Pachyrhynchus viridis (Chevrolat, 1879)

Bollino, Maurizio, 2023, About some Indonesian Pachyrhynchus Germar 1824 with description of a new species (Coleoptera, Curculionidae, Entiminae, Pachyrhynchini), Zootaxa 5227 (4), pp. 495-500 : 498-500

Pachyrhynchus viridis (Chevrolat, 1879)

( Figs. 2B, 2E )

The species was originally placed in the genus Apocyrtus Erichson 1834 by Chevrolat (1879), with type locality “Nova-Guinea (Dorey) [= Manokwari]”. Later, Dalla Torre et al. (1931) treated it as a member of the genus Sphenomorpha Behrens 1887 , a treatment followed by Setliff (2007). Yoshitake (2017), after examination of the holotype in Naturhistoriska riksmuseet, Stockholm, proposed the new combination Pachyrhynchus viridis (Chevrolat) .

Recently I obtained a single male of Pachyrhynchus from Neney village (Ransiki District, Manokwari Province, West Papua) which matches the diagnosis of P. viridis provided by Yoshitake (2017), but the color of the tegument is shiny black. In the same paper, Yoshitake described Pachyrhynchus ohbayashii from Biak Island. Comparing both the diagnosis and images of the two species provided by Yoshitake, I have not been able to attribute my specimen with certainty to one or the other species. Based on the simple topological data I consider it Pachyrhynchus viridis .

Taking advantage of the availability of specimens of four of the five Indonesian species of Pachyrhynchus most phenetically similar to each other, I also wanted to compare the morphology of the male genitalia, as well as attempt the evertion of the endophallus. As already pointed out (Bollino & Sandel, 2017; Cabras et al., 2018), this latter procedure is not simple, and usually requires several attempts with different specimens. I was able to obtain a complete evertion only in P. morotaiensis ( Fig. 2D ) and P. viridis ( Fig. 2E ), and a partial eversion in P. forsteni ( Fig. 2C ), while I have not obtained any results in P. faisali .

The morphology of the aedeagus and/or endophallus of the genus Pachyrhynchus has sometimes been used to propose phyletic relationships between species (Bollino et al., 2017; Cabras et al., 2017; Bollino, 2022). In the species treated here and on the basis of the morphology of the endophallus, it would seem that P. forsteni and P. viridis are more differentiated from the other species of the genus Pachyrhynchus as no other taxon has the long median dorsal diverticulum found in the two Indonesian species (see red arrows in figs. 2C and 2E). Something similar is also present in some Pachyrhynchini belonging to the genus Pantorhytes Faust 1892 , even if the general structure of the endophallus of this genus is simpler and the smaller median diverticulum is ventral (fig. 2F). Pachyrhynchus morotaiensis ,on the contrary, seems in this respect more similar to the rest of the members of the genus Pachyrhynchus .

As regards the morphology of the aedeagus, the only relevant data is the shape of the apex, rounded in P. forsteni , P. morotaiensis and P. faisali , and slightly pointed in P. viridis and P. ohbayashii . The length of the apodemes compared to that of the aedeagus is also different ( P. forsteni LA / LEd: 2.10; P. faisali LA / LEd: 1.62; P. morotaiensis: LA / LEd: 1.41; P. viridis: LA / LEd: 1.55; P. ohbayashii: LA / LEd: 1.79). On the basis of my experience, the length of the apodemes of the Pachyrhynchini is directly proportional to the length of the introflexed endophallus, and therefore of the everted one also.

Figures

FIGURE 2. Pachyrhynchus species, dorsal habitus. A: Pachyrhynchus forsteni male (Morotai); B: Pachyrhynchus viridis (West Papua). Pachyrhynchus species, endophallus in lateral view. C: Pachyrhynchus forsteni (Halmahera); D: Pachyrhynchus morotaiensis (Morotai); E: Pachyrhynchus viridis (West Papua); F: Pantorhytes biplagiatus (Papua New Guinea). Red arrow indicates the dorsal median diverticulum in Pachyrhynchus, and the ventral median one in Pantorhytes.