Rigoutorum Hutchinson & Moeseneder, 2022

Hutchinson, Paul M., Moeseneder, Christian H. & Mitchell, Andrew, 2022, Rigoutorum a new genus for Diaphonia bacchusi Rigout and Allard (Coleoptera: Scarabaeidae: Cetoniinae: Schizorhinini), with description of a second species from Western Australia and notes on habitats and behaviours, Zootaxa 5150 (2), pp. 239-259 : 243-244

Genus Rigoutorum Hutchinson & Moeseneder , new genus

( Figs 4–6 , 8–10 )

http://zoobank.org/NomenclaturalActs/0b3827fe-945e-4a1d-aafb-38e61a5ff30e

Type species: Diaphonia bacchusi Rigout & Allard, 1997: 26 ; here designated.

Included species: Diaphonia bacchusi Rigout & Allard, 1997 ; Rigoutorum jakli new species

Description. Length 12.5–18.9 mm. Form elongate ovate. Colour black (females) or brown with yellow elytra and maculation (males). Head. Clypeus quadrate, lateral margins divergent, parallel in apical half, widest apically; clypeolateral ridges present, parallel, anterior margin linear sinuate medially; margins abruptly inclined to high elevations; disc coarsely punctate. Frons coarsely punctate. Antennal club not enlarged in male, same length as antennomeres 2–7. Thorax. Pronotum transverse trapezoidal; basomedian margin weakly concave-linear; lateral margins with broad median angles; disc punctate. Scutellum base broad, elongate, coarsely punctate. Elytron with posthumeral arch linear (in dorsal view), slightly exposing metacoxa, then slightly convergent to broad arcuate apex; mesepimeron slightly exposed; humeral and apical umbones indistinctly raised; sutural costa distinct, each elytron with one complete, indistinct, low costa; disc punctate in irregular lines. Mesometasternal process undeveloped, present as low parallel process, declivous at anterior margin of mesocoxae. Legs. Protibiae unidentate, denticle elongate; protarsomeres elongate and simple. Mesotibiae broadest in basal half, not bidentate or weakly bidentate, concave in apical half. Mesotarsomeres elongate and simple. Metafemora elongate, anterior margin arcuate. Metatibiae elongate, narrow, parallel in apical half, angulate to weakly denticulate at mid-length; spurs elongate parallel, broader in females. Metatarsomeres elongate and simple. Abdomen. Sternites distinctly concave in males, convex in females. Metasternum sparsely punctate medially, rugulose laterally. Pygidium concentrically rugulose. Genitalia ( Fig. 10 ). Phallobase to paramere length ratio 2:1, phallobase widest at apex with narrow, deep medial longitudinal groove on dorsal surface, parameres narrowing from base; sinuate concave widening near apex; dorsal cleft basally acute, narrowly ovate in basal half, then attenuate to apex.

Differential diagnosis. The following combination of characters distinguishes Rigoutorum from other genera of Schizorhinini. Size 12.5–18.9 mm; clypeus quadrate with clypeolateral margins abruptly and highly elevated; anterior margin linear; antennal club not enlarged, same length as antennomeres 2–7; head and pronotum punctatesetose; male protibiae unidentate; mesometasternal process undeveloped. Table 2 provides distinguishing characters among Rigoutorum , Diaphonia and Aurum Hutchinson & Moeseneder, 2019 .

Specimens examined: Rigoutorum bacchusi ; Rigoutorum jakli new species; Aurum leonorensis ; Diaphonia dispar ; Diaphonia xanthopyga ; Diaphonia melanopyga Lea, 1914 ; Diaphonia luteola ; Diaphonia vicina ; Diaphonia notabilis White, 1846 ; Diaphonia antoinei Allard, 1995 ; Diaphonia lateralis Blackburn, 1894 .

Remarks. In Moeseneder et al. (2019), Rigoutorum keys out at couplet 42 “ Diaphonia bacchusi … Diaphonia Newman (part)”. In Krikken (2018), Rigoutorum keys out at couplet 21 “ Diaphonia and Chondropyga ”. Hutchinson & Moeseneder (2019) give differential characters of Aphanesthes , Aurum , Chondropyga Newman, 1840 , Diaphonia , Diaphonia bacchusi and Diaphonia kerleyi Rigout & Allard, 1997 .

This study is our first step towards addressing the complex relationships among Diaphonia , Aphanesthes , Hemichnoodes , Pseudoclithria and Metallesthes . Mitchell et al. (2020) noted that “While the sampled species in this group are well defined, extensive further work is required to understand the relationships between these species and the status of the five current genera.”

Natural history. Behaviourally, Rigoutorum belongs in the non-flower-visiting group of Australian Schizorhinina genera where males are usually seen in flight and females are sedentary and rarely observed. This is also the case in Aurum , Diaphonia , Pseudoclithria , Grandaustralis Hutchinson & Moeseneder, 2013 , Navigator Moeseneder & Hutchinson, 2016, and Tapinoschema Thomson, 1880 . The flower-visiting group of genera are mostly found congregating on flowers with males and females in similar numbers and both sexes having similar-sized antennae (e.g. Metallesthes , Hemichnoodes , Aphanesthes ) ( Hutchinson & Moeseneder 2013, 2019; Moeseneder et al. 2014, 2019; Moeseneder & Hutchinson 2016). Aurum and Rigoutorum new genus constitute a subset of the former group in which male antennal clubs are not enlarged.

Etymology. The genus is named in honour of the Rigout family. Jacques Rigout contributed to the taxonomy of Batocerini ( Coleoptera : Cerambycidae ), Cetoniini and Schizorhinini (Cetoniinae), describing numerous new species. The Rigout family travelled to New Guinea researching Schizorhinini. Lydia Rigout operated Hillside Books.

Figures

FIGURE 4. Rigoutorum bacchusi holotype male. Scale in A = 5 mm, applies to A–E. F—specimen labels.

FIGURE 5: Rigoutorum bacchusi. Specimen CET2213 [PMH]. Karalee Pumping Station, Western Australia, Australia. Scale in A = 5 mm, applies to A–E. F—live specimen, G—head dorsal, H—head side view.

FIGURE 6. Rigoutorum bacchusi female. Specimen CET2302 [PMH], Karalee, 45 km east of Southern Cross, Western Australia, Australia. Scale in A = 5 mm, applies to A–E. F—head dorsal, G—head side view.

FIGURE 8. Rigoutorum jakli, male. Scale in A = 5 mm, applies to A–E. F, Specimen labels.

FIGURE 9. Rigoutorum jakli paratype female. Specimen CET0381 [PMH]. Scale in A = 5 mm, applies to A–E. F, Specimen labels; G, head dorsal; H, head side view.

FIGURE 10. Rigoutorum male genitalia. A, R. bacchusi; B, R. jakli.