Exocelina riberai Shaverdo, Surbakti & Balke, 2021

Shaverdo, Helena, Surbakti, Suriani, Sumoked, Bob & Balke, Michael, 2021, Seven new species of the Exocelina ekari group from New Guinea central and coastal mountains (Coleoptera, Dytiscidae, Copelatinae), ZooKeys 1026, pp. 45-67 : 45

Exocelina riberai Shaverdo, Surbakti & Balke sp. nov. Figures 3 , 7 , 15

Exocelina “Foja” #7282: Toussaint et al. 2021: figs 3-6.

Type locality.

Indonesia: Papua Province, Sarmi Regency, Foja Mts, N Waaf Village , 02°22'29.6"S, 138°44'19.9"E, 115 m a.s.l.

Type material.

Holotype: male " Indonesia: Papua, Foja Mountains N foot, N Waaf vill, 115m, 23.v.-3.vi.2016, -2.374874 138.738855, Sumoked (Pap060)" ( MZB) .

Paratypes: 3 males, 5 females with the same label as the holotype ( MZB, KSP) . 2 males " Indonesia: Papua, Foja Mountains N foot, N Waaf vill, pondok, 150m, 4.-7.vi.2016, -2.406142 138.74399, Sumoked (Pap061)", one male with an additional green text label “7282” ( KSP) .

Description.

Body size and form: Beetle small to medium-sized: TL-H 3.45-3.85 mm, TL 3.8-4.3 mm, MW 1.85-2.1 mm (holotype: TL-H 3.6 mm, TL 4.1 mm, MW 1.9 mm), with oblong-oval habitus (Fig. 3 ).

Colouration: Dorsally dark brown to piceous, usually with paler, reddish brown, head and pronotum (Fig. 3 ). Head reddish brown, reddish anteriorly, dark brown around eyes; pronotum reddish brown to brown, with darker, to dark brown, disc; elytra dark brown, sometimes with reddish brown sutural lines; head appendages yellow, legs yellowish red to reddish brown. One specimen (from locality Pap061) piceous, with dark brown pronotal lateral sides. Most specimens from locality Pap060 teneral, therefore, paler.

Surface sculpture: Shiny dorsally, with inconspicuous, almost invisible elytral punctation and weakly impressed microreticulation. Head with relatively fine and sparse punctation (spaces between punctures 1-4 times size of punctures); diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with finer, sparser, and more evenly distributed punctation than on head, often inconspicuous. Elytra with very sparse and fine punctation, almost invisible. Elytra with weakly impressed microreticulation; pronotum and especially head with stronger microreticulation. Metaventrite and metacoxa distinctly but weakly microreticulate, metacoxal plates with longitudinal strioles and very weak transverse wrinkles. Abdominal ventrites with weak microreticulation, strioles, and punctation visible only on two last abdominal ventrites.

Structures: Pronotum without lateral bead, in some specimens (especially characteristic for females) with bead traces or even with narrow bead on lateral sides of pronotum. Base of prosternum and neck of prosternal process with distinct ridge, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct lateral bead and few setae. Abdominal ventrite 6 broadly rounded.

Male: Antenna simple. Pro- and mesotarsomeres 1-3 not dilated, narrow. Protarsomere 4 cylindrical, narrow, with medium-sized, thick, distinctly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior row of ten and posterior row of five short setae (Fig. 7A ). Median lobe with distinctly discontinuous outline; in lateral view, almost straight, with apex narrow, curved downwards, and strongly protruding at tip forming a long thin prolongation; in ventral view, with weak submedian constriction, distal part narrower than proximal one, apex slightly and evenly concave, with distinct protruding tip (Fig. 7B, C ). Paramere with strong notch on dorsal side and subdistal part subquadrate, large and broad; subdistal setae dense, rather short, flattened; proximal setae hair-like, numerous, dense, and long (Fig. 7D ). Abdominal ventrite 6 broadly rounded, with 13-16 lateral striae on each side.

Female: Pro- and mesotarsi not modified. Abdominal ventrite 6 without lateral striae. Bead traces or even with narrow bead on lateral margins pronotum present in majority of females.

Affinities.

The new species evidently belongs to the E. ekari group due to the discontinuous outline of its median lobe. The species is similar to E. pinocchio Shaverdo & Balke, 2014 in general appearance and shape of median lobe, but differs from it in more straight apical prolongation of the median lobe and in subquadrate, large and broad subdistal part of the paramere (distinctly more elongate in E. pinocchio ) and its setation.

Distribution.

Indonesia: Papua Province. This species is known only from Foja Mountains , from and near the type locality (Fig. 15 ) .

Habitat.

The specimens were collected from shaded waterholes on a riverbank.

Etymology.

The species is named to honour Dr Ignacio Ribera Galán, a leading water beetle specialist and our dear colleague who passed away on 15 April 2020. The name is a noun in the genitive case.

Figures

Figure 15. Map of the western part of New Guinea showing the species distribution.

Figures 1 - 4. Habitus and colouration of holotype 1 Exocelina foja sp. nov. 2 E. waaf sp. nov. 3 E. riberai sp. nov. 4 E. apistefti sp. nov.

Figures 7, 8. 7 Exocelina riberai sp. nov., holotype 8 E. apistefti sp. nov., holotype A right protarsomeres 4 and 5 in ventral view B median lobe in ventral view C median lobe in lateral view D right paramere in external view.