conjunctives III/IV and IV/V in several rows, on conjunctive V/VI medially interrupted and in fewer rows. Pedes spurii A present on segment IV. Pedes spurii B well developed anterior on segment I and posterior on segment II.

Segments II–IV with 3 hair-like L setae; V and VI with 3, VII with 4, VIII with 4–5 taeniae; occasionally the number of taeniae reduced in some specimens. Anal spur single with lateral and basal denticles. Anal lobe well developed with complete fringe of about 20–60 long taeniae, dorsal taenia absent.

Larva. Medium sized larvae. Head capsule yellowish brown with mentum and apex of mandible dark brown and postoccipital margin black.

Antenna. Five segmented, third segment distinctly to slightly shorter than fourth; antennal ratio about 1.0 or slightly higher. Basal antennal segment with ring organ near base, blade slightly shorter than flagellum, accessory blade less than half as long. Style well developed, Lauterborn organs vestigial.

Dorsal surface of head. Frontoclypeal apotome anteriorly broadened into lateral rounded lobes on which S3 is situated, anterior margin straight.

Labro-epipharyngeal area. S I broad, apically plumose; S II very finely plumose on both sides. Labral lamella well developed, with about 50 teeth. Labrum with 2–3 weak spinulae and 4–5 weak chaetae. Pecten epipharyngis distinctly divided into 3 platelets, median with 3–5 teeth, lateral plates with 5–6 teeth. About 6– 7 curved, simple, pointed chaetulae laterales. Premandible bifid, with prominent premandibular brush.

Mandible. With 1 dorsal, 1 apical and 2 inner teeth. Seta subdentalis well developed, long. Seta interna consisting of 4 main branches with secondary numerous branches. Pecten mandibularis of about 6 setae.

Mentum. Median teeth and second laterals subequal in height, both slightly longer than first laterals. Ventromental plates without posterolateral lobes, median apices pointing towards each other.

Abdomen. Body setae inconspicuous. Anal lobe more or less well developed. Claws of posterior parapods all simple. Procercus short, bearing about 9 medium to long anal setae. Supraanal seta well developed, slightly less than half as long as anal setae. Anal tubules short, subequal.

Remarks. The pupae of Probolum are not separable from those of Polypedilum s. str., Pentapedilum and Uresipedilum . The known larvae may be separable by the combination of having mentum with median teeth only slightly higher than first lateral pair, ventromental plates without posterior lobes and mandible with dorsal tooth.