Stenaleyrodes vinsoni Takahashi

Martin, Jon H & Streito, Jean-Claude, 2003, A second species of the enigmatic whitefly genus Stenaleyrodes Takahashi (Sternorrhyncha, Aleyrodidae), Zootaxa 349, pp. 1-15 : 3-4

Stenaleyrodes vinsoni Takahashi

Stenaleyrodes vinsoni Takahashi, 1938: 269 ­271. Syntypes, Réunion (MNHN, TARI).

“ Aleurodicus destructor Mackie”, Risbec, 1942: 58 –61. New Caledonia [misidentification]. Dialeurodicus elongatus Dumbleton, 1956: 129 –131. New Caledonia (Holotype MNHN; 1 paratype BMNH). [Synonymised by Mound & Halsey, 1978: 249 –250.]

Takahashi (1938) described S. vinsoni from Réunion, in the Indian Ocean. He did not state which subfamily he considered S. vinsoni to belong to, but declared it to be “related to Trialeurodes ” and also that it “resembles Bemisia ”, implying that he considered it to be a member of the subfamily Aleyrodinae.

Dumbleton (1956) described the same species from New Caledonia, on the other side of the world, under the name Dialeurodicus elongatus . However, the puparia are sufficiently distinctive for the synonymy of D. elongatus with S. vinsoni to be considered safe, and Takahashi’s decision to erect a new genus is also considered sound. However, the question of subfamily placement is less straightforward.

Dumbleton placed D. elongatus in the Udamoselinae, a subfamily established by Enderlein (1909) to accommodate a single new genus and species, Udamoselis pigmentaria , that was described from a solitary adult male. Moreover, he also included in this subfamily the genus Aleurodicus Douglas. Previously, Quaintance & Baker (1913) had erected a new subfamily, Aleurodicinae, to accommodate Aleurodicus , along with Dialeurodicus Cockerell and two other genera, and considered Udamoselinae with its single species to be distinct. Solomon (1935) discussed the characters used to distinguish these two subfamilies, and concluded that “the retention of a separate subfamily for Udamoselis is unjustified and it should be included in the subfamily Aleurodicinae”, despite this name not having nomenclatural priority. Sampson (1943) “with the greatest reluctance” accepted Udamoselinae rather than Aleurodicinae, without explicitly stating his reason, but presumably recognising that Udamoselinae was the older name, and Russell (2000) similarly did not comment on this situation in her review of whitefly subfamily names. In contrast, Mound & Halsey (1978) stated that U. pigmentaria should be regarded as nomen dubium [inadequate description, combined with loss of the sole specimen], thus revalidating Aleurodicinae as the second of only two subfamilies of Aleyrodidae .

Having decided (correctly, in our opinion) that elongatus was not a member of the Aleyrodinae, Dumbleton placed the species in Dialeurodicus on account of the absence of compound or agglomerate pores, and would have followed Sampson’s (1943) system when using the subfamily name Udamoselinae, rather than Aleurodicinae. In Stenaleyrodes , the complete absence of a claw at the apex of each puparial leg, and the lingula having only one pair of obvious setae, are characters that do mitigate towards inclusion in the Aleyrodinae. However, very close examination of the puparial lingula, in both species, does reveal a tiny second pair of setae ( Fig. 3 A), and this complement of 4 lingular setae is normally diagnostic for the Aleurodicinae. The puparial antennae are very long, corrugatesided in the apical half, describing an arc from anterior to the fore legs to at least the centre of the middle legs ( Fig. 5 A) — again an aleurodicine characterisic. Also, the elongate distal segment of each puparial leg ( Fig. 10 C) is more characteristic of the Aleurodicinae than of the Aleyrodinae, despite the absence of an apical claw. [The absence of puparial leg claws is a character also seen in some other Palaeotropical Aleurodicinae, but has only been seen in one known Neotropical member of the subfamily so far]. The very large puparial lingula ( Figs 3 A, 7), and the typical dorsal disc chaetotaxy again support the view that the Aleurodicinae is almost certainly the correct subfamily placement for Stenaleyrodes . Lastly, the absence of compound (wax filament­secreting) pores does not indicate exclusion from the Aleurodicinae, even though most included species do possess them, as Dumbleton clearly recognised. Even so, the puparia of S. vinsoni do secrete fine, faintly bluish­hued waxy filaments (“abundant long wax filaments .... similar to those of [ Aleurodicus ] destructor ” ­ Dumbleton, 1956), a character with which Dumbleton strengthened his case for placement in this subfamily. Dumbleton explicitly mentioned the wax filaments in comparison with those of Aleurodicus destructor for a good reason ­ he had realised that Risbec (1942) had taken over two pages of text and nine illustrations to describe “ Aleurodicus destructor ”, when Risbec actually had D. elongatus (i.e. S. vinsoni ) in front of him.

The discovery of adults of S. papillote has further reinforced the case for retaining Stenaleyrodes in the Aleurodicinae. The lingula can be seen to possess 4 setae more clearly than in the puparia ( Fig. 10 B) and the presence of an acute, seta­like, paronychium between the tarsal claws ( Fig. 5 B) is also an aleurodicine character.

Figures

FIGURE 3 (A­B). S. papillote, puparium. A, vasiform orifice, with four lingular setae discernible; B detail of operculum.

FIGURE 5 (A – B). S. papillote. A, puparium, thorax and anterior abdomen; B, adult female, tarsus with acute paronychium.

FIGURE 10 (A – C). S. papillote. A, female, cephalic process between antennal base and eye; B, female, lateral view of lingula, with three of its four setae clearly visible in relief; C, puparium, leg.