Nilothauma involucrum, 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 : 24-25

Nilothauma involucrum sp. n.

( Figs 30–32 )

Type material. Holotype male, BRAZIL: Espírito Santo: Linhares, Reserva Biológica Sooretama, 18º58'03.0''S, 40º07'56.8''W, 33 m a.s.l., 21–24.iii.2002, Malaise trap (Bosque 2), C. O. Azevedo et al. (BIOTA-FAPESP) ( MZUSP).

Diagnostic characters. The absence of dorsal lobe(s) on tergite IX and anal point combined with a superior volsella with ventral, median fold and curved posterior margin with strong microtrichia will separate the male of N. involucrum from all other Nilothauma species.

Etymology. From Latin, involucrum , meaning envelope, referring to the shape of the superior volsella.

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

Coloration. Thorax, legs and antenna uniformly pale brown.

Head. AR 0.21. Thirteenth flagellomere 83 µm long; stout subapical seta 58 µm long. Temporal setae 7 in single row including 2 inner verticals, 4 outer verticals, and 1 postorbital. Frontal tubercles present. Clypeus with 14 setae. Tentorium 54 µm long, 7 µm wide. Stipes 68 µm long. Palp segment lengths (in µm): 14, 18, 45, 70, 90. Third palpomere with 2 sensilla clavata subapically, longest 14 µm long. Fifth palpomere / third Thorax. Antepronotal lobe with weak dorsal notch. Dorsocentrals 5 in single row, acrostichals 8, prealars 2. Scutellum with 2 setae.

Wing. Lost.

Legs. Spur of foretibia 50 µm long including 25 µm long scale. Midtibia with 1 spur, 27 µm long; hind tibia with 2 spurs, 34 µm and 18 µm long. Combs of midtibia 14 µm long, of hind tibia 11 µm long. Width at apex of foretibia 28 µm, of midtibia 32 µm, of hind tibia 36 µm. Lengths and proportions of legs as in Table 6.

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

Hypopygium ( Figs 30–31 ). Tergite IX with subrectangular posterior margin, with 11 setae. Anal point absent. Laterosternite IX with 1 seta. Phalapodeme 34 µm long; transverse sternapodeme 23 µm long. Gonocoxite 61 µm long. Inferior volsella 57 µm long, 11 µm wide at base, 8 µm wide at apex, curved with rounded apex, with microtrichia and about 10 setae subapically, all simple. Superior volsella ( Fig. 32 ) 29 µm long, 28 µm wide medially, dorsally with median ridge, ventrally with median fold and curved posterior margin with strong microtrichia. Median volsella apparently fused with superior volsella. Gonostylus 100 µm long, weakly curved, widest in apical 1/2, all setae hair-like. HR 0.61, HV 1.53.

Female and immatures. Unknown.

Distribution. Known only from the type locality in Espírito Santo State, Brazil.

Figures

FIGURES 30 – 32. Nilothauma involucrum sp. n., male. 30 — dorsal aspect of hypopygium. 31 — hypopygium, ventral view. 32 — superior volsella, ventral view.