Simulium (Hearlea) larvispinosum De León

Figs. 1E, 2G–I, 3F, G, 6A–E, 8H, 9G–I.

Simulium (Hearlea) larvispinosum De León, 1948: 5–23, Figs. 1 –19; Dalmat, 1955: 72, 76, 81, 86, 263–268, Figs. 109–111, 229–231, 256, 313, 353, 391, 428; Díaz Nájera & Vulcano, 1962: 93, Figs. 81–84.

Female: Wing length, 3.4 mm. General coloration dark brown. Head blackish, frons brownish silvery pollinose; scutum velvety brown blackish bordered by narrow silver pruinose band, with 1+1 narrow (about 1/4 width of median black stripe) silvery vittae, not reaching to 1+1 anterior subtriangular silvery spots and adjoining posterior silvery prescutellar area. Front sides convergent below; fronto­ocular triangle about as long as wide. Cibarium with thickened, medially concave anterior margin bearing 1+1 short, smooth submedian processes (Fig. 2G). Sc with 8–13 hairs. Mandible with 10+25 serrations. Lacinia with 13–14 retrorse teeth. Claw with sub­basal tooth (Fig. 1E); length/width ratio of hind basitarsus = 4.6–4.7. Sternite VIII with 14–16 hairs per side; genital fork and spermatheca as in Figures 2H–I, respectively; cercus subrectangular; anal lobe with longitudinal fold, and thickly haired distally.

Male: Wing length, 3.4 mm. Scutum velvety black, bordered by silvery pruinosity as are the humeral angles. Scutellum black. Abdomen blackish. Sc bare. Hind basitarsus 3.5– 3.6 times longer than broad. Basistylus subquadrate, 1/2 of dististylus length; dististylus with abundant pilosity mediobasally, and subterminal accuminate spine (Fig. 3F). Endoparameres with strong hooks; median sclerite wide basally; ventral plate subovoidal, without evident median carina (Fig. 3G).

Pupa: Length: basal, 3.4 mm. Cocoon slipper shaped, compactly woven (threads not evident); anterior margin slightly reinforced. Frontoclypeus protruded basally, without platelets but with impression of minute, very abundant granules; 1+1 facial and 2+2 frontal single, stout trichomes; thorax with sparse, small, accuminate platelets posteriorly and impression of platelets on remainder of integument and 5 stout, single, spine­like trichomes per side. Gill rigid, granulose, cylindrical shaped, with two primary branches: dorsal branch smallest, reduced to accuminate, digitiform process; medial branch largest, directed anterodorsally and somewhat medially, with one large somewhat inflated main branch having 3 groups of short, stout, accuminate subbasal accessory branches; two most prominent subbasal branches directed anterolaterally and anteromedially, the former bifurcate and latter trifurcate; least prominent accessory branch directed anterolaterally, distally subdivided (Figs. 6A–E); ventral branch small, curved, directed anteromedially; all gill branches, other than large inflated branch of median trunk, with spinulate, sclerotized apices. Abdominal tergite X with/without terminal spines.

Larva: Length, 8 mm. Color yellowish to light brown (in alcohol). General aspect as Fig. 9G. Cephalic apotome without discernible headspots, homogeneous except for narrow darkened basal stripe; cervical sclerites elongated, adjoining basal margin of apotome; ratio hypostoma/hypostomal bridge = 1.2–1.5. Labral fan with 43–48 primary rays. Hypostoma with median tooth stout, surpassing height of other teeth; corner teeth shorter than intermediate teeth; 12–17 lateral setae per side, without discal setae, and with few lateral serrations. Postgenal cleft dome shaped, with deep, anteromedian incision (Fig. 8H). Antenna surpassing apex of labral fan stalk. Ratio of antennal articles = 1:1.4–1.5:0.9 (proximal: medial: distal). Mandible with 4–5 internal teeth; 2 marginal teeth, second tooth 1/2 length of anterior tooth. Lateral sclerite of thoracic proleg with 45–50 teeth. Anal sclerite with ventral struts encircling posterior circlet. Accessory plates in the form of 2+2 apical, subconical, heavily sclerotized dorsolateral plates (Figs. 9H–I, [dd]), 1+1 ventrolateral, subconical, subannulate, plates with indentations along external border (Fig. 9I [vl]), and 1+1 dorsolateral, subrectangular, flattened plates anterior to rectal papillae (Figs. 9H– I [df]). Segment VIII lacking ventrolateral papillae. Posterior circlet with ca. 152 rows of 23–26 hooks. Rectal papillae trilobed, with 6–8 lobules per lobe (18–24 total).

Material examined: Guatemala: (Dalmat collection USNM), Chimaltenango, Acatenango, Río Monjón, Fca. Sta. Margarita, 1 female, 8 March 1948; río La Torre, Fca. La Torre, 1 female, 17 August 1948; Finca Barretal, camino a San Vicente Pacapli, 8 pupae, 1 larva, 18 April 1945; Sololá, Atitlan, río Catarata, Sta. Alicia, 5 females, 1 male, abundant larvae, 24 March 1951, H. Dalmat; same locality, abundant larvae, 22 February 1945; (AMNH), same locality, abundant larvae, 22 February 1945, (AMNH); Río Santa Anita, Finca Monte de Oro, 950 m: 67 pupae, abundant eggs (AMNH). Seven vials of Guatemalan material from AMNH lacked locality information have only an internal collection number of XXII. Seven such vials included the following specimens: 60 larvae, 36 pupae; 25 larvae, 16 pupae; 36 larvae, 5 pupae; 26 larvae, 5 pupae; 36 larvae; 48 larvae, 56 larvae; 77 larvae.

Distribution: Guatemala: Chimaltenango, Sololá, Suchitepequez; México: Chiapas.

Discussion: Simulium (Hearlea) johnsoni Vargas & Díaz Nájera is very similar to S. larvispinosum, but the pupal gills of these two species exhibit slight differences as was explained in that species. Adults of S. carolinae do not differ superficially. The closest species based upon the pupa gill is S. gorirossiae, but these species exhibit differences in the larval accessory plates, with the ventrolateral plate more subquadrate and having long, accuminated projections and the dorsolateral flattened plates being positioned diagonally at sides of rectal papillae in S. gorirossiae . Simulium gorirossiae also differs in that it has sclerotized ventrolateral papillae on eighth sternite.