Fergusobia porosae, 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. IV. Fergusobia from flat leaf galls on Eucalyptus and Corymbia, with descriptions of two new species, Zootaxa 3741 (1), pp. 151-171 : 160-164

Fergusobia porosae n. sp. Davies

( Figs 4 , 5 D, 6C)

Measurements. Table 3 .

Material examined. Holotype, parthenogenetic ♀, Strathalbyn to Goolwa road, ~ 60 km south of Adelaide, SA (35°24´S 138°46´E). From flat leaf galls on Eucalyptus porosa F. Muell. ex Miq. growing in roadside vegetation, collected by Gary Taylor, 4.viii.2000, on a slide with a paratype ♂ and infective ♀, deposited at the ANIC, Canberra, ACT, Australia.

Paratypes, WINC, slide numbers 0 0 4270, 0 0 4510, 0 0 4793, from flat leaf galls with Fergusonina sp. on E. porosa at two sites in South Australia: roadside vegetation on Strathalbyn to Goolwa road, 35°24´S 138°46´E, coll. Gary Taylor, 4.viii.2000 (WNC 2086, 2094); and from roadside vegetation 6.6 km south-west of Wool Bay, 35°01´S 137°41´E, coll. Gary Taylor, 9.xi. 2003 (WNC 2340). Thirty one parthenogenetic ♀♀, 5 pre-parasitic infective ♀♀, 31 ♂♂, and various juveniles.

Description. Parthenogenetic female. From flat leaf galls on E. porosa . Body an open C to C-shape when heat relaxed, dorsally curved with ventral side convex; similar in size to both amphimictic pre-parasitic females and males; body narrowing sharply posterior to vulva to form a small tail. Cuticular annulations obscure, spacing not measured; longitudinal striae obvious when viewed with light microscope; lateral fields not seen.

Cephalic region diameter ~70–80% of body diameter immediately posterior, offset, 1–1.5 µm long, unstriated; rounded in lateral view, circum-oral area flat or slightly raised. Stylet with conus 40–50% of total length, basal knobs well defined, 2–3 µm across, round.

Orifice of dorsal oesophageal gland 1–2 µm posterior to stylet knobs. Anterior fusiform part of digestive tract occupying 69% (61–77%) of body diameter, length 1.7–2.4 times diameter; lumen of tract broadening at ~50% length of dorsal oesophageal gland. Oesophageal glands large to enormous, occupying ~70–80% of body diameter, extending 30–59% (mean 48%) of total body length.

Secretory/excretory pore with short duct leading to ellipsoid secretory/excretory cell ~10 µm long. Hemizonid 2 annules long, positioned 2 to 4 annules in anterior to secretory/excretory pore.

Reproductive tract variable in length, extending part-way along dorsal oesophageal gland, to nerve ring or to base of stylet knobs; outstretched or with one flexure (posterior to gland or posterior to nerve ring); oviduct with two oocytes per row; uterus mostly containing no eggs (one egg in 4 of 21 specimens); vulva mostly a depressed slit (in 14 of 21 specimens), occasionally with protruding lips (in 5 of 21 specimens), rarely flat (in 2 of 21 specimens). Anus opening into a small depression in the cuticle. Tail short, conoid, with small volume; length 1– 1.8 times anal body diameter, tip rounded.

Infective pre-parasitic female. From flat leaf gall on E. porosa . Infecting mature larval stage or pupa of Fergusonina sp. Body arcuate or almost straight when relaxed by heat; maximum body diameter at mid-body length; diameter declining gradually in tail region. Cuticular annulation obscure, weak longitudinal striae apparent when viewed with light microscope; lateral fields not seen.

Cephalic region diameter 70–75% of anterior body diameter, barely offset; circum-oral area flat or slightly raised; stylet slender, weakly sclerotised with small round basal knobs ~2 µm across; conus 40% of total length.

Orifice of dorsal oesophageal gland 2 µm posterior to stylet knobs. Anterior fusiform part of digestive tract occupying 59–68% of body diameter, length 2.2 (2.0–2.6) times diameter. Oesophageal glands occupying 40–50% body diameter, extending over intestine to average 27% (25–30%) body length.

Secretory/excretory pore opening posterior to level of oesophageal gland nucleus; secretory/excretory cell not seen. Hemizonid positioned 2 or 3 annules anterior to secretory/excretory pore.

Uterus packed with sperm in inseminated females; vagina perpendicular to body axis; reproductive tract extending to nerve ring, sometimes hypertrophied. Vulval lips flat or barely protruding (by about 1 µm). Tail short, broad; length 0.7–1.2 times diameter at anus; tip almost hemispherical.

Male. From flat leaf galls on E. porosa . Body almost straight to arcuate to barely J-shaped when relaxed by heat, tail region arcuate dorsally concave. Cuticle with obscure annules spacing about 1.5 µm apart, longitudinal striae obvious when viewed with light microscope; lateral fields not seen.

Cephalic region occupying 70–80% of anterior body diameter, ~1–2 µm long; circum-oral area flat or slightly raised, with lightly sclerotised framework; stylet with conus ~50% of total length, stylet knobs round, ~2 µm across.

Orifice of dorsal oesophageal gland 1–2 µm posterior to stylet knobs. Anterior fusiform part of digestive tract occupying 67–83% of body diameter, length 2.2 (1.8–2.5) times diameter. Oesophageal glands occupying ~50– 80% of body diameter, extending over intestine to average 30–48% (mean 43%) of total body length.

Secretory/excretory pore opens at ~50% of length of oesophageal gland; duct obscure; secretory/excretory cell not seen. Hemizonid extending over 2 annules, usually positioned 4–5 annules anterior to secretory/excretory pore.

Reproductive tract with single testis, variable in length, usually overlapping dorsal oesophageal gland but may extend to nerve ring; reflexed or outstretched; testis, seminal vesicle and vas deferens not clearly differentiated. Bursa smooth, peloderan, prominent or obscure, arising 15 – 33% along length of body from tail tip. Spicules paired, angled at ~40% of their length (i.e., manubrium and shaft longer than blade), not heavily sclerotised; manubrium sometimes wider than shaft, sometimes offset; blade narrowing gradually to rounded tip; opening sub–terminal. Muscles associated with cloaca inconspicuous. Tail arcuate, ventrally concave; length 1.5–2.5 times diameter at cloaca; tip bluntly rounded.

Diagnosis and relationships. Fergusobia porosae n. sp. is morphologically characterized by the combination of an arcuate to C-shaped parthenogenetic female with a small conoid tail, an almost straight to arcuate infective female with an hemispherical tail tip, and males that are almost straight to barely J-shaped with angular spicules and short peloderan bursa.

Morphologically, F. porosae n. sp. is similar to F. microcarpae n. sp. and F. fisheri. From phylogenetic analyses based on sequences of D 2 /D3 and COI, it is genetically close to Fergusobia spp. collected from flat leaf galls on E. siderophloia (V’s 25–28), Eucalyptus spp. (V’s 29, 348), E. microcarpa (V 67), and F. f i s h e r i from E. leucoxylon It is also close to F. eugenioidae from flower bud galls on E. eugenioides (V 349), and Fergusobia spp. from axial bud galls on E. porosa (V 69).

The arcuate to open C-shaped parthenogenetic females of F. porosae n. sp. are similar to those of F. jambophila and F. fisheri , but different to those of F. brittenae , F. i n d i c a, F. microcarpae n. sp., and F. ptychocarpae (more curved); and from F. leucadendra and F. r i l ey i (almost straight to arcuate). In length (265–357 µm), F. porosae n. sp. is smaller than F. magna (418–780 µm) and F. tumifaciens (415 µm); and larger than F. cajuputiae (221–273 µm) and F. fasciculosae (237–285 µm). The stylet (9–9.5 µm) of parthenogenetic females of F. p o ro s a e n. sp. is shorter than in F. camaldulensae (11–13 µm), and longer than in F. brevicauda (8–8.5 µm), F. curriei (5–8 µm), F. juliae (5–7 µm), and F. morrisae (7–8 µm). In having large to enormous oesophageal glands (b’ 1.7–3.3), it is similar to most described species, but differs from F. jambophila which has smaller glands and from F. quinquenerviae which has enormous glands with a reflex or extra lobe at the posterior end. The shape of the body behind the vulva (arcuate, with a small volume and a bluntly rounded tip) differs from that in F. philippinensis (ventral edge from vulva to tail tip less curved); and F. pohutukawa (narrow, conoid tip). The length of the tail separates F. p o ro s a e n. sp. (9–20µm) and F. eugenioidae (18–27 µm). The hemizonid is 2–4 annules anterior to the secretory/excretory pore in F. p o ro s a e n. sp., but immediately anterior in F. eugenioidae , and 7–8 annules anterior in F. fisheri . In parthenogenetic females of F. p o ro s a e n. sp., the anus opens into a depression in the cuticle which is not seen in F. dealbatae or F. nervosa .

Infective females of F. p o ro s a e n. sp. are almost straight to arcuate in shape, which is different to F. magna , F. brittenae , F. curriei , F. fasciculosae , F. microcarpae n. sp. (which are arcuate to open C- shape); F. eugenioidae , F. juliae , F. morrisae , and F ptychocarpae (which are strongly curved in posterior region); and F. r i l e y i (which are almost straight). Fergusobia porosae n. sp. infective females are shorter (277–300 µm) than those of F. magna (537–633 µm), F. brevicauda (330–410 µm), F. brittenae (375–550 µm), F. curriei (417–489 µm), F. dealbatae (307–347 µm), F. eugenioidae (438 µm), F. juliae (396–550 µm), F. morrisae (322–395 µm), F. ptychocarpae (387–471 µm), and F. r i l e y i (378–432 µm). The shape of the body behind the vulva (straight, with almost hemispherical tip), differs from F. nervosae and F. viridiflorae (more curved, with bluntly rounded tail tips), F. camaldulensae (arcuate with hemispherical tip), and F. philippinensis (truncate tip). In F. porosae n. sp., the ratio c (15.3–23.4) is larger than in F. leucadendrae (9.1–11.7). Infective females of F. p o ro s a e n. sp. are morphologically similar to those of F. fisheri , but are mostly straighter and with a more narrowly rounded tail tip. They are also similar to F. quinquenervia and F. cajuputiae , but mostly have smaller oesophageal glands (b’ 3.3–4 vs 2.2–3.2 and 2.2–3.1). In addition, F. p o ro s a e n. sp. differs from F. quinquenerviae in having a shorter tail (13–20 µm vs 20–29 µm) and a larger ratio c (15–23 vs 11–15).

The shape of males of F. porosae n. sp. (almost straight to arcuate to barely J-shape) is similar to that of many species of Fergusobia . Male F. p o ro s a e (270–326 µm long), are shorter than male F. magna (446–588 µm), F. brevicauda (330–420 µm), F. camaldulensae (383–451), F. curriei (370–492 µm), F. eugenioidae (341–420 µm), F. morrisae (347–413 µm), F. pohutukawa (398–469 µm), F. ptychocarpae (495–525 µm), F. rileyi (378–508 µm), and F. tumifaciens (415 µm). Tail shape (arcuate with bluntly rounded tip) differs from that of F. philippinensis (truncate). The c ratio (7.9–12.6) is smaller than in F. quinquenerviae (12.9–17.8). Spicule length (11–15.5 µm) is smaller than in F. brittenae (19–25 µm), F. dealbatae (18–22 µm), F. fisheri (16–20 µm), F. juliae (20–27 µm), F. nervosae (16–19 µm), and F. viridiflorae (18–20 µm). The bursa of F. p o ro s a e n. sp. is short and differs from that of F. cajuputiae and F. jambophila (in which it is longer). Males of F. p o ro s a e n. sp. have more lightly sclerotised spicules than do those of F. leucadendrae . Males of F. p o ro s a e n. sp. have heavier-looking spicules than F. fasciculosae , but the tail has a slimmer shape.

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

Figures

FIGURE 4. Fergusobia porosae n. sp. (all in lateral view): A, Entire parthenogenetic female; B, Head of parthenogenetic female; C, Habitus of parthenogenetic female; D, Tails of parthenogenetic females; E, Entire infective female; F, Head of infective female; G; Habitus of infective female; H, Tails of infective females; I, Entire male; J, Head of male; K, Habitus of males; L, Tails of males. Scale bars: A, E, I = 50 Μm. B, F, J = 5 Μm. C, D, G, H, K, L not drawn to scale.

FIGURE 5. Habitus drawings of Fergusobia spp. (most undescribed) collected from flat leaf galls: A, from E. albens; B, F. microcarpae n. sp. from E. microcarpa; C, from E. odorata; D, F. po ros a e sp. nov from E. porosa; E, F. fisheri from E. leucoxylon; F, from E. siderophloia; G, from C. intermedia; H, from Eucalyptus sp. from Brisbane; I, from Eucalyptus sp. from Lake Tinnaroo. Scale bars = 50 Μm.

Tables

TABLE 3. Measurements (µm) of Fergusobia porosae n. sp. from flat leaf galls on E. porosa (mean ± standard deviation (range )).

	Holotype, Parthenogenetic female	Parthenogenetic females	Males Infective females
n Length a b’ c c’	292 8.6 1.7 20.4 1.6	21 294±21.2 (265–357) 8.6 ±0.8 (7.6–10.2) 2.1 ±0.4 (1.7–3.3) 19.5± 4.5 (8.9–20.4) 1.4 ±0.3 (0.9–1.8)	22 5 302±16.0 (270–326) 292±8.8 (277–300) 9.5±0.9 (8.3–11.1) 10.9±0.7 (10.3–12.0) 2.3±0.3 (2.1–3.3) 3.8± 0.3 (3.3–4.0) 10.1±1.1 (7.9–12.6) 18.2± 3.3 (15.3–23.4) 1.7±0.2 (1.4–2.3) 0.9 ±0.2 (0.7–1.2)
V% T% Body diameter	89.6 34	86.9±1.3 (84.3–89.6) 34±2.2 (30–37)	85.4±0.4 (84.8–85.8) 71.7±5.3 (60.2–78.4) 32±2.9 (28–37) 27±1.3 (25–29)
Stylet length Ant. end to SE pore Spicule length	9 93	9±0.3 (9–9.5) 82±11.6 (52–104)	8±0.7 (7–9.5) 9.0±0.7 (8–10) 86±8.0 (74–102) 57 13±1.2 (11–15.5)
Tail length	14	16±3.8 (9–20)	30±3.5(26–39) 16±2.6 (13–20)