Belostoma bachmanni De Carlo, 1957

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 : 96-98

Belostoma bachmanni De Carlo

( Figures 2A–C )

Belostoma bachmanni De Carlo, 1957: 52–53 . ( Fig. 2A )

Belostoma bicavum Lauck, 1964: 103 . syn. n. ( Fig. 2B )

Belostoma parvoculum Lauck, 1964: 103–105 . ( Fig. 2C )

Belostoma bachmanni: De Carlo (1966: 107) .

Belostoma bicavum: Nieser (1975: 109) (nec Lauck) [= B. parvoculum ].

Belostoma bachmanni: Schnack (1976: 22) .

Size and shape. Length: male (n=12) = 19.5–20.5 mm, female (n=14) = 19.0–20.0 mm; width: male = 10.0–11.0 mm, female = 9.8–10.4 mm. Body broad.

External morphology. Head: lorogenal cleft with conspicuous fovea ( Fig. 1B ); clypeogenal cleft as long as clypeoloral cleft; anteoculus longer interoculus; eyes globose, as wide as long; interocular space 1.8 to 1.95 times the width of an eye ( Fig. 1C ); vertex with weak mesal carina; article II of labium slightly shorter than article III. Thorax: prosternal keel triangular-shaped, not prominent, projecting forward; pronotum quadrate, without carina; metaxiphus with mesal portion elevated anteriorly and swollen posteriorly, and distal portion concave; membrane of hemelytra reduced, as wide as the maximum width of clavus ( Figs. 2A–C ). Abdomen: pilosity covering less than half of connexivum, constricted between spiracles; pilosity not developed on the VII segment and not covering the sternites.

Male genitalia. Dorsal arms of phallosoma as long as phallobase, wider at the base than at the apex, well developed, meeting at tip of the diverticulum, covering lateral margins of the diverticulum; diverticulum without ventroapical protuberance in lateral and ventral views ( Figs. 3A–C ).

Diagnosis. The prosternal keel triangular, not prominent, projecting forward, and the fovea on lorogenal cleft ( Fig. 1B ) are diagnostic for this species. The wide interocular space and the reduced membrane of the hemelytra are shared with B. triangulum and other species of the genus.

Type material examined. Holotype (♂), allotype (♀), and one adult male and two nymphs paratypes of B. bachmanni pinned ( MACN), PARAGUAY, Concepción department, Puerto Vallemí [San Lázaro municipality], VII.1952, designated by J. A. De Carlo, 1957 ; Paratypes (3 ♂ and 1 ♀) of B. bicavum pinned ( SEMC), BRAZIL, Amazonas state, Purus river, 31.VIII.1935, Ollala, A. coll., designated by D. R. Lauck, 1959 ; Holotype (♂) of B. parvoculum pinned ( SEMC), BRAZIL, Amazonas state, Manacapuru municipality, Solimões river, IV.1926, S. M. Klages coll., designated by D. R. Lauck, 1961 .

Additional material examined. BRAZIL, Amazonas , Novo Airão municipality, Anavilhanas National Park, 01.IX.2001, G. Machado coll., F. Stefanello, 2018 det., 3 ♀ ( INPA) ; São Gabriel da Cachoeira municipality, 07.VIII.2010, R.L. Ferreira-Keppler & S.R.S. Torreias coll., F. Stefanello, 2018 det., 1 ♂ and 2 ♀ ( INPA) ; Barcelos municipality, Aracá river, 00°24’13.8”S 62°55’57.6”W, 25.IX.2014, A.M.O. Pes et al. colls., F. Stefanello, 2018 det., 1 ♂ and 2 ♀ ( INPA) ; Santa Isabel do Rio Negro municipality, Jaradi stream, 00°20’14.2”S 65°12’25.7”W, 18.IX.2014. A.M.O. Pes et al. colls., F. Stefanello, 2018 det., 5 ♂ and 6 ♀ ( INPA) .

Distribution. This species was known only from the type locality. Now, its distribution also comprises part of the Amazon region, specifically in the Purus and Negro river basins, Brazil ( Fig. 4 ). The absence of records from Bolivia and some states in the central and north regions of Brazil is potentially related to undersampling.

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.