Fergusobia tolgaensis Davies

Davies, Kerrie A., Ye, Weimin, Giblin-Davis, Robin M., Taylor, Gary S., Purcell, Matthew & Thomas, Kelley, 2014, Nematodes from galls on Myrtaceae. IX. Fergusobia rosettae n. sp. on Melaleuca quinquenervia and F. tolgaensis n. sp. on Syzygium luehmannii, from Queensland, Zootaxa 3889 (2), pp. 214-236: 221-226

publication ID

http://dx.doi.org/10.11646/zootaxa.3889.2.3

publication LSID

lsid:zoobank.org:pub:BBBE41C7-C8F1-476D-B136-80D11743F43D

DOI

http://doi.org/10.5281/zenodo.5612488

persistent identifier

http://treatment.plazi.org/id/1136879A-8767-9431-FF77-B6ACBB6EFE56

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Plazi

scientific name

Fergusobia tolgaensis Davies
status

 

Description of Fergusobia tolgaensis Davies   n. sp.

( Figs 2 View FIGURE 2 , 3 View FIGURE 3 B, 4 B)

= Fergusobia   MSp 31 apud Davies et al., 2012 a

Measurements. Table 3 View TABLE 3 .

Holotype partheno- Parthenogenetic females Males Infective females

genetic female

Material examined. Holotype, parthenogenetic ♀, from a bush planted in a garden at Tolga Woodworks, Tolga, Atherton Tableland, QLD (17 º 19 ’S, 145 º 50 ’ E). From unilocular leaf, stem and flower bud galls on Syzygium luehmannii (F.Muell.) L.A.S. Johnson 1962   , collected by KA Davies 16.vii. 2005. On slide with a paratype ♂ and an infective ♀, deposited at the ANIC, Canberra, ACT, Australia.

Paratypes, WINC, The University of Adelaide, SA, Australia, 5 parthenogenetic ♀s, 1 pre-parasitic infective ♀s, 5 ♂ s, slide numbers WNC 2462; Queensland Museum, Brisbane, QLD, Australia, 13 parthenogenetic ♀s, 1 pre-parasitic infective ♀s, 10 ♂ s; and at the USDA Nematode Collection, Beltsville, MD, USA 1 parthenogenetic ♀, 1 pre-parasitic infective ♀ and 1 ♂. Twenty parthenogenetic ♀♀, 4 pre-parasitic infective ♀♀, and 17 ♂♂.

Description. Parthenogenetic female. Body shape arcuate when heat-relaxed; relatively small (<350 µm); relatively broad (a 7–11); similar in size to amphimictic pre-parasitic females and to males; body narrows behind vulva to form conoid tail. With light microscope, cuticle appears smooth, longitudinal striae in sub-cuticle not apparent. Lateral fields not seen.

Cephalic region ~ 75 % diameter of body at anterior end, off–set, 2 µm high, unstriated; rounded outline in lateral view, circum-oral area raised ~ 1 µm. Stylet with cone 30–40 % length, tiny basal knobs just higher than wide, ~ 1 µm wide at base, rounded.

Orifice of dorsal pharyngeal gland ~ 1–2 µm posterior to stylet knobs. Anterior fusiform part of digestive tract diameter 52–70 % (mean 64 %) of body diameter, length 1.9–3.6 times diameter. Lumen of tract broadens at distal end of dorsal pharyngeal gland. Pharyngeal glands extending over intestine, large, diameter 35–78 % (mean 62 %) of body diameter, distance from head to end of glands being 11–30 % (mean 18 %) of total body length.

Secretory/excretory pore with obscure duct, opens opposite nucleus of pharyngeal gland; secretory/excretory cell not seen. Hemizonid extending over two annules, 0 to 4 or 5 annules anterior to secretory/excretory pore.

Reproductive tract variable in length, extending to secretory/excretory pore, part-way along pharyngeal gland or to nerve ring; flexed in 1 / 15 specimens examined; oviduct usually with oocytes in a single column; quadricolumella not smooth, uterus long, extensile; with no eggs in 5 specimens, 1 in 2, 2 in 4, 3 in 1, 4 in 5 and 5 in 1 specimen; vulva a simple transverse slit with barely or distinctly protruding rounded lips; no vulval plate. Anus pore-like. Tail short, conoid, may be slightly concave on ventral side; length 1.5–2 times anal body diameter; broadly rounded tip.

Infective pre-parasitic female. Infects mature larval stage of Fergusonina   sp. or pupa. Arcuate shape when relaxed by heat; relatively broad (a 8–12); maximum body diameter at mid-body length; body tapers gradually behind vulva. Cuticle obscurely annulated, longitudinal striae of sub-cuticle not apparent with light microscope; lateral fields not seen.

Cephalic region just offset, domed shape; circum-oral area rounded, slightly raised; stylet slender, 7 µm long, weakly sclerotised with retrorse basal knobs higher than wide; ~ 1 µm wide; cone ~ 40 – 50 % of length.

Orifice of dorsal pharyngeal gland often obscure, ~ 1 µm posterior to stylet knobs. Anterior fusiform part of digestive tract little expanded, diameter 48–64 % of body diameter, length 2.5–3.8 times diameter. Pharyngeal glands extending over intestine, diameter ~ 30 % of body diameter, distance from head to end of glands being 25–50 % (mean 40 %) of total body length.

Secretory/excretory pore opens 71–81 µm from anterior end, behind pharyngeal glands; duct obscure; secretory/excretory cell not seen. Hemizonid not seen.

Uterus ~ 70 % of total gonad length in uninseminated females, packed with sperm in inseminated females; vagina anteriorly directed; reproductive tract extending to nerve ring; tract hypertrophied in length in some specimens. Vulva a transverse slit, vulval lips raised ~ 1 µm, no vulval plate present. Anus an obscure pore. Tail sub-cylindroid; relatively short (c = 10–12); length 2 times diameter at anus; tip broadly rounded.

Male. Body arcuate when relaxed by heat, tail region slightly curved ventrally. Cuticle obscurely annulated, longitudinal striae of sub-cuticle not apparent with light microscope; lateral fields not seen.

Cephalic region occupying ~ 70–90 % anterior body diameter, offset, ~ 1.5 µm high; circum-oral area raised, with lightly sclerotised framework; stylet with cone 40–50 % of length, round stylet knobs 2–3 µm wide.

Anterior fusiform part of digestive tract diameter 53–82 % of body diameter, length 1.9–3.1 times diameter. Orifice of dorsal pharyngeal gland 2–3 µm behind knobs. Pharyngeal glands extending over intestine, diameter 70 (50–80)% of body diameter, distance from head to end of glands being 33–50 % (mean 37 %) of total body length.

Secretory/excretory pore opens anterior to level of nucleus of pharyngeal gland; duct obscure; secretory/ excretory cell not seen. Hemizonid lens-like, extending over two annules, immediately in front of secretory/ excretory pore.

Reproductive tract with single testis, variable in length, may extend to nerve ring but usually overlaps dorsal pharyngeal gland; may be reflexed; testis, seminal vesicle and vas deferens not clearly differentiated. Bursa apparently leptoderan, smooth; may be prominent or obscure; arises 33 – 55 % along length of body from tail tip. Spicules paired, angular at about 40 % of length, with manubrium and shaft longer than blade; moderately sclerotised; manubrium wider than shaft, not offset; blade narrows gradually to bluntly rounded tip with concavity on distal edge; opening sub-terminal. Inconspicuous muscles associated with cloaca. Tail arcuate, ventrally concave, conoid; length 1.5–2.5 times diameter at cloaca; broadly rounded tip.

Diagnosis and relationships. Fergusobia tolgaensis   n. sp. is morphologically characterized by the combination of a small open C-shaped parthenogenetic female with a broadly conoid tail, an arcuate infective female with a broadly rounded tail tip, and an arcuate male with an angular (not heavily sclerotised) spicule and short to mid-length leptoderan bursa.

Morphologically, Fergusobia tolgaensis   n. sp. is similar to F. leucoxylonae   , F. microcarpae   , F. p oro s a, and F. sporangae   . From phylogenetic analyses based on sequences of D 2 /D 3, large sequence divergences support F. tolgaensis   n. sp. as a unique species. It is genetically close to undescribed Fergusobia   spp. from unilocular pea galls on E. tereticornis   and Eucalyptus   sp. (Davies et al. 2010 a).

The parthenogenetic female of F. tolgaensis   n. sp. (open C-shape) differs from F. cosmophyllae   , F. floribundae   , F. indica   , F. magna   , F. minimus   , and F. morrisae   (C-shape); from F. fasciculosae   (arcuate); and from F. rileyi   (almost straight to arcuate). The stylet (7–9 µm) of this parthenogenetic female is longer than in F. curriei   (5–8 µm), F. juliae   (5–7 µm), and F. morrisae   (7–8 µm); and shorter than in F. camaldulensae   (11–13 µm). In having a large to enormous pharyngeal gland (b’ 2–4), it differs from F. jambophila   , which has smaller glands, and from F. quinquenerviae   which has larger glands with an extra lobe or flex. In F. tolgaensis   n. sp., the vulva (86–92 %) is more posterior than in F. jambophila   (81–85 %), F. nervosae   (81–83 %), and F. pimpamensis   (76–85 %). In having a body behind the vulva that narrows gradually, is arcuate and conoid in shape, with a bluntly rounded tip, this female differs from F. fasciculosae   , F. brevicauda   , F. cajuputiae   , F. leucadendrae   , and F. viridiflorae   (with broadly rounded tips); from F. pohutukawa   (straight, conoid); from F. brittenae   , F. dealbatae   , F. delegatensae   , F. eugenioidae   , F. leucoxylonae   , F. philippinensis   , and F. ptychocarpae   (more slender, arcuate to straight); and from F. diversifoliae   , F. gomphocephalae   and F. planchonianae   (bodies narrow rapidly behind the vulva). The parthenogenetic female of F. tolgaensis   n. sp. is similar to F. fisheri   but can be separated from it on the position of the hemizonid (respectively, 0–4 or 5 vs 7–8 annules in front of the excretory/secretory pore). It lacks the broad opening of the stylet aperture present in F. sporangae   . In having cephalic regions with a distinctly raised circum-oral area, the female of F. tolgaensis   n. sp. is separated from that of F. colbrani   , F. microcarpae   and F. viminalisae   in which it is flat or flatter. It is separated from F. porosae   only by tending to have a broader base to the conoid tail, giving it an apparently larger volume than in the latter. It tends to have a smaller stylet, which is less sclerotised, than in F. tumifaciens   (respectively, 7–9 vs 8.5–10 µm). In length (mean 22 µm, range 18–25 µm) the tail of the F. tolgaensis   n. sp. parthenogenetic female is usually longer than in F. ro s et t a e n. sp. (9–21 µm, mean 14 µm). It is difficult to separate F. tolgaensis   n. sp. from F. schmidti   , but the former tend to be slimmer (respectively, ratio a 9.0(7.0–11.0) vs 6.2 (5.2–9.1 )).

The infective female of F. tolgaensis   n. sp. (arcuate) differs in shape from F. brittenae   (open C-shape); from F. viminalisae   (strongly curved in posterior region), and from F. r i l e yi (almost straight). In length (223–272 µm), it is smaller than the infective female of F. c o l b r an i (369–405 µm), F. magna   (537–633 µm), F. minimus   (419–458 µm), and F. tumifaciens   (354–445 µm). The a ratio (8.0– 11.9, mean 10.4) is larger than in F. cosmophyllae   (4.0– 6.8). The stylet of F. tolgaensis   n. sp. is smaller than that of F. quinquenerviae   (respectively, 7 vs 9–10 µm long). The infective female can be separated from that of F. eugenioidae   by having a flat, rather than a raised, circum-oral area. It has a broader anterior fusiform part of the pharynx than F. juliae   (respectively, occupying 50–76 % vs 13–28 % of body diameter). The pharyngeal gland in F. tolgaensis   n. sp. is larger than those in F. morrisae   (respectively, b’ ratio 2.0–3.0 vs 4.4–6.9). It lacks the post-anal intestinal sac that is present in F. planchonianae   . The infective females of F. camaldulensae   , F. curriei   , F. dealbatae   , F. delegatensae   , F. diversifolia   , F. fasciculosae   , F. fisheri   , F. floribundae   , F. gomphocephalae   , F. leucadendrae   , F. leucoxylonae   , F. microcarpae   , F. po ro s ae, F. rosettae   n. sp. and F. sporangae   have broad tails with a near hemispherical tip, separating them from F. tolgaensis   n. sp., which has a more slender tail with a bluntly rounded tip, and from F. philippinensis   , with a tip that is truncate in shape. The infective female of F. tolgaensis   n. sp. has a larger c’ ratio (1.6–2.2, mean 1.9) than in F. cajuputiae   , F. schmidti   and F. ptychocarpae   (respectively, 0.8–1.8 (mean 1.3), 0.5–1.4 (mean 0.8), and 0.6–0.9 (mean 0.8 )). The infective female of F. pimpamensis   tends to have a c ’ ratio smaller than that of F. tolgaensis   n. sp. (respectively, 0.4–1.3, mean 0.8 vs 1.6–2.2, mean 1.9), i.e., has a tail that is longer relative to diameter. Again, it is difficult to morphologically separate the infective female of F. tolgaensis   n. sp. and F. viridiflorae   , but the former tends to have stronger curvature of the tail region and greater body length (respectively 334–437 µm vs 307–347 µm). While no specimens of F. brevicauda   have been examined, it appears from Siddiqi’s description that the infective female of that species has a broader tail and a larger c ratio than occurs in F. tolgaensis   n. sp. (respectively, 12–15 vs 10–12). It is not possible to morphologically separate the one infective female of F. nervosae   that has been examined from those of F. tolgaensis   n. sp.

In shape (almost straight to arcuate or open C-shaped), the male of F. tolgaensis   n. sp. differs from F. schmidti   and F. planchonianae   (in which the posterior region is strongly curved). In length (268–349 µm), it is smaller than those of F. camaldulensae   (383–451 µm), F. cosmophyllae   (374–502 µm), F. curriei   (370–492 µm), F. diversifoliae   (413–459 µm), F. floribundae   (403–570 µm), F. juliae   (377–453 µm), F. magna   (446–588 µm), F. minimus   (368–502 µm), F. pimpamensis   (407–525 µm), F. pohutukawa   (398–469 µm), F. ptychocarpae   (405–535 µm), and F. rileyi   (378–508 µm). In length (7–10 µm), the stylet is shorter than in F. leucoxylonae   (10–13 µm). The shape of the tail (arcuate with a broadly rounded tip) differs from that of F. philippinensis   (truncate tip); from F. leucadendrae   (bluntly rounded tip); and from F. viridiflorae   (slender, straight to arcuate). Spicule length (14–18 µm) is shorter than in F. brevicauda   (21–27 µm), F. brittenae   (19–25 µm), and F. eugenioidae   (23–25 µm), and tends to be shorter than in F. dealbatae   (18–22 µm), F. morrisae   (18–23 µm), F. sporangae   (17–25 µm), and F. tumifaciens   (18–22 µm). In having an angular spicule, F. tolgaensis   n. sp. differs from F. jambophila   and F. pimpamensis   , in which it is arcuate. The bursa is short to mid-length (33–55 % of body length measured from the tail tip) differing from F. minimus   and F. tumifaciens   (in which it arises at 12–28 % and 9–16 % of body length); and reaches the tail, differing from F. delegatensae   in which it ends just posterior to the cloaca. In having a cephalic region with a distinctly raised circum-oral area, the male of F. tolgaensis   n. sp. differs from those of F. cajuputiae   , F. fasciculosae   , F. fisheri   , F. gomphocephalae   , F. leucadendrae   , F. microcarpae   , F. quinquenerviae   , and F. viminalisae   in which it is flat or barely raised. The position of the hemizonid separates the male of F. tolgaensis   n. sp. and F. nervosae   and F. p oro s a e (respectively, 2–4 vs 5–6 and 4–5 annules in front of the secretory/excretory pore). The males of F. tolgaensis   n. sp. and F. rosettae   n. sp. are morphologically similar, but can be separated on the position of the hemizonid (4–5 vs 2 annules in front of the excretory pore), and the spicule is more slender in F. tolgaensis   n. sp.

Etymology. Named after Tolga, the locality on the Atherton Tableland, QLD, Australia from where the galls were collected.

TABLE 3. Measurements (µm) of Fergusobia tolgaensis n. sp. from various small galls on S. luehmannii (mean ± standard deviation; ranges in brackets).

n 20 17 4
Length 302 291±29.3 (243–344) 308±32.0 (268–349) 255±22.7 (223–272)
a 9.1 9.0±1.1 (7.0–11.0) 9.6±0.9 (7.8–11.1) 10.4±1.5 (8.0–12.0)
b’ 2.6 3.0±0.6 (2.0–4.0) 2.7±0.4 (2.0–3.4) 2.5±0.3 (2.0–3.0)
c 16.4 13.0±1.8 (11.0–17.0) 10.5±1.0 (8.9–13.2) 10.6±0.7 (9.8–12.0)
c’ 1.4 2.0±0.2 (1.4–2.1) 1.9±0.3 (1.4–2.4) 1.9±0.3 (1.6–2.2)
V% 88 85±3.4 (72–88)   83±0.9 (82–84)
T%   66±9.2 (50–77)  
Body diameter 33 32±4.7 (24–42) 32±4.7 (27–42) 25±2.3 (22–27)
Stylet length 8 8±0.7 (7–9) 9±0.9 (7–10) 7
Ant. end to SE pore 73 71±6.0 (63–85) 77±10.0 (60–96) 76±2.0 (71–81)
Spicule length   16±1.1 (14–18)  
Tail length 18 22±1.9 (18–25) 30±3.5 (24–36) 24±1.7 (22–25)
ANIC

Australian National Insect Collection

WINC

Waite Insect and Nematode Collection

USDA

United States Department of Agriculture