Belostoma, Latreille, 1807

Stefanello, Fabiano, 2021, The new Belostoma fittkaui species group with supplemental descriptions of B fittkaui De Carlo and B. sayagoi De Carlo, Zootaxa 4942 (4), pp. 583-591 : 587

Key for Belostoma species groups

The key includes some characters previously used to recognized species groups following Estévez & Polhemus (2001) and Ribeiro (2007), in combination with new characters based mainly on the head, pronotum and hindwing, making it also possible to identify females. Nevertheless, for small-sized species groups, in many cases, it is impossible to recognize the species groups without male genitalic information. Belostoma aurivillianum (Montandon, 1899) and B. stollii (Amyot & Serville, 1843) were previously treated in separate groups, but share some unique features, such as the carinas on the vertex, pronotum and posterior part of the scutellum, in addition to the vertex being straight below the ocular line. For this reason, B. aurivillianum is treated here as a member of the stollii group.

1a. Eyes triangular, lateral margins straight or slightly rounded.................................................... 2

1b. Eyes globose, lateral margins rounded..................................................................... 5

2a. Article II of labium shorter than III, about 0.70×; pilosity covering entirety of the sterna and connexivum.......... fittkaui

2b. Article II of labium subequal in length to III................................................................ 3

3a. Anteoculus longer than interoculus; body ± 35 mm in length; pilosity covering entirety of the connexivum, except in B. gestroi ......................................................................................... dilatatum

3b. Anteoculus as long as than interoculus; body 22–28 mm in length; pubescence not covering entirety of the connexivum, except in B. costalimai ....................................................................................... 4

4a. Pronotum trapezoidal with lateral fold extending to the posterior part......................................... bergi

4b. Pronotum quadrate with lateral fold not extending to the posterior part.................................... discretum

5a. Pubescence covering entirety of the connexivum............................................................ 6

5b. Pubescence not covering entirety of the connexivum......................................................... 8

6a. Pubescence covering part of the abdominal sterna............................................... testaceopallidum

6b. Pubescence absent from abdominal sterna, except in B. noualhieri .............................................. 7

7a. Mp vein of the hindwing absent, South American species............................................ bifoveolatum

7b. Mp vein of the hindwing present, North American species............................................. flumineum

8a. Vertex, pronotum, and posterior part of scutellum with distinct median longitudinal carina; vertex straight below the ocular line............................................................................................. stollii

8b. Vertex, pronotum, and posterior part of scutellum without distinct median longitudinal carina; vertex prominent above the ocular line........................................................................................... 9

9a. Prosternal keel triangular; 19–23 mm in length, broad species.......................................... triangulum

9b. Prosternal keel rounded, species variable in size and shape................................................... 10

10a. Body 28–52 mm in length; prosternal keel elevated with apex rounded; diverticulum of male genitalia with a conspicuous ventral protuberance............................................................................ dentatum

10b. Body 9–24 mm in length; prosternal keel not elevated; diverticulum without ventral protuberance.................... 11

11a. Dorsal arms of phallosoma narrowed, with diverticulum broadened (see Fig. 11 in Ribeiro 2009)..................... 12

11b. Dorsal arms of phallosoma not narrowed, diverticulum not broadened.......................................... 13

12a. Pubescence covering more than half of the connexivum area............................................. oxyurum

12b. Pubescence covering less than half of the connexivum area............................................. denticolle

13a. Prosternal keel with rounded, but not elevated apex; phallosoma strongly curved downward; 9–16 mm in length; South American species (see Fig. 12 from Ribeiro 2009).......................................................... plebejum

13b. Prosternal keel with rounded and elevated apex; phallosoma straight not curved; 15–21 mm in length, North American species............................................................................................ minor