Fergusobia fasciculosae, 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 : 11-15

Description of Fergusobia fasciculosae n. sp. Davies

( Figs 4 , 7 F, 8G)

Measurements. See Table 3 .

Material examined. The description presented here is based on measurements of 13 parthenogenetic females, 22 males, and 5 infective females from stigma galls on Eucalyptus fasciculosa F. Muell. , associated with an undescribed species of Fergusonina ; from a roadside site on the Strathalbyn to Goolwa road, ca 60 km south of Adelaide, South Australia (35°24.24’S 138°46.09’E), collected by Gary Taylor and Kerrie Davies, 4.viii.2000.

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

Paratypes. Vouchers deposited in the Waite Insect and Nematode Collection ( WINC), the University of Adelaide, Adelaide, South Australia, slides number 004498; and the USDA Nematode Collection, Beltsville MD, USA.

Description. Parthenogenetic female. Body arcuate to C-shaped with ventral side convex; smaller than amphimictic pre-parasitic female and males; tapering gradually behind vulva to form short broadly conoid tail. Cuticle with obscure annules (spacing not measured), weak longitudinal striae apparent when viewed with light microscope; lateral fields not seen.

Cephalic region ~70% diameter of body at anterior end, offset, unstriated, 2.2–2.5 µm long; with rounded outline in lateral view and circum-oral area flat or very slightly raised. Stylet 7–10 µm long, with conus 40–50% of length; basal knobs ~2µm wide at base, rounded.

Orifice of dorsal oesophageal gland ~1 µm posterior to stylet knobs. Anterior fusiform part of digestive tract occupying 60–74% of body diameter, length 2–2.8 times diameter. Lumen of tract broadening behind dorsal oesophageal gland. Oesophageal glands enormous, diameter 63–78% of body diameter, extending over intestine, distance from head to end of glands 53% (33–67%) of total body length.

Secretory/excretory pore 59–77 µm from anterior end, opposite oesophageal gland nucleus, secretory/ excretory cell not seen. Hemizonid extending over two annules, 4–5 annules anterior to secretory/excretory pore.

Reproductive tract variable in length, extending part-way along dorsal oesophageal gland or to nerve ring; reflexed near level of nerve ring or at level of oesophageal gland; oviduct usually with two oocytes per row; uterus containing no eggs (in 10 of 13 specimens examined) or one egg; vulva with protruding lips in some specimens, a depressed slit in others. Tail broad, about as long as anal body diameter, bluntly rounded tip.

Infective pre-parasitic female. Infects mature larva or pupa of Fergusonina sp. Body arcuate to open C-shaped when heat-relaxed; maximum diameter at mid-body length, barely narrowing behind vulva. Cuticle with obscure annules, spacing not measured, longitudinal striae apparent when viewed with light microscope; lateral fields not seen. Some large nuclei present in epidermis behind vulva.

Cephalic region ~75% diameter of body at anterior end; barely offset, 1.5 µm long; circum-oral area flat; stylet slender, ~9 µm long, weakly sclerotised with round basal knobs ~1.5 µm wide; conus 50% of length.

Orifice of dorsal oesophageal gland 1µm posterior to stylet knobs. Anterior fusiform part of digestive tract diameter 47–67% of body diameter, length 2.5–4 times diameter (n = 5). Oesophageal glands diameter 25–41% of body diameter, extending over intestine, distance from head to end of glands on average 32 (28–37)% of total body length.

Secretory/excretory pore opening 54–77 µm behind anterior end, about mid length of oesophageal glands; secretory/excretory cell not seen. Hemizonid extending over two annules, four annules anterior to secretory/ excretory pore.

Uterus extending 50–60% of body length in uninseminated females, packed with sperm in inseminated females, extending into a short pouch posterior to vulva in some specimens; vagina at right angle to body axis; anterior end of reproductive tract at level of nerve ring, hypertrophied in some specimens. Vulval lips flat or slightly raised. Tail broad, curved, dorsally concave, about as long as diameter at anus, tip broadly rounded to almost hemispherical.

Male. Body barely J-shaped when heat-relaxed, tail region more or less curved ventrally. Cuticle with obscure annules ~1.2 µm wide, longitudinal striae seen when viewed with light microscope; lateral fields not seen.

Cephalic region ~75% diameter of body at anterior end, offset, ~2 µm long; circum-oral area flat or slightly raised, with lightly sclerotised framework; stylet 7–10 µm long, with conus 40% of length, stylet knobs rounded, ~2 µm wide.

Anterior fusiform part of digestive tract diameter 50–73% of body diameter, length 2.4–3.7 times diameter. Oesophageal glands diameter 69–79% of body diameter, extending over intestine, distance from head to end of glands on average 28–52% (mean 40%) of total body length. Lumen of intestinal tract broadening posterior to oesophageal glands.

Secretory/excretory pore opens 65–86 µm from anterior end, at level of oesophageal gland nucleus; secretory/ excretory cell ~10 µm long. Hemizonid extending over two annules, four annules anterior to secretory/excretory pore.

Reproductive tract with single testis, variable in length, may extend to distal end of oesophageal gland, overlap it or reach to nerve ring; reflexed at base of gland or nerve ring; testis, seminal vesicle and vas deferens not clearly differentiated. Bursa smooth; prominent or obscure; arising 26 – 44% along length of body from tail tip. Spicules paired, angular near middle, usually slender, moderately sclerotised; manubrium not offset, slightly wider than shaft; blade narrowing gradually, tip curving towards tail, opening terminal or just sub–terminal. Inconspicuous muscles associated with cloaca. Tail ventrally concave, length 1.2–2.4 times diameter at cloaca, tip bluntly rounded.

Diagnosis and relationships. Fergusobia fasciculosae n. sp. is morphologically characterized by the combination of an arcuate parthenogenetic female with a short, broadly conoid tail, an open C-shaped infective female with a hemispherical tail tip, and a J-shaped male with angular spicules and short peloderan bursa.

Morphologically, the parthenogenetic females are similar to those of F. curriei , F. quinquenerviae and F. leucadendrae . Infective females are similar to those of F. fisheri , F. cajuputiae , and F. dealbatae . In general form, males are similar to those of F. brevicauda and F. f is h e r i.

The shape (arcuate to open C) of the parthenogenetic female of F. fasciculosae n. sp. differs from that of F. brittenae , F. i n d i c a, F. morrisae n. sp., and F. ptychocarpae (C-shape); and F. rileyi (almost straight). It is shorter (237–285 µm) than F. m a g n a (418–780 µm), F. camaldulensae (296–372 µm), F. i n d i c a (525–626 µm), and F. juliae n. sp. (292–385 µm). In having large to enormous oesophageal glands (b’ 1.5–3.3), it is similar to most described species, but lacks a reflex or extra lobe at the distal end of the gland, as found in F. quinquenervia and F. viridiflorae . The shape of the body posterior to the vulva (arcuate, conoid, with broadly rounded tip) differs from that of F. dealbatae and F. philippinensis (more slender); F. pohutukawa (straight, conoid, with narrowly rounded tip, sometimes with mucron); and F. c u r r i e i (conoid, bluntly rounded tail tip). Length of the tail of parthenogenetic females of F. fasciculosae n. sp. (13–18 µm) is shorter than in F. nervosae (20–30 µm). The ratio c (13.4–20.9) is greater than in F. tumifaciens (10–11); and c’ (0.8–1.3) is less than in F. eugenioidae n. sp. (1.5–2.8). Fergusobia fasciculosae n. sp. lacks the strongly peaked circum-oral area of the cephalic region present in F. jambophila . The hemizonid is further anterior to the secretory/excretory pore in F. cajuputiae (11–12 annules) than in F. fasciculosae n. sp. (4–5 annules). Parthenogenetic females of F. fasciculosae n. sp. are similar to those of F. leucadendrae , but the latter has a smaller oesophageal gland, the distance from head to base of glands being 39–60% of total body length in F. leucadendrae and 63–78% in F. fasciculosae n. sp. F. fasciculosae n. sp is also similar in size and shape to F. fisheri , but lacks the wrinkled cuticle on the posterior ventral side of the body, and the hemizonid is closer to the secretory/excretory pore (4–5 vs 7–8 annules anterior). In having a non-extensile uterus, it differs from F. brevicauda , in which the uterus is extensile.

Infective females of F. fasciculosae n. sp. are morphologically similar to those Fergusobia spp. from broadleaved Melaleuca spp. and to F. f i s h e r i. The infective female (arcuate to open C-shaped) of F. fasciculosae n. sp. differs in shape from F. juliae n. sp., F. morrisae n. sp., F. eugenioidae n. sp., and F ptychocarpae (more curved in posterior region); and F. rileyi (almost straight to arcuate). Infective females of F. fasciculosae n. sp. are shorter (268–332 µm) than those of F. m a gn a (537–633 µm), F. brittenae (375–550 µm), F. camaldulensae (346–454 µm), F. curriei (417–489 µm), F. juliae n. sp. (396–550 µm), F. ptychocarpae (387–471 µm), and F. r i l e y i (378–432 µm); are generally shorter than those F. brevicauda (330–410 µm); and are larger than F. c a j u p u t i a e (239–309 µm), F. nervosae (282 µm), F. quinquenerviae (259–325 µm), and F. viridiflorae (321 µm). The shape of the body behind the vulva (just arcuate, cylindroid, with a broadly rounded to hemispherical tip) differs from that of F. philippinensis (with a broader, sub-truncate tip). Fergusobia fisheri has a generally longer tail than F. fasciculosa e n. sp. (21–49 µm vs 13–25 µm). Ratio c (12.1–21.4) is larger than in F. leucadendrae (9.1–11.7) and ratio c’ (0.7–1.4) is smaller than in F. leucadendrae (1.5–1.6). The females of F. fasciculosae n. sp. are generally shorter than those of F. dealbatae (268–332 µm, mean 290 µm; vs 307–347 µm, mean 324 µm); and have a smaller ratio c’ (0.7–1.4 vs 1.3–1.7), i.e., a broader tail.

In being J-shaped, males of F. fasciculosae n. sp. are similar to males of F. brittenae , F. curriei , F. juliae n. sp., and F. ptychocarpae . F. fasciculosae n. sp. males (274–336 µm) are shorter than those of F. magna (446–588 µm), F. brittenae (339–519 µm), F. camaldulensae (383–451 µm), F. curriei (370–492 µm), F. juliae n. sp. (377–453 µm), F. ptychocarpae (405–535 µm), F. pohutukawa (398–469 µm), and F. rileyi (378–508 µm). The ratio a (9.9–13.9) is greater than that of F. tumifaciens (8–9); but overlaps that of the other described species of Fergusobia . Males of F. fasciculosae n. sp. have a smaller oesophageal gland than those of F. quinquenerviae , in which they are also reflexed at the distal end. Tail shape (arcuate, tip broadly rounded) differs from that of F. jambophila and F. viridiflorae (more slender); and F. philippinensis (truncate tip). The spicule (15–19 µm) is shorter than in F. brevicauda (21–27 µm) and F. eugenioidae n. sp. (23–25 µm). The spicule is not as heavily sclerotised as in F. dealbatae , F. leucadendrae , and F. nervosae . Spicules of F. fisheri have a relatively larger, more offset manubrium than those of F. fasciculosae n. sp. In having a short bursa, males of F. fasciculosae n. sp. differ from those of F. cajuputiae , F. jambophila , and F. morrisae n. sp. (with long bursa).

The status of F. fasciculosae n. sp. as a new species is supported by its sequence divergence in phylogenetic analyses based on sequences of D2/D3 and COI ( Figs 1 , 2 ). From phylogenetic analyses based on sequences of D2/ D3 and COI, F. fasciculosae n. sp. is genetically similar to Fergusobia spp. from pea galls on E. gomphocephala (voucher 63, MSp 9) and Eucalyptus sp. (voucher 32, MSp 28), from FBG on E. microcarpa (voucher 1, MSp 22) and E. fibrosa ( F. morrisae n. sp.), and also groups with F. juliae n. sp. The blast search of the 851-bp sequenced from D2/D3 revealed the highest similarity to vouchers 32, 63 and 68 (MSp17) with 99% match, 12 bp differences and 3 – 4 gaps. The blast search of the 618 bp sequenced COI revealed the highest similarity to vouchers 1, 63, 69 (MSp 36), and 350 ( F. juliae n. sp.) with 94% match, 35 – 39 bp differences and no gap.

Etymology. Named for E. fasciculosa , the host plant from which the nematodes were collected.

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 4. Fergusobia fasciculosae 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 3. Measurements (µm) of Fergusobia fasciculosae n. sp. from E. fasciculosa (mean ± S. D. (range )).

	Holotype Parthenogenetic females	Males	Infective females
n	1 13	22	5
Length	239 254±15.2 (237–285)	310±18.2 (274–336)	290±27.7 (268–332)
a	7.9 8.7±0.8 (7.3–10.0)	11.6±0.9 (9.9–13.9)	10.6±1.1 (8.8–11.6)
b’	1.7 1.9±0.5 (1.5–3.3)	2.5±0.5 (1.9–3.5)	3.1±0.4 (2.7–3.5)
c	13.4 17.0±2.3 (13.4–20.9)	11.4±1.4 (8.7–13.3)	15.4±3.7 (12.1–21.4)
c’	1.1 1.0±0.1 (0.8–1.3)	1.7±0.3 (1.2–2.4)	1.1±0.3 (0.7–1.4)
V %	86.6 84.6±1.4 (82.6–86.6)		81.4±1.5 (79.5–83.3)
T %		64.0±13.0 (46.5–81.9)
Body diameter	30 30±2.3 (25–32)	27±1.5 (24–30)	28±2.0 (25–30)
Stylet length	9 8.8±1.0 (7–10)	8.1±0.8 (7–10)	9
Ant. end to SE pore	68 65±4.8 (59–77)	76±4.9 (65–86)	67±9.7 (54–77)
Spicule length		17.1±1.2 (15–19)
Tail length	18 15±1.9 (13–18)	28±3.9 (22–36)	20±4.7 (13–25)