Fergusobia schmidti Davies & Bartholomaeus

Davies, Kerrie A., Bartholomaeus, Faerlie, Giblin-Davis, Robin M., Ye, Weimin, Taylor, Gary S. & Thomas, W. Kelley, 2014, Nematodes from galls on Myrtaceae. VIII. Fergusobia from small galls on shoot buds, with descriptions of four new species, Zootaxa 3857 (1), pp. 1-40 : 15-19

Fergusobia schmidti Davies & Bartholomaeus n. sp.

( Figs 5 , 7 S, 8U)

= Fergusobia MSp . 10 apud Davies et al. 2010a

Measurements. Table 4 .

Material examined. The description presented here is based on measurements of 31 parthenogenetic ♀s, 9 pre-parasitic infective ♀s, and 63 ♂ s. From roadside vegetation, Stonyfell, Adelaide, South Australia, Australia (3455.44S 13839.68E), and Erindale Shopping Centre, Erindale, Adelaide, South Australia, Australia (3455 S 13839 E). Taken from small, conoid, multilocular, stalked axial shoot bud galls on Eucalyptus camaldulensis . Respectively collected by K.A. Davies, 12.ix.2007 ( WINC 0 63799, WNC 2490) and K.A. Davies, 20.iii.1995, 31.v.1995, 27.iv.1996 ( WINC 0 0 4760, WNC 940).

Holotype. Parthenogenetic female, on a slide deposited in the ANIC, Canberra, ACT, Australia, together with an infective female and a male, collected at Stonyfell, Adelaide, South Australia, Australia, collection data as above.

Paratypes. Vouchers (collection data as above) deposited at the WINC, The University of Adelaide, SA, Australia, 25 parthenogenetic ♀s, 7 pre-parasitic infective ♀s, and 55 ♂ s; and at the USDA Nematode Collection, Beltsville, MD, USA 5 parthenogenetic ♀s, 1 pre-parasitic infective ♀, and 5 ♂ s.

Description. Parthenogenetic female. From small stalked axial leaf bud galls on E. camaldulensis . Body dorsally curved with ventral side convex to form open C to C-shaped; most curvature in posterior half; body narrows behind vulva to form conoid tail; smaller in size than the pre-parasitic infective female and the male. With light microscope, cuticle has obscure annules, and longitudinal striae are apparent. Lateral fields not seen.

Cephalic region occupying 63–87% diameter of body at anterior end, offset, ~ 2 µm high, unstriated; in lateral view has rounded outline and circum-oral area raised (~ 1µm high). Stylet well sclerotised, with conus ~ 50% of total stylet length, basal knobs ~ 2µm wide at base, and round.

Orifice of dorsal pharyngeal gland 1µm posterior to stylet knobs. Anterior fusiform part of digestive tract occupying 50–66 % of body diameter, 1.7–2.0 times diameter in length; lumen of tract broadens behind nerve ring. Pharyngeal glands extending over intestine, large to enormous, 50–80% of body diameter in diameter, distance from head to end of glands being 48 (33–59)% of total body length. In about half specimens examined, a prominent diverticulum extends into the anterior fusiform part of the digestive tract.

Secretory/excretory pore located at level of pharyngeal gland nucleus in some specimens, anterior to it in others; ovoid secretory/excretory cell ~ 3µm in diameter. Hemizonid extending over one annule, immediately anterior to secretory/excretory pore.

Reproductive tract comprising ovary with growth zone occupying ~ 60% of length, oviduct not clearly seen, no spermatheca, quadricolumella present, not smooth, uterine sac about one vulval body width in length. Reproductive tract variable in length, extending part-way along dorsal pharyngeal gland or to nerve ring, with up to 6 flexures extending to dorsal side; cap cell offset in some specimens; growth zone with one oocyte per row; uterine sac with no or one egg; vulva with rounded lips, flat or slightly (~ 1 or 2µm high) raised. Tail conoid, may be slightly concave on dorsal side, 1–1.5 times anal body diameter in length, tip bluntly to broadly rounded.

Infective pre-parasitic female. From small stalked axial leaf bud galls on E. camaldulensis . Penetrates mature larval stage of undescribed Fergusonina sp. or pupa. Body arcuate to open C to C-shaped when relaxed by heat; maximum body diameter at mid-body; cuticle with obscure annulations and longitudinal striae, loose in tail region of some specimens; lateral fields narrow, ~ 2µm wide, origin unclear.

Cephalic region barely offset, ~ 1 µm high; circum-oral area flat or barely raised; stylet slender, weakly sclerotised with rounded basal knobs being higher than wide, <2 µm in width; conus 40–50% of total stylet length.

Orifice of dorsal pharyngeal gland just posterior to stylet knobs. Anterior fusiform part of digestive tract occupying 50–70% of body diameter, 2–3 times diameter in length. Pharyngeal glands extending over intestine, relatively small, 15–40% body diameter in diameter, distance from head to end of glands being 40 (31–55)% of total body length.

Secretory/excretory pore opens at ~ 40–50% of length of pharyngeal gland; secretory/excretory cell not seen. Hemizonid not seen.

Uterus ~ 40% of total gonad length in uninseminated female, packed with amoeboid sperms in inseminated female; vagina at right angle to body axis; reproductive tract extending to nerve ring; hypertrophy of tract in most specimens. Vulval lips flat or barely raised. Tail short, broad, 0.5–1.5 times diameter at anus in length, tip variable, bluntly to broadly rounded or hemispherical.

Male. From small axial leaf bud galls on E. camaldulensis . Body arcuate to J- or C-shaped when relaxed by heat, tail region more or less curved ventrally. Cuticle with obscure annules ~ 1 µm wide, longitudinal striations apparent with light microscope; lateral fields ~ 4µm wide, no internal longitudinal ridges present; origin unclear.

Cephalic region offset, ~2 µm high; circum-oral area flat or raised ~1µm, with lightly sclerotised framework; stylet with conus 40–50% of length, round knobs ~ 1.5 µm in width.

Anterior fusiform part of digestive tract occupying ~50–75% of body diameter, 1.5–2.2 times diameter in length. Pharyngeal glands extending over intestine, ~ 70–80% of body diameter in diameter, distance from head to end of glands being 37(28–48)% of total body length; gland nucleus positioned at posterior end of gland in some specimens. Lumen of intestinal tract broadens behind pharyngeal glands.

Secretory/excretory pore opens at ~ 30–40% of length of pharyngeal gland and in front of gland nucleus; secretory/excretory cell ovoid, 3–5 µm in length. Hemizonid not seen.

Reproductive tract with single testis, variable in length, may not reach base of pharyngeal glands or extend to nerve ring; may be outstretched or reflexed; testis, seminal vesicle and vas deferens clearly differentiated in most specimens. Bursa membranous, smooth, peloderan; may be prominent or obscure; arises ~ 50% along length of body. Spicules paired, angular near their middle, small but robust; moderately sclerotised; manubrium offset dorsally, wider than shaft; blade narrows gradually; opening terminal. Inconspicuous muscles associated with cloaca. Tail ventrally concave, curved; 1–2.5 times diameter at cloaca in length, tip bluntly to broadly rounded.

Molecular phylogenetic relationships. For molecular analysis, the partial SSU ( KF209277 ) and the D2/D3 expansion segments of LSU ( KF209278 ) of V779 ( F. schmidti n. sp.) were sequenced. SSU in Fergusobia is a very conserved gene ( Ye et al. 2007), but the blastn search of SSU (1466 bp sequenced) revealed it has 4-bp differences (99% identity) with many Fergusobia species. The blastn search of LSU (854 bp sequenced) revealed F. schmidti n. sp. has 1–4-bp differences (99% identity) with V8 ( AY589313 ) (F. fi sheri), V25 ( AY589321 ), V26 ( AY589323 ), and V27 ( AY589322 ) (all MSp 38), V67 ( AY589356 ) ( F. microcarpae ) and V348 (MSp 37) ( AY589398 ). This molecular data corroborates the status of F. schmidti n. sp. as a unique species.

From phylogenetic analyses based on sequences of D2/D3 and mtCOI, F. schmidti n. sp. is inferred to be part of a clade which also contains pea gallers from E. marginata and E. pauciflora (respectively, Mspp 40 and 41), and F. r i l e yi from Corymbia sp. ( Ye et al. 2007; Davies et al. 2010a).

Diagnosis and relationships. Fergusobia schmidti n. sp. (MSp 10 of Davies et al. 2010a) is morphologically characterized by the combination of a small broad C-shaped parthenogenetic female with a variable, conoid tail, a small arcuate to open C-shaped infective female with a variable tail tip, and an arcuate, open C- or J-shaped male with a broad tail, angular spicule and peloderan bursa arising at ca half body length. Its status as a species is also supported by a combination of molecular analyses, its collection from small conoid axial bud galls (see Discussion), association with a fergusoninid fly having larvae with a shield comprising narrow bars of sclerotised cuticle and raised spicules, host E. camaldulensis , and wide geographic distribution (WA and SA).

All stages are morphologically similar to those of F. leucoxylonae n. sp., F. sporangae n. sp., F. microcarpae and F. porosae . In addition, parthenogenetic and infective females are similar to those of F. fisheri and F. gomphocephalae n. sp.

In body shape (open C to C-shaped), the parthenogenetic female of F. schmidti n. sp. differs from F. camaldulensae (arcuate); and F. rileyi (almost straight). In body length (251–356 µm), F. schmidti n. sp. is shorter than F. cosmophyllae (354–406 µm), F. delegatensae (345–527 µm), F. magna (500–780 µm), and F. i nd i ca (525–626 µm). The stylet (11–14 µm) of the parthenogenetic female of F. schmidti n. sp. is longer than that of F. brevicauda (8–8.5 µm), F. cajuputiae (8 µm), F. c o l b r an i (7–9 µm), F. curriei (5–8 µm), F. dealbatae (9–10 µm), F. gomphocephalae n. sp. (7–9 µm), F. leucadendrae (7–9 µm), F. fasciculosae (7–10 µm), F. fisheri (9–10 µm), F. nervosae (8–9 µm), F. microcarpae (9.5–11 µm), F. minimus (4–8 µm), F. philippinensis (7.5–9 µm), F. pohutukawa (10–11 µm), F. viminalisae (9–10 µm), and F. viridiflorae (7–9 µm). The a ratio (4–8) of the parthenogenetic female of F. schmidti n. sp. is smaller than that of F. brittenae (8–12) and F. eugenioidae (9–12), i.e. the latter are slimmer nematodes. In having large to enormous pharyngeal glands (b’ 1.7–3.0), it differs from F. jambophila which has smaller glands; and from F. quinquenerviae which has glands that are reflexed or have an extra lobe. The shape (conoid, with tail with bluntly to broadly rounded tip) of the body behind the vulva in F. schmidti n. sp. differs from that of F. dealbatae (more slender); F. diversifoliae (narrows more rapidly); F. pohutukawa (conoid, straight); F. floribundae , F. juliae , F. morrisae , F. pimpamensis , F. po ro s ae, and F. ptychocarpae (more slender, arcuate). The circum-oral area is raised in F. schmidti n. sp. but the opening for the stylet is not seen, separating the parthenogenetic female from that of F. sporangae n. sp. in which the opening is obvious. Morphologically, F. schmidti n. sp. is separated from the parthenogenetic females of F. gomphocephalae n. sp., F. leucoxylonae n. sp., F. planchonianae , and F. tumifaciens only by having a more distinctly raised circumoral area.

The infective female (arcuate or J-shaped or open C-shaped with strongly curved posterior region) of F. schmidti n. sp. is so variable that it differs in shape only from that of F. po ro s ae and F. rileyi (almost straight). However, it tends to be more curved than the infective female of F. camaldulensae , and lacks the raised vulval lips of the latter. In body length (252–395 µm), the female is smaller than F. magna (537–633 µm), F. curriei (417–489 µm), F. eugenioidae (438 µm), and F. juliae (396–550 µm); and tends to be smaller than F. ptychocarpae (387–471 µm) and F. rileyi (378–432 µm). The a ratio (6.5–10.8) of the infective female of F. schmidti n. sp. tends to be smaller than that of F. delegatensae (10.5–12) and F. floribundae (11–14), i.e. the latter are slimmer nematodes. In having a b’ ratio of 1.8–3.2, F. s c h m i d t i n. sp. differs from F. pimpamensis which has smaller glands (b’ 3.5–5.2). The cephalic area of the infective female of F. schmidti n. sp. is flat, differing from that of F. morrisae , in which it is dome-shaped; and from F. sporangae n. sp., in which the circum-oral area is raised. The infective female of F. schmidti n. sp. lacks a post-anal intestinal sac, which is present in F. philippinensis . Because the hemizonid and the lateral field of the infective female of F. schmidti n. sp. have not been seen, and given its variability in body size and shape, morphologically it is not possible to separate it from the same stage of F. brevicauda , F. brittenae , F. cajuputiae , F. colbrani , F. cosmophyllae , F. dealbatae , F. diversifoliae , F. fasciculosae , F. fisheri , F. gomphocephalae n. sp., F. leucadendrae , F. leucoxylonae n. sp., F. microcarpae , F. minimus , F. nervosae , F. planchonianae , F. quinquenerviae , F. tumifaciens , F. viminalisae , or F. viridiflorae .

In body shape (arcuate to J to open C-shaped), the male of F. schmidti n. sp. differs from those of F. jambophila (almost straight). The stylet (8–14 µm, mean 13) of F. schmidti n. sp. is longer than that of F. minimus (4–7 µm) and tends to be longer than that of F. cajuputiae (8 µm), F. c o l b r an i (7–10 µm, mean 8), F. floribundae (5–8 µm) and F. nervosae (7–8 µm). The male of F. schmidti n. sp. lacks the reflex or additional lobe of the pharyngeal gland that is seen in F. quinquenerviae . The male tail shape (arcuate with a bluntly to broadly rounded tip) of F. schmidti n. sp. differs from that of F. magna and F. viridiflorae (arcuate, more slender); and F. philippinensis (truncate tip). In having an angular shape, the spicule of F. schmidti n. sp. differs from that of F. camaldulensae and F. jambophila in which it is arcuate. The angle near mid-length of the spicule is larger in F. schmidti n. sp. than in F. gomphocephalae n. sp. The spicule is longer in F. schmidti n. sp. (19–25 µm) than in F. leucadendrae (14–17 µm) and tends to be longer than in F. nervosae (16–19 µm). Tail shape of F. schmidti n. sp. differs from that in F. ptychocarpae (bluntly vs broadly rounded tip). Fergusobia schmidti n. sp. has a bursa arising at ~ half body length; and it differs from F. cajuputiae (50–70% body length), F. diversifoliae (arising in front of excretory pore), F. morrisae (75–85%), F. pimpamensis (60–80%), F. planchonianae (60–80%), F. pohutukawa (arises near cephalic region), F. rileyi (>80%), F. viridiflorae (in front of nerve ring) in which it is longer; and from F. brevicauda (33%), F. brittenae (~ 20%), F. cosmophyllae (10–40%), F. curriei (~ 20%), F. dealbatae (30–50%), F. eugenioidae (~ 25%), F. fasciculosae (25–45%), F. fisheri (20–50%), F. gomphocephalae n. sp. (30–50%), F. juliae (25–40%), F. leucoxylonae n. sp. (20–30%), F. microcarpae (25–45%), F. porosae (15–33%), F. sporangae n. sp. (10–40%), F. tumifaciens (9–16%), and F. viminalisae (30–40%), in which it is shorter. The bursa of F. schmidti n. sp. is smooth, but crenate in F. delegatensae , F. planchonianae and F. tumifaciens .

Etymology. Named in memory of Professor Otto Schmidt , late of The University of Adelaide, Adelaide, South Australia; in recognition of his contributions to insect physiology, and in gratitude for discussions about how Fergusobia might escape the fergusoninid fly’s immunological system.

Figures

FIGURE 5. Fergusobia sporangae n. sp. (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.

FIGURE 7. Spicules from Fergusobia spp. collected from small shoot bud galls: A, MSp 40 from E. marginata; B, F. rileyi; C, MSp 61 from E. delegatensis; D, MSp 55 from E. amygdalina; E, MSp 78 from E. blakelyi; F, MSp 59 from E. obliqua; G, MSp 41 from E. pauciflora; H, Fergusobia sp. from ABG from Eucalyptus sp. at Brisbane, QLD; I, MSp 30 from E. tereticornis; J, F. gomphocephalae n. sp.; K, F. leucoxylonae n. sp.; L, F. sporangae n. sp.; M, MSp 21 from E. microcarpae; N, Fergusobia sp. from E. odorata; O, MSp 28 from E.? siderophloia; P, MSp 39 from E. viminalis UABG form 2; Q, MSp 79 from E. fasciculosae; R, MSp 47 from E. cladocalyx; S, MSp 77 from E. confluens; T, Fergusobia sp. from LPG from Eucalyptus sp. at Indooroopilly, Brisbane, QLD; U, F. schmidti n. sp. Not drawn to scale.

Tables

TABLE 4. Measurements (µm) of Fergusobia schmidti n. sp. from Eucalyptus camaldulensis. (Mean ± standard deviation, with range in brackets).

	Holotype Partheno-genetic female	Parthenogenetic females	Males	Infective females
n	1	25	24	13
Length	298	294±25.1 (251 – 356)	356±51.8 (274 – 505)	302±44.5 (252 – 395)
a	8.3	6.7±1.1 (5.2 – 9.1)	8.6±1.7 (6.0 – 11.7)	8.3±1.4 (6.5 – 10.8)
b’	2.1	2.1±0.4 (1.7 – 3.0)	2.7±0.3 (2.1 – 3.5)	2.5±0.7 (1.8 – 3.2)
c	13.1	14.4±2.0 (9.9 – 17.3)	8.7±1.2 (7.0 – 12.5)	15.3±5.0 (10.1 – 28.1)
c’	1.0	1.2±0.2 (0.9 – 1.8)	1.8±0.4 (1.1 – 2.5)	0.8±0.3 (0.5 – 1.4)
V or T %	82.9	84.1±2.8 (78.5 – 92.2)	55.3±14.3 (29.4 – 81.1)	82.1±2.4 (77.3 – 85.2)
Body diameter	37	49±11.3 (37 – 60)	42±4.9 (35 – 56)	37±5.4 (30 – 48)
Stylet length	13.5	13±1.1 (11 – 14)	10±1.8 (8 – 14)	7±2.2 (5 – 10)
Ant. end to SE pore	84	81±8.3 (70 – 96)	89±16.5 (68 – 118)	68±8.4 (57 – 79)
Spicule length			23±1.7 (19 – 25)
Tail length	23	21±3.7 (16 – 30)	42±8.6 (26 – 59)	21±5.5 (10 – 29)