Bemisia euphorbiarum Hernández-Suárez and Malumphy, 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 : 20-22

Bemisia euphorbiarum Hernández-Suárez and Malumphy sp. nov.

( Figures 15, 31, 52–55, 76–77)

PUPARIUM ( Figs 15, 54, 55). Habitus. Most frequently observed feeding on the lower surfaces of the foliage but puparia are also common on the upper leaf surfaces and occasionally on the stems. Usually with a thick dorsal layer of wax when developing on the upper surfaces, lending a greyish appearance. Cuticle is generally pale, but uppersurface individuals often have distinctly brownish pigmentation. Margin. Outline oval to elongate-oval, 1.25 mm long, 0.84 mm wide [n=11], generally widest at abdominal segment I. Margin finely crenulate, about 12 shallow teeth per 0.1mm with thoracic tracheal areas not differentiated. Dorsum. Longitudinal moulting suture reaching puparial margin; transverse moulting sutures nearly reaching submarginal area. Submedian area of dorsal disc smoother than submargin but may be defined by a line of tubercules which are much more obvious in upper surface specimens ( Fig. 15, left); abdominal segmentation and meso-metathoracic division well marked and abdominal segment VII significantly reduced in length medially such that only seven segments are discernible along median line; submedian abdominal depressions little marked. Vasiform orifice acuminate-triangular, inset from puparial margin by its own length, and leading into a very narrow caudal furrow bounded by caudal ridges that are well defined; operculum cordate, occupying less than half length of vasiform orifice, finely setose; lingula head exposed, slender elongate, apically acute, a stout setae on each side of apical point, but lingula entirely accommodated within vasiform orifice; vasiform orifice floor with inner ridges ( Fig. 15). Chaetotaxy. Anterior and posterior marginal setae present, hair-like, only slightly shorter than caudal setae. Normal dorsal disc chaetotaxy comprises single submedian pairs of cephalic, eighth abdominal and first abdominal setae, all minute; eighth abdominal setae placed lateral to anterior edge of vasiform orifice; a pair of marginally-placed caudal setae present, which are the longest of all the setae, plus a row of twelve minute submarginal setae on each side. Pores. Simple pores of the geminate pore/porette type present; four rows of simple pores in submarginal and submedian areas; two pairs of the geminate pore/porette type on each side of abdominal segments, including two pairs on each side of abdominal segment I between first abdominal setae ( Fig. 31). 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 two tiny basal setae, the antennae usually overlain by fore legs. Antennal bases anteromesad to fore legs. Tracheal folds lightly stippled.

OVUM ( Fig. 52). Habitus. Elliptical, broadly rounded at the base and narrow apically. Cream coloured when first laid, becoming dark brown to almost black. Red eyes and yellow mycetome bodies of the first instar just visible prior to hatching. Eggs are scattered, laid singularly or in small groups, usually on the lower surface but also fre- quent on the upper surface of the foliage, and less frequently on the stems. The chorion is smooth and shiny with little wax evident. Each egg is erect and firmly attached to the leaf surface by a slender, short peduncle extending from the base of the egg, inserted into the plant tissue. After hatching, the egg remains upright and is a dark golden brown colour. Length 204 microns (200–208 microns), width 86 microns (78–96 microns), 2.39 (2.17–2.62) times longer than wide. Peduncle length 40 microns and width 12 microns.

FIRST-INSTAR LARVA. Ha bitus. Scale-like, pale translucent yellow, becoming dark grey as they mature. Reddish eye spots and two yellow abdominal mycetomes are just visible. A narrow band of white wax is present around the margin. Margin. Outline ovoid, lozenge-shaped; length 291 microns (276–310 microns) and width 192 microns (182–202 microns), 1.51 (1.42–1.57) times longer than wide. With 16 pairs of well-developed setae: Caudal setae (CS) length 63 microns (58–69 microns); Marginal setae (MS) 14 pair length 69 microns (64–76 microns); ratio CS/MS14 = 0.91 (0.83–1.01). Margin evenly, faintly crenulate. Dorsum. Some slide-mounted specimens are brown in colour. Chaetotaxy comprises paired anterior submarginal seta length 29 microns (26–31 microns); cephalic seta length 3 microns (3–4 microns); first abdominal seta length 3 microns (2–4 microns); eighth abdominal seta length 4 microns (3–5 microns). Cephalic tubercles usually weakly developed, oval. Vasiform orifice almost quadrate and closed behind, length 30 microns (28–32 microns). Lingula head spinulose with two pairs of stout setae, half-covered by the operculum. Operculum and lingula pigmented light brown. Venter. Legs well developed. Fore coxae with short spine, mid and hind coxae with long setae and short spines. Tibia-tarsi distinctly spinose. Antennae long and slender, length 81 microns (77–85 microns). Abdominal setae almost parallel to anterior margin of vasiform orifice or displaced slightly behind. Cuticle fine, diaphanous.

ADULT ( Figs 53, 76, 77). Habitus. Head and antennae grey; thorax grey with scutellum greyish-yellow; legs grey; abdomen yellowish with grey base, genitalia and dorsum with paired transverse grey bands; wings covered with sparse, grey powdery wax. The greyish appearance described above is due to waxy secretions, and the true body colour and sclerotic patterning are shown in Figs 76 & 77. Head and thorax, base of abdomen, areas of the tergites, male collar and female gonapophysis and supragenital plate, legs and antennae, all strongly pigmented brown; wings hyaline. Antennae 7-segmented. Antennal segment II about half as long as antennal segment III; antennal segment III about as long as segments IV–VII combined; segments V–VII subequal, segment IV much shorter. Segment II with long, slender, conical sensorium which may be difficult to distinguish from the enlarged setae. Segment III with one sensorium located on the proximal portion, and three sensoria (a cone and two rhinarialtypes) on the distal portion. The cone is approximately a quarter of the segment length away from the apex. Segment IV without a sensorium; segment V with a distal rhinarial-type sensorium; segment VI with a subapical sensorial cone, and segment VII with both a sensorial cone and an adjacent rhinarial sensorium, arising near the middle of the segment and the segment terminating in a narrow conical sensorium. Upper eye composed of 60–67 ommatidia, each 10 microns in diameter; lower compound eye composed of 41–42 ommatidia, each 12 microns in diameter, arranged in interconnected groups of 6 pigmented ommatidia surrounding a clear, smaller ommatidium. Upper and lower eyes separated by a space equal to or slightly less than the width of an ommatidium. Metatibial combs consisting of 21–24 setae, mesotibial brushes consisting of 3–4 adjacent setae. Male claspers paired, with about 10 long setae. Aedeagus ventral base smooth; distal portion curved upwards, tapering and pointed. Female cement gland is sinuous, without bands and with a small head.

Etymology: This whitefly species colonises several different Euphorbia species , belonging to the subsection. Pachycladae, comprising E. regis-jubae , E. lambii , E. lamarckii , E. balsamifera and E. atropurpurea ; thus B. euphorbiarum is considered an appropriate name.

Material examined: Holotype puparium—GRAN CANARIA, Las Palmas de Gran Canaria, Zárate, 04.i.2001 (C. Malumphy coll. CM2001–4) on Euphorbia balsamifera or E. regis-jubae (BMNH) . Paratypes: 25 puparia, 6 third instars, 7 first instars, 10 adults, same data as holotype ( FERA); 2 puparia, same data as holotype but (#CM92-010) on E. balsamifera , 31.iii.1992, with Acaudaleyrodes rachipora (FERA) ; 10 puparia, 4 eggs, same data as holotype but ( CM 11-393) on E. regis-jubae , 8.i.2011, duplicate material stored in ethanol ( FERA); 8 puparia, 1 adult and 9 second and third-instars nymphs, TENERIFE, Barranco near Punta del Hidalgo, 28.xi.2000 (Martin #7495) on E. lamarckii var. wildpretii ; 9 puparia TENERIFE, Barranco de las Moradas, near Icod de los Vinos [approx. 300– 500m] 18.v.1997 (Martin #7051) on E. lamarckii var. wildpretii ; 6puparia and 1 first-instar nymph TENERIFE, Bajamar, 26.xi.2000 (Martin #7492) on E. lamarckii var. wildpretii ; 17 puparia TENERIFE, Valle de Guerra [Govt.Agric.Labs] 20.v.1997 (Martin #7057) on E. lambii (BMNH, TFMC-ENTOMO, MNCN, USNM) . Other material examined: LANZAROTE: Playa Blanca, 30.xii.1997 (E. Hdez.) on E. regis-jubae , same data but: 29.xii.1996 on E. balsamifera ; Costa Teguise, 9.iii.1997 (E. Hdez.) on E. balsamifera , same data but 8.iii.1997 (E. Hdez.) on E. balsamifera ; GRAN CANARIA: Moya, 22.i.1998 (E. Hdez.) on E. regis-jubae , E. balsamifera ; Barranco Azuaje, 22.i.1998 (E. Hdez.) on E. regis-jubae . TENERIFE: Valle Guerra, 12.vi.97 (E. Hdez.) on E. atropurpurea , same data but 22.v.1997 on E. atropurpurea , 20.v.1997 on E. lamarckii var. wildpretii ; Erjos, 6.iv.1997 (E. Hdez.) on E. lamarckii var. wildpretii ; Cuevas Negras, 29.vi.1997 (E. Hdez.) on E. lamarckii var. wildpretii ; Barranco del Agua, 11.i.98 (E. Hdez.) on E. lamarckii var. wildpretii ; Barranco de las Moradas, 6.iv.1997 (E. Hdez.) on E. lamarckii var. wildpretii , same data but 18.v.1997 (E. Hdez.) on E. lamarckii var. wildpretii ; LA GOMERA: San Sebastián, 14.vi.1997 (E. Hdez.) on E. berthelotii ; Hermigua, 15.vi.1997 (E. Hdez.) on E. lamarckii var. wildpretii ; Barranco Santiago, 24.i.1998 (E. Hdez.) on E. lamarckii var. wildpretii ; LA PALMA: Puerto Nao, 22.vi.1997 (E. Hdez.) on E. balsamifera ; Los Sauces, 21.vi.1997 (E. Hdez.) on E. lamarckii var. wildpretii ; Los Cancajos, 21.vi.1997 (E. Hdez.) on E. lamarckii var. wildpretii ; Road Tazacorte, 22.vi.1997 (E. Hdez.) on E. lamarckii var. wildpretii ; Barranco de las Angustias, 22.vi.1997 (E. Hdez.) on E. lamarckii var. wildpretii .

Material was also observed in the field in LA GOMERA (road San Sebastián) and EL HIERRO (Sabinosa) but vouchers were not collected.

Comments: The puparia of B. euphorbiarum are morphologically similar to B. afer sens . lat. but may be distinguished using the following suite of characters: cuticle generally pale, or with diffuse brownish pigmentation, but without a regular pigmented pattern; dorsal submedian abdominal depressions indistinct and all dorsal setae minute; dorsum with a row of normally 12 minute setae on each side, located in the submarginal area, and without lobulate protuberances. In life, puparia are covered with a thick dorsal layer of translucent wax. The adults of B. euphorbiarum are distinctive and easily distinguished from those of B. afer sens . lat. The head and thorax of B. euphorbiarum are pigmented dark brown (appearing grey in life due to a coating of wax), whereas the head and thorax of B. afer sens . lat. are unpigmented. Bemisia euphorbiarum is the only Bemisia species that feeds on Euphorbia subsection Pachycladae.

Although not considered a major pest in the Canary Islands this whitefly can achieve high populations that produce leaf distortion, curling chlorosis and premature leaf-drop of ornamental Euphorbia shrubs. Most puparia cause a chlorotoic spot on the leaf surface opposite the feeding surface. B. euphorbiarum may occur on the same leaves as puparia of Acaudaleyrodes rachipora . The occurrence of puparia of B. euphorbiarum on both surfaces of leaves is unusual but certainly not unique: for example, puparia of B. afer complex on Laurus nobilis in England occasionally develop on the upper surfaces of leaves (C. Malumphy, personal observations).

The holotype has been selected because this particular puparium still contains the head and thorax of the pharate adult and clearly displays separated upper and lower eyes. However, adults collected on Euphorbia , that appear to be B. euphorbiarum , also exhibit upper and lower eyes conjoined by one ommatidium, a situation also noted by Malumphy et al. (2009). Molecular research aligns B. euphorbiarum populations with New World Bemisia afer complex ( Gill & Brown, 2010).

Euphorbia regis-jubae , apparently the preferred host for B. euphorbiarum , is distributed in the eastern Canary Islands (Lanzarote, Fuerteventura and Gran Canaria) and in south-western Morocco, on cliffs, rocky slopes and disturbed areas. E. lamarckii is a western Canarian endemic species; two varieties ( var. lamarckii in the south an west, and var. wildpretii in the north) occur in Tenerife, and only one variety ( var. wildpretii ) occurs in La Gomera, La Palma and El Hierro. E. atropurpurea is endemic to the south and west of Tenerife Island where it is exposed to humid winds on cliffs, whilst E. berthelotii is endemic to the south and west of La Gomera. E. balsamifera Ait. is present on all of the Canary Islands, mainly in the lower-altitude regions near the coast, but also grows in North Africa.