Hydrocanthus zimmermanni, Guimarães & Ferreira-Jr & Miller, 2018

Guimarães, Bruno A. C., Ferreira-Jr, Nelson & Miller, Kelly B., 2018, On Hydrocanthus Say, 1823 (Coleoptera: Noteridae): description of a new species, two new synonyms and a key to Brazilian species, Zootaxa 4508 (2), pp. 288-300 : 289-296

Hydrocanthus zimmermanni sp. nov.

( Figs 1 j–k, 3k–l, 4y–aa, 5a, 6a)

Type locality. Peru, Madre de Dios Region, Tambopata River, Explorer’s Inn , 12°50’12.5”S 69°17’36.3”W .

Type material. Holotype ♂. “ PERU, MADRE DE DIOS REGION, Tambopata River, Explorer’s Inn , 12°50’12.5”S 69°17’36.3”W, 10.XII.2003, Miller K.B. leg.” (MSBA). Paratypes. Same data as Holotype (1 ♂ 1 ♀ / MSBA) .

Diagnosis. Hydrocanthus zimmermanni sp. nov. can be distinguished from other species in the genus by the following characteristics: male and female with prosternum laterally and medially setose and prosternal process entirely smooth ( Figs 3 k–l); median lobe of aedeagus, in lateral aspect, with two ridges: one long dorsally on the left side, rising basally, entirely crossing the left surface and extending to the midlength of the ventral margin, and one short dorsal ridge on the right side, rising at distal ¾ of dorsal margin and ending abruptly subapically (Fig. 4z).

Description. Holotype. Body outline, in dorsal view ( Fig. 1j ) oval, broader anteriorly and attenuated posteriorly (TL/MW = 1.95).

Measurements. TL = 4.20 mm; MW = 2.15 mm; AW = 0.55 mm; BW = 0.20 mm; TL/MW = 1.95; AW/BW = 2.75.

Color ( Fig. 1j ). Head and pronotum light yellowish-brown. Elytra very dark reddish-brown from base to midlength, light to dark reddish-brown from after midlength to near apex and light yellowish-brown at apex; marmorations not visible. Ventral surface light yellowish-brown. Apical region of mesofemur and ventral region of metafemur darkened; mesotibia and metatibia entirely darkened.

FIGURE 4. Hydrocanthus species aedeagus. a, d, g, j, m, p, s, v, y) right lateral lobe; b, e, h, k, n, q, t, w, z) median lobe, left lateral aspect; c, f, i, l, o, r, u, x, aa) left lateral lobe. a–c) Hydrocanthus ancus , d–f) Hydrocanthus debilis , g–i) Hydrocanthus guignoti , j–l) Hydrocanthus levigatus , m–o) Hydrocanthus paraguayensis , p–r) Hydrocanthus sharpi , s–u) Hydrocanthus socius , v–x) Hydrocanthus marmoratus , y–aa) Hydrocanthus zimmermanni sp. nov. Scale bar = 0.2 mm.

Sculpture. Head microsculpture consisting of small, regular cells. Pronotum and elytra with shallow, reticulate microsculpture. Prosternum, metaventrite and noterid platform microsculpture consisting of small, regular cells, larger than those in the head. Ventral surface consisting of small, regular cells, as larger as those in prosternum, metaventrite and noterid platform.

Head. Antennae glabrous; antennomeres III–XI subserrate; VII–IX slightly expanded; antennomere XI distally attenuate. Maxillary palps glabrous; apical palpomere elongate, length almost greater than half of total length of palp, distally attenuate, apex truncate, emarginated with two small sensory fields. Labial palps glabrous; apical palpomere rectangular, expanded, length greater than twice the combined length of basal palpomeres, bifid, with sensory field on the medioventral margin, with a second sensory field smaller, round, produced on a small protuberance anteromedial to medial margin.

Thorax. Prosternal process wide (AW/BW = 2.75). Prosternum laterally and medially setose; prosternal process entirely smooth; metaventrite setose in posterior ¼, leaving a glabrous semicircular area anteriorly ( Fig. 3k ). Metaventrite without tubercles. Mesofemur anteroventral margin with fine setose fringe, rising at base and extending to first ¼ of mesofemur as in Figs 5a , 6a (figured is H. levigatus , with similar characters of mesofemur). Mesotarsomere I with semicircular region excavated at base; general shape slightly sinuous near adhesive setae. Adhesive setae ringed by marginal setose corona.

Aedeagus. Median lobe, in lateral aspect, with ventral margin curved in basal half and straight in apical half and truncate apex; with one long dorsal ridge on left side, rising at base, entirely crossing left surface and ceasing at midlength of ventral margin, and one short dorsal ridges on right side, rising at distal ¾ of dorsal margin and abruptly ceasing subapically (Fig. 4z). Left lateral lobe, in lateral aspect, slender, elongated and considerably twisted apically with apex globose and setose along dorsal margin (Fig. 4aa). Right lateral lobe, in lateral aspect, broad and subrectangular (Fig. 4y).

Female. Head and pronotum reddish-brown; elytra entirely very dark reddish-brown ( Fig. 1k ); ventral surface reddish-brown; mesofemur, mesotibia and metafemur without darkened parts.

Variation. Measurements. TL = 4.15–4.45 mm, ♂ = 4.15 mm, ♀ = 4.45 mm; MW = 2.10–2.35 mm; AW = 0.55–0.60 mm; BW = 0.20 mm; TL/MW = 1.75–2.10; AW/BW = 2.75–3.00.

Due to the lack of additional specimens available, it is not possible to assess intraspecific variation.

Taxonomic notes. The distinctive pattern of prosternum and prosternal process setation and aedeagal features of H. zimmermanni sp. nov. makes its identification a relatively simple task, especially if male specimens are available ( Figs 1j , 3k , 4z). However, when only female specimens are available there is a chance of them being mistaken for H. sharpi Zimmermann , 1 928. Females of the two species can be distinguished by their different patterns of metaventrite setation, where in females of H. zimmermanni sp. nov., the metaventrite is setose in the posterior ¼, leaving a glabrous semicircular area anteriorly ( Fig. 3l ), and in females of H. sharpi , the metaventrite is distinctly setose on the sides, leaving a glabrous circular area near the posterior margin and a glabrous subtriangular area anteriorly ( Fig. 3b ).

It is necessary to consider that whereas bicolored elytra are unique within the genus, due to the lack of available specimens, it is not possible to assess whether this characteristic is really a diagnostic feature of Hydrocanthus zimmermanni sp. nov. or it is only related to intraspecific variation.

Etymology. The specific name is an homage to Alois Zimmermann. It is a noun in the nominative singular standing in apposition.

Geographic distribution. So far Hydrocanthus zimmermanni sp. nov. is known only from the region of Madre de Dios, Peru.

Figures

FIGURE 1. Hydrocanthus species dorsal view. a) Hydrocanthus ancus, b) Hydrocanthus debilis, c) Hydrocanthus guignoti, d) Hydrocanthus levigatus, e) Hydrocanthus marmoratus, f) Hydrocanthus paraguayensis male, g) Hydrocanthus paraguayensis female, h) Hydrocanthus sharpi, i) Hydrocanthus socius, j) Hydrocanthus zimmermanni sp. nov. male, k) Hydrocanthus zimmermanni sp. nov. female. Scale bar = 1 mm.

FIGURE 3. Prosternum, prosternal process and noterid platform (metaventrite + metacoxal process), depicting distribution of setae. a) Hydrocanthus sharpi male, b) Hydrocanthus sharpi female, c) Hydrocanthus socius male morphotype A, d) Hydrocanthus socius female morphotype A, e) Hydrocanthus socius male morphotype B, f) Hydrocanthus socius female morphotype B, g) Hydrocanthus marmoratus male morphotype A, h) Hydrocanthus marmoratus male morphotype B, i) Hydrocanthus marmoratus female morphotype A, j) Hydrocanthus marmoratus female morphotype B, k) Hydrocanthus zimmermanni sp. nov. male, l) Hydrocanthus zimmermanni sp. nov. female. Scale bar = 2 mm.

FIGURE 5. Hydrocanthus species male left mesofemur in dorsal view. a) Hydrocanthus levigatus, b) Hydrocanthus debilis, c) Hydrocanthus sharpi. Scale bar = 0.2 mm.

FIGURE 6. Hydrocanthus species male left middle leg in dorsal view. a) Hydrocanthus levigatus, b) Hydrocanthus debilis, c) Hydrocanthus sharpi. Scale bar = 0.5 mm.