Oliarus Stål sensu Emeljanov, 1862

Löcker, Birgit, Fletcher, Murray J., Larivière, Marie-Claude & Gurr, Geoff M., 2006, The Australian Pentastirini (Hemiptera: Fulgoromorpha: Cixiidae), Zootaxa 1290 (1290), pp. 1-138 : 20-21

Genus Oliarus Stål sensu Emeljanov

Oliarus Stål, 1862: 306 .

Type species Cixius walkeri Stål, 1859 .

Morphology

Body length: ♂ 3.7–9.1 mm, ♀ 4.1–7.4 mm.

Head: Vertex (total length) 1.7–3.9 times longer than wide; lateral carinae strongly elevated; subapical carina forking from lateral margin at around 1/4–1/2 of total length of vertex; median carina 1/4–2/3 as long as median length of vertex. Position of maximum width of frons more or less around centre of frontoclypeal suture; lateral carinae of frons convex (rectilinear apically) or s­shaped. Anteclypeus with well­developed median carina.

Thorax: Forewing with fork ScRA+RP distad or basad of fork CuA1+CuA2; r­m crossvein distad or basad of fork MA+MP; RP apically bifid (rarely trifid); MA apically bifid, trifid or tetrafid; MP apically bifid; fork of Pcu+A1 distinctly basad or more or less around centre of clavus. Hind leg: tibia with 2 lateral spines; 6 (rarely 7) large apical teeth; 1 st tarsomere with 7–8 (rarely 9) apical teeth and no platellae; 2 nd tarsomere with 5 (rarely 6) apical teeth and no platellae.

Male genitalia: Genital styles with or without medium sized, sclerotised, spinelike, dorsal process.

Distribution

Australia (Queensland, Northern Territory, Western Australia), Christmas Island, Indonesia, Papua New Guinea.

Remarks

Females (unless associated with males, see comments in Material & Methods section) could only be identified to generic level. The body length measurement given above is derived from females assigned to species level plus additional females which could only be identified to genus.

The fork of ScRA+RP in the forewing is distad of the fork CuA1+CuA 2 in all species of the genus except for O. busoensis , where it lies basad. In the acanthopygophoris group the r­m crossvein is basad of the fork MA+MP, whereas in all other Oliarus it is distad. Typically in this genus RP is bifid apically; however, in some specimens of O. busoensis a trifid RP was recorded. In O. acanthopygophoris and O. lawlerorum the nodus of the yvein is more or less around the centre of the clavus, whereas in all other species of the genus it is shifted distinctly basad of the centre. The chaetotaxy of the hind legs in specimens of O. kampaspe varied from the typical chaetotaxy in this genus which is 6 large apical teeth on the tibia, 7 apical teeth on the 1 st tarsomere, and 5 on the 2 nd tarsomere. Most specimens of O. kampaspe had 7 large apical teeth on the tibia; all specimens had 8 apical teeth on the 1 st tarsomere; and in some specimens we found 6 apical teeth on the 2 nd tarsomere. Species of the acanthopygophoris group are unique within this genus in having a medium­sized, sclerotised, dorsal process.

As Hoch (2005) noted, “ Oliarus Stål, 1862 has long been a notorious catch­all genus for Pentastirine Cixiidae from nearly all parts of the world.” In recent years several attempts have been made to divide the complex Oliarus s.l. into more natural genera. Several new genera were created by authors such as Emeljanov (1992, 2001a), Mead & Kramer (1982) and Van Stalle (1985, 1986a, 1986b, 1986c, 1986d, 1987, 1991) to accommodate Palaearctic, Ethiopian, and Nearctic species previously described in Oliarus . Emeljanov also proposed a new concept for Oliarus s. str. ( Emeljanov 2001b), “Typical members of Oliarus s. str. are characterised by the more or less narrow macrocoryphe (‘vertex’); acuteangularly projecting forward anterior carina of the coryphe touching medially the anterior carina of the macrocoryphe (i.e. the acrometope subdivided into a pair of longitudinal triangles); elongate styles with thick medioventral heel tapering to the apical hook­like dilation; apical dilation usually with acute anterolateral angle and sometimes with blunt projections of posteromedial and posterolateral angle.” Consequently, only 46 species from the Oriental and Australian region remained in Oliarus sensu Emeljanov. Our investigations of the Australian fauna revealed a distinct group, sharing the features of Emeljanov’s concept of Oliarus s. str. They are further characterised by the presence of 5 spines on the second hind tarsomeres and only 2 lateral spines on the hind tibia (this feature separates them from all other Australian Pentastirini , which have 3–4 lateral spines). Hoch (2005) recently clarified the identity of the type series of O. walkeri Stål , the type species of Oliarus . She emphasised that the aedeagus of O. walkeri shows certain highly apomorphic characters, such as lack of articulation between phallotheca and flagellum and flagellum sheathed by processes of phallotheca which do not seem to be present in any other species of Oliarus sensu Emeljanov. In the Australian species, the flagellum shows various forms ranging from very small, hardly detectable and not articulated in O. acanthopygophoris , to large and more clearly articulated (e.g., in the gracilis group). Based on our investigations of the Australian Pentastirini fauna, we found that especially in the structure of the aedeagus there is an enormous amount of diversity. For this reason, we have retained these Australian species within the genus Oliarus . Comprehensive phylogenetic analyses of the Pentastirini fauna are needed to clarify whether there are more genera lurking within Oliarus sensu Emeljanov.