Fergusobia linariifoliae, Davies, Kerrie A., Giblin-Davis, Robin M., Ye, Weimin, Taylor, Gary S., Makinson, Jeff & Purcell, Matthew, 2014

Davies, Kerrie A., Giblin-Davis, Robin M., Ye, Weimin, Taylor, Gary S., Makinson, Jeff & Purcell, Matthew, 2014, Nematodes from galls on Myrtaceae. X. Fergusobia from galls on narrow-leaved Melaleuca spp. in Australia, with descriptions of three new species, Zootaxa 3889 (2), pp. 237-258 : 247-252

Description of Fergusobia linariifoliae n. sp. Davies

( Figs 3 , 4 C)

= Fergusobia MSp 19 apud Davies et al. (2012a)

Measurements. Table 4 .

Material examined. The description presented here is based on measurements of 9 parthenogenetic ♀s, 2 infective ♀s and 16 ♂ s; Port Macquarie Racecourse, Port Macquarie, New South Wales (31°26.29´S 152°52.79´E). Taken from unilocular axial bud galls on Melaleuca linariifoliae Smith 1797 . Collected by K.A. Davies & R. M. Giblin-Davis, 6.vii.2004.

Holotype. One parthenogenetic female, together with an infective female and a male, on a slide deposited in the ANIC, Canberra, ACT, Australia; collection data as above.

Paratypes. Vouchers (collection data as above) deposited at the WINC, The University of Adelaide, SA, Australia, 3 parthenogenetic females and 8 males on slides numbered WINC 0 0 4348, (WNC 2376); at the Australian Museum, Sydney, NSW, Australia, 4 parthenogenetic females, 1 infective female and 6 males on slides; and at the USDA Nematode Collection, Beltsville, MD, USA 1 parthenogenetic female and 1 male on a slide.

Description. Parthenogenetic female. Body shape variable, straight to arcuate to open C-shaped, with most curvature posterior to vulva; relatively small; relatively broad; similar in size to amphimictic pre-parasitic females and to males; body narrows behind vulva to form a conoid tail. Cuticle appears swollen when fixed, sub-cuticle with strong longitudinal striae. Lateral fields not seen.

Cephalic region ~ 80% diameter of body at anterior end, offset, 2 µm high, unstriated; rounded outline in lateral view, circum-oral area flat or depressed. Amphids not seen. Stylet strongly sclerotised, with cone occupying 30–40% of length, basal knobs just higher than wide, 2–3 µm wide at base, rounded.

Orifice of dorsal pharyngeal gland ~ 1 µm posterior to stylet knobs. Anterior fusiform part of digestive tract occupying 44 (34–57)% body diameter, length 1.5–2.5 times diameter; lumen of tract broadens at distal end of dorsal pharyngeal gland. Pharyngeal glands often obscure, extending over intestine, occupying 43 (35–52)% of body diameter, distance from head to end of glands being 30 (22–37)% of total body length. Gland nucleus large, with large nucleolus.

Secretory/excretory pore opens behind nucleus of pharyngeal gland; duct obscure; secretory/excretory cell wedge-shaped, ~ 5 µm long. Hemizonid not seen.

Reproductive tract extending to nerve ring or anterior to it; flexed in 5/ 9 specimens examined; oviduct usually with one oocyte per row; quadricolumella with obvious clustered cells, not smooth; uterus long and extensile (up to 60% of body length), usually with 2 or more eggs and occasionally juveniles; vulva a simple transverse slit with flat lips; no vulval plate. Probably ovoviviparous. Anus pore-like. Tail conoid, barely concave on ventral side; length 0.5–1.5 times anal body diameter; tip broadly rounded.

Infective pre-parasitic female. Almost body straight when relaxed by heat; relatively broad; maximum body diameter at mid-body; body tapers gradually in tail region. Cuticle obscurely annulated, <1 µm wide; longitudinal striae apparent with light microscope; lateral fields not seen.

Cephalic region not offset, domed shape; circum-oral area rounded; stylet slender, weakly sclerotised with small basal knobs being higher than wide; <2µm wide; cone ~ 30% of stylet length.

Orifice of dorsal pharyngeal gland often obscure, ~1 µm posterior to stylet knobs. Anterior fusiform part of digestive tract little expanded, occupying 34–42% of body diameter, length 2.2 times diameter. Pharyngeal glands extending over intestine, occupying 42–44% body diameter, distance from head to end of glands being ~25% of total body length.

Secretory/excretory pore opens behind pharyngeal glands; duct obscure. Hemizonid 1 or 2 annuli in front of pore.

Uterus packed with sperms in inseminated females; vagina at right angle to body axis; length of reproductive tract hypertrophied in some specimens. Vulva a transverse slit, vulval lips raised ~ 1 µm, no vulval plate present. Anus an obscure pore. Tail conoid; length ~ 1.5 times diameter at anus, tip broadly rounded.

Male. Body straight to arcuate when relaxed by heat, tail region slightly curved ventrally. Cuticle clearly annulated, annuli ~1µm wide; strong longitudinal striae apparent with light microscope; lateral fields not seen.

Cephalic region occupying 73–87% anterior body diameter, offset, ~ 2 µm high; circum-oral area flat or barely raised, with lightly sclerotised framework; stylet long, with cone occupying 40% of length, small round stylet knobs <2 µm wide.

Orifice of dorsal pharyngeal gland ~ 1 µm behind knobs. Anterior fusiform part of digestive tract occupying 41–61% of body diameter, length 1.8–2.6 times diameter. Pharyngeal glands extending over intestine, occupying 45 (28–85)% of body diameter, distance from head to end of glands being 24 (20–36)% of total body length. Lumen of intestinal tract broadens behind pharyngeal gland.

Secretory/excretory pore opens opposite nucleus of pharyngeal gland; duct obscure; secretory/excretory cell ~ 5 µm long. Hemizonid lens-like, extending over two annules, 8 annuli in front of secretory/excretory pore.

Reproductive tract with single testis, variable in length, usually extends to nerve ring but may extend anterior to it; usually reflexed; testis, seminal vesicle and vas deferens not clearly differentiated. Bursa peloderan (but usually appears to be leptoderan), smooth; may be prominent or obscure; arises ~ 90% along length of body, in front of secretory/excretory pore. Spicules paired, angular at ~ 40–50% of length, with manubrium and shaft longer than blade; moderately sclerotised; manubrium similar to or wider than shaft, not offset dorsally; blade narrows unevenly to bluntly rounded tip with concavity on distal edge; opening sub-terminal. Inconspicuous muscles associated with cloaca. Tail arcuate, ventrally concave, conoid; length 2.0–3.1 times diameter at cloaca; broadly rounded tip.

Molecular relationships. With SSU, the blastn search of F. linariifoliae n. sp. (V 412) ( FJ393270 , 1686 bp sequenced) revealed it has more than 6 bp differences (99% identity) from many Fergusobia species. The blastn search on D2/D3 of V 412 ( FJ386996 , 870 bp sequenced) suugested it has more than 40 bp differences (95% identity) and 16 gaps from V 405 ( FJ386994 ) and V 410 ( FJ386995 ) (both F. armillarisae n. sp.). With COI, the blastn search ( FJ386969 , 618 bp sequenced) suggested the highest match with other Fergusobia species was 56 bp differences (91% identity). These large sequence divergences support F. linariifoliae n. sp. as a unique species.

Diagnosis and relationships. Fergusobia linariifoliae n. sp. is morphologically characterized by the combination of a medium sized, arcuate, parthenogenetic female in which the cuticle swells upon fixation, having a small stylet and extensile uterus containing up to 5 eggs, with short conoid tail with a bluntly rounded tip; a small, arcuate, infective female with a broadly rounded tail tip; and small arcuate males with arcuate to angular (not heavily sclerotised) spicules and bursa arising near the secretory/excretory pore. Morphologically, F. linariifoliae n. sp. is similar to F. armillarisae n. sp. However, it differs in that the cuticle of the parthenogenetic females of the latter does not swell upon fixation. In length (347–384 µm), the infective females are larger than those of F. armillarisae n. sp. (279–291 µm). In males of F. linariifoliae n. sp., the bursa arises at ~ 90% of body length, separating them from those of F. armillarisae n. sp. (50%–80%).

Parthenogenetic females of F. linariifoliae n. sp. (arcuate shape) differ from F. brevicauda , F. brittenae , F. cosmophyllae , F. diversifoliae , F. fasciculosae , F. floribundae , F. gomphocephalae , F. indica , F. leucoxylonae , F. magna , F. microcarpae , F. minimus , F. morrisae , F. pimpamensis , F. schmidti , F. planchonianae , F. porosae , F. ptychocarpae , F. viminalisae , and F. viridiflorae (C-shape). In having an extensile uterus, they differ from F. cajuputiae , F. colbrani , F. dealbatae , F. delegatensae , F. eugenioidae , F. fisheri , F. leucadendrae , F. morrisae , F. nervosa , F. philippinensis , F. rosettae , F. sporangae , F. tolgarae , and F. tumifaciens , in which it is not extensile. In having cuticle which may swell upon fixation; they differ from F. decorae n. sp., in which it does not. Having a flat circum-oral area separates parthenogenetic females of F. linariifoliae n. sp. and those of F. camaldulensae and F. jambophila , in which it is raised. The stylet (10–12 µm) of these parthenogenetic females is longer than in F. curriei (5–8 µm), F. juliae (5–7 µm) and F. minimus (4–8 µm). In having large oesophageal glands, they are similar to F. quinquenerviae but lack the extra lobe or flex found in glands of the latter. In F. linariifoliae n. sp., the vulva (85%–89%) is more posterior than in F. nervosae (81%–83%). In having a body behind the vulva that narrows gradually, is arcuate and conoid in shape, with a broadly rounded tip, these females differ from F. pohutukawa (with a narrowly rounded tip that may have a mucron) and F. rileyi (more slender, arcuate to straight).

Infective females of F. linariifoliae n. sp. (almost straight) differ in shape from F. dealbatae , F. diversifoliae , F. fasciculosae , F. gomphocephalae , F. leucadendrae , F. nervosae , F. pimpamensis , F. philippinensis , F. sporangae , and F. viminalisae (open C-shape); and from F. floribundae and F. morrisae (J shape). In length (347–384 µm), they are smaller than females of F. brittenae (375–550 µm), F. cosmophyllae (374–448 µm), F. eugenioidae (438 µm), F. juliae (396–550 µm), F. magna (537–633 µm), and F. ptychocarpae (387–471 µm); and larger than those of F. cajuputiae (239–309 µm), F. decorae n. sp. (207–256 µm), F. quinquenerviae (259–325 µm), and F. tolgarae (223–272 µm). The stylet (11–14 µm) is longer than in F. colbrani (8.5 µm), F. minimus (4–5.5 µm), F. schmidti (5–10 µm) and F. tumifaciens (6.5–9.5 µm). These infective females have longer tails than those of F. colbrani and F. decorae n. sp. (respectively, 18–23 and 29–30 vs 13–18 µm); and shorter than those of F. rileyi (40–50 µm). They have sub-cylindroid tails with tips that are broadly rounded, separating them from F. camaldulensae , F. curriei , F. delegatensae , F. fisheri , F. leucoxylonae , F. microcarpae , F. planchonianae , and F. ro s e t t ae (tail tips almost hemispherical), and from F. po ro s ae (tail tips bluntly rounded). The infective females of F. viridiflorae may have shorter tails than those of F. linariifoliae n. sp. (23 vs 29–30 µm), but with such small numbers examined (1 vs 2 specimens) it is not possible to be definite. Similarly, using Siddiqi’s (1994) description, infective females of F. linariifoliae n. sp. may be less curved when heat fixed than those of F. brevicauda , and the ratio c’ is smaller in F. brevicauda (1.4–1.5 vs 0.9–1.1).

In shape (straight to arcuate), the males of F. linariifoliae n. sp. differ from those of F. brittenae , F. curriei , and F. fasciculosae (J-shape), F. pimpamensis (J or C-shape), F. diversifoliae , F. juliae , F. magna , F. planchonianae , F. ptychocarpae , and F. viridiflorae (with strongly curved posterior). In having a flat circum-oral area, these males are separated from F. camaldulensae , F. jambophila , and F. tolgarae in which it is raised. The length of the tail in males of F. linariifoliae n. sp. is longer than in F. colbrani (36–53 vs 28–36 µm). The shape of the tail (arcuate with a broadly rounded tip) differs from that of F. philippinensis (truncate tip), F. r i l e yi (slender, straight, with bluntly rounded tip) and from F. leucadendrae (bluntly rounded tip). In having arcuate to angular spicules, F. linariifoliae n. sp. differs from F. brevicauda , F. cajuputiae , F. dealbatae , F. delegatensae , F. eugenioidae , F. floribundae , F. gomphocephalae , F. leucadendrae , F. microcarpae , F. morrisae , F. pohutukawa , F. quinquenerviae , F. tumifaciens , and F. viminalisae , in which it is clearly angular. In males of F. linariifoliae n. sp., the bursa arises at ~ 90% of body length, separating them from those of F. cosmophyllae (~ 10%–40%), F. decorae n. sp. (~ 30%–50%), F. f i s h e r i (~ 20%), F. minimus (10%–30%), F. nervosae (~ 50%), F. schmidti (~ 50%), F. p oro s a e (15%–33%), F. rosett ae (~ 40%–50%), F. sporangae (10%–40%), and F. tumifaciens (9%–16%).

Etymology. Named after M. linariifolia , the plant species from which the nematodes were collected.

Figures

FIGURE 3. Fergusobia linariifoliae n. sp. (all in lateral view): A, Entire parthenogenetic female; B, Head of parthenogenetic female with cuticle separation; C, Head of parthenogenetic female without cuticle separation; D, Habitus; E, Tails of parthenogenetic females; F, Entire infective female; G, Head of infective female; H; Habitus; I, Entire male; J, Head of male; K, Habitus; L, Tails of males. Scale bars: A, F, I = 50 Μm. B, C, G, J = 5 Μm. Tails not drawn to scale.

FIGURE 4. Spicules from Fergusobia spp. collected from galls on narrow-leaved Melaleuca spp.: A, from M. armillaris; B, from M. decora; C, from M. linariifolia. Scale bar = 5 µm.

Tables

TABLE 4. Measurements (µm) of Fergusobia linariifoliae n. sp. from Melaleuca linariifolia. (Mean ± standard deviation, with range in brackets).

	Holotype Partheno genetic female	Parthenogenetic females	Males	Infective females
N		9	16	2
Length	360	341±46.0 (271–399)	406±25.6 (360–440)	365 (347–384)
a	10.6	7.2±2.0 (4.6–10.6)	10.4±0.9 (8.8–12.1)	9.5 (9.3–9.8)
b’	2.8	3.3±0.6 (2.7–4.6)	4.1±0.9 (2.8–5.1)	4.3 (4.2–4.3)
c	25.3	18.9±5.4 (14.1–28.0)	8.6±0.8 (7.2–10.1)	12.5 (11.5–13.5)
c’	0.8	1.0±0.3 (0.5–1.4)	2.5±0.3 (2.0–3.1)	1.4 (1.4–1.5)
V or T%	88	86.8±1.5 (85–89)	79.7±2.7 (75–84)	82.5 (82–83)
Body diameter	34	49±8.1 (34–59)	39±2.9 (34–45)	38 (37–39)
Stylet length	11	11±0.9 (10–12)	10±0.8 (9–12)	12.5 (11– 14)
Ant. end to SE pore	94	78±34 (27–110)	98±22 (71–125)	94 (91–96)
Spicule length			20.4±1.2 (19–23)
Tail length	14	19.0±5.4 (14–25)	47.0±5.1 (36–53)	29.5 (29–30)