Fergusobia delegatensae, 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 : 111-115

Fergusobia delegatensae n. sp. Davies

( Figs 3 , 4 , 9 E, 10E)

Measurements. Table 3.

Holotype Parthenogenetic females Males Infective females

Parthenogenetic female

n 5 21 4

Length 374 387±30.7 (345–427) 417±59.0 (350–518) 414±33.2 (375–452) a 9.5 9.5±0.7 (8.4–10.3) 11.0±1.3 (8.9–13.0) 11.0±0.7 (10.5–12.0) b’ 1.9 1.9±0.1 (1.8–2.0) 3.0±0.4 (2.3–3.8) 3.1±1.2 (1.9–4.4) c 23.4 24.2±2.0 (21.6–27.1) 9.6±1.1 (7.5–11.3) 14.1±4.0 (11.5–20.0) c’ 1.7 1.4±0.3 (1.2–1.7) 2.0±0.3 (1.4–2.5) 1.0±0.2 (0.8–1.2) V% 86.2 86.2±0.6 (85.4–87.0) 85.0±3.4 (82.7–90.0) T% 74.7±4.6 (61.9–80.7)

Body diameter 39 41±2.3 (39–45) 38±2.3 (33–41) 38±1.5 (36–39) Stylet length 10 8±1.0 (8–10) 10±1.1 (8–11) 10±1.3 (8–11) Material examined. 5 parthenogenetic ♀, 4 pre-parasitic infective ♀ and 21 ♂; roadside vegetation, Ben Lomond National Park, Tasmania, Australia (41°30´S 147°45´E). From multilocular shoot bud galls on Eucalyptus delegatensis . Coll. K.A. Davies, 11.xi.2002.

Holotype: Parthenogenetic female, on a slide together with one infective female and a male paratype; deposited in the ANIC, Canberra, ACT, Australia, collection data as above.

Paratypes: (collection data as above) deposited at the WINC, The University of Adelaide, SA, Australia, 1 parthenogenetic ♀, 1 pre-parasitic infective ♀, and 10 ♂; the Tasmanian Museum and Art Gallery, Hobart, TAS, Australia, 2 parthenogenetic ♀, 1 pre-parasitic infective ♀, and 9 ♂; and the USDA Nematode Collection, Beltsville, MD, USA 1 parthenogenetic ♀, 1 pre-parasitic infective ♀, and 1 ♂.

Description. Parthenogenetic female. From multilocular shoot bud galls on E. delegatensis . Open C-shape when heat relaxed, dorsally curved with ventral side convex; similar in size to amphimictic pre-parasitic female and to male; cuticle with obscure annules, ~1 µm wide, longitudinal striations apparent when viewed with light microscope; lateral fields not seen.

Cephalic region diameter 64–77 % of diameter immediately posterior, offset, unstriated; rounded outline in lateral view, 1.8–2.3 µm long; circum-oral area flat. Four fused rounded sectors separated by two wider and two narrower flatter sectors, i.e., 8 lips visible with SEM ( Fig. 4 C, D). Stylet with cone 40–50% of total length, basal knobs round, slightly longer than wide, ~2 µm across.

Orifice of dorsal pharyngeal gland 1–2 µm posterior to stylet knobs. Anterior fusiform part of digestive tract occupying ~45–60% of body diameter, length 2.6 (2.4–2.8) times diameter; lumen of tract broadening near posterior of pharyngeal glands. Pharyngeal glands enormous, occupying ~75% of body diameter, extending 46 (44–50) % of total body length.

Secretory/excretory pore opening at about half length of pharyngeal gland, with duct leading to ellipsoid secretory/excretory cell just beneath body wall. Hemizonid extending over 2 annules, 5 annules anterior to secretory/excretory pore.

Reproductive tract variable in length, extending part-way along dorsal pharyngeal gland; outstretched or with one or two flexures; oviduct with oocytes in rows of two or three, or not in file; uterus containing no eggs or one egg; vulva with protruding lips or a depressed slit. Body narrowing gradually, conoid posterior to vulva. Tail slightly dorsally concave, conoid, length 1.5 times anal body diameter, tip rounded.

Infective pre-parasitic female. From multilocular shoot bud gall on E. delegatensis . Infecting mature larval stage of Fergusonina sp. or pupa. Arcuate shape when relaxed by heat, dorsally curved with ventral side convex; maximum body diameter at mid-body length; anterior and posterior ends with similar shape. Cuticle with obscure annules ~1 µm wide, longitudinal striations apparent when viewed with light microscope; lateral fields not seen.

Cephalic region not offset. Circum-oral area flat. Stylet slender, weakly sclerotised with tiny basal knobs longer than wide; cone 50% of total length.

Orifice of dorsal pharyngeal gland 1–2 µm posterior to stylet knobs. Anterior fusiform part of digestive tract occupying ~40% of body diameter, length ~2.5–8 times diameter. Pharyngeal glands occupying ~30% body diameter, extending over intestine to 32 (23–55) % body length. Post-anal intestinal sac present.

Opening of secretory/excretory pore variable in position relative to pharyngeal glands; secretory/excretory cell not seen. Hemizonid not seen.

Uterus occupying 70% of body length in uninseminated female, packed with sperm in inseminated female; vagina at right angle to longitudinal body axis; reproductive tract extending to nerve ring; sometimes hypertrophied in length and reflexed. Vulval lips small, slightly raised. Tail short, broad, length 0.7–1.2 times diameter at anus, tip almost hemispherical.

Male. From multilocular shoot bud galls on E. delegatensis . Body arcuate to open C-shape when relaxed by heat, tail region more curved ventrally. Cuticle with obscure annules ~1 µm wide, longitudinal striations apparent when viewed with light microscope; lateral fields not seen.

Cephalic region offset (but often retracted when heat-killed), diameter 65–75% of body diameter immediately posterior, 1.2–3 µm long; circum-oral area flat, with lightly sclerotised framework; stylet 8–11 µm long, cone 40% of total length, stylet knobs round 2 µm across. Anterior fusiform part of digestive tract occupying 45–75% of body diameter, length 2.5 (1.6–4.6) times diameter. Orifice of dorsal pharyngeal glands 2 µm posterior to stylet knobs; pharyngeal glands diameter ~45–60% of body diameter, extending over intestine to average 34% (26–43%) of total body length.

Secretory/excretory pore at ~50% of length of pharyngeal gland; duct refractile for first ~5 µm, secretory/ excretory cell not seen. Hemizonid extending over 2 annules, one annule anterior to secretory/excretory pore.

Reproductive tract with single testis, variable in length, sometimes extending to nerve ring but usually overlapping dorsal pharyngeal gland; outstretched or reflexed. Testis, seminal vesicle and vas deferens clearly differentiated, with testis offset and seminal vesicle outstretched with two or three germ cells per row. Bursa smooth or crenate, sometimes longitudinally striated; prominent or obscure; arising 40 – 68% along length of body from tail tip; terminating immediately posterior to cloaca. Spicules paired, arcuate to angular near middle, strongly sclerotised; manubrium wider than shaft with tip rounded or pointed; blade with convex curve on anterior edge, opening terminal. Inconspicuous muscles associated with cloaca. Tail in line with body or more ventrally curved, length 1.5–2.5 times diameter at cloaca; tip bluntly rounded.

Diagnosis and relationships. Fergusobia delegatensae n. sp. is morphologically characterized by the combination of an open C-shaped parthenogenetic female with a broadly conoid tail, an infective female of variable shape with an hemispherical tail tip, and male of open C-shape with a bursa that arises 40–70% along the length of the body and terminates just posterior to the cloaca.

In form, the parthenogenetic female of F. delegatensae n. sp. is closest to those of F. eugenioidae , F. fasciculosae , F. fisheri , F. juliae , F. microcarpae , and F. porosae . The infective female is closest to those of F. brittenae , F. cosmophyllae n. sp., F. diversifoliae n. sp., and F. fasciculosae . The male is closest to those of F. diversifoliae n. sp.

From phylogenetic analyses based on sequences of D2/D3 and COI, F. delegatensae n. sp. is genetically close to Fergusobia spp. isolated from multilocular shoot bud galls on E. amygdalina , E. diversifoliae ( F. diversifoliae n. sp.), and E. racemosa , and from flower bud galls on E. obliqua .

In shape (open C), the parthenogenetic female of F. delegatensae n. sp. differs from those of F. fasciculosae (arcuate); F. brittenae , F. cosmophyllae n. sp., F. floribundae n. sp., F. i n d i c a and F. minimus n. sp. (C-shape); and F. rileyi (almost straight to arcuate). It is longer (345–527 µm) than 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), F. morrisae (262–347 µm), F. nervosae (245–309 µm), F. philippinensis (229–310 µm), F. quinquenerviae (224–324 µm), and F. viridiflorae (259–328 µm). The stylet (8–10 µm) is longer in this parthenogenetic female than in F. floribundae n. sp. (6–7 µm) and F. juliae (5–7 µm); and shorter than in F. camaldulensae (11–13 µm), F. indica (12–15 µm), and F. rileyi (10–13 µm). In having large to enormous pharyngeal glands (b’ 1.8–2), it is similar to most described species, but differs from F. brevicauda , F. magna , and F. tumifaciens which have smaller glands. The position of the vulva (85–87%) is more posterior than in F. curriei (78–84%). The shape of the body behind the vulva of F. delegatensae n. sp. (conoid, arcuate, with bluntly rounded tip) differs from that of F. brevicauda , F. cajuputiae , and F. leucadendrae (arcuate with broadly rounded tip), and from F. dealbata , F. magna , F. morrisae , F. philippinensis , F. pimpamensis n. sp., and F. ptychocarpae (more slender, arcuate or straight tails). Tail length (14–18 µm) is shorter than in F. brittenae (23–37 µm) and F. pimpamensis n. sp. (20–41 µm), and F. pohutukawa (19–35 µm). Ratio a (8.4–10.3) in F. delegatensae n. sp. is larger than in F. pohutukawa (4.4–8.2) and F. tumifaciens (7–8). Ratio c in F. delegatensae n. sp. (21.6–27.1) is larger than F. camaldulensae (9–17.9), F. curriei (9.6–14.9), F. eugenioidae (13–19), F. juliae (12.5–19.9), and F. tumifaciens (10–11). The position of the hemizonid (5 annules anterior to the secretory/excretory pore) separates F. delegatensae n. sp. from F. microcarpae (2–3 annules anterior), F. porosae (2–3 annules anterior), and F. diversifoliae n. sp. (8 annules anterior).

The infective female of F. delegatensae n. sp. is arcuate in shape, differing from F. brittenae , F. curriei and F. magna (open C); F. fisheri (barely J); from F. eugenioidae , F. juliae , F. morrisae , and F. ptychocarpae (strongly curved in posterior region); and F. r i l e y i (almost straight). In length (375–452 µm) it is smaller than F. magna (537– 633 µm); and larger than F. cajuputiae (239–309 µm), F. dealbatae (307–347 µm), F. fasciculosae (268–332 µm), F. leucadendrae (227–291 µm), F. p oro s a e (277–300 µm), and F. quinquenerviae (259–325 µm). Ratio a (10.5–12) of the infective female of F. delegatensae n. sp. is larger than in F. brevicauda (6.5–9.0) and F. cosmophyllae n. sp. (4–6.8). The vulva is more posterior (83–90%) than in F. philippinensis (70–82%). The stylet is longer (8–11 µm) n. sp. than in F. microcarpae (6–7 µm) and F. minimus n. sp. (4–5 µm). The shape of the body behind the vulva in F. delegatensae n. sp. is straight with a hemispherical tip; differing from that of F. microcarpae , F. p o ro s a e, and F. quinquenerviae (straight with broadly rounded tips); F. philippinensis (with a truncate tip); F. nervosae and F. viridiflorae (arcuate with bluntly rounded tail tips); and F. floribundae n. sp. (curved, with hemispherical tips). F. delegatensae n. sp. is separated from F. pimpamensis n. sp. by having an off-set head; and from F. camaldulensae by lacking a peaked circum-oral area.

The male of F. delegatensae n. sp. is arcuate to C-shaped, and differs from F. brittenae , F. curriei , F. juliae , and F. ptychocarpae (J-shape), F. eugenioidae n. sp. and F. tumifaciens (just J-shape); F. pohutukawa and F. rileyi (almost straight to arcuate); and F. porosae and F. jambophila (almost straight). In length (350–518 µm), it is larger than F. fasciculosae (274–336 µm), F. nervosae (277–312 µm), F. p o ro s a e (270–326 µm), and F. quinquenerviae (256–329 µm). The arcuate, conoid shape of the tail differs from that of F. rileyi and F. viridiflorae (more slender, arcuate to straight), and F. philippinensis (arcuate with a truncate tip). The spicule is shorter (18–23.5 µm) than that of F. magna (30–37 µm); and longer than that of F. cosmophyllae n. sp. (12–15 µm) and F. leucadendrae (14–17 µm). In having an angular shape, the spicule differs from that of F. r i l e y i, F. pimpamensis n. sp. and F. jambophila , where it is arcuate. The bursa of F. delegatensae n. sp. ends just posterior to the cloaca, separating it from F. cajuputiae , F. camaldulensae , F. dealbatae , F. diversifoliae n. sp., F. fisheri , F. floribundae n. sp., F. microcarpae , F. minimus n. sp., and F. morrisae , in which it extends to or around the tail tip.

Etymology. Named after Eucalyptus delegatensis , the host plant from which the nematodes were collected.

Figures

FIGURE 3. Fergusobia delegatensae n. sp. ex E. delegatensis (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 4. Scanning electron micrographs of Fergusobia spp. from large multilocular shoot bud galls. A, B F. pimpamensis n. sp.; C, D F. delegatensae n. sp. A, Head (en face); B, vulva and lateral field; C Head (en face); D, Head (lateral view). Scale bars: A, C = 2 µm; B = 10 µm; C = 5 µm.

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.