Research Article |
Corresponding author: Helena Shaverdo ( shaverdo@mail.ru ) Academic editor: Mariano Michat
© 2020 Helena Shaverdo, Suriani Surbakti, Bob Sumoked, Michael Balke.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Shaverdo H, Surbakti S, Sumoked B, Balke M (2020) Two new species of the Exocelina ekari group from New Guinea with strongly modified male antennae (Coleoptera, Dytiscidae, Copelatinae). ZooKeys 960: 63-78. https://doi.org/10.3897/zookeys.960.55007
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Two new species of the genus Exocelina Broun, 1886: E. athesphatos sp. nov. and E. tsinga sp. nov. are described from New Guinea and placed into the E. ekari group based on the structure of their male genitalia. The two species are very similar with respect to their external morphology and characterised by almost identical, strongly modified male antennae. However, they can easily be separated by the shape and setation of the median lobe and paramere. Based on morphological similarity and results of a molecular phylogenetic analysis, we suggest these are sister species. Both of them have been collected on the southern slopes of the Central Range (the spine of New Guinea), with a distance of ca. 380 km straight line between the collecting localities.
Australasia, distribution, Exocelina, systematics, new species
Two new species of the genus Exocelina Broun, 1886 discovered on the southern slopes of the New Guinea Central Range are introduced. Having a discontinuous outline of the median lobe of the male genitalia, both belong to the largest Exocelina species group, E. ekari group. To date, this group contains 54 species (including the two new species) endemic to New Guinea (
The present work is based on material from the following collections:
KSP Koleksi Serangga Papua, at the Biology Department of Universitas Cenderawasih (UNCEN), Waena, Papua, Indonesia;
Our methods follow those described in detail in our previous articles (
Indonesia: Papua Province: Pegunungan Bintang Regency, near Ok Bap, 04°49'28.6"S, 140°24'47.0"E, 1,961 m a.s.l.
Holotype
: male “Indonesia: Papua, nr Ok Bab [sic!], 1961 m, 8.vi.2015, -4.82460033148527, 140.413050251081, Sumoked” (
Body size and form : Beetle medium-sized: TL-H 4.3–4.8 mm, TL 4.85–5.4 mm, MW 2.3–2.5 mm (holotype: TL-H 4.6 mm, TL 5 mm, MW 2.4 mm), with oblong-oval habitus.
Colouration
: Dorsally piceous, sometimes with dark brown posterior part of head, middle and lateral parts of pronotum, and usually with dark brown elytral sutural lines; head appendages yellowish red, legs yellowish red to reddish brown (Fig.
Surface sculpture : Shiny dorsally, with inconspicuous to fine, distinct punctation and weakly impressed microreticulation. Head with dense punctation (spaces between punctures 1–2 times size of punctures), evidently finer and sparser anteriorly; diameter of punctures almost equal to diameter of cells of microreticulation. Pronotum with sparser and finer punctation than head. Elytra with very sparse and fine punctation, sometimes inconspicuous. Microreticulation of elytra weakly impressed, in some specimens slightly stronger. Pronotum and especially head with stronger microreticulation. Metaventrite and metacoxae distinctly microreticulate, metacoxal plates with longitudinal strioles and transverse wrinkles. Abdominal ventrites with distinct microreticulation, strioles, and very fine and sparse punctation.
Structures : Pronotum with distinct, relatively narrow lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct lateral bead and few setae. Abdominal ventrite 6 broadly rounded or almost truncate, with elongate medial impression.
Male
: Antenna strongly modified (Figs
Female : Antennae and pro- and mesotarsi not modified. Abdominal ventrite 6 more rounded apically, with shallow elongate medial impression, without tubercles and lateral striae.
Based on shape of the modified male antennae and presence of pronotal bead, the new species can be placed close to the E. polita species complex in the identification key. However, this is not a monophyletic group. According to a molecular phylogenetic analysis (Toussaint et al., in preparation), the two new species are sister species, on their own separate branch within the E. ekari group.
Exocelina athesphatos sp. nov. is similar to E. utowaensis Shaverdo, Hendrich & Balke, 2012 in modifications of the abdominal ventrite 6 and general shape of the median lobe and paramere. But the new species distinctly differs from it in larger size (TL-H 3.4–3.8 mm in E. utowaensis), having pronotal bead (absent in E. utowaensis) and strongly modified male antennae (simple in E. utowaensis). Additionally, in general shape of the median lobe and paramere as well as in the relatively narrow pronotal bead, the new species resembles E. oceai Shaverdo, Hendrich & Balke, 2012, which is, however, much smaller (TL-H 3.35–3.8 mm) and has simple male antennae. For comparison with E. tsinga sp. nov. see below.
Indonesia: Papua Province. The species is known only from the type locality.
The species name αθέσφατος derives from Greek, meaning “unadulterated, pure”. The name is an adjective in the nominative singular.
Indonesia: Papua Province, Mimika Regency, Tsinga Village, Tsingogong River, 04°11.320'S, 137°16.364'E, 1,306 m a.s.l.
Holotype
: male “Indonesia: Kabupaten [Regency] Mimika, Desa [Village] Tsinga, Sungai [River] Tsingogong”, “1306 m, 25–30.v.2017, 04°11.320'S, 137°16.364'E, B. Sumoked” (
Body size and form
: Beetle medium-sized: TL-H 4.05–4.8 mm, TL 4.5–5.3 mm, MW 2.15–2.5 mm (holotype: TL-H 4.5 mm, TL 5 mm, MW 2.4 mm), with oblong-oval to elongate habitus (Fig.
Colouration : As in E. athesphatos sp. nov.
Surface sculpture : As in E. athesphatos sp. nov.
Structures : Pronotum with distinct, relatively narrow anteriorly lateral bead. Base of prosternum and neck of prosternal process with distinct ridge, slightly rounded anteriorly. Blade of prosternal process lanceolate, relatively broad, slightly convex, with distinct lateral bead and few setae. Abdominal ventrite 6 broadly rounded or slightly truncate.
Male
: Antenna strongly modified (Figs
Female : Antennae and pro- and mesotarsi not modified. Abdominal ventrite 6 without depression and lateral striae.
About the placement within the E. ekari group, we consider the species in the same way as E. athesphatos sp. nov. Both species are very similar in external morphology (colouration, body form and sculpture, shape of male antennae) and, therefore, difficult to distinguish without detailed study (Figs
Indonesia: Papua Province, Mimika Regency. The species is known only from the type locality.
The species is named after Tsinga Village. The name is a noun in the nominative singular standing in apposition.
We are grateful to Dr H. Schillhammer (Vienna) for the photographs. Specimens were loaned from
Financial support for the study was provided by the FWF (Fonds zur Förderung der wissenschaftlichen Forschung – the Austrian Science Fund) through the projects P 24312-B17 and P 31347-B25 to Helena Shaverdo. Michael Balke was supported by the German Science Foundation (DFG BA2152/11-1, 11-2, 19-1, 19-2).