Exocelina keki 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 : 22-24

10. Exocelina keki Shaverdo & Balke sp. n. Figs 6, 30

Exocelina undescribed sp. MB1530: Toussaint et al. 2014: supplementary figs 1-4, table 2; Toussaint et al. 2015: supplementary figs S1-S2, table S3.

Exocelina pseudokeki _New_Guinea_MB1530: Toussaint et al. 2015: supplementary information S5-S6.

Type locality.

Papua New Guinea: Madang, Adelbert Mts, creek near Keki, 04°42.30'S, 145°25.09'E, 790 m a.s.l.

Type material.

Holotype: male "Papua New Guinea: Madang, Keki, Adalbert [sic!] Mts., 500m, 29.xi.2006, nr 04.43.058S 145.24.437E, Balke & Kinibel (PNG 118)" (ZSM). Paratypes: Madang: 9 males, 4 females with the same labels as the holotype, one male with an additional green label "M.Balke 1530" (NHMW, ZSM). 1 male, 3 females "Papua New Guinea: Madang, Adalbert [sic!] Mts., creek nr Keki, 790m, 28.xi.1994, 04.42.300S 145.25.089E, Binatang Boys leg. (PNG 53a)" (ZSM). 1 male, 2 females "Papua New Guinea: Madang, Keki-Sewan, Adalbert [sic!] Mts., 700m, 30.xi.2006, nr 04.41.802S 145.25.460E, Binatang Boys (PNG 120)" (ZSM). Eastern Highlands: 1 male "Papua New Guinea: Eastern Highlands, Bena Bridge, 1400m, 8.xii.2007, 06.10.781S 145.26.034E, Balke & Sagata (PNG 164)" (ZSM).

Description.

Body size and form: Beetle small: TL-H 3.15-3.65 mm, TL 3.45-4.0 mm, MW 1.65-1.9 mm (holotype: TL-H 3.65 mm, TL 4 mm, MW 1.85 mm), with oblong habitus.

Coloration: Reddish to reddish brown, with head and pronotum paler. Head yellowish red to reddish brown, with small darker areas posterior to eyes. Pronotum yellowish red to reddish brown, with small brown to dark brown area on disc. Elytra reddish brown to brown, with narrow reddish sutural lines. Head appendages yellowish red, legs reddish, distally darker, especially metathoracic legs (Fig. 6). Teneral specimens paler.

Surface sculpture: Submatt dorsally. Head with rather dense punctation (spaces between punctures 1-2 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum and elytra with dense, distinct but fine 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, strioles, and very fine sparse punctation.

Structures: Pronotum without lateral bead, in few specimens with its traces in posterior part. Base of prosternum and neck of prosternal process with distinct ridge, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively narrow, slightly convex, with distinct lateral bead and few setae. Abdominal ventrite 6 rounded.

Male: Antennae simple (Fig. 6). Protarsomere 4 with anterolateral seta thin, long, smaller than more laterally situated large setae, slightly curved downwards. Protarsomere 5 long and narrow, with anterior band of more than 40 and posterior row of 7 relatively long, thin setae (Fig. 30D). Median lobe in lateral view almost straight, its apex rounded and not curved downwards; in ventral view, distally distinctly narrowed before rounded, narrow apex. Paramere slightly concave on dorsal side and with dorsal setae distinctly divided to long, dense subdistal setae and sparser proximal ones (Fig. 30 A–C). Abdominal ventrite 6 with 3-5 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.

Distribution and variability.

Papua New Guinea: Madang and Eastern Highlands (Fig. 50). The species is known mainly from Keki area in Adelbert Mountains; only one beetle was collected in Bena, Eastern Highlands. It shows no morphological difference from the specimens of Keki populations, except for a small difference in the median lobe shape, which could be an expression of species variability. The species might have the same pattern of distribution as Exocelina brahminensis Shaverdo et al., 2012, which has a wide distribution in the Momase Region and is known from Adelbert Mountains and Bena.

Affinities.

Exocelina keki sp. n. is very similar to Exocelina messeri (Balke, 1999) in body form and coloration, but has much more distinct dorsal punctation and stronger microreticulation, as well as median lobe more slender, with apex smaller and narrower in ventral view; the ventral setae of male protarsomere 5 are much less numerous and clearly divided into anterior band and posterior row.

Etymology. The

species is named after Keki Village. The name is a noun in the nominative singular standing in apposition.