Simulium (Hemicnetha) Enderlein, 1934

Figs 9–12, 19–20, 26, 41–42, 60–62, 80–81, 99–102, 111, 122–123, 140–143, 153–154

Hemicnetha Enderlein, 1934b: 190 (as genus). Type species: Hemicnetha mexicana Enderlein, 1934 [= Simulium paynei (Vargas, 1942) (subst. name) nom. nov.]

Dyarella Vargas, Martínez Palacios & Díaz Nájera, 1946: 105, figs 8–28 (as subgenus of Simulium). Type species: Simulium mexicanum Bellardi 1982 [= Simulium tarsatum Macquart, 1846 (1844)].

Species

Simulium brachycladum Lutz & Pinto, 1932

S. bricenoi Vargas, Martínez Palacios & Díaz Nájera, 1946

S. cristalinum Coscarón & Py-Daniel, 1989

S. earlei Vargas, Martínez Palacios & Díaz Nájera, 1946

S. freemani Vargas & Díaz Nájera, 1949

S. guerrerense Vargas & Díaz Nájera, 1956

S. hieroglyphicum Peterson, Vargas & Ramírez-Pérez, 1988

S. hinmani Vargas, Martínez Palacios & Díaz Nájera, 1946

S. hippovorum Malloch, 1914

S. lobatoi Luna Dias, Hernández, Maia-Herzog & Shelley, 2004

S. paynei Vargas, 1942

S. pulverulentum Knab, 1915

S. rubrithorax Lutz, 1909

S. smarti Vargas, 1946

S. solarii Stone, 1948

S. tarsale Williston, 1896

S. tarsatum Macquart, 1846

S. virgatum Coquillett, 1902

S. yepocapense Dalmat, 1949 .

Diagnosis

Female

Scutum black to dark brown (e.g., S. pulverulentum, S. earlei, S. hieroglyphicum, S. bricenoi, S. tarsatum) or red to light brown (e.g., S. brachycladum, S. cristalinum, S. lobatoi, S. paynei, S. rubrithorax, S. virgatum); scutal pattern present. Cibarium unpigmented anteromedially, armed with sharp teeth (Figs 9–10, 12) or unarmed (Fig. 11). Tarsal claw with subbasal tooth shorter than a third of claw length (except in S. lobatoi, in which the tooth has about half of claw length). Hypoginial valves fine and pointed (Fig. 19) or subtriangular (Fig. 20), longer than sternite VIII width (except in S. lobatoi, in which are shorter), forwardly directed. Anal lobe subrectangular (except in S. lobatoi, in which is hemispheric with curved distal border), twice as long as cercus width at base. (Fig. 26).

Male

Ventral plate two times longer than wide or with sub-equal width and length, not notched (except in S. arlei); lateral shoulders absent (Fig. 42) or present (Fig. 41), in this case, not projected (except in S. lobatoi); posteromedian process absent (Fig. 42) or present (Fig. 41), in this case, is cylindrical and longer than ventral plate width (except in S. lobatoi, in which is smaller). Gonocoxite longer than wide, with base almost equal in width to gonostylus width at their point of intersection (Figs 60–62). Gonostylus cylindrical, with medial region wider than basal region; distinctly longer than gonocoxite, with blunt apex and apical spicule (Figs 60–62). Parameres with both distinctly large and small accessory spines.

Pupa

Cocoon aperture upward directed (Figs 80–81),separated from substratum, corbicular (Fig.81) or not. Gill shorter than pupa body, with trunk developed and base enclosed by cocoon anterior margin (Figs 80–81) (except in S. lobatoi, in which the gills are totally free); with 6–90 filaments arranged in different planes (tridimensional); filaments flexible, cylindrical, with apices blunt (e.g., S. hieroglyphicum, S. bricenoi, S. paynei, S. rubrithorax, S. virgatum, S. tarsatum) or acute (e.g., S. brachycladum, S. cristalinum, S. lobatoi, S. pulverulentum, S. earlei), concolorous with rest of gill; inferior branch multi-branched (Figs 99–100) or single-branched (Figs 100–101). Thoracic trichomes generally simple.

Larva (last instar)

Cephalic apotome spots insertion area pigmented (Figs 122–123) (except in S. lobatoi). Postocciput extended (Fig. 122) over the cervical sclerites, or not (Fig. 123). Antenna ranging from equal in length to or shorter than labral fan stalk (e.g., S. earlei, S. bricenoi, S. paynei, S. rubrithorax, S. tarsatum), to longer (e.g., S. brachycladum, S. cristalinum, S. lobatoi, S. pulverulentum, S. hieroglyphicum), without secondary annulations. Mandibles with preapical teeth as long as apical tooth; two mandibular serrations of different sizes. Postgenal cleft triangular; postgenal bridge length less than hypostomal length (Figs 140–143). Hypostoma anterior margin convex (Fig. 154) or straight (Fig. 153); hypostomal teeth extended beyond anterior margin of ventral wall of hypostoma; median tooth distinctly longer than lateral ones (Fig. 154) or at same level (Fig. 153); lateral serrations well-developed, blunt (except in S. pulverulentum, in which are sharp); hypostomal paralateral teeth present (except in S. brachycladum). Body surface glabrous. Abdomen gradually expanding posteroventrally to last segments, then abruptly contracting to posterior proleg (Fig. 111). Anal sclerite no encircling base of posterior proleg. Posterior portion of abdomen without sclerotized accessory plates. Without 1+1 ventral papillae. Rectal papillae with three multi-branched lobes.

Remarks

Simulium (Hemicnetha) was recovered as monophyletic based on four synapomorphies (Fig. 1, Table 2, node 21), one of them unique: male gonostylus with medial region larger than basal region (20 (0), Figs 60–62). We therefore propose the revalidation of the subgenus, which comprises 19 species.

Coscarón & Coscarón-Árias (2007) divided S. ( Hemicnetha) into four species-groups: Paynei, Brachycladum, Mexicanum, and Oviedoi. We included the following representatives in our analysis: Paynei (five species), Brachycladum (four species), Mexicanum (two species), and Oviedoi (two species). Simulium (Hemicnetha) sensu Coscarón & Coscarón-Árias (2007) was not recovered, because Oviedoi does not group with the remaining species-groups. Moreover, except for Oviedoi, none of the previously defined species-groups in this subgenus were recovered. We therefore revalidate S. ( Hemicnetha), but without Oviedoi and without a subdivision into species-groups pending a more comprehensive investigation on the subgenus.

Distribution

Simulium (Hemicnetha) is mostly distributed in Mesoamerica and South America, being recorded from the following countries: Argentina, Belize, Bolivia, Brazil, Canada, Colombia, Costa Rica, Dominica, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Saint Vincent, Suriname, Trinidad and Tobago and Venezuela. However, S. bricenoi, S. freemani, S. paynei, S. solarii, and S. virgatum are present in the USA, and S. hippovorum occurs in Canada and the USA (Adler 2020).