Exocelina okbapensis Shaverdo & Balke

Shaverdo, Helena, Sumoked, Bob & Balke, Michael, 2017, Descriptions of two new species and one new subspecies from the Exocelinaokbapensis-group, and notes on the E. aipo-group (Coleoptera, Dytiscidae, Copelatinae), ZooKeys 715, pp. 17-37 : 21-23

1. Exocelina okbapensis Shaverdo & Balke sp. n. Figs 2, 5

Sp. 4: Balke 1998: 338.

Type locality.

Papua: Pegunungan Bintang Regency, Ok Bap, 4°49'28.6"S; 140°24'47.0"E, 1961 m a.s.l.

Type material.

Holotype: male "Indonesia: Papua, nr Ok Bab [sic!], 1961m, 8.vi.2015, -4,82460033148527 140.413050251081, Sumoked (Pap049)" (MZB). Paratypes: Indonesia: Papua: 10 males and 6 females with the same label as the holotype (MZB, NHMW, ZSM). 3 males, 3 females "Indonesia: Papua, nr Ok Bab, 2121 m, 8.vi.2015, -4,84880341216921 140,367602147161, Sumoked (Pap050)", one male and one female with additional labels with green text "M. Balke 7002" and "M. Balke 7003" (NHMW, ZSM). 3 males, 2 females "Indonesia: Papua, N Ok Sibil, 1564m, 10.vi.2015, -4,87003368 140,64401, Sumoked (Pap052)", two males with additional labels with green text "M. Balke 7000" and "M. Balke 6999" (NHMW, ZSM). PNG: Sandaun: 1 male "PAPUA, Selminumtem [Selminum Tem, 45 km SWS Telefomin, ca. 5°S; 141°15'E], W.Sepik d. P.Beron leg.", " Copelatus nomax J.B.Br. det.V. Guéorguiev 1917" [partly hw] (NHMW). 1 male "PAPUA N.G.: Sandaun Prov. Telefomin, 16.-17.5.1998 trail to Eliptamin 1700-1800 m; leg. Riedel" (NHMW).

Diagnosis.

Beetle medium-sized; usually piceous, with brown pronotal sides; more or less shiny to submatt; pronotum with distinct lateral bead; antennomeres simple or stout; male protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta; male protarsomere 5 long and narrow, without concavity, with anterior row of 18-27 and posterior row of eight relatively short setae; median lobe curved, with apex curved downwards and slightly rounded in lateral view. The species is similar to E. me but its protarsomere 5 is not modified. From E. may sp. n., it differs in a large, strongly curved anterolateral hook-like seta of the male protarsomere 4.

Description.

Size and shape: Beetle small to medium-sized (TL-H 3.35-4.5 mm, TL 3.7-4.9 mm, MW 1.75-2.4 mm for Papua populations), with oblong-oval habitus, broadest at elytral middle. Medium-sized specimens more common. Coloration: Head, disc of pronotum and elytra dark brown to piceous, pronotal sides broadly reddish brown, some specimens with narrow reddish sutural lines; head appendages and legs reddish brown, distally darker (Fig. 2). Teneral specimens paler.

Surface sculpture: Head with dense punctation (spaces between punctures 1-2 times size of punctures), finer and sparser anteriorly; diameter of punctures equal to diameter of cells of microreticulation. Pronotum and elytra with distinct punctation, sparser and finer than on head. Elytral punctation slightly sparser than pronotal one. Pronotum and elytra with evident microreticulation, dorsal surface more or less shiny to submatt. Head with microreticulation stronger. Metaventrite and metacoxa distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal ventrites with distinct microreticulation, strioles, and very fine sparse punctation.

Structures: Pronotum with distinct lateral bead. 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; neck and blade of prosternal process evenly joined. Abdominal ventrite 6 broadly rounded.

Male: Antennae simple or stout (Fig. 2). Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior row of 18-27 and posterior row of 8 relatively short setae (Fig. 5D). Median lobe curved, with apex curved downwards and slightly rounded in lateral view and evenly tapering to the broadly pointed apex in ventral view. Paramere with distinct notch on its dorsal side and small, evidently separated subdistal part with a tuft of very dense, strong setae; proximal setae inconspicuous, strongly reduced in some specimens (Fig. 5 A–C). Abdominal ventrite 6 with 5-16 long lateral striae on each side.

Holotype: TL-H 4.2 mm, TL 4.6 mm, MW 2.25 mm.

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

Variability.

In some males, antennomeres 2-6 slightly thicker, stout. Some specimens have the dorsal microreticulation more strongly impressed. Two specimens from Sandaun are smaller than most of the Papua specimens (TL-H 3.3-3.65 mm, TL 3.7-4.1 mm, MW 1.75-1.95 mm) and have less dense subdistal setae on the paramere.

Distribution.

Papua: Pegunungan Bintang Regency and Papua New Guinea: Sandaun Province (Fig. 12).

Habitat.

Near Ok Bap, the species was collected in small creeks as well as in slowly flowing, sun exposed irrigation ditches along road.

Etymology.

The species is named after Ok Bap, where most of the specimens were collected. The name is an adjective in the nominative singular.