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Seven new species of Trigonopterus Fauvel (Coleoptera, Curculionidae) from the Tanimbar Archipelago
expand article infoRaden Pramesa Narakusumo§, Michael Balke|, Alexander Riedel
‡ State Museum of Natural History Karlsruhe, Karlsruhe, Germany
§ Indonesian Institute of Sciences, Cibinong, Indonesia
| SNSB-Zoological State Collection, Munich, Germany
¶ Natural History Museum Karlsruhe, Karlsruhe, Germany
Open Access

Abstract

Based on recent fieldwork, the hyperdiverse weevil genus Trigonopterus Fauvel is recorded for the first time from the Indonesian Tanimbar Archipelago, halfway between Australia and Western New Guinea. All seven species discovered on Tanimbar are new to science, and described here: Trigonopterus atuf sp. nov., T. kumbang sp. nov., T. laratensis sp. nov., T. porg sp. nov., T. selaruensis sp. nov., T. tanimbarensis sp. nov., and T. triradiatus sp. nov. The new species are authored by the taxonomists-in-charge, Raden Pramesa Narakusumo and Alexander Riedel. This fauna appears discordant and established by relatively recent dispersal from New Guinea and other Moluccan islands.

Keywords

Coleoptera, conservation, cox1, Cryptorhynchinae, DNA barcoding, endemism, hyperdiverse, integrative taxonomy, Moluccas, morphology, Southeast Asia, Tanimbar, turbo-taxonomy, Wallacea, weevils.

Introduction

Trigonopterus Fauvel is a genus of hidden snout weevils (Cryptorhynchinae) (Alonso-Zarazaga and Lyal 1999; Riedel et al. 2016). These beetles are flightless, yet the 444 species currently known cover a large geographic area, across the Indo-Australian Archipelago and into Oceania (Riedel et al. 2010, 2014; Riedel and Tänzler 2016; van Dam et al. 2016). Hundreds of additional species await discovery (Riedel et al. 2013b, 2014; Riedel and Tänzler 2016; Riedel and Narakusumo 2019; https://species-id.net/wiki/Trigonopterus; unpublished data). New Guinea is the center of Trigonopterus diversity (Tänzler et al. 2012, 2016, 2017).

The relatively rich Trigonopterus faunas of Sulawesi and Sundaland originated by dispersal from New Guinea and subsequent diversification (Tänzler et al. 2016). The fauna of the Moluccan Islands may have served as stepping stones, yet little is known about these islands. There is only one described species from Seram Island, i.e., Trigonopterus ellipticus (Pascoe) (Riedel 2011), though several undescribed species from Halmahera and Ternate Islands were included in the phylogeny of the genus published by Tänzler et al. (2016).

Here, we present the results of a recent survey of the Tanimbar Archipelago, or simply Tanimbar. Tanimbar is a cluster of islands located approximately halfway between Australia in the south (Darwin area, ca. 320 km distant) and Western New Guinea in the north (ca. 340 km). The island of Timor is ca. 380 km to the west, and the Kai and Aru Islands lie ca. 150 km and 240 km, respectively, to the northeast. The Tanimbar Islands are all low, i.e., below an elevation of 300 meters. The climate is relatively seasonal, and forest cover comprises of seasonal evergreen forest, dry deciduous forest and moist deciduous forest (Laumonier and Nasi 2018). Geologically, Tanimbar belongs to the outer non-volcanic Banda arc formed in the Quaternary (Hall 1998, 2002). Parts of the islands are covered with early Pleistocene marine deposits and quaternary reefs occur up to 200 m in altitude (De Smet et al. 1989; Charlton et al. 1991), indicating a very recent origin of ca. 1 Ma. During the Pleistocene, the Tanimbar Islands remained insular as they are not connected to the Sahul shelf (Voris 2000). Thus, Tanimbar has been used as a geological calibration point for a phylogenetic analysis of passerine birds (Jønsson et al. 2010).

Here we describe seven new species of Trigonopterus from Yamdena, Larat, and Selaru islands, the three biggest islands of the Tanimbar Archipelago. We follow the “fast-track” taxonomy approach that combines molecular and morphological systematics (Riedel et al. 2013a, b), including data release on open access websites, i.e., species-ID (https://species-id.net/wiki/Trigonopterus) and wikispecies (https://species.wikimedia.org/wiki/Trigonopterus).

Materials and methods

This study is based on 222 specimens of Trigonopterus collected on two field trips to the Tanimbar Islands by the first author. Specimens were collected by beating foliage in primary forest. Holotypes were selected from 44 DNA sequenced specimens. DNA was extracted nondestructively as described by Riedel et al. (2010), with proteinase K lysis so that the genitalia of most specimens did not require extra maceration after DNA-extraction and could be directly stained with an alcoholic Chlorazol Black solution and stored in glycerol in microvials attached to the pin of the specimens. Genitalia of collection specimens or specimens whose abdominal muscle tissue was not sufficiently digested after DNA extraction were macerated in a 10% KOH solution and rinsed in diluted acetic acid before staining. Illustrations of habitus and genitalia were prepared from holotypes. Finally, type series were supplemented with specimens stored in ethanol and older material from the dry collection. Type depositories are cited using the following codens:

MZB LIPI Research Center of Biology, Division of Zoology, Museum Zoologicum Bogoriense, Widyasatwaloka, Cibinong, Indonesia;

SMNK Staatliches Museum für Naturkunde, Karlsruhe, Germany;

ZSM Zoologische Staatssammlung München, Germany.

The methods applied for DNA sequencing and sequence analysis are described by Riedel et al. (2010) and Tänzler et al. (2012). Morphological descriptions are limited to major diagnostic characters as outlined by Riedel et al. (2013a, b). Negative character states (i.e., the absence of a character) are only mentioned explicitly where it appears appropriate. In groups comprising hundreds of species enumerating the absence of rare character states leads to inflated descriptions that distract the reader from the important information, i.e., the diagnostic characters present in a given species.

The closest relatives of Tanimbar species were identified by creating an alignment of 1.154 cox1 sequences representing ca. 1000 species and generating a maximum likelihood reconstruction using the program IQTREE (Nguyen et al. 2015, Trifinopoulos et al. 2016). Morphological terminology follows Beutel and Leschen (2005) and Leschen et al. (2009), i.e., the terms “mesoventrite” / “metaventrite” are used instead of “mesosternite” / “metasternite” and “mesanepisternum” / “metanepisternum” instead of “mesepisternum” / “metepisternum”; “penis” is used instead of “aedeagus” as the tegmen is usually without useful characters in Trigonopterus and therefore omitted from species descriptions. Specimens were examined with a Leica MZ16 dissecting microscope and a fluorescent desk lamp for illumination. Measurements were taken with the help of an ocular grid. The length of the body was measured in dorsal aspect from the elytral apex to the front of the pronotum. Legs were described in an idealized laterally extended position; there is a dorsal / ventral and an anterior / posterior surface. Habitus illustrations were compiled using a DFC495 camera with L.A.S. 4.8.0 software adapted to a Z6 APO (all from Leica Microsystems, Heerbrugg, Switzerland). Photographic illustrations of genitalia were made using a DFC450 camera with L.A.S. 4.8.0 software adapted to an Axio Imager M2 microscope (Carl Zeiss Microscopy), with 5×, respectively 10× A-Plan lenses; resulting image stacks were compiled using the Helicon Focus 6.7.1 Pro software (Helicon Soft Ltd). For photography genitalia were temporarily embedded in glycerol gelatin as described by Riedel (2005), with their longitudinal axis somewhat lifted caudally, to adequately illustrate structures of the curved down apex. All photographs were enhanced using the programs Adobe Photoshop CS2 and CS6. However, care was taken not to obscure or alter any features of the specimens illustrated. Sequence data were submitted to GenBank of NCBI (National Center for Biotechnology Information) and the accession numbers are provided under each species, e.g., as “(EMBL # MN322570)”.

Taxonomy

Trigonopterus Fauvel, 1862

Type species, by monotypy

Trigonopterus insignis Fauvel, 1862.

Diagnosis

Fully apterous genus of Cryptorhynchinae s. s. Length 1.5–6.0 mm. Rostrum in repose not reaching middle of mesocoxa. Scutellar shield completely absent externally. Mesothoracic receptacle deep, posteriorly closed. Metanepisternum completely absent externally. Elytra with nine striae (sometimes superficially effaced). Tarsal claws minute. Usually body largely unclothed, without dense vestiture. For additional information, see http://species-id.net/wiki/Trigonopterus.

Descriptions of species

Trigonopterus atuf Narakusumo & Riedel, sp. nov.

Diagnostic description

Holotype. Male (Fig. 1a). Length 2.65 mm. Color of antennae and legs ferruginous, remainder black. Body elongate subovate; profile dorsally convex; in dorsal aspect and in profile with weak constriction between pronotum and elytron. Eyes dorsally approximate. Rostrum with median carina and pair of submedian ridges, intervening furrows with suberect scales. Pronotum subglabrous, punctate. Elytra subglabrous, striae marked by rows of minute punctures and fine hairlines; along base towards humerus bordered by transverse row of deeper punctures; intervals subglabrous, with sparse minute punctures; subapically along ventral margin with row of white scales. Femora with distinct anteroventral ridge, edentate. Mesofemur and metafemur dorsally densely squamose with white scales. Metafemur with smooth dorsoposterior edge; subapically without stridulatory patch. Procoxa with patch of erect white scales. Abdominal ventrites 1–2 concave, medially subglabrous, laterally with sparse white scales; ventrite 5 with shallow impression, punctate, with sparse suberect scales. Penis (Fig. 1b) with sides subparallel, apex subtruncate, with sparse setae, medially with angulate extension; apodemes 3.0× as long as body of penis; transfer apparatus complex; ductus ejaculatorius without bulbus. Intraspecific variation. Length 2.30–2.78 mm. Female rostrum subglabrous, punctate-rugose; in basal quarter with suberect scales. Female abdominal ventrite 5 flat.

Figure 1. 

Trigonopterus atuf Narakusumo & Riedel, sp. nov., holotype a habitus b penis.

Material examined

Holotype (MZB): MZB0014 (GenBank # MN322570), Indonesia, Maluku, Tanimbar, Yamdena Is, Lorulun, 07°48.788'S, 131°22.443'E to 07°48.137'S, 131°21.873'E, 140 m, beaten, 2-V-2017. Paratypes (MZB, SMNK): Indonesia, Maluku, Tanimbar: 13 exx, MZB0012 (EMBL # MN322578) MZB0013 (GenBank # MN322580) MZB0015 (GenBank # MN322569) same data as holotype; 3 exx, MZB0017 (GenBank # MN322568), MZB0018 (GenBank # MN322567), MZB0024 (GenBank # MN322579), Selaru Is, Bangruti, 08°07.253'S, 131°02.947'E, 35 m, beaten, 22-IV-2018; 5 exx, MZB0031 (GenBank # MN322577), MZB0032 (GenBank # MN322576), MZB0040 (GenBank # MN322571), Yamdena Is, Lorulun, Jungle Camp, 07°46.46'S, 131°20.482'E, 110 m, beaten, 19-IV-2018; 1 ex, MZB0034 (GenBank # MN322574), Yamdena Is, Lorulun, Jungle track, 07°47.396'S, 131°20.849'E, 120 m, beaten, 19–20-IV-2018; 47 exx MZB0038 (GenBank # MN322573), MZB0039 (GenBank # MN322572), Yamdena Is, Lorulun, Jungle camp, 07°46.46'S, 131°20.482'E, 110 m, beaten, 24-IV-2018; 2 exx, MZB0033 (GenBank # MN322575), Yamdena Is, Lorulun, Jungle camp, 07°46.46'S, 131°20.482'E, 110 m, beaten, 27-IV-2018.

Distribution

Maluku Prov., Tanimbar (Yamdena Is, Selaru Is). Elevation: 35–120 m.

Biology

On foliage in lowland forest.

Etymology

The epithet is a noun in apposition. Atuf is a mythical warrior from the folklore of the Tanimbar people who defeated the sun.

Notes

This species is closely related to Trigonopterus species 773 from New Guinea, which differs by having a more distinct punctation and 15.1% p-distance of its cox1 sequence.

Trigonopterus kumbang Narakusumo & Riedel, sp. nov.

Diagnostic description

Holotype. Male (Fig. 2a). Length 3.12 mm. Color of antennae ferruginous, remainder black. Body subovate; in dorsal aspect and in profile with weak constriction between pronotum and elytron. Eyes dorsally approximate. Rostrum in basal 1/2 dorsally weakly swollen, with median ridge, coarsely punctate, with dense white scales; in apical half flat, subglabrous, sparsely punctate. Pronotum subglabrous, sparsely punctate with small punctures, somewhat denser and larger along basal margin. Elytra subglabrous, with sparse minute punctures, laterally and subapically striae marked by sparse rows of small punctures; stria 8 along humerus with short row of seven deeper punctures. Femora with distinct anteroventral ridge, near middle with denticle. Mesofemur and metafemur dorsally densely squamose with white scales. Metafemur with smooth dorsoposterior edge; subapically without stridulatory patch. Mesocoxa with densely squamose patch. Abdominal ventrites 1–2 concave, subglabrous, laterally with sparse white scales; ventrite 5 flat, subglabrous, microreticulate, with minute punctures, laterally with coarse punctures and sparse white scales. Penis (Fig. 2b) with sides subparallel, apically subangulate. Transfer apparatus simple, dentiform. Apodemes 2.6× as along as body of penis; ductus ejaculatorius with indistinct bulbus. Intraspecific variation. Length 3.12–3.53 mm. Female rostrum in apical 2/3 dorsally flat, subglabrous, with minute punctures; in basal 1/3 dorsally swollen, coarsely punctate. Female abdominal ventrites 1–2 flat.

Figure 2. 

Trigonopterus kumbang Narakusumo & Riedel, sp. nov., holotype a habitus b penis.

Material examined

Holotype (MZB): MZB0002 (GenBank # MN322581), Indonesia, Maluku, Tanimbar, Yamdena Is, Lorulun, 07°48.788'S, 131°22.443'E to 07°48.82'S, 131°21.524'E, 140 m, beaten, 29-IV-2017. Paratypes (MZB, SMNK): Indonesia, Maluku, Tanimbar: 7 exx, MZB0001 (GenBank # MN322586), MZB0003 (GenBank # MN322585) same data as holotype; 1 ex, MZB0026 (GenBank # MN322582), Yamdena Is, Lorulun, Jungle Camp, 07°46.46'S, 131°20.482'E, 112m, beaten, 24-IV-2018; 3 exx, MZB0042 (GenBank # MN322584), Larat Is, Nature Reserve, 07°08.747'S, 131°49.092'E, 90 m, beaten, 25–26-IV-2018; 1 ex, MZB0019 (GenBank # MN322583), Larat Is, Nature reserve, 07°08.747'S, 131°49.092'E, 90 m, beaten, 26-IV-2018; 5 exx, Yamdena Is, Lorulun, 07°48.473'S, 131°22.266'E to 07°48.137'S, 131°21.873'E, 140 m, beaten, 02-V-2017.

Distribution

Maluku Prov., Tanimbar (Yamdena Is, Larat Is). Elevation 90–140 m.

Biology

On foliage in lowland forest.

Etymology

This epithet is the Indonesian word for beetle and a noun in apposition.

Note

This species is closely related to the undescribed Trigonopterus species 929 (T. nasutus-group) from the D´Entrecasteaux Islands from which it differs by its smaller body size, a subglabrous side of the pronotum, and a 12.3% p-distance of its cox1 sequence.

Trigonopterus laratensis Narakusumo & Riedel, sp. nov.

Diagnostic description

Holotype: Male (Fig. 3a). Length 2.53 mm. Color of head, femora and tibiae ferruginous; remainder black. Body subovate; in dorsal aspect almost without constriction between pronotum and elytron; profile dorsally convex. Rostrum in basal 1/2 with median costa and submedian ridges, intervening furrows with sparse, suberect scales. Pronotum subglabrous, sparsely punctate with small to minute punctures; anterolaterally with coarse punctures. Elytra subglabrous, punctate with minute punctures; striae marked by faint hairlines. Femora subglabrous weakly microreticulate, with minute punctures; with anteroventral ridge distinct, simple. Meso- and metafemur dorsally squamose with white scales. Mesotibia basally rounded; subapically with uncus and larger premucro. Metafemur subapically simple, without stridulatory patch; with uncus, without premucro. Abdominal ventrites 1–2 medially concave, subglabrous, microreticulate; ventrite 2 posteriorly projecting and forming edge; ventrite 5 almost flat, weakly concave, microreticulate. Penis (Fig. 3b) with side subparallel; apex symmetrical, with median triangular extension; transfer apparatus dentiform, apically bordered by pair of L-shaped sclerites; apodemes 3.0× as long as body of penis; ductus ejaculatorius with indistinct bulbus. Intraspecific variation. Length 2.48–2.53 mm. Female rostrum dorsally subglabrous, punctate; in basal 1/3 with median and submedian ridges. Female mesotibia subapically with uncus and minute premucro. Female abdominal ventrites 1–2 flat, with sparse punctures; ventrite 5 flat, subglabrous.

Figure 3. 

Trigonopterus laratensis Narakusumo & Riedel, sp. nov., holotype a habitus b penis.

Material examined

Holotype (MZB): MZB0022 (GenBank # MN322587), Indonesia, Maluku, Tanimbar, Larat Is, Nature reserve, 07°08.747'S, 131°49.092'E, 85 m, beaten, 25–26-IV-2018. Paratype (SMNK): Indonesia, Maluku, Tanimbar: 1 ex, MZB0027 (GenBank # MN322588), Yamdena Is, Lorulun, Jungle Camp, 07°46.46'S, 131°20.482'E, 110 m, beaten, 24-IV-2018.

Distribution

Maluku Prov., Tanimbar (Yamdena Is, Larat Is). Elevation: 85–110 m.

Biology

On foliage in lowland forest.

Etymology

This epithet is based on the type locality Larat Island.

Notes

This species belongs to the T. politus group. It is most closely related to a clade comprising T. allotopus Riedel, T. pseudallotopus Riedel, and some undescribed species from New Guinea, but it has no close relationship to the clade of Australian species.

Trigonopterus porg Narakusumo & Riedel, sp. nov.

Diagnostic description

Holotype. Male (Fig. 4a). Length 2.98 mm. Color of antennae, legs and elytra ferruginous, remainder black. Body elongate; in dorsal aspect and in profile with moderate constriction between pronotum and elytron. Rostrum in basal 2/3 with median carina, dorsal surface clothed with white scales; in apical 1/3 subglabrous, punctate-rugose, with suberect setae. Pronotum densely punctate, with large punctures, with subglabrous midline; anterolaterally with white scales. Elytra subglabrous with irregular small punctures; few striae faintly marked by hairlines. Femora with distinct anteroventral ridge, ending near middle with small tooth. Meso- and metafemur dorsally with silvery scales. Metafemur subapically with stridulatory patch. Abdominal ventrites 1–2 concave, subglabrous, posteriorly sparsely punctate, with sparse scales; ventrite 5 weakly concave with sparse setae. Penis (Fig. 4b) with sides subparallel, in apical 1/3 converging to subangulate apex; transfer apparatus denticulate; apodemes 1.6× as long as body of penis; ductus ejaculatorius with distinct bulbus. Intraspecific variation. Length 2.75–2.98 mm. Female rostrum with subglabrous median costa, laterally punctate-rugose, with short setae. Female pronotum anterolaterally with scales transparent-yellowish. Female abdominal ventrites 1–2 concave, subglabrous with short setae. Female ventrite 5 flat.

Figure 4. 

Trigonopterus porg Narakusumo & Riedel, sp. nov., holotype a habitus b penis.

Material examined

Holotype (MZB): MZB0043 (GenBank # MN322591), Indonesia, Maluku, Tanimbar, Larat Is, Nature reserve, 07°08.747'S, 131°49.092'E, 85 m, beaten, 25–26-IV-2018. Paratypes (MZB, SMNK): Indonesia, Maluku, Tanimbar: 4 exx, MZB0016 (GenBank # MN322590), MZB0044 (GenBank # MN322589) same data as holotype.

Distribution

Maluku Prov., Tanimbar (Larat Is). Elevation ca. 85 m.

Biology

On foliage in lowland forest.

Etymology

This epithet is a noun in apposition based on the fictional penguin-like character Porg in the Star Wars movies. This species inhabiting a remote island has the same color combination of black, orange and white.

Notes

This species is closely related to the undescribed species 437 from Kai Kecil Island from which it differs by the elytral color and a 13.6% p-distance of its cox1 sequence.

Trigonopterus selaruensis Narakusumo & Riedel, sp. nov.

Diagnostic description

Holotype: Female (Fig. 6.a) Length 2.95 mm. Color of antennae ferruginous, head and legs dark ferruginous, remainder black. Body subovate; in dorsal aspect with weak constriction between pronotum and elytron; profile dorsally convex. Eyes dorsally approximate. Rostrum in basal 1/3 with median ridge and pair of submedian ridges; with suberect white scales; in apical half dorsally flattened, subglabrous, punctate Pronotum densely punctate with small punctures. Elytra subglabrous; striae marked by rows of minute punctures; intervals subglabrous and with row of even smaller punctures; along base and behind humerus bordered by row of deep punctures. Femora with distinct anteroventral ridge, near middle with denticle. Mesofemur and metafemur dorsally densely squamose with white scales. Metafemur with smooth dorsoposterior edge; subapically without stridulatory patch. Abdominal ventrites 1–2 flat, subglabrous, sparsely punctate, with sparse scales; ventrite 5 flat, punctate, sublaterally with suberect scales. Genitalia (Fig. 5b).

Figure 5. 

Trigonopterus selaruensis Narakusumo & Riedel, sp. nov., holotype a habitus b female genitalia.

Figure 6. 

Trigonopterus tanimbarensis Narakusumo & Riedel, sp. nov., holotype a habitus b penis.

Material examined

Holotype (MZB): MZB0023 (GenBank # MN322592), Indonesia, Maluku, Tanimbar, Selaru Is, Bangruti, 08°07.253'S, 131°02.947'E, 35 m, beaten, 22-IV-2018.

Distribution

Maluku Prov., Tanimbar (Selaru Is). Elevation 35 m.

Biology

On foliage in lowland forest.

Etymology

This epithet is an adjective derived from the species´ type locality, Selaru Island.

Notes

This species is closely related to the undescribed Trigonopterus species 436 from Kai Kecil Island, from which it differs by a larger body size and a more densely punctate pronotum and an 8.9% p-distance of its cox1 sequence.

Trigonopterus tanimbarensis Narakusumo & Riedel, sp. nov.

Diagnostic description

Holotype. Male (Fig. 6a). Length 3.06 mm. Color of antennae and tarsi ferruginous, remainder black. Body slender subovate; profile dorsally convex; in dorsal aspect and in profile with weak constriction between pronotum and elytron. Rostrum dorsally with median ridge somewhat flattened at level of antennal insertion; with fine submedian ridges; in basal 1/2 with dense silvery scales, in apical 1/2 with suberect setae. Pronotum densely punctate; punctures becoming larger anterolaterad; each puncture containing short seta; with subglabrous midline. Elytra with striae marked by rows of small punctures and fine hairlines; basal margin bordered by transverse row of deeper punctures; intervals subglabrous, with interspersed minute punctures. Femora with anteroventral ridge weakly crenate, ending in apical half with small tooth. Metafemur dorsally with recumbent silvery scales; dorsoposterior edge indistinct, weakly denticulate-crenate, subapically with stridulatory patch. Abdominal ventrites 1–2 concave, coarsely punctate, at middle subglabrous; ventrite 5 with shallow impression, densely punctate, sparsely setose, laterally with sparse scale. Penis (Fig. 6b) with sides subparallel, apex subangulate, setose; transfer apparatus complex; sclerites of endophallus and orifice asymmetrical; apodemes 2.1× as long as body of penis; ductus ejaculatorius with indistinct bulbus. Intraspecific variation. Length 2.75–3.25 mm. Female rostrum slender, dorsally with subglabrous median costa, with sublateral rows of punctures, in basal 1/3 with sparse suberect scales. Female abdominal ventrites 1–2 flat. Female abdominal ventrite 5, punctate.

Material examined

Holotype (MZB): MZB0010 (GenBank # MN322598), Indonesia, Maluku, Tanimbar, Yamdena Is, Lorulun, 07°48.788'S, 131°22.443'E to 07°48.137'S, 131°21.873'E, 140 m, beaten, 02-V-2017. Paratypes (MZB, SMNK): Indonesia, Maluku, Tanimbar: 7 exx, MZB0008 (GenBank # MN322600), MZB0009 (GenBank # MN322599), MZB0011 (GenBank # MN322593), same data as holotype; 4 exx. MZB0035 (GenBank # MN322596), Yamdena Is, Lorulun, Jungle Camp, 07°46.46'S, 131°20.482'E, 110 m, beaten, 19-IV-2018; 53 exx. MZB0028 (GenBank # MN322597) MZB0037 (GenBank # MN322594), Yamdena Is, Lorulun, Jungle Camp, 07°46.46'S, 131°20.482'E, 110 m, beaten, 24-IV-2018; 1 ex., MZB0036 (GenBank # MN322595), Yamdena Is, Lorulun, Jungle Track, 07°47.396'S, 131°20.849'E, 120 m, beaten, 19–20-IV-2018.

Distribution

Maluku Prov., Tanimbar (Yamdena Is). Elevation 110–140 m.

Biology

On foliage in lowland forest.

Etymology

This epithet is an adjective derived from the Tanimbar Archipelago.

Notes

This species appears related to a species from New Guinea (species 959) from which it is differs by 19.9% p-distance of its cox1 sequence and many morphological characters.

Trigonopterus triradiatus Narakusumo & Riedel, sp. nov.

Diagnostic description

Holotype. Male (Fig. 7a). Length 3.03 mm. Color of antennae ferruginous, legs dark ferruginous, remainder black. Body subovate; in dorsal aspect and in profile with weak constriction between pronotum and elytron. Eyes dorsally approximate. Rostrum in basal 1/2 with median ridge and pair of sublateral ridge; intervening furrows with suberect scales; apical half subglabrous, punctate. Pronotum with disk subglabrous, with minute sculpture; in basal 1/3 laterally with indistinct edge lined with few coarse punctures; laterally anterior margin lined by few white scales, behind eye with row of coarse punctures. Elytra subglabrous, with minute punctures. Femora edentate; with distinct anteroventral ridge. Mesofemur and metafemur dorsally densely squamose with white scales. Metafemur with smooth dorsoposterior edge; subapically without stridulatory patch. Abdominal ventrites 1–2 medially concave, subglabrous, laterally with sparse white scales; ventrite 5 at middle with shallow impression, weakly punctate, with sparse short setae. Penis (Fig. 7b) with sides converging to slightly spatulate apex; transfer apparatus complex; endophallus with triradiate sclerites; apodemes 1.5× as long as body of penis; ductus ejaculatorius with distinct bulbus. Intraspecific variation. Length 2.68–3.53 mm. Female rostrum slender, subglabrous, sparsely punctate, in basal 1/4 with indistinct ridges and sparse suberect scale. Female abdominal ventrite 5 flat, subglabrous, with small punctures.

Figure 7. 

Trigonopterus triradiatus Narakusumo & Riedel, sp. nov., holotype a habitus b penis.

Material examined

Holotype (MZB): MZB0007 (GenBank # MN322604), Indonesia, Maluku, Tanimbar, Yamdena Is, Lorulun, 07°48.788'S, 131°22.443'E to 07°48.137'S, 131°21.873'E, 140 m, beaten, 2-V-2017. Paratypes (MZB, SMNK): Indonesia, Maluku, Tanimbar: 12 exx, MZB0004 (GenBank # MN322607), MZB0005 (GenBank # MN322606), MZB0006 (GenBank # MN322605) same data as holotype; 3 exx, Yamdena Is, Lorulun, 07°48.788'S, 131°22.443'E to 07°48.137'S, 131°21.873'E, 140 m, beaten, 28–29-V-2017; 7 exx, MZB0029 (GenBank # MN322601) MZB0030 (GenBank # MN322602) Yamdena Is, Lorulun, Jungle Camp, 07°46.46'S, 131°20.482'E, 110 m, beaten, 24-IV-2018; 1 ex, Yamdena Is, Lorulun, Jungle Camp, 07°46.46'S, 131°20.482'E, 110 m, beaten, 19-IV-2018; 1 ex, MZB0021 (GenBank # MN322608) Larat Is, margin of Nature reserve, 07°08.22'S, 131°49.49'E, 40 m, 25-IV-2018; 1 ex, MZB0041 (GenBank # MN322603) Larat Is, Nature reserve, 07°08.747'S, 131°49.092'E, 85 m, beaten, 25–26-IV-2018; 2 exx, MZB0025 (GenBank # MN322609), MZB0112 (GenBank # MN322610), Selaru Is, Bangruti, 08°07.253'S, 131°02.947'E, 40 m, beaten, 22-IV-2018.

Distribution

Maluku Prov., Tanimbar (Yamdena Is, Larat Is, Selaru Is). Elevation: 40–140 m.

Biology

On foliage in lowland forest.

Etymology

This epithet is an adjective based on triradiate sclerites in the endophallus of the species.

Note

This species is closely related to Trigonopterus species 60 from Papua New Guinea from which it differs by the structure of the penis and a 17.8% p-distance of its cox1 sequence.

Key to the Trigonopterus species of the Tanimbar Archipelago

1 Metafemur subapically with stridulatory patch. Pronotum densely punctate 2
Metafemur subapically without stridulatory patch. Pronotum subglabrous, sparsely punctate with small or minute punctures 3
2 Elytra black. Basal half of rostrum and forehead with silvery scales not covering the surface. Side of pronotum anteriorly without scales T. tanimbarensis sp. nov.
Elytra ferruginous. Basal half of rostrum and forehead almost covered by white scales. Side of pronotum anteriorly with white scales T. porg sp. nov.
3 Femora with simple anteroventral ridge; edentate 4
Femora with ventral denticle 6
4 Eyes medially approximate; base of rostrum much wider than forehead between eyes. Apex of male mesotibia only with uncus 5
Base of rostrum subequal to forehead between eyes. Apex of male mesotibia with enlarged premucro T. laratensis sp. nov.
5 Body slender. Pronotum sparsely punctate. Elytral striae marked by rows of minute punctures and fine hairlines T. atuf sp. nov.
Body wider. Pronotum subglabrous. Elytra subglabrous, without distinct striae T. triradiatus sp. nov.
6 Elytral base bordered by row of deeper punctures. Apex of metatibia with supra-uncal denticle T. selaruensis sp. nov.
Elytral base without deeper punctures (except row hidden behind humerus). Apex of metatibia dorsally of uncus rounded T. kumbang sp. nov.

Discussion

Trigonopterus had hitherto been recorded from Ceram Island (Riedel 2011), Flores of the Lesser Sunda Islands (Riedel et al. 2014), the Aru Islands (Pascoe 1885), Eastern Australia (Riedel and Tänzler 2016), and New Guinea (Riedel 2011, Riedel et al. 2013b). The newly discovered Trigonopterus fauna of the Tanimbar Islands fills a gap in the known distribution and is of special interest due to the isolated position and recent geological age of these islands. The islands of Sumba, Alor, Timor, and Wetar should be searched for additional undescribed species in future.

All the discovered species of Tanimbar Trigonopterus live on foliage, and no edaphic lineage could be found. This may be due to the relatively dry climatic conditions, which may be putting stress on species that depend on a layer of moist litter. Alternatively, it is possible, that edaphic species are present but have eluded discovery so far; sifting of leaf litter under the right conditions, e.g., after sufficient rainfalls, may bring them to light.

Morphologically the Tanimbar Trigonopterus species are very different from each other, a fact supported by the molecular dataset of their cox1 sequences. Therefore, no closely related species pairs can be recognized, i.e., there is no indication for any autochthonous speciation on the Tanimbar Archipelago. Instead, the Trigonopterus fauna has been formed largely by repeated dispersal from neighboring regions, i.e., from Western New Guinea and the Moluccas. The sister species of T. porg sp. nov. (13.6% p-distance of cox1) and T. selaruensis sp. nov. (8.9% p-distance of cox1) were both found on Kai Kecil Island 190 km to the Northeast. Trigonopterus triradiatus sp. nov. is related to Trigonopterus species 60 from Papua New Guinea (17.8% p-distance of cox1). Trigonopterus laratensis sp. nov. belongs to a clade comprising T. allotopus Riedel, T. pseudallotopus Riedel, and some undescribed species from New Guinea (15.6% p-distance of cox1), but has no close relationship to the clade of Australian species of the T. politus-group. Trigonopterus kumbang sp. nov. belongs to the T. nasutus-group and appears most closely allied to Trigonopterus species 929 (12.3% p-distance of cox1) from the D’Entrecasteaux Islands. Trigonopterus atuf sp. nov. is closely related to Trigonopterus species 773 (15.1% p-distance of cox1) from Papua New Guinea. Trigonopterus tanimbarensis sp. nov. appears related to a species from New Guinea (Trigonopterus species 959; 19.9% p-distance of cox1).

With its close proximity to Australia, stronger ties to the Australian fauna could be expected, but apparently this is not the case. An explanation could be that the Australian species are largely restricted to the Cape York Peninsula and the east coast of Queensland, which is quite distant from the Tanimbar Islands, and that the absence of Trigonopterus from the Northern Territory in Australia could be a real gap in the distribution of the genus and not just a sampling artifact, caused by environmental extremes.

All in all, the observed composition of the Trigonopterus fauna of the Tanimbar Archipelago is exactly what can be expected from the geological setting and what has been observed in other taxa (How and Kitchener 1997; Beck et al. 2006; Michaux 2010; Andersen et al. 2013): 1) a relatively recent origin that may not have allowed for local speciation and 2) an insular situation not compromised by periods of low sea level. This is quite different in the otherwise similar Aru Islands further east which were part of the continuous Sahul shelf during the Pleistocene. However, no focused fieldwork has ever been carried out on the Aru Islands, from which only T. oblongus Pascoe is known to date. Presumably, further collecting on these islands would discover additional species with stronger ties to the Southern Papuan fauna.

The rapid and ongoing anthropogenic activities in Tanimbar, i.e., agriculture and forestry, put pressure on the natural forests of the islands, which are the exclusive habitats of Trigonopterus species. The first author found the southern part of Yamdena Island to be extensively logged, and most areas of the eastern coast have been converted to agriculture and settlements. The forests of Larat Island are also severely affected by agriculture, with coconut plantations prevalent inside the wildlife conservation area. Finally, Selaru Island without any protected areas, has suffered worst from logging; its interior has already been turned into grassland and the remaining forests areas are fragmented on the sparse rocky soil that is almost useless for gardening. Such destructions of natural forest areas in Tanimbar threaten not only the endemic Trigonopterus species but also the remaining biodiversity of this fascinating archipelago.

Acknowledgements

We would like to thank the Indonesian Ministry of Environment and Forestry and Center for natural resources conservation (BKSDA) of Maluku for the permits to enter conservation areas and to collect wildlife. Specimens were exported as a loan from MZB. Thanks to Anang Setiawan Achmadi (MZB) and Ibnu Maryanto (MZB) for making it possible that RPN could join their expedition to the Tanimbar Archipelago. Special thanks to Wilhelmus Samangun (Tanimbar), Vera (Tanimbar), Mark O’Hara (Vienna), Berenica Mioduszewska (Vienna), and Tri Haryoko (MZB) in allowing RPN to use their wonderful field station, Suprayitno (Denpasar) for the companionship during the first trip, and I Nyoman Sumerta (InaCC), Ruby Setiawan (InaCC), and the people of Lorulun, Adaut, and Keliobar for helping RPN during the fieldwork. Sequencing runs were done by A. Brachmann and G. Brinkmann of the LMU sequencing unit (Munich). This work was funded by the German Academic Exchange Service DAAD (91654661 to R.P.N.), pilot project funding from the laboratory of Michael Balke, DIPA KSK Pengembangan Database KEHATI PDII 2018 and the German Research Foundation DFG (RI 1817/3-4 to A.R.).

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