Belostoma triangulum Lauck, 1964

Stefanello, Fabiano, Ribeiro, José Ricardo Inacio & Estévez, Ana Lia, 2021, Revision of the Belostoma triangulum group (Insecta: Heteroptera: Belostomatidae), Zootaxa 4958 (1), pp. 95-102 : 99-100

Belostoma triangulum Lauck

( Figure 2D )

Belostoma triangulum Lauck, 1964: 105–107 .

Size and shape. Length: male (n=4) = 19.5–23.0 mm, female (n=4) = 19.5–22.5 mm; width: male = 10.0–12.0 mm, female = 10.5–11.5 mm. Body broad.

External morphology. Head: clypeogenal cleft longer than clypeoloral cleft; anteoculus as long as interoculus; eyes globose, longer than wide; interocular space 1.7 to 1.9 times the width of an eye ( Fig. 1D ); vertex without mesal carina; article II of labium as long as III. Thorax: prosternal keel triangular, prominent, not projecting forward ( Fig. 1A ); pronotum quadrate, without carina; the mesal portion of metaxiphus elevated anteriorly and swollen posteriorly, and distal portion concave; membrane of hemelytra reduced, as wide as the maximum width of clavus ( Fig. 2D ). Abdomen. pilosity covering about half of connexivum, constricted between spiracles; pilosity not developed on segment VII segment and not covering sternites.

Male genitalia. Dorsal arms of phallosoma as long as phallobase, width at the base and apex subequal, welldeveloped, meeting at tip of the diverticulum, covering lateral margins of the diverticulum; diverticulum without ventroapical protuberance in lateral and ventral views ( Figs. 3D–F ).

Diagnosis. The prominent triangular prosternal keel is diagnostic for this species ( Fig. 1A ).

Type material examined. Holotype (♂), allotype (♀) pinned ( SEMC), PERU, Huánuco Department [Pasco Region], Leon Pampa locality, 14.XII.1937, F. Woytkowski coll., designated by D. R. Lauck, 1961 ; Paratype (♂) pinned ( USNM), PERU, Huánuco Department [Region], [Leoncio Prado Province, José Crespo y Castillo District] Aucayacu , designated by D. R. Lauck, 1961 ; Paratypes (2 ♂ and 3 ♀) pinned ( SEMC), PERU, Huánuco department, [Leoncio Prado Province] Shapajilla jungle?, 29.VII.1938, F. Woytkowski coll., designated by D. R. Lauck, 1961 .

Distribution. This species is known only from the type series from Huánuco, Peru, and from a male and a female from Cáceres, Mato Grosso, Brazil (specimens not examined, deposited in the collection of Dr. Arnold S. Menke, University of California, Davis ( Fig. 4 ).

Figures

FIGURE 1. (A) Lateral view of the head of a typical specimen of the Belostoma showing the condition of the prosternal keel and articles of the labium II and III of B. triangulum. (B) Detail of the lorogenal cleft with a conspicuous fovea of B. bachmanni. (C) Dorsal view of the head of B. bachmanni showing the condition of the eyes, anteoculus, and interoculus. (D) Dorsal view of the head of B. triangulum showing with details of the clypeogenal and clypeoloral clefts. ant = anteoculus, int = interoculus, is = interocular space, cgc = clypeogenal cleft, clc = clypeoloral cleft, flg = fovea of lorogenal cleft, pk = prosternal keel, we = width of the eye.

FIGURE 2. Habitus: (A) holotype of Belostoma bachmanni and its labels, (B) paratype of B. bicavum and its labels, (C) holotype of B. parvoculum and its labels, and (D) holotype of B. triangulum and its labels. Scale = 5 mm.

FIGURE 3. (A–C) Dorsal, ventral, and lateral views of phallosoma of Belostoma bachmanni, respectively. (D–F) dorsal, ventral, and lateral views of the phallosoma of Belostoma triangulum, respectively. da = dorsal arms of phallosoma, div = diverticulum of phallosoma, pb = phallobase.

FIGURE 4. Geographic distribution map of the Belostoma triangulum group throughout South America: white dots = B. bachmanni; white squares = B. triangulum.