Eurylychnus ovipennis Sloane, 1915

Lay, Stuart, 2023, A taxonomic review of the Australian genus Eurylychnus Bates (Coleoptera: Carabidae: Broscini), Zootaxa 5330 (2), pp. 247-264 : 259-260

Eurylychnus ovipennis Sloane, 1915

( Figs 3B , 5D–F )

Eurylychnus ovipennis Sloane, 1915: 444–445 . Moore et al. 1987: 121 (catalogue). Häckel et al. 2010: 66 (checklist).

Type material: Holotype: [in 2 pieces, abdomen pinned and prothorax card mounted, missing head] Dorrigo, 30.10.11., R.J.T. [handwritten] // type [typed] // Eurylychnus ovipennis Sl. Id. By T.G. Sloane [mix of handwritten and typed] // E. ovipennis Sl. HOLOTYPE PJD [red label, mix of handwritten and typed]; prothorax, point mounted with red label handwritten: Evidently proth. of E.ovipennis PJD Type ( ANIC) .

Other material examined (8): New South Wales: (1), 30 mi [les] [48km] east of Armidale , 8.x.1955 ( ANIC); (1) , Dorrigo, W. Heron ( ANIC); (1) , Barrington Tops State Forest, W.N. W Gloucester, Moppy Lookout Rest Area , under logs in rainforest, 3.ii.1982, G & T Williams ( ANIC); (2) [2 ♁], Barrington Tops NP, Wild Turkey Road 12.ii.2022, S. Lay ( SLC); (1) , Barrington Tops , 25.xii.1963, B.P. Moore ( ANIC); (2) [1 ♁, 1 ♀], New England NP, 1.xii.1963, B.P. Moore ( ANIC) .

Diagnosis: Eurylychnus ovipennis closely resembles E. dyschirioides , but E. ovipennis is less robust in form, has elytral striae that are less strongly defined ( Fig. 3B ) and the transverse impression behind the eyes is smooth not punctate. Furthermore, in E. ovipennis , the apex of the aedeagus median lobe is either completely lacking or has only an obsolete tooth on its ventral side, which contrasts with the distinctive broad tooth found on E. dyschirioides . Eurylychnus ovipennis is sympatric with both E. regularis and E. cylindricus , but the much smaller body length of E. ovipennis (<10.4mm) allow it to be easily recognised from these species.

Redescription: Body shiny black, legs piceous or black, palps and antennae piceous. Body length 9.9–10.4mm; maximum pronotum width 3.1–3.2mm; maximum elytra width 3.6–3.8mm.

Head: Vertex covered in reticulation of very fine meshes. Transverse impression behind the eyes impunctate. Frontal impressions becoming obsolete posteriorly near the transverse impression behind the eyes, curving inwards anteriorly, joining with the frontoclypeal suture at the tentorial pits and continuing anteriorly down the clypeus, terminating in a seta before the anterior margins. Clypeus straight to weakly emarginated. Labrum moderately to strongly emarginated, with 6 evenly spaced setae on its dorsal anterior margins. Eyes with one supraorbital seta each. Mandibles with a seta in the scrobe. Mentum median tooth bifid, with a seta either side at the base; paramedian foveae present; lobes broad and squarish. Submentum with 2–6 setae. Stipes with 2 setae each, the inner seta being more than double the length of the outer. Gula convex with transverse wrinkles; gular sutures with small gular pits.

Thorax: Pronotum convex, especially laterally; covered in reticulation of very fine meshes; foveae present on the basal angles; base of pronotum with a broad, almost indistinct impression; margins constricted posteriorly from basal 1/3, with small tubercles on basal angles; pronotum widest at approximately the midline; lateral margins with 4 setae either side, the posterior most setae distant from the posterior angles while the anterior most setae are near to the anterior angles; median impression extending most of the length of the pronotum; pronotal carina borders the lateral margins, beginning at the anterior angles and terminating at the tubercles on the basal angles. Prosternum convex and smooth, anterior margin with a raised border. Protrochanters with 1 seta each, sometimes duplicated. Males with squamose setae on the ventral surface of protarsomeres 1–3. Metatrochanters with or without a seta. Mesocoxae and Metacoxae both with 2 setae.

Elytra: Elytral disc oval and convex; covered in reticulation of very fine meshes; lateral elytral carina borders elytra from humerus to apex. Parascutellar striole joined to apical portion of stria 1; elytra with 7 striae, with striae 1–4 distinct and 5–7 becoming obsolete; stria 5 begins on humeral angle; interstices flat and smooth; striae with weak irregular punctures. Basal groove with 3 asetose obsolete punctures on either side of the suture. Humeral angle converging downwards posteriorly where it meets the elytra carina.

Abdomen: Ventrites 3–5 with or without setae. Apical margin of ventrite 6 with a pair of paramedian setae.

Male genitalia: Aedeagus left paramere ( Fig. 5D ) broad, asetose, with a rounded dorsal edge and straight ventral margin; right paramere ( Fig. 5E ) long, thin, curving upwards gently, constricted in apical half. Short setae present along the ventral margin in the apical half, extending onto the dorsal margins and the middle of the paramere at the apex. Median lobe ( Fig. 5F ) moderately to strongly curved ventrally, deflected to the right; apex with a distinctive broad rounded projection, sometimes with an obsolete tooth ventrally.

Remarks: Eurylychnus ovipennis closely resembles E. dyschirioides , which Sloane noted in his description of E. ovipennis based on a single specimen. The following characters were given to separate E. ovipennis from E. dyschirioides : ‘form shorter; transverse impression of head weaker and impunctate; prothorax similar in shape, juxtabasal protuberance of border less prominent, four (not three) marginal setae on each side; elytra shorter, striae obsolescent, lateral channel narrower; femora piceous (not red)’ ( Sloane 1915: 445). In this study, a small series of E. ovipennis have been examined, including material from Barrington Tops (300 km south of the type locality of Dorrigo), and many of the characters listed by Sloane have been found to be variable or difficult to quantify. For example, the number of setae on the margin of the pronotum of E. dyschirioides is variable, and, given the variability in the number of setae in E. ovipennis on the submentum and ventrites 3–5, it is unlikely to be a reliable character for separating the two species. Other characters such as the strength of the elytral striae, colour of the legs and overall body form are useful for separating E. ovipennis from New England National Park and Dorrigo from E. dyschirioides , but the differences are less pronounced in specimens from Barrington Tops. The male genitalia, although not discussed by Sloane, appears to be distinctive in E. ovipennis , with the apex of the aedeagus median lobe with a broad round projection, contrasting with the often narrow and angular projection of the aedeagus median lobe apex of E. dyschirioides . In this character, the males collected from Barrington Tops closely resemble individuals from New England and Dorrigo, being only slightly less rounded and having an obsolete tooth ventrally. The tooth on the ventral side of the apex in E. dyschirioides is much broader and more pronounced than those on E. ovipennis from Barrington Tops. The present study highlights the tenuous nature of some of the characters used to distinguish E. ovipennis from E. dyschirioides , but is limited by the amount of E. ovipennis material available for study. Further work with a larger series of E. ovipennis from its southern and northern populations, as well as the inclusion of DNA analysis may help to resolve the status of this species.

Figures

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.