Euxanthellus Silvestri, 2025

Kresslein, Robert L., Polaszek, Andrew, Burks, Roger A., Mottern, Jason L., Lahey, Zachary & Heraty, John M., 2025, Nomenclatural spring cleaning: tidying Aphelinidae of taxa that do not spark joy, and a new species of Prococcobius Hayat (Aphelinidae: Coccophaginae), Journal of Natural History 59 (9 - 12), pp. 609-653 : 619-621

Euxanthellus Silvestri stat. rev.

( Figure 4 )

Euxanthellus Silvestri, 1915: 320 [in Silvestri 1915a]. Type species: Euxanthellus philippiae Silvestri, 1915 by original monotypy in Silvestri 1915a [examined].

Diagnosis

Female. Antenna 9-segmented; funicle 4-segmented with Fu1 subquadrate, closely associated with Fu2 ( Figure 4B ). Mesosoma with axilla (ax) with 5–11 setae; mesoscutellum with scutellar sensilla separated by 1–2× their diameter; metanotum with dorsellum (dor) diamond shaped ( Figure 4C ). Mesofurcal-mesopostnotal complex (f2b) with mesofurcal bridge complete and mesofurca shaped like ram’s horns ( Figure 4C ). Fore wing with stigmal vein constricted, extending into wing disc; postmarginal vein present, as long as stigmal vein ( Figure 4D ).

Male. Antenna as in species of the Coccophagus malthusi species group ( Hayat 1998, figs 309, 314, 317). Axilla with 3–5 setae. Otherwise as in female.

Material examined

Holotype: ERITREA: Nefasit. ex. Philippia chrysophyllae Silvestri, 1915 [= Stotzia chrysophyllae (Silvestri, 1915) ] [1♀, UNP]. Non-type material: SOUTH AFRICA: Claremont, 4. xi.1919, Rust, E.W., No. H, ex. Saissetia oleae (Oliver) on Sparmannia Buc’hoz. [= Rehmannia Libosch. ex Fisch. and C.A. Mey ] [1♂, UCRC: UCRCENT13050]; Capetown, 17.xi.1919, Rust, E.W., ex. Saissetia oleae (Oliver) on oleander [1♀, UCRC: UCRCENT13023]; Cape town, 4. vi.1924, Rust, E.W., No. 43 [1♀, UCRC: UCRCENT13031]; Rosebank, 9.iii.1925, Rust, E.W., ex. Saissetia hemisphaerica [= Saissetia coffeae (Walker) ] [1♂, UCRC: UCRCENT13017]; Camp’s Bay, 16.vii.1925, Rust, E.W., ex. Saissetia perseae Brian [= Parasaissetia nigra (Nietner) ] [1♂, UCRC: UCRCENT14196]; Pretoria, iv.1954, Bedford, E.C.G., ACDL 414, ex. Ceroplastes helichrysi var. sinoiae Hall [= Ceroplaster sinoiae Hall ] on Jacaranda Juss [6♀, UCRC: UCRCENT412694, UCRCENT498424]l West Cape, Wellington, 18.v.1959, Whitehead, V.B., S&R 1898–3, ex. Saissetia oleae (Oliver) on apricot [3♂, UCRC: UCRCENT19832, UCRCENT19834, UCRCENT19835]; West Cape, Wellington, 29.v.1959, Whitehead, V.B., S&R 1900, ex. Saissetia oleae (Oliver) on apricot [2♀, UCRC: UCRCENT19870, UCRCENT19871].

Comments

Euxanthellus stat. rev. was described for species that resemble Coccophagus but possess a 9-segmented antenna ( Figure 4B ) ( Silvestri 1915a). The genus was synonymised with Coccophagus by Hayat (1994) due to insufficient diagnostic characteristics to distinguish the genera. Heraty et al. (1997) explored the morphology of the mesofurcal-mesopostnotal complex in Aphelinidae and recognised that, in contrast to all other Coccophagus , species historically placed in Euxanthellus possessed a complete mesofurcal bridge and a ‘rams-horn shaped mesofurca’ (p. 62) ( Figure 4C ). The authors proposed that Euxanthellus should be treated as its own tribe and as the sister clade to Coccophagini + Pteroptricini . Hayat (1998) agreed that Euxanthellus should be treated as a valid genus in its own tribe.

While Euxanthellini and Euxanthellus have been recognised twice as valid, the taxa have not been formally treated. As a result, the species of Euxanthellus have frequently been called by the incorrect name in publications and public databases for the last quarter century ( Kondo 2006; Vikberg and Koponen 2008; Lotfalizadeh 2014; Rakimov et al. 2015; Phuong 2018; Noyes 2019). In conjunction with previous studies and contemporary phylogenomic analyses ( Kresslein 2024), we formally recognise Euxanthellus with four species therein ( Euxanthellus philippiae Silvestri, 1915 stat. rev., Euxanthellus subochraceus (Howard), 1907 stat. rev., Euxanthellus adustus Annecke and Prinsloo, 1976 stat. rev. and Euxanthellus desantisi Fidaglo, 1981 stat. rev.), and formally establish the tribe Euxanthellini .

The general habitus of Euxanthellus is superficially similar to species of the Coccophagus malthusi species group (Hayat 1993) and it keys to members of the malthusi group in several keys to species of Coccophagus (Hayat 1993, 1998; Xu and Huang 2004; Myartseva 2006). Additionally, Compere (1931) excluded species of Euxanthellus from his key to Afrotropical Coccophagus . Euxanthellus can be easily distinguished with the diagnostic charateristics presented above. Euxanthellus desantisi is readily diagnosable from the remaining species in Euxanthellus by the head shape, mesoscutellar setation, relative proportions of Fu1, and absence of the diamond-shaped dorsellum ( Fidalgo 1981, figs 1–4). Additionally, Euxanthellus desantisi is the only known species of Euxanthellus known from outside the Afrotropics. We have tentatively placed Euxanthellus desantisi with the remaining Euxanthellus to aid with diagnosis, but ultimately molecular data will be necessary to determine the appropriate placement of this species.

Figures

Figure 4. Euxanthellus Silvestri (Euxanthellini Heraty, Kresslein and Polaszek) female. (A) Habitus (lateral) female, (B) antenna (lateral) female, (C) mesosoma (dorsal); inset: mesofurcal-mesopostnotal complex, (D) Fore wing, inset: stigmal vein. dor: dorsellum; F1: first flagellar segment; F2: second flagellar segment; f2b: mesofurcal bridge.