Nilothauma amazonense, 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 : 13-15

Nilothauma amazonense sp. n.

( Figs 6–8 )

Type material. Holotype male, BRAZIL: Amazonas: Rio Negro - Rio Itu, 14.ii.1962, drift net, E. J. Fittkau ( ZSM).

fe ti ta1 ta2 ta3 ta4 ta5 LR BV SV BR p1 259 151 245 90 72 54 32 1.62 2.64 1.68 – p2 270 191 90 32 25 18 14 0.47 6.12 5.12 – p3 288 263 133 58 79 40 29 0.51 3.33 4.13 –

Diagnostic characters. The two dorsal, setose lobes on tergite IX combined with a lanceolate anal point, pediform superior volsella, well developed median volsella, inferior volsella and gonostylus with simple setae, and hind ta2 shorter than hind ta3 will separate the male of N. amazonense from all other Nilothauma species.

Etymology. Named after the Amazonas State.

Male (n = 1). Total length 1.53 mm.

Coloration. Thorax, legs and antenna uniformly pale brown.

Head. AR 0.14. Thirteenth flagellomere 43 µm long; stout subapical setae 40 µm long. Temporal setae at least 2 in single row. Frontal tubercles apparently absent. Clypeus with at least 5 setae. Tentorium 79 µm long, 11 µm wide. Stipes not measurable. Palp segment lengths (in µm): 11, 11, 59, 68, 77. Third palpomere with 3 sensilla clavata subapically, longest 9 µm long. Fifth palpomere / third palpomere 1.31.

Thorax. Dorsocentrals and prealars not discernable, acrostichals 7. Scutellum with 2 setae.

Wing. Not measurable.

Legs. Spur of foretibia 25 µm long including 11 µm long scale. Midtibia with 1 spur, 20 µm long; hind tibia with 2 spurs, 18 µm and 25 µm long. Combs of midtibia 14 µm long, of hind tibia 12 µm long. Width at apex of foretibia 20 µm, of midtibia 20 µm, of hind tibia 25 µm. Lengths and proportions of legs as in Table 1.

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

Hypopygium ( Figs 6–7 ). Tergite IX with subrectangular posterior margin, with 4–5 strong setae on each side close to base of anal point, with pair of dorsal lobes anteriolaterally, each with 7–8 long setae. Anal point lanceolate, 20 µm long, 9 µm wide medially. Laterosternite IX with 1 seta. Phalapodeme 25 µm long; transverse sternapodeme 9 µm long, lacking oral projections. Gonocoxite 79 µm long. Inferior volsella 43 µm long, 7 µm wide at base, 8 µm wide at apex, nearly straight with rounded apex, with microtrichia and 4 strong, subapical to apical setae sitting on small tubercles, all setae simple and curved. Superior volsella ( Fig. 8 ) pediform, 18 µm long, 4 µm wide at base, 3 µm wide at apex, slightly inclined in relation to gonocoxite, covered with microtrichia. Median volsella ( Fig. 8 ) 7 µm long, without basal setae and microtrichia, with 2 apical setae sitting on small tubercles. Gonostylus 57 µm long, slightly wider in apical 1/2, all setae hair-like. HR 1.40, HV 2.68.

Female and immatures. Unknown.

Distribution. Known only from the type locality in the Amazonas, Brazil.

Figures

FIGURES 6 – 8. Nilothauma amazonense sp. n., male. 6 — dorsal aspect of hypopygium. 7 — hypopygium with tergite IX and anal point removed, dorsal view left, ventral view right. 8 — median and superior volsella, dorsal view.