Nilothauma aleta Roback, 1960

Pinho, Luiz Carlos & Andersen, Trond, 2021, Neotropical Nilothauma Kieffer, 1921 (Diptera, Chironomidae): Key, eleven new species, re-descriptions, new combination and new records, ZooKeys 1033, pp. 81-125 : 81

Nilothauma aleta Roback, 1960 Figures 1A, B , 17B

Additional material.

1 male, slide-mounted: Brazil, São Paulo, São Luís do Paraitinga, PE Serra do Mar, Nucleo Santa Virginia , trilha Poco do Pito , afluente Paraibuna , 23°20'09"S, 45°08'46"W, 15.ix.2006, light trap, M.R. Spies & A.E. Siegloch leg.

Diagnostic characters.

The male can be distinguished from its congeners by the combination of: tergite IX without setose dorsal lobe(s); gonostylus stout; acrostichals absent; anal point wide, covering most setae along posterior margin of tergite IX; inferior volsella slender.

Re-description.

Male imago (n = 1). Total length 3.58 mm. Wing length 2.00 mm. Total length/wing length 1.79. Wing length/length of profemur 2.25.

Colouration. Head, thorax and abdomen brown; legs pale, except for ring of brown pigmentation in distal 1/2 to 2/3 of fore- and hind femora, in distal 1/3 of foretibia, in basal 1/8 of mid- and hind tibiae and in distal 1/3 of each tarsomere. Wing membrane apparently hyaline, but faint brown markings are visible when dark-field filter is applied.

Antenna. AR = 0.27. Thirteenth flagellomere 197 µm long.

Head. Temporal setae 7 in single row. Clypeus with 25 setae. Tentorium 123 µm long, maximum width 25 µm. Stipes not measurable. Palp segment lengths (in µm): 39, 34, 123, 147, 191. Third palpomere with 2 sensilla clavata subapically, longest 20 µm long. Fifth palpomere/third palpomere 1.55.

Thorax. Dorsocentrals 12 in single row, acrostichals absent, prealars 3. Scutellum with 6 setae.

Wing. VR = 1.50. Brachiolum with 1 seta, R with 13 setae, R1 with 18 setae, R4+5 with 21 setae, remaining veins bare.

Legs. Spur of fore tibia 44 µm long including 15 µm long scale. Mid-tibia with 1 spur, 15 µm long; hind tibia with 2 spurs, 25 and 29 µm long. Combs of both mid- and hind tibia 20 µm long. Width at apex of fore-tibia 39 µm, of mid-tibia 34 µm, of hind tibia 44 µm. Lengths and proportions of legs as in Table 1 .

Hypopygium (Fig. 1A, B ). Tergite IX without lobes, tapering to apex, with 22 short setae underneath anal point. Anal point lanceolate, 50 µm long, maximum width 37 µm. Tergite bands well developed. Laterosternite IX without setae. Phallapodeme 70 µm long; transverse sternapodeme 55 µm long. Gonocoxite 134 µm long. Inferior volsella straight, 52 µm long, 7 µm wide medially, with microtrichia and 8 simple setae apically. Superior volsella pediform, 17 µm long, 7 µm wide at base, covered with microtrichia and with 2 setae apically. Median volsella 7 µm long, with 2 simple setae, longest 12 µm. Gonostylus 95 µm long, straight. HR = 1.42. HV = 3.77.

Female adult and immatures.

Unknown.

Remarks.

Roback (1960) described Nilothauma aleta Roback, 1960 and N. duena Roback, 1960 from the Peruvian Amazon. In their revision of Nilothauma , Adam & Sæther, (1999) regarded the two species as not belonging to Nilothauma since they lack any projections on tergite IX and stated that they appear to belong in Paratendipes Kieffer. Later, Mendes and Andersen (2009) placed Neelamia Soponis and Paranilothauma Soponis as synonyms of Nilothauma and several new Neotropical species have been described demonstrating the large morphological variation in the genus. Mendes and Andersen (2009) emended the diagnosis of Nilothauma and both N. aleta and N. duena fit well into this diagnosis.

Distribution

(Fig. 17B ). The species was originally described from the Department of Huánuco, in the Peruvian Amazon by Roback (1960); the range is now extended to Serra do Mar ( São Paulo State), in the Brazilian Atlantic Forest.

Figures

Figure 1. Nilothauma aleta Roback, 1960, adult male A hypopygium, dorsal view B hypopygium with anal point and tergite IX removed, dorsal aspect to the left and ventral aspect to the right.

Figure 17. Distribution maps of Neotropical Nilothauma species A N. fittkaui (Soponis, 1987), N. amazonense Mendes & Andersen, 2009 B N. aripuanense Mendes & Andersen, 2009, N Nilothauma aleta Roback, 1960 C N. reissi (Soponis, 1987), N. soka Andersen, Bello-Gonzalez & Hagenlund, 2016 D N. anamariae Dantas & Hamada, 2017, N. jaraguaense Mendes & Andersen, 2009.