Ferrisia gilli Gullan

Kaydan, M. B. & Gullan, P. J., 2012, 3543, Zootaxa 3543, pp. 1-65 : 26-29

Ferrisia gilli Gullan

( Figs 2B, C, 10)

Ferrisia gilli Gullan , in Gullan et al., 2003: 728.

This species was described from Alabama, California, Georgia and Louisiana, U.S.A., from pistacio, other trees and grass ( Gullan et al. 2003). The adult female and all female nymphal instars were described and illustrated. In California, this species is commonly called Gill’s mealybug, as it was named to honour Raymond Gill. Infestations of F. gilli are a problem in orchards and vineyards in California ( Daane et al. 2008, 2012; Haviland et al. 2006, 2012) and slide-mounted specimens from some infestations are deposited in the BME and CSCA. In particular, there are recent CSCA records of F. gilli from vineyards in El Dorado, Fresno, Lake, Lincoln and Placer counties, California, as well as 2011 FSCA records from vineyards in Winchester, Virginia.

The status of F. gilli as a species distinct from F. quaintancii requires confirmation even though the adult females differ substantially in morphology. For example, the adult female of F. gilli is distinguished readily from that of F. quaintancii by the presence of more than 90 enlarged tubular ducts on the dorsum, compared with 0–2 ducts on F. quaintancii . However seven samples (six from California and one from Alabama) of F. gilli that were sequenced for the study of Gullan et al. (2010) formed a group with a single immature specimen of putative F. quaintancii (from the roots of Rhus copallina in Florida) in all data partitions and analyses. We continue to treat F. gilli and F. quaintancii as separate species pending further collection of specimens of F. quaintancii for use in DNA investigation. Refer to the discussion of this taxonomic problem and a more detailed comparison of F. gilli and F. quaintancii under the text for the latter species.

It seems clear that there is environmentally based variation in the number of small oral-collar tubular ducts per marginal cluster as well as the number of marginal clusters of these ducts on adult females of F. gilli ( Gullan et al. 2010) . This variation may be induced by temperature of development of the mealybug and/or by host-plant effects. For example, adult females of F. gilli collected from Laurus nobilis in Davis, California, during June 2003 had fewer small tubular ducts than females of the next generation collected from the same individual tree in August 2003, suggesting that temperature may affect expression of these ducts. Furthermore, specimens with many small tubular ducts (in segmental clusters around the entire body) that were collected from Magnolia in Davis, California, were almost identical genetically to other Californian specimens of F. gilli that had few small tubular ducts and were collected from host plants other than Magnolia ( Fig. 3; see Table 1 of Gullan et al. (2010) for collection data). Many adult female specimens from the eastern and southeastern United States that were collected from Magnolia and certain other tree species have clusters of small oral-collar tubular ducts segmentally around the body with numerous ducts per cluster (usually more ducts per cluster than on females from Magnolia in Davis). Gullan et al. (2003: 738) discussed specimens that had clusters of two to many oral-collar ducts marginally on most segments and with a cluster always near the base of each antenna, but they tentatively attributed these differences to an undescribed species that was closely related to F. gilli . Fresh material of this alternative phenotype was not available to Gullan et al. (2003) for DNA analysis, and thus they excluded those specimens from the description of F. gilli . Gullan et al. (2010) obtained DNA sequences from females of the alternative phenotype (from Magnolia grandiflora in Davis) and showed that these specimens (CA 6 and CA 7 in Fig. 3) were part of the F. gilli clade. Below we describe and illustrate this alternative phenotype, which we call the Magnolia form of the adult female of F. gilli ( Fig. 10).

Material examined ( Magnolia form): UNITED STATES OF AMERICA: 6 adult ♀ (6 slides), ex Magnolia grandiflora , Alabama, Dale Co., Ft. Rucker , 18.vii.1978, T.B. Hagler, Al-084-78, ( AUCC) ; 1 adult ♀, ex Cercis canadensis , Alabama, Lee Co., Chewacla State Park , 17.iv.1976, B.J. Muse, Al-720-76 ( AUCC) ; 1 adult ♀, ex funnel trap in tupelo swamp, Alabama, Baldwin Co., 1.5 mi. SW Stockton , 10.iv.1975, J.D. Harper et al., Al-078- 79 ( AUCC) ; 1 adult ♀, ex Cornus florida , Alabama, Randolph Co., Wedowee , 20.v.1977, M.L. Williams, Al-94-77 ( AUCC) ; 1 adult ♀, ex Carya tomentosa , Alabama, Randolph Co., 25.vii.1977, C.H. Ray Jr, I. Daniels & K. Manuel, Al-184-77 ( AUCC) ; 3 adult (3 slides), ex M. grandiflora , Alabama, Tuscaloosa Co., 9.v.1974, Pigott, AL- 30-74 ( AUCC) ; 11 adult ♀ (11 slides including DNA voucher FBK035), ex trunk of Laurus nobilis , California, Yolo Co., Davis, Downtown , on Third St near G Street , 3.vi.2003 and 1.viii.2003, T. Kondo ( BME) ; 7 adult ♀ (7 slides including DNA vouchers FBK046 & NH162), ex leaves and fruit of Magnolia grandiflora , California, Davis, corner of Russell Blvd and La Rue Road , 10.x.2006 by M.B. Kaydan, 11.ix.2008 by P.J. Gullan & A.R. Van Dam ( BME) ; 4 adult ♀ (2 slides) ex leaves of Zamia sp. ?, Florida, Coral Gables (U of M), 11.i.1966, S. Nakahara ( USNM) ; 1 adult ♀, ex Ceratiola ericoides , Florida, Port Saint Lucie , 21.xii.1983, K. Hibbard ( FSCA) ; 1 adult ♀, ex Magnolia , Georgia, Early Co., 23.vii.1969, H.H. Tippins, HHT-113-69 ( AUCC) ; 3 adult ♀ (1 slide) ex Magnolia sp. , Louisiana, New Orleans , 08.iv.1945, Rau coll. Sp. Surv. 25250 ( USNM) ; 1 adult ♀, ex Robinia pseudoacacia , Virginia, Blacksburg , VPI campus, 19.v.1969, R.C. Brachman, Va 770 ( USNM) ; 2 adult ♀ (1 slide), ex Liquidambar styraciflua , Virginia, Montgomery Co, Blacksburg, VPI campus, Plot 65 II F, 052269, 22.v.1969, D.K Puller ( USNM) ; 1 adult ♀, ex sycamore ( Platanus occidentalis ), Virginia, Charlottesville , 09.v.1946, D.W. Clancy ( USNM) ; 2 adult ♀ (1 slide), ex Magnolia , Virginia, Richmond , 15.viii.1963, M. Kosztarab and D.V., Va. 27E ( USNM) ; 7 adult ♀ (3 slides), ex Magnolia grandiflora , Virginia, Richmond , collected by M. Kosztarab as 2 nd & 3 rd instar nymphs, raised to adulthood on potatoes in lab. N.Y. ( USNM) .

ADULT FEMALE. Diagnosis (based on both Magnolia and type forms). Ferrisia gilli can be diagnosed by having the following combination of features: absence of anterior ostioles; ventral oral-collar tubular ducts of more than one size; clusters of small oral-collar tubular ducts on ventral margins of at least the posterior abdominal segments, sometimes on all body segments; ventral oral-collar tubular ducts generally associated with 1 or 2 minute discoidal pores around duct rim (never touching rim), each pore 2.5–3.5 µm in diameter; dorsal enlarged tubular ducts totalling 90–144 on dorsum, with 1 or 2 oval discoidal pores usually associated with rim of each duct opening; number of multilocular disc pores on venter of abdominal segments as follows: 5–20 on segment VII, and 6–23 on segment VIII + IX; anterior pair of ostioles absent, posterior pairs well developed.

The morphological form of F. gilli found on Magnolia and several other tree hosts is similar to the type form of F. gilli , but differs by having many more marginal clusters of oral-collar tubular ducts (clusters confined to posterior abdomen in type form) and a high number of small oral-collar tubular ducts in the marginal duct clusters of body segments excluding abdominal segment VIII (3–29, often more than 10, per cluster in the Magnolia form and 0–7, mostly 3–5, per cluster in the type form). All adult females of F. gilli lack anterior ostioles, as do adult females of F. claviseta , F. quaintancii and F. setosa , but in the first two of the latter three species, the dorsal enlarged tubular ducts usually number fewer than 12, whereas F. gilli usually has more than 100 enlarged ducts. Furthermore F. setosa has more than 2 cerarian setae on each cerarius and more than 6 anal ring setae, whereas F. gilli has 2 conical setae on each cerarius and 6 anal ring setae. The Magnolia form of F. gilli is similar to F. milleri by having small oral-collar tubular duct clusters on all body segments, but can be separated from F. milleri by the absence of anterior ostioles and absence of multilocular pores on abdominal segment VI (both features present in F. milleri ).

Description of slide-mounted specimens of Magnolia form (based on 30 females; Fig. 10) [See Gullan et al. (2003) for description of type form of F. gilli ]. Body elongate oval, 2.94–5.36 mm long, 1.22–2.44 mm wide. Eye marginal, 55–85 µm wide. Antenna 8 segmented, 550–780 µm long; apical segment 122–148 µm long, 30–45 µm wide. Clypeolabral shield 190–250 µm long, 110–145 µm wide. Labium 210–250 µm long, 170–250 µm wide. Anterior spiracles 70–115 µm long, 40–68 µm wide across atrium; posterior spiracles 82–120 µm long, 55–80 µm wide across atrium. Circulus quadrate, 125–245 µm wide, divided by an intersegmental line. Legs well developed; hind trochanter + femur 425–560 µm long, hind tibia + tarsus 435–580 m long, hind claw 35–45 µm long. Ratio of lengths of hind tibia + tarsus to hind trochanter + femur 0.96–1.05, ratio of lengths of hind tibia to tarsus 2.37–2.82, ratio of length of hind trochanter + femur to greatest width of femur 3.88–4.45. Tarsal digitules subequal, each 62–70 µm long. Claw digitules subequal, each 40–45 µm long. Translucent pores present on hind legs, totalling 37–110 on coxa, femur and tibia combined. Ostioles: only posterior pair present; each ostiole with 41–56 trilocular pores and 8–10 setae. Anal ring 125–160 µm wide, with 6 anal ring setae, each seta 220–265 µm long.

Dorsum. Anal lobe cerarii each with 2 conical setae, each seta 35–45 µm long, with 31–44 trilocular pores and 4–6 bluntly-tipped auxiliary setae. Dorsal body setae slender, each 15–70 µm long. Trilocular pores each 4–5 µm in diameter. Enlarged tubular ducts totalling 90–144 on dorsum, each duct 33–40 µm long, 6–8 µm wide at mid-length, rim of duct opening 10–15 µm in diameter, surrounded by a sclerotised circular area 20–35 µm in diameter, enclosing 1 or 2 oval discoidal pores (each pore usually adjacent to rim of duct opening) and with 2–7 (generally 2 or 3) setae, each 17–43 µm long, usually either within rim of duct opening (especially on abdomen) or on edge of rim (especially on head); ducts distributed marginally in clusters of 1–4 on head and thorax, on margins of all abdominal segments in groups of 2–5, but with 6–9 ducts on each side of abdominal segment VII, and also 10–16 medially to submarginally on head and thorax, and 8–14 medially to submarginally on abdominal segments.

Venter. Body setae slender, each 15–225 µm long, longest setae medially on head; apical seta of anal lobe 275–343 µm long. Multilocular disc pores present on posterior abdominal segments only: 0 or 1 (generally none) pores on segment VI, 9–15 on segment VII, 6–16 on segments VIII + IX; each pore 7.5–10.0 µm in diameter. Trilocular pores each 4–5 µm in diameter. Minute discodial pores each 2.5–3.0 µm in diameter, almost always associated with oral-collar tubular ducts, with 1 or 2 pores very close to (but never touching) rim of most oralcollar tubular ducts, with 1 or 2 pores present among the small oral-collar tubular ducts clusters. Oral-collar tubular ducts on most of venter (excluding margins of posterior abdomen) each 8–13 µm long, 2.5–4.0 µm wide, totalling 74–88, distributed as follows: 23–30 on head and thorax, and on abdominal segments: 12–16 total on segments I–III, 2–5 on IV; 3–8 on V; 3–6 on VI; 2–4 on VII, and none on VIII. Small oral-collar tubular ducts each 6.0–8.0 µm long, 2.5 µm wide, distributed in up to 15 marginal clusters on each side of body as follows: 6–29 on head at base of antennae (these often in 2 clusters), 4–16 per cluster on thoracic segments, 6–22 on abdominal segment I; 5–16 on II; 5–15 on III; 7–16 on IV; 3–29 on V; 3–26 on VI; 8–27 on VII; 0–12 on VIII.