Xixuthrus lansbergei subsp. michael Missori & Ercoli 2018, ssp. nov.

Xixuthrus lansbergei michael, ssp. nov.

Type material. Holotype: male, Lufa, Eastern Highlands Province, Papua New Guinea, 1980, unknown collector (Fig. 1A) (presently stored in Paolo Missori’s collection).

The images of another specimen with the same features (about 100 mm) collected in the same area from the Jimi River (1990, Papua New Guinea) has been shown us by Anton Kozlov (deposited in an undetermined private collection).

Description. Colour. reddish-brown.

Length. Total, including mandible: 103.74 mm; pronotum + elytron: 85.05 mm.

Head. Large, covered with short dense golden hairs; distance between eyes: 7.21 mm. A wide and deep impression from vertex to between antennal tubercles. Clypeus in dorsal view, triangular-shaped; in anterior view, rounded-flat, coarsely punctate with short, sparse, yellow setae (Fig. 2 A).

Mandible. Strong, robust, elongate, and coarsely punctate with microreticulate. The lateral edge has a concave groove, which resembles the wavy blade-form of a kris knife (a hallmark of Xixuthrus lansbergei; Lameere, 1912).

Antenna. Reaching backwards about 2/3 of elytra length. The antennal scape not attaining pronotum, gradually and slightly enlarged apically, covered with distinct, irregularly spaced shallow punctures.

Pronotum. Surface coarsely, deeply punctate, covered with short gold pubescence. At base as wide as elytra, sides divergent rearwards (max. width: 28 mm), dentate along lateral margin with small, not-sharpened spinules, with a slender spine on the posterior angles. In the middle, a sharp, deep triangular impression is covered with pubescence.

Scutellum. Brown with dark edges, oval, transverse, minutely punctured.

Prosternal apophysis. Broad on the base with sharp apex.

Elytron. Surface coarsely, deeply punctate, covered with very short gold pubescence and flanged lateral margin. Width at about half length: 33 mm. Four slightly raised costae never attaining the apical end, with few intercostal bridges on the distal side. Tips of elytra conjointly rounded, with a small ridge at the apex of each elytron (Fig. 3A). The fifth intercostal space oblique compared to others.

Legs. Forelegs longer than mid-legs, thin and covered along the internal margin with short dense spinules. Fore basitarsi longer than broad, covered dorsally with short hairs, without bristles on the lateral edges (Figs. 4A and 5A). First tarsomere as long as 2/3 of the second and third together; the length of the second and third tarsomeres 1/10 greater than width. Tarsal claws long and pointed. Hind legs smoother, rugosely punctate on the lateral margin.

Abdomen. Very sparsely pubescent.

Diagnosis. This new subspecies X. lansbergei michael ssp. nov. resembles X. lansbergei (Lameere, 1912) described from Bougainville Island but differs in having elongated and little hairy fore tarsi with long tarsal claws, rounded-flat clypeus, elytra covered by short pubescence, and elytral apex rounded with a small ridge.

Xixuthrus lansbergei (Lameere, 1912) male in our own collection from Bougainville Island (Fig. 1b) is 86.02 mm long. Clypeus in anterior view as a sloping roof (Fig. 2b). The elytra covered with long pubescence, the tips J-curve shaped, the fifth intercostal space almost perpendicular, with a sharp ridge at the apex of each elytron (Fig. 3b). Fore tarsomere short, the width of the second and third tarsomeres 1/10 greater than length, covered on the dorsolateral surface by long gold–orange hairs (Fig. 4b); curled and long bristles on the lateral edges of the second and third tarsomeres (Fig. 5b); tarsomere 5 (onychium) thick and short, length of first and second tarsomeres together, with long hairs beneath the surface; tarsal claws short and stocky. Other different characters have been considered normal variations in the Xixuthrus specimens (e.g., anterior leg length, thorax shape, first antennomer length).

Etymology. This subspecies is named for Mount Michael (3750 m), in the Lufa District of the Eastern Highlands Province, where the beetle presumably lives. The mountain takes its name from Michael James (Mick) Leahy (1901–1979), gold prospector and explorer and the first European to discover the Highlands area of Papua New Guinea.