Fergusobia sporangae Davies

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 : 20-27

Fergusobia sporangae Davies n. sp.

( Figs 6 , 7 K, 8L)

= Fergusobia MSp . 16 apud Davies et al. 2010a

Measurements. Table 5 .

Material examined. The description presented here is based on measurements of 17 parthenogenetic ♀s, 20 pre-parasitic infective ♀s, and 20 ♂ s. From planted garden and parkland trees; Erindale, Adelaide, SA, Australia (3455 S 13839 E) ( WINC 0 0 4752, WNC 2080); Urrbrae, Adelaide, SA, Australia (3458.16S 13837.93E) ( WINC 004273-4, WNC 2099); Kensington Park, Adelaide, SA, Australia (3455.45S 13839.76E) ( WINC 0 0 4381, 004444–5, 004551–3, WNC 2284); Stonyfell, Adelaide, SA, Australia (3455.76S 13840.26E) ( WINC 0 63710, WNC 2471). Taken from unilocular axial ‘pea’ galls, usually stalked, rarely sessile, on Eucalyptus leucoxylon . Respectively collected by K.A. Davies, 20.v.2000; G.S. Taylor, 9.viii.2000; K.A. Davies, 10.ix.2002; and K.A. Davies, 20.viii.2005.

Holotype. Parthenogenetic female on a slide deposited in the ANIC, Canberra, ACT, Australia, together with an infective female and a male; collected at Kensington Park, Kensington Park, Adelaide, SA, by K.A. Davies, 10.ix.2002 (WNC 2284).

Paratypes. Vouchers (collection data as above) deposited at the WINC, The University of Adelaide, SA, Australia, 10 parthenogenetic ♀s, 14 pre-parasitic infective ♀s, and 12 ♂ s; and at the USDA Nematode Collection, Beltsville, MD, USA 5 parthenogenetic ♀s, 4 pre-parasitic infective ♀s, and 5 ♂ s.

Description. Parthenogenetic female. From unilocular axial ‘pea’ galls on E. leucoxylon . Body arcuate to open C-shaped when heat-relaxed, most curvature in posterior third of body, dorsally curved with ventral side convex; similar in size to the pre-parasitic infective female and smaller than the male; body narrows gradually behind vulva. Cuticle smooth, obscurely annulated, longitudinal striae apparent with light microscope; lateral fields not seen.

Cephalic region occupying 65–85 % diameter of body at anterior end, usually offset, 3–3.5 µm high; unstriated; in lateral view has rounded outline and circum-oral area raised with broad opening. Stylet 12–14 µm long, with conus 30% of total stylet length, basal knobs well defined, 2–3 µm wide at base, rounded.

Orifice of dorsal pharyngeal gland 1–2 µm posterior to stylet knobs. Anterior fusiform part of digestive tract occupying ~ 70–80 % of body diameter, 1.8–2.8 times diameter in length, lumen of tract broadens near end of dorsal pharyngeal gland. Pharyngeal glands extending over intestine, enormous, ~50–75% of body diameter in diameter, distance from head to end of glands being 59 (48–67)% of total body length.

Secretory/excretory pore opens 57–93 µm from anterior end with weakly sclerotised duct; secretory/excretory cell not seen. Hemizonid immediately anterior to pore, extending over 2 annules.

Reproductive tract comprising ovary with growth zone occupying ~ 70% of length, structure of oviduct obscure, no spermatheca, quadricolumella present, smooth, uterine sac less than one vulval body diameter in length. Tract variable in length, usually outstretched on right side of intestine, with 1 flexure to ventral side in one specimen, extending part way along pharyngeal gland or to nerve ring; growth zone usually with first few oocytes in a single row, then forming two, and finally one per row; uterine sac containing no eggs or one egg (in 2 of 17 specimens examined); vulva a depressed slit, vulval lips usually slightly raised. Tail variable in length and diameter, 1–1.5 times anal body diameter in length, with a broadly rounded tip.

Infective pre-parasitic female. From unilocular axial ‘pea’ galls on E. leucoxylon . Penetrates mature larval stage of Fergusonina sp. or pupa. Body arcuate when relaxed by heat, with most curvature in posterior third of body; maximum body diameter at mid-body or at vulva; cuticle smooth, longitudinal striae apparent with light microscope; lateral fields not seen.

Cephalic region occupying 65–75 % diameter of body at anterior end, usually off-set, 1.4–2.2 µm high. Circum-oral area barely raised, with broad opening; stylet slender, 7–9µm long, weakly sclerotised with round basal knobs ~ 2µm in width; conus 30% of total stylet length.

Orifice of dorsal pharyngeal gland ~ 2µm posterior to stylet knobs. Anterior fusiform part of digestive tract occupying ~ 55–75% of body diameter. Pharyngeal glands extending over intestine, 23–57% of body diameter in diameter, distance from head to end of glands being 41 (25–50)% of total body length.

Secretory/excretory pore opens 65–94 µm behind anterior end, about a third along length of pharyngeal glands; secretory/excretory cell not seen. Hemizonid extending over two annules, immediately anterior to secretory/excretory pore.

Uterus ~ 40% of length of reproductive tract in uninseminated female, packed with amoeboid sperms in inseminated female; vagina sloping towards tail end; reproductive tract extending to nerve ring; hypertrophy of tract in some specimens. Vulval lips slightly raised. Prominent epidermal nuclei seen on tail. Tail as long as diameter at anus, tip broadly rounded to hemispherical.

Male. From unilocular axial ‘pea’ galls on E. leucoxylon . Body almost straight to barely J-shaped when relaxed by heat, tail region more or less curved ventrally. Cuticle smooth, annuless obscure, clear longitudinal striae apparent with light microscope; lateral fields not seen.

Cephalic region occupying 70–77 % anterior body diameter, 1.4–2.5 µm high, circum-oral area raised with broad opening, with lightly sclerotised framework; stylet 9–10 µm long, with conus 25–30% of length, round stylet knobs ~ 2µm in width.

Anterior fusiform part of digestive tract occupying ~ 60–80% of body diameter. Pharyngeal glands extending over intestine, ~ 60–70% of body diameter in diameter, distance from head to end of glands being 40% (27–51%) of total body length. Lumen of intestinal tract broadens behind gland.

Secretory/excretory pore opens 72–104 µm behind anterior end, at about half length of pharyngeal gland; secretory/excretory cell not seen. Hemizonid extending over 2–3 annules, at level of secretory/excretory pore.

Reproductive tract with single testis, variable in length, usually overlaps dorsal pharyngeal gland; may be reflexed; testis, seminal vesicle and vas deferens clearly differentiated in specimens with less developed tract; vas deferens variable in length, muscular region of vas deferens small or not apparent. Bursa smooth; peloderan; arises ~10–40% along length of body. Spicules paired, angular near their middle, broad, not heavily sclerotised; manubrium wider than shaft, not off-set; opening obscure. Conspicuous muscles associated with cloaca. Tail length 1.3–2 times diameter at cloaca, with a rounded tip.

Molecular analysis. No molecular data is available for this species.

Diagnosis and relationships. Fergusobia sporangae n. sp. (MSp 16 of Davies et al. 2010a) is morphologically characterized by the combination of an arcuate to open C-shaped parthenogenetic female with a broadly rounded tail tip, an arcuate infective female with a short tail with a broadly rounded to hemispherical tip, and an arcuate to barely J-shaped male with angular (not heavily sclerotised) spicule and short peloderan bursa. Its status as a species is also supported by a combination of its collection from unilocular axial bud galls (see Discussion), association with a fergusoninid fly having larvae with a shield of the ‘patches’ form, host E. leucoxylon , and geographic distribution (collected only within the natural range of the host plant in SA).

Morphologically, Fergusobia sporangae n. sp. is similar to F. gomphocephalae n. sp., F. microcarpae , F. leucoxylonae n. sp., and F. f i s h e r i.

The parthenogenetic female of F. sporangae n. sp. (arcuate to open C-shaped) differs from F. brittenae , F. cosmophylla , F. floribundae , F. indi ca, F. magna , F. minimus , F. morrisae , and F. ptychocarpae (C-shaped). In body length (221–319 µm), F. sporangae n. sp. is shorter than the parthenogenetic female of F. brittenae (328–461 µm), F. cosmophylla (354–406 µm), F. delegatensae (345–527 µm), F. floribundae (352–466 µm), F. i n di c a (525–626 µm), and F. magna (418–780 µm). The stylet (12–14 µm) of the parthenogenetic female of F. sporangae n. sp. is longer than that of F. brevicauda (8-8.5 µm), F. cajuputiae (8 µm), F. curriei (5-8 µm), F. eugenioides (9-11 µm), F. fasciculosae (7-10 µm), F. fi sheri (9-10 µm), F.gomphocephalae (7-9 µm), F. juliae (5-7 µm), F. leucadendrae (8 µm), F. microcarpae (9.5-11 µm), F. nervosae (8-9 µm), F.porosae (8.8-9.5 µm), F. quinquenerviae (6-9 µm), and F.viridiflorae (7-9 µm); and apparently shorter than that of F. tumifaciens (19 µm). The circum-oral area is clearly raised in F. sporangae n. sp. and the opening for the stylet is obvious, separating the parthenogenetic female from that of F. colbrani , F. planchoniana , F. schmidti n. sp., F. tumifaciens , and F. viminalisae in which the opening cannot be seen. In having a body behind the vulva that is arcuate with a broadly rounded tip, the female of F. sporangae n. sp. differs from F. pohutukawa (straight, conoid); from F. dealbatae , F. floribundae , F. philippinensis , F. pimpamensis , and F. rileyi (more slender, arcuate to straight); and from F. diversifoliae (narrow rapidly behind the vulva). In length (11–22 µm), the tail of the F. sporangae n. sp. parthenogenetic female is shorter than in F. indica (50–65 µm). The ratio c (12.4–23.3) in this parthenogenetic female is larger than that of F. tumifaciens (10.5). Ratio c’ (0.8–1.6) is smaller than in F. philippinensis (1.9–2.3).

The infective females of F. sporangae n. sp. (arcuate with most curvature behind vulva) differs in shape from F. magna , F. brittenae , F. curriei , and F. gomphocephalae n. sp. (open C-shaped); from F. eugenioidae (posterior more curved); and from F. po ro s ae and F. rileyi (almost straight). In body length (289–353 µm), F. sporangae n. sp. is smaller than the female of F. magna (537–633 µm), F. brittenae (375–550 µm), F. cosmophyllae (374–448 µm), F. curriei (417–489 µm), F. delegatensae (375–452 µm), F. juliae (396–550 µm), F. pimpamensis (369–443 µm), F. ptychocarpae (387–471 µm), and F. rileyi (378–432 µm). The stylet (7–10 µm) of F. sporangae n. sp. is longer than in F. microcarpae (6–7 µm). In shape, the tail tip (broadly rounded), F. sporangae n. sp. differs from that of F. philippinensis (sub-truncate). The tail (11–24 µm) tends to be shorter than in F. f i s h e r i (21–49 µm). The ratio c (13.9–26.0) of the infective female of F. sporangae n. sp. is larger than in F. leucadendrae (9.1–11.7); and the ratio c’ (0.5–1.1) is smaller than in F. dealbatae (1.3–1.7), F. j u l i a e (1.2–2.0), and F. leucadendrae (1.5–1.6). In having a raised circum-oral area with a relatively wide opening for the stylet, the infective female o f F. sporangae n. sp. differs from F. cajuputiae , F. colbrani , F. leucoxylonae , F. minimus , F. nervosa , F. planchoniana , F. quinquenerviae , F. tumifaciens , F. viminalisae , and F. viridiflorae , in which it is either flat or depressed and which have narrow openings; and from F. camaldulaensae , F. fasciculosae and F. diversifoliae which have a narrow opening. Using Siddiqi’s description (1994), F. sporangae n. sp. cannot be separated from F. brevifolia . In addition, it cannot be separated from F. schmidt i n. sp.

In shape (almost straight to J-shaped), the male of F. sporangae n. sp. differs from F. brittenae , F. fasciculosae , F. juliae , and F. nervosae (with strongly curved posterior regions). In body length (292–400 µm), F. sporangae n. sp. is larger than the male of F. gomphocephalae n. sp. (228–283 µm); and smaller than that of F. magna (446–588 µm), F. diversifoliae (413–459 µm), and F. pimpamensis (407–525 µm). The stylet of F. sporangae n. sp. (9–10 µm) is longer than in F. floribundae (5–8 µm), F. minimus (4–7 µm), and F. nervosae (7–8 µm); and shorter than in F. r i l ey i (11–13 µm). The shape of the tail (arcuate with a broadly rounded tip) of F. sporangae n. sp. differs from that of F. philippinensis (truncate tip); and from F. rileyi and F. viridiflorae (more slender, straight to arcuate, with bluntly or narrowly rounded tips). In length (19–35 µm), the male tail of F. sporangae n. sp. is shorter than in F. curriei (36–38 µm), F. pimpamensis (41–57 µm) and F. pohutukawa (50–61 µm). The ratio c (10.5–16.3) of the male of F. sporangae n. sp. is greater than that of F. cajuputiae (6.8–9.6), F. dealbatae (8.3–10), F. nervosae (8.2–9.2), and F. ptychocarpae (7.6–8.6), and the ratio c’ (1.3–2.0) is smaller than in F. cajuputiae (2–3.1) and F. dealbata (2–2.7). (2.7–4.2). The spicule (16.5–21 µm) of F. sporangae n. sp. is shorter than in F. eugeniodae (23–25 µm) and longer than in F. cosmophyllae (12–15 µm), and F. porosae (11–15.5 µm). In having an angular spicule, F. sporangae n. sp. differs from F. jambophila , in which it is arcuate. The bursa of males of F. sporangae n. sp. is short (extending anteriorly to 10–40% of body length); differing from F. brevicauda , F. camaldulensae , F. delegatensae , F. leucadendrae , and F. planchonianae in which the bursa is longer. The male of F. sporangae n. sp. is separated from F. leucoxylonae n. sp. and F. microcarpae by having a spicule lacking an offset manubrium. It can be separated from F. morrisae by tending to have a broader tail. Position of the hemizonid can be used to separate F. sporangae n. sp. and F. quinquenerviae males (respectively, immediately vs 2–6 annules anterior to the secretory/excretory pore), and the latter have larger pharyngeal glands. The circum-oral area of the male of F. sporangae n. sp. has an obvious opening for the stylet, which separates it from F. colbrani , F. f i s h er i, F. po ro s ae, F. schmidti n. sp., F. tumifaciens , and F. viminalisae , which do not.

Remarks. Six collections of unilocular axial bud galls were made from E. leucoxylon , and most of the galls within these collections were stalked. However, one sessile axial ‘pea’ gall was found associated with F. sporangae n. sp.

Etymology. Named for the usual form of the gall, superficially resembling a sporangium, from which the nematodes were collected.

Figures

FIGURE 6. Habitus drawings of Fergusobia spp. (most undescribed) collected from small shoot bud galls: A, MSp 40 from LPG on E. marginata; B, F. rileyi from LPG on Corymbia sp.; C, MSp 61 from LPG on E. delegatensis; D, MSp 55 from LPG on E. amygdalina; E, MSp 78 from petiole PG on E. blakelyi; F, MSp 59 from LPG on E. obliqua; G, MSp 41 from LPG on E. pauciflora; H, MSp 30 from LPG on E. tereticornis; I, F. gomphocephalae n. sp. from unilocular stem and bud galls on E. gomphocephala; J, F. leucoxylonaeae n. sp. from multilocular shoot bud galls on E. leucoxylon; K, F. sporangae n. sp. from UABG on E. leucoxylon; L, MSp 21 from UABG on E. microcarpa; M, Fergusobia sp. from UABG on E. odorata; N, MSp 80 from UABG on E. viminalis; O, MSp 79 from multilocular shoot bud gall on E. fasciculosa; P, MSp 47 from AUBG on E. cladocalyx; Q, MSp 77 from multilocular shoot bud gall on E. confluens; R, MSp 39 from UABG form 2 on E. viminalis; S, F. schmidti n. sp. from multilocular conoid axial shoot bud gall on E. camaldulensis. Scale bars = 50 µm.

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 5. Measurements (µm) of Fergusobia sporangae n. sp. from Eucalyptus leucoxylon. (Mean ± standard deviation, with range in brackets)

	Holotype Partheno-genetic female	Parthenogenetic females	Males	Infective females
n	1	17	20	20
Length	249	266±17 (221 – 319)	339±23 (292 – 400)	315±23 (289 – 353)
a	8.2	8.0±0.7 (6.5 – 9.4)	11.7±1.1 (9.3 – 13.4)	10.7±1.4 (7.4 – 13.2)
b’	2.1	1.7±0.1 (1.5 – 2.1)	2.6±0.5 (1.9 – 3.7)	2.6±0.6 (1.8 – 3.6)
c	23.3	15.0±2.6 (12.4 – 23.3)	12.2±1.4 (10.5 – 16.3)	17.0±3.0 (13.9 – 26.0)
c’	0.8	1.2±0.2 (0.8 – 1.6)	1.6±0.2 (1.3 – 2.0)	0.9±0.1 (0.5 – 1.1)
V or T %	85.7	83.9±1.3 (81.8 – 87.2)	54.1±12.9 (34 – 78)	82.6±1.6 (80.2 – 87.8)
Body diameter	30	33±2.9 (30 – 38)	29±2.6 (26 – 37)	30±3.4 (26 – 41)
Stylet length	13	13±0.8 (12 – 14)	9±0.6 (9 – 10)	9±0.8 (7 – 10)
Ant. end to SE pore		73±11.2 (57 – 93)	84±7.5 (72 – 104)	80±9.9 (65 – 94)
Spicule length			19±1.2 (17 – 21)
Tail length	11	18±3.1 (11 – 22)	28±3.7 (19 – 35)	19±3.7 (11 – 24)