Exocelina bewani 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 : 13

3. Exocelina bewani Shaverdo & Balke sp. n. Figs 13, 37

Exocelina undescribed sp. MB1296: Toussaint et al. 2014: supplementary figs 1-4, table 2; Toussaint et al. 2015: supplementary figs S1-S2, table S3.

Exocelina bewani _New_Guinea_MB1296: Toussaint et al. 2015: supplementary information S5-S6.

Type locality.

Papua New Guinea: Sandaun Province, Bewani Mts, approximately 03°05.13'S, 141°10.23'E., 400 m a.s.l.

Type material.

Holotype: male "Papua New Guinea: Sandaun, Bewani Stn., limestone creek@base of Bewani Mts., 400 m, 12.iv.2006, nr. 03.05.130S 141.10.227E, Balke & Sagata (PNG 39)", "M.Balke 1296" [green] (ZSM). Paratypes: 2 males, 1 female with the same label as the holotype (NHMW, ZSM).

Description.

Body size and form: Beetle small: TL-H 3.05-3.25 mm, TL 3.35-3.55 mm, MW 1.8-1.9 mm (holotype: TL-H 3.05 mm, TL 3.35 mm, MW 1.8 mm), with broader, oval habitus.

Coloration: Brownish, with head and pronotum paler. Head reddish brown to brownish, sometimes paler anteriorly. Pronotum reddish brown on sides, brown to dark brown on disc. Elytra brown to dark brown, sometimes with narrow reddish sutural lines. Head appendages yellowish red, legs reddish, distally darker, especially metathoracic legs (Fig. 13).

Surface sculpture: Shiny but with dense, distinct punctation dorsally. As in E. sumokedi sp. n.

Structures: Pronotum with lateral bead. Its lateral sides with shallow longitudinal impressions. Base of prosternum and neck of prosternal process with distinct ridge, narrowly rounded anteriorly. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct lateral bead and few setae. Abdominal ventrite 6 slightly truncate.

Male: Antennae simple (Fig. 13). Protarsomere 4 with medium-sized, thick, curved anterolateral hook-like seta. Protarsomere 5 long and narrow, with anterior row of 21 and posterior row of 4 relatively short setae (Fig. 37D). Median lobe in lateral view slightly curved, with slightly thickened, angulate, and curved downwards apex; in ventral view, subparallel, with broad and slightly concave apex. Paramere slightly concave on dorsal side and with dense setae on subdistal part; proximal setae sparser (Fig. 37 A–C). Abdominal ventrite 6 with 3 or 4 lateral striae on each side.

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

Affinities.

Exocelina bewani sp. n. is very similar to E. sumokedi sp. n. but is larger and has a less striated abdominal ventrite 6; also, its median lobe is not narrowed distally in ventral view and with apex broad and slightly concave ventrally and curved downwards in lateral view. The species is also similar to E. adelbertensis sp. n., E. cyclops sp. n., E. pseudopusilla sp. n., and E. pusilla sp. n., see their “Affinities” and the “Key”.

Distribution.

Papua New Guinea: Sandaun Province. The species is known only from the type locality (Fig. 50).

Etymology.

The species is named after the Bewani Mountains. The name is a noun in the nominative singular standing in apposition.