Simulium (Hearlea) gorirossiae Vargas & Diaz Najera

Simulium (Hearlea) gorirossiae Vargas & Díaz Nájera

Figs. 1D, 6F, G, 8D–G, 9D–F.

Simulium (Hearlea) gorirossii Vargas & Díaz Nájera, 1957: 199–202, Figs. 143–151; Díaz Nájera & Vulcano, 1962: 92: Figs. 67–71.

Female: Wing length, 3.2 mm. Coloration blackish. Head dark brown, with frons and clypeus silvery pollinose. Scutum velvety black with 1+1 silvery vittae adjoined with submedian anterior subtriangular silvery spots; laterally bordered by narrow whitish gray pruinose band adjoining whitish prescutellar area. Abdomen blackish. Fronto­ocular triangle about as long as wide; cibarium with basal portion as in S. larvispinosum, with hyaline internal margin and 1+1 small rounded submedian processes. Sc bare. Genitalia typical for subgenus, with cercus rectangular, flattened distally, anal lobe with a transversal tegumentary fold and very haired apically; gonapophysis subtriangular, with blunt apex similar to that of S. larvispinosum.

Male: Wing length, 3.0 mm. Scutum velvety black with anterior 1/3 pruinose, continued by narrow band bordering laterally and meeting with whitish gray pruinose prescutellar area. Abdomen blackish. Sc bare. Genitalia similar to those of S. larvispinosum, except ventral plate more elevated medially.

Pupa: Length: basal, 2.4–2.7 mm; dorsal, 1.5–1.7 mm. Cocoon slipper shaped, open anteriorly, thickly woven, with narrow, ragged rim along anterior margin. Clypeus and thoracic dorsum with few to abundant, small, accuminate platelets and simple, stout, trichomes. Gill similar to that of S. larvispinosum, but with large apical lobe of medial branch narrower and dorsal branch more elongate, basally sclerotized, and apically curved; in dorsal view, submedial accuminate branches of major (medial) branch splayed laterally (Figs. 6F, G). Abdominal tergite X lacking terminal spines.

Larva: Length, 6.5–7.0 mm. General coloration light yellowish gray. Cephalic apotome uniformly colored, slightly darkened basally (Fig. 8D). Labral fan with 50–52 primary rays. Antenna longer than stalk of labral fan; ratio of antennal articles = 1:1.4:0.7 (proximal: medial: distal); medial article pseudosegmented (Figure 8E). Mandible with outer margin strong curved (Fig. 8F); internal teeth arrangeded in two rows of 4 teeth, with first and second teeth very curved, 2 marginal teeth, and one robust and long lateral tooth, 1/3 of which surpasses inner margin of mandible (Fig. 8G). Hypostoma with anterior margin as in S. larvispinosum, with prominent median tooth and intermediate teeth longer than corner teeth; 14–21 lateral setae per side. Postgenal cleft deep, without anterior accuminate incision; ratio of hypostoma/hypostomal bridge = 0.9–1.1. Ratio of antennal articles = 1:1.3–1.6:0.9 (proximal: medial: distal). Prothoracic proleg lateral sclerite comb with 47– 55 teeth. Abdominal segment VIII with 1+1 ventrolateral, apically sclerotized papillae (Figs. 9D, F [vp]). Anal sclerite with ventral struts projected distally encircling posterior circlet, bordered laterally by heavily sclerotized, spinous accessory plates composed of the following: 2+2 conical dorsolateral projections [dd]; 1+1 flattened, expanded, ventrolateral plates with accuminate projections (Fig. 9D [vl]), abundant accuminate tubercles, and sparse minute trichomes; and 1+1 dorsolateral, irregularly bordered, elongate plates positioned diagonally to lateral lobes of rectal papillae (Figs. 9E [df]). Posterior circlet with 272–282 rows of 30–35 hooks. Rectal papillae trilobed, with 6–10 lobules per lobe (18–30 total).

Material examined: Mexico: Paratypes Chiapas, Mariscal, 1 female, 1 male, III­1946, col. A. Díaz Nájera (INDRE). Guatemala: Sololá, Atitlán, río Catarata, Sta. Alicia, Fca. Monte de Oro, several larvae and 1 pupa, 24 March 1951 (USNM); río Santa Anita, Fca. Monte de Oro, abundant larvae, 22 February 1945 (AMNH); XXII, without locality 32 larvae, 3 pupae; another lot: 6 pupae; another lot: 10 larvae, (AMNH).

Distribution: México, Chiapas and Veracruz; Guatemala, Sololá.

Discussion: Simulium (Hearlea) gorirossiae, S. larvispinosum, S. menchacai, S. carolinae, S. johnson, and S. temascalense are very similar but can be distinguished by subtle differences in the pupal gill and accessory plates of the larval anal sclerite.