Aphanocephalus occidentalis, Szawaryn, 2025

Aphanocephalus occidentalis sp. nov.

urn:lsid:zoobank.org:act:E61B81C1-6052-411D-82BF-B3DC590AFF1F

( Figs 8E, F View FIGURE 8 , 12G–I View FIGURE 12 )

Material examined. Type material.

Holotype. WESTERN AUSTRALIA: male, " 16.22S 125.12E WA CALM Site 25/2 Charnley River , 2km SW Rolly Hill, Jan. 1989 N. McKenzie / Berlesate ANIC 1273 closed forest litter" ( ANIC) GoogleMaps . Paratypes. WESTERN AUSTRALIA: " 16.22 S 125.12 E CALM Site 25/2 Charnley River, 2km SW Rolly Hill, W.A. 16-29 June 1988 I.D. Naumann / Berlesate ANIC 1083 closed forest litter" (1, ANIC); "W. AUSTRALIA Millstream 9-10/4/1971 N. R. Mitchell " (1, ANIC) GoogleMaps .

Other material. WESTERN AUSTRALIA: Oobagooma via Derby, WA, 28.xi.2002, S. Kniveton / light trap (1, ANIC) .

Type locality. Western Australia, North Kimberley .

Distribution. Western Australia ( Fig. 16 View FIGURE 16 ).

Etymology. Specific epithet derived from the Latin adjective “occidentalis ” meaning Western.

Diagnosis. Aphanocephalus occidentalis , with its almost entirely brown dorsal coloration (except for the paler lateral margins of the pronotum and humeral areas of the elytra) and rounded, spherical body shape, is quite unique among Australian species. It is also a distinctive species inhabiting Western Australia. Only in the very northeastern part of Western Australia might it co-occur with A. potamophilus . However, A. potamophilus differs in having a more elongated body outline and a less spherical shape. Its dorsal coloration is predominantly rufous, sometimes featuring a brown sutural line extending into a central elytral rhomboid macula. Additionally, A. occidentalis displays nearly uniform punctation on the pronotum, while A. potamophilus has double punctation, with larger and coarser punctae in the posterior corners of the pronotum. The male genitalia are similar between the two species. In both, the penis guide in inner view narrows towards a truncate apex. However, in lateral view, the inner margin of the tegmen in A. occidentalis is almost straight ( Fig. 12H View FIGURE 12 ), whereas in A. potamophilus , it is distinctly sinuate ( Fig. 13E View FIGURE 13 ).

Description. Length: 1.71 mm, width: 1.43 mm. Body elongate oval about 1.2 times as long as wide ( Fig. 8E View FIGURE 8 ), convex in lateral view ( Fig. 8F View FIGURE 8 ). Pronotum and elytra covered with long, dense setae. Head, pronotum and elytra dark brown, only antero-lateral margins of pronotum and antero-lateral margins of elytra paler, ventral side light brown to brown, antennae, mouthparts and legs yellow.

Pronotum covered with punctae of single size, only laterally punctae slightly coarser. Lateral margins of pronotum bordered, anterior margin without bordering line. Elytra covered with punctae of two sizes, uniformly intermixed. Pronotum and elytra explanate laterally, margins well visible throughout. Lateral sides of elytra broadly rounded, without pseudopores. Epipleuron with shallow sub-marginal furrow.

Mentum without lateral carinae. Labial palps separated by narrow carina. Prosternum with notosternal carinae absent; prosternal process with lateral carinae absent. Metaventrite longer than ventrite 1. Ventrite 1 longer than ventrites 2–4 combined. Ventrite 1 entirely covered with large punctae; ventrites 2–5 covered with punctae of two sizes, coarser at base forming a single row, and smaller on the rest of surface.

Male genitalia. Tegmen in inner view with sides rounded in middle, slightly tapering toward apex in apical part, apically broadly truncate, with a few short setae at apex ( Fig. 12I View FIGURE 12 ); in lateral view broad at base, sub-triangular in apical part, pointed at apex, outer margin slightly rounded, inner margin almost straight, only weakly sinusoidal in middle ( Fig. 12H View FIGURE 12 ). Penis long, broadening toward apex, outer margin straight in basal 3/4 and roundly curved in apical fourth, inner margin apically sinuate; gonopore about as long as wide, with apex at the same level as apex of penis, apically truncate; outer margin of gonopore with blunt hook ( Fig. 12G View FIGURE 12 ).

Female genitalia not examined.