A new species of Synchonnus ( Coleoptera : Lycidae ) from New Guinea , with an identi fi cation key to the Papuan species

The Papuan fauna of Synchonnus Waterhouse, 1879 contains only four species distributed in Mysool, Japen, and New Guinea and is less diversifi ed than those of the continental Australia where 16 species have been recorded. Synchonnus occurs in lowlands and in lower mountain forests. A new species, Synchonnus etheringtoni sp. nov., is described from New Guinea, and S. testaceithorax Pic, 1923 is redescribed. All Papuan species are keyed.


Introduction
Papuan net-winged beetles are represented mostly by the subtribe Metriorrhynchina (Lycidae: Metriorrhynchini), and only a few other net-winged beetle tribes and subfamilies have been recorded in New Guinea and the adjacent islands (BOCAK & BOCAKOVA 2008;SKLENAROVA et al. 2013).Although the fi rst Papuan species were described already at the beginning of the 19 th century by GUÉRIN-MÉNEVILLE (1830-1838) and further about two hundred species before the second world war (KLEINE 1926), the diversity of the Papuan net-winged beetle fauna has not been systematically studied except for a few genus restricted reviews (e.g., BOCAKOVA 1992, BOCEK & BOCAK 2016).Most taxonomic information is represented by isolated descriptions without any reference to the species described earlier.
Synchonnus Waterhouse, 1879 was originally defi ned using only external characters, such as pronotal carinae, which are often misleading, especially when the arrangement of pronotal carinae and the number of elytral costae are used as principal traits for generic delimitation (SKLENAROVA et al. 2014).Strophicus Waterhouse 1879 was synonymized to Enylus Waterhouse, 1879 (BOCAK 2002).All known species of Synchonnus can be now identifi ed only using simultaneously the shape of pronotal ridges and the morphology of male genitalia (KUSY et al. 2017).Synchonnus is now treated as a genus merging all species previously placed in Synchonnus, Achras Waterhouse, 1879, Enylus, and Strophicus (KLEINE 1933, KUSY et al. 2017).Recently, molecular studies placed Synchonnus in relationships with Leptotrichalus Kleine, 1926 andWakarumbia Bocak, 1999 and showed that the delimitations of the genera Achras and Enylus were unjustifi ed and these are junior synonyms of Synchonnus (SKLENAROVA et al. 2013, KUSY et al. 2017).
Recently, two species of Synchonnus from New Guinea were obtained and hence, the description of one new species and redescription of another, poorly known species from New Guinea, are provided.Although the wide distribution of species from the adjacent islands has not yet been reported, these species are added to the identifi cation key to all species from the Papuan Region.

Material and methods
The specimens were preserved in alcohol in the fi eld and dry-mounted after the removal of metathoracic muscles for future genetic studies.Morphological descriptions are based on adults, the larvae of Synchonnus remain unknown.Photographs were taken by a digital camera attached to a binocular microscope and assembled from several layers in Helicon Focus 6. Whole bodies were relaxed in 50% alcohol, the tip of the abdomen was detached, and muscles and fat tissues were cleared in hot 10% KOH.Then, genitalia were dissected.All measurements were taken using an ocular grid.The examined material is deposited in the Ladislav Bocák collection deposited at the Department of Zoology, Palacky University in Olomouc, Czech Republic (LMBC).The types of the previously described species were studied in the Museum national dʼHistoire naturelle in Paris and the Natural History Museum in London.Abbreviations: BL -body length, WH -width at humeri, PL -pronotum length, PW -pronotum width, Edist -eye distance, Ediam -eye diameter, PhL -phallus length.Redescription.Body weakly sclerotized, dorso-ventrally fl attened, 5-12 mm long (Figs 1-2).Head small, without rostrum, partially hidden by pronotum, antennae serrate in both sexes, never fl abellate, antennomere I pear-shaped, antennomere II very short, transverse, antennomeres III-XI longer than wide, fl at, sometimes acutely pointed (Figs 5-6); mandibles simple, slightly curved, without any teeth, maxillary palpi 4-segmented, slightly compressed, apical palpomere fl at, securiform, labial palpi 3-segmented, similar in shape.Pronotum fl at, transverse, with slightly elevated lateral margins, frontal margin widely rounded, projected anteriorly, lateral margins variable in shape, basal margin bisinuate to almost straight, anterior angles well marked but obtuse, sometimes inconspicuous, widely rounded, posterior angles rectangular to acutely projected; disc with three to fi ve areoles, antero-lateral carinae always absent, postero-lateral carinae sometimes well developed, median areola always present, very slender to moderately wide, either directly attached to anterior and posterior margins or connected with anterior margin by short keel (Figs 3-4).Elytra weakly sclerotized, fl at, apices independently rounded; elytra regularly apparently wider than abdomen, each elytron with four primary and fi ve secondary longitudinal costae; primary costae always strong in humeral third of elytra, primary costae 2 and 4 sometimes very strong in whole length, costae 1 and 3 always weaker, especially in apical part; secondary costae often irregular, especially in apical part of elytra (Figs 9-10).Male genitalia with phallus and phallobase only, parameres absent, membrane in ventral part of phallobase never sclerotized, phallus variable in shape, very slender to short and robust, most species with two thorns in internal sac, their position variable, either located in basal part and then connected with apical membranes by pigmented duct or present in apical part of phallus, only seldom thorns absent.Differential diagnosis.When a limited number of species was known, variability in the number of pronotal areolae led to the description of four separate genera (WATERHOUSE 1879).

Taxonomy
Based on molecular phylogeny, the status of these genera was revised (KUSY et al. 2017).Now, Synchonnus contains species which have diverse male genitalia and pronotal carinae.
All Synchonnus have vestigial (Fig. 3) to absent (Fig. 4) antero-lateral pronotal costae.Additionally, they have symmetrical phallus with thorns in the internal sac, but the shape of the phallus and the position of the thorns are variable.Phallus can be long and slender, but also robust and short (KUSY et al. 2017) Redescription.Female.BL 8.9 mm, WH 2.38 mm, PL 1.38 mm, PW 2.20 mm.Body robust, black, only pronotum, scutellum and basal part of femora orange (Fig. 1).Head small, antennae strongly compressed, serrate (Fig. 5), reaching to two-thirds of elytral length.Pronotum trapezoidal, 1.59 times wider than long at the midline, widest basally, anterior margin widely rounded, lateral margins straight to slightly convex, posterior angles robust, prominent, median areola relatively wide, connected to anterior margin by short longitudinal carina; anterior angles obtuse, (Fig. 3).Elytra 3.17 times longer than wide at humeri, costae 2 and 4 stouter than others, costa 3 shortened and weakly developed in almost whole length, secondary costae present in whole elytra, elytral cells mostly quadrate (Fig. 9).Male.Unknown.Differential diagnosis.Synchonnus testaceithorax is characterized by uniformly orange pronotum without any patches, completely black elytra, and reddish to dark brown head.Synchonnus testaceithorax is the only species of the genus with a very different strength of elytral longitudinal costae.Costae 1 and 3 are extremely strong in comparison with all other species placed in the genus.Ecological information.Synchonnus testaceithorax was collected on shaded vegetation in the lowland forest in the central part of the Mamberamo valley.The orange-black aposematic pattern was the most represented in the collected material.Distribution.New Guinea, the lower Mamberamo Basin.Remarks.The type of S. testaceithorax has not been found in the collection of M. Pic deposited in the Paris museum and only the original description (PIC 1923) is available for recognition of this species.As no difference was identifi ed, and the fauna of the New Guinean lowlands contains widely distributed species, we identify the available specimen as S. testaceithorax and provide the redescription and illustrations of this species based on the abovementioned specimen.
Female.Unknown.Differential diagnosis.The other three species of Synchonnus in the Papuan region have uniformly light coloured pronotum, and S. etheringtoni sp.nov. is the only one with a dark patch in the anterior part and along the median areola.Additionally, the species differs in sharply prominent posterior pronotal angles and dense pubescence (Fig. 4).Synchonnus testaceithorax Pic, 1923 differs from S. etheringtoni sp.nov. in red to dark brown colouration of its head and much more apparent vestiges of lateral pronotal carinae delimiting lateral areoles (Fig. 3).Synchonnus segregatus Waterhouse, 1879 occurs only in Mysool and has slender, parallel-sided pronotum, and S. humeralis from Japen has light coloured humeri.Ecological information.Synchonnus etheringtoni sp.nov.was identifi ed in an extensive material collected in the lower mountain forest.(Waterhouse, 1879)

Synchonnus Waterhouse, 1879
. Always two separate tho, 2014) present, they are close to each other and can be located either at the base of the phallus, in the middle part or close to the apex.Synchonnus belongs to a clade with Leptotrichalus Kleine, 1926 from Sulawesi and the Oriental Region, and Wakarumbia Bocak, 1999 from Sulawesi(SKLEN- AROVA et al. 2013, 2014).Leptotrichalus differs in the slender pronotum, absent thorns in the internal sac and shortened elytral costa 1. Wakarumbia has always fi ve well marked areoles of a characteristic shape, unlike Synchonnus with well developed postero-lateral pronotal costae.Further it has a complex fused thorn in the basal part of the internal sac, very extensive ventral membranous part in the phallus, and many species have the asym-