Gyrinus (Oreogyrinus) rhyssonotum, 2019

Colpani, Daniara, Benetti, Cesar João & Hamada, Neusa, 2019, Gyrinus rhyssonotum sp. n., a new species of Gyrinidae (Coleoptera: Adephaga) from northern Brazil, Zootaxa 4560 (1), pp. 164-170 : 165-168

Gyrinus (Oreogyrinus) rhyssonotum sp. n.

( Figs 1 A–E, 2A–B, 3A–C)

Type locality. BRAZIL, Amazonas state, Barcelos County, Serra do Aracá, 00°54'03.89"N 63°25'45.30"W ( Figs 3 A–C) .

Type material. Holotype ♂ (INPA, pinned) “ BRAZIL, Amazonas State , Barcelos County, Serra do Aracá, first-order stream, 00°54'03.89"N 63°25'45.30"W, 1104 m, 27.VII.2009, leg. Pes, A.M.O. &. Hamada, N.”. Paratypes (29 exs): 2 ♂, 8 ♀ (1 ♂, 7 ♀ INPA, pinned; 1 ♂, 1 ♀ ZSM, pinned), same locality as holotype; 2 ♂ ( INPA, pinned), same locality except “pond near Igarapé da Anta , 30.VII.09, leg. Pes, A.M.O. &. Hamada, N.”; 10 ♂, 7 ♀ ( INPA, alcohol) same data except “stream, Igarapé da Anta, 00°54'30.38"N 63°26'24.32"W, 116 m, 01.VIII.09, leg. Pes, A.M.O. &. Hamada, N.” .

Diagnosis. Pronotal and elytral margins broad ( Fig. 1A ); elytral disc lacking reticulation, appearing polished; elytral striae VII–IX sulcate, striae I–XI with mostly distinct round punctures in longitudinal series; elytral apex round to slightly truncate ( Fig. 1A ); epipleural angle indistinct; median lobe of aedeagus shorter than parameres, broad, with apex broadened and almost truncate, base 1.4 times broader than apex ( Fig. 2A ); parameres broad with apex truncate, with slightly prominent internal angle; gonocoxae elongate, with apices truncate ( Fig. 2B ).

Description. Male. Habitus. Medium-sized species. Body oval, broad, weakly convex in lateral view, greatest convexity near elytral mid-length, evenly depressed anteriorly and posteriorly ( Fig. 1A ).

Measurements (n = 20). TL: 4.44–4.95 mm; MW: 2.53–2.80 mm; HL: 0.74–0.95 mm; HW: 1.52–1.73 mm; CL: 0.12–0.17 mm; CW: 0.66–0.76 mm; DD: 0.50–0.59 mm; LW: 0.45–0.63 mm; PL: 0.75–0.81 mm; EL: 3.23– 3.72 mm; EH: 1.25–1.67 mm; EW: 1.23–2.80 mm; PTL: 0.80–0.96 mm; PFL: 1.07–1.21 mm; PFW: 0.29–0.33 mm; PTAL: 0.45–0.50 mm; PTAW: 0.15–0.19 mm.

Coloration ( Figs. 1 A–C). Head, pronotum and elytra black, with blue metallic reflections ( Fig. 1A, B ); lateral margins of pronotum and elytra (striae VIII–XI) with reflections bronzy yellow and green. Ventral view dark brown, with bronzy metallic reflections; labial palpomeres and last maxillary palpomere with dark-brown apices; meso and metacoxae darker with orangish-yellow pitches apically; abdominal ventrites VII and VIII reddish brown to dark orange yellow; legs dark yellow to orangish-yellow with dark spots.

Sculpture and structure (at a magnification of 120×). Head. 2.0 times wider than long ( Fig. 1B ); front with two round depressions; frontolateral margins convex, reticulation evident, composed of scale-like sculpticells; vertex and frons with striae evident and sparse punctures separated by 2– 4X diameter of a puncture, frontolateral and postocular margins wrinkled ( Fig. 1B ); clypeus 1.2 times longer than labrum, with anterior edge nearly straight, frontoclypeal suture with posterior margin sinuous, lateral margins slightly convex ( Fig. 1B ), reticulation evident, composed of scale-like sculpticells, striae evident throughout the clypeus, punctures sparse, separated by 2– 4X diameter of a puncture; labrum convex, punctation strongly impressed on anterior margin, separated by 1.5–2.0X diameter of a puncture.

Thorax. Pronotum. Anterior margin sinuous, posterior margin slightly curved, lateral margins broad and wrinkled ( Figs 1A,B ); pronotal transverse line strongly impressed with well marked wrinkles anteriorly and posteriorly ( Fig. 1 B–D); pronotal disc with well impressed wrinkles and dense micropunctures ( Figs 1C, D ); punctures present throughout the pronotum, strongly impressed, separated by 1.5–2.0X their diameter ( Fig. 1D ). Elytra. Striae VII–IX sulcate, intervals I–III with linear disposition basally, intervals I–VI convex; stria XI strictly marginal; elytral margin uniform over almost all of its length, narrowing near epipleural apical angle ( Fig. 1A ); lateral margin separated from apex by a plica; fine punctation present among elytral intervals I–XI, distance between the nearest punctures 1.5–2.0X diameter of a puncture ( Fig. 1E ); large punctures of elytral series well marked ( Fig. 1E ); elytral apex rounded to slightly truncate; epipleural angle slightly distinct, sutural angle distinct ( Fig. 1A ). Mesoventrite grooved on lateral margin, apex with anterior margin rounded, groove evident in medial portion, extending to the posterior portion; medial pit present; setae present on anterolateral region. Profemur 3.7X longer than maximum width. Protarsus dorsally convex, broad, 2.6–3.0X longer than wide, about 1/ 3X length of protibia.

Abdomen. Tergite VIII wider than long, apex rounded, with light yellow setae present on the entire surface, with weak longitudinal carina, ending before reaching apex.

Aedeagus ( Fig. 2A ). median lobe of aedeagus shorter than parameres, broad, in dorsal view with lateral margins sinuous, weakly attenuated at the end of basal 2/3 and then broadened in apical 1/3 towards apex, which is slightly triangular and weakly raised medially; width of median lobe about 0.8 times width of apex of parameres; base 1.4 times broader than apex; in lateral view median lobe thick, dorsally curved. Parameres broad, with apex strongly truncate and slightly prominent internal angle.

Female. Sculpture (micropunctures and wrinkles) more evident than in male. Elytral disc free of reticulation, elytral intervals I–XI with fine punctation. Gonocoxae ( Fig. 2B ) elongate, straight, narrowed at middle, with external and internal margins slightly concave, apex truncate, slightly concave; base wider than apex.

Etymology. The specific epithet rhyssonotum refers to the quite evident wrinkles on the pronotum; rhysso (G.) = wrinkled; notum (G.) = the back).

Distribution. This species is currently known only from the Barcelos county, Amazonas State, in northern Brazil ( Fig. 3 A–C).

Habitat. Specimens of this species were collected in streams and pools ( Fig. 3 B–C).

Figures

FIGURE 1. Distribution and habitat of Gyrinus rhyssonotum sp. n.: A) type locality (blue circle) and other record (green square), in Serra do Aracá, Amazonas state, Brazil. B–C) overview of the first-order stream (type locality) where the new species was collected.

FIGURE 2. Gyrinus rhyssonotum sp. n.: A) male adult, dorsal view, scale bar = 1 mm. B) head and pronotum, scale bar = 0.5 mm. C) pronotum, wrinkles. D) pronotum, punctures in the median region. E) elytra, fine punctation between rows of larger punctures.

FIGURE 3. Gyrinus rhyssonotum sp. n.: A) male, dorsal view of the aedeagus, scale bar = 0.2 mm. B) female, dorsal view of gonocoxae, scale bar = 0.2 mm.