Exocelina ibalimi 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 : 21-22

9. Exocelina ibalimi Shaverdo & Balke sp. n. Figs 4, 28

Exocelina undescribed sp. MB0657: Toussaint et al. 2014: supplementary figs 1-4, table 2; Toussaint et al. 2015: supplementary figs S1-S2, table S3.

Exocelina ibalimi _New_Guinea_MB0657: Toussaint et al. 2015: Supplementary information S5-S6.

Type locality.

Papua New Guinea: Sandaun Province, Mianmin area, ca 04°55.78'S, 141°38.18'E, 1080 m a.s.l.

Type material.

Holotype: male "Papua New Guinea: Sandaun, Mianmin area,>600m, 13.i.2010, Ibalim & Pius (PNG235)" (ZSM). Paratypes: 15 males, 14 females with the same label as the holotype, 2 males with additional labels "M.Balke 4929", "M.Balke 4932", and one female with "M.Balke 4930" (NHMW, ZSM). 4 males, 1 female "Papua New Guinea: Sandaun, Ofektaman, 820m, 17.x.2008, 5.04.113S 141.35.841E, Ibalim (PNG 190)", two males additionally with green labels "M.Balke 3724", "M.Balke 3725" (NHMW, ZSM). 3 females "Papua New Guinea: Sandaun, Mianmin, 670m 20.x.2008, 4.53.292S 141.34.118E, Ibalim (PNG 191)" (ZSM). 2 males "Papua New Guinea: Sandaun, Mianmin (river), 990m, 23.x.2008, 4.54.570S 141.35.490E, Ibalim (PNG 192)" (ZSM). 3 males "Papua New Guinea: Sandaun, Mianmin (pool), 990m, 23.x.2008, 4.54.570S 141.35.490E, Ibalim (PNG 193)", two of them with additional green labels "M.Balke 3739", "M.Balke 3740" (ZSM). 4 males, 4 females "Papua New Guinea: Sandaun, Mianmin (river), 1080m, 24.x.2008, 04.55.780S 141.38.185E, Ibalim (PNG 195)" (NHMW, ZSM). 6 males, 12 females "Papua New Guinea: Sandaun, Mianmin (pool), 1080m, 24.x.2008, 04.55.780S 141.38.185E, Ibalim (PNG 196)" (ZSM). 2 males, 1 female "Papua New Guinea: Sandaun, Mianmin (river) 700m, 21.x.2008, 04.52.858S 141.31.706E Ibalim (PNG 197)" (ZSM). 5 males, 3 females "Papua New Guinea: Sandaun, Mianmin (pool), 700m, 21.x.2008, 04.52.858S 141.31.706E, Ibalim (PNG 198)" (NHMW, ZSM). 2 males "Papua New Guinea: Sandaun, Mianmin area,>1000m, 23.xii.2009, Ibalim & Pius (PNG232)" (ZSM). 4 males, 1 female "Papua New Guinea: Sandaun, Mianmin area,>1000m, 26.xii.2009, Ibalim & Pius (PNG233)" (NHMW, ZSM). 8 males, 3 females "Papua New Guinea: Sandaun, Mianmin area,>600m, 13.i.2010, Ibalim & Pius (PNG236)", one of them with "M.Balke 4925" (NHMW, ZSM). 5 males, 8 females "Papua New Guinea: Sandaun, Mianmin area,>700m, 14.i.2010, 0 4 54.540S 141 36.953E, Ibalim & Pius (PNG238)" (NHMW, ZSM). 1 male "Papua New Guinea: Sandaun, Mianmin 2, 1150 m, 20.x.2003, 04 52.562S 141 37.038E, K. Sagata (WB70)", "M. Balke 658" [green text] (ZSM). 2 males "Papua New Guinea: Sandaun, MekilK [!], 1718m, 14.x.2003, 4 48.742S 141 39.075E, K. Sagata (WB106)", one of them with "M. Balke 661" [green text] (ZSM). 1 male "Papua New Guinea: Sandaun: Mekil (WB106), 14.x.2003, K. Sagata, M Balke: MB 660", "M. Balke 660" [green text] (ZSM). 1 female "Papua New Guinea: Sandaun, Sokamin village, 1200m, 9.x.2003, 4 51.883S 141 37.534E, K. Sagata (WB97)", "M. Balke 657" [green text] (ZSM). 2 males, 1 female "Papua New Guinea: Sandaun, Sokamin4, 1200m, 19.x.2003, 4 50.845S 141 37.865E, K. Sagata (WB100)", males with green text labels "M. Balke 683" and "M. Balke 684" (ZSM).

Description.

Body size and form: Beetle size variable but generally beetle medium-sized: TL-H 3.45-4.3 mm, TL 3.75-4.8 mm, MW 1.8-2.25 mm (holotype: TL-H 4.15 mm, TL 3.75 mm, MW 2 mm), with oblong-oval habitus, slightly more attenuated posteriorly.

Coloration: Brown to piceous, with head and pronotum paler. Head reddish brown to piceous, darker posteriorly. pronotum reddish brown to piceous, broadly paler on lateral sides and sometimes also narrowly anteriorly and posteriorly. Elytra uniformly brown to piceous. Head appendages and legs yellowish red to reddish brown, legs distally darker, especially metathoracic legs (Fig. 4). 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 fine but rather dense 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. Base of prosternum and neck of prosternal process with distinct ridge, rounded anteriorly. Blade of prosternal process lanceolate, relatively narrow, slightly convex, with distinct lateral bead and few setae. Abdominal ventrite 6 broadly rounded or slightly truncate.

Male: Antennae simple (Fig. 4). Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 long and narrow, with anterior band of more than 80 and posterior row of 11 relatively long, thin setae (Fig. 28D). Median lobe in lateral view slightly curved, its apex rounded and not or only very slightly curved downwards; in ventral view, distally distinctly narrowed to truncate apex. Paramere slightly concave on dorsal side and with long, dense, thin setae situated along dorsal margin: subdistal setae denser, proximal setae sparser, setae in middle shorter, thinner (Fig. 28 A–C). Abdominal ventrite 6 with 7-11 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.

Variability.

The species has variability in size, coloration and shape of the median lobe. Beetles are small to medium-sized (see the measurements above) and with coloration: from reddish head and pronotum and dark brown elytra to uniformly piceous with reddish brown pronotal sides. Median lobe shows different shape of its apex: in lateral view, it is not curved or differently slightly curved downwards reminding that of E. fume but without distinct angle.

Affinities.

Exocelina ibalimi sp. n. is very similar to E. fume but differs from it in shape of the median lobe: its apex not curved or only slightly curved downwards, more or less rounded in lateral view, without distinct angle on the dorsal side. The species also has dorsal punctation distinctly finer and microreticulation less strongly impressed than in E. fume .

Distribution.

Papua New Guinea: Sandaun Province (Fig. 50).

Etymology.

The species is named for Sentiko Ibalim, one of the great young PNG entomologists, who collected most of these beetles. The species name is a noun in the genitive case.