Exocelina piusi 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 : 29-32

16. Exocelina piusi Shaverdo & Balke sp. n. Figs 9, 33

Exocelina undescribed sp. MB4921: Toussaint et al. 2014: supplementary figs 1-4, table 2; Toussaint et al. 2015: supplementary figs S1-S2, table S3.

Exocelina piusi _ New_Guinea_MB4921: Toussaint et al. 2015: supplementary information S5-S6.

Type locality.

Papua New Guinea: East Sepik Province, Lembena, 04°56.859'S, 143°59.375'E, 1,250 m a.s.l.

Type material.

Holotype: male "Papua New Guinea: East Sepik, Lembena, 335m, 10.ix.2009, 04 56.859S 143 59.375E, Ibalim & Pius (PNG250)", "M. Balke 4920" (ZSM). Paratype: 1 male with the same label as the holotype, "M. Balke 4921" (ZSM).

Description.

Body size and form: Beetle small: TL-H 3.5-3.6 mm, TL 3.9-4.0 mm, MW 1.95-2.0 mm (holotype: TL-H 3.6 mm, TL 4 mm, MW 1.95 mm), with oblong-oval habitus.

Coloration: Specimens teneral. Reddish brown, with pronotum slightly paler. Head reddish brown, with small darker areas posterior to eyes. Pronotum yellowish brown, darker on disc. Elytra reddish brown. Head appendages yellowish red, legs reddish, distally darker, especially metathoracic legs (Fig. 9).

Surface sculpture: Submatt dorsally. Head with fine, sparse punctation (spaces between punctures 2-3 times size of punctures), only with some larger punctures between eyes; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum and elytra with very fine, sparse punctation. Pronotum and elytra with rather strongly impressed microreticulation. Head with microreticulation stronger. Metaventrite 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 with narrow lateral bead. Its lateral sides with inconspicuous, shallow longitudinal impressions. 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 lateral bead and few setae. Abdominal ventrite 6 rounded.

Male: Antennae simple (Fig. 9). Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 long and narrow, with anterior band of ca 40 and posterior row of 6 relatively long, thin setae (Fig. 33D). Median lobe in lateral view slightly curved, broad, with apex bent downwards, not distinctly thickened, slightly angulate; in ventral view, almost subparallel and distally distinctly narrowed to apex, apex roundly truncate, of shape of a baby pacifier. Paramere slightly concave on dorsal side, with long, dense dorsal setae: subdistal setae strong and dense, setae in middle part shorter and sparser, proximal setae longer and stronger than subdistal ones (Fig. 33 A–C). Abdominal ventrite 6 with 9-10 lateral striae on each side.

Female: Unknown.

Affinities.

Exocelina piusi sp. n. is similar to E. messeri and, especially, to E. pseudofume sp. n. in body shape, coloration, and dorsal punctation and microreticulation, but differs from them in presence of narrow pronotal bead and shape of the median lobe.

Distribution.

Papua New Guinea: East Sepik Province (Fig. 50).

Etymology.

The species is named for Pius, a local collector. The species name is a noun in the genitive case.