Exocelina akameku 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

5. Exocelina akameku Shaverdo & Balke sp. nov. Figs 13 , 19

Type locality.

Papua New Guinea: Madang Province, Akameku - Brahmin, Bismarck Range, 05°49.89'S, 145°24.49'E, 750 m a.s.l.

Type material.

Holotype: male "Papua New Guinea: Madang, Akameku - Brahmin, Bismarck Range, 750m, 25.xi.2006, 05.49.892S 145.24.491E, Balke & Kinibel (PNG 113)" (ZSM).

Description.

Body size and form: Beetle small: TL-H 3.35 mm, TL 3.8 mm, MW 1.8 mm, with oblong-oval habitus.

Colouration: Dark brown, with reddish pronotal sides and head anteriorly. Head reddish brown, paler anteriorly; pronotum dark brown on disc, with reddish sides; elytra dark brown, with weakly indicated reddish sutural lines; head appendages and legs proximally yellowish, legs distally darker, reddish brown ( Fig. 13 ).

Surface sculpture: Shiny dorsally, with weak and sparse punctation and weakly impressed microreticulation. Head with fine and sparse punctation (spaces between punctures 2-3 times size of punctures); diameter of punctures equal to or smaller than diameter of cells of microreticulation. Pronotum with much finer and sparser punctation than on head, very inconspicuous. Punctation on elytra invisible. Pronotum and elytra with weakly impressed 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. Punctation on venter invisible; inconspicuous on two last abdominal ventrites.

Structures: Pronotum with narrow lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, very slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively narrow, slightly convex, with distinct bead and few setae laterally. Abdominal ventrite 6 slightly truncate.

Male: Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of more than 30 and posterior row of 7 relatively long setae ( Fig. 19D ). Abdominal ventrite 6 with 7-8 lateral striae on each side. Median lobe short, robust, evenly tapering to slightly pointed apex in lateral and ventral views; apex slightly sinuate in lateral view ( Fig. 19A, B ). Paramere as in Fig. 19C .

Female: Unknown.

Affinities.

From the species co-occurring in the same area (from E. danae , E. ekari , E. broschii , and E. ullrichi groups), E. akameku sp. nov. can be distinguished by its size, dorsal punctation, and shape and setation of its median lobe and paramere. For the affinities within the group, see the “Key”.

Distribution.

Papua New Guinea: Madang Province, Bismarck Range ( Fig. 25 ).

Etymology.

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

Figures

Figure 25. Map of the eastern part of New Guinea showing distribution of the species of the E. bacchusi group.

Figures 12 - 17. Habitus and colouration 12 Exocelina oiwa sp. nov. 13 E. akameku sp. nov. 14 E. erteldi (Balke, 1998) 15 E. oksibilensis sp. nov. 16 E. bacchusi (Balke, 1998) 17 E. bacchusi herzogensis sp. nov.

Figures 18, 19. 18 Exocelina oiwa sp. nov. 19 E. akameku 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.