Navigator fossor ( Lea, 1914 ) Lea, 1914

Moeseneder, Christian H. & Hutchinson, Paul M., 2016, Navigator, a new endemic genus of Cetoniinae (Coleoptera: Scarabaeidae) from Australia, with descriptions of two new species and behavioural studies, Zootaxa 4173 (6), pp. 530-556 : 537-541

Navigator fossor ( Lea, 1914) new combination

( Figs. 1 G2, 1H, 2A, 3–5, 14C–D)

Pseudoclithria fossor: Lea 1914: 194 , plate 13, figs. 179–181; Schenkling 1921: 193; Cassis & Weir 1992: 448; Allard 1995: 143; Calder 2002; Golding 2009: 13; Krajcik 2012: 228.

Material examined (33 specimens). Lectotype, hereby designated, ♀ ( Fig. 3 ): AUSTRALIA: Mullewa, Western Australia, 25-034953 [SAM]. Condition: Missing: half of protarsomere 5 on right prothoracic leg, mesotarsomeres 2–5 on left mesothoracic leg, metatarsomere 5 on left metathoracic leg, metatarsomeres 4–5 on right metathoracic leg. Colour faded to black. Paralectotype, ♀: AUSTRALIA: Mullewa, Western Australia, Miss May, 25-039194 [SAM]. Condition: Missing: all tarsomeres on right prothoracic leg, all tarsomeres and inner spur on left metathoracic leg, femur, tibia and tarsomeres of right metathoracic leg.

Other material (21 males and 10 females) AUSTRALIA. Western Australia : 1 ♂, Billabong Roadhouse , 20.iii.2015, P. Hutchinson, CET 2152 [ PMH]; 1 Ƌ/ 1 ♀, 1 km N of Billabong Roadhouse , 1–3.i.2016, P. Hutchinson, CET2153, CET2154 [PMH]; 1 ♀, 1 km N of Billabong Roadhouse , 6.i.2016, P. Hutchinson, CET 2155 [ PMH] ; 1 ♀, 30 km S of Cue, 2.iii.2004, P. Hutchinson, CET 0186 [ PMH]; 1 Ƌ, Lake Barlee , 4.ii.2003, M.R. Golding, 5972 [MG]; 14 Ƌ/ 6 ♀, 10 km W of Menzies , 15.i.2013 / 16.i.2013 / 17.i.2013 / 12.i.2015, P. Hutchinson, CET1857, CET1859, CET0408 ( Fig. 5 ), CET1860 ( Fig. 4 ), CET1861, CET1862, CET1863, CET1864, CET1887, CET1888, CET2098, CET2101, MIC61103-001, MIC61103-002, MIC61103-003, MIC61103-004, MIC61103-005, MIC61103-006, MIC61181-001, CET61182- 002 [ MIC / PMH]; 2 Ƌ/ 1 ♀, Morawa [assumed Morowa] , 15.iv.1991 / 16.iv.1991, A Szito [ DAFWA]; 1 Ƌ, Mount Margeret district [assumed Mount Margaret, Western Australia area], T159396 [QM]; 1 Ƌ [ WAM].

Other evidence AUSTRALIA. Western Australia: adult remains in soil, 20 km S of Billabong Roadhouse , 19.iii.2015, P. Hutchinson [ PMH] ; adult remains in soil, 30.5 km S of Billabong Roadhouse , 20.iii.2015, P. Hutchinson, [ PMH] .

Diagnosis. Form: 14.8–18.9 mm, elongate-ovoid, dorsal surfaces coarsely punctate, often coalesced. Colour: black with green, blue, and purple metallic reflections. Head: clypeolateral declivity absent, clypeus widest preapically, clypeus apical margin linear, male antennal club enlarged. Elytron: posthumeral arch weakly sinuate, costae distinct, narrow. Abdomen: mesometasternal process undeveloped, female sternites distended with pygidium elevated and visible in dorsal view. Legs: female inner metatibial spur spatulate, metacoxa posterolateral angle acuate.

Redescription. Lectotype. Female ( Fig. 3 ). Length 18.6 mm, width 9.0 mm. Elongate-ovate. Head. Black. Clypeus: clypeolateral ridge divergent from antennal insertion ( Fig. 1 A, detail 1), widest pre-apically ( Fig. 1 A, detail 2); apical angle broadly arcuate to linear apex; lateral and apical declivity absent ( Fig. 1 A, cross-section 6 and detail 7); disc flat, gradually inclined to slightly raised lateral and apical margins ( Fig. 1 A, detail 4), bearing coarse, glabrous punctures. Frons with distinct low circular medial elevation; disc with coarse punctures, glabrous at base of ocular canthus. Ocular canthus bearing few short setae apically. Antenna: scape black, apically with few setae, posterior margin with brush of long, pale setae; pedicel black with brown apical margin; antennomeres 3–7 black, bearing few long, pale setae; club black, equal length to antennomeres 2–7, less than 0.5 x length of head; antennomere 8 internal surface with medial patch of short pale setae; antennomere 10 external surface brown on ventral two-thirds. Thorax. Pronotum black; basomedian margin linear; basolateral margin linear, slightly angled anteriorly; basolateral angle slightly obtuse, posterolateral margin linear, parallel, broadly arcuate post medially then attenuate to anterolateral angle; anterior margin concave sinuate; lateral margin bearing ridges; disc with coarse punctures, becoming rugulose at anterolateral angle; laterally bearing sparse pale microsetae. Scutellum black, elongate with broad base, coarsely punctate and glabrous. Elytron black; narrowly exposing mesepimeron; lateral margin parallel; weakly sinuate posthumeral arch barely exposing metacoxa, then broadly arcuate to apex; disc coarsely punctate, most coalesced and eroding margins of costae, bearing pale microsetae, denser in basal and lateral regions; humeral and apical umbones not distinctly raised; costae 1–4 distinct, narrow; sutural costa narrow with sutural apices obtusely angled. Mesometasternal process present as narrow, low, rounded elevation, declivous between mesocoxa, bearing sparse setae on declivity. Metasternum black; sparsely punctate, setose medially; rugulose laterally; bearing short, pale setae. Legs. Black. Profemur dorsoventrally flattened, weakly attenuate to apex; ventral surface moderately punctate, bearing sparse, long, pale setae. Protibia elongate, narrow, tridentate, denticles acute, equidistant, basal denticle shorter and premedial; dorsal surface with longitudinal rows of macropunctures, punctures smaller at base of denticles, clothed with few short pale setae, setal brush sparse. Protarsomeres 1–5 longer than tibial length, bearing few microsetae. Mesofemur dorsoventrally distinctly flattened, parallel; ventral surface sparsely punctate, bearing long, pale setae. Mesotibia elongate; ventral surface sparsely punctate, bearing short, pale setae; internal margin and dorsal surface sparsely clothed with long setae; external margin bearing a moderately-sized, acute medial denticle and a smaller, acute basal denticle; apex bispinose; spurs long parallel and tapering at apex. Mesotarsomeres 1–5 longer than tibial length, bearing few small, pale setae. Metafemur dorsoventrally distinctly flattened, elongate; anterior margin moderately arcuate; posterior margin linear; ventral surface sparsely punctate, bearing long, pale setae. Metatibia elongate, narrow, parallel; ventral surface with 2 longitudinal rows of punctures, bearing sparse, short, pale setae; internal margin and dorsal surface sparsely clothed with long, pale setae; external margin bearing small acute medial denticle ( Fig. 1 H, detail 2); apex trispinose ( Fig. 1 H, detail 3); external spur parallel sided with arcuate apex; internal spur broader, spatulate ( Fig. 1 H, detail 1), bilaterally expanded. Metatarsomeres 1–5 shorter than tibial length, bearing few black setae. Metacoxal posterolateral angle arcuate ( Fig. 1 G, detail 2). Abdomen. Sternites black; distinctly distended ( Fig. 1 E, detail 1); sternite 6 1.5 x length of sternite 5; sternites 2–5 glabrous medially, laterally with single row of sparse punctures, bearing long pale setae; sternite 6 evenly sparsely punctate setose. Pygidium black, 45º angle to body ( Fig. 1 E, detail 3), concentrically rugulose with centre at apex, bearing sparse, short, pale setae on disc and apically.

Variation in female specimens. Length 16.8–18.9 mm, width 7.9–9.1 mm. Head black with some green and dark purple reflections. Frons elevation low, indistinct. Thorax, pronotal posterolateral margin weakly concave, disc black with blue reflections along lateral margin. Scutellum dark blue. Elytra black with blue reflections along lateral declivity, exposing pygidium, costa 3 low, disjointed, indistinct. Metasternum dark-blue purple, densely punctate laterally. Legs black with blue reflections, apices of denticles with brown wash. Protibial basal denticle in some specimens reduced to obtuse angle or indistinct. Mesofemur ventral surface posterior margin rugulose. Metatibia with minute basal denticle. Sternites dark blue-purple. Pygidium dark blue-purple with large single puncture near basolateral angle.

Male ( Figs. 4 , 14 C). Based on all males in specimens examined list. Length 14.8–16.2 mm, width 6.7–7.9 mm. Differs from female lectotype in the following characters. Body more depressed. Head: metallic dark green or blue. Antennal club long, arcuate, longer than antennomeres 2–7, and as long as head. Thorax: Pronotum metallic dark green with blue reflections or dark blue with green reflections or black with dark blue reflections, basomedian margin slightly concave, lateral margin arcuate at midlength, then linear to anterolateral angles. Scutellum metallic blue. Elytron metallic blue, costae black, costa 3 low disjointed and indistinct to complete. Metasternum metallic blue with green and purple reflections, laterally bearing long pale pilosity. Legs: blue-purple or blue with green reflections. Tarsomeres black. Protibia narrower, basal denticle nodulate to obsolete. Mesotibial spurs long fine tapering. Metatibial basal denticle absent, external spur long fine tapering, internal spur long, parallel with apex acute. Metatarsomeres 1–5 longer than tibial length. Abdomen: Sternites metallic blue with green reflections, abdominal groove shallow along sternites 3–6 or indistinctly flattened; sternites 2–4 with row of sparse punctures bearing long, pale setae; sternites 5 and 6 with 1–2 rows of denser setose punctures. Pygidium metallic blue-purple with green reflections, 90º angle to body, concentrically rugose or bicentrically rugose with centres preapical to medial, bearing large puncture at basolateral angle. Genitalia ( Fig. 2 A). Phallobase narrowest at apex, broadest near base of parameres, 1.5 x length of parameres. Parameres narrow, parallel, gradually widening to apex; dorsal cleft basally broad and evenly arcuate attenuate to apex.

Differential diagnosis. Differs from N. ruficornis and N. interior by absence of clypeolateral declivity, metacoxa posterolateral angle arcuate. Differs from similar N. pixii in male metatibia without setose groove, from female by larger size and more elongate shape.

Remarks. From the two female specimens in the collection of the SAM, which are evidently syntypes (International Commission for Zoological Nomenclature 1999: Article 73.2), we designate the specimen labelled “Type” as the lectotype, which sets the specimen labelled “Cotype” as a paralectotype.

Ecology, development, and distribution. Before our study, only six specimens were known from collections and little had been reported on the natural history of N. fossor . Lea (1914) mentioned a male specimen that was collected from a spider web at Mullewa, and speculated, based on the amount of dirt carried by the holotype, that females dig, using the spurs as spades. Golding (2009) observed N. fossor flying low to the ground in the morning north of Mullewa, and Szito collected two males and one female on late flowering eucalypt in June 2013 (A. Szito, personal communication). Here we provide accounts of more recent field observations made of N. fossor by P.M.H. in the west-central region of Western Australia:

8–14 January 2013 —The previously known collecting localities of Morowa, Mullewa, and Lake Austin were visited but no specimens were encountered. Conditions were dry and temperatures ranged from 44–47 °C.

15 January 2013 —Two males were attracted to a light trap at dusk at a site 10 km west of Menzies ( Fig. 14 A) where the temperature had reached 42 °C and humidity was 80–90% after 80 mm of rainfall over the two preceding days as a result of cyclone Narelle. The habitat at the location was open intermittent mallee woodland with predominant Acacia understorey over red sand.

16 January 2013 —At the same site, approximately 10 males were observed in flight, no more than 20 cm above the ground, beneath and near clusters of Acacia species and Grevillea Brown ex Knight (Proteaceae) species ( Fig. 14 B). Due to the smaller size and the large antennae, males were easily differentiated from females. The beetles flew slowly, skilfully weaving amongst the thicket of attached and fallen branches, at times landing and walking with extended antennal clubs ( Fig. 14 C). They were not observed digging or encountering females. All adult specimens were captured.

Eleven larvae, and a single adult female, were also found at the site west of Menzies, while searching within a 20–30 mm thick decomposing layer of scarab-type faecal pellets and semi-matted decomposed leaf litter on damp, red sand located beneath cleared dead Acacia branches and a 50–70 mm layer of dry leaf litter ( Fig. 14 A, 14D). The larvae were transferred to a container for rearing.

17 January 2013 —Adult specimens were again observed at the site, including three females in flight (10:30– 11:30). Peak activity of males was from 12:00–12:45 with up to five at one time seen flying or walking on the ground. Observations made at the site indicate that adults fly between the hours of 10:00–15:00, and at dusk.

19 March 2013 —Further larvae were found at a site opposite the Billabong Roadhouse off the Northwest Coastal Highway in the Shark Bay district. The area, which was used as a car park, consisted of Acacia with little understorey, and standing water was present on the ground after recent rainfall. Excavation of leaf litter beneath three to four tall Acacia revealed a dry upper layer of 40 mm depth and, below it, a non-matted, decomposed 20 mm layer over hard red sand. A layer of scarab-type faecal pellets rested on the sand and five living larvae and the remains of two adults of N. fossor were found.

Various dates in 2013 —Approximately seven sites between Geraldton and Morowa and several sites up to 80 km south of Menzies were searched, often after heavy rainfalls, but no evidence of N. fossor was encountered.

3 January 2014 —Forty-five larvae were found at the site 10 km west of Menzies. Heavy rainfall had occurred in the area three days earlier.

March 2015 —Three larvae were collected from a site 1 km north of the Billabong Roadhouse after heavy rainfall from cyclone Olwyn. These larvae were reared in captivity, resulting in one male and two female adult specimens. Adult remains were found at sites located 20 km and 30 km to the south of the Roadhouse.

Natural history discussion. Navigator fossor adults have only been recorded once on flowers, at Morowa, Western Australia (Andy Szito, personal communication) when two males and one female were collected on late flowering Eucalyptus L'Héritier de Brutelle (Myrtaceae) . All other observations suggest that N. fossor is not a flower-visiting species, even when other cetoniines have been found in great numbers feeding on blooming trees and bushes nearby. West of Menzies, no specimens of N. fossor were observed on flowers during six visits from 2000–2012 from late January to the middle of February, despite large numbers of other cetoniines and buprestids feeding on flowering mallee ( Eucalyptus ) and Grevillea , which may indicate that adult N. fossor emergence is triggered by rainfall rather than blooming trees.

To N. fossor the dense debris of fallen and attached limbs in Acacia clusters and their decaying foliage provide protection against wind and water erosion of the substrate and allow a thick accumulation of mulch, composed mainly of dead leaves. Larvae and adults are well hidden in this habitat and have remained undiscovered, even in such locations as near the Billabong Roadhouse where coleopterists visit frequently. Several attempts were undertaken to attain adult N. fossor from field-collected larvae and pupae but these were mostly unsuccessful. One exception was a batch of 45 wild-collected larvae where 13 adult males and three adult females were found fully developed and alive when pupal cells were opened forcibly (to reduce loss). In all cases where collected larvae or pupal cells did not yield self-eclosing adults, these were found to be deceased and affected by mould when pupal cells were opened. In our study we did not observe or simulate conditions that triggered emergence. In captivity, pupation occurred as early as April and emergence in January of the following year. Pupal cells of females were noticeably larger than those of males.

Figures

FIGURE 1. Navigator characters. A—characters of the head (example N. pixii male): A 1 — margins laterally divergent, A 2 — head widest preapically, A 3 — shallow arcuate to linear anterior margin, A 4 — gradually inclined margins, A 5 — shallow preclypeus, A 6 — cross-section, A 7 — lateral declivity absent. B—characters of the head (example N. ruficornis female): B 1 — lateral declivity present, B 2 — deep preclypeus, B 3 — cross-section, B 4 — lateral declivity present. C—characters of the pronotum (example N. pixii male): C 1 — concave linear basolateral margin, C 2 — broad median angle of lateral margins, C 3 — coarsely punctate disc. D—characters of the elytra (example N. pixii male, except D 9): D 1 — weakly sinuate-linear posthumeral arch, D 2 — slightly exposed metacoxa, D 3 — elytral basal half parallel sided, D 4 — apical half of elytra broadly arcuate to apex, D 5 — slightly protruding mesepimeron, D 6 – 7 — indistinctly raised apical umbone, D 8 — visible pygidium D 9 — pygidium not well visible (example N. ruficornis). E—characters of the female abdomen: E 1 — distinctly convex and distended sternites, E 2 — pygidium in normal plane (example N. ruficornis), E 3 — pygidium in elevated plane (example N. pixii). F—character of the abdomen: F 1 — undeveloped mesometasternal process. G—metacoxa posterolateral angle: G 1 — angulate (examples N. pixii and N. ruficornis), G 2 — broadly arcuate (example N. fossor), G 3 — spinose (example N. interior). H – K: characters of the metatibia: H— Navigator fossor female: H 1 — spatulate internal spur, H 2 — unidentate, H 3 — trispinose apex. I— Navigator ruficornis female: I 1 — large, median denticle, I 2 — trispinose apex. J— Navigator interior female: J 1 — small, median denticle. K— Navigator pixii male: K 1 — unispinose apex. Note: cross-sections in A and B are from clypeal anterolateral angle to clypeolateral margin, not in transverse axis.

FIGURE 2. Navigator male aedeagi. A— Navigator fossor. B— Navigator pixii. C— Navigator ruficornis. Note: male N. interior are unknown.

FIGURE 3. Navigator fossor lectotype, female.

FIGURE 4. Navigator fossor male.

FIGURE 5. Navigator fossor female.

FIGURE 14. Navigator habitat. A – D— Navigator fossor (all images near or 10 km west of Menzies, Western Australia): A— Acacia leaf litter and branch thicket. B— Acacia with scattered Grevillea. C—male on leaf litter under Acacia. D—larva in decomposing leaf substrate. E – F— Navigator pixii (images at Boggomoss site BM 03, Queesland): E—collecting locations of adults and larvae. F—accumulations of dead leaves, predominantly from Acacia harpophylla, on the ground under which larvae were found.