Morphological and molecular characterisation of Californian species ...

Studies on Metaporcelaimus
MEASUREMENTS
See Table 1.
DESCRIPTION
Adult
Slender to very slender nematodes of medium size,
1.99-2.48 mm long. Body cylindrical, tapering towards
both extremities, but more so towards posterior end as
tail is conical. Habitus curved ventrad after fixation,
especially in posterior body region, G-shaped. Cuticle
1.5-2 μm at anterior region, 2.5-3 μm in mid-body and
3-4 μm on tail, typical of genus with outer layer thin and
bearing fine but distinct transverse striation throughout
body, and inner layer thicker than inner. Cervical lacunae
absent. Lateral chord 9-15 μm wide, occupying 17-24%
of mid-body diam., gland bodies perceptible in some
specimens. Lip region offset by deep constriction, 2.6-2.9
times as broad as high and one-fourth to one-third (25-
32%) of body diam. at neck base, lips separated, angular,
labial and cephalic papillae low. Amphid fovea funnelshaped,
its aperture 8-9.5 μm orca three-fifths (57-68%)
of lip region diam. Cheilostom nearly cylindrical, lacking
any differentiation. Odontostyle typical of genus, 5.2-5.8
times as long as wide, 0.9-1.0 times as long as lip region
diam., and 0.57-0.69% of body length, aperture 9-11 μm
long or occupying two-thirds to three-fourths (67-75%)
its length. Guiding ring plicate. Odontophore linear, rodlike,
1.8-2.0 odontostyle lengths long. Anterior region of
pharynx enlarging very gradually, basal expansion 6.9-
10.3 times as long as broad, 4.5-5.6 times as long as body
diam., occupying 47-52% of total neck length, pharyngeal
gland nuclei located as follows: DN = 59-63, DO-DN =
21, 24 μm (n= 2), S 1 N 1 = 67-71, S 1 N 2 = 76-77, S 2 N =
88-90. Nerve ring at 142-172 μm or 30-36% of total neck
length from anterior end. Cardia conical, (13-18) × (10-
14) μm, its junction with pharyngeal base surrounded by
weak ring-like structure which is distinctly asymmetrical
as it appears more developed on dorsal surface, forming a
small lobe. Tail conical with rounded tip, ventrally nearly
straight and dorsally more convex, and barely bent dorsad
at its terminus, inner core slightly notched on its dorsal
surface, nearly reaching tail tip, hence no hyaline portion.
Two pairs of caudal pores, subdorsal, both in posterior
halfoftail.
Female
Genital system didelphic-amphidelphic, with both
branches equally and well developed, anterior 411-
453 μm or 17-19% of body length, and posterior 374-
465 μm or 16-19% of body length. Ovaries large, anterior
161-175 μm, posterior 168-209 μm long; oocytes arranged
first in two or more rows, then in a single row.
Oviduct 126-155 μm long or 2.3-2.8 times corresponding
body diam., consisting of slender part with prismatic
cells and well developed pars dilatata with distinct lumen.
Oviduct and uterus separated by a sphincter. Uterus 201-
262 μm long or 3.7-4.7 times corresponding body diam.
and tripartite, that is consisting of a spheroid distal portion
close to sphincter, an intermediate muscular section
with narrow lumen, and a proximal portion with wider
lumen. Abundant sperm cells present in both distal and
proximal uterine regions. Vagina extending inwards for
25-32 μm, occupying up to one-half (46-50%) of body
diam., pars proximalis (17-24) × (15-18) μm, with somewhat
sigmoid walls and surrounded by weak musculature,
pars refringens with two adjacent trapezoidal to dropshaped
pieces measuring 7 × (4-5) μm, combined width
10-12 μm, pars distalis 2 μm long. Two cells, one anterior
and another posterior, present on both sides of vagina.
Vulva a post-equatorial, transverse slit. Prerectum 2.9-3.7,
rectum 1.1-1.3 anal body diam. long.
Male
Genital system diorchic, testes opposed. In addition
to adcloacal pair, situated at 11-14 μm from cloacal
aperture, a series of 6-7 irregularly spaced, 14-31 μm
apart, ventromedian supplements located outside range of
spicules and at 61-82 μm from adcloacal pair. Spicules
well curved ventrad, robust, 4.3-5.4 times as long as wide
and 1.5-2.0 times as long as cloacal body diam. Lateral
guiding pieces 15-20 μm long, 5.4-6.8 times as long as
wide, with ventral arm distinctly longer than dorsal.
TYPE LOCALITY AND HABITAT
Sir Francis Drake Boulevard, Platform Bridge Road,
Marin County, California, USA, where the new species
was collected in association with California bay laurel
(Umbellularia californica).
TYPE MATERIAL
Female holotype and two female and three male paratypes,
deposited in the nematode collection of the University
of Jaén, Spain. One male paratype deposited with
USDA Nematode Collection, Beltsville, MA, USA.
Vol. 00(0), 2012 7