Fergusobia planchonianae Davies

Davies, Kerrie A., Ye, Weimin, Giblin-Davis, Robin M., Taylor, Gary S., Hodda, Mike & Thomas, W. Kelley, 2014, Nematodes from galls on Myrtaceae. VII. Fergusobia from ‘ leafy’ leaf bud galls in Australia, with re-description of Fergusobia tumifaciens (Currie 1937) Wachek 1955 and descriptions of Fergusobia planchonianae n. sp. and Fergusobia viminalisae n. sp., Zootaxa 3856 (4), pp. 529-554 : 539-543

Description of Fergusobia planchonianae Davies n. sp.

( Figs 4 ; 6A, B; 7D; 8D)

= Fergusobia MSp. 6 apud Davies et al., 2010a Measurements. Table 3 .

Material examined. The description presented here is based on measurements of 14 parthenogenetic ♀s, 5 infective ♀s and 49 ♂ s; North Stradbroke Island, Brisbane, Queensland (2730´ S 15327 ´E). Taken from ‘leafy’ leaf bud galls on Eucalyptus planchoniana F. Muell. 1878 growing in roadside vegetation. Coll. KA Davies, 2.x.2002.

Holotype. One parthenogenetic female, deposited at the ANIC, Canberra, ACT, Australia, collection data as above, on a slide with an infective ♀ and a ♂.

Paratypes. Vouchers (collection data as above) deposited at the WINC, The University of Adelaide, SA, Australia, 5 parthenogenetic females, 2 infective females and 20 males on slides numbered WINC 004263–65, 004543–50, 004555–59 ( WNC 2388, 2289); at the Queensland Museum, Brisbane, Queensland, Australia, 5 parthenogenetic females, 2 infective females and 20 males on slides; and at the USDA Nematode Collection, Beltsville, MD, USA 3 parthenogenetic females and 8 males on slides.

Description. Parthenogenetic female. From ‘leafy’ leaf bud galls on E. planchoniana . Body an open C-shape when heat relaxed, dorsally curved with ventral side convex, particularly posterior to the vulva, in some specimens body is sharply curved behind the vulva with posterior part of body at about 60° angle to anterior part; body narrows gradually posterior to vulva. Similar in size to amphimictic pre-parasitic female and male. Cuticle with obscure annules ca 1 µm wide, longitudinal striae just apparent when viewed with light microscope. Lateral fields 3–5 µm wide, flat, narrowing posterior to vulva and almost reaching tail tip; with many broken, diagonal striae in SEM.

Cephalic region about 75% diameter of body at anterior end, offset, about 1.5–2 µm long, unstriated; with rounded outline in lateral view and circum-oral area flat or slightly raised. First segment behind the cephalic region is longer than those immediately posterior to it. Stylet with conus 40–50% of length, basal knobs rounded, well defined, ca 2 µm wide at base.

Orifice of dorsal pharyngeal gland about 2 µm posterior to stylet knobs. Anterior fusiform part of digestive tract occupying 65–66% of body diameter, length 1.7–3.2 times diameter; with lumen increasing in diameter behind dorsal pharyngeal gland. Pharyngeal glands overlapping intestine, large to enormous, diameter about 50–90% of body diameter, distance from head to end of glands about 40–55% of total body length.

Secretory/excretory pore opposite dorsal gland nucleus, duct prominent; secretory/excretory cell not seen. Hemizonid not seen.

Reproductive tract extending to nerve ring; outstretched, sometimes flexed near nerve ring; oviduct with one or two oocytes per row; uterus non-extensile, containing no eggs or one egg in 2/ 14 specimens; vulva variable either with protruding lips or depressed. Tail short, more or less conoid, often dorsally concave, length 0.5–1 times anal body diameter, with bluntly rounded tip.

Infective pre-parasitic female. From ‘leafy’ leaf bud gall on E. planchoniana . Infecting mature larval stage of Fergusonina sp. or pupa. Body arcuate when relaxed by heat; cylindroid; maximum body width at mid-body length; narrows gradually near tail and head so that each has a similar shape. Cuticle with obscure annules ca 1 µm high, longitudinal striae not apparent when viewed with light microscope; lateral fields not seen.

Cephalic region continuous or barely offset, 0.7–1.5 µm long; circum-oral area flat. Stylet slender, weakly sclerotised with tiny basal knobs ca 1.5 µm wide; conus about 40–50% of length.

Orifice of dorsal pharyngeal gland about 1 µm posterior to stylet knobs; pharyngeal glands diameter about 50% of body width, extending over intestine, distance from head to end of glands 31 (30–33)% of total body length. Anterior fusiform part of digestive tract diameter 50–55% of body diameter, length 2–2.3 times diameter.

Secretory/excretory pore opening opposite pharyngeal gland nucleus; duct obscure; secretory/excretory cell not seen. Hemizonid not seen.

Reproductive tract extending to nerve ring; sometimes hypertrophied; uterus alone comprising 60% of body length in uninseminated females, packed with sperm in inseminated females; vagina perpendicular to body axis; vulval lips flat. Post-anal intestinal sac present. Tail short, broad; 0.8–1.3 times longer than anal body diameter, tip almost hemispherical.

Male. From ‘leafy’ leaf bud galls on E. planchoniana . Body arcuate when heat-relaxed, tail ventrally concave. Cuticle with obscure annules about 1 µm wide, longitudinal striae apparent when viewed with light microscope; lateral fields 4 µm wide at mid-body length, flat, with broken diagonal striae, point of origin obscure.

Cephalic region occupying 70% of anterior body diameter, offset, 1–2 µm long; circum-oral area flat, with lightly sclerotised framework. Stylet 7–10 µm long, with conus 40% of length, with round stylet knobs about 2 µm wide. Anterior fusiform part of digestive tract diameter 40–64% of body diameter, length 1.8–2 times diameter. Orifice of dorsal pharyngeal gland about 2 µm behind stylet knobs. Pharyngeal glands diameter ca 50% of body diameter, extending over intestine, distance from head to end of glands being 9–14% of total body length.

Secretory/excretory pore posterior to pharyngeal gland; with prominent duct; secretory/excretory cell obscure. Hemizonid extending over two or three annules, immediately anterior to secretory/excretory pore.

Testis single, extending to nerve ring; outstretched; slender, with two spermatids per row; testis, seminal vesicle and vas deferens not clearly differentiated. Bursa crenate at anterior end, smooth in tail region; may be prominent or obscure; anterior arising near excretory pore i.e., 60–80% of body length anterior to tail tip. Spicules paired, angled at 35–40% of length, i.e., manubrium and shaft longer than blade; not heavily sclerotised; manubrium offset, wider than shaft; blade narrowing gradually to a bluntly rounded tip with a small notch on proximal edge; opening terminal. Inconspicuous muscles associated with cloaca. Tail conoid, relatively slender, more or less ventrally concave; length 1.7–2.9 times body diameter at cloaca, tip rounded.

Diagnosis and relationships. Fergusobia planchonianae n. sp. is morphologically characterized by the combination of a C-shaped parthenogenetic female with a conoid tail, an arcuate infective female with hemispherical tail tip, and a male almost straight to arcuate in shape with angular spicules, a long peloderan bursa and a narrow tail.

Morphologically, the various stages of Fergusobia planchonianae n. sp. are similar to many other species of Fergusobia . Phylogenetic analyses based on sequences of 28S rDNA D2/D3 ( Fig. 1) suggest that it is closest to an undescribed Fergusobia species collected from stalked unilocular axial pea galls on E.? leucoxylon F. Muell. 1855 (V 70, MSp 21) with 7-bp differences and 1 gap in 852-bp sequenced DNA fragment.

The parthenogenetic female of F. planchonianae n. sp. (open C-shape) differs from F. rileyi (almost straight to arcuate). Fergusobia planchonianae n. sp. is shorter (249–351 µm) than the parthenogenetic female of F. cosmophyllae (354–406 µm), F. magna (418–780 µm), and F. i nd i c a (525–626 µm). The stylet (9–12 µm, mean 11.4 µm) is longer than in F. brevicauda (8–8.5 µm), F. curriei (5–8 µm), F. floribundae (6–7 µm), F. juliae (5–7 µm), F. minimus (4–8 µm), and F. morrisae (7–8 µm). In having large to enormous pharyngeal glands (b’ 1.8–2.6), it is similar to most described species, but differs from F. jambophila , which has smaller glands. In F. planchonianae n. sp., the posterior region of the parthenogenetic female narrows abruptly posterior to the vulva to a rounded tail tip; thus differing from F. pimpamensis , F. pohutukawa , F. ptychocarpae (longer and more slender with a bluntly rounded tip), F. cajuputiae , F. dealbatae , F. fasciculosae , F. leucadendrae , F. nervosae , F. quinquenerviae , and F. viridiflorae (tip more broadly rounded); and F. philippinensis , F. tumifaciens and F. viminalisae n. sp. (body narrows more gradually). In length (11–16 µm, mean 14), the tail of the F. planchoniana n. sp. parthenogenetic female is shorter than in F. brittenae (23–37 µm), F. camaldulensae (17–39 µm) and F. eugenioidae (18–27 µm); and is usually shorter than in F. diversifoliae (15–33 µm, mean 24). It differs from F. colbrani in having a bluntly rather than a broadly rounded tail tip. Morphologically, it is not possible to separate the parthenogenetic female from those of F. planchonianae n. sp. and F. delegatensae , F. f i s he r i, F. microcarpae , and F. porosae .

The infective female of F. planchonianae n. sp. is arcuate and/or with strongly curved posterior region and thus differs in shape from F. brittenae , F. curriei (open C-shape); from F. brevicauda , F. delegatensae , F. diversifoliae , F. eugenioidae , F. juliae , F. leucadendrae , F. quinquenerviae , and F. viridiflorae (arcuate without strongly curved posterior regions); and from F. po ro s ae and F. rileyi (almost straight). In length (303–339 µm), it is shorter than infective females of F. magna (537–633 µm), F. camaldulensae (346–454 µm), F. c o l b r a ni (369–405 um), F. cosmophyllae (374–448 µm), F. floribundae (357–450 µm), F. pimpamensis (369–443 µm), and F. ptychocarpae (387–471 µm). The stylet (5–7 µm) is shorter than in F. dealbatae (8–10 µm). The body behind the vulva is arcuate, with hemispherical tip and thus differs from that in F. morrisae and F. viminalisae n. sp. (more curved); F. cajuputiae , F. fasciculosae , and F. nervosae (with broadly rounded tail tips); and F. philippinensis (truncate tip). Morphologically, the infective female of F. planchonianae n. sp. is similar to that of F. f i s h e r i, F. microcarpae , F. minimus , except that those species lack a post-anal intestinal sac.

The male of F. planchonianae n. sp. is so variable in shape that this character cannot be used to separate it from other species of Fergusobia . Males are shorter (291–373 µm) than those of F. magna (446–558 µm), F. camaldulensae (383–451 µm), F. cosmophyllae (374–502 µm), F. diversifoliae (413–459 µm), F. juliae (377–453 µm), F. pimpamensis (407–525 µm), F. pohutukawa (398–469 µm), F. ptychocarpae (405–535 µm), and F. rileyi (378–508 µm); and mostly shorter than F. minimus (368–502 µm). The ratio a (7.4–10.7) is smaller than in males of F. juliae (11.1–15.3) and F. pohutukawa (12.2–15.5). The stylet of the male of F. planchonianae n. sp. is mostly longer than that of F. minimus (7–10 vs 4–7 µm). Tail shape of the male of F. planchonianae n. sp. (slender, straight to arcuate, bluntly rounded tip) differs from that of F. brevicauda , F. cajuputiae , F. delegatensae , F. eugenioidae , F. floribundae , F. leucadendrae , F. nervosae , and F. quinquenerviae (tips more broadly rounded); and F. philippinensis (truncate tip). Spicules (18–23.5 µm) are longer than in F. viminalisae n. sp. (10–15 µm) and angular, thus differing from F. jambophila , in which they are arcuate. The bursa is long (60–80% of body length, arising posterior to the secretory/excretory pore); thus differing from F. brevicauda , F. brittenae , F. colbrani , F. curriei , F. dealbatae , F. fasciculosae , F. fisheri , F. leucadendrae , F. microcarpae , F. morrisae , F. nervosae , F. porosae , F. quinquenerviae , and F. tumifaciens , in which the bursa is shorter (50% or less); and from F. viridiflorae in which the bursa is longer, arising anterior to the secretory/excretory pore.

Etymology. Named after E. planchoniana , the host plant from which the nematodes were collected.

Figures

FIGURE 4. Fergusobia planchonianae n. sp. from E. planchoniana (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.

Tables

TABLE 3. Measurements (µm) of Fergusobia planchoniana n. sp. from E. planchoniana. (mean ± standard deviation (range )).

	Holotype Parthen-ogenetic female	Parthenogenetic females	Males	Infective females
n		14	20	5
Length	292	301±23 (249–351)	330±29 (291–373)	321±16 (303–339)
a	8.2	7.7±1.1 (5.8–9.6)	9.2±0.9 (7.4–10.7)	9.9±0.3 (9.3–10.0)
b’	2.1	2.1±0.3 (1.8–2.6)	2.8±0.6 (1.9–4.2)	3.2±0.2 (3.0–3.3)
c	20.5	22.1±3.5 (15.6–26.7)	9.5±1.2 (8.4–13.9)	14.1±3.7 (9.4–19.0)
c’	0.8	0.7±0.2 (0.5–1.1)	2.1±0.3 (1.5–2.9)	1.0±0.3 (0.8–1.4)
V%	89.6	85.7±2.1 (83.5–89.6)		80.5±2.7 (76.9–83.2)
T%			71±12.2 (47–87)
Body diameter	36	40±5 (34–52)	36±4 (30–45)	33±2 (30–34)
Stylet length	10	11.4±0.9 (9–12)	8.4±1.1 (7–10)	6.6±0.9 (5–7)
Ant. end to S/E pore	76	83±7 (68–93)	84±13 (65–107)	95±20 (80–128)
Spicule length			20.0±1.8 (18–23.5)
Tail length	14	14±2 (11–16)	35±4 (27–43)	24±6 (18–32)