Simulium (Nevermannia) perforatum Fain & Dujardin, 1983

Krüger, Andreas, 2016, The Simulium nigritarse subgroup (Diptera: Simuliidae) in Uganda: New species and country records, Zootaxa 4121 (1), pp. 59-67 : 63-64

Simulium (Nevermannia) perforatum Fain & Dujardin, 1983

( Figs. 1 B, 3C, 4A–C)

Since in the short original description Fain & Dujardin (1983) used only pharate adults dissected from their pupae, no adult colour features were provided. These and further morphological data are for Ugandan specimens as follows:

Medium-sized species, wing length 3–3.5 mm.

Female. Except of the dark setae of wing tufts and basicosta very similar to S. bwambanum sp. nov. Colour patterns of the legs as typical for S. nigritarse s. l. Tarsal claws with a large basal tooth. Sensory vesicle (Lutz’s organ) broad, more than half of the length of the third palpal segment ( Fig. 1 B).

Male. Similar to females except for sexual differences. Setae of wing tufts and basicosta dark. Hind femur mainly dark, only basally brownish. Basal third of hind tibia yellow. Hind basitarsus slightly more dilated than in the other two species, length to width ratio 3.08–3.46 (mean 3.28, n=5). Terminalia of the general S. nigritarse s. l. type, with two pairs of strongly unequal parameral hooks, and the style distinctly shorter than the coxite ( Fig. 4 A).

Pupa. As originally described by Fain & Dujardin (1983). Cocoon loosely woven with perforations and fenestrations ( Fig. 4 B). The configuration of the four gill filaments ( Fig. 3 C) very similar to that of S. bwambanum sp. nov., also resembling that of S. arabicum . Upper pair of filaments with a short common stalk, which is slightly longer than in S. bwambanum sp. nov. Structure of the filament walls intermediate between types 1 and 2, as in S. bwambanum sp. nov. (see Fig. 2 B). The shape of the basal vesicle ( Fig. 3 C, 4C) is indistinguishable from that of S. bwambanum sp. nov., i.e. intermediate between types 2 and 3. Pilous plate with normal setae.

Larva. Unknown.

Specimens examined (all emerged from pupae). 1 ♀, Bundibugyo district, Bemara river, 849 m, 0°42´25´´N 30°4´40´´E, 10.viii.1991, leg. R. Garms; 1 ♀, Kabarole district, Kamotonga near confl. Nyakibuguta, 1270 m, 0°51´N 30°27´15´´E, 7.viii.1995, leg. R. Garms; 4 ♀, 4 Ƌ, Kabarole district, Mahoma river at Mitandi road, 1829 m, 0°36´30´´N 30°8´49´´E, 1.viii.1991, leg. R. Garms; 1 Ƌ, same but 2.viii.1991; 1 ♀, Bundibugyo district, Humiya river, 728 m, 0°45´41´´N 30°2´52´´E, 10.viii.1991, leg. R. Garms; 11 ♀, 6 Ƌ, Kabarole district, Dunga river at Mitandi road, 1704 m, 0°37´25´´N 30°9´26´´E, 1.viii.1991, leg. R. Garms; 2 ♀, Kabarole district, Igogonya river, 1158 m, 0°51´20´´N 30°23´44´´E, 23.ix.1993, leg. R. Garms; 10 ♀, 13 Ƌ, Kabarole district, Mpanga river at Mitandi road, 1631 m, 0°39´54´´N 30°10´39´´E, 1.viii.1991, leg. R. Garms.

Distribution. S. perforatum was hitherto only known from Burundi, Rwanda and Zaïre ( Fain & Dujardin, 1983), but is considered to be the most common species of the Nigritarse subgroup in western Uganda. Breeding places in several rivers in the districts Bundibugyo and Kabarole at altitudes from 730 to 1830 m. Always found sympatric with S. bwambanum sp. nov., except apart from the Ruwenzori range in river Igogonya draining into the Rift valley and river Kamotonga in the Itwara forest reserve. The distribution in the latter overlaps with that of S. itwariense sp. nov. At some places sympatric with S. damnosum s. l., S. dentulosum , S. unicornutum , S. hirsutum and S. tentaculum Gibbins. Water temperatures (other than for S. bwambanum sp. nov.): Humiya 18.5°C, Igogonya 17.8°C.

Figures

FIGURE 1. Sensory vesicle (Lutz’s organ) in the 3 rd palpal segment of females. A— Simulium bwambanum sp. nov.; B— S. perforatum; C— S. itwariense sp. nov. Scale bar: A – C = 0.02 mm.

FIGURE 2. Simulium bwambanum sp. nov., pupa. A—cocoon with pupal case, lateral view; B—gill filament wall structure type 1 / 2, below view of surface, above longitudinal view; C—basal trunk of gill. BV—basal vesicle. Scale bar: C = 0.1 mm.

FIGURE 3. Basal aspects of pupal gills. A, B— Simulium bwambanum sp. nov.; C— S. perforatum; D— S. itwariense sp. nov. Scale bar: A – D = 0.5 mm. BV—basal vesicle; PP—pilous plate (approximate location).

FIGURE 4. Simulium perforatum. A—male coxite and style; B—cocoon, lateral view; C—basal trunk of gill. Scale bars: A = 0.1 mm; C = 0.1 mm.