Hydaticus xanthomelas ( Brullé, 1837 )

Megna, Yoandri S., Balke, Michael, Apenborn, Rico & Hendrich, Lars, 2019, A review of Peruvian diving beetles of the genus Hydaticus Leach, 1817, with description of Hydaticus (Prodaticus) panguana sp. nov. and notes on other Neotropical species (Coleoptera: Dytiscidae), Zootaxa 4615 (1), pp. 113-130 : 118-122

Hydaticus xanthomelas ( Brullé, 1837)

( Figs. 2D , 7 )

Dytiscus xanthomelas Brullé, 1837: 47 .

Hydaticus xanthomelas ( Brullé, 1837) ; Aubé 1838:181; Trémouilles 1996:18; Benetti & Hamada 2003: 704; Ferreira (Jr.) & Braga 2009: 324; Miller & Bergsten 2014: 74; Miller & Bergsten 2016: 119; Nilsson & Hájek 2019: 97.

Hydaticus rectus Sharp 1882a: 655 ; synonymy by Trémouilles 1996: 18.

Type locality. Argentina, Paraná river , Corrientes .

Material examined. PERU: “Peru, Huánuco Department, Yuyapichis, Panguana Stat. , 2.- 18.10.2009, - 9.616667S, - 74.9333W, Burmeister leg.”, 1 ex., ( ZSM) ; “ Peru, Huánuco Department, Panguana, Yuyapichis river , 25.vii.2013, - 9.616667S, - 74.9333W, at light, R. Apenborn leg.”, 2 exs., ( ZSM) . PARAGUAY: “Paraguay, Dept. Central , Asuncion, 2.X.1992, leg. Drechsel ”, 8 exs., ( CGW) ; “ Paraguay, Dept. Guaira, Garay , 13.-15.X.1992, leg. Drechsel ”, 1 ex., ( CGW) ; “ Paraguay, Chaco Department Hayes, Montelindo , 2.xi.1991, U. Drechsel leg.”, 15 exs., ( CLH, ZSM) ; “ Paraguay, Amanbay P. N., Cerro Cora , 10.ii.1997, Drechsel leg.”, 3 exs. ( CLH) ; “ Paraguay, Chaco Department Hayes, Pozo Colorado , Drechsel leg.”, 2 exs., ( CLH) ; “ Paraguay, Central Department, Capiatá , ii.1995 ”, 5 exs., ( NMW) ; “ Paraguay, Central Department, Cerro Lambaré , 1-xi.1992, Drechsel leg.”, 17 exs., ( NMW) ; “ Paraguay, Guairá Department, Garay , 6-x.1992, Drechsel leg.”, 7 exs., ( NMW) . BRAZIL: “Brasilien, São Paulo, Sammlung A. Zimmermann ”, 1 ex., ( ZSM) ; “ Brasilien, São Paulo, Tiete Floresta , 17.x. 1900, Sammlung A. Zimmermann”, 1 ex., ( ZSM) ; “ Brasilien, Sammlung A. Zimmermann”, 1 ex., ( ZSM) .

Diagnosis. TL= 9.6–10.4 mm; TL-H = 8.9–9.7 mm; MW 4.9–5.4 mm; pronotum testaceous with a black band on the anterior and posterior margin; elytron with basal fasciae not confluent with subbasal, longitudinal and yellowish stripe ( Fig. 2D ); elytron with sublateral and lateral yellow stripes together or separate, forming a lateral and broad longitudinal band. Protarsomere I without a series of spines across the dorsal surface; metatibia with bifid setae parallel to dorsal margin on posterior surface; median lobe of aedeagus with apex rounded in lateral view, and sinuate on preapical dorsal margin ( Fig. 7 ).

Differential diagnosis. Hydaticus xanthomelas is the smallest Neotropical species of the genus, which can easily be used to separate it from the other species with basal fasciae on elytra, such as H. devexus , H. lateralis and H. subfasciatus .

Distribution. Hydaticus xanthomelas has been recorded for Brazil, Bolivia, Paraguay and Argentina ( Trémouilles 1996; Benetti & Hamada 2003; Ferreira (Jr.) & Braga 2009; Miller & Bergsten 2014). Its range of distribution has extended now northwards to Peru.

Ecology. Hydaticus xanthomelas was collected in lowland rivers and smaller streams, rich in submerged and emerged vegetation ( Trémouilles 1996). The two specimens from Panguana were collected at light, not far away from an open cattle farming area near the research station.

Figures

FIGURE 2. Dorsal habitus of H. panguana sp. nov. (A), H. lateralis (B), H. subfasciatus (C) and H. xanthomelas (D). All specimens collected in Panguana, Peru. Scale bar = 5 mm.

FIGURES 4–7. Median lobe of aedeagus in dorsal (A) and lateral view (B): H. panguana sp. nov. (4), H. lateralis (5), H. subfasciatus (6), and H. xanthomelas (7). Scale bar = 1 mm.