Fergusobia minimus, Davies, Kerrie A., Giblin-Davis, Robin M., Ye, Weimin, Taylor, Gary S. & Thomas, W. Kelley, 2013

Davies, Kerrie A., Giblin-Davis, Robin M., Ye, Weimin, Taylor, Gary S. & Thomas, W. Kelley, 2013, Nematodes from galls on Myrtaceae. V. Fergusobia from large multilocular shoot bud galls from Angophora and Eucalyptus in Australia, with descriptions of six new species, Zootaxa 3741 (1), pp. 101-140 : 122-126

Fergusobia minimus n. sp. Lisnawita

( Figs 7 , 9 M, 10L)

Measurements. Table 6.

Holotype Parthenogenetic females Males Infective females

Parthenogenetic

female

n 20 20 2 Length 382 368 ±38.2 (304–421) 427 ±34.4 (368–502) 439 (419–458) a 10.0 10.0 ±1.0 (7.5–11.1) 13.2±1.3 (11.2–15.7) 11.2 (10.4–11.9) b’ 2.6 2.8±0.6 (2.0–4.3) 3.5±0.6 (2.9–5.5) 2.7 (1.9–3.5) c 20.8 14.8±4.0 (9.7–26.1) 13.5±2.4 (10.7–20.2) 17.9 (9.3–26.6) c’ 1.9 2.1±0.6 (0.6–3.3) 1.8±0.3 (1.1–2.4) 1.0 (0.9–1.2) V% 79.2 84.1±4.7 (65.0–87.1) 80.8 (79.9–81.6) T% 68.5±6.6 (51.5–83.0)

Material examined. 24 parthenogenetic ♀, 2 pre-parasitic infective ♀, and 20 ♂; from parkland near Mrs. Macquarie’s Chair, Sydney, NSW, Australia (33°51.91´S 151°1.91´E), roadside at Taringa, Brisbane, Queensland, Australia, growing in Hyde Park, Townsville, Queensland, Australia (19º16.34’S, 146º47.81’ E), and from roadside vegetation at Sarina, Queensland, Australia (21º25.76’S, 149º13.16’E). From multilocular shoot bud galls on Eucalyptus tereticornis . Coll. K.A. Davies, 3.vii.2004; K.A. Davies, 17.vii.1999; K.A. Davies 14.vii.2004, and K.A. Davies & R.M. Giblin-Davis, 20.vii.2008, respectively.

Holotype: A parthenogenetic female, on a slide together with an infective female and a male paratype, deposited in the ANIC, Canberra, ACT, Australia, collected at Sydney, NSW, data as above.

Paratypes: (collection data as above) deposited at the WINC, The University of Adelaide, SA, Australia, 6 parthenogenetic ♀ and 6 ♂; The Australian National Museum, Sydney, NSW, Australia, 15 parthenogenetic ♀, 1 pre-parasitic infective ♀ and 10 ♂; the Queensland Museum, South Brisbane, QLD, Australia, 30 parthenogenetic ♀ and 5 ♂; and at the USDA Nematode Collection, Beltsville, MD, USA 10 parthenogenetic ♀ and 2 ♂.

Description. Parthenogenetic female. From multilocular shoot bud galls on E. tereticornis . Body dorsally curved when relaxed by heat, with ventral side convex to form C-shape, occasionally more tightly curved ( Fig. 7 ). Smaller in size than pre-parasitic females and males; body tapering gradually posterior to vulva to form conoid tail, dorsal side concave. Cuticle with obscure annules, unmeasured; longitudinal striae not visible with light microscope. Lateral fields not seen.

Cephalic region diameter ~70% of body diameter immediately posterior, offset, unstriated; rounded outline and circum-oral area flat in lateral view. Small stylet with cone ~40% of total length, basal knobs well defined, ~2µm across at base, round.

Orifice of dorsal pharyngeal gland ~1 µm posterior to stylet knobs. Anterior fusiform part of digestive tract diameter 50–75% of body diameter, length ~2 times diameter. Lumen of tract broadening at ~50% length of dorsal pharyngeal gland. Pharyngeal glands large, occupying ~50% of body diameter, extending 23–50 (mean 36) % of total body length. Gland nucleus not prominent.

Secretory/excretory pore opening at 25–30 % body length; large cell/s surrounding duct; secretory/excretory cell not seen. Hemizonid shallow, ~15 µm anterior to pore.

Reproductive tract variable in length, extending part-way along dorsal pharyngeal gland or to nerve ring; outstretched or reflexed (5 of 20 specimens); oviduct with oocytes in two rows; uterus mostly containing no eggs or sometimes one egg (3 of 20 specimens), not extensile; vulva usually flat but occasionally lips protruding (1 of 20 specimens). Anus a tiny pore, rectum not obviously sclerotised, difficult to see. Tail variable in length, half to 3 times anal body diameter, tapering, tip bluntly rounded.

Infective pre-parasitic female. From multilocular shoot bud galls on E. tereticornis . Infecting mature larval stage of Fergusonina sp. or pupa. Body open C-shape when relaxed by heat, greatest curvature in tail region with ventral side convex; maximum body diameter at mid-body length or at vulva; body narrowing gradually posterior to vulva. Cuticle with obscure annules, not measured; longitudinal striations apparent when viewed with light microscope; lateral fields not seen.

Cephalic region diameter 62 % of body diameter immediately posterior, offset, ~3 µm long; circum-oral area flat or depressed; stylet slender, weakly sclerotised with small round basal knobs ~1.5 µm across; cone 40–50 % of total length.

Orifice of dorsal pharyngeal gland not seen; pharyngeal glands occupying ~33% body diameter, extending over intestine to average 37 (28–53) % of body length. Anterior fusiform part of digestive tract diameter 59–67 % of body diameter, length about double diameter.

Secretory/excretory pore with obscure duct; secretory/excretory cell not seen. Hemizonid ~5 µm anterior to secretory/excretory pore.

Uterus packed with sperm in inseminated females; vagina angled towards anterior end; reproductive tract extending to nerve ring; hypertrophied in length. Vulval lips broad and flat. Tail broad, arcuate; length ~1–1.3 times diameter at anus, tip hemispherical.

Male. From multilocular shoot bud galls on E. tereticornis . Body arcuate to occasionally C-shaped when relaxed by heat, tail region more or less curved ventrally. Cuticle with obscure annules, width not measured; longitudinal striations not clearly seen when viewed with light microscope; lateral fields not seen.

Cephalic region diameter ~65 % of body diameter immediately posterior, offset; circum-oral area flat; stylet with cone 40 % of total length, stylet knobs round, ~2 µm across. Anterior fusiform part of digestive tract occupying 47–81 % of body diameter, length ~2–3 times diameter. Orifice of dorsal pharyngeal gland ~2 µm posterior to stylet knobs. Pharyngeal glands occupying ~30–50 % of body diameter, extending over intestine to 18– 34 (mean 28) % of total body length. Gland cell large, but not obvious. Lumen of intestinal tract broadening halfway along gland.

Secretory/excretory pore opening at ~50–100 % of length of pharyngeal gland; duct obscure, secretory/ excretory cell not seen. Hemizonid ~15 µm anterior to secretory/excretory pore.

Reproductive tract with single testis, variable in length, extending to nerve ring or more usually overlapping dorsal pharyngeal gland; outstretched; testis, seminal vesicle and vas deferens not clearly differentiated. Bursa peloderan; smooth; usually prominent; arising 12–28 (mean 21) % along length of body from tail tip. Spicules paired, angular (90°) at mid-length, moderately sclerotised; manubrium similar width to shaft, occasionally wider, offset; blade broad, opening unclear. Inconspicuous muscles associated with cloaca. Tail more or less ventrally curved; length ~1–2.5 times diameter at cloaca; tip bluntly rounded.

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

Morphologically, parthenogenetic females are most similar to those of F. brittenae , F. cosmophyllae , F. diversifoliae , F. floribundae n. sp., F. morrisae , and F. ptychocarpae .

From phylogenetic analyses based on sequences of D2/D3 and COI, F. minimus n. sp. is genetically similar to F. brittenae .

In having a C-shape, the parthenogenetic female of F. minimus n. sp. differs from F. rileyi (almost straight to arcuate); and from F. brevicauda , F. curriei , F. delegatensae , F. fasciculosae , F. fisheri , F. nervosae , and F. viridiflorae (open C-shape). In length (303–421 µm), it is shorter than the parthenogenetic female of F. i n d i c a (525–626 µm) and F. magna (418–780 µm); and longer than F. cajuputiae (221–273 µm), F. jambophila (195–300 µm), F. leucadendrae (205–303 µm), and F. philippinensis (229–310 µm). The cephalic region of F. minimus n. sp. is not retracted when heat killed, as occurs commonly in F. floribundae n. sp. and F. pimpamensis n. sp. The circum-oral area in the parthenogenetic female of F. minimus n. sp. is flat, differing from F. camaldulensae , F. eugenioidae , F. morrisae , and F. pohutukawa , in which it is raised. The stylet (4–8 µm) is shorter than in F. camaldulensae (11–13 µm) and F. dealbatae (9–10 µm). The shape of the body posterior to the vulva (slender, arcuate, with bluntly rounded tip) differs from that of F. p o ro s a e (shorter); and from F. juliae , F. microcarpae , F. quinquenerviae , and F. tumifaciens (with more broadly rounded tips). The stylet length is mostly shorter (4–8 µm, mean 6 µm) than in F. brittenae (8–11 µm, mean 9 µm) and F. ptychocarpae (8–13 µm, mean 10 µm). The stylet length (4–8 µm) is also mostly shorter than in F. cosmophyllae n. sp. (8–9 µm) and the secretory/excretory pore is more anterior (55–116 µm vs 158–221 µm from the anterior end). It is also mostly shorter than in F. diversifoliae n. sp. (stylet 8–11 µm, mean 9 µm), and the latter does not have the large cells surrounding the duct to the excretory pore that occur in F. minimus n. sp.

The infective female of F. minimus n. sp. differs in shape (open C) from that of F. eugenioidae , F. juliae , F. morrisae , and F ptychocarpae (strongly curved in posterior region); from F. camaldulensae (arcuate); and from F. rileyi (almost straight). In length (419–458 µm), the infective female is smaller than in F. magna (537–633 µm) and larger than in F. brevicauda (350–410 µm), F. cajuputiae (239–309 µm), F. dealbatae (307–347 µm), F.

fasciculosae (268–332 µm), F. leucadendrae (227–291 µm), F. microcarpae (302–341 µm), F. p oro s a e (277–300 µm), F. quinquenerviae (259–325 µm), and F. viridiflorae (321 µm). The ratio a (10–12) n. sp. is larger than in F. cosmophyllae n. sp. (4–7). The stylet length (4–5 µm) is shorter than F. curriei (7–9 µm), F. delegatensae (8–11 µm), F. diversifoliae (9–11 µm) and F. pimpamensis n. sp. (6–10 µm). Shape of the body posterior to the vulva (straight, with hemispherical tip) differs from that of F. fisheri and F. nervosae (conoid, with broadly rounded tips), and from F. philippinensis (truncate tip). The anterior fusiform part of the digestive tract is broader (length ~ 2 times diameter) than F. floribundae (length 3–4 times diameter). Fergusobia brittenae has a more posterior vulva (80–82%) than F. minimus n. sp. (72–77%).

The male shape of F. minimus n. sp. (arcuate to C-shaped) differs from F. brittenae , F. curriei , F. juliae , and F. ptychocarpae (J-shaped); from F. tumifaciens (barely J-shaped); and from F. rileyi (straighter shape). The male body is longer (368–502 µm), than F. cajuputiae (286–364 µm), F. fasciculosae (274–336 µm), F. jambophila (200–390 µm), F. nervosae (277–312 µm), F. p o ro s a e (270–326 µm), and F. quinquenerviae (256–329 µm). The stylet (4–7 µm) is shorter than that of F. dealbatae (9 µm), F. diversifoliae (9–11 µm), F. eugenioidae (9–11 µm) and F. f i s h e r i (8–11 µm). The tail shape (arcuate, with a bluntly rounded tip) differs from that of the male of F. magna (more slender); and F. philippinensis (truncate tip). The spicule is longer (16–25 µm) than in F. cosmophyllae n. sp. (12–15 µm) and F. leucadendrae (14–17 µm). The bursa is short (arising at 12–28% of body length), differing from that of F. camaldulensae (50–70%), F. delegatensae n. sp. (~90%), F. floribundae n. sp. (23–55%), F. morrisae (75–83%), F. pimpamensis n. sp. (61–80%), F. pohutukawa (~95%), and F. viridiflorae (~80%). The male of F. minimus n. sp. has a sturdy spicule compared to the slender spicule of F. brevicauda . Males of F. minimus n. sp. have a relatively shorter pharyngeal gland (b’ 2.9–5.5) and bursa (12–28% of total body length) than F. microcarpae (b’ 2.0–3.1, bursa 24–47% of total body length).

Etymology. Named for its small (mini -) stylet (- mus meaning mouth).

Figures

FIGURE 7. Fergusobia minimus n. sp. ex E. tereticornis (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 9. Habitus drawings of Fergusobia spp. collected from large multilocular leaf bud galls: A— F. floribundae n. sp. from Angophora floribunda; B— F. pimpamensis n. sp. from Angophora sp; C—undescribed species from E. nr. acmenioides; D—undescribed species from E. amygdalina; E— F. delegatensisae n. sp. from E. delegatensis; F—undescribed species from E. pauciflora; G—undescribed species from E. racemosa; H—undescribed species from E. obliqua; I— F. diversifoliae n. sp. from E. diversifolia; J—undescribed species from E. blakelyi; K— F. brittenae from E. camaldulensis; L—undescribed species from E. dealbata; M— F. minimus n. sp. from E. tereticornis; N— F. cosmophyllae n. sp. from E. cosmophylla; O—undescribed species from E. robusta; P—undescribed species from Eucalyptus sp. at Woodburn, NSW. Scale bars = 50 µm.