Hamadiana, Benetti & Short & Michat, 2019

Benetti, Cesar J., Short, Andrew E. Z. & Michat, Mariano C., 2019, Hamadiana chapadensis, a new genus and species of diving beetle from Brazil (Coleoptera, Dytiscidae, Laccophilinae, Laccophilini), Zootaxa 4615 (1), pp. 176-184 : 177

Hamadiana gen. n.

( Figs 1–15 )

urn:lsid:zoobank.org:act:15244304-1BD6-4054-B414-CB8216E4F5C7

Type species. Hamadiana chapadensis sp. n. by present designation.

Description. The new genus is unique among Laccophilini in having the hind margin of metacoxal process deeply incised and medially slightly protruded backwards ( Fig. 9 ). Other diagnostic characters are: antennomeres simple, not expanded; metacoxal lines not straight, converging anteriad in posterior 3/4 of their length, slightly diverging anteriad in anterior 1/4 ( Fig. 9 ); metatibia with two simple apical spurs ( Fig. 6 ). Moreover, the last metatarsomere is bilobed, with inner lobe long and acute and outer lobe about half shorter; the single metatarsal claw is curved, apically rounded and short, about as long as the outer lobe of last metatarsomere ( Fig. 11 ).

Etymology. This genus is named after Neusa Hamada, INPA, in recognition of her significant contribution to the knowledge of aquatic insects in Amazonia. The gender of the name is feminine.

Discussion. Among the Neotropical genera of Laccophilini , the new genus is easily differentiated from Laccophilus and Napodytes in having two simple apical spurs on metatibiae (single apical spur in Napodytes and two apically bifid spurs in Laccophilus ). This character is shared with Laccodytes and Laccomimus , but Hamadiana gen. n. can be differentiated from these two genera by the shape of metacoxal processes, which are unique in having the hind margin strongly incised and medially protruded backwards ( Fig. 9 ). From Laccodytes , the new genus can be distinguished by the metacoxal lines converging anteriad in posterior 3/4 of their length, slightly diverging anteriad in anterior 1/4 (straight in Laccodytes ) and by the larger body (more than 3 mm in length in Hamadiana gen. n. and less than 2.4 mm in Laccodytes ). From Laccomimus , Hamadiana gen. n. differs also in having the prosternal process elongate and apically acute (relatively short and apically rounded in Laccomimus ), in the mesotibial spurs not longer than mesotarsomeres 1–2 (longer than mesotarsomeres 1–4 in Laccomimus ) and in the larger body (more than 3 mm in length in Hamadiana gen. n. and less than 2.5 mm in Laccomimus ).

Figures

FIGURES 1–2. Hamadiana chapadensis sp. n.: 1) habitus, dorsal view; 2) habitus, ventral view.

FIGURES 3–7. Hamadiana chapadensis sp. n.: 3) posterior pronotal angle; 4) prosternal process; 5) metacoxa, arrow indicating stridulatory file; 6) abdomen and right hind-leg, arrows indicating simple apical tibial spurs and medial marginal protrusion on abdominal ventrite 3; 7) left metatarsus.

FIGURE 8–11. Hamadiana chapadensis sp. n., ventral view: 8) prosternal process; 9) metacoxal processes; 10) last abdominal ventrite; 11) left metatarsus.

FIGURES 12–15. Hamadiana chapadensis sp. n.: 12) median lobe, dorsal view; 13) median lobe, left lateral view; 14) left paramere, left lateral view; 15) right paramere, left lateral view.