Eurylychnus regularis Sloane, 1911

Lay, Stuart, 2023, A taxonomic review of the Australian genus Eurylychnus Bates (Coleoptera: Carabidae: Broscini), Zootaxa 5330 (2), pp. 247-264 : 261-262

Eurylychnus regularis Sloane, 1911

( Figs 2C , 4G–I )

Eurylychnus regularis Sloane, 1911: 824–825 . Moore et al. 1987: 121 (catalogue). Häckel et al. 2010: 65 (checklist).

Type material: Holotype: Eurylychnus regularis Sl. Id. By T. G. Sloane [handwritten and typed] // Type [typed] // Dorrigo 9.7.10 [handwritten] // Eurylychnus regularis Sl. HOLOTYPE PJD [red label, handwritten and typed] ( ANIC) .

Other material examined (20): New South Wales: (1), Dorrigo , 3.xi.1959, B.P. Moore ( ANIC); (2) , Dorrigo, W. Heron ( ANIC); (1) , Ebor , 15.i.12, R.N.T ( ANIC); (7) , 8 miles [13km] north of Ebor , 27.xi.1968, Turnbull ( ANIC); (1) [♁], Ebor scrub, 1.xii.1963, B.P. Moore ( ANIC); (1) [♁], New England NP, 10.i.1963, B.P. Moore ( ANIC); (3) , New England NP, 1.xii.1963, B.P. Moore ( ANIC); (1) [♁], New England NP, Point Lookout , 20.i.2020, S. Lay ( SLC); (3) [1 ♁, 1 ♀, 1 unknown sex], New England NP, Point Lookout , 19.i.2020, S. Lay ( SLC) .

Diagnosis: Eurylychnus regularis resembles E. blagravei , but differs by having 8 elytral striae, with striae 5 beginning at the humeral angle. Furthermore, the constriction of the posterior angles of the pronotum is less pronounced in E. regularis than E. blagravei ( Fig. 2C ). Eurylychnus regularis is sympatric with E. ovipennis , but the considerably larger body length (<18.1mm) of E. regularis , along with the sides of the pronotum having only 1 seta allow it to be differentiated.

Redescription: Body shiny black, legs black, with tibiae and tarsi sometimes reddish-black, mouthparts and antennae black. Body length 18.1–20.8mm; pronotum maximum width 5.5–6.1mm; elytra maximum width 6.0– 6.8mm.

Head:Vertex covered in sparse minute micropunctures.Transverse impression behind eyes weakly to moderately formed. Frontal impressions curving inwards, meeting frontoclypeal suture at tentorial pits and continuing along clypeus, ending in a seta before the anterior margin. Clypeus straight to weakly emarginated. Labrum anterior margin weakly to moderately emarginated, with 6 evenly spaced setae on the dorsal anterior margin, the outer 2 setae slightly longer than the inner 4. Eyes with 1 supraorbital seta each. Mandibles with a seta in the scrobe. Mentum median tooth broad, short and bifid, with a seta each side of the base; paramedian foveae present; lobes broad and usually round, but sometimes squarish with rounded corners. Submentum with 2 setae. Stipes with 2 setae each, with the inner seta being double the length of the outer seta. Gula weakly to moderately convex with some transverse wrinkles; gular sutures with small gular pits.

Thorax: Pronotum covered with sparse minute micropunctures, becoming reticulation of fine meshes on lateral margins; sometimes with transverse wrinkles from median impression; foveae present just above the basal angles; margins constricted posteriorly from basal 1/3; lacking tubercles on margins of basal angles; pronotum widest at, or slightly above midline, with 1 seta each side on the lateral margins at approximately the midline; median impression running most of the length of the pronotum; pronotal carina borders the lateral margins, extending onto the beginning of the anterior margins and terminating posteriorly at the foveae on the basal angles. Prosternum convex, sometimes with some fine wrinkles, with a raised border on anterior margin. Protrochanters with 1 seta. Male protarsi without any squamose setae on ventral surface. Metatrochanters lacking a seta. Mesocoxae with 1 seta on lateral margin. Metacoxae with 1 seta on anterior margin.

Elytra: Elytral disc convex and oval; covered with reticulation of fine meshes in apical half, confined to the edges of each interstice in basal half; lateral elytral carina extending from apex to humerus. Parascutellar striole isolated or partially connected to stria 1. Elytra with 8 strongly distinct striae; striae 3 and 4 converging or sub-parallel basally and stria 5 begins on the humeral angle; interstices slightly raised and convex; striae without obsolete punctures. Basal groove usually with 3 obsolete asetose punctures either side of suture, occasionally without punctures. Humerus simple.

Abdomen: Ventrites 3–5 lacking setae. Apical margin of ventrite 6 with a pair of paramedian setae.

Male genitalia: Aedeagus left paramere ( Fig. 4G ) broad, asetose, constricting apically from dorsal margin to form a long denticle for ¼ of its length; right paramere ( Fig. 4H ) long, narrow, gently tapering from half its length to form a pointed apex, with long setae present on the apical half of the ventral margin. Median lobe ( Fig. 4I ) weakly to moderately curved ventrally, moderately to strongly deflected to the right; apex blunt and rounded.

Figures

FIGURE 2. Dorsal habitus of A, Eurylychnus blagravei; B, Eurylychnus cylindricus; C, Eurylychnus regularis; D, Eurylychnus victoriae. Scalebars are 2mm.

FIGURE 4. Male genitalia of Eurylychnus blagravei (A–C): A, left paramere, B, right paramere, C, median lobe left lateral; E. cylindricus (D–F): D, left paramere, E, right paramere, F, median lobe left lateral; E. regularis (G–I): G, left paramere, H, right paramere, I, median lobe left lateral; E. victoriae (J–L): J, left paramere, K, right paramere, L, median lobe left lateral. Scale bars are 0.5mm.