Exocelina oiwa 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

8. Exocelina oiwa Shaverdo & Balke sp. nov. Figs 12 , 18

Type locality.

Papua New Guinea: Morobe Province, Aseki, Oiwa (a village about 100 km to the west of Bulolo), 7°18'00.0"S, 146°14'00.0"E, 1600-1700 m a.s.l.

Type material.

Holotype: male "PAPUA N. G.: Morobe Prov. Aseki, Oiwa, 1600-1700 m, 11.-12.3.1998 leg. A. Riedel" (NHMW). Paratypes: 4 males, 2 females with the same labels as the holotype, one male and one female additionally with labels "SEM 19" (NHMW, ZSM).

Description.

Body size and form: Beetle small: TL-H 3.3-3.5 mm, TL 3.7-3.95 mm, MW 1.85-1.95 mm (holotype: TL-H 3.5 mm, TL 3.95 mm, MW 1.95 mm), with oblong-oval habitus.

Colouration: Fast uniformly reddish brown. Head reddish brown, darker posterior eyes. Pronotum reddish brown, slightly darker on disc. Elytra reddish brown, sometimes slightly darker than pronotum. Head appendages and legs proximally yellowish, legs distally darker, reddish ( Fig. 12 ).

Surface sculpture: Submatt dorsally, with strong and dense punctation and strongly impressed microreticulation. Head with dense and coarse punctation (spaces between punctures 0-1 times size of punctures); diameter of punctures equal to or larger than diameter of cells of microreticulation. Pronotum and elytra with finer and sparser punctation than on head, very distinct, more even on elytra. Pronotum and elytra with strongly impressed microreticulation; head with microreticulation stronger. Metaventrite, metacoxae, and abdominal ventrites distinctly microreticulate, but shiny. Metacoxal plates with longitudinal strioles and weak transverse wrinkles; abdominal ventrites with strioles. Punctation on venter weak; more distinct on two last abdominal ventrites.

Structures: Pronotum with 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 bead and few setae laterally. Abdominal ventrite 6 broadly rounded or slightly truncate.

Male: Protarsomere 4 with anterolateral seta rather long and thin, evenly curved, equal to laterally situated large seta. Protarsomere 5 ventrally with anterior band of ca. 60 and posterior row of five relatively long setae ( Fig. 18D ). Abdominal ventrite 6 with 8-9 lateral striae on each side. Median lobe short, evenly tapering to apex in lateral and ventral views, very tip of apex thickened dorsally ( Fig. 18A, B ). Paramere as in Fig. 18D .

Female: Without evident differences in external morphology from males, except for not modified protarsi and abdominal ventrite 6 without striae.

Affinities.

From the species co-occurring in the same area (from E. danae , E. ekari , E. broschii , and E. ullrichi groups), E. oiwa sp. nov. can be distinguished by its size, dorsal punctation and colouration, shape and setation of its median lobe and paramere, and thin, evenly curved anterolateral seta of the protarsomere 4. The species is especially similar to E. aseki sp. nov., from which it can be distinguished by shape of its median lobe. For the affinities within the group, see the “Key”.

Distribution.

Papua New Guinea: Morobe Province ( Fig. 25 ).

Etymology.

The species is named after Oiwa 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.