Exocelina sima Shaverdo & Balke

Shaverdo, Helena, Sagata, Katayo & Balke, Michael, 2018, Introduction of the Exocelinacasuarina-group, with a key to its representatives and descriptions of 19 new species from New Guinea (Coleoptera, Dytiscidae, Copelatinae), ZooKeys 803, pp. 7-70 : 35-37

20. Exocelina sima Shaverdo & Balke sp. n. Figs 8, 31

Type locality.

Papua New Guinea: Simbu/Eastern Highlands Province, Crater Mountain, Sera - Herowana, Sima River, ca 06°06'57.5"S, 145°03'39.4"E, 1,250 m a.s.l.

Type material.

Holotype: male "Papua New Guinea: Simbu / EHP, Crater Mountain, Sera - Herowana, Sima river, 1250m, 15IX2002, Balke & Sagata, (PNG 016)" (ZSM).

Description.

Body size and form: Beetle small: TL-H 3.6 mm, TL 4.0 mm, MW 2.0 mm, with broader, oval habitus.

Coloration: Reddish brown head and pronotum and piceous elytra. Head reddish in its anterior half and dark brown in posterior one. Pronotum dark brown on disc and gradually paler to yellowish red laterally. Elytra dark brown, paler laterally and almost piceous on disc. Head appendages yellowish red, legs reddish, distally darker, especially metathoracic legs (Fig. 8).

Surface sculpture: Shiny dorsally. Head with rather dense punctation (spaces between punctures 1-2 times size of punctures) but fine punctation; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum and elytra with distinct punctation, sparser and finer punctation than on head. Pronotum and elytra with weakly impressed microreticulation. Head with microreticulation stronger. Metaven trite and metacoxae distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal ventrites with distinct microreticulation, strioles, and very fine sparse punctation.

Structures: Pronotum without lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, rounded anteriorly. Blade of prosternal process lanceolate, elongate, relatively broad, slightly convex, with distinct lateral bead and few. Abdominal ventrite 6 rounded.

Male: Antennae simple (Fig. 8). Protarsomere 4 with anterolateral seta long and thin, equal to more laterally situated large setae, slightly curved downwards. Protarsomere 5 long and narrow, with anterior band of more than 40 and posterior row of 12 relatively long, thin setae (Fig. 31D). Median lobe in lateral view short, slightly curved, with enlarged, rounded, not bent downwards apex; in ventral view, narrow, subparallel, and with truncate apex. Paramere very slightly concave on dorsal side and with long, dense, thin setae, situated along dorsal margin: subdistal setae strong and dense, setae in middle part shorter and sparser, proximal setae long but sparser than subdistal ones (Fig. 31 A–C). Abdominal ventrite 6 without lateral striae on each side, except one with setae.

Female: Unknown.

Affinities.

In absence of the pronotal bead and thin and not hook-like anterolateral seta of the male protarsomere 4, Exocelina sima sp. n. is similar to E. keki sp. n., E. messeri , and E. pseudofume sp. n. However, the species distinctly differs from them in more oval body form and more strongly expressed bicolor dorsal surface: reddish head and pronotum and piceous elytra, as well as in a characteristic shape of the median lobe and male abdominal ventrite 6 without lateral striae. The latter character is unique among New Guinea Exocelina .

Distribution.

Papua New Guinea: Simbu and Eastern Highlands Provinces, Crater Mountain. This species is known only from the type locality (Fig. 50).

Etymology.

The species is named after Sima River. The name is a noun in the nominative singular standing in apposition.