Exocelina ambua 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 : 11-13

2. Exocelina ambua Shaverdo & Balke sp. n. Figs 21, 45

Exocelina undescribed sp. MB1290: Toussaint et al. 2014: supplementary figs 1-4, table 2; Toussaint et al. 2015: supplementary figs S1-S2, table S3.

Exocelina ambuaensis _New_Guinea_MB1290: Toussaint et al. 2015: supplementary information S5-S6.

Type locality.

Papua New Guinea: Southern Highlands Province, Tari, Mt Ambua, 05°57.55'S, 143°04.99'E, 2,100 m a.s.l.

Type material.

Holotype: male "Papua New Guinea: Southern Highlands, Tari, Mt Ambua, 2100m, 14.v.2006, 05.57.550S 143.04.993E, Balke (PNG 64)" (ZSM). Paratypes: 3 males, 2 females with the same label as the holotype, one of the males with an additional green label "M.Balke 1290" (NHMW, ZSM).

Description.

Body size and form: Beetle medium-sized: TL-H 4.3-4.7 mm, TL 4.8-5.2 mm, MW 2.2-2.5 mm (holotype: TL-H 4.4 mm, TL 4.8 mm, MW 2.3 mm), with oblong habitus.

Coloration: Brown to piceous, with head and pronotum paler. Head reddish brown to piceous, with small darker areas posterior to eyes. Pronotum dark brown to piceous, paler on sides and darker on disc. Elytra dark brown to piceous, with vague narrow reddish to brownish sutural lines. Head appendages and legs proximally reddish brown, legs distally darker, brownish, especially metathoracic legs (Fig. 21).

Surface sculpture: Matt dorsally. Head with dense, coarse punctation (no spaces between punctures or spaces 2 times size of punctures), finer and sparser anteriorly; diameter of punctures equal to diameter of cells of microreticulation. Pronotum and elytra with dense, coarse punctation, sparser and finer than on head. Pronotum and elytra with 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 and strioles. Metaventrite medially, metacoxal plates, and abdominal ventrites with fine, sparse punctation.

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

Male: Antennae simple (Fig. 21). Protarsomere 4 with anterior angle slightly expanded, with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 slightly concave ventrally, with anterior band of ca 70 and posterior band of ca 30 relatively long setae (Fig. 45D). Median lobe in lateral view short, slightly curved, and evenly tapering to dully pointed apex, apex not bent downwards; in ventral view, almost subparallel and distally slightly narrowed to apex, apex roundly truncate. Paramere slightly concave on dorsal side, with long, dense subdistal setae, proximal ones finer (Fig. 45 A–C). Abdominal ventrite 6 with 13-15 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 ambua sp. n. is similar to E. mendiensis sp. n. but differs from it in smaller size, coarser and denser dorsal punctation and microreticulation, and shape of the median lobe.

Distribution.

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

Etymology.

The species is named after Mt Ambua. The name is a noun in the nominative singular standing in apposition.