Exocelina apistefti 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 apistefti Shaverdo, Surbakti & Balke sp. nov. Figures 4 , 8 , 15

Exocelina nr. brahminensis #7287: Toussaint et al. 2021: figs 3-6.

Type locality.

Indonesia: Papua Province, Sarmi Regency, Foja Mts , 02°34'18.6"S, 138°43'02.1"E, 1700 m a.s.l.

Type material.

Holotype: male " Indonesia: Papua, Foja Mountains , bog camp, 1700m, 23.v.-3.vi.2016, -2.571839 138.717250, Sumoked (Pap058)", “7287” [green text] ( MZB) .

Paratypes: 2 females with the same label as the holotype ( KSP) . 1 male, 1 female " Indonesia: Papua, Foja Mountains , river camp, 1600m, 23.v.-3.vi.2016, -2.561006 138.711487, Sumoked (Pap059)" ( MZB, KSP) .

Description.

Body size and form: Beetle small: TL-H 3.45-3.7 mm, TL 3.8-4.05 mm, MW 1.85-2 mm (holotype: TL-H 3.5 mm, TL 3.9 mm, MW 1.9 mm), with oblong-oval habitus (Fig. 4 ).

Colouration: Dorsally piceous, with paler lateral sides of pronotum (Fig. 4 ). Head piceous, with slightly paler, dark brown, anterior margin; pronotum piceous, slightly paler towards lateral sides, lateral sides brown to dark brown, yellowish to reddish brown at anterior angles; elytra uniformly piceous; head appendages and proximal part of legs yellowish brown, legs distally brown.

Surface sculpture: Shiny dorsally, with fine microreticulation and almost invisible punctation on elytra. Head with dense and coarse punctation (spaces between punctures 0-3 times size of punctures), distinctly finer and sparser anteriorly and posteriorly; diameter of punctures equal to diameter of cells of microreticulation. Pronotum with distinctly finer and sparser punctation than on head. 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 transverse wrinkles. Abdominal ventrites with weak microreticulation, strioles, and fine sparse punctation, coarser and denser on two last abdominal ventrites.

Structures: Pronotum without lateral bead. Base of prosternum and neck of prosternal process with ridge, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively narrow, slightly convex medially, with distinct bead and few setae. Abdominal ventrite 6 broadly rounded apically.

Male: Antenna simple. Pro- and mesotarsomeres 1-3 not dilated, narrow. Protarsomere 4 cylindrical, narrow, with medium-sized, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior row of 13 and posterior row of six short setae (Fig. 8A ). Median lobe with distinctly discontinuous outline; in lateral view, almost straight, with apex broad, curved downwards, and pointed at tip; in ventral view, with distinct submedian constriction, distal part narrower than proximal one, apex deeply and narrowly concave (Fig. 8B, C ). Paramere with strong notch on dorsal side, with median notch tip sharply pointed, and subdistal part large and elongate; subdistal setae long and dense, of two kind: more numerous upper ones thin and lower setae shorter, thicker and flattened; proximal setae hair-like, distinctly more inconspicuous than subdistal ones (Fig. 8D ). Abdominal ventrite 6 broadly rounded, with 9-11 lateral striae on each side.

Female: Pro- and mesotarsi not modified. Abdominal ventrite 6 without striae.

Affinities.

The species evidently belongs to the E. ekari group due to the discontinuous outline of its median lobe. The species is very similar to E. brahminensis Shaverdo et al., 2012 in general appearance and structure of male genitalia, especially in the sharply pointed median notch tip of paramere, but differs from it in lager size (TL-H 3.15-3.3 mm for E. brahminensis ), darker dorsal colouration, shape of the median lobe, and paramere 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 small, shallow forest creeks.

Etymology.

The species name Exocelina apistefti derives from Greek απίστευτος (feminine απίστευτη) meaning unbelievable. The name is an adjective in the nominative singular.

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.