Nilothauma longissimum, Mendes, Humberto Fonseca & Andersen, Trond, 2009

Mendes, Humberto Fonseca & Andersen, Trond, 2009, Neotropical Nilothauma Kieffer, 1921, with the description of thirteen new species (Diptera: Chironomidae), Zootaxa 2063, pp. 1-45 : 26-28

Nilothauma longissimum sp. n.

( Figs 37–40 )

Type material. Holotype male, BRAZIL: São Paulo: Ubatuba, Parque Estadual Serra do Mar, Núcleo Picinguaba, afluente Rio Fazenda, 10.ix.2006, at light, M. Spies & A. E. Siegloch ( MZUSP). Paratypes: 1 male, as holotype; 1 male, as holotype except for afluente Rio Cambori, 09.ix.2006 ( MZUSP, ZMBN).

Diagnostic characters. The absence of dorsal lobe(s) on tergite IX and anal point combined with the high antennal ratio (AR> 1.00) and the subrectangular superior volsella will separate the male of N. longissimum from all other Nilothauma species.

Etymology. From Latin, longissimus, meaning longest, as this is the only species of the genus with an AR higher than 1.00.

Male (n = 2–3, except when otherwise stated). Total length 2.04–2.67 mm. Wing length 1.21–1.34 mm. Total length / wing length 1.69–1.99. Wing length / length of profemur 1.87–1.90.

fe ti ta1 ta2 ta3 ta4

p1 635–718 387–589 746–801 332–363 225–258 147–166 p2 654–728 470–516 280–451 129–184 83–111 46–74 p3 737–792 553–599 479 203 147–157 74–83

ta5 LR BV SV BR

p1 50–64 1.26–1.93 2.31–2.49 1.37–1.69 3.6–3.9 p 2 28–37 0.60–0.87 4.18–4.62 2.75–4.00 4.3–5.7 p 3 28–37 0.80–0.87 3.69–4.14 2.69–2.90 5.3–6.0

Coloration. Thorax, legs and antenna uniformly pale brown, abdominal segments with dark oral bands.

Head. AR 1.07–1.12. Thirteenth flagellomere 410–436 µm long, stout subapical seta lost in all specimens. Temporal setae 8–10 in single row including 3–6 inner verticals, 2–3 outer verticals and 2 postorbitals. Frontal tubercles absent. Clypeus with 11–14 setae. Tentorium 102–109 µm long, 15–17 µm wide. Stipes 98–107 µm long. Palp segment lengths (in µm): 20–23, 32–34, 82–86, 95, 141 (1). Third palpomere with 4–5 sensilla clavata subapically, longest 13–16 µm long. Fifth palpomere / third palpomere 1.72 (1).

Thorax. Dorsocentrals 8–12 in single row; acrostichals 7–9, biserial; prealars 2. Scutellum with 4–6 setae.

Wing. VR 1.25–1.34. Brachiolum with 2 setae, R with 5–8 setae, R4+5 with 1–3 setae apically, remaining veins bare.

Legs. Spur of foretibia 48–57 µm long including 15–20 µm long scale. Midtibia with 1 spur, 54–59 µm long; hind tibia with 2 spurs, 57–66 µm and 23 (1) µm long. Combs of midtibia 14 µm long, of hind tibia 14–17 µm long. Width at apex of foretibia 42–54 µm, of midtibia 54–59 µm, of hind tibia 45–50 µm. Lengths and proportions of legs as in Table 8.

Abdomen. Tergites with few setae. Segment VIII long, weakly triangular, tapering anteriorly.

Hypopygium ( Figs 37–38 ). Tergite IX with subrectangular posterior margin, without setae. Anal point absent. Laterosternite IX with 1 seta. Phalapodeme 54–66 µm long; transverse sternapodeme without oral projections, 19–29 µm long. Gonocoxite 102–107 µm long. Inferior volsella 52–75 µm long, 9 µm wide at base, 10–18 µm wide subapically; curved with broadly rounded apex; with microtrichia; with row of 5–8 stout, almost lanceolate setae subapically and 2–3 simple weak setae apically. Superior volsella ( Fig. 39 ) subrectangular, 27–48 µm long, 38–48 µm wide, with 15 µm wide base which appears flexible in dorsoventral direction, covered with microtrichia, with 14–18 marginal setae. Median volsella ( Fig. 40 ) tubercle-like, 4–8 µm long, with 2–3 long, simple setae. Gonostylus 102–118 µm long, curved, tapering from base, all setae hair-like. HR 0.90–1.00, HV 2.00–2.26.

Female and immatures. Unknown.

Distribution. Known only from the type locality in São Paulo, Brazil.

Figures

FIGURES 37 – 40. Nilothauma longissimum sp. n., male. 37 — dorsal aspect of hypopygium. 38 — hypopygium with tergite IX and anal point removed, dorsal view left, ventral view right. 39 — superior volsella, dorsal view. 40 — median volsella, dorsal view.