Exocelina posmani Shaverdo & Balke

Shaverdo, Helena, Sagata, Katayo & Balke, Michael, 2016, Taxonomic revision of New Guinea diving beetles of the Exocelinadanae group, with the description of ten new species (Coleoptera, Dytiscidae, Copelatinae), ZooKeys 619, pp. 45-102 : 69-72

Taxon classification Animalia Coleoptera Dytiscidae

12. Exocelina posmani Shaverdo & Balke sp. n. Figs 23, 38

Exocelina undescribed sp. MB3406: Toussaint et al. 2014: supplementary figs 1-4, tab. 2.

Type locality.

Papua New Guinea: Central Province, Myola, 09°08.05'S; 147°42.24'E, 1760 m a.s.l.

Type material.

Holotype: male "Papua New Guinea: Central, Myola, 1760m, i.2008, [09°] 08.052S 147 42.241E, Posman (PNG 176)" (ZSM). Paratypes: 2 males, 4 females with the same label as the holotype, one male with an additional green label "DNA M.Balke 3406" (NHMW, ZSM). 1 male, 1 female "Papua New Guinea: Central, Woitape, 1700m, i.2008, [08°] 31.290S 147 13.684'E, Posman (PNG 166)" (ZSM). 2 males "Papua New Guinea: Central, Woitape, 1500m, i.2008, [08°] 33.178S 147 15.481E, Posman (PNG 167)" (NHMW, ZSM). 4 males, 2 females "Papua New Guinea: Central, Kokoda Trek, 1400m, i.2008, [09°] 14.339S 147 40.538E, Posman (PNG 171)" (NHMW, ZSM). 1 female "Papua New Guinea: Central, Kokoda Trek, 1400m, i.2008, [09°] 01.952S 147 44.455E, Posman (PNG 172)" (ZSM).

Diagnosis.

Beetle medium-sized, piceous, with paler head and sides of pronotum; dorsal surface with fine punctation and evident microreticulation, shiny; pronotum with distinct lateral bead; male antennomeres simple; protarsomere 4 with weakly curved anterolateral hook-like seta, equal to more laterally situated large seta; median lobe only slightly broadened in distal part, with almost parallel sides and slightly concave apex in ventral view, with slightly curved, broad, rounded apex in lateral view, on both lateral sides with numerous fine setae situated not linearly but on large area of anterior half of distal part of median lobe under short fine carina; paramere without notch on dorsal side. The species is similar to Exocelina marawaka sp. n. but differs from it in the structure of the median lobe: apex shorter and broader in lateral view and slightly concave in ventral view, distal setae arranged into one area, not situated linearly. This species was collected together with of Exocelina woitapensis sp. n., which is smaller and matt, with stronger punctation and microreticulation of the dorsal surface.

Description.

Size and shape: Beetle medium-sized (TL-H 3.65-4.4 mm, TL 4-4.5 mm, MW 1.95-2.2 mm), with oblong-oval habitus, broadest at elytral middle. Coloration: Head uniformly dark brown to piceous or reddish-brown to brown, dark brown behind eyes and on middle; pronotum dark brown to piceous, paler on sides; elytra uniformly dark brown to piceous, seldom with narrow reddish sutural lines; ventrally reddish-brown; head appendages and legs proximally yellowish red, legs distally darker, reddish brown (Fig. 38).

Surface sculpture: As in Exocelina marawaka sp. n.

Structures: Pronotum with distinct lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, not rounded anteriorly, without anterolateral extensions. Blade of prosternal process lanceolate, relatively narrow, convex, with distinct bead and few setae laterally; neck and blade of prosternal process evenly jointed. Abdominal ventrite 6 broadly rounded.

Male: Antenna simple. Protarsomere 4 with small (equal to more laterally situated large seta), weakly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of 22 setae and posterior row of 5 short setae (Fig. 23A). Abdominal ventrite 6 with 4-7 lateral striae on each side. Median lobe only slightly broadened in distal part, with almost parallel sides and slightly concave apex in ventral view, with slightly curved, broad, rounded apex in lateral view, on both lateral sides with numerous fine setae situated not linearly but on large area of anterior half of distal part of median lobe under short, fine carina (Fig. 23 B–C). Paramere without notch, slightly concave on dorsal side, with thin, sparse, inconspicuous proximal setae and thicker, denser, and longer subdistal setae (Fig. 23D).

Holotype: TL-H 3.9 mm, TL 4.35 mm, MW 2.15 mm.

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

Variability.

Elytral punctation varies from inconspicuous to distinct.

Distribution.

Papua New Guinea: Central Province (Fig. 40).

Etymology.

The species is named for Aloysius Posman. The species name is a noun in the genitive case.