Siphoninus finitimus Silvestri, 2012

Hernández-Suárez, Estrella, Martin, Jon H., Gill, Raymond J., Bedford, Ian D., Malumphy, Christopher P., Betancort, J. Alfredo Reyes & Carnero, Aurelio, 2012, 3212, Zootaxa 3212, pp. 1-76 : 27-29

Siphoninus finitimus Silvestri stat. rev.

( Figures 34 & 84)

Siphoninus finitimus Silvestri, 1915: 247–249 .

Siphoninus phillyreae multitubulatus Goux, 1949: 11 . Revised synonymy.

PUPARIUM ( Fig. 34). Habitus. The immature stages occur in aggregations on the undersides of leaves of their host plants, usually covered by a fine white waxy secretion. Cuticle is pale with two discret dark spots around vasiform orifice and in cephalothorax ( Fig. 84). Margin. Outline oval, 0.99mm long, 0.67mm wide [n=6], generally widest at abdominal segment I (n=6). Margin undulate with thoracic tracheal combs present. Dorsum. Longitudinal moulting suture reaching puparial margin; transverse moulting sutures reaching submarginal area. Submargin smooth. Submedian/subdorsal area of dorsal disc smooth; abdominal segmentation and meso-metathoracic division well marked and abdominal segment VII not significantly reduced in length medially; submedian abdominal depressions not marked. Vasiform orifice rounded-cordate, its floor with multiple cells which vary in number, the orifice inset from puparial margin by approximately its own length; operculum laterally-rounded trapezoidal, occupying less then half of vasiform orifice, its posterior margin finely setose; lingula head rounded, only slightly expanded, exposed. Caudal furrow not defined. Chaetotaxy. Anterior and posterior marginal setae present, hairlike, only slightly shorter than submarginal setae. Normal dorsal disc chaetotaxy comprises single submedian pairs of cephalic, eighth abdominal and first abdominal setae all hair-like and of similar length; eighth abdominal setae placed anterior to vasiform orifice; a pair of submarginally-placed caudal setae present plus a row of fourteen submarginal setae in each side. All submarginal setae hair-like. A row of 25–26 siphons, placed in submarginal-subdorsal area on each side of body; three pairs of siphons in cephalothorax and a variable number of siphons (from 6 to 9) of similar size in abdominal segments. Pores. Simple pores present; the simple pores not evidently of the geminate pore/porette type. Venter. Cuticle smooth, diaphanous. Ventral abdominal setae underlying vasiform orifice. Legs bisegmental and with apical adhesion pads directed anteriorly on the fore legs, and posteriorly on the middle and hind legs. Middle and hind legs each with a tiny basal setae. Antennal bases anterolateral to fore legs. Tracheal folds unpunctuated.

Distribution in the Canary Islands: TENERIFE: Las Mercedes. LA GOMERA: Chipude, Barranco Santiago. Elsewhere: Palaearctic Region: Corsica, Jordan, Spain; Ethiopian Region: Eritrea, Ethiopia; Neotropical Region: Chile, Peru.

Host plants in Canary Island: Picconia excelsa . Other host plants listed: Olea europaea (Corsica, quoted host of S. phillyreae multitubulatus and host of BMNH sample), Olea chrysophylla (Eritrea, quoted host of S. finitimus ), “olive”, Olea sp. (Chile, Peru), Olea africana (Ethiopia) .

Comments: There has been controversy concerning the significance of variation in the number, length and distribution of dorsal glandular siphons on puparia of Siphoninus species. Material collected in Europe on a particular host, but in different seasons, shows no significant variation. Also, there seems not to be a simple correlation between the host plant and siphon length. However, the number, distribution and length of puparial siphons does, now, appear to be of significance in delimiting some species ( Table 1), and has led us here to reinstate S. finitimus as a valid species, with S. phillyreae multitubulatus becoming a synonym of S. finitimus rather than of S. phillyreae .

Material of S. phillyreae from rosaceous hosts in Spain, Italy, France and England has been examined, including material from Cotoneaster , Crataegus , and Pyrus ( Table 1), along with material from Fraxinus . There is variation in siphon number but an average of 50 siphons (46–52) are always present in the submarginal area, with 2 submedian pairs in the cephalothorax and from 6 to 10 submedian siphons on abdominal segments. The mean length of submarginal siphons in S. phillyreae is 0.08mm (0.06mm to 0.09mm, N=38). The mean size of puparia is 0.87mm long and 0.63mm width.

Silvestri described S. finitimus from Olea chrysophylla in Eritrea, based on the number and length of its siphons, with a total of 75–79 dorsal siphons with an average length of 0.084 –0.098 mm. There is also material from Ethiopia in BMNH, identified as S. finitimus (three slides with following data: Ethiopia, Sebeta, ex Olea africana , 27.xi.1975, D.J.Greathead, sample nº 38b CIE A8481): the mean submarginal siphon length is 0.15mm, with 53–81 submarginal siphons present, plus 2 cephalothoracic and (6–10) submedian abdominals. Goux (1949) discussed several subspecies based on the number and length of siphons. He described S. phillyreae multitubulatus from Olea europaea L. in Corsica, based on its larger size and more numerous and larger siphons in the submarginal area (mean number of 35 to 45). He mentioned that both S. finitimus Silvestri and S. inaequalis (Gautier) presented a variable number of submedian siphons in the abdominal segments but always have two pairs in cephalothoracic region. Mound & Halsey (1978: 192) placed S. finitimus and S. phillyreae multitubulatus as junior synonyms of S. phillyreae (Haliday) , along with other taxa—see account of S. phillyreae below. We now consider S. finitimus to be a distinct species (stat. rev.), with S. phillyreae multitubulatus its junior synonym (revised synonymy).

Independently, similar observations to our own have been made recently by Valencia (2011) who has documented differences between puparia and adult whiteflies from populations on olive and pomegranate in Peru, as well as differences in parasitoid preference.

In the Azores, a completely different siphon-morphology has been observed on the puparia of populations on Picconia azorica , the same plant genus that hosts S. finitimus in the Canaries, indicating that siphon numbers and distribution are important diagnostic characters. We consider that the species found on Picconia in the Azores represents an undescribed species.