Synchonnus Waterhouse, 1879

Kusy, Dominik, 2017, A new species of Synchonnus (Coleoptera: Lycidae) from New Guinea, with an identification key to the Papuan species, Acta Entomologica Musei Nationalis Pragae 57 (1), pp. 153-160 : 154-155

Synchonnus Waterhouse, 1879

Synchonnus Waterhouse, 1879: 59 (original description). Type species: Porrostoma clientulum Waterhouse, 1877 (by monotypy).

Achras Waterhouse, 1879:61 (original description). Type species: Achras limbatum Waterhouse,1879 (by monotypy). KUSY et al. (2017): 55 (synonymy).

Enylus Waterhouse, 1879: 72 (original description). Type species: Enylus segregatus Waterhouse, 1879 (by monotypy). KUSY et al. (2017): 5 (synonymy).

Strophicus Waterhouse, 1879: 73 (original description). Type species: Strophicus nigellus Waterhouse, 1879: 73 (by monotypy). BOCAK (2002): 335 (synonymy); KUSY et al. (2017): 5 (synonymy).

Redescription. Body weakly sclerotized, dorso-ventrally flattened, 5–12 mm long ( Figs 1–2 ). Head small, without rostrum, partially hidden by pronotum, antennae serrate in both sexes, never flabellate, antennomere I pear-shaped, antennomere II very short, transverse, antennomeres III–XI longer than wide, flat, sometimes acutely pointed ( Figs 5–6 ); mandibles simple, slightly curved, without any teeth, maxillary palpi 4-segmented, slightly compressed, apical palpomere flat, securiform, labial palpi 3-segmented, similar in shape. Pronotum flat, 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 five 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, flat, apices independently rounded; elytra regularly apparently wider than abdomen, each elytron with four primary and five 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). 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). Always two separate thorns are 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 five 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 asymmetrical phallic apex ( BOCAK 2000). The distantly related trichaline genera have a similar pronotum, but they always have shortened elytral costa 1 and a very different phallus with only partly sclerotized apical part ( BOCAK 2002).

Distribution and abundance. Continental Australia (16 spp.), New Guinea (2 spp.), Japen (1 sp.), and Mysool (1 sp.). In contrast with high relative abundance in the coastal and mountain rainforests of Queensland ( KUSY et al. 2017), Synchonnus is rare in the Papuan region, only a few species have been reported and most of them are known only from single specimens.

Figures

Figs 1–4. Synchonnus species. 1–2 – general appearance (1 – S. testaceithorax Pic, 1923; 2 – S. etheringtoni sp. nov.). 3–4 – detail of pronotum (3 – S. testaceithorax; 4 – S. etheringtoni sp. nov.) Scales = 1 mm (Figs 1–2), 0.5 mm (Figs 3–4).

Figs 5–10. Synchonnus species. 5–6 – basal antennomeres (5 – S. testaceithorax; 6 – S. etheringtoni sp. nov.). 7–8 – male genitalia of S. etheringtoni sp. nov. (7 – ventral view; 8 – lateral view). 9–10 – right elytron, the middle part in detail (9 – S. testaceithorax; 10 – S. etheringtoni sp. nov). Scales = 0.5 mm (Figs 5–10).