Eurylychnus dyschirioides ( Castelnau, 1867 )

Lay, Stuart, 2023, A taxonomic review of the Australian genus Eurylychnus Bates (Coleoptera: Carabidae: Broscini), Zootaxa 5330 (2), pp. 247-264 : 253-256

Eurylychnus dyschirioides ( Castelnau, 1867)

( Figs 1A , 3A , 5A–C , 6 )

Maoria dyschirioides Castelnau, 1867: 78–79 . Britton 1949: 538 (clarification of type locality). Moore et al. 1987: 121 (catalogue). Häckel et al. 2010: 66 (checklist).

Eurylychnus olliffi Bates, 1891: 286 . Synonymised by Sloane 1911: 825. Type locality: Mt Kosciusko, NSW.

Type material: Syntype Maoria dyschirioides : dyschirioides Cast. n.g. [handwritten] // dyschirioide Cast. [handwritten, black label border] // Crooked Riv. N.Zelanda. [Crooked River is erroneously listed as being in New Zealand, instead of Victoria, Australia ( Britton 1949)] Coll.Castelnau [handwritten and typed, black label border] // TYPUS [typed in red, red label border] ( MCG) [examined photographs]. Syntype Maoria dyschirioides from Crooked River, VIC in the Howitt collection, Melbourne Museum, not examined. Syntype (s) Eurylychnus olliffi, Mt Kosciusko, NSW , in the Museum of Natural History Paris, not examined.

Other material examined (38): New South Wales: (1), Brindabellas , 20.i.1996, M.S. Roesler & A. Polak ( ANIC); (1) , Collector , under log, 28.xii.1977, D.P. Carne ( ANIC); (2) , 5 miles [8km] east of Gundaroo , 7.v.1975, B.P. Moore ( ANIC); (1) , Hazelgrove, F.H. Taylor ( ANIC); (1) , Kiandra , 26.i.1963, B.P. Moore ( ANIC); (1) , 36.22S 148.24E, Kosciusko NP, 3.4km NE Guthega , 1580m, 18.xii.1986, A. Newton & M. Thayer ( ANIC); (1) , Kosciusko , ii.1926, H.C ( ANIC); (5) [1 ♁, 4 unknown sex], Marulan , 25.ii.1962, B.P. Moore ( ANIC); (1) , Mogo , 23.v.1944, A. McA ( ANIC); (1) , Monga , xii.2005 ( ANIC); (1) , Monga State Forest , 28.i.1988, B.P. Moore ( ANIC); (1) [♁], Mount Kosciusko , 25.ii.1960, B.P. Moore ( ANIC); (1) , ‘ Ooyella’, Collector , 6.x.1987, B.P. Moore ( ANIC); (3) , Rules Pt [Rules Point], ii.1924, H.J. Carter ( ANIC); (1) , 16km NW of Thredbo, Little Thredbo Homestead , 31.xii.1979, E.B. Britton ( ANIC); (1) , Tinderry Mountains , 30.x.1960, B.P. Moore ( ANIC); (1) , Toomah R., iii.1927, H.G.C ( ANIC) ;

Australian Capital Territory: (1), Blundell’s , 25.iv.1961, B.P. Moore ( ANIC); (1) , Mount Franklin , 30.iii.1963, B.P. Moore ( ANIC); (2) , Mount Franklin , under log, 28.xii.1979, D.P. Carne ( ANIC); (1) , Ginini Flats , 18.ii.1976, B.P. Moore ( ANIC); (1) , 35.42S 149.00E Namadgi NP, Brandy Flat Hut Track (S. end), 28.ix.2001, J. Balderson ( ANIC); (1) , 35°39’50S 149°59’14E Namadgi NP, Orroral Valley , 9–12.ix.1997, M. Neave & S. Grosse ( ANIC); (1) , Piccadilly Circus , 30.iii.1963, B.P. Moore ( ANIC); (1) , Piccadilly Circus, Brindabella Range , 29.x.1982 ( ANIC) ;

Victoria: (1), Bonang , 22.ii.1960, B.P. Moore ( ANIC); (1) , Mount Torbreck , 1.xii.2021, S. Lay ( SLC); (1) [♁], Tarra Valley , 23.xii.1962, B.P. Moore ( ANIC); (1) , 36.38S, 147.06E, 14km SW of Tawonga , 4.iii.1971, S. Misko ( ANIC); (1) , Wingan Inlet NP, 23.v.1978, S. & J. Peck ( ANIC) .

Diagnosis: Eurylychnus dyschirioides is a widespread species with a range that overlaps with E. blagravei , but the smaller body length of E. dyschirioides (<13.3mm) along with the presence of paramedian setae on ventrites 3–5 make it easy to recognise. Eurylychnus dyschirioides closely resembles E. ovipennis , however E. dyschirioides can be separated by its red legs, stronger elytral striae, transverse impression behind the eyes being punctate ( Fig. 3A ) and by the apex of the aedeagus median lobe having a broad tooth ventrally.

Redescription: Body shiny black, legs red, sometimes dark red; antennae and palps piceous. Body length 10.1–13.3mm; maximum pronotum width 3.3–4.5mm; maximum elytra width 3.8–5.1mm.

Head: Vertex covered in reticulation of very fine meshes. Transverse impression behind the eyes strongly to moderately defined and usually distinctly punctate. Frontal impressions beginning at the eyes, with or without obsolescent impressions posteriorly that unite with transverse impression behind the eyes; frontal impressions curve inwards and join the frontoclypeal suture, continuing down the clypeus where they end in a seta before the anterior margin. Clypeus straight to weakly emarginate. Labrum weakly emarginate, with 6 evenly spaced setae of even length along the anterior dorsal margin. Eyes with 1 supraorbital seta each. Mandibles with a seta in the scrobe. Mentum tooth bifid, with a short seta either side basally; paramedian foveae present; lobes squarish with broad rounded corners. Submentum with 6 setae. Stipes with 2 setae, the inner being more than double the length of the outer. Gula weakly to moderately convex, with dense transverse wrinkles, especially posteriorly; gular sutures with small gular pits.

Thorax: Pronotum covered in reticulation of very fine meshes; foveae present adjacent to basal angles; base of the pronotum with a broad weak impression, sometimes weakly punctate, connected laterally to the pronotal foveae at the basal angles, its anterior margin sloping gently upwards, meeting the median impression; posterior margins strongly rounded from posterior 1/3 to basal margins, with tubercles on basal angles; pronotum widest at approximately the midline; lateral margins with 3–5 setae, the posterior most setae distant from the posterior angles while the anterior most setae are near to the anterior angles; median impression strong, not extending to anterior margin, ending posteriorly at the beginning of broad basal impression; pronotal carina borders the lateral margins from the beginning of the anterior margins, to just past the basal tubercles on the basal angles. Prosternum convex and smooth, anterior margin with a raised border. Protrochanters with 2 close setae. Males with squamose setae under protarsomeres 1–3 ( Fig. 1A ). Metatrochanters with a small seta. Mesocoxae and metacoxae both with 2 setae.

Elytra: Elytral disc flat, convex laterally, oval; covered in reticulation of fine meshes, sometimes confined to the edges of each interstice in the apical half of the elytra; lateral elytral carina extended from the humerus to apex. Parascutellar striole fused with apical portion of stria 1. Elytra with 7 striae, striae 1–4 strongly defined, striae 5–6 less pronounced and stria 7 almost indistinct; striae 5 begins on humeral angle; interstices weakly convex; striae usually smooth, rarely with weak irregular punctures. Basal groove with 3 obsolete asetose punctures either side of the suture. Humerus raised, extending inwards from the basal groove, forming a short transverse ridge.

Abdomen: Ventrites 3–6 each with a pair of paramedian setae.

Male genitalia: Aedeagus left paramere ( Fig. 5A ) broad, asetose, constricting dorsally at the apex to form a short broad denticle; right paramere ( Fig. 5B ) long, thin, constricted in apical half to form a long denticle with a blunt apex, short setae present along the ventral margin of the apical half, extending onto the dorsal margins at the apex and along the middle of the paramere from the apex to the beginning of the constriction. Median lobe ( Fig. 5C ) moderately curved ventrally, deflected to the right; apex rounded, sometimes tapered, with a distinctive broad tooth ventrally.

Figures

FIGURE 1. Ventral surface of male protarsi of A, Eurylychnus dyschirioides; B, Eurylychnus cylindricus.

FIGURE 3. Dorsal habitus of A, Eurylychnus dyschirioides; B, Eurylychnus ovipennis; C, Eurylychnus kershawi; D, Eurylychnus femoralis. Scalebars are 2mm.

FIGURE 5. Male genitalia of Eurylychnus dyschirioides (A–C):A, left paramere, B, right paramere, C, median lobe left lateral; E. ovipennis (D–F): D, left paramere, E, right paramere, F, median lobe left lateral; E. kershawi (G–I): G, left paramere, H, right paramere, I, median lobe left lateral; E. femoralis (J–L): J, left paramere, K, right paramere, L, median lobe left lateral. Scale bars are 0.5mm.

FIGURE 6. Pronotum of Eurylychnus dyschirioides. PC = pronotal carina; PS = pronotal setae; MI = median impression; PF = pronotal fovea; PT = pronotal tubercle. Scalebar is 1mm.