Exocelina koroba Shaverdo & Balke

Shaverdo, Helena, Surbakti, Suriani, Warikar, Evie L., Sagata, Katayo & Balke, Michael, 2019, Nine new species groups, 15 new species, and one new subspecies of New Guinea diving beetles of the genus Exocelina Broun, 1886 (Coleoptera, Dytiscidae, Copelatinae), ZooKeys 878, pp. 73-143 : 73

2. Exocelina koroba Shaverdo & Balke sp. nov. Figs 2 , 8

Exocelina undescribed sp. MB1292: Toussaint et al. 2014: supplementary figs 1-4, tab. 2; Toussaint et al. 2015: supplementary figs S1, S2, tab. S3, and information S5, S6.

Type locality.

Papua New Guinea: Hela Province, Hedamali, ca. 05°41.85'S, 142°43.84'E, 1700-1900 m a.s.l.

Type material.

Holotype: male "PAPUA N.G.: 6.-9.5.1998 Southern Highl. Prov. Tari-Koroba, Hedemari [Hedamali] 1700-1900 m, leg. Riedel" (NHMW). Paratypes: 1 male "Papua New Guinea: Southern Highlands, Koroba, 1600 m, 15.v.1994, 05.41.854S 142.43.836E, Balke (PNG 66)", "DNA M Balke 1292" (ZSM).

Description.

Body size and form: Beetle medium-sized: TL-H 3.95-4.4 mm, TL 4.4-4.55 mm, MW 2.2-2.35 mm (holotype: TL-H 3.95 mm, TL 4.4 mm, MW 2.2 mm), with oblong-oval habitus.

Colouration: Piceous, with paler sides of pronotum. Head piceous, paler anteriorly; pronotum piceous, with brown sides; elytra piceous, with reddish sutural lines; head appendages and legs proximally reddish, legs distally darker, reddish brown ( Fig. 2 ). Teneral specimen paler, brown.

Surface sculpture: Submatt dorsally, with relatively dense and coarse punctation and evident microreticulation. Head with relatively dense and coarse punctation (spaces between punctures 1-2 times size of punctures); diameter of punctures almost equal to diameter of cells of microreticulation. Pronotum with finer, sparser punctation, and more evenly distributed punctation than on head. Elytra with coarser punctation than on pronotum. Pronotum and elytra with distinct microreticulation. Head with microreticulation slightly stronger. Metaventrite, metacoxae, and abdominal ventrites distinctly microreticulate. Metacoxal plates with longitudinal strioles and weak transverse wrinkles; abdominal ventrites with strioles. Venter with inconspicuous punctation, more evident on metacoxal plates and two last abdominal ventrites.

Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, slightly rounded and with few transverse strioles anteriorly, without anterolateral extensions. Blade of prosternal process lanceolate, relatively broad, convex, with distinct bead and few setae laterally. Abdominal ventrite 6 slightly truncate.

Male: Protarsomere 4 with rather small, slightly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior row of 23 short setae and posterior row of 6 setae ( Fig. 8D ). Abdominal ventrite 6 with 12-15 lateral striae on each side. Median lobe slightly curved, with apex thick, short, pointed and strongly curved downwards in lateral view ( Fig. 8 A–B ). Paramere with distinct notch on dorsal side, subdistal part relatively large, rounded, with dense and strong setae, proximal setae thin and sparse, inconspicuous. ( Fig. 8C ).

Female: Unknown.

Affinities.

The species can be distinguished from the species co-occurring in the same area ( E. pseudoedeltraudae Shaverdo & Balke, 2014, E. tariensis Shaverdo & Balke, 2014, E. marinae (Shaverdo, Sagata & Balke, 2005), and E. pseudomarinae Shaverdo, Sagata & Balke, 2016) by size, relatively dense and coarse dorsal punctation, not modified male antennae, and the shape and setation of its median lobe and paramere.

Distribution.

Papua New Guinea: Hela Province, Koroba area ( Fig. 11 ).

Etymology.

The species is named after Koroba Village. The name is a noun in the nominative singular standing in apposition.

Figures

Figure 8. Exocelina koroba sp. nov. A median lobe in ventral view B median lobe in lateral view C paramere in external view D male protarsomeres 4 - 5 in ventral view.

Figure 11. Map of the eastern part of New Guinea showing distribution of the species of the monotypic groups.

Figures 1 - 4. Habitus and colouration 1 Exocelina aipomek (Balke, 1998) 2 E. mekilensis sp. nov. 3 E. koroba sp. nov. 4 E. morobensis sp. nov.