Rigoutorum bacchusi Hutchinson & Moeseneder & Mitchell 2022, new combination
Creators: name: Hutchinson, Paul M.
name: Moeseneder, Christian H.
name: Mitchell, Andrew
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Scarabaeidae
Rigoutorum
Rigoutorum bacchusi

description: Rigoutorum bacchusi (Rigout & Allard, 1997) new combination
(Figs 4–6, 10A)
Diaphonia bacchusi Rigout & Allard, 1997: 26–27, dorsal image, aedeagus. Holotype male NHML. Type locality: Southern Cross, Western Australia.
Diaphonia bacchusi: Calder 2002; Golding 2009: 20 (centre image); Hutchinson & Moeseneder 2013: 2; Hutchinson & Moeseneder 2019: 279; Moeseneder et al. 2019: 545.
Specimens examined (57 males, 2 females). Holotype. Male: Southern Cross, W.A., H.W. Brown, Diaphonia bacchusi n. sp. J. Rigout det. 1996 TYPE, Dysdiatheta minima n. sp M.E. Bacchus det, National Museum of Victoria Melbourne, [genitalia on card]; [NHML]. Other specimens examined. 1 male: Yellowdine, WA, 2. Feb. 1970, Ex Carnaby Coll., Diaphonia bacchusi male Rigout & Allard det. T.A. Weir 2016; [WAM]. 1 male: E. Hyden, WA., 26-1-75, Pseudoclithria ruficornis, Bequeathed, H. Demarz Coll.; AFBRC8455-01 [AFBRC]. 9 males: 50 km S. Coolgardie W. Australia, 2. i. 1977, A.M & M.J. Douglas leg. ABFF, Pseudoclithria ruficornis (Westwd.) det. R.M. Young 1989; 88/3007, 88/3008, 88/3009, 88/3010, 88/3011, 88/3012, 88/3013, 88/3014, 88/3015 [WAM]. 4 males: 57 km. E. Hyden W.A. Cruising, 10-2-[19]91, G.P, Golding/Powell Collection donated 12. Feb. 2002; [WAM], AFRBC8459-01, 8459-02 [AFBRC]. 4 males: Yellowdine, W.A., 16-1-1992, male, Donated 2015, Jack Hasenpusch, Aust. Insect Farm; AFBRC8456-01, 8456-02, 8456-03, 8456-04 [AFBRC]. 2 males: E. Sth. Cross, W.A., 22-1-1993, H. Demarz, Pseudoclithria ruficornis male, Donated 2015, Jack Hasenpusch, Aust. Insect Farm; AF- BRC8457-01, 8457-02 [AFBRC]. 1 male: 21 km S. of Yellowdine West. Aust., 28. Jan. 1997, P.H. Pseudoclithria; CET 2164 [PMH]. 1 male: 29 km S. of Lake King W. Aust., 1. Feb. 1999, dead, salt lake, Golding/Powell Collection donated 12. Feb. 2002; [WAM]. 6 males: 104 km E. of Lake King W.A., 3. Feb. 1999, P. Hutchinson, Flying over Euc.[alyptus]; CET 0393 [genitalia on card], 0395, 0397, 0398, 0399 [PMH], AFBRC8460-01 [AFBRC]. 1 male: 9 km SSE Peak Eleanora Upper Lort River W. Aust., 5. Feb. 2000, dead, salt river edge, Golding/Knowles, Golding/ Powell Collection donated 12. feb. 2002; [WAM]. 2 males: L. Hurlstone, W.A., 6.3.2000, dead; AFBRC8458-01, 8458-02 [AFBRC]. 1 male: 53.4 km s. of Southern Cross West. Aust., 30. Jan. 2004, P. Hutchinson, Diaphonia flying over heath; CET 0394 [genitalia on card] [PMH]. 1 male: Grt. E. Hwy. 33 km E. of Yellowdine W. Aust., 5. Feb. 2006, P. Hutchinson; CET 2638 [PMH]. 1 male: Lake King (strandline) West. Aust., 21. Feb. 2006, P. Hutchinson, Diaphonia bacchusi dead lake edge; CET 0391 [genitalia on card] [PMH]. 2 males: 6 km N of Yellowdine, WA, 23 Jan. 2009, TM & LM Hanlon, On Acacia sp leaves; AFBRC8313-01, 8381-01 [AFBRC]. 1 male: Grt. E. Hwy. 35 km E. of Yellowdine W. Aust., 12. Feb. 2009, P. Hutchinson; CET 2639 [PMH]. 2 males: Lake King, W.A., 14 Feb 2011, P. Hutchinson & C. Moeseneder, salt lake, dead on strandline; MIC61002-005, 61002-006 [AFBRC]. 1 male: 26 km S. of Menzies W.A., 26. Jan. 2012, M. Hanlon & M. Powell on mallee flowers; CET 2164 [PMH]. 2 males: Ghooli, E. of Southern Cross W. Aust., 15. Jan. 2013, P. Hutchinson, Diaphonia bacchusi 0930-1045 hrs flying over plants; CET 0409, 1318 [PMH]. 7 males: Ghooli, E. of Southern Cross W. Aust., 15. Jan. 2013, P. Hutchinson, Diaphonia bacchusi 1045 -1110 hrs flying over plants; CET 1199, 1380, 2635, 2636, 2637 [PMH], MIC61102-001, 61102-002 [AFBRC]. 1 male: 10 km W. Yellowdine Rd. Hs. West. Aust., 26. Jan. 2016, P. Hutchinson, Diaphonia bacchusi dead Male; SCAR135-D4, CET 2203 [PMH], AFBRC8380-01 [AFBRC]. 2 males: Karalee Pumping Station West. Aust., 27. Jan. 2016, P. Hutchinson, Diaphonia bacchusi 0915-0945 [hrs] flying over Acacia; CET 2201, 2202 [PMH]. 1 female: Karalee Pumping Station West. Aust., 27. Jan. 2016, P. Hutchinson, Diaphonia bacchusi 8 ft. high on Acacia 0945 [hrs]; CET 2302 [PMH]. 1 male: Karalee Pumping Station West. Aust., 27. Jan. 2016, P. Hutchinson, Diaphonia bacchusi 1000 -1030 [hrs] on Acacia; CET 2200 [genitalia on card] [PMH]. 1 male: Karalee Pumping Station West. Aust., 27. Jan. 2016, P. Hutchinson, Diaphonia bacchusi 1000 -1030 on Allocasuarina; CET 2213 [genitalia on card] [PMH]. 1 male: Southern Cross W.A., H.W. Brown, E.F. DuBoulay Collection, Pseudoclithria ruficornis (Westwd.) det. R.M. Young 1989; 88/3016 [WAM]. 1 female: Tammin, W.A., H.W. Brown; AF- BRC8461-01 [AFBRC].
Redescription. Holotype Male (Figs 4, 10A). Condition: right antennal club and one protarsomere 5 missing, one protarsomere 5 attached to metasternum. Length 16.9 mm, width 8.5 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 dense, 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, elongate, along dorsum of length bearing few, short, pale setae and dorsum of apex bearing long, black setae, posterior margin bearing dense setal brush of long, yellow pilosity. Pedicel black 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 3–7, 0.3 x length of head. Antennomere 8 on internal surface bearing setae medially. Antennomere 10 external surface dark brown-black. Thorax. Pronotum black with narrow brown maculae laterally along posterolateral margin. 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 ridged. Disc with evenly dense, moderately coarse punctures becoming rugulose over majority of surface, bearing dense, long, yellow pilosity. Scutellum black, equilateral triangle with coarse punctures except along midline, bearing long, pale pilosity. Elytra yellow-brown, sutural costa 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 visible. Sutural costa parallel basally, raised and attenuate in apical half with apices bearing a minute spine. 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 dense punctation, laterally rugulose bearing long, yellow pilosity. Mesepimeron, metepisternum and metepimeron black, rugulose, bearing long, yellow pilosity. Legs. Black. 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, reaching apex of tarsomere 1. Protarsomeres 1–5 equal to tibial length; tarsomere 5 long and 2 x length of tarsomere 4. Protarsomeres 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 and basal half of external margin bearing sparse, short, pale setae. Dorsal surface bearing dense, very long, yellow pilosity. External margin evenly arcuate, non-denticulate, apex bispinose. Internal spine short, acute; external spine long, acute. Spurs long, narrow, attenuate with an acute apex to middle of mesotarsomere 2. Mesotarsomeres 1–5 longer than tibial length. Mesotarsomere 5 longest, 2 x length of tarsomere 4. Mesotarsomeres 1–4 bearing setae equal to 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 weakly arcuate and posterior margin linear. Ventral surface medially sparsely punctate, rugulose along margins bearing very long, pale pilosity. Metatibiae elongate with ventral surface rugulose bearing 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, acute and external spine broad, sinuate. Spurs parallel, apex acute, reaching apex of tarsomere 2. Metatarsomeres 1–5 equal to tibial length; tarsomere 5 longest, 2 x length of tarsomere 4. Metatarsomeres 1–4 bearing setae equal to tarsomere length, with tarsomeres 1–2 bearing setae 1.5–2 x tarsomere length. Claws long, simple and symmetrical. Abdomen. Sternites black. Sternites 2–6 medially with broad, shallow depression, concave in lateral view, with sparse row of 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 1:1.75, angulate in lateral view, with a narrow, arcuate, slightly obtuse angle post midlength; surface concentrically rugulose with centre past midlength bearing sparse, short, pale setae at apex and basolateral angles. Genitalia (Fig. 10A). Phallobase widest at apex, attenuate to and narrowest at base near parameres, 2 x length of parameres, dorsal surface with a longitudinal, deep groove. 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 90° at basal third; surface sparsely punctate.
Variation in males (Fig. 5). Length: 13.5–17.5 mm; width: 7.1–9.0 mm. Antennomere 10 external surface with ventral quarter brown. Pronotal basolateral angle rounded. Pronotal lateral maculation absent. Elytra with suture black, not extending to sutural costa. Apical spine absent. Mesotibial external margin angulate pre midlength; internal surface bearing long, yellow pilosity. Metatibial external margin evenly arcuate or serrate. Pygidium with black basal and apical maculation joining medially, enclosing 2 lateral, oblique, elliptical, yellow maculae.
Female (Fig. 6). Description based on CET2302 [PMH] (Karalee, 45 km east of Southern Cross). Differs from male by the following characters. Length 16.3 mm, width 8.9 mm. Stouter, broader and deeper. Head. Antennal scape along dorsal length glabrous. Thorax. Pronotum without lateral yellow macula. Basolateral angle arcuate, slightly obtuse. Elytron. Black. Margins narrowly exposing sternites laterally. Legs. Femoral and tibial ventral surfaces bearing black pilosity. Protibiae stout, tridentate, each denticle long and acute with denticle 2 at midlength and closest to basal denticle; setal brush composed of long, black setae. Mesotibial external margin with acute denticle at midlength; apical spines broad, internal spine acute, external spine truncate; spurs reaching apex of mesotarsomere 2. Mesotarsomeres equal to length of tibia; tarsomeres 1–2 bearing setae 2 x length of tarsomere. Metatibial internal and external margins bearing sparse, long pilosity. External margin with short, truncate denticle at midlength. Apical spines broad, truncate. Spurs broad, parallel, internal spur broadest preapically with apex arcuate, reaching midlength of tarsomere 3. Abdomen. Sternites convex. Sternite 6 bearing long, black pilosity across posterior half. Pygidium black. Obtusely arcuate in lateral view.
Variation in females. Length 17.2 mm, width 9.0 mm. Femora and tibial surfaces bearing yellow-brown pilosity. Protibial setal brush composed of long, yellow-brown setae. Sternites 5 and 6 bearing long, yellow-brown pilosity across posterior half. Pygidium dark purple-black.
Diagnosis. Rigoutorum bacchusi can be recognised by its pronotal sculpture that consists of uniformly dense punctation that bears dense, long pilosity. The colour is dull black with or without a lateral, narrow, yellow maculation (less than one sixth width of pronotum) and restricted to basal half. The lateral maculation is absent in females.
Differential diagnosis. Rigoutorum bacchusi is similar to R. jakli but differs in having a duller pronotum with uniformly medium-sized and adjacent punctures. Males are with or without narrow, yellow maculation along the basal half of the lateral margin.
Natural history. Rigoutorum bacchusi occur in mallee heath on yellow sandplain with dominant large trees, specifically Eucalyptus (Myrtaceae), Allocasuarina (Casuarinaceae) and Acacia (Fabaceae). Only one specimen was seen on Eucalyptus flowers, even though plants were in bloom nearby, but most were seen flying at the top of taller plants in mallee 1.8–3.6 m high. The beetles circled the top of the tree or bush once or twice and then flew to the next plant, repeating the behaviour. We assume that males were searching for females, but males were never observed flying low to the ground or with a female. Two females of this species are known. One of these was seen at a height of 2.4 m on a 3 m tall, fine-leafed Acacia at 0945 at Karalee Pumping Station. From 0915–0945 approximately 10 males were seen flying over adjacent Eucalyptus, Allocasuarina and Acacia but they were not seen to approach the female. Between 1000–1030 conditions changed, with the weather turning cloudy, and the males stopped flying. Two males were later found on Acacia foliage and one male on Allocasuarina foliage.
On 15 January 2013 at 1.5 km south of Ghooli (Fig. 7), many males were observed exhibiting the same behaviour as described above. The beetles were in flight, along a remnant roadside vegetation strip on yellow sand, bordering large areas of farmland. Several plants were examined around their base for signs of larvae, larval faecal droppings or adult remains. Leaf and bark litter beside a mallee (Eucalyptus) was removed, revealing cetoniine larval faecal droppings at no more than 30 cm from the tree trunk and beneath the mulch. One medium-sized and one large larva, assumed to be at L2 and L3 stages, were uncovered along with remains of an adult female beetle, which was retained. Larvae were also retained and transferred to rearing boxes, but these did not develop to adults. Adults were observed from 2 January to 12 February, based on specimen data and PMH trip diaries.
description: Published as part of 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, pp. 239-259 in Zootaxa 5150 (2) on pages 247-253, DOI: 10.11646/zootaxa.5150.2.4, http://zenodo.org/record/6621254