Simulium nunesdemelloi Hamada, Pepinelli & Hernández, new species

Female (Figs. 1–22). General color brownish; lateral body length (from anterior region of head to abdominal apex) 2.09 mm (n = 1); lateral thorax length (from neck to wing base) 0.56–0.62 mm (n = 2). Wing length 2.16–2.21 mm (n = 2), width 0.96 mm (n = 2).

Frons, clypeus, and occiput with silvery blue pruinosity; frons longer than wide (Fig. 5); fronto-ocular suture absent, fronto-ocular triangle small, as in Fig. 7. Antenna (Fig. 8) length 0.91–0.99 mm, with silver pubescence; pedicel, scape, and first flagellomere brownish yellow, following flagellomeres increasingly dark brown. Palpus dark brown; sensory vesicle length approximately 1/3 length of palpomere III, with wide mouth (Fig. 15), palpomere V 1.4 times as long as palpomere III and 1.6 times as long as palpomere IV. Mandible with 2 or 3 weak, external serrations and 25–28 internal teeth (n = 2). Lacinia with 25–30 retrorse teeth (n = 2). Cibarium with sclerotized cornuae, medial area with strong and sharp teeth (Figs. 13, 14). Scutum dark brownish orange (Figs. 1–3); independent of light incidence, scutum with 1 median and 1+1 submedian dark longitudinal thin bands, extending from anterior to posterior region (Figs. 1, 2); covered with silver hairs, clumped in small groups (Fig. 6). Anepisternum and katepisternum light brown. Scutellum brownish orange, with golden and dark brown hairs; postnotum brown. Costa with spines and setae, Sc and base of R bare, with exception of 1 female with 1 seta on distal region of Sc (Fig. 4). Foreleg (Fig. 9) with coxa, trochanter, and femur light brown; tibia, basitarsus, and tarsomeres I–IV brown. Middle leg (Fig. 10) with coxa, trochanter, and femur light brown; tibia brown; basitarsus mostly whitish, except small portion distally, brown; tarsomere I whitish basally, remainder brown, tarsomeres II–IV brown. Hind leg (Fig. 11) with coxa, femur, and tibia brown; trochanter and basal 2/3 of basitarsus light brown, distal 1/3 brown; tarsomeres I–IV dark brown, except base of tarsomere I light brown; calcipala as broad as long, reaching pedisulcus. Tarsal claws with subbasal tooth (Fig. 12). Femora and tibiae of middle and hind legs with narrow scale-like setae. Basal fringe of abdomen with short, brownish golden hairs. Tergite II with silver pruinosity (best seen in lateral view); tergites VI–VIII shiny brown. In lateral view, cercus with apex wider than its base (Figs. 18, 20), anal lobe subtriangular (Fig. 20); in ventral view, in situ, as in Fig. 16, after clearing as in Fig. 17. Cercus with internal, membranous folded region in ventral view (Figs. 16, 17) and lateral view (Figs. 18, 20). Hypogynial valves (Fig. 21) not sclerotized, subrectangular, with microtrichia, valves widely separated. Genital fork (Fig. 19) with stem long, lateral arms forming V-shape at junction with main stem, apodemes strong. Spermatheca subspherical, with cuticular microspines (Fig. 22); spermathecal duct and area of attachment unpigmented.

Male (Figs. 23–34). General body color brownish, body length 2.0– 2.4 mm (n = 2); lateral thorax length (from neck to anterior region of wing insertion) 0.41–0.54 mm (mean = 0.47, SD = 0.06, n = 3). Wing length 2.3 mm (n = 1), width 0.9 mm (n = 1).

Antenna (Fig. 28) length 0.43–0.47 mm; pedicel and scape brownish yellow, flagellomeres increasingly dark. Palpus (Fig. 29) brown, palpomere V about 1.94 times as long as palpomere III and 1.85 times as long as palpomere IV; sensory vesicle small, subspherical, approximately 1/4 length of palpomere III. Scutum brownish-orange (Figs. 23–26), with 3 dark longitudinal thin bands running from anterior to posterior region (Figs. 23–25); covered with golden hairs, clumped in small groups (Figs. 23–26).

Anepisternum and katepisternum light brown. Scutellum brownish-orange (Figs. 23–25) with thin golden hairs; with posterior light (Figs. 24, 25), with thin, dark band in central region. Postnotum black with silver pruinosity. Wing with Sc and base of R bare (Fig. 27). Legs with same color pattern as in female. Abdominal tergites black; basal fringe with thin, long, black hairs and golden highlights; tergites II–VII with silver pruinosity. Gonocoxite and gonostylus (Fig. 31) dark brown, gonocoxite wider than long; gonostylus almost double gonocoxite length, longer than wide, bearing 1 or 2 spinules (Figs. 33, 34). Ventral plate (Fig. 32), in ventral view, longer than wide, subrectangular, with domeshaped keel. Median sclerite not seen. Paramere and aedeagal membrane as in Fig. 30.

Pupa (Figs. 35–45). Mean length 2.4 mm (SD = 0.2, n = 5). Cocoon (Figs. 35–38) boot-shaped. Mean length along dorsal surface 2.5 mm (SD = 0.1, n = 5). Head projecting downward, with 3 pairs of trichomes, 1 frontal pair, 3–5 branched, longer than 2 dorsal simple or bifid pairs (Fig. 41); tubercles absent or scarce on dorsal region, mostly present on facial region. Gill with 19 or 20 thick filaments, varying in length and thickness (Figs. 39, 40), distributed in 3 dimensions (Fig. 36), and with sclerotized distal end (Fig. 43).

Thorax almost without tubercles, some rounded and pointed tubercles present on posterior region of thorax and on area below trunk of gill filaments. Five pairs of 2–4 branched trichomes (Fig. 42) and 1 pair of bifid, thick, long lateral trichomes. Abdomen as in Figs. 44, 45. Tergite I with 1 + 1 setae sublaterally. Tergite II with 4 + 4 stout, short setae. Tergites III and IV with 4 + 4 anteriorly directed hooks on posterior margin. No comb-like spines present on tergites. Sternites III–VIII with anterior group of microspines; sternites V–VII with 2 + 2 long hooks.

Larva (final instar) (Figs. 46–56). Mean body length 6.2 mm (SD = 0.71, n = 5); head capsule, mean lateral length 0.50 mm (SD = 0.02, n = 5). General coloration variable, from light (Fig. 49) to dark grayish green (Fig. 50) (in Carnoy's solution). Head capsule (in dorsal view) with dark region on midline and along basal margin (Fig. 46), with small, simple setae. Cervical sclerites small, elliptical, free in membrane (Fig. 52). Postgenal cleft (Fig. 48) wide and round, postgenal bridge 0.57 times as long as hypostoma. Subesophageal ganglion slightly pigmented (Fig. 47). Antenna (Fig. 51) as long as labralfan stalk; medial article longer than distal and proximal articles, distal article longer than proximal article, proportions of articles (proximal to distal, excluding apical sensillum) 1: 1.4–1.75: 0.8–0.9. Labral fan with 41–43 primary rays. Hypostoma (Fig. 53) with 9 teeth, median tooth and sublateral teeth not well differentiated; hypostoma lateral margin with 2 paralateral teeth and 3–5 lateral serrations per side; with 4–6 sublateral setae per side. Lateral mandibular process not seen; mandibular teeth: 1 apical, 2 small external; 3 subapical (first subequal to third and both smaller than second, or all subequal), 6 or 7 internal teeth; 1 mandibular serration and 1 small mandibular sensillum (sensu Craig & Craig 1986). Body with simple setae on dorsal region of abdomen; ventral tubercles absent. Gill histoblast in situ (Fig. 49) large, with sclerotized distal end of filaments pointing toward ventral region of body; gill histoblast dissected with 19 or 20 filaments. Arms of anal sclerite as in Fig. 55, anterior arms 0.3 times as long as posterior arms, associated with some thin and few enlarged setae. Posterior circlet bearing 143–150 rows (n = 2) with 21–24 hooks (n = 4). Rectal papilla with 3 branches (Fig. 54), each with approximately 29 or 30 finger-shaped lobes.

Holotype. Male (M), collected in the Rio Negro, São Gabriel da Cachoeira County, 0 0o 10’S, 67o01’W, collectors N. Hamada, R.L.M Ferreira & L. Aquino, 08/X/1998 (INPA).

Paratypes. Same locality and collectors as holotype, 10 pupae (P), 2 larvae (L), 08/X/ 1998 (INPA); 8 P, 3/X/1998 (INPA); same locality as holotype, collectors N. Hamada & R. Ale-Rocha 10 L, 11/XI/1999 (INPA); 3 P, 4 L (INPA), 3 P (BMNH), 1 F (pinned), 1 F (on slide), 2 M (pinned), 1 M (on slide), collectors N. Hamada & R. Ale-Rocha, 16-17/XI/ 1999, Rio Tiquié, Pari Cachoeira Community, 0 0o 13’N, 69o40’W, Coll. N. Hamada & R.

Ale-Rocha, 10 L, 2 P, 12/XI/1999, (INPA).

Etymology. This species is named in honor of Professor José Alberto Sampaio Nunes de Mello, a dear friend and former Master’s dissertation advisor of N. Hamada and one of the pioneers in black fly studies at INPA, in the Amazon region.

Diagnosis and taxonomic discussion. We do not include S. nunesdemelloi in any subgenus within the Simuliidae because it shares characters with Trichodagmia and Thyrsopelma . The male and female of the new species are similar to those of S. scutistriatum Lutz and S. nigrimanum Macquart. The males of all of these species have a ventral plate without a developed central region (Fig. 32), and the females have a subtriangular anal lobe with microtrichia (Figs. 16, 20). However, these species can be distinguished in the pupal stage by the number of pupal gill filaments: 19 or 20 in S. nunesdemelloi, 12 in S. scutistriatum, and 18 in S. nigrimanum . In this respect, S. nunesdemelloi is most similar to S. orbitale but the gill filaments are much thicker and more crenulated (Figs. 39–40) than those of S. orbitale . Also, the cephalic and thoracic trichomes of the new species are not spiniform (Figs. 41–42) as in S. orbitale . Based on Coscarón (1991) and Miranda Esquivel & Coscarón (2001), the following combination of characters can distinguish larvae of S. nunesdemelloi n. sp. from those of other species with known larvae in the subgenera Thyrsopelma and Trichodagmia: absence of racketshaped scales on the dorsal region of the abdomen, rounded postgenal cleft (Fig. 48), dissected histoblast with 19 or 20 gill filaments with heavily sclerotized tips, and in situ histoblast with gill filament tips pointing toward the ventral region of the body (Fig. 49).

Bionomics. This species was not collected biting humans during the fieldwork. Larvae and pupae were collected in forested areas, in large rivers (Rio Negro and Rio Tiquié, with widths of 1.65 km and 70 m, respectively), on Podostemaceae leaves growing on rocky substrate in highly turbulent water and, usually, at depths below 0.5 m. River-water temperature was approximately 26o C, pH 4.5–5.2 and electrical conductivity less than 10 ΜS/cm. Immatures of S. orbitale also use Podostemaceae leaves as substrate. But usually the new species is collected in low density, whereas S. orbitale is collected in high density and nearer the surface. Most of the collected pupae of S. nunesdemelloi n. sp. had a silk mesh covering the opening of the cocoon (Figs. 37, 38); the mesh holds the larval exuviae inside the cocoon.