Belostomatidae, Leach, 1815

Franco, Cleilton Lima, Stefanello, Fabiano, Azevêdo, Carlos Augusto Silva de & Moreira, Felipe Ferraz Figueiredo, 2024, Belostomatidae Leach, 1815 (Insecta: Hemiptera: Heteroptera: Nepomorpha) of northeastern Brazil, European Journal of Taxonomy 932, pp. 271-304 : 294-295

Key to the species of Belostomatidae from northeastern Brazil

The key includes characters previously used to recognized species of Lethocerus from Perez-Goodwyn (2006) and Belostoma from Lauck (1964), Estévez & Polhemus (2007), Ribeiro (2007), Ribeiro & Alecrim (2008), Ribeiro et al. (2017), and Stefanello et al. (2021).

1. Sternites IV–VI subdivided laterally by a suture-like fold ( Perez-Goodwyn 2006: figs 30–31); labium short, with second article thicker than long.....................................2 Lethocerus Mayr, 1853

– Sternites IV–VI not subdivided; labium long, with second article longer than thick (Stefanello et al. 2021: fig. 1A)...........................................................................................4 Belostoma Latreille, 1807

2. Ventromesal projection of hind tibia pointed ( Perez-Goodwyn 2006: fig. 4); body length 90 mm or more ......................................................................................... Lethocerus maximus De Carlo, 1938

– Ventromesal projection of hind tibia rounded ( Perez-Goodwyn 2006: fig. 3); body length less than 70 mm ................................................................................................................................................ 3

3. Parasternites III–VII with longitudinal dark stripe ( Fig. 14 ); prosternal keel pointed at the apex ( Perez-Goodwyn 2006: fig. 38) .............................................. L. annulipes (Herrich-Schäffer, 1845)

– Parasternites III–VII without longitudinal dark stripe; prosternal keel rounded at the apex ( Perez-Goodwyn 2006: fig. 37).......................................................................... L. delpontei De Carlo, 1930

4. Eye triangular, lateral margins straight or slightly rounded (Stefanello 2021: fig. 1C–D)................ 5

– Eye globose, lateral margins rounded................................................................................................ 9

5. Anteoculus longer than interoculus; body length 40–52 mm ............................................................ 6

– Anteoculus as long as interoculus (Stefanello 2021: fig. 1C); body length 21–28 mm .................... 7

6. Ventral abdominal pilosity covering entirety of connexivum ( Fig. 7 )................................................. .................................................................................................. Belostoma dilatatum ( Dufour, 1863)

– Ventral abdominal pilosity covering only half of connexivum ( Fig. 8 ) .............................................. ................................................................................................................ B. gestroi Montandon, 1900

7. Ventral abdominal pilosity covering entirety of connexivum and part of sternites ( Ribeiro 2007: fig. 2E) .................................................................................................. B. costalimai De Carlo, 1938

– Ventral abdominal pilosity not covering entirety of connexivum and not covering sternites (e.g., Figs 3, 5 and Ribeiro 2007: fig. 2A) .................................................................................................. 8

8. Metaxiphus with a carina-like structure developed along mesal part; lateral folding of the pronotum broad, extending up to the posterior part ....................................................... B. bosqi De Carlo, 1932

– Metaxiphus with proximal part elevated and distal part swollen; lateral folding of the pronotum narrow, not extending up to the posterior part................................... B. discretum Montandon, 1903

9. Vertex, pronotum, and posterior part of scutellum with distinct carina; vertex straight below the ocular line; eye small, interocular space> 1.7× eye width ............................................................. 10

– Vertex, pronotum, and posterior part of scutellum without distinct carina; vertex prominent above the ocular line; eye large, interocular space <1.6× eye width .........................................................11

10. Body narrow, ratio length/width about 2.3×; lateral margins of body almost parallel; length of anteoculus 0.88–1.13 × length of interoculus ........................... B. aurivillianum ( Montandon, 1899)

– Body broad, ratio length/width about 2.0×; lateral margins of body slightly convex; length of anteoculus 1.15–1.59 × length of interoculus .............................. B. stollii ( Amyot & Serville, 1843)

11. Body 10–20 mm in length; prosternal keel not elevated ( Ribeiro 2007: fig. 12A–B); anteoculus shorter than interoculus.................................................................................................................... 12

– Body 28–52 mm in length; prosternal keel prominent, with apex rounded ( Ribeiro 2007: fig. 7A–C); anteoculus longer than interoculus .................................................................................................. 16

12. Ventral diverticulum straight distally, in lateral view ( Ribeiro 2007: fig. 11G–I); diverticulum broad ................................................................................................................................................ 13

– Ventral diverticulum curved downward, in lateral view (as in Figs 35, 37 ); diverticulum elliptical .. ......................................................................................................................................................... 14

13. Body 13–16 mm in length; ratio length/width about 2.35, narrow species; dorsal arms of phallosoma straight, covering lateral margins of diverticulum............ B. amazonum Estévez & Polhemus, 2001

– Body 17–19 mm in length, ratio length/width about 2.15, elliptical species; dorsal arms of phallosoma slightly convergent, not covering lateral margins of diverticulum ...... B. horvathi Montandon, 1903

14. Body more than 13 mm in length; prosternal keel prominent...................... B. plebejum ( Stål, 1860)

– Body 10.5–13 mm in length; prosternal keel not prominent........................................................... 15

15. Diverticulum of phallosoma with strong, median dorsal depression, dorsal arms of phallosoma divergent ( Ribeiro 2007: fig. 12C–E) ...................................................... B. micantulum ( Stål, 1860)

– Diverticulum of phallosoma with slight, median dorsal depression, dorsal arms of phallosoma abruptly convergent ( Ribeiro & Alecrim 2008: fig. 4) ......... B. nessimiani Ribeiro & Alecrim, 2008

16. Body narrow, elongate; diverticulum of phallosoma with lateral margins sinuous, broader basally than apically ( Ribeiro et al. 2017: figs 32, 52) ................................................................................ 17

– Body elliptical; diverticulum of phallosoma evenly elliptical......................................................... 18

17. Ratio basal/apical width of ventral diverticulum about 2.3× (ventral view), dorsal arms divergent ( Figs 32–33 )...................................................................................... B. elongatum Montandon, 1908

– Ratio basal/apical width of ventral diverticulum about 2.0 × (ventral view), dorsal arms more parallel .................................................................................................... B. foveolatum ( Mayr, 1863)

18. Clypeogenal cleft longer than clypeoloral cleft............................................... B. harrisi Lauck, 1964

– Clypeogenal cleft as long as clypeoloral cleft (Stefanello et al. 2021: fig. 1D).............................. 19

19. Prosternal keel narrowly rounded to acute ( Fig. 24 ); dorsal arms of phallosoma broad ( Fig. 30 ) ( Ribeiro et al. 2017: figs 39–43); body length about 42–50 mm ............... B. dentatum ( Mayr, 1863)

– Prosternal keel rounded; dorsal arms moderately slender; body length about 29–35 mm .............. 20

20. Ventral diverticulum of phallosoma twice as wide as long (ventral view), ventroapical protuberance poorly developed ( Fig. 29 ) ........................................................ B. anurum ( Herrich-Schäffer, 1848)

– Ventral diverticulum of phallosoma 1.3× as wide as long (ventral view); ventroapical protuberance well developed............................................................................................ B. dallasi De Carlo, 1930

Figures

Figs 9–16. Dorsal and ventral habitus of examined species of Belostomatidae. 9. Belostoma discretum Montandon, 1903, ♂, Carolina municipality. 10. B. micantulum (Stål, 1860), ♂, Caxias municipality. 11. B. nessimiani Ribeiro & Alecrim, 2008, ♂, Caxias municipality. 12. B. aurivillianum (Montandon, 1899), ♂, Cândido Mendes municipality. 13. B. stollii (Amyot & Serville, 1843), ♀, Cândido Mendes municipality. 14. Lethocerus annulipes (Herrich-Schäffer, 1845), ♂, Ubajara municipality. 15. L. delpontei De Carlo, 1930, ♂, Caxias municipality. 16. L. maximus De Carlo, 1938, ♀, Riachão municipality. Scale bars: 9–11, 14–16 = 10 mm; 12–13 = 1 mm.

Figs 1–8. Dorsal and ventral habitus of males of examined species of Belostomatidae. 1. Belostoma bosqi De Carlo, 1932, ♂, Carolina municipality. 2. B. costalimai De Carlo, 1938, ♀, Caxias municipality. 3. B. anurum (Herrich-Schäffer, 1848), ♀, Caracol municipality. 4. B. dentatum (Mayr, 1863), ♀, Carolina municipality. 5. B. elongatum Montandon, 1908, ♀, Cândido Mendes municipality. 6. B. harrisi Lauck, 1964, ♀, Carolina municipality. 7. B. dilatatum (Dufour, 1863), ♂, Carolina municipality. 8. B. gestroi Montandon, 1900, ♂, Carolina municipality. Scale bars: 10 mm.

Figs 28–37. Male genitalia of species of Belostoma: phallosoma (phallotheca, dorsal arms, and diverticulum). 28–29. Belostoma anurum (Herrich-Schäffer, 1848). 28. Dorsal and ventral view. 29. Lateral view. 30–31. B. dentatum (Mayr, 1863). 30. Dorsal and ventral view. 31. Lateral view. 32–33. B. elongatum Montandon, 1908. 32. Dorsal and ventral view. 33. Lateral view. 34– 35. B. micantulum (Stål, 1860). 34. Dorsal and ventral view. 35. Lateral view. 36–37. B. nessimiani Ribeiro & Alecrim, 2008. 36. Dorsal and ventral view. 37. Lateral view. Scale bars: 28–29 = 1 mm; 30–33 = 0.5 mm; 34–37 = 0.2 mm.

Figs 23–27. Lateral view of the head, pronotum and prosternal keel of examined species of Belostomatidae. 23. Belostoma anurum (Herrich-Schäffer, 1848). 24. B. dentatum (Mayr, 1863). 25. B. elongatum Montandon, 1908. 26. B. micantulum (Stål, 1860). 27. B. nessimiani Ribeiro & Alecrim, 2008. Scale bars: 1 mm.