Fergusobia juliae, Davies, Kerrie, Giblin-Davis, Robin, Ye, Weimin, Taylor, Gary & Thomas, Kelley, 2012

Davies, Kerrie, Giblin-Davis, Robin, Ye, Weimin, Taylor, Gary & Thomas, Kelley, 2012, Nematodes from galls on Myrtaceae. III. Fergusobia from flower bud and stigma galls on Eucalyptus, with descriptions of four new species, Zootaxa 3532, pp. 1-36 : 15-20

Description of Fergusobia juliae n. sp. Davies

( Figs 5 , 7 C, 8B)

Measurements. See Table 4 .

Material examined. The description presented here is based on measurements of 29 parthenogenetic females, 20 males, and 19 infective females from flower bud galls on Eucalyptus macrorrhyncha F. Muell ex Benth. , associated with Fn. nicholsonii ; from the Spring Gully Conservation Park, Clare, South Australia (33°54´S 138°33´E), collected by Julia Giblin and Kerrie Davies, 4.viii.1999.

Holotype. Parthenogenetic female, with a paratype 3 and infective Ƥ, on a slide deposited at the Australian National Insect Collection ( ANIC), Canberra, Australian Capital Territory, Australia, collection data as above.

Paratypes. Vouchers deposited at the Waite Insect and Nematode Collection ( WINC), the University of Adelaide, Adelaide, South Australia; and the USDA Nematode Collection, Beltsville MD, USA. Collected from two locations: Spring Gully Conservation Park, Clare, South Australia, 33°54´S 138°33´E, coll. Kerrie Davies, 18.vi.1999 ( WINC slides number 004310); the Australian National Botanic Gardens, Black Mountain, Canberra, ACT, 35°20´S 148°57´E, coll. Kerrie Davies and Mike Hodda, 15.ix.2003.

Description. Parthenogenetic female. Body arcuate to C-shaped when heat relaxed, dorsally curved with ventral side convex, and most curvature in tail region; smaller than amphimictic pre-parasitic females and males; body narrowing behind vulva. Cuticle with obscure annules, spacing not measured; longitudinal striae apparent when viewed with light microscope; lateral fields not seen.

Cephalic region ~70–85% diameter of body at anterior end, offset, unstriated, 1–2 µm long; in lateral view with rounded outline and circum-oral area flat or raised. Small stylet with conus 40–50% of length, basal knobs well defined, ~2µm wide at base, round.

Orifice of dorsal oesophageal gland 1–2 µm posterior to stylet knobs. Anterior fusiform part of digestive tract diameter 59 (44–74) % of body diameter, length 2.2–3.5 (mean 2.7) times diameter; lumen of tract broadening at ~50–70% length of dorsal oesophageal gland. Oesophageal glands large to enormous, diameter ~70–85% of body diameter, extending over intestine, distance from head to end of glands 42 (28–52)% of total body length. Secretory/excretory system with prominent duct; secretory/excretory cell not seen. Hemizonid extending over one annule, 2 annules anterior to pore.

Reproductive tract variable in length, extending to distal end of dorsal oesophageal gland or part-way along, usually reflexed posterior to the gland, up to three flexures; cap cell offset in some specimens; oviduct with oocytes not in rows; uterus containing no eggs (in 12 of 19 specimens examined), less frequently one egg (in 6 specimens) or three eggs (in 1 specimen); vulva a depressed slit, flat or occasionally with protruding lips (in 1 of 19 specimens). Tail short, conoid, varying from relatively slender to approximating an equilateral triangle; length 1–2 times anal body diameter, bluntly rounded tip.

Infective pre-parasitic female. Infecting mature larval stage of Fergusonina nicholsoni . Body arcuate or Jshaped when heat-relaxed, dorsally curved with ventral side convex behind vulva; maximum diameter at mid-body length; body narrowing gradually posterior to tail. Cuticle appearing smooth, with inconspicuous annules, spacing not measured; longitudinal striae apparent when viewed with light microscope; lateral fields not seen.

Cephalic region occupying 67–80% of body diameter at anterior end, continuous or barely offset; circum-oral area flat; stylet slender, weakly sclerotised with basal knobs slightly longer than wide, rounded, ~1.5 µm diameter; conus 50% of total length.

Orifice of dorsal oesophageal gland ~1µm posterior to stylet knobs; oesophageal glands diameter 30–50% body diameter, extending over intestine, distance from head to end of glands on average 20 (13–28)% of total body length. Anterior part of digestive tract diameter ~30% of body diameter, barely fusiform.

Secretory/excretory pore opening posterior to oesophageal glands; duct obscure; secretory/excretory cell not seen. Hemizonid not seen.

Uterus packed with sperm in inseminated females; vagina at angle of ~45° anterior to body axis; reproductive tract extending part way along dorsal oesophageal glands or to nerve ring, hypertrophied in some specimens. Vulval lips flat or sometimes slightly raised, surrounded by a plate of cuticle. Tail length 1–2 times diameter at anus, tip bluntly rounded or almost hemispherical.

Male. Body J-shaped when heat-relaxed, with posterior one-third of body more or less curved ventrally, dorsal side convex. Cuticle with obscure annules, ~1 µm spacing, longitudinal striae apparent when viewed with light microscope; lateral fields not seen.

Cephalic region occupying 33–70% of body diameter at anterior end, offset, ~2 µm long; circum-oral area raised, with lightly sclerotised framework; weak stylet with conus 40% of total length, round stylet knobs 2 µm diameter. Orifice of dorsal oesophageal gland opening 1–2 µm posterior to stylet knobs.

Anterior fusiform part of digestive tract diameter 33–71% of body diameter, length 2.4–3.7 (mean 3, n = 9) times diameter. Oesophageal glands diameter ~70–80% of body diameter, extending over intestine, distance from head to end of glands 26–43% (mean 34%) of total body length. Lumen of intestinal tract broadening from ~30% of length from anterior to behind oesophageal glands.

Secretory/excretory pore opening at level of nucleus of dorsal oesophageal gland, duct obscure; secretory/ excretory cell not seen. Hemizonid extending over one or two annules, four or five annules anterior to secretory/ excretory pore.

Reproductive tract with single testis, variable in length, tip located at half to two-thirds distance along body, and ending posterior to the dorsal oesophageal gland except in two specimens where it overlapped the gland; straight or occasionally reflexed (4 of 20 specimens); testis, seminal vesicle and vas deferens not clearly differentiated. Bursa smooth; may be prominent or obscure; arising 23 – 39% along length of body anterior to tail tip. Spicules angular near their middle, robust, strongly sclerotised; manubrium not offset, slightly wider than shaft; blade narrowing gradually with notch behind the tip on proximal edge; opening terminal. Inconspicuous muscles associated with cloaca. Tail usually ventrally concave, length 1–2.7 times diameter at cloaca; bluntly rounded.

Diagnosis and relationships. Fergusobia juliae n. sp. is morphologically characterized by the combination of an arcuate to C-shaped parthenogenetic female with a short, broadly conoid tail, a J-shaped infective female with a hooked tail region, a broadly rounded tail tip and a cuticular plate around the vulva, and J-shaped males with angular spicules and a short peloderan bursa.

Parthenogenetic females of F. juliae n. sp. are morphologically similar to those of F. eugenioidae n. sp., F. curriei and F. f i s h e r i. Infective females are morphologically similar to those of F. eugenioidae n. sp. and F. morrisae n. sp., but differ in having a cuticular plate around the vulva. Males are similar to F. brittenae and F. curriei .

Parthenogenetic females of F. juliae n. sp. (arcuate to C-shape) differ in shape from those of F. rileyi (almost straight). They are shorter (292–385 µm), than those of F. indica (525–626 µm) and F. magna (418–780 µm), and longer than those of F. cajuputiae (221–273 µm) and F. fasciculosae n. sp. (237–285 µm). The stylet (5–7 µm) is shorter than in F. philippinensis (7.5–9 µm), F. fisheri (9–10 µm), F. ptychocarpae (8–13 µm), and F. eugenioidae n. sp. (9–11 µm). The large to enormous oesophageal glands (b’ 1.9–3.6), are similar to those in most described species, but differ from those of F. brevicauda and F. jambophila which have smaller glands, and from F. quinquenerviae and F. viridiflorae which have an extra lobe or reflex. The shape of the body posterior to the vulva in F. juliae n. sp. (conoid, arcuate, with a bluntly rounded tip) differs from that of F. p o h u t u k a w a (straight, conoid, with a narrowly rounded tip), and parthenogenetic females of F. quinquenerviae , F. cajuputiae , F. dealbatae , F. leucadendrae , F. nervosae , and F. viridiflorae from the M. leucadendra complex which have broadly rounded tail tips (Davies & Giblin-Davis 2004). The tail is shorter (10–11 µm) than in F. tumifaciens and F. camaldulensae (15–29 µm and 21–36 µm, respectively). The tail tip is more broadly rounded than in F. c u r r i e i. Parthenogenetic females of F. juliae n. sp. are separated from F. brittenae by the position of the hemizonid (1 vs 5–6 annules anterior to the secretory/excretory pore), and the absence of the large excretory cell present in F. brittenae . They are morphologically close to those of F. morrisae n. sp., but have mostly smaller stylets (5–7 µm vs 7–8 µm).

Infective females of F. juliae n. sp. are strongly curved posterior to the vulva, and are similar to F. eugenioidae n. sp., F. morrisae n. sp., and F ptychocarpae . They differ in shape from F. magna and F. c a m a l d u l e n s a e (arcuate); F. nervosae (open C) and F. brittenae , F. curriei and F. r i l e y i (almost straight). They are longer (396–550 µm) than F. c a j u p u t i a e (239–309 µm), F. dealbatae (307–347 µm), F. fasciculosae n. sp. (268–332 µm), F. leucadendrae (227–291 µm), F. philippinensis (290–370 µm), and F. quinquenerviae (259–325 µm). The shape of the body posterior to the vulva (strongly curved, with tail tip almost hemispherical) differs from F. brevicauda , F. f i s h e r i and F. viridiflorae (less curved), and from F. ptychocarpae (tail tip bluntly rounded). The tail is longer (26–44 µm), than in F. fasciculosae n. sp. (13–25 µm). The infective females of F. juliae n. sp. and F. eugenioidae n. sp. can be separated by having flat vs peaked circum-oral areas, and by the presence vs absence of a vulval plate, respectively. The diameter of the anterior fusiform part of the digestive tract separates infective females of F. juliae n. sp. and F. morrisae n. sp., occupying 13–28% vs 35–55% of the body diameter, respectively.

Males of F. juliae n. sp. are J-shaped, differing from those of F. pohutukawa and F. rileyi (almost straight to arcuate); from F. eugenioidae n. sp. (arcuate to just J-shape); and from F. jambophila (almost straight). The males are longer (377–453 µm), than those of F. c a j u p u t i a e (286–364 µm), F. fasciculosae n. sp. (274–336 µm), F. leucadendrae (254–350 µm), F. nervosae (277–312 µm), and F. quinquenerviae (256–329 µm). The ratio ‘a’ (11.1–15.3) of males of F. juliae n. sp. is greater than in F. morrisae n. sp. (8.5–10.7). Tail shape (arcuate, broadly rounded tip) differs from that of F. magna (more slender), and F. philippinensis (truncate tip). The tail (22–65 µm) is mostly longer than in F. brevicauda (28–35 µm). F. juliae n. sp. males have a short reproductive system like F. brittenae that does not reach the oesophageal gland, differing from F. c u r r i e i and F. dealbatae with long reproductive systems. The spicules of F. juliae n. sp. are longer (20–27 µm) than in F. fisheri (16–20 µm). The angular shape differs from that in F. jambophila , where it is arcuate. The short bursa (23–39% body length) differs from F. camaldulensae , F. ptychocarpae , and F. viridiflorae (with longer bursae). The bursa is smooth in F. juliae n. sp., but crenate in F. t u m i f a c i e n s. Males of F. juliae n. sp. lack the large excretory cell of F. brittenae .

The status of F. juliae n. sp. is supported as a new species by its sequence divergence based upon phylogenetic analyses of sequences of D2/D3 and COI ( Figs 1 , 2 ). Phylogenetic analyses ( Figs 1 , 2 ) suggest that F. juliae n. sp. is close to Fergusobia spp. from FBGs on E. microcarpa (voucher 1, MSp 22) and E. fibrosa ( F. morrisae n. sp.), stigma galls on E. fasciculosa ( F. fasciculosae n. sp.), and pea galls on E. gomphocephala (voucher 63, MSp 9) and Eucalyptus sp. The blast search of the 859 bp sequenced from D2/D3 revealed the highest matches with vouchers 1 (MSp 22), 2 (MSp 27), 31 (MSp 29), 32 (MSp 28), 34 (MSp 30), 63 (MSp 9), 65 ( F. fasciculosae n. sp.), 68 and 314 (MSp 17), 71 (MSp 16), 275 (MSp 6), and 273 and 347 (MSp 11) with 97–99% identity, 3–27 bp differences, and 1–11 gaps. The blast search of the 618 bp sequenced from COI revealed the highest matches as vouchers 2 (MSp 27) and 67 (MSp 12), with 97–98% identity, 12–16 bp differences and no gaps.

Etymology. Named for Julia I. Giblin, who found the galls on E. macrorrhyncha at Spring Gully Conservation Park.

Figures

FIGURE 1. The Bayesian consensus tree inferred from D 2 / D 3 under TVM + I + G model (lnL = 4001.6121; freqA = 0.2903; freqC = 0.1443; freqG = 0.2394; freqT = 0.3259; R (a) = 0.8475; R (b) = 3.4236; R (c) = 1.9889; R (d) = 0.455; R (e) = 3.4236; R (f) = 1; Pinva = 0.522; Shape = 0.5933). Posterior probability values exceeding 50 % are given on appropriate clades. (Tree labels comprise nematode species, location (Australia state code), gall type, host plant species and GenBank accession number.

FIGURE 2. The Bayesian consensus tree inferred from COI under GTR + I + G model (lnL = 3999.9661; freqA = 0.2104; freqC = 0.1017; freqG = 0.1948; freqT = 0.4931; R (a) = 1.2258; R (b) = 7.2392; R (c) = 1.5064; R (d) = 0.0698; R (e) = 4.1806; R (f) = 1; Pinva = 0.5476; Shape = 1.5992). Posterior probability values exceeding 50 % are given on appropriate clades.

FIGURE 5. Fergusobia juliae n. sp. (all in lateral view): A, Entire infective female; B, Head of infective female; C, Tails of infective females; D, Entire parthenogenetic female; E, Head of parthenogenetic female; F, Tails of parthenogenetic females; G, Entire male; H, Head of male; I, Tails of males. Scale bars: A, D, G = 50 μm. B, E, H = 5 μm. Tails not drawn to scale. Line drawings indicate ranges of habitus of the various stages.

FIGURE 7. Habitus drawings of Fergusobia spp. (most undescribed) collected from flower bud galls (P and Q redrawn from Siddiqi 1994): A, F. ptychocarpae from C. ptychocarpa; B, F. eugeniodae n. sp. from E. eugenioides; C, F. j u l i a e n. sp. from E. macrorrhyncha; D, MSp 27 from E. obliqua; E, MSp 65 from E. obliqua; F, MSp 64 from E. pauciflora; G, F. tumifaciens from E. bridgesiana (formerly stuartiana); H, MSp 54 from E. tereticornis; I, F. fasciculosae n. sp. from E. fasciculosa; J, F. morrisae n. sp. from E. fibrosa; K, MSp 71 from E. largiflorens; L, MSp 72 from E. melliodora; M, Msp 22 from E. microcarpa; N, Msp 75 from E. populnea; O, Msp 62 from E. pruinosa; P, F. brevicauda from E deglupta; Q, F. philippinensis from E. deglupta. Scale bars = 50 μm. MSp numbers as in Davies et al. (2012).

Tables

TABLE 4. Measurements (µm) of Fergusobia juliae n. sp. from E. macrorrhyncha (mean ± S. D. (range )).

	Holotype Parthenogenetic females	Males	Infective females
n	1 19	20	19
Length	322 337±25.0 (292–385)	423±25.4 (377–453)	481±45.0 (396–550)
a	9.7 8.9±0.5 (7.5–10.7)	12.9±1.2 (11.1–15.3)	12.3±1.2 (9.7–14.9)
b’	2.0 2.4±0.5 (1.5–3.3)	2.9±0.5 (2.3–3.8)	5.1±1.1 (3.6–6.2)
c	15.8 14.9±2.2 (12.5–19.9)	11.7±2.4 (8.7–13.3)	14.3±1.2 (12.0–16.9)
c’	1.1 1.5±0.4 (0.9–2.1)	1.7±0.4 (1.0–2.7)	1.6±0.2 (1.2–2.0)
V %	83.9 83.8±3.2 (80.3–94.9)		79.2±1.1 (77.3–81.8)
T %		55.2±10.9 (43–85)
Body diameter	33 38±2.7 (33–43)	33±2.3 (30–35)	39±3.4 (30–44)
Stylet length	7 6.4±1.1 (5–7)	8.1±1.8 (7–11)	7.2±2.0 (6–10)
Ant. end to SE pore	113 92±8.9 (83–113)	98±14.0 (63–133)	109±17.7 (72–133)
Spicule length		23.8±2.0 (20–27)
Tail length	20 23±4.0 (15–29)	38±9.2 (22–65)	34±4.1 (26–44)