Rhopaloncus new genus

Philopterus (Goniodes) Nitzsch, 1818: 293. In partim.

“Genus 2”: Gustafsson et al., 2024c: 98.

Type species: Goniodes megaceros Kellogg & Paine, 1914: 227.

Diagnosis. Rhopaloncus can be separated from Goniodes sensu stricto by the following characters (see below for comments on the identity of female Rhopaloncus): coni bent posteriorly in Goniodes (Figs 4–5), but not in Rhopaloncus (Figs 32–33); male scape with one distally squamous process in Goniodes (Fig. 4), but with two such processes in Rhopaloncus (Fig. 32); female with rounded temples in Goniodes (Fig. 3), but with temples extended laterally in Rhopaloncus (Fig. 31); postero-lateral corners of pteronotum flattened and both lpts and ipts lateral in Goniodes (Figs 1, 3), but rounded and only lpts lateral in Rhopaloncus (Figs 30–31); male pteronotum fused to tergopleurite II in Rhopaloncus (Fig. 30), but not in Goniodes (Fig. 1); male tergopleurite IX fused to central plate in Goniodes (Fig. 1), but not in Rhopaloncus (Fig. 30); ventral side of abdomen without rows of microsetae in Goniodes (Figs 1, 3), but with such rows in Rhopaloncus (Figs 30–31); female subgenital plate absent but bifid structure present in Goniodes (Fig. 8), but subgenital plate present and bifid structure absent in Rhopaloncus (Fig. 36); basal apodeme comprising less than half the genital length in Goniodes (Figs 6–7), but comprising more than three-quarters the length in Rhopaloncus (Figs 34–35); mesosome more complicated in structure in Goniodes (Figs 6–7) than in Rhopaloncus (Figs 34–35); parameres distally divergent and widening in Goniodes (Figs 6–7), but parallel or convergent and distal ends narrowly bifid or sinuous in Rhopaloncus (Figs 34–35).

Descriptions

Both sexes. Large chewing lice of the Goniodes body louse ecomorph. Head broader than long, frons gently rounded to somewhat flattened. Marginal carina uninterrupted, terminating proximally in elongated preantennal nodi. Ventral carina uninterrupted; clypeo-labral suture absent. Coni prominent, not bent posteriorly but narrowed to points in females. Antennae sexually dimorphic: in male, scape much swollen and elongated compared to that of female, with two distally squamous processes on posterior margin, the inner process being much longer than the outer process; male pedicel similar to that of female in size, but noticeably curved; male flagellomere I much enlarged compared to that of female and to male flagellomeres II–III, extended distally into curved horn with squamous inner margin. Eyes large. Temples sexually dimorphic, with that of male being largely rounded and that of female being extended laterally into distally flattened point. Occipital process absent in male, present as flattened bulge in female. Head chaetotaxy: dsms, ads, pns, pts, avs2 all mesosetae or longer; mts1, mts3 macrosetae; mts5 situated on occipital process in female; postantennal head with few (less than 10) central sensilla on each side; s1–2, s5–7 present.

Rhombic sclerite small to moderate, clearly separated from pronotum. Pronotum flaring posteriorly, with ppss on postero-lateral corner. Pteronotum roughly pentagonal, fused submedianly to tergopleurite II in male. Postero-lateral corners of pteronotum rounded, with only lpts lateral, but ipts close to postero-lateral corners; smns without visible associated sensillum; mpts situated in hyaline tegument anterior to fusion between pteronotum and tergopleurite II in male. Mesosternum present, metasternum present or absent; mets and mss present. Proepimera large, curling around coxae II, but not fused medianly. Metepisterna not sclerotised medially.

Abdomen rounded in male, more elongate in female. Tergopleurites III–VIII medianly separated, with section medial to spiracular openings conspicuously narrowed in more posterior segments in male. Male tergopleurite IX not fused to central plate, but plates overlapping. Female tergopleurites IX–XI fused together, and medianly continuous. Central sternal plates absent, but abdominal segments II–VI in both sexes with lateral accessory sternal plates. Male abdominal chaetotaxy: tergopleurites II–VIII with tergocentral mesosetae, gradually diminishing in number in more posterior segments, dense rows of tps microsetae, the medial of which may be intercalated with mesosetae, and 2–3 post-spiracular meso- or macrosetae on each side; ventral side of abdominal segment II–VII with multiple sts mesosetae, on segment VIII one macroseta on each side. Female abdominal chaetotaxy: tergopleurites II–V with dense rows of setae likely representing both tcs and tps, but no tps microsetae (more lateral setae in rows may be shorter than more central rows), tergopleurites VI–VII with dense rows of tcs and at least some tps microsetae on each side, but these not forming distinct rows; tergopleurites III–VII with 1–2 psc, tergopleurite VIII with numerous psc, the more medial of which are indistinguishable in length from a row of what is presumably tps; ventral side of abdominal segment II with dense median row of sts, segments III–VI with dense rows of sts and dense row of microsetae anterior to the sts (some intercalated with sts, particularly laterally); segment VII with 0–1 central sts. Male subgenital plate large, expanded laterally; female subgenital plate present, medianly continuous, but poorly sclerotised.

Male genitalia large, reaching to tergopleurite III when non-everted. Basal apodeme long, comprising more than two-thirds the length of genitalia. Distal end may have bifurcated median structure, but it is unclear whether this structure is actually connected to basal apodeme, or comprises the proximal thickening of the mesosome. Mesosome variable among species, ventrally as rounded or semi-oval plate with rugose nodi at or near postero-lateral corners. Parameres long, not fused to basal apodeme or mesosome, distally either trifid or sinuous. Genital sac present, without conspicuously rugose areas.

Female genitalia without bifid structure internally and without triangular processes laterally. Vulval margin concave, extended to very near distal end of abdomen, with medially interrupted row of typically very short setae (vms+vss?) and scattered microsetae (vss+vos?) in subgenital area. Subgenital plate with distal end reticulated. Subvulval plates present, small.