Rigoutorum jakli 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 : 253-258

Rigoutorum jakli Hutchinson & Moeseneder , new species

( Figs 8–9 , 10B )

http://zoobank.org/NomenclaturalActs/ 698E17EC-7668-4476-81EA-AC7556D797E9

Diaphonia bacchusi: Golding 2009: 20 (left image—female, right image—male).

Type series (61 males, 4 females): Holotype male. 66.6 km N. of Bullfinch W.A., 1. Feb. 2000, P. Hutchinson, Diaphonia bacchusi flying over Acacia , [genitalia on card]; CET 0380 [ WAM] . Paratypes. 1 male: Marloo Stn Wurarga W.A., 1931–1941, A. Goerling, EB 32, GJB, Diaphonia bacchusi n. sp. J. Rigout det. 1996 PARATYPE, [genitalia on card] [paratype of Diaphonia bacchusi ]; [ NHML]. 1 female: Marloo Stn. Wurarga W.A., 1931–1941, A. Goerling, C.S.I.R.O; [ NHML]. 7 males: 30 km W. Kirkalocka Stn. WA., 16:1:[19]89, M. Powell, Active over Acacia, Golding /Powell Collection donated 12. Feb. 2002; [ WAM], AFBRC 8465-01, 8465-02 [ AFBRC]. 6 males: 3 km W of [White] Wells Hstd, W.A., 24-1-98, Bequeathed H. Demarz Coll.; AFBRC 8463-01, 8463-02, 8463-03, 8463-04, 8463-05, 8463-06 [ AFBRC]. 2 males: Paynes Find Rd W.A., 24-1-1998, H. Demarz; AFBRC 8462-01, 8462-02 [ AFBRC]. 7 males: 24 k[m] E. of Pindar W.A., 26-1-[19]92, Golding/Powell Collection donated 12. Feb. 2002; [ WAM], AFBRC 8464-01, 8464-02, 8464-03 [ AFBRC]. 2 males: 53 km NW. Mt. Magnet W.A., 18:1:[19]93, Golding, Powell, active over sandplain, Golding/Powell Collection donated 12. Feb. 2002; [ WAM]. 3 males: Paynes Find Rd N. of Wubin W.A., 24. Jan. 1998, H. DeMarz [sic], Pseudoclithria flying around Acacia CET 0387, 0389, 0392 [ PMH]. 2 males: 13.0 km E. of L.[ake] Mongers (Perenjori-Wanarra Rd) W. Aust., 27. Jan. 2000, P. Hutchinson, Diaphonia bacchusi flying over Euc[alyptus]; CET 0384, 0386 [genitalia on card] [ PMH]. 1 female: L[ake] Deborah N. Bullfinch West. Aust., 31. Jan. 2000, P. Hutchinson, found dead saltlake, CET 0381 [ PMH]; [ WAM]. 1 female: 44.8 km N. Bullfinch West. Aust., 31. Jan. 2000, M. Peterson, Diaphonia bacchusi dead edge saltlake; CET 0382 [ PMH]. 1 male: 66.6 km N. of Bullfinch W.A., 1. Feb. 2000, P. Hutchinson, Diaphonia bacchusi flying over Acacia ; CET 0383 [genitalia on card] [ PMH]. 2 males: 86 km NNE of Wubin W.A., 27. Jan. 2004, P. Hutchinson, Diaphonia flying; CET 0388 [ PMH], AFBRC 8383-01 [ AFBRC]. 15 males: 61 km NNE of Wubin West. Aust., 29. Jan. 2005, P. Hutchinson, Diaphonia bacchusi flying over heath; CET 2621, 2622, 2627, 2628, 2629, 2630, 0400, 0401, 0403, 0404, 0405, 0406 [ PMH], MIC61016-001, 61016-002, AFBRC 8382-01 [ AFBRC]. 2 males: Grt. N. Hwy. 61 km N. Wubin West. Aust., 30. Jan. 2005, P. Hutchinson; CET 2623, 2624 [ PMH]. 1 female: 18 km E. of Grt. N. Hwy on Kalannie Rd. West. Aust., 3. Feb. 2006, P. Hutchinson, Diaphonia bacchusi on eucalyptus leaves; CET 0385 [ PMH]. 8 males: Goodlands Rd., 25km SE Grt. N. Hwy (60 km N. Wubin) West. Aust., 11. Feb. 2009, P. Hutchinson; CET 2619, 2620, 2625, 2626, 2631, 2632, 2633, 2634 [ PMH]. 2 males: Lake Baladjie N.R. WA., 20. Dec. 2012 - 19. Jan. 2013, T.M. Hanlon, Blue bucket trap; CET 2162, 2163 [ PMH].

Description. Holotype Male ( Figs. 8 , 10B ). Length 15.5 mm, width 8.16 mm, widest at humeral umbone. Ovate, depressed. Head. Black. Clypeus quadrate (length:width ratio 1:1), reflexed at apex, clypeolateral ridge present from antennal insertions high, linear, parallel-sided, angulate to anterolateral angles and continuous across slightly sinuate anterior margin. Lateral declivity deep in apical half, striolate; apical declivity deep and micropunctate, both angulate and visible in dorsal view. Disc flat, abruptly inclined to highly elevated clypeolateral and apical ridge. Surface coarsely punctate, bearing very long, yellow pilosity. Clypeofrontal suture absent. Frons flat, with coarse punctures bearing dense, very long, yellow pilosity. Ocular canthus narrow, bearing short, yellow setae. Antennae with scape black and apex brown, elongate, bearing few, short, pale setae along dorsum of length, dorsum of apex bearing long, black setae, posterior margin bearing dense setal brush of long, yellow pilosity. Pedicel black, apex brown bearing sparse, pale microsetae. Antennomere 3 elongate, same length as antennomeres 4 and 5 combined. Antennomeres 3–7 black with apices dark brown and bearing sparse, long, pale setae. Club dark brown, length of antennomeres 2–7, 0.25 x length of head. Antennomere 8 internal surface bearing setae along dorsal surface in apical half. Antennomere 10 external surface dark brown with ventral third light brown. Thorax. Pronotum black with wide (¼ width) brown maculae laterally along entire margin encircling small black macula at midlength. Transverse with basomedian margin arcuate, basolateral margin linear and angled anteriorly. Basolateral angle narrowly arcuate through 90°. Posterolateral margin linear, slightly attenuate to broadly arcuate midlength then linear attenuate to anterolateral angles. Anterior margin linear. Lateral margins bearing ridges. Disc with sparse micropunctures becoming larger to all margins, rugulose along lateral margins bearing sparse, long, pale pilosity. Scutellum black, equilateral triangle with coarse punctures except along midline, bearing long, pale pilosity. Elytra yellow-brown, sutural costa dark brown-black, lateral margins narrowly dark brown. Mesepimeron narrowly exposed, with base of elytra laterally pronounced. Posthumeral arch linear in dorsal view, arcuate in lateral view, weakly exposing metacoxa, obscured by pilosity, then slightly attenuate to broadly arcuate apex. Disc (interstices 1 and 2) coarsely punctate in weakly-defined rows becoming coalesced, then rugulose at apical declivity, laterad to costa 2 rugulose; bearing long pale setae. Humeral and apical umbones raised. Costa 1 broadest, costa 2 narrower, costa 3 barely recognizable. Sutural costa parallel basally, raised and attenuate in apical half with apices truncate. Mesometasternal process black, broad, flat with broadly arcuate apex, declivous at anterior margin of mesocoxa; surface impunctate, glabrous with apical declivity bearing dense, very long, yellow pilosity. Metasternum black, medially with moderately sparse punctation, laterally rugulose bearing long, yellow pilosity. Mesepimeron and metepisternum black, rugulose bearing long, yellow pilosity, metepimeron black and impunctate. Legs. Black with dark brown suffusions. Profemora dorsoventrally flattened, slightly attenuate to apex with ventral surface rugulose bearing yellow pilosity. Protibiae elongate parallel, unidentate with apical denticle elongate acute; dorsal surface with medial and internal row of coarse punctures bearing sparse, long, pale setae and setal brush composed of moderately dense, short, ginger setae; spur stout, not reaching apex of tarsomere 1. Protarsomeres 1–5 slightly longer than tibial length; tarsomere 5 longest, 2 x length of tarsomere 4. Tarsomeres 1–5 bearing setae less than half tarsomere length. Protarsal claws long, simple and symmetrical. Mesofemora dorsoventrally flattened, parallel with ventral surface rugulose bearing very long, yellow pilosity. Mesotibiae elongate, ventral surface medially with 2 rows of coarse punctures bearing short, yellow setae in basal half. Internal margin basally bearing sparse, short, pale setae. External margin basally evenly arcuate, angulate mid-length, concave apically, non-denticulate, apex bispinose with spines acute and external spine longer. Internal surface bearing rows of very long, yellow pilosity. Spurs narrow, attenuate with acute apex, reaching midlength of mesotarsomere 2. Mesotarsomeres 1–5 longer than tibial length. Tarsomere 5 longest, 2 x length of tarsomere 4. Mesotarsomeres 1–4 bearing setae half tarsomere length. Mesotarsal claws long, simple and symmetrical. Metacoxae black, posterolateral angle 90°, surface rugulose, bearing long, yellow pilosity. Metafemora dorsoventrally flattened with anterior margin arcuate and posterior margin linear. Ventral surface medially sparsely punctate, rugulose along margins bearing very long, pale pilosity. Metatibiae elongate, ventral surface with row of coarse punctures along internal margin and rugulose adjacent to external margin bearing sparse, long, yellow pilosity. Internal margin bearing sparse, short, yellow setae. External margin medially with low, very obtuse angle, non-denticulate, glabrous. Dorsal surface bearing dense, very long, yellow pilosity. Metatibial apex bispinose with internal spine short, truncate and external spine broad, truncate. Spurs parallel, apex acute, internal spur broader and longer reaching apex of tarsomere 2. Metatarsomeres 1–5 equal to tibial length; tarsomere 5 longest, 2 x length of tarsomere 4. Tarsomeres 1–4 bearing setae half of tarsomere length. Claws long, simple and symmetrical. Abdomen. Sternites black. Sternites 2–6 medially with broad shallow depression, concave in lateral view, with row of sparse punctures bearing short, pale setae and laterally with dense punctures bearing long, yellow pilosity. Sternite 7 medially impunctate and glabrous, laterally rugulose bearing long, yellow pilosity. Propygidium bearing long, yellow pilosity. Pygidium dark yellow with apex broadly black and base narrowly black extending medially to disc. Pygidium length:width ratio 1:1.5, angulate in lateral view, with a narrow, arcuate, slightly obtuse angle post midlength; surface concentrically rugulose with centre post midlength bearing sparse, short, pale setae at apex and basolateral angles. Genitalia ( Fig. 10B ). Phallobase widest at apex, attenuate to and narrowest at base near parameres, dorsal surface with a longitudinal deep groove and 2.15 x length of parameres. Parameres narrow, external margin sinuate concave medially, arcuate to apex. Each paramere narrowing to midlength, divergent to pre-apex then attenuate to apex. Dorsal cleft 45° at base, then broad, ovate in basal two-thirds, apically attenuate to where parameres meet. Paramere in lateral view arcuate through obtuse angle at basal third; surface sparsely punctate.

Variation in males. Length: 12.5–17.8 mm, width 6.5–9.4 mm. Antennomeres 3–7 mostly brown. Pronotum with lateral maculation at anterior and posterior ends traversing towards midline or reduced in small specimens to posterolateral margins. Disc with evenly spread macropunctures and lacking micropunctures. Elytral apices microspinose. Sutural maculation expanded at midlength then laterally covering apical declivity. Protibiae external margin bisinuate or bidentate. Mesotibiae external margin unidentate or bidentate. Metatibiae external margin bearing obtuse denticle. Pygidium black maculation not medially extended.

Female ( Fig. 9 ). Description based on CET0381 [PMH] (Lake Deborah, 40 km NE of Bullfinch, Western Australia). Differs from male in the following characters. Length: 18.9 mm, width 10.0 mm. Stout, broader and deeper. Head. Anterior margin weakly arcuate convex. Clypeal disc slightly elevated along midline, sparsely microsetose. Frons sparsely microsetose basolaterally. Antennal scape black with antennomere 10 external surface with ventral quarter brown. Dorsum of scape glabrous. Pedicel glabrous. Antennal club slightly shorter than antennomeres 2–7. Thorax. Pronotum uniformly black. Basomedian margin sinuate. Basolateral angle more broadly arcuate through 90°. Lateral margin broadly arcuate at midlength. Pronotum micropunctate medially becoming macropunctate and rugulose laterally. Pronotal and metasternal setae ash-grey to black. Elytra. Black, setae black. Posthumeral arch sinuate in lateral view, distinctly exposing metacoxa. Humeral and apical umbones slightly raised. Costae weaklydefined, barely visible. Metepimeron rugulose bearing yellow pilosity. Legs. Black. Protibiae broader and tridentate. Denticles long, acute, medial denticle at midlength and closest to basal denticle. Dorsal surface internal half with coarse, denser punctures. Mesotibiae ventral surface with punctures restricted to basal half; external margin midlength bearing robust, acute denticle with smaller basal denticle, concave post midlength; apex divergent with spines broad. Mesotarsomeres 1–5 same length as tibia. Metatibiae external margin bearing acute or truncate denticle at midlength; apex divergent. Metatibial spurs parallel with apices arcuate, dorsal spur surpassing apex of metatarsomere 2. Metatarsomeres 1–5 shorter than tibial length. Abdomen dark brown. Sternites convex. Sternite 6 medially with 2 rows of punctures bearing long setae. Sternite 7 medially along posterior half densely micropunctate. Pygidium black; length:width ratio 1:1.8. In lateral view broadly arcuate angle post midlength. Setose across base.

Variation in females. Length 15.1–18.9 mm, width 7.6–10.0 mm. Head with anterior margin linear. Antennomeres 1–10 brown. Elytra dark brown. Legs dark brown. Pygidium with 2 lateral, oblique, elliptical yellow maculae.

Diagnosis. Rigoutorum jakli can be recognised by its pronotal sculpturing consisting of an impunctate region on the disc, surrounded with micropunctation and radiating outwards, replaced by spaced macropunctures that bear long pilosity. The pronotum in males is shiny black to anterior margins with lateral yellow maculation (rarely complete in minor males), one-quarter width of pronotum, usually extending from basal to anterior margins. Females are uniformly black.

Differential diagnosis. Rigoutorum jakli is similar to R. bacchusi but differs in having a shiny pronotum with impunctate disc surrounded with micropunctures, then spaced macropunctures.

Discussion. Most of the specimens are consistent morphologically and in colour with a few beetles exhibiting unusual variation (e.g. bidentate protibiae, expanded elytral maculation). The following are noteworthy. Specimens from the northwest of the range of the species (53 km north-west of Mount Magnet, 30 km west of Kirkalocka Station) lack pronotal micropunctures surrounding the impunctate region on the disc; these are replaced by spaced macropunctures. All four specimens examined from Kirkalocka have a bisinuate protibial external margin, and bidentate mesotibial external margin.

Natural history. Rigoutorum jakli are found in mallee ( Eucalyptus ) heath on yellow sandplains with dominant large plants mainly consisting of Eucalyptus, Allocasuarina, Acacia and Melaleuca (Myrtaceae) . Adults are localised, and males are encountered in flight. Only three specimens were seen on flowers, namely Eucalyptus , even though plants were flowering nearby. Males regularly flew at the top of taller plants ( Eucalyptus, Allocasuarina, Acacia ) at a height of 1.8–3.7 m. They frequently flew to a neighbouring plant where they circled the top once or twice and then proceeded to the next tree. The behaviour was then repeated. We assume that males were searching for females. Adult males were never noticed flying low to the ground or with a female. Populations of over 100 individuals were observed.

On 27 January 2004, along the Wannara-Perenjori track, 2 km west of the Great Northern Highway, where many males were seen circling the tops of mallee, a single male was observed entering a hole in the ground beside a mallee ( Eucalyptus ). Only one female was found alive, perched on leaves of a Eucalyptus . No males were observed nearby.

Adults have been recorded from 13 January to 11 February (based on data from specimens and PMH trip diaries). Two specimens from Lake Baladjie Nature Reserve, caught in a bucket trap, have label data showing a collection date from 20 December to 19 January.

In several instances, specimens were located dead on the edge of salt lakes (“strandlines”). In years when rain fills the salt lakes, individuals may be washed into the lake or land on the lake and drown. In these cases, salt lakes act as natural pitfall traps, and can be used as an indicator of the presence of some local fauna. Strandline specimens deteriorate rapidly due to predation and the detrimental effects of salt and sun. However, if collected within a few days, these effects are minimal, and specimens can be assumed as recently deceased.

Etymology. This species is named in honour of Mr. Stanislav (Stan) Jákl (Prague, Czech Republic), an intrepid and prolific researcher of Cetoniinae and Dynastinae. Stan suggested that the specimens that PMH captured north of Wubin, Western Australia may represent an undescribed species.

Figures

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.