Simulium (Trichodagmia) Enderlein, 1934

Figs 13–15, 21, 28–30, 45–47, 64–68, 86–88, 104–106, 145–147, 156–157

Trichodagmia Enderlein, 1934a: 288 (as genus). Type species: Trichodagmia latitarse Enderlein, 1934 [= Simulium townsendi Malloch, 1912].

Thyrsopelma Enderlein, 1934a: 284 (as genus). Type species: Thyrsopelma brasiliense Enderlein, 1934 [= Simulium orbitale Lutz, 1910].

Grenieriella Vargas & Díaz Nájera, 1951: 141, figs 14–22 (as subgenus of Simulium). Type species: Grenieriella lahillei Vargas & Díaz Nájera, 1951 [= Simulium lahillei (Paterson & Shannon, 1927)].

Diagnosis

Female

Scutum blackish; scutal pattern present (except in S. orbitale). Cibarium pigmented anteromedially (Figs 13–15), medial area armed with sharp teeth or with tubercle-like prominences. Tarsal claw with or without subbasal tooth. Hypoginial valves subovoid, shorter than sternite VIII width, directed forwardly or inwardly (Fig. 21). Anal lobe subrectangular, being two times longer or shorter than cercus base width.

Male

Ventral plate two times longer than wide, with or without anterior notch; lateral shoulders projected or not; posteromedial process present (except in S. nigrimanum), being cylindrical or globular. Gonocoxite wider than long, with base almost equal or less in width than gonostylus width at their point of intersection (Figs 64–68). Gonostylus hooked-shaped, distinctly longer than gonocoxite, with acute apex, and apical spinule (Figs 64–68). Parameres with very small to absent spines.

Pupa

Cocoon aperture upward directed, separated from substratum, not corbicular (Figs 86–88). Gill shorter than pupa body, with trunk development, free or with the base enclosed by the cocoon anterior margin; with 12–50 filamentous arranged in different planes (tridimensional); filaments stiff or flexible, cylindrical, and with acute apices darkened or not; inferior branch multibranched. Thoracic trichomes simple or multibranched.

Larva (last instar)

Cephalic apotome spots insertion area pigmented. Postocciput extended over the cervical sclerites or not; Antenna ranging from equal or shorter, to longer than labral fan stalk, without secondary annulations. Mandibles with preapical teeth from shorter or as long as the apical tooth; two mandibular serrations of different sizes. Postgenal cleft triangular or rounded; postgenal bridge length less than hypostomal length (Figs 145–147). Hypostoma anterior margin straight; hypostomal teeth extended below or beyond anterior margin of ventral wall of hypostoma; medial tooth as prominent as lateral teeth or reduced; lateral serrations absent or much reduced; paralateral teeth absent. Body surface glabrous or hairy. Abdomen gradually expanding posteroventrally to last segments, then abruptly contracting to posterior proleg. Anal sclerite not encircling base of posterior proleg. Posterior portion of abdomen without sclerotized accessory plates. Without 1+1 ventral tubercles. Rectal papillae with three multi-branched lobes.

Remarks

We recognize S. ( Trichodagmia) (Fig. 1, node 18) just as the Orbitale species-group of S. ( Trichodagmia) sensu Adler (2020), which includes 21 species. So defined, this subgenus was recovered as monophyletic and well supported based on eight synapomorphies (Table 2, node 18). According to the clades found, we divided S. ( Trichodagmia) into two species-groups: Nigrimanum [= S. ( Trichodagmia) s. str. (Fig. 1, node 19)], and Orbitale [= S. ( Thyrsopelma) (Fig. 1, node 20)]. Nigrimanum is comprised of nine species and supported by three synapomorphies (Table 2, node 19). Orbitale is comprised of the remaining seven species and is supported by seven synapomorphies (Table 2, node 20), one of them unique: female cibarium armed with tubercle-like prominences (3 (1)) (Fig. 15).

These two groups are considered as different subgenera by other authors, but previous studies showed its close relationship as recovered here (Coscarón 1987; Miranda-Esquivel & Coscarón 2001). Both speciesgroups can be differentiated by: female tarsal claws, cibarium, hypoginial valves orientation, and anal lobe length; male ventral plate morphology; pupal gills; larval body tegument, antenna, postocciput, and hypostomal teeth orientation.

Simulium (Trichodagmia) includes anthropophilic species with medical-economic importance: Simulium guianense Wise, 1911 is the primary vector of onchocerciasis in the Brazilian Amazonia focus of the disease (Shelley et al. 2010). Simulium nigrimanum Macquart, 1838, is a potential vector of onchocerciasis in the Minaçu focus disease of Brazil (Shelley et al. 2000) and is also suspected to be the responsible for causing endemic pemphigus foliaceus in Brazil, an autoimmune skin reaction in response to the female’s bites (Eaton et al. 1998). Simulium lahillei (Paterson & Shannon, 1927), S. orbitale Lutz, 1910 and S. scutistriatum Lutz, 1909 are nuisance species to humans and cattle (Miranda-Esquivel & Coscarón 2001).

Nigrimanum species-group

Species

Simulium chimguazaense Díaz, Moncada, Lotta, Matta & Adler, 2015

S. huairayacu Wygodzinsky, 1953

S. lahillei (Paterson & Shannon, 1927)

S. muiscorum Bueno, Moncada & Muñoz de Hoyos, 1979

S. nigrimanum Macquart, 1838

S. nunesdemelloi Hamada, Pepinelli & Hernández, 2006

S. sumapazense Coscarón & Py-Daniel, 1989

S. townsendi Malloch, 1912

S. wygodzinskyorum Coscarón & Py-Daniel, 1989

Diagnosis

Female

Tarsal claw with a subbasal tooth shorter than a third of the claw length. Cibarium medial area armed with sharp teeth (Figs 13–14). Hypoginial valves forwardly directed. Anal lobe twice as long as cercus width at base (Fig. 29).

Male

Ventral plate not notched; lateral shoulders not projected; posteromedial process cylindrical with length lower or equal than ventral plate length (Fig. 46).

Pupa

Gills free from cocoon (Fig. 86); filaments with apices concolorous with rest of gill (Fig. 104) (except S. nunesdemelloi). Thoracic trichomes simple.

Larva (last instar)

Antenna equal or shorter than labral fan stalk. Postocciput not extended over the cervical sclerites. Postgenal cleft triangular (e.g., S. huairayacu, S. lahillei (Fig. 146)) or rounded (e.g., S. townsendi, S. nigrimanum (Fig. 147)). Hypostomal teeth arranged beyond anterior margin of ventral wall of hypostoma; medial tooth as prominent as lateral teeth (Fig. 157). Body glabrous.

Distribution

The group is distributed in Argentina, Bolivia, Brazil (southern and central regions), Colombia, Ecuador, Paraguay, Peru, and Venezuela (Adler 2020).

Orbitale species-group

Species

Simulium coscaroni Nascimento, Hamada & Adler, 2017

S. criniferum Nascimento, Hamada, Andrade-Souza & Adler, 2017

S. duodenicornium Pepinelli, Hamada & Trivinho-Strixino, 2005

S. guianense Wise, 1911

S. hirtipupa Lutz, 1910

S. itajara Nascimento, Hamada & Pepinelli, 2020

S. itaunense d’Andretta & Dolores González, 1964

S. jeteri (Py-Daniel, Darwich, Mardini, Strieder & Coscarón, 2005)

S. litobranchium Hamada, Pepinelli, Mattos-Glória & Luz, 2010

S. orbitale Lutz, 1910

S. perplexum Shelley, Maia-Herzog, Luna Dias & Couch, 1989

S. scutistriatum Lutz, 1909

Diagnosis

Female

Tarsal claw without subbasal tooth. Cibarium armed (except in S. hirtipupa) with tubercle-like prominences (Fig. 15). Hypoginial valves inwardly directed (Fig. 21). Anal lobe shorter than the cercus base width (Fig. 28) (exceptions: S. scutistiatum (Fig. 30), S. criniferum, S. itajara).

Male

Ventral plate with a shallow notch (except on S. scutistriatum and S. itajara, which do not have notch, and S. criniferum and S. hirtipupa, in which the notch is deep as half the length of ventral plate body); lateral shoulders projected (Fig. 45) (except in S. scutistriatum (Fig. 47) and S. itajara); posteromedial process cylindrical (e.g., S. hirtipupa, S. scutistriatum (Fig. 47), S. itajara) or globular (e.g., S. criniferum, S. itaunense (Fig. 45), S. orbitale), longer than ventral plate length (except S. scutistiatum (Fig. 47) and S. itajara).

Pupa

Gill base enclosed by cocoon anterior margin (Figs 87–88) with filament apices darkened (Figs 105– 106) (except in S. coscaroni). Thoracic trichomes simples.

Larva (last instar)

Antenna with ½ of distal antennomere surpassing the labral fan stalk. Postocciput extended over the cervical sclerites. Postgenal cleft rounded (Fig. 145). Hypostomal teeth arranged below anterior margin of ventral wall of hypostoma; medial tooth shorter than lateral teeth (Fig. 156). Body covered with multiple setae (e.g., S. scutistriatum and S. itajara).

Distribution

The group is mostly found in Brazil, but with some species also recorded from Colombia, French Guiana, Guyana, Paraguay, Suriname, and Venezuela (Adler 2020).