Ubatubaneura, Wiedenbrug, Sofia & Trivinho-Strixino, Susana, 2009

Wiedenbrug, Sofia & Trivinho-Strixino, Susana, 2009, Ubatubaneura, a new genus of the Corynoneura group (Diptera: Chironomidae: Orthocladiinae) from the Brazilian Atlantic Forest, Zootaxa 1993, pp. 41-52 : 44-46

Ubatubaneura n. gen.

Thienemanniella sensu Ospina-Torres (1992: 223) pro parte, nec Kieffer. Corynoneura Gruppe sensu Wiedenbrug (2000: 98) pro parte.

Type species. Ubatubaneura atlantica n. sp., by present designation.

Diagnosis. The male can be separated from other members of the Corynoneura group on the following combination of characters: head with right-angled dorsolateral region; eyes bare; terminal flagellomere of antenna with triangular apex surrounded by sensilla chaetica; antepronotal lobes not narrowed medially; hind tibia with two long spurs of which one is curved, tibial comb normal; hypopygium without anal point; transverse sternapodeme slightly concave without oral projections; phallapodeme with straight distal margin, not strongly curved posteriad.

The pupa can be separated from other members of the Corynoneura group by the following combination of characters: frontal setae long and strong, on small tubercles; four dorsocentrals in two pairs, Dc3 conspicuously longer and stronger than the others; pearl row present; conjunctives between tergites II/ III–TVI/VII with strong hooklets; segments III–V with two long taeniate L-setae each; segments VI–VIII with non taeniate L-setae only; with three anal macrosetae on small tubercles located ventrally on anal lobe; distal 1/3 of anal lobe with fringe of long taeniate setae.

The larva can be separated from other members of the Corynoneura group by the following combination of characters: antenna 5-segmented, about 1/2 the length of the head; antennal blade not longer than flagellum; SI bifid; body setae short; sub-basal seta on posterior parapod split apically.

Etymology. Named after the district of Ubatuba in São Paulo State, where most of the specimens were collected. Gender: feminine.

Description. Male. Small species, wing length about 0.5 mm.

Head. Dorsolateral region of head right-angled. Eye bare, without dorsomedial extension. Outer verticals and postorbitals few. Tentorium long, narrow, tapering towards apex. Cibarial pump comparatively broad. Clypeus narrow, with setae in single row. Antenna with 10 flagellomeres and well developed plume; AR about 0.3; groove beginning on flagellomere 2; terminal flagellomere with distal sensilla chaetica in single, interrupted row surrounding triangular apex; with two sensilla coeloconica subapically. Palpomeres short, apparently lacking sensilla.

Thorax. Antepronotal lobes not narrowed medially, without setae. Acrostichals absent, dorsocentrals uniserial, prealars and scutellars few, supralars absent.

Wing. Membrane bare, with fine punctuation. Anal lobe barely indicated to absent. Costa apically fused with R1 and R2+3, forming a thick clavus well proximal to mid-length of wing; R4+5 thick; “false vein” ending near apex of wing; M1+2 diffuse; Cu1 not sinuous; FCu far distal to RM; postcubitus ending far beyond cubital fork; anal vein ending proximal to FCu. Squama and veins, except costa, bare. Brachiolum with one seta and 10 sensilla campaniformia, five in single group distal to seta and five aligned above setae.

Legs. Foreleg ratio about 1.0. All trochanters with dorsal keel, strongest developed on foretrochanter. Hind tibia with two long spurs, of which one curved; tibial comb normal. Tarsomeres 1–3 of mid- and hind legs with short, curved, strong setae, best developed on ta1. Hind ta1 with row of short, thick setae; ta4 shorter than ta5.

Abdomen. Tergites II–VII and IX each with 1–3 setae, tergite VIII without setae. Sternites without setae.

Hypopygium. Without anal point. Tergite IX with few, weak marginal setae. Laterosternite without setae. Superior volsella absent, inferior volsella broad and low. Virga absent. Gonostylus without crista dorsalis, with simple megaseta. Transverse sternapodeme slightly concave, without oral projections. Phallapodeme with straight distal margin, apically slightly curved posteriad.

Female. Generally similar to male. Wing length about 0.6 mm.

Head. Antenna with five flagellomeres.

Wing. Costa apically fused with R1 and R2+3, forming a thick clavus reaching about mid-length of wing; R4+5 thickened basally, thin distally; “false vein” ending near apex of wing. Sensillum campaniformium present on R-fork (FR).

Leg. Mid ta1 with sensilla chaetica in distal half.

Genitalia. Gonocoxapodeme straight. Gonocoxite well developed, with few setae. Tergite IX with few, weak setae. Cercus very small. Gonapophysis not divided. Apodeme lobe large. Labia apparently fused, rounded, medially notched. Coxosternapodeme with two entwined rami, with few spine-like anterior projections. Seminal capsules larger than cerci; neck placed posteriolaterally; spermathecal ducts with common opening.

Pupa. Small; total length 1.2–1.4 mm.

Cephalothorax. Frontal warts absent. Frontal setae long and strong, on small cephalic tubercles. Postorbital setae two, one of them longer and stronger. Thoracic horn absent. Two median and one lateral antepronotals; three precorneals; four dorsocentrals in two pairs, Dc3 conspicuously longer and stronger than others. Wing sheath with one or two marginal pearl rows, giving the impression of a serrate margin. Wing nose absent.

Abdomen. Tergite I without shagreen; T II–IX with shagreen, posterior shagreen spinules stronger on T II–VII. Conjunctives between T II/III–VI/VII with strong hooklets. Sternite I bare, S II–III bare or with few shagreen points, S IV–VIII with shagreen. Female S VIII with broad, low posterior projection with median suture. Pedes spurii A and B absent. Tergites I and VIII each with three pairs of D-setae, T II with four pairs, T III–VII each with five pairs. Sternite I without V-setae, S II–VII each with four pairs, S VIII with one pair. Segment I with one L-seta, segments II and VI–VIII each with three L-setae, segments III–V each with one anterior, short L-seta and two posterior, long taeniate L-setae. Anal lobe well developed, in apical 1/3 with uniserial fringe of long taeniate setae. Inner margin of anal lobe with non-taeniate setae. Anal lobe ventrally with three taeniate macrosetae with hooked, frequently broken, tips on small tubercles. Genital sacs of both male and female not reaching apex of anal lobe.

Larva. Small; head capsule length about 170 µm.

Head. Cephalic capsule about 1/3 longer than wide, somewhat wedge-shaped. Antenna with five segments, about 1/2 the length of head capsule; with ring organ in proximal half and two antennal "setae" in distal half of first segment. Antennal blade shorter than flagellum, reaching end of second segment. Lauterborn organs very small; style absent. Labrum with S I bifid; S II large, arising from small pedestal; S III small, situated posterior to S I and anterior to S II; S IVA adjacent to S II, S IVB apparently absent or vestigial. Labral rod (LR) present. Pecten epipharyngis consisting of three spines. With two pairs of chaetulae laterales: one median pair and one apically broad and pectinate marginal pair. With two pairs of chaetulae basales. Premandible simple, brush not discernible. Mandible with four inner teeth, apical tooth subequal to distal inner tooth. Seta subdentalis present, seta interna with pectinate branches. Mentum with three median teeth and five pairs of lateral teeth, first lateral pair adpressed to outer median teeth. Ventromental plates reduced.

Abdomen. Anterior parapods with serrated claws. Procercus with four anal setae. Posterior parapod with simple, hooked claws and apically split sub-basal seta. Body setae thin, shorter than 1/2 the width of corresponding segment.

Systematics. The male wing of Ubatubaneura is typical for the Corynoneura -group, having a clavus as described by Saether and Kristoffersen (1996): a retracted and thickened costa together with a thickening of R1 and probably R2+3; R4+5 does not participate in the clavus and does not meet costa. In the males of Physoneura and Notocladius t clavus is different, here R4+5 meets costa.

The shape of the head and the antenna of both male and female Ubatubaneura is unique within the Corynoneura group. The hypopygium of Ubatubaneura resembles that of Thienemanniella ; the transverse sternapodeme is not broadened medially and inverted V- or U-shaped as in Corynoneura . The lateral projections of the transverse sternapodeme and the inferior volsella are not developed as in Onconeura and Tempisquitoneura . The anal point is absent (present in Physoneura ) and megaseta is present (absent in Ichthyocladius ).

Some features of the pupa of Ubatubaneura , as the presence of strong caudal hooklets on the tergal conjunctives and the reduction of the anal fringe and the taeniate lateral setae are shared with Onconeura and Tempisquitoneura . However, these two genera have only one or lack small anal macrosetae, respectively. The presence of three anal macrosetae with hooked tips in Ubatubaneura is shared with Thienemanniella and other orthoclads as well, but the position of this structure on the ventral side of the anal lobe is unique for Ubatubaneura . Mendes et al. (2004) mention that in Ichthyocladius the macrosetae are positioned apical or ventral to tergite IX, but in this genus the anal lobes are strongly reduced.

The larva of Ubatubaneura is very similar to Thienemanniella , lacking the elongated head found in Corynoneura , Tempisquitoneura and Onconeura and the 5-segmented antenna is only about as long as 1/2 the head length. The presence of a bifid SI seems to be a common feature in the Corynoneura group, as it has also been observed in Tempisquitoneura , Notocladius , Thienemanniella (Epler & de la Rosa 1995; Harrison 1997; Schmid 1993), and also in still undescribed species of Onconeura . The apically split sub-basal setae on the posterior parapods are also found in Corynoneura , but this structure has probably been overlooked in other genera.

Ubatubaneura has several characters considered by Schlee (1968) as plesiomorphic within the Corynoneura group: male hind leg with two long tibial spurs, hind tibia not strongly enlarged and elongated, transverse sternapodeme comparatively straight and thin, and gonostylus not curved, with short megaseta. The non-elongated larval head and the short antenna are also considered as plesiomorphic by Schlee (1968).

The phylogenetic relationship of the Corynoneura group was outlined by Mendes et al. (2004) and Andersen and Saether (2005). If the Corynoneura group belongs in the Eukiefferiella group, pupal characters as strong hooklets on the tergites, presence of pearl rows, reduced fringe, and reduced lateral taeniate setae can be considered as plesiomorphic within the group (see Andersen & Saether 2005). This also indicates a basal position of Ubatubaneura within the Corynoneura group.