Fergusobia floribundae, Davies, Kerrie A., Giblin-Davis, Robin M., Ye, Weimin, Taylor, Gary S. & Thomas, W. Kelley, 2013

Davies, Kerrie A., Giblin-Davis, Robin M., Ye, Weimin, Taylor, Gary S. & Thomas, W. Kelley, 2013, Nematodes from galls on Myrtaceae. V. Fergusobia from large multilocular shoot bud galls from Angophora and Eucalyptus in Australia, with descriptions of six new species, Zootaxa 3741 (1), pp. 101-140 : 119-122

Fergusobia floribundae n. sp. Davies

( Figs 6 , 9 A, 10A)

Measurements. Table 5 .

Holotype Parthenogenetic females Males Infective females

Parthenogenetic

female

n 18 23 7 V% 80.4 84.1±3.5 (79.3–92.2) 80.1±2.2 (76.9–83.2) T% 68.0±16.5 (43.0–90.0)

Material examined. 16 parthenogenetic ♀, 7 pre-parasitic infective ♀, and 23 ♂; roadside vegetation, Frog Rock, near Mudgee, NSW, Australia (32°28´S 149°25´E), and a tree in a cultivated agricultural field at Breeza, NSW (31º 15’S 150º 27’E). Taken from multilocular shoot bud galls on Angophora floribunda . Coll. KA Davies, 15.i.2004; and KA Davies, 29.xii.1998.

Holotype: A parthenogenetic female, on a slide with an infective female and a male paratypes, deposited in the ANIC, Canberra, ACT, Australia, collected at Frog Rock, near Mudgee, NSW, data as above.

Paratypes: Vouchers (collection data as above) deposited at the WINC, The University of Adelaide, SA, Australia, 4 parthenogenetic ♀, 2 pre-parasitic infective ♀, 7 ♂; the Australian National Museum, Sydney, NSW, Australia 10 parthenogenetic ♀, 2 pre-parasitic infective ♀, and 10 ♂; and at the USDA Nematode Collection, Beltsville, MD, USA 1 parthenogenetic ♀, 1 pre-parasitic infective ♀, and 5 ♂.

Other material examined. 10 parthenogenetic ♀, 6 pre-parasitic infective ♀, and 10 ♂, from gall forms on A. floribunda as above, from Settlers’ Road near St Albans, NSW (33º19.20’S, 150º58.62’E). Collected K.A. Davies and L. Nelson, 19.iv.2010 (WNC 2534). These are deposited in the WINC.

Description. Parthenogenetic female. From multilocular shoot bud galls on A. floribunda . Body C-shaped when heat relaxed, dorsally curved with ventral side convex and most curvature in tail region; body posterior to vulva tapering, straight or dorsally concave; similar in size to amphimictic pre-parasitic female and to male. Cuticle with obscure annules 1–1.5 µm wide, longitudinal striations apparent when viewed with light microscope; lateral fields not seen.

Cephalic region offset, frequently retracted when heat-killed, diameter ~65–70 % of body diameter immediately posterior, ~2 µm long, unstriated; rounded outline and flat circum-oral area in lateral view. Stylet with cone comprising 40% of total length, basal knobs ~2 µm across at base, rounded, longer than wide.

Orifice of dorsal pharyngeal gland 1 µm posterior to stylet knobs. Anterior fusiform part of digestive tract diameter 52–88% (mean 62) of body diameter (n = 7), length 2–3.1 times diameter. Lumen of tract broadening at ~50% length of dorsal pharyngeal gland. Pharyngeal glands enormous, occupying ~80% of body diameter, extending 34–56% (mean 42) of total body length.

Secretory/excretory pore opening opposite nucleus of pharyngeal gland, with obscure duct leading to large, ellipsoid secretory/excretory cell 10 µm long and ~2 µm beneath cuticle. Hemizonid extending over 1–2 annules, 1 annule anterior to secretory/excretory pore.

Reproductive tract variable in length, extending to nerve ring in most specimens; outstretched or occasionally with one flexure (in 1 of 16 specimens examined); oviduct with oocytes not in rows; uterus containing no eggs or one egg (in 8 of 16 specimens); vulva with protruding lips, flat or a depressed slit. Anus flat or opening into a cuticular depression. Tail relatively slender, conoid, curved, length 1.7–2.6 times anal body diameter, tip rounded.

Infective pre-parasitic female. From shoot bud gall on A. floribunda . Infecting mature larval stage of Fergusonina sp. or pupa. Arcuate shape when relaxed by heat, dorsally curved with ventral side convex and greater curvature posterior to vulva; maximum body diameter at mid-body length, barely narrowing posterior to vulva. Cuticle with obscure annules not measured, longitudinal striations apparent when viewed with light microscope; lateral fields not seen.

Cephalic region barely offset, up to 2 µm long; circum-oral area flat; stylet with strong shaft; basal knobs ~2 µm across, longer than wide, rounded; cone not seen.

Orifice of dorsal pharyngeal gland 1µm posterior to stylet knobs. Anterior fusiform part of digestive tract diameter 40–50% of body diameter, length 2.9–3.8 times diameter. Pharyngeal glands occupying 18–31% of body diameter, extending over intestine to average 23 (18–35) % body length.

Secretory/excretory pore usually opening posterior to pharyngeal glands; duct obscure, opening onto slightly raised cuticle; secretory/excretory cell ellipsoid, ~10 µm long. Hemizonid not seen.

Uterus packed with sperm in inseminated female; vagina angled slightly towards tail, plugged with refractive material; reproductive tract extending to nerve ring; sometimes hypertrophied in length. Vulval lips almost flat. Tail broad, curved, length 0.7–1.3 times diameter at anus, tip almost hemispherical.

Parasitic female. From haemolymph in abdomen of adult female Fergusonina sp. Larger than other stages (0.92–1.16 mm long); non-motile. Dorsally curved when heat-killed; stout (a = 6.2–6.9). Head not offset. No stylet; no cuticle apparent; oesophagus, intestine and rectum degenerate. Reproductive tract single, greatly hypertrophied, many reflexes with sections running almost entire body. Vulva a transverse slit at 82% body length.

Male. From multilocular shoot bud galls on A. floribunda . Body arcuate when heat relaxed, tail region more or less curved ventrally, concave on ventral side. Cuticle with obscure annules not measured, strong longitudinal striations apparent when viewed with light microscope; lateral fields not seen.

Cephalic region offset, ~2 µm long; circum-oral area flat or slightly elevated, with lightly sclerotised framework; stylet with cone ~50% of total length, stylet knobs ~2 µm across, longer than wide, rounded. Anterior fusiform part of digestive tract diameter 42–70 % (mean 60) of body diameter (n = 7), length 2.2–3.2 times diameter. Pharyngeal glands occupying 31–85% (mean 50) of body diameter, extending over intestine to 18–38% (mean 24) of total body length.

Secretory/excretory pore opening at ~70% of length of pharyngeal gland; duct obscure; secretory/excretory cell not seen. Hemizonid difficult to see, extending over 2 or 3 annules, 4 or 5 annules anterior to secretory/ excretory pore.

Reproductive tract with single testis, variable in length, usually overlapping dorsal pharyngeal gland, sometimes extending to nerve ring, sometimes not reaching posterior end of gland; outstretched or reflexed near nerve ring or posterior to pharyngeal gland; testis, seminal vesicle and vas deferens sometimes clearly differentiated (in 3 of 23 specimens) but mostly not differentiated. Bursa smooth, peloderan; prominent or obscure; arising 23 – 55% along length of body from tail tip. Spicules paired, angular near middle, moderately sclerotised; manubrium not offset, slightly wider than shaft; blade narrowing gradually with a small notch on the anterior side, opening sub-terminal. Inconspicuous muscles associated with cloaca. Tail ventrally curved, length 1–2.5 times diameter at cloaca, tip bluntly rounded.

Diagnosis and relationships. Fergusobia floribundae n. sp. is morphologically characterized by the combination of a C-shaped parthenogenetic female with a narrow, arcuate, conoid tail; an arcuate infective female with an hemispherical tail tip; and an arcuate or J-shaped male with angular spicules and short to mid-length peloderan bursa.

Morphologically, the parthenogenetic female of Fergusobia floribundae n. sp. is most similar to those of F. delegatensae n. sp., F. diversifoliae n. sp., F. morrisae , F. minimus n. sp., and F. pimpamensis n. sp. The infective female is most similar to F. pimpamensis n. sp. The male is most similar to F. pimpamensis n. sp.

From phylogenetic analyses based on sequences of D2/D3 and COI, F. floribundae n. sp. is genetically close to Fergusobia spp. isolated from various gall forms on C. ptychocarpa ( F. ptychocarpae ), Eucalyptus spp. (Vs 37, 328, 38), and A. near woodsiana ( F. pimpamensis n. sp.).

The body shape of the parthenogenetic female of F. floribundae n. sp. (C-shape) differs from F. curriei , F. fisheri , F. porosae , F. nervosae , and F. quinquenerviae (open C-shape); from F. camaldulensae , F. pohutukawa , and F. viridiflorae (arcuate to open C-shape); from F. fasciculosae (arcuate) and from F. r i l e y i (almost straight to arcuate). The stylet (6–7 µm) is shorter than in all other described species of Fergusobia except F. juliae (5–7 µm) and F. minimus n. sp. (4–8 µm). In length (352–466 µm), the female is smaller than those of F. indica (525–626 µm); but larger than those of F. cajuputiae (221–273 µm), F. fasciculosae (237–285 µm), F. fisheri (228–305 µm), F. jambophila (195–300 µm), F. leucadendrae (205–303 µm), (262–347 µm), F. nervosae (245–309 µm), F. philippinensis (229–310 µm), F. quinquenerviae (224–324 µm), and F. viridiflorae (259–328 µm). Parthenogenetic females of F. juliae are difficult to separate from F. floribundae n. sp., because they are variable in shape and form: F. floribundae n. sp. mostly has a longer reproductive system, and the circum-oral area is less raised. The parthenogenetic female of F. floribundae n. sp. has a more posterior hemizonid (1 annule anterior to the secretory/ excretory pore) than F. pimpamensis n. sp. (4–5 annules anterior). It is also very similar to those of F. minimus n. sp., but the cephalic region of the latter is never retracted when heat relaxed as it is in F. floribundae n. sp.

In shape (arcuate to J), the infective female of F. floribundae n. sp. differs from that of F. brittenae , F. cosmophyllae n. sp., F. curriei , and F. pimpamensis n. sp. (open C-shape); from F. eugenioidae , F. juliae , F. morrisae , and F. ptychocarpae (strongly curved in posterior region); and from F. rileyi (almost straight). In length F. floribundae n. sp. infective females (357–450 µm) are shorter than those of F. magna (537–633 µm); and longer than those of F. cajuputiae (239–309 µm), F. dealbata (307–347 µm), F. fasciculosae (268–332 µm), F. leucadendrae (227–291 µm), F. microcarpae (302–341 µm), F. nervosae (282 µm), F. porosae (277–300 µm), F. quinquenerviae (259–325 µm), and F. viridiflorae (321 µm). The ratio a (10.7–13.6) is larger than in F. brevicauda (8.9–10.6) and F. cosmophyllae n. sp. (4–6.8). The shape of the anterior fusiform part of the digestive tract of F. floribundae n. sp. is more slender (length 3–4 times diameter) than that of F. minimus n. sp. (length ~2 times diameter). Stylet length (5–8 µm) is shorter than in F. diversifoliae n. sp. (9–11 µm). The body posterior to the vulva (arcuate with a hemispherical tip) differs in shape from that of F. camaldulensae and F. delegatensae n. sp. (less curved), and F. philippinensis (sub-truncate tip). Fergusobia fisheri has a mostly longer pharyngeal gland (morphometric ratio b’ 3.2–5.7) than F. floribundae n. sp. (b’ 1.9–3.5).

The male shape of F. floribundae n. sp. (arcuate to J), differs from that of F. p oro s a e and F. jambophila (almost straight). In total body length (403–570 µm), it is longer than F. cajuputiae (286–364 µm), F. fasciculosae (274– 336 µm), F. jambophila (200–390 µm), F. leucadendrae (254–350 µm), F. microcarpae (311–398 µm), F. nervosae (277–312 µm), F. philippinensis (280–390 µm), F. porosae (270–326 µm), and F. quinquenerviae (256–329 µm). The male F. floribundae n. sp. lacks the raised circum-oral area seen in F. magna , F. camaldulensae , F. eugenioidae , and F. juliae . The length of the pharyngeal glands relative to the total body length of F. floribundae n. sp. (b’ 2.7–5.6, mean 4.1) is variable, but is mostly shorter than in F. curriei (2.3–3.7) and F. fisheri (2.3–3.4), to which the male is otherwise morphologically similar. The stylet (5–8 µm) is shorter than in F. pohutukawa (10–11 µm) and F. rileyi (11–13 µm). The tail shape (arcuate with a broadly rounded tip) of these nematodes differs from that of F. viridiflorae (more slender), from F. cosmophyllae n. sp. (broader), and from F. philippinensis (truncate tip). The ratio c (8.7–21.8) of male F. floribundae n. sp. reflects its variability in tail length (19–56 µm), but is always larger than in F. ptychocarpae (7.6–8.6). The spicules are strongly sclerotised in F. brevicauda , F. brittenae and F. dealbatae , but not in F. floribundae n. sp. The short to medium length bursa (23–55%), of male F. floribundae n. sp. differs from that of F. delegatensae n. sp. (~90%), F. diversifoliae n. sp. (>80%), F. morrisae (75–83%), and F. pimpamensis n. sp. (60–80%) (all longer), and from F. minimus n. sp. (12–28%) (which is shorter). The edges of the bursa are crenate in F. tumifaciens , but not in F. floribunda n. sp.

Etymology. Named after Angophora floribunda , the host plant from which the nematodes were collected.

Figures

FIGURE 6. Fergusobia floribundae n. sp. ex A. floribunda (all in lateral view): A, Entire parthenogenetic female; B, Head of parthenogenetic female; C, Habitus; D, Tails of parthenogenetic females; E, Entire infective female; F, Head of infective female; G; Habitus; H, Tails of infective females; I, Entire male; J, Head of male; K, Habitus; L, Tails of males. Scale bars: A, E, I = 50 µm. B, F, J = 5 µm. Tails not drawn to scale.

FIGURE 9. Habitus drawings of Fergusobia spp. collected from large multilocular leaf bud galls: A— F. floribundae n. sp. from Angophora floribunda; B— F. pimpamensis n. sp. from Angophora sp; C—undescribed species from E. nr. acmenioides; D—undescribed species from E. amygdalina; E— F. delegatensisae n. sp. from E. delegatensis; F—undescribed species from E. pauciflora; G—undescribed species from E. racemosa; H—undescribed species from E. obliqua; I— F. diversifoliae n. sp. from E. diversifolia; J—undescribed species from E. blakelyi; K— F. brittenae from E. camaldulensis; L—undescribed species from E. dealbata; M— F. minimus n. sp. from E. tereticornis; N— F. cosmophyllae n. sp. from E. cosmophylla; O—undescribed species from E. robusta; P—undescribed species from Eucalyptus sp. at Woodburn, NSW. Scale bars = 50 µm.

Tables

TABLE 5. Measurements (µm) of Fergusobia floribundae n. sp. from large multilocular shoot bud galls on A. floribunda. (mean ± standard deviation (range )).

Length	416	400±40 (352–466)	487±41 (403–570)	409±36 (357–450)
a	10.2	9.9±1.4 (7.9–13.3)	12.3±1.2 (10.2–14.3)	12.0±0.9 (10.7–13.6)
b’	2.8	2.4±0.3 (1.8–2.9)	4.1±0.9 (2.7–5.6)	4.4±1.1 (3.2–5.7)
c	13.2	12.6±2.3 (8.9–16.5)	11.5±2.6 (8.7–21.8)	16.2±2.6 (11.0–18.1)
c’	2.1	2.1±0.3 (1.7–2.6)	2.0±0.3 (1.0–2.7)	1.0±0.2 (0.7–1.3)