Semanopterus kingstoni Reid & Tees, 2023

Reid, Chris A. M. & Tees, Natalie A., 2023, A new, but possibly extinct, species of Semanopterus Hope, 1847 from Lord Howe Island, in the southwestern Pacific Ocean (Coleoptera: Scarabaeidae: Dynastinae), Zootaxa 5306 (5), pp. 563-570 : 564-567

Semanopterus kingstoni Reid & Tees , new species

( Figs 1–10 )

Type. Holotype female. AUSTRALIA, LORD HOWE ISLAND: Mt Gower LHI, / 700m pitfall, / 30.1.1979 [handwritten label by T. Kingston]; Lord Howe I., N.S.W. / leaf litter / Mt Gower / T. Kingston / Date 30-1-79 [printed label, except date handwritten by unknown person]; K188798 [printed]; HOLOTYPE / Semanopterus ♀ / kingstoni Reid & Tees [‘Holotype’ printed]. The holotype is deposited in the entomology collection of the Australian Museum (Sydney, Australia).

Description. The holotype is slightly damaged: right apical maxillary and labial palpomeres, left protarsomeres 2–5, right protarsus, left mesotarsomeres 3–5, right mesotarsomeres 4–5, metatarsomeres 4–5 missing; right antenna removed and mounted on a point.

Body convex ( Figs 1–2 ), robust; dark reddish brown, anterior and basal margins of pronotum, scutellum, elytral suture, pygidium and apical abdominal ventrite almost black, venter, femora and antennae paler reddish brown, membrane between abdominal ventrites 5 and 6 orange; dorsal surface shiny; length 27 mm, pronotal width 10.5 mm, elytral width 13.5 mm.

Head ( Figs 3–5 ). Frons rugulose, sculpture shallower and sparser than clypeus; ocular canthi rugulose and laterally setose, slightly bulging anterior to eyes; Clypeus transverse, trapezoidal, apical width less than half basal width, anterior edge truncate and medially reflexed, surface transversely rugulose; frontoclypeal suture distinct, transverse, with small symmetrical median tubercle; eye reniform, dorsal part slightly smaller than ventral part; antenna with 9 antennomeres, 1 scyphiform, 2–6 transverse, 5–6 triangular, 7–9 forming a tight transversely oval club with 7 widest; width of club slightly greater than length of antennomeres 2–6; antennomeres 1–2 punctured with long setae, 3–6 glabrous, 7–9 with scattered punctures and short recumbent setae; mandible laterally rounded, projecting laterally and apically beyond clypeal margin, densely laterally punctured and setose; maxilla laterally exposed, including base of palp; apical maxillary palpomere elongate cylindrical, length about 3x width and about 1.5x length of preapical palpomere, which is slightly shorter than preceding palpomere; galea with large elongate triangular apical tooth, visible below mandibular apex; base of labial palpi hidden by side of mentum; mentum laterally expanded and longitudinally arched at middle, narrowing to bifurcate apex, surface closely rugosely punctured and setose.

Thorax ( Figs 1–3 , 7–10 ). Pronotum transverse, width 1.5x length, and greatest width about 1/3 from base, with almost straight basal margin, evenly rounded lateral margins, rounded posterior angles, rounded but slightly produced anterior angles, and truncate anterior margin; margins strongly raised laterally, anteriorly shallow raised with inner margin narrowly triangular at midline, basal margin not raised except at sides; anterior edge membranous; pronotal disc convex, with narrow elongate depression in basal half of midline and a few scattered small dimples laterally; disc sparsely and finely punctate, except elongate depression with larger, denser, C-shaped punctures, anterior and basal margins finely and densely punctured; prothoracic hypomeron densely rugosely punctured and setose; prosternum smooth and almost impunctate anterior to coxae, at middle convexly produced and strongly elevated with dense punctures and setae; postcoxal lobe truncate in ventral view, elongate triangular in posterior view, strongly punctured and setose; scutellum transversely semi-oval, sparsely micropunctured; elytra apparently fused but with distinct suture, slightly abbreviated with rounded apices, reaching basal margin of propygidium; elytral disc almost non-striate, four irregular lines of punctures present but obscured by similarly sized and spaced interstrial punctures; sutural margin slightly elevated and impunctate, and two similar low ridges on disc; epipleuron setose at base only, apical half undefined; mesoventrite densely punctured and setose; mesocoxae adjacent; wing reduced to a short broad lobe, less than 0.2x elytral length (not visible under elytra in posterior view); metaventrite finely and sparsely punctured, laterally setose, medially glabrous, abbreviated, shorter than mesoventrite on midline and about equal to length of metacoxa laterally; protibial anterior surface with row of large punctures and setae, outer margin tridentate, denticles equidistant, distal strongly curved, proximal small and obtuse; protibial spur long and flat; mesotibiae and metatibiae with a single lateral oblique ridge of short spines and setae and dorsal margin with irregularly serrate ridge; metafemur oval, longer than wide, stout, laterally with rows of setose punctures on dorsal edge and near ventral margin; metatibia abruptly expanded in apical third to truncate apex, latter with dense row of acute setae (mostly broken); length of metatibial inner spur about 1.5x outer spur, both broad and almost straight; metatarsomere 1 asymmetrically triangular, width almost equal to length, without lateral carina.

Abdomen ( Figs 2 , 7, 10 ). Propygidium slightly convex in lateral view, as long as pygidium, without stridulatory files, disc evenly sculptured with mixture of large setose punctures, dense micropunctures and microreticulation; pygidium evenly shallowly convex, glabrous, disc sparsely micropunctate, dense at base and lateral margins, thick apical ridge with a few setae (most broken off); ventrite 1 punctured and setose throughout, ventrites 2–4 with dense large and small punctures and setae at sides and base, almost impunctate and glabrous at middle, ventrite 5 similar but also transverse row of large punctures and setae near posterior margin; membrane between ventrites 5 and 6 expanded, about half length of ventrite 5; ventrite 6 anteriorly densely micropunctate and punctate, with scattered setae, posterior margin with weakly defined raised edge. Genitalia not examined.

Etymology. Named for Tim Kingston, the collector of this species.

Notes. The new species is placed in Semanopterus because it best fits most of the diagnostic features of this genus, as described by Carne (1957), Endrödi (1985), and Weir et al. (2019): body reddish brown to black; frontoclypeal suture armed with low tubercle; clypeus broadly triangular or trapezoidal, with sides straight and anterior edge upturned; head without vertically flattened area; mandibles strongly exposed beside and beyond clypeus; apical maxillary palpomere not enlarged; maxillae with galeae strongly developed, conspicuously toothed; apical labial palp cylindrical; mentum not dilated, not covering bases of maxillary palpi; elytra with odd numbered intervals costate; elytra without tubercle near scutellum; protibia tridentate; apex of metatibia truncate, with many spiniform setae; metatarsomere 1 without distinct longitudinal external carina; propygidium not enlarged, without stridulatory ridges; last ventrite of female with transverse sulcus.

Semanopterus kingstoni differs from all other species of this genus by: convex body; distinct frontoclypeal suture; antennae with 9 antennomeres; pronotal disc with single fovea, in basal half; pronotal basal angles rounded and basal border absent medially; epipleura indistinct apically and with setae confined to base; protibiae bluntly tridentate; metatibia with a single oblique setose ridge. This combination of characters easily distinguishes S. kingstoni from all other species in the genus. It might, therefore, be argued that S. kingstoni should be placed in a new genus. However, the convexity, loss of anterior pronotal fovea and loss or reduction of borders and margins on pronotum and elytra, may all be linked to loss of flight. Furthermore, variation in the number of antennomeres is not regarded as significant at generic rank in the Dynastinae and is widespread in dynastine genera as currently understood ( Carne 1957).

Figures

FIGURES 1–6. Semanopterus kingstoni new species, holotype. 1, dorsal habitus; 2, lateral habitus; 3, dorsal of head; 4, anterior of head; 5, antenna; 6, labels.

FIGURES 7–10. Semanopterus kingstoni new species, holotype. 7, ventral habitus; 8, prothoracic leg; 9, metathoracic leg; 10, posterior.