Exocelina marawaka Shaverdo & Balke

Shaverdo, Helena, Sagata, Katayo & Balke, Michael, 2016, Taxonomic revision of New Guinea diving beetles of the Exocelinadanae group, with the description of ten new species (Coleoptera, Dytiscidae, Copelatinae), ZooKeys 619, pp. 45-102 : 69

Taxon classification Animalia Coleoptera Dytiscidae

11. Exocelina marawaka Shaverdo & Balke sp. n. Figs 20, 35

Exocelina undescribed sp. MB1366: Toussaint et al. 2014: supplementary figs 1-4, tab. 2.

Type locality.

Papua New Guinea: Eastern Highlands Province, Marawaka, Ande, 07°01.70'S; 145°49.81'E, 1700 m a.s.l.

Type material.

Holotype: male "Papua New Guinea: Eastern Highlands, Marawaka, Ande, 1700m, 8.xi.2005, 07.01.697S 145.49.807E, Balke & Kinibel (PNG 86)" (ZSM). Paratypes: Eastern Highlands: 32 males, 17 females with the same label as the holotype, one male with a green label "DNA M.Balke 1366" (NHMW, ZSM). 8 males, 6 females "Papua New Guinea: Eastern Highlands, Marawaka, Ande, 1700-1800m, 9.xi.2006, 07.01.697S 145.49.807E, Balke & Kinibel (PNG 87)" (NHMW, ZSM). Gulf: 1 female "Papua New Guinea: Gulf, Marawaka, Andakombe towards Morobe, 2160m, 12.xi.200, 07.11.717S 145.51.177E, Balke & Kinibel (PNG 94)", "DNA M.Balke 1370" [green] (ZSM).

Diagnosis.

Beetle medium-sized, piceous, with paler sides of pronotum; dorsal surface with fine punctation and evident microreticulation, shiny; pronotum with distinct lateral bead; male antennomeres simple; protarsomere 4 with weakly curved anterolateral hook-like seta, smaller than more laterally situated large seta; median lobe evidently broadened in distal part, broadly pointed to apex in ventral view and with slightly curved, rounded apex in lateral view, on both lateral sides with numerous fine setae situated linearly on anterior half of distal part of median lobe under fine carina; paramere without notch on dorsal side. The species is similar to Exocelina posmani sp. n. but differs from it mainly in the structure of the median lobe: apex longer and narrower in lateral view and pointed in ventral view, distal setae not arranged into one area but situated linearly along the lateral margin.

Description.

Size and shape: Beetle medium-sized (TL-H 4.05-4.6 mm, TL 4.4-5.0 mm, MW 2.15-2.45 mm), with oblong-oval habitus, broadest at elytral middle. Coloration: Head uniformly dark brown to piceous; pronotum dark brown to piceous, paler on sides; elytra uniformly piceous; ventrally dark brown; head appendages and legs proximally yellowish red, legs distally darker, reddish brown (Fig. 35).

Surface sculpture: Head with relatively dense and coarse punctation (spaces between punctures 1-3 times size of punctures); diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with finer, sparser, and more evenly distributed punctation than on head. Elytra with much finer, sparser punctation than on pronotum. Pronotum and elytra with distinct microreticulation, dorsal surface shiny. Head with microreticulation slightly stronger. Metaventrite, metacoxa, and abdominal ventrites distinctly microreticulate. Metacoxal plates with longitudinal strioles and transverse wrinkles; abdominal ventrites with strioles. Ventrum 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, not rounded anteriorly, without anterolateral extensions. Blade of prosternal process lanceolate, relatively narrow, convex, with distinct bead and few setae laterally; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 broadly rounded or slightly truncate.

Male: Antenna simple. Protarsomere 4 with very small (smaller than more laterally situated large seta), weakly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of 27 setae and posterior row of 5 short, relative thick setae (Fig. 20A). Abdominal ventrite 6 with 7-10 lateral striae on each side. Median lobe evidently broadened in distal part, braodly pointed to apex in ventral view and with slightly curved, rounded apex in lateral view, on both lateral sides with numerous fine setae situated linearly on anterior half of distal part of median lobe under fine carina (Fig. 20 B–C). Paramere without notch, slightly concave on dorsal side, with thin, sparse, inconspicuous proximal setae and thicker, denser, and longer subdistal setae (Fig. 20D).

Holotype: TL-H 4.5 mm, TL 4.9 mm, MW 2.2 mm.

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

Variability.

Elytral punctation varies from inconspicuous to distinct.

Distribution.

Papua New Guinea: Eastern Highlands and Gulf Provinces. The species is known only from the Marawaka area (Fig. 40).

Etymology.

The species is named after the Marawaka area. The name is a noun in the nominative singular standing in apposition.