Exocelina okapa 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 : 29

15. Exocelina okapa Shaverdo & Balke sp. n. Figs 23, 47

Type locality.

Papua New Guinea: Eastern Highlands Province, Wapi Creek, Kimiagomo, Okapa, 06°25.41'S, 145°34.48'E, 1900 m a.s.l.

Type material.

Holotype: male "Papua New Guinea: Eastern Highlands, Wapi Creek, Kimiagomo, Okapa, 1900m, 9.viii.2005, 6 25.407S 145 34.480E, K.Sagata (WB122)" (ZSM). Paratypes: 5 males, 2 females with the same label as the holotype (NHMW, ZSM). 1 male, 3 females "Papua New Guinea: Eastern Highlands, Tegupate creek Kimiagomo, Okapa, 1900m, 9.viii.2005, 6 25.407S 145 34.480E, K.Sagata (WB124)" (NHMW, ZSM). 1 male, 2 females "Papua New Guinea: Eastern Highlands, Kimiagomo vill, north Okapa stn, 1900, 30.iv.2006, 06.25.407S 145.34.480E, Sagata (PNG 80)" (NHMW, ZSM). 1 male, 4 females "Papua New Guinea: Eastern Highlands, Yuyulio, Kimiagomo-Okapa, 2100m, 13.iv.2003, 06 25.255S 145 34.233E, K. Sagata (WB7)" (NHMW, ZSM). 1 male "Papua New Guinea: Eastern Highlands, Kainantu, Yoginofi, 1900m, 9.v.1994, 06.21.799S 145.45.463E, Balke & Sagata (PNG 55)" (ZSM).

Additional material.

3 females "Papua New Guinea: Eastern Highlands, Hano kotu, Kimiagomo, Okapa, 1661m, 11.viii.2006, 06 25.096S 145 34.556E, K.Sagata (WB129)" (ZSM).

Description.

Body size and form: Beetle medium-sized: TL-H 3.95-4.7 mm, TL 4.3-5.05 mm, MW 2.05-2.5 mm (holotype: TL-H 4.3 mm, TL 4.7 mm, MW 2.3 mm), with oblong-oval habitus, slightly more attenuated posteriorly.

Coloration: Piceous, with reddish brown pronotum. Head reddish brown to piceous, paler anteriorly and darker posterior to eyes. Pronotum dark brown to piceous, with reddish to reddish brown sides narrowly or broadly. Elytra dark brown to piceous, sometime with narrow reddish sutural lines. Head appendages and legs proximally yellowish red, legs distally darker, reddish brown, especially metathoracic legs (Fig. 23). Teneral specimens paler.

Surface sculpture: Shiny dorsally. Head mostly with fine, sparse punctation (spaces between punctures 2-3 times size of punctures) but punctation denser and coarser between eyes; diameter of punctures smaller than diameter of cells of microreticulation. Pronotum and elytra with very fine, sparse punctation, sometimes inconspicuous on elytra. Pronotum and elytra with weakly 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 very fine, sparse, often inconspicuous 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, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively narrow, slightly convex, and smooth, with distinct lateral bead and few lateral setae. Abdominal ventrite 6 rounded.

Male: Antennae simple (Fig. 23). Protarsomere 4 with large, thick, strongly curved anterolateral hook-like seta. Protarsomere 5 ventrally with anterior band of ca 60 and posterior row of 20 relatively long, thin setae (Fig. 47D). Median lobe in lateral view slightly curved, with apex dully pointed, slightly bent downwards; in ventral view, broadened subdistally, with broad, rounded apex. Paramere slightly concave on dorsal side and with dense setae on subdistal part; proximal setae inconspicuous (Fig. 47 A–C). Abdominal ventrite 6 with 8-12 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 okapa sp. n. is similar to E. yoginofi sp. n. but differs from it in very weak dorsal punctation and microreticulation and more slender median lobe. The species is also similar to E. mendiensis sp. n. but differs from it in distinctly smaller size and differently shaped apex of the median lobe.

Distribution.

Papua New Guinea: Eastern Highlands Province (Fig. 50).

Etymology.

The species is named after Okapa Station. The name is a noun in the nominative singular standing in apposition.