Exocelina pulchella Shaverdo & Balke

Shaverdo, Helena, Surbakti, Suriani, Warikar, Evie L., Sagata, Katayo & Balke, Michael, 2019, Nine new species groups, 15 new species, and one new subspecies of New Guinea diving beetles of the genus Exocelina Broun, 1886 (Coleoptera, Dytiscidae, Copelatinae), ZooKeys 878, pp. 73-143 : 73

21. Exocelina pulchella Shaverdo & Balke sp. nov. Figs 47 , 51

Exocelina undescribed sp. MB3408: Toussaint et al. 2014: supplementary figs 1-4, tab. 2; Toussaint et al. 2015: supplementary figs S1, S2, tab. S3, and information S5, S6.

Type locality.

Papua New Guinea: Central Province, Moroka, Kailaki, Wareaga, 09°25.42'S, 147°31.07'E, 760 m a.s.l.

Type material.

Holotype: male "Papua New Guinea Central, Moroka, Kailaki Wareaga, 760m, 27x2009 9.25.424S 147.31.068E Sagata (PNG227)" (ZSM). Paratypes: 24 males, 43 females with the same label as the holotype, one male with an additional green label "DNA M.Balke 3832" (NHMW, ZSM). 1 male "Papua New Guinea: Central, Moroka area, Kailaki, 827 m, 26.x.2009, 9.24.134S 147.33.521E, Sagata (PNG225)" (ZSM). 5 males, 9 females "Papua New Guinea: Central, 755m, 28.x.2009 S9 25 47 5 E147 32 59.1, Sagata (PNG229)", one male with an additional green label "DNA M.Balke 3831" (NHMW, ZSM). 2 males, 1 female "Papua New Guinea: Central, Kokoda Trek, 320m, i.2008 09 19.236S 147.31.791E, Posman (PNG 168)", one male with a green label "DNA M.Balke 3403" (ZSM). 2 males, 2 females "Papua New Guinea: Central, Kokoda Trek, 980m, i.2008, 09 15.933S 147.36.590E, Posman (PNG 169)" (NHMW, ZSM). 1 female "Papua New Guinea: Central, Kokoda Trek, 590m, i.2008, 09 14.339S 147.36.920E, Posman (PNG 170)" (ZSM). 3 males "Papua New Guinea: Central, Myola, 1110m, i.2008, 09 12.630S 147.31.880E, Posman (PNG 177)", one of them with an additional green label "DNA M.Balke 3408" (ZSM).

Description.

Body size and form: Beetle small: TL-H 2.85-3.3 mm, TL 3.15-3.7 mm, MW 1.6-1.8 mm (holotype: TL-H 3.05 mm, TL 3.4 mm, MW 1.75 mm), with oblong-oval habitus.

Colouration: Reddish head and bicoloured elytra: yellowish at shoulders and brownish distally. Head reddish, reddish brown posterior eyes. Pronotum reddish brown to brown on disc (broader or narrower) and yellowish to yellowish reddish on sides. Elytra bicoloured: yellowish in proximal 1/4 to 1/3 (rarely to 1/2) and yellowish brown to brown distally, proximal yellowish colouration sometimes more distinctly boarded as shoulder spots slightly elongated along sutural lines, but mostly fuzzy, not boarded. Head appendages and legs proximally yellowish, legs distally darker, reddish to reddish brown ( Fig. 47 ). Teneral specimens paler.

Surface sculpture: Shiny dorsally, with extremely fine and sparse punctation and weakly impressed microreticulation. Head with fine and sparse punctation (spaces between punctures 2-3 times size of punctures); diameter of punctures smaller than diameter of cells of microreticulation. Pronotum with much finer and sparser punctation than on head, very inconspicuous. Punctation on elytra invisible. Pronotum and elytra with weakly impressed microreticulation; head with microreticulation slightly stronger. Metaventrite, metacoxae, and abdominal ventrites distinctly microreticulate. Metacoxal plates with longitudinal strioles and weak transverse wrinkles; abdominal ventrites with strioles. Punctation on venter invisible; inconspicuous on two last abdominal ventrites.

Structures: Pronotum with lateral bead. 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 bead and few setae laterally. Abdominal ventrite 6 broadly rounded or slightly truncate.

Male: Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band ca. 60 and posterior row of eight relatively long setae ( Fig. 51D ). Abdominal ventrite 6 with 4-7 lateral striae on each side. Median lobe simple, short, slightly curved, with broadly pointed apex in lateral view, and evenly tapering to broadly pointed apex in ventral view ( Fig. 51A, B ). Paramere slightly concave on dorsal side, with strong, long, dense subdistal setae, proximal setae inconspicuous ( Fig. 51C ).

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

Affinities.

From species of the E. danae , E. bacchusi and E. jaseminae groups (Shaverdo et al. 2016d) known from Central Province, E. pulchella sp. nov. can be easily distinguished by its small size, characteristic colouration, extremely fine dorsal punctation, and shape of the median lobe. For the affinities within the group, see the “Key”.

Distribution.

Papua New Guinea: Central Province ( Fig. 54 ).

Etymology.

The species name derives from Latin pulchellus, a diminutive of pulcher (beautiful), to express the small size and nice colouration of the beetles; this species is the most colourful of all known New Guinea Exocelina . The species name is an adjective in the nominative singular.

Figures

Figure 54. Map of the eastern part of New Guinea showing distribution of the species of the E. warasera group.

Figures 46 - 49. Habitus and colouration 46 Exocelina kobau sp. nov. 47 E. pulchella sp. nov. 48 E. warasera sp. nov. 49 E. haia sp. nov.

Figures 50, 51. 50 Exocelina kobau sp. nov. 51 E. pulchella sp. nov. A median lobe in ventral view B median lobe in lateral view C paramere in external view D male protarsomeres 4 - 5 in ventral view.