Hamadiana chapadensis, 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 : 177-179

Hamadiana chapadensis sp. n.

( Figs 1–15 )

urn:lsid:zoobank.org:act:88532963-8F7F-412B-A7BB-33CE812276BC

Type locality. Brazil: Goiás State, Alto Paraíso de Goiás County, “Rio dos Couros, Cachoeira” (ca. 14°17’S 047°45’W) .

Holotype. m*, “ Brasil, Goiás, Alto Paraíso de Goiás, Rio dos Couros, cachoeira, 21.vi.2017, leg. N. Hamada et al.”, “ Holotype, Hamadiana gen. n., chapadensis sp. n. Benetti, Short & Michat det. 2019” [red, printed] ( INPA).

Description. Habitus ( Figs 1–2 ). Body shape oval, short and broad, gradually narrowed posteriorly, with apex slightly acuminate; lateral outline continuously curved from head to elytra; dorsally strongly convex, ventrally slightly convex. Maximum width at about mid length.

Measurements (n = 1). TL: 3.1 mm; TL-H: 2.85 mm; MW: 1.9 mm; EL: 2.35 mm; HW: 1.2 mm; PW: 1.7 mm; EW: 0.75 mm; TL/MW: 1.63; HW/EW: 1.61.

Color ( Figs 1, 2 ). Head orangish; pronotum brown with two broad dark yellow to orangish spots on lateral margins and one vague light spot on middle region; elytra brown, each with four well marked yellow spots (one basal, one submedian reaching lateral margin, one submedian near suture and one subapical) and two vague light spots on apical third (one elongate near suture and one on apex); prosternum, procoxae and basal 1/3 of epipleura dark yellow; metaventrite, metacoxae, abdominal ventrites and apical 3/4 of epipleura brown to reddish-brown (ventrite 1 and posterior margins of ventrites 3–5 somewhat lighter); legs reddish-brown.

Head. Surface smooth, shiny, without microreticulation, with fine impressed shallow punctures near anterior and inner margin of eyes.

Pronotum. Surface smooth, shiny, with fine microreticulation composed of polygonal cells; with fine regular micropunctation and well impressed wide punctures mostly along lateral sides and fore margin, arranged in more or less regular series. Basal margin nearly straight, lateral margins bordered, posterior angles rounded ( Fig. 3 ).

Elytra. Surface smooth, shiny, with fine microreticulation composed of polygonal cells; with fine, regular, shallow micropunctation and faintly impressed, hardly visible wide punctures, sparse and arranged in irregular, longitudinal series, mainly on apical third. Epipleuron without microreticulation, with some sparse punctures at middle. Scutellum not visible when elytra closed ( Fig. 1 ). Elytra elongate, apically slightly acuminate, attenuate and narrowly bordered laterally; suture between elytron and epipleuron faintly visible dorsally on apical third; epipleuron broad up to level of hind margin of metacoxal plates, then strongly narrowed, distinctly attenuate just before elytral tip ( Fig. 2 ).

Underside. Surface smooth, shiny; microreticulation present on metacoxal processes and abdominal ventrites, composed of elongate cells; metaventrite with several punctures in middle region; metacoxa with stridulatory file in form of a series of parallel, closely spaced ridges ( Fig. 5 ); last abdominal ventrite with shallow scratchlike microsculpture on posterior half ( Fig. 10 ). Prosternum and head separated by a shallow step; prosternum with small median ridge. Prosternal process elongate, lanceolate and bordered, clearly carinate, reaching mesocoxae but not extending beyond their hind margins; laterally compressed at level of procoxae, apically simple, with apex elongate, thornlike, very acute ( Figs 4 , 8 ). Metasternal wings thin and arched; metacoxal lines converging anteriad in posterior 3/4 of their length, slightly diverging anteriad in anterior 1/4 ( Figs 5 , 9 ). Metacoxal process distally bilobed, with hind margin deeply incised and medially slightly protruded backwards ( Figs 5 , 9 ). Ventrite 3 with a medial protrusion on posterior margin (= median process raised apically) ( Fig. 6 ) being probably a male sexual character; last abdominal ventrite as long as previous two ventrites combined, almost straight at sides, with anterolateral angles rounded and hind margin indented ( Fig. 10 ).

Legs. Fore and middle legs long and slender; tarsomeres longer than wide, tarsomere 5 almost as long as tarsomeres 3 and 4 combined; pro- and mesotarsal claws slightly shorter than tarsomere 5; protarsal claws subequal in length and shape, unmodified; mesotibial spurs short, larger one not longer than first two tarsomeres together; posterior surface of mesofemora with a series of 3–4 long, stiff setae; swimming setae on mesotibiae present only apically. Metatibiae short, broad, about 2/3 as long as metafemur, with two simple apical spurs being acuminate at tip ( Fig. 6 ); metatarsomeres 1–4 with well developed, elongate lobes on posterolateral angles, each lobe bearing small set of flat spines and a strong spine on inner margin ( Fig. 7 ); metatarsomere 5 bilobed, inner lobe long and acute, outer lobe about half shorter, bearing single, short, curved, apically rounded claw; claw about as long as outer lobe of metatarsomere ( Fig. 11 ).

Male. Pro- and mesotarsomeres 1–3 not dilated, each one bearing ventrally a pair of stalked suction palettes ( Fig. 2 ). Aedeagus asymmetrical as in other genera of Laccophilini . Median lobe in dorsal view ( Fig. 12 ) with lateral margins slightly curved, basal 1/2 broader, distal 1/2 narrower, tip slightly curved; in lateral view ( Fig. 13 ) elongate, with curved thicker base, distal portion subparallel at basal 2/3, narrowed towards apex at distal 1/3, ending in curved rounded apex; ventral margin sinuous, dorsal margin straight in middle region, with small protrusion at distal 1/4 near apex. Parameres short, right one larger, both reaching less than half of length of median lobe. Left paramere ( Fig. 14 ) in lateral view with ventral margin almost straight and dorsal margin convex; with small pointed apex and two long setae at tip. Right paramere ( Fig. 15 ) in lateral view subtriangular, wider at base, ventral margin almost straight, dorsal margin slightly sinuous; lacking setae at tip.

Female. Unknown.

Etymology. This species is named after the “Chapada dos Veadeiros”, a plateau in northeast of the Goiás state, Central Brazil, where the type locality is located. The name is an adjective in the nominative singular.

Distribution and ecology. Central Brazil, currently only known from the state of Goiás ( Fig. 16 ). The specimen was collected in a river, in rapids ( Fig. 17 ) at 950 m a.s.l., in the tropical savanna biome “cerrado”.

Figures

FIGURE 16. Type locality of Hamadiana chapadensis sp. n.

FIGURE 17. Habitat of Hamadiana chapadensis sp. n. Brazil: Goiás State, Alto Paraíso de Goiás County, “Rio dos Couros”.

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.